CN111724454B - Oversized drawing part imaging method and system based on GDI+ and GDAL - Google Patents
Oversized drawing part imaging method and system based on GDI+ and GDAL Download PDFInfo
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- CN111724454B CN111724454B CN202010375768.2A CN202010375768A CN111724454B CN 111724454 B CN111724454 B CN 111724454B CN 202010375768 A CN202010375768 A CN 202010375768A CN 111724454 B CN111724454 B CN 111724454B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T11/00—2D [Two Dimensional] image generation
- G06T11/60—Editing figures and text; Combining figures or text
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F9/00—Arrangements for program control, e.g. control units
- G06F9/06—Arrangements for program control, e.g. control units using stored programs, i.e. using an internal store of processing equipment to receive or retain programs
- G06F9/44—Arrangements for executing specific programs
- G06F9/451—Execution arrangements for user interfaces
Abstract
The invention discloses a method and a system for drawing an oversized drawing based on GDI+ and GDAL, which realize drawing and outputting of the oversized drawing by combining GDI+ and GDAL, wherein the method comprises the following steps: s1: creating a oversized drawing document through GDAL; s2: calculating the number N of dividing strips of the drawing according to the size of the drawing and the memory of the computer, dividing the drawing into N strips of R1, R2 and R3 … Ri … RN, and sequentially executing the steps S3, S4, S5 and S6 respectively; s3: creating a Bitmap object of the Ri strip through GDI+, and creating a Graphics object; s4: calculating and changing the origin of the coordinate system according to the strip sequence number i; s5: drawing graphic contents through Graphics objects; s6: the Bitmap object is written to the drawing document via GDAL. By the method, the ultra-large drawing and outputting can be realized on common computer equipment, and the system is based on the Net Framework and the open source graphic library, does not depend on a third party interface, and can be used in various environments of a client and a server.
Description
Technical Field
The invention relates to the fields of computer graphics, geographic information systems, remote sensing image processing and the like, in particular to a method and a system for drawing and outputting oversized drawing.
Background
GDI+ (Graphics Device Interface plus) is an optimized and expanded graphic device interface based on GDI, can meet the requirements of developers on graphic output, has rich interfaces, and provides a bottom layer method almost required by drawing. However, the gdi+ has the biggest problem, namely, the problem of memory overflow, and the sizes of the images which can be read and written under different x86 and x64 architectures and different memory conditions are different, so that the drawing and output of the GB-level oversized drawing cannot be satisfied.
GDAL (Geospatial Data Abstraction Library) is an open source geospatial data abstract library under the X/MIT permission protocol, and GDAL supports the reading and writing of image data in various formats, and is particularly widely applied in the field of remote sensing image processing. However, the GDAL only provides the operations of reading and writing image data, which are based on byte arrays, and currently does not provide a graphics rendering interface similar to gdi+, which cannot meet the drawing requirements of the drawing.
Disclosure of Invention
The invention mainly solves the technical problem of providing a method and a system for drawing oversized drawing based on GDI+ and GDAL, and can provide a quick, efficient and GB-level drawing and outputting method for developers.
In order to solve the technical problems, the invention adopts a technical scheme that: a method and system for oversized drawing based on GDI+ and GDAL is provided. Comprising the following steps.
S1: oversized drawing documents are created by GDAL.
S2: according to the size of the drawing and the memory of the computer, calculating the number N of the dividing strips of the drawing, dividing the drawing into R 1 、R 2 、R 3 …R i …R N N stripes are added, and the steps S3, S4, S5 and S6 are respectively executed in sequence.
S3: creation of R by GDI + i The Bitmap object of the strip and creates Graphics object.
S4: and calculating and changing the origin of the coordinate system according to the strip sequence number i.
S5: drawing graphic contents through Graphics objects.
S6: the Bitmap object is written to the drawing document via GDAL.
The beneficial effects of the invention are as follows: the invention discloses a method and a system for drawing oversized drawing based on GDI+ and GDAL, which can provide a quick, efficient and GB-level drawing and outputting method for developers by combining GDI+ and GDAL, is based on a Net Framework and an open source graphic library, does not depend on a third party interface, and can be used in various environments of a client and a server.
Drawings
Fig. 1 is a schematic diagram.
Fig. 2 is an overall flowchart.
Fig. 3 is a sub-flowchart of S3.
Fig. 4 is a sub-flowchart of S5.
Detailed Description
The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making clear and defining the scope of the present invention.
As shown in fig. 1, 2, 3 and 4, an embodiment of the present invention provides a gdi+ and GDAL-based oversized drawing method, which includes the following steps.
S1: oversized drawing documents are created by GDAL. In order to read and write oversized drawing documents conveniently, a BigImageWriter object is packaged, two constructors are provided, blank drawing documents can be newly built, or existing drawing documents can be opened, the existing drawing documents are read through readBytes and readImage by means of packaging ReadBytes, writeBytes, readImage, writeImage, dispose and the like, drawn Bitmap results are written through the WriteBytes and the WriteImage, and resources are released through Dispose.
S2: according to the size of the drawing and the memory of the computer, calculating the number N of the dividing strips of the drawing, dividing the drawing into R 1 、R 2 、R 3 …R i …R N N stripes are added, and the steps S3, S4, S5 and S6 are respectively executed in sequence.
S3: creation of R by GDI + i The Bitmap object of the strip and creates Graphics object. The Bitmap object of the Ri band needs to output the creating mode of the drawing document according to step S1, that is, create a blank Bitmap object, or read from the existing graphic document to obtain the Bitmap object. Blank Bitmap objects can be created directly by gdi+. The bitimagewriter.readimage may be invoked to read a Bitmap object from an existing graphic document, including the following sub-steps.
S31: according to the rectangular range of the current drawn strip, reading byte arrays of 1, 2, 3 and 4 wave bands from the existing graphic document through GDAL, wherein the byte arrays respectively correspond to 4 channels of a (transparency), r (red), g (green) and b (blue), and if no transparency channel exists, the wave bands of 1, 2 and 3 respectively correspond to r (red), g (green) and b (blue).
S32: creating a Bitmap object according to the rectangular range of the current drawn stripe, and then writing the byte array read in the S31 into the Bitmap object through Bitmap, lockBits and Marshal.
S4: and calculating and changing the origin of the coordinate system according to the strip sequence number i. Defining width as the width of the drawing, wherein the origin xoff=0 and yoff=i of the coordinate system are the width; the origin of the coordinate system is reset and set by two methods of graphics.
S5: drawing graphical content through Graphics objects includes the following sub-steps.
S51: based on GDI+ packaging of graphic objects such as straight lines, broken lines, polygons, rectangles, circles, pictures, characters and the like, the method specifically comprises ShapeObject, backColorShape, straightLineShape, polylineShape, polygonShape, rectangleShape, circleShape, imageShape, stringTextShape and the like, and coordinates of the graphics, parameters such as a Brush Pen, a Brush, a Font, an alignment mode StringFormat and the like are defined in the objects, wherein the shape object is a base class of other classes.
S52: according to the size of the image and the graphic content, the world coordinates are converted into image coordinates, and the graphic objects are sequentially added to the collection shape list according to the graphic objects defined in the step S51.
S53: and (5) cycling the Shape list set, and combining DrawLine, drawLines, drawRectangle, drawRectangles, drawPolygon, fillPolygon, fillRectangle, fillRectangles, drawString, drawImage and other basic methods for calling Graphics according to the Shape type to draw the Graphics.
S6: the Bitmap object is written to the drawing document via GDAL. The specific method comprises the following steps: converting the Bitmap object into a byte array through Bitmap, lockBits and Marshal.copy to obtain an RGBytesObject object, and then writing data in the RGBytesObject object into a map document through GDAL.
The foregoing description is only illustrative of the present invention and is not intended to limit the scope of the invention, and all equivalent structures or equivalent processes or direct or indirect application in other related technical fields are included in the scope of the present invention.
Claims (5)
1. The GDI+ and GDAL-based oversized drawing method and system are characterized in that the GDI+ and GDAL-based oversized drawing method comprises the following steps:
s1: creating a oversized drawing document through GDAL;
s2: calculating the number N of dividing strips of the drawing according to the size of the drawing and the memory of the computer, dividing the drawing into N strips of R1, R2 and R3 … Ri … RN, and sequentially executing the steps S3, S4, S5 and S6 respectively;
s3: creating a Bitmap object of the Ri strip through GDI+, and creating a Graphics object;
s4: calculating and changing the origin of the coordinate system according to the strip sequence number i;
s5: drawing graphic contents through Graphics objects;
s6: writing the Bitmap object into the map document through GDAL;
in step S3, the Bitmap object of the Ri band needs to output the creating manner of the drawing document according to step S1, that is, create a blank Bitmap object, or read from the existing graphic document to obtain the Bitmap object, which includes the following steps:
s31: according to the rectangular range, reading byte arrays of 4 channels of transparency, red, green and blue through GDAL, wherein the transparency channels can be empty;
s32: converting the byte array into a Bitmap object through bitmap.lockbits and Marshall.copy;
in step S6, converting the Bitmap object into a byte array through the Bitmap, lockbits and Marshall, obtaining an RGBytesObject object, and then writing the data in the RGBytesObject object into the map document through the GDAL.
2. The method according to claim 1, wherein in step S1, the drawing document supports three graphic formats of tif, img and png, and a blank graphic document can be newly created or created from an existing graphic document, and the drawing document supports a size of 2GB or more.
3. The method according to claim 1, wherein said step S5 comprises the sub-steps of:
s51: based on GDI+ packaging of graphic objects such as straight lines, broken lines, polygons, rectangles, circles, pictures, characters and the like, the graphic objects comprise ShapeObject, backColorShape, straightLineShape, polylineShape, polygonShape, rectangleShape, circleShape, imageShape, stringTextShape and the like, and parameters such as coordinates, colors, widths, alignment modes and the like of the graphics are defined in the objects, wherein the shape object is a base class of other classes;
s52: converting world coordinates into image coordinates according to the size of the formed image and the graphic content, and sequentially adding the graphic objects to a set shape list according to the graphic objects defined in the step S51;
s53: and (5) cycling the Shape list set, and combining DrawLine, drawLines, drawRectangle, drawRectangles, drawPolygon, fillPolygon, fillRectangle, fillRectangles, drawString, drawImage and other basic methods for calling Graphics according to the Shape type to draw the Graphics.
4. The method of claim 1, wherein the RGBBytesObject object includes 5 attributes of ABand, RBand, GBand, BBand, opacity, wherein ABand, RBand, GBand, BBand is a byte array of 4 band channels of transparency, red, green, and blue, and wherein Opacity is superimposed transparency.
5. The method of claim 4, wherein the transparency of the transparency is the transparency of the overall overlay of the currently drawn graphic on an ABand basis, and the transparency is calculated by blending with the ABand channel during the drawing, mainly to achieve the semitransparent overlay effect between the graphic objects.
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| CN202010375768.2A CN111724454B (en) | 2020-05-07 | 2020-05-07 | Oversized drawing part imaging method and system based on GDI+ and GDAL |
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| CN111724454B true CN111724454B (en) | 2023-09-19 |
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| US8176096B2 (en) * | 2008-12-18 | 2012-05-08 | Microsoft Corporation | Data visualization interactivity architecture |
| WO2015112263A2 (en) * | 2013-12-04 | 2015-07-30 | Urthecast Corp. | Systems and methods for processing distributing earth observation images |
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| CN102651138A (en) * | 2012-04-10 | 2012-08-29 | 西安理工大学 | JPEG picture mosaicing-based oversize picture synthesis method |
| CN106204734A (en) * | 2015-04-30 | 2016-12-07 | 浙江宇视科技有限公司 | The map integrated based on multi-source map generates method and device |
| US10282821B1 (en) * | 2015-08-27 | 2019-05-07 | Descartes Labs, Inc. | Observational data processing and analysis |
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