WO2022179544A1

WO2022179544A1 - Handwriting drawing method, apparatus, medium, and interactive tablet

Info

Publication number: WO2022179544A1
Application number: PCT/CN2022/077604
Authority: WO
Inventors: 林峻弘
Original assignee: 广州视源电子科技股份有限公司; 广州视睿电子科技有限公司
Priority date: 2021-02-25
Filing date: 2022-02-24
Publication date: 2022-09-01
Also published as: CN114972558A

Abstract

The embodiments of the present application provide a handwriting drawing method, an apparatus, a medium, and an interactive tablet. Said method comprises: acquiring touch point information corresponding to a handwriting operation, and acquiring, according to the touch point information, a handwriting axis corresponding to the handwriting operation; according to the size of the handwriting axis and a preset rendering line width, determining a target buffer region; performing compression processing on the target buffer region according to a preset texture resolution to obtain an SDF texture buffer region; calculating a shortest distance from a position corresponding to each texture pixel point of the SDF texture buffer region in the target buffer region to the handwriting axis, and determining the shortest distance as the value of the texture pixel point of the corresponding SDF texture buffer region to obtain an SDF texture image; allocating a rendering buffer region according to the target buffer region, and establishing a mapping relationship between the rendering buffer region and the SDF texture image; and rendering the rendering buffer region on the basis of bilinear interpolation sampling, and then obtaining a handwriting. The present application has small rendering overhead, can improve rendering efficiency, and can timely and effectively display handwriting.

Description

Writing and handwriting drawing method, device, medium and interactive tablet

This application claims the priority of the Chinese patent application filed on February 25, 2021, with the application number 202110209969.X and the invention titled "writing and handwriting drawing method, device, medium and interactive tablet", the entire content of which is Incorporated herein by reference.

technical field

The embodiments of the present application relate to the field of interactive tablet counting, for example, to a method, device, medium, and interactive tablet for drawing handwriting.

Background technique

In the field of interactive tablet, handwriting function, as one of the increasingly important functions of interactive smart tablet, has been widely used in people's work and study, which greatly improves people's work and study effect. For example, in a teaching scenario, the teacher can write handwriting on the current interactive tablet, and students can view the handwriting written by the teacher through the interactive tablet. In the process of implementing the present application, it is found that there are at least the following problems in the related art: after a large amount of handwriting is written on the interactive tablet, the rendering efficiency is low, and the handwriting cannot be drawn in time and effectively.

SUMMARY OF THE INVENTION

In order to overcome the problems existing in the related art, the present application provides a method, device, medium and interactive tablet for drawing handwriting, which have the advantages of improving rendering efficiency and displaying handwriting in a timely and effective manner.

According to a first aspect of the embodiments of the present application, there is provided a method for drawing handwriting, comprising the following steps:

Receive the writing operation on the touch screen;

acquiring touch point information corresponding to the writing operation, and acquiring the handwriting axis corresponding to the writing operation according to the touch point information;

Determine the target buffer according to the size of the handwriting axis and the preset rendering line width;

Compress the target buffer according to the preset texture resolution to obtain an SDF texture buffer;

Calculate the shortest distance from the position corresponding to each texel point of the SDF texture buffer in the target buffer to the handwriting axis, and determine the shortest distance as the texture of the corresponding SDF texture buffer The value of the pixel point to obtain the SDF texture image;

Allocate a rendering buffer according to the target buffer, and establish a mapping relationship between the rendering buffer and the SDF texture image;

The handwriting is obtained after rendering the rendering buffer based on bilinear interpolation sampling;

The handwriting is displayed on the touch screen.

According to a second aspect of the embodiments of the present application, there is provided a writing handwriting drawing device, comprising:

The writing operation receiving module is used for receiving the writing operation on the touch screen;

a handwriting axis acquisition module, configured to acquire touch point information corresponding to the writing operation, and acquire the handwriting axis corresponding to the writing operation according to the touch point information;

a target buffer determining module, configured to determine a target buffer according to the size of the handwriting axis and a preset rendering line width;

a texture buffer acquisition module, configured to compress the target buffer according to a preset texture resolution to obtain an SDF texture buffer;

The texture image acquisition module is used to calculate the shortest distance from the position corresponding to each texel point of the SDF texture buffer in the target buffer to the handwriting axis, and determine the shortest distance as the corresponding The value of the texture pixel point of the SDF texture buffer is described to obtain the SDF texture image;

a mapping relationship acquisition module, configured to allocate a rendering buffer according to the target buffer, and establish a mapping relationship between the rendering buffer and the SDF texture image;

a writing handwriting acquisition module, used for obtaining writing handwriting after rendering the rendering buffer based on bilinear interpolation sampling;

The handwriting display module is used for displaying the writing handwriting on the touch screen.

According to a third aspect of the embodiments of the present application, an interactive tablet is provided, including a touch screen, a processor, and a memory; the memory stores a computer program, and the computer program is adapted to be loaded and executed by the processor as described above method of writing handwriting.

According to a fourth aspect of the embodiments of the present application, there is provided a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, implements the above-described method for drawing handwriting.

The embodiment of the present application performs compression processing on the target buffer according to the preset texture resolution to obtain an SDF texture buffer; calculates the position corresponding to each texture pixel of the SDF texture buffer in the target buffer to the The shortest distance of the handwriting axis, and the shortest distance is determined as the value of the texture pixel point of the corresponding SDF texture buffer to obtain an SDF texture image; the SDF texture image is subjected to bilinear interpolation sampling to obtain interpolation sampling The distance value between each texture pixel point and the handwriting axis, and according to the mapping relationship between the rendering buffer and the SDF texture image, and then rendering the rendering buffer based on bilinear interpolation sampling to obtain writing handwriting, Therefore, the handwriting is displayed on the touch screen, and only two triangles need to be rendered through the SDF texture image, the rendering overhead is small, the rendering efficiency is improved, and the handwriting can be displayed in a timely and effective manner. When the writing handwriting does not change, and writing handwriting of different widths needs to be rendered, only one preprocessing is required to generate an SDF texture image, and then the same SDF texture image is directly used to render and display the writing handwriting of different widths. In the present application, because the SDF texture is to describe the distance information rather than the color information, and then combined with the bilinear interpolation sampling method, the problem of edge distortion is not easy to occur when the SDF texture image of small resolution can be used to draw large-resolution handwriting.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not limiting of the present application.

For better understanding and implementation, the present application is described in detail below with reference to the accompanying drawings.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present application or related technologies more clearly, the following briefly introduces the accompanying drawings that are used in the description of the embodiments or related technologies. Obviously, the drawings in the following description are the drawings of the present application For some embodiments of the present invention, for those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

Fig. 1 is the schematic diagram of the handwriting that needs to be drawn in one embodiment of the application;

2 is a schematic diagram of triangulating handwriting in the related art of the application;

3 is an effect diagram of rendering handwriting in the related art of the application;

4 is a flowchart of a method for drawing handwriting according to an embodiment of the application;

5 is a schematic diagram of a handwriting axis shown in an embodiment of the application;

6 is a schematic diagram of the shortest distance shown in an embodiment of the application;

7 is a flowchart of a method for obtaining a handwriting axis according to an embodiment of the application;

8 is a flowchart of a method for determining an SDF texture image according to an embodiment of the present application;

FIG. 9 is a flowchart of a method for obtaining writing handwriting according to an embodiment of the application;

10 is an effect diagram of the drawn handwriting shown in an embodiment of the application;

Fig. 11 is another embodiment of the present application showing the effect diagram of drawn handwriting;

12 is a schematic block diagram of a writing handwriting drawing device according to an embodiment of the application;

13 is a schematic block diagram of a handwriting axis acquisition module according to an embodiment of the application;

14 is a schematic block diagram of a texture image acquisition module according to an embodiment of the application;

15 is a schematic block diagram of a writing handwriting acquisition module according to an embodiment of the application;

FIG. 16 is a schematic structural diagram of an interactive tablet according to an embodiment of the present application.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present application clearer, the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

It should be clear that the described embodiments are some, but not all, embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

Where the following description refers to the drawings, the same numerals in different drawings refer to the same or similar elements unless otherwise indicated. The implementations described in the illustrative examples below are not intended to represent all implementations consistent with this application. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present application, as recited in the appended claims.

In the description of this application, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects, and are not necessarily used to describe a specific sequence or sequence, nor can understood as indicating or implying relative importance. For those of ordinary skill in the art, the meanings of the above terms in the present application can be understood according to the situation. As used in this application and the appended claims, the singular forms "a," "the," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The words "if"/"if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining". Also, in the description of the present application, unless otherwise specified, "a plurality" means two or more. "And/or", which describes the association relationship of the associated objects, means that there can be three kinds of relationships, for example, A and/or B, which can mean that A exists alone, A and B exist at the same time, and B exists alone. The character "/" generally indicates that the associated objects are an "or" relationship.

In order to better understand the technical solutions of the present application, the method for drawing handwriting in the related art will be described below. It should be noted that the writing handwriting mentioned in the embodiments of the present application is a special writing handwriting, please refer to FIG. 1 , for example, the starting endpoint, the ending endpoint and the corner of the writing handwriting are all arc shapes. Please refer to FIG. 2 and FIG. 3 , the method for drawing the writing handwriting in the related art is to obtain the handwriting axis of the writing operation according to the touch information of the writing operation; The polygon mesh outline of the writing handwriting; then triangulation is performed in the polygon mesh outline, and finally all triangles in the polygon mesh outline are rendered to obtain the writing handwriting. In the process of realizing this application, it is found that there are at least the following problems in the related art: since there are already many triangles corresponding to a writing handwriting, once the writing handwriting increases, the data of the triangles will become very huge, thereby reducing the rendering time. Shows the efficiency of handwriting. Moreover, even if there is a slight change in writing, the polygon mesh outline needs to be regenerated, and then the regenerated triangles in the polygon outline are rendered, which increases the complexity and reduces the rendering efficiency. To this end, the present application proposes a method for drawing handwriting.

The writing handwriting drawing method shown in the embodiments of the present application may be executed by a writing handwriting drawing device, the writing handwriting drawing device may be implemented by means of software and/or hardware, and the writing handwriting drawing device may be two or more physical entities Composition can also be a physical entity composition. For example, the writing and handwriting drawing device may be a smart device such as a computer, a mobile phone, a tablet or a smart interactive tablet.

For ease of understanding, in the embodiments, an interactive tablet is used as a writing handwriting drawing device for exemplary description. Among them, the interactive tablet can be an integrated device that controls the content displayed on the display tablet and realizes human-computer interaction through touch technology. one or more functions.

Generally speaking, an interactive tablet includes at least one display screen. For example, the interactive tablet is equipped with a display screen with a touch function, and the display screen can be a capacitive screen, a resistive screen or an electromagnetic screen. In one embodiment, the user can realize the touch operation by touching the display screen with a finger or a stylus. Correspondingly, the interactive tablet detects the touch position, and determines a response scheme according to the touch operation corresponding to the touch position, and then performs the touch operation. response to implement the touch function. For example, it is determined according to the touch position that the corresponding touch operation is writing handwriting, and at this time, the response scheme is displaying handwriting. In one embodiment, at least one type of operating system is installed on the interactive tablet, wherein the operating system includes but is not limited to an Android system, a Linux system, and a Windows system. In one embodiment, the interactive tablet can install at least one application program based on the operating system, and in the embodiment, an application program with a writing function is used as an example for description. For example, an electronic whiteboard application with a writing function is installed in the interactive tablet. The application program may be an application program that comes with the operating system, or an application program downloaded from a third-party device or server, and the interactive tablet may also be an application program itself. Optionally, in addition to the writing function, the application program also has other editing functions, such as functions of writing, inserting tables, inserting pictures, inserting multimedia, inserting graphics, and drawing tables.

Example 1

The writing and handwriting drawing method disclosed in the embodiments of the present application is applied to an electronic device, and the following description takes the electronic device as an interactive tablet.

The method for drawing handwriting provided by the embodiments of the present application will be described in detail below with reference to FIGS. 4 to 11 .

Please refer to FIG. 4 , which is a flowchart of a method for drawing handwriting according to an embodiment of the present application.

The method for drawing handwriting provided by the embodiment of the present application includes the following steps:

Step S110: Receive a writing operation on the touch screen.

In some examples, a writing interface is displayed by turning on the electronic whiteboard on the touch screen, and the interactive tablet will receive the writing operation on the touch screen when touching and writing on the writing interface by hand or a stylus or other writing tool.

Step S120: Acquire touch point information corresponding to the writing operation, and acquire the handwriting axis corresponding to the writing operation according to the touch point information.

Referring to FIG. 5 , touch point information can be obtained by detecting the writing operation, and a handwriting axis corresponding to the writing operation can be obtained according to the touch point information.

Step S130: Determine the target buffer area according to the size of the handwriting axis and the preset rendering line width.

In some examples, the size of the handwriting axis includes the length of the handwriting axis and the width of the handwriting axis; wherein the length of the handwriting axis is the distance between the start point of the handwriting axis and the end point of the handwriting axis , the width of the handwriting axis is the maximum distance between the two ends of the handwriting axis in the length direction perpendicular to the handwriting axis.

In some examples, the rendering line width is the width of the handwriting displayed by drawing, which can be set as required.

The buffer is a part of the memory space, that is to say, a storage space of a specified size is reserved in the memory space for temporary storage of input or output data. This part of the reserved space is called a buffer, and the purpose is to reduce The number of times of data reading improves data processing efficiency. In this embodiment of the present application, the target buffer is the data temporarily stored for determining the rendering buffer and the SDF texture buffer.

In some examples, the determining the target buffer according to the size of the handwriting axis and the preset rendering line width includes: adding the horizontal length of the handwriting axis to the preset rendering line width, and adding the handwriting axis to the preset rendering line width. The vertical length of the axis is added to the preset rendering line width to obtain the target buffer. In this embodiment of the present application, the target buffer is obtained by adding the horizontal length of the handwriting axis to the preset rendering line width, and adding the vertical length of the handwriting axis to the preset rendering line width, so that the handwriting can be written. The display can be rendered completely unobstructed at render time.

Step S140: Compress the target buffer according to the preset texture resolution to obtain an SDF texture buffer.

Among them, SDF (signed distance filed, directional distance field) stores the distance for each pixel value. In some examples, the preset texture resolution may be a texture resolution determined by a preset compression factor. For example, for the target buffer with a resolution of 1600×512, if the preset compression factor is 32, Then, the target buffer can be compressed according to the scaling factor of 32 to obtain an SDF texture buffer, and the texture resolution of the SDF texture buffer is 50×16 at this time. The preset texture resolution can also be a texture resolution that is not directly preset. For example, for the target buffer with a resolution of 1600×512, if the preset texture resolution is 50×16, the compression coefficient can be calculated as 32, and then compress the target buffer to obtain an SDF texture buffer with a texture resolution of 50×16.

Step S150: Calculate the shortest distance from the position corresponding to each texel point of the SDF texture buffer in the target buffer to the handwriting axis, and determine the shortest distance as the corresponding SDF texture buffer The value of the texture pixel point of the area, obtain the SDF texture image.

Referring to FIG. 6 , calculating the shortest distance from the position corresponding to each texel point of the SDF texture buffer in the target buffer to the handwriting axis includes: traversing each point of the handwriting axis and the target For the distance in the buffer area corresponding to each texture pixel point of the SDF texture buffer area, the value with the smallest distance is selected as the shortest distance.

Step S160: Allocate a rendering buffer according to the target buffer, and establish a mapping relationship between the rendering buffer and the SDF texture image.

In some examples, the target buffer has the same resolution as the render buffer, that is, according to the resolution of the target buffer, a render buffer with the same resolution as the target buffer is allocated.

Step S170 : obtaining writing handwriting after rendering the rendering buffer based on bilinear interpolation sampling.

Bilinear interpolation, also known as bilinear interpolation. Mathematically, bilinear interpolation is a linear interpolation extension of an interpolation function with two variables, and its core idea is to perform a linear interpolation in two directions respectively.

In the embodiment of the present application, according to the mapping relationship between the rendering buffer and the SDF texture image, bilinear interpolation is used to interpolate and sample the rendering buffer to obtain writing handwriting, which can make the edge of the writing handwriting smoother.

Step S180: Display the handwriting on the touch screen.

The embodiment of the present application performs compression processing on the target buffer according to the preset texture resolution to obtain an SDF texture buffer; calculates the position corresponding to each texture pixel of the SDF texture buffer in the target buffer to the The shortest distance of the handwriting axis, and the shortest distance is determined as the value of the texture pixel point of the corresponding SDF texture buffer to obtain an SDF texture image; the SDF texture image is subjected to bilinear interpolation sampling to obtain interpolation sampling The distance value between each texture pixel point and the handwriting axis, and according to the mapping relationship between the rendering buffer and the SDF texture image, and then rendering the rendering buffer based on bilinear interpolation sampling to obtain writing handwriting, Therefore, the handwriting is displayed on the touch screen, and only two triangles need to be rendered through the SDF texture image, the rendering overhead is small, the rendering efficiency is improved, and the handwriting can be displayed in a timely and effective manner. When the writing handwriting does not change, and writing handwriting of different widths needs to be rendered, only one preprocessing is required to generate an SDF texture image, and then the same SDF texture image is directly used to render and display the writing handwriting of different widths. In the present application, since the SDF texture describes distance information rather than color information, and combined with the bilinear interpolation sampling method, the problem of edge distortion is not easy to occur when large-resolution handwriting drawing can be performed by using a small-resolution SDF texture image.

Please refer to FIG. 7 , which is a flowchart of a method for obtaining a handwriting axis according to an embodiment of the present application.

In some examples, in step S120, the touch point information is a plurality of consecutive sampling points collected by the touch screen according to the writing operation; the touch point information obtained in response to the writing operation on the touch screen, according to the touch The point information obtains the handwriting axis corresponding to the writing operation, including:

Step S121: obtaining a touch point connection line according to the two adjacent sampling points;

Step S122: Obtain the handwriting axis corresponding to the writing operation according to the touch point connection.

The touch point connection line is obtained by connecting two adjacent sampling points, thereby realizing the quick and accurate acquisition of the handwriting axis.

Please refer to FIG. 8 , which is a flowchart of a method for determining an SDF texture image according to an embodiment of the present application.

In some examples, the SDF texture buffer includes a horizontal texel count and a vertical texel count. In step S150, the shortest distance from the position corresponding to each pixel of the SDF texture buffer in the target buffer to the handwriting axis is calculated, and the shortest distance is determined as the corresponding SDF The value of the texture pixel point of the texture buffer to obtain the SDF texture image, including:

Step S151: Acquire the number of horizontal texels and the number of vertical texels of the SDF texture buffer.

Step S152: Divide the target buffer into a corresponding number of texture grids according to the number of horizontal texels and the number of vertical texels.

For example, if the number of horizontal texture pixels and the number of vertical texture pixels are 50 and 16 respectively, the number of horizontal texture grids divided by the target buffer is 50 and the number of vertical texture grids is 16; The number of texture pixels and the number of vertical texture pixels are 50 and 16 respectively, then the number of horizontal texture grids divided by the target buffer is 25 and the number of vertical texture grids is 8, then the horizontal texture divided by the target buffer The number of meshes is 25 and the number of longitudinal texture meshes is 8.

Step S153: Calculate the shortest distance from the center point of each texture grid in the target buffer to the handwriting axis.

Step S154: Determine the shortest distance as the value of the corresponding texture pixel of the SDF texture buffer to obtain an SDF texture image.

By dividing the target buffer into texture grids corresponding to the SDF texture buffer, and then calculating the shortest distance from the center point of each texture grid to the handwriting axis, the shortest distance is determined as The corresponding value of the texture pixel point of the SDF texture image, so that the distance information of the target buffer under high resolution can be fully preserved. The texel in the SDF texture image records the distance value instead of the color value, so that the image compression and stretching will not greatly affect the display effect.

Please refer to FIG. 9 , which is a flowchart of a method for acquiring handwriting according to an embodiment of the present application.

In one embodiment, the handwriting obtained after rendering the rendering buffer based on bilinear interpolation sampling includes:

Step S171: Perform bilinear interpolation sampling on the SDF texture image to obtain a distance value from each texel point after interpolation sampling to the handwriting axis.

Step S172: In the rendering buffer, after color-filling sampling points whose distance from the handwriting axis is less than or equal to the preset rendering line width, the writing handwriting is obtained.

Render the rendering buffer, perform bilinear interpolation sampling on the SDF texture image, obtain the distance value of each texel point after the interpolation sampling to the handwriting axis, and fill the rendering buffer with a color to match the value of the handwriting axis. The distance value of the handwriting axis is less than or equal to the corresponding point of the preset rendering line width, and the writing handwriting is obtained.

It should be noted that the writing handwriting mentioned in the embodiments of the present application is a special writing handwriting. For example, the starting point, the ending point and the corner of the writing handwriting are all arc shapes, that is, when implementing the present application It was found in the process that: for such a handwriting, the shortest distance from any point on the handwriting to the axis of the handwriting is less than or equal to half of the width of the handwriting. For this reason, the present application fills the rendering buffer with the color to the corresponding point where the distance from the handwriting axis is less than or equal to the preset rendering line width, and the obtained writing handwriting is the starting point of the writing handwriting , end endpoints, and corners are arc shapes.

Referring to FIG. 10, in some examples, the SDF texture image is a rectangular image, so the rendering buffer is also a rectangle, and during rendering, the rendering is usually performed in units of triangles. Therefore, for the rendering buffer The area is also constructed as a rectangle of two triangles for rendering. In one embodiment, when rendering the rendering buffer, the rendering buffer is determined by reading the vertices of two triangles, and the SDF texture image is subjected to bilinear interpolation sampling to obtain each texture after the interpolation sampling. The distance value from the pixel point to the handwriting axis, and then according to the mapping relationship between the rendering buffer and the SDF texture image, fill the color in the rendering buffer until the distance value from the handwriting axis is less than or equal to the preset value Render the corresponding point of the line width to obtain the handwriting.

In some examples, the resolution of the SDF texture buffer, that is, the preset texture resolution may be inconsistent with the resolution of the target buffer, that is, the resolution of the rendering display. When the resolution of the SDF texture buffer is lower , the higher the efficiency of generating SDF texture images, but the lower the accuracy, that is, the generated handwriting is also blurred. When the resolution of the SDF texture buffer is higher, the efficiency of generating SDF texture images is lower, but the accuracy is also higher. , that is, the generated handwriting is clearer. In some examples, the resolution of the SDF texture buffer, that is, the preset texture resolution is smaller than the resolution of the target buffer, that is, the resolution of the rendering display, so as to reduce the amount of calculation and improve the rendering efficiency. Please refer to Figure 10, for the target buffer with a resolution of 1600x512, if the texture resolution of the SDF texture buffer is 50x16, the displayed handwriting is relatively smooth, please refer to Figure 11, the same resolution is 1600x512 In the target buffer, if the texture resolution of the SDF texture buffer is 25×8, the edge of the displayed handwriting will be somewhat distorted, but since the SDF texture graphic of the present application stores the distance value, and adopts double lines Therefore, the displayed handwriting still has good precision, and even if the resolution of the SDF texture buffer, that is, the preset texture resolution is smaller than the resolution of the target buffer, that is, the resolution of the rendering display It also has higher rendering accuracy.

Example 2

The following is an apparatus embodiment of the present application, which can be used to execute the content of the method in Embodiment 1 of the present application. For details not disclosed in the device embodiments of the present application, please refer to the content of the method in Embodiment 1 of the present application.

Please refer to FIG. 12 , which is a schematic block diagram of an apparatus for drawing handwriting according to an embodiment of the present application.

A writing and handwriting drawing device 200 disclosed in the embodiment of the present application includes:

The writing operation receiving module 210 is used for receiving the writing operation on the touch screen;

A handwriting axis acquisition module 220, configured to acquire touch point information corresponding to the writing operation, and acquire the handwriting axis corresponding to the writing operation according to the touch point information;

a target buffer determining module 230, configured to determine a target buffer according to the size of the handwriting axis and a preset rendering line width;

a texture buffer acquiring module 240, configured to perform compression processing on the target buffer according to a preset texture resolution to obtain an SDF texture buffer;

The texture image acquisition module 250 is configured to calculate the shortest distance from the position corresponding to each texel point of the SDF texture buffer in the target buffer to the handwriting axis, and determine the shortest distance as the corresponding the value of the texture pixel point of the SDF texture buffer to obtain the SDF texture image;

a mapping relationship acquisition module 260, configured to allocate a rendering buffer according to the target buffer, and establish a mapping relationship between the rendering buffer and the SDF texture image;

A writing handwriting obtaining module 270, configured to obtain writing handwriting after rendering the rendering buffer based on bilinear interpolation sampling;

The handwriting display module 280 is used for displaying the writing handwriting on the touch screen.

In some examples, the target buffer determining module 230 is configured to determine the target buffer according to the size of the handwriting axis and the preset rendering line width, including: adding the horizontal length of the handwriting axis to The preset rendering line width is obtained by adding the longitudinal length of the handwriting axis to the preset rendering line width to obtain the target buffer. The target buffer is obtained by adding the horizontal length of the handwriting axis to the preset rendering line width, and adding the vertical length of the handwriting axis to the preset rendering line width, so that the handwriting can be rendered The display is rendered completely unobstructed.

Please refer to FIG. 13 , which is a schematic block diagram of a handwriting axis acquisition module according to an embodiment of the present application.

In some examples, the touch point information is a plurality of consecutive sampling points collected by the touch screen according to the writing operation; the handwriting axis acquisition module 220 is configured to obtain touch point information in response to a writing operation on the touch screen, Obtaining the handwriting axis corresponding to the writing operation according to the touch point information includes:

The touch point connection module 221 is used to obtain the touch point connection according to the two adjacent sampling points;

The handwriting axis determination module 222 is configured to obtain the handwriting axis corresponding to the writing operation according to the touch point connection.

Please refer to FIG. 14 , which is a schematic block diagram of a texture image acquisition module according to an embodiment of the present application.

In some examples, the SDF texture buffer includes the number of horizontal texels and the number of vertical texels; the texture image acquisition module 250 includes:

Pixel quantity acquisition module 251, for acquiring the horizontal texel quantity and the vertical texel quantity of the SDF texture buffer;

a texture grid dividing module 252, configured to divide the target buffer into a corresponding number of texture grids according to the number of horizontal texels and the number of vertical texels;

A distance calculation module 253, configured to calculate the shortest distance from the center point of each texture grid in the target buffer zone to the handwriting axis;

The pixel value determination module 254 is configured to determine the shortest distance as the value of the corresponding texture pixel point of the SDF texture buffer to obtain an SDF texture image.

Please refer to FIG. 15 , which is a schematic block diagram of a handwriting acquisition module according to an embodiment of the present application.

In one embodiment, the handwriting acquisition module 270 includes:

The distance obtaining module 271 is configured to perform bilinear interpolation sampling on the SDF texture image to obtain the distance value from each texel point after interpolation sampling to the handwriting axis.

The color-filling module 272 is configured to color-fill sampling points whose distance from the handwriting axis is less than or equal to the preset rendering line width in the rendering buffer to obtain handwriting.

Example 3

The following is a device embodiment of the present application, which can be used to execute the content of the method in Embodiment 1 of the present application. For details not disclosed in the device embodiments of the present application, please refer to the content of the method in Embodiment 1 of the present application.

Please refer to FIG. 16 , the present application also provides an electronic device. The electronic device can be any smart terminal including a touch screen, for example, a computer, a mobile phone, a tablet computer, an interactive tablet, etc. In this embodiment of the present application, The electronic device is an interactive tablet 300, such as an interactive tablet with a large-sized touch screen. The interactive tablet 300 may include: at least one processor 301 , at least one memory 302 , at least one display 303 , at least one network interface 304 , user interface 305 and at least one communication bus 306 .

The display 303 includes a display layer and a touch layer, the display layer is used to display data processed by the processor; the touch layer may include: a capacitive screen, an electromagnetic screen or an infrared screen, etc. Generally speaking , the touch layer can receive a touch operation or a writing operation input by a user through a finger or an input device.

Wherein, the user interface 305 is mainly used to provide an input interface for the user, and obtain the data input by the user. Optionally, the user interface 305 may also include a standard wired interface or a wireless interface.

Wherein, the network interface 304 may optionally include a standard wired interface and a wireless interface (eg, a WI-FI interface).

Wherein, the communication bus 306 is used to realize the connection and communication between these components.

The processor 301 may include one or more processing cores. The processor 301 uses various interfaces and lines to connect various parts of the entire interactive tablet 300, and executes by running or executing the instructions, programs, code sets or instruction sets stored in the memory 302, and calling the data stored in the memory 302. Various functions of the interactive tablet 300 and processing data. Optionally, the processor 301 may adopt at least one of digital signal processing (Digital Signal Processing, DSP), field programmable gate array (Field-Programmable Gate Array, FPGA), and programmable logic array (Programmable Logic Array, PLA). A hardware form is implemented. The processor 301 may integrate one or a combination of a central processing unit (Central Processing Unit, CPU), a graphics processing unit (Graphics Processing Unit, GPU), a modem, and the like. Among them, the CPU mainly handles the operating system, user interface and application programs, etc.; the GPU is used for rendering and drawing the content that needs to be displayed on the display layer; the modem is used for handling wireless communication. It can be understood that, the above-mentioned modem may not be integrated into the processor 301, and is implemented by a single chip.

The memory 302 may include random access memory (Random Access Memory, RAM), or may include read-only memory (Read-Only Memory). Optionally, the memory 302 includes a non-transitory computer-readable storage medium. Memory 302 may be used to store instructions, programs, codes, sets of codes, or sets of instructions. The memory 302 may include a stored program area and a stored data area, wherein the stored program area may store instructions for implementing an operating system, instructions for at least one function (such as a touch function, a sound playback function, an image playback function, etc.), Instructions and the like used to implement the above method embodiments; the storage data area may store the data and the like involved in the above method embodiments. Optionally, the memory 302 may also be at least one storage device located away from the aforementioned processor 301 . As shown in FIG. 16 , the memory 302 as a computer storage medium may include an operating system, a network communication module, and a user.

The processor 301 can be used to call the application program of the response delay of the touch screen stored in the memory 302, and perform the following operations: receiving a writing operation on the touch screen; acquiring touch point information corresponding to the writing operation, according to The touch point information obtains the handwriting axis corresponding to the writing operation; the target buffer is determined according to the size of the handwriting axis and the preset rendering line width; the target buffer is compressed according to the preset texture resolution Process, obtain the SDF texture buffer; calculate the shortest distance from the position corresponding to each texel point of the SDF texture buffer in the target buffer to the handwriting axis, and determine the shortest distance as the corresponding The value of the texture pixel point of the SDF texture buffer is obtained, and the SDF texture image is obtained; the rendering buffer is allocated according to the target buffer, and the mapping relationship between the rendering buffer and the SDF texture image is established; based on bilinear interpolation After sampling and rendering the rendering buffer, writing handwriting is obtained; and the writing handwriting is displayed on the touch screen.

In some examples, the processor 301 may be configured to call the response delay application of the touch screen stored in the memory 302, and execute the determination of the target buffer according to the size of the handwriting axis and the preset rendering line width , including performing the following operations: adding the horizontal length of the handwriting axis to a preset rendering line width, and adding the vertical length of the handwriting axis to the preset rendering line width to obtain the target buffer. The target buffer is obtained by adding the horizontal length of the handwriting axis to the preset rendering line width, and adding the vertical length of the handwriting axis to the preset rendering line width, so that the handwriting can be rendered The display is rendered completely unobstructed.

In some examples, the touch point information is a plurality of consecutive sampling points collected by the touch screen according to the writing operation; the processor 301 may be configured to call the response delay of the touch screen stored in the memory 302 The application program, executing the acquisition of touch point information in response to a writing operation on the touch screen, and acquiring the handwriting axis corresponding to the writing operation according to the touch point information, includes executing: obtaining a touch point connection according to two adjacent sampling points. line; obtain the handwriting axis corresponding to the writing operation according to the connection of the touch points. The touch point connection line is obtained by connecting two adjacent sampling points, thereby realizing the quick and accurate acquisition of the handwriting axis.

In some examples, the SDF texture buffer includes the number of horizontal texels and the number of vertical texels; the processor 301 may be configured to call the application program for the response delay of the touch screen stored in the memory 302, and Perform the following operations: obtain the number of horizontal texture pixels and the number of vertical texture pixels in the SDF texture buffer; divide the target buffer into a corresponding number of pixels according to the number of horizontal texture pixels and the number of vertical texture pixels texture grid; calculate the shortest distance from the center point of each texture grid in the target buffer to the handwriting axis; determine the shortest distance as the value of the texture pixel point of the corresponding SDF texture buffer, Get an SDF texture image. By dividing the target buffer into texture grids corresponding to the SDF texture buffer, and then calculating the shortest distance from the center point of each texture grid to the handwriting axis, the shortest distance is determined as The corresponding value of the texture pixel point of the SDF texture image, so that the distance information of the target buffer under high resolution can be fully preserved. The texel in the SDF texture image records the distance value instead of the color value, so that the image compression and stretching will not greatly affect the display effect.

In one embodiment, the processor 301 may perform the rendering of the rendering buffer based on bilinear interpolation sampling to obtain writing handwriting, and the specific execution includes: performing bilinear interpolation sampling on the SDF texture image to obtain The distance value of each texel point after interpolation sampling to the handwriting axis; in the rendering buffer, after color filling the sampling point whose distance value from the handwriting axis is less than or equal to the preset rendering line width, Get handwriting. Combined with the bilinear interpolation sampling method, after color filling the sampling points whose distance value from the handwriting axis is less than or equal to the preset rendering line width, the handwriting is obtained, which can improve the rendering efficiency and prevent the problem of edge distortion. .

Example 4

The present application also provides a computer-readable storage medium, on which a computer program is stored, the instructions are suitable for being loaded by a processor and executing the method steps of the above-mentioned Embodiment 1, and the execution process can refer to the method shown in the first embodiment. The description is not repeated here. The device where the storage medium is located may be an electronic device such as a personal computer, a notebook computer, a smart phone, and a tablet computer.

For the device embodiments, since they basically correspond to the method embodiments, reference may be made to the partial descriptions of the method embodiments for related parts. The device embodiments described above are schematic, wherein the components described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in a local, or it can be distributed over multiple network elements. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of the present application. Those of ordinary skill in the art can understand and implement it without creative effort.

As will be appreciated by those skilled in the art, the embodiments of the present application may be provided as a method, a system, or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It will be understood that each flow and/or block in the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions selected in one or more of the flowcharts and/or one or more blocks of the block diagrams. These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions An apparatus implements the functions selected in one or more of the flowcharts and/or one or more blocks of the block diagrams.

These computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process such that The instructions provide steps for implementing the functions selected in the flow or blocks of the flowcharts and/or the blocks or blocks of the block diagrams.

In an optional configuration, the computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.

Memory may include non-persistent memory in computer readable media, random access memory (RAM) and/or non-volatile memory in the form of, for example, read only memory (ROM) or flash memory (flash RAM). Memory is an example of a computer-readable medium.

Computer-readable media includes both persistent and non-permanent, removable and non-removable media, and storage of information may be implemented by any method or technology. Information may be computer readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read only memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), Flash Memory or other memory technology, Compact Disc Read Only Memory (CD-ROM), Digital Versatile Disc (DVD) or other optical storage, Magnetic tape cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media, such as modulated data signals and carrier waves.

It should also be noted that the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device comprising a series of elements includes not only those elements, but also Other elements not expressly listed, or which are inherent to such a process, method, article of manufacture, or apparatus are also included. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in the process, method, article of manufacture or apparatus that includes the element.

The above are merely examples of the present application, and are not intended to limit the present application. Various modifications and variations of this application are possible for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the scope of the claims of this application.

Claims

A method for drawing handwriting, comprising the following steps:

Receive the writing operation on the touch screen;

acquiring touch point information corresponding to the writing operation, and acquiring the handwriting axis corresponding to the writing operation according to the touch point information;

Determine the target buffer according to the size of the handwriting axis and the preset rendering line width;

Compress the target buffer according to the preset texture resolution to obtain an SDF texture buffer;

Calculate the shortest distance from the position corresponding to each texel point of the SDF texture buffer in the target buffer to the handwriting axis, and determine the shortest distance as the texture of the corresponding SDF texture buffer The value of the pixel point to obtain the SDF texture image;

Allocate a rendering buffer according to the target buffer, and establish a mapping relationship between the rendering buffer and the SDF texture image;

The handwriting is obtained after rendering the rendering buffer based on bilinear interpolation sampling;

The handwriting is displayed on the touch screen.
The method for drawing handwriting according to claim 1, wherein,

The handwriting obtained after rendering the rendering buffer based on bilinear interpolation sampling includes:

Perform bilinear interpolation sampling on the SDF texture image, and obtain the distance value from each texture pixel point after the interpolation sampling to the handwriting axis;

In the rendering buffer, the handwriting is obtained after color-filling sampling points whose distance value from the handwriting axis is less than or equal to the preset rendering line width.
The method for drawing handwriting according to claim 1, wherein,

The SDF texture buffer includes the number of horizontal texture pixels and the number of vertical texture pixels;

calculating the shortest distance from the position corresponding to each texel point of the SDF texture buffer in the target buffer to the handwriting axis, and determining the shortest distance as the corresponding SDF texture buffer The value of the texel point to obtain the SDF texture image, including:

Obtain the number of horizontal texels and the number of vertical texels of the SDF texture buffer;

Divide the target buffer into a corresponding number of texture grids according to the number of horizontal texels and the number of vertical texels;

Calculate the shortest distance from the center point of each texture grid in the target buffer to the handwriting axis;

The shortest distance is determined as the value of the texture pixel point of the corresponding SDF texture buffer to obtain an SDF texture image.
The method for drawing handwriting according to claim 1, wherein,

The texture resolution is less than the resolution of the target buffer.
The method for drawing handwriting according to claim 1, wherein,

The size of the handwriting axis includes the lateral length of the handwriting axis and the longitudinal length of the handwriting axis;

The determining of the target buffer according to the size of the handwriting axis and the preset rendering line width includes:

The target buffer is obtained by adding the horizontal length of the handwriting axis to the preset rendering line width, and adding the vertical length of the handwriting axis to the preset rendering line width.
The method for drawing handwriting according to claim 1, wherein,

The touch point information is a plurality of continuous sampling points collected by the touch screen according to the writing operation;

The obtaining touch point information in response to a writing operation on the touch screen, and obtaining the handwriting axis corresponding to the writing operation according to the touch point information, includes:

According to the two adjacent sampling points, the touch point connection line is obtained;

According to the touch point connection, the handwriting axis corresponding to the writing operation is obtained.
A writing and handwriting drawing device, comprising:

The writing operation receiving module is used for receiving the writing operation on the touch screen;

a handwriting axis acquisition module, configured to acquire touch point information corresponding to the writing operation, and acquire the handwriting axis corresponding to the writing operation according to the touch point information;

a target buffer determining module, configured to determine a target buffer according to the size of the handwriting axis and a preset rendering line width;

a texture buffer acquisition module, configured to compress the target buffer according to a preset texture resolution to obtain an SDF texture buffer;

The texture image acquisition module is used to calculate the shortest distance from the position corresponding to each texel point of the SDF texture buffer in the target buffer to the handwriting axis, and determine the shortest distance as the corresponding The value of the texture pixel point of the SDF texture buffer is described to obtain the SDF texture image;

a mapping relationship acquisition module, configured to allocate a rendering buffer according to the target buffer, and establish a mapping relationship between the rendering buffer and the SDF texture image;

a writing handwriting acquisition module, used for obtaining writing handwriting after rendering the rendering buffer based on bilinear interpolation sampling;

The handwriting display module is used for displaying the writing handwriting on the touch screen.
The writing and handwriting drawing device according to claim 7, wherein,

The SDF texture buffer includes the number of horizontal texture pixels and the number of vertical texture pixels;

The texture image acquisition module includes:

a pixel number acquisition module, used to acquire the horizontal texture pixel number and the vertical texture pixel number of the SDF texture buffer;

a texture grid dividing module, configured to divide the target buffer into a corresponding number of texture grids according to the number of horizontal texels and the number of vertical texels;

A distance calculation module for calculating the shortest distance from the center point of each texture grid in the target buffer to the handwriting axis;

A pixel value determination module, configured to determine the shortest distance as the value of the corresponding texture pixel point of the SDF texture buffer to obtain an SDF texture image.
The writing and handwriting drawing device according to claim 7, wherein,

The texture resolution is less than the resolution of the target buffer.
An interactive tablet comprising a touch screen, a processor and a memory; wherein the memory stores a computer program, the computer program is adapted to be loaded by the processor and execute the method according to any one of claims 1 to 6 How to draw handwriting.
A computer-readable storage medium on which a computer program is stored, wherein, when the computer program is executed by a processor, the method for drawing handwriting according to any one of claims 1 to 6 is implemented.