JPH01155429A - Multiwindow display system - Google Patents

Abstract

PURPOSE:To accelerate processing speed as the whole of a system by performing memory access to an image memory and the memory access for display to a display memory, and permitting access to both memories only when data is transferred. CONSTITUTION:When plotting on the image memory 1 is completed or the content of a window information storage means 4 is updated, a data transfer indication signal line 100 becomes active. As a result, a data transfer means 3 performs data transfer from the memory 1 to the display memory 2 in sequence of the content of a rectangular area with lower display priority order sequentially based on the content of the storage means 4. Therefore, most of time in the memory 1 can be used for a plotting cycle, and a cycle is switched to a transfer cycle only when the indication signal 100 becomes active. Since the null time of the display memory 2 for the memory 1 is obtained in a display cycle period, the period can be also used for a plotting processing from a host. Therefore, the waiting of a host side for the plotting processing occurs only in the transfer cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to multi-window display in a digital drawing device using a raster scan type display.

[Conventional technology]

In recent years, there has been an increase in applications in which a single screen is used to perform multiple tasks, or to perform a single task while simultaneously referring to multiple pieces of information. Therefore, multi-window display, in which multiple screens are displayed in a superimposed manner on one screen, has become important.

The conventional method will be explained below with reference to FIG.

A drawing area for drawing and a display area for screen display are set on an image memory that stores drawing data in the form of bit images. The display side reads one memory of this display area in accordance with the scanning of the screen and displays the stored image as it is. Therefore, when the contents of the display area are rewritten, they will be displayed as they are on the screen.

Now, let us consider a case where the contents of three rectangular areas A, B, and C defined in the drawing area on the image memory are superimposed and displayed on the screen as shown in FIG. 4.

Drawing from the host side is performed only for each rectangular area of A, B%C of the drawing area. Then, areas A, area B, and each rectangular area are transferred to the display area in order from the area with the lowest overlap (in this case, area C) in an overlapping manner to the display area.

Then, information on the overlapping rectangular areas is stored in the display area, and this information is displayed as is on the screen, allowing multi-window display.

However, in such a method, two processes are performed for the same image memory: drawing processing related to drawing from the host side and transfer from the drawing area to the display area, and display processing that reads and displays the contents of the memory in the display area. It must be made. Therefore, in order to efficiently perform drawing and display processing,
As shown in FIG. 5, it is common to divide the memory cycle into a drawing cycle and a display cycle, and perform these cycles alternately. This is called the cycle steal method.

[Problem that the invention seeks to solve]

In the conventional multi-window display method described above, whenever the contents of each rectangular area set in the drawing area on the image memory are rewritten or the display position is changed, the contents of each rectangular area are transferred to the display area. It is necessary to re-transfer it to . This transfer processing time becomes very large in proportion to the number and size of windows.

Transfer processing for image memory accessed in a cycle-stealing manner must be performed during a drawing cycle. However, it is also necessary to perform drawing processing from the host side to each of the rectangular areas A and B%C within the same drawing cycle.

Therefore, as the transfer processing time increases, the time available for original drawing from the host side to each rectangular area decreases. In other words, from the host side, the drawing process has to wait, which has the disadvantage of slowing down the processing speed of the entire system.

[Differences between the invention and the prior art]

According to the method of the present invention, a drawing memory (image memory)
By having an independent display memory (display memory), drawing processing and display processing can be considered separately. In other words, no display processing is performed on the image memory, and no drawing is performed on the display memory. Therefore, the drawing memory does not need to be cycle-stealed and is not accessed every time the screen is scanned. Also,
Even if the display memory uses the cycle steal method,
All of the drawing cycles can be used for transfer.

What is common to both is the transfer processing between the two, but this processing does not need to be performed every time the display scans one screen, and can be performed as needed, so it does not affect the drawing processing or display processing. becomes less.

[Means for solving problems]

A digital drawing device using a raster scan type graphic display, in which data in multiple rectangular areas set on an image memory that stores drawn image data as bit images is superimposed and displayed on a single screen. , a display memory independent of the image memory; a window information storage means for storing the position of each rectangular area on the image memory and the display memory; and a priority order when displaying; data transfer means for creating image information identical to that displayed on the screen while transferring data according to the contents of the window information storage means, and there has been a change in the contents of the image memory or the contents of the storage means; and a data transfer instruction signal line for instructing the data transfer means to transfer data, memory access for drawing is performed only to the image memory, and memory access for display is performed to the display memory. By making it so that both memories are accessed only during transfer, the processing time for drawing will be reduced even if the rectangular areas to be displayed overlapping become larger or larger in number. To obtain a multi-window display method which is characterized in that such a problem does not occur.

[Example 1] Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing main components in a first embodiment of the present invention. In the figure, 1 is an image memory that stores drawing data, 2 is a display memory that stores data of the same image as that displayed on the display, 3 is a data transfer means that transfers data from the image memory 1 to the display memory 2, 4 is each rectangular area information set on the image memory 1, position information for transferring them to the display memory 2,
100 is a data transfer instruction signal line for instructing the data transfer means 3 to transfer data; 110 to 115;
is a data bus signal line.

FIG. 2 is a diagram showing the timing of memory access to each of the image memory 1 and display memory 2 in the first embodiment.

Here, the operation of the first embodiment will be explained with reference to the above drawings.

Drawing is performed for each rectangular area set on the image memory 1. Furthermore, when changing the size or display position of each rectangular area, the contents of the rectangular area information and display position information are rewritten in the window information storage means 4.

The data transfer instruction signal line 100 is made active when drawing on the image memory 1 is completed or when the contents of the window information storage means 4 are updated. When the data transfer instruction signal line 100 becomes active, the data transfer means 3 transfers data from the image memory 1 to the display memory 2 in order from the contents of the rectangular area with the lowest display priority based on the contents of the window information storage means 4. conduct.

With this configuration, as shown in FIG. 2, the image memory 1 can use most of the time as a drawing cycle, and can only use the transfer cycle when the data transfer instruction signal 100 becomes active. Become.

The display memory 2 alternately performs transfer processing and display processing using a cycle steal method. The image memory 1 repeats this cycle even when it is not a transfer cycle, and the data transfer means 3 performs the transfer according to this timing when transferring from the image memory 1 to the display memory 2. Furthermore, since the cycle period during which the display memory 2 displays is free time for the image memory 1, that period can also be used for drawing processing from the host side. Therefore, the host side is forced to wait for drawing processing only during the transfer cycle.

[Embodiment 2] Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a block diagram showing main components in a second embodiment of the present invention. Most of the components are the same as those in the first embodiment described above, but the difference is that all the windows instruct the data transfer means 3 to transfer data of all rectangular areas defined on the image memory 1. This is due to the addition of a transfer instruction signal line 101 and a drawing window designation signal line 102 that indicates which rectangular area's contents are changed when the contents of the image memory 1 are changed.

The data transfer means 3 which operates differently from the first embodiment will be described below.

The all-window transfer instruction signal line 101 is activated only when there is a change in the display position information of the rectangular area stored in the window information storage means.

Also, when drawing is performed in the image memory 1, the drawing window designation signal line 10 indicates which rectangular area was drawn.
Specify by 2. When the data transfer instruction signal 100 becomes active, the data transfer means 3 transfers data as follows. First, when the all-window transfer instruction signal 101 is active, all rectangular areas are transferred in order from the rectangular area with the lowest priority, as in the first embodiment. When the all-window transfer instruction signal 101 is not active, only the rectangular area with a higher priority than the rectangular area specified by the drawing window designation signal line 102 is transferred while referring to the window information storage means 4.

By operating the transfer means 3 in this manner, unnecessary area transfers can be eliminated and the time required for transfer processing can be reduced.

〔Effect of the invention〕

As described above, according to the method of the present invention, conventionally, drawing processing from the host side, transfer processing for forming multi-windows, and display processing for reading and displaying the contents of the memory in the display area were performed. By having a display memory independent of the image memory, drawing processing is performed on the image memory, display processing is performed on the display memory, and both memories are accessed only when performing transfer. By doing so, the processing time for drawing from the host side is not affected by the processing time for display. Therefore, more time can be used for drawing, so the overall system The processing speed can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing main components in a first embodiment of the present invention. Figure 2 shows the memory and display memory for each of the image memory and display memory in the first embodiment.
A diagram showing the timing of access, FIG. 3 is the second embodiment of the present invention.
FIG. 4 is a diagram showing a conventional example, and FIG. 5 is a diagram showing the timing of accessing the image memory in the conventional example. 1... Image memory, 2... Display memory, 3... Data transfer means, 4... Win F information storage means, 100... . . . Data transfer instruction signal line, 101 . . . All F win transfer instruction signal lines, 102 . . . Drawing window specification signal line,
110-115...Data bus signal lines. Agent Patent Attorney Uchihara Otoman 1st Part Z Part 3 354th

Claims (1)

[Claims] A digital drawing device using a raster scan type graphic display, which superimposes data in a plurality of rectangular areas set on an image memory that stores drawn image data in the form of bit images to create a single image. In the on-screen display method, a display memory independent of the image memory, a window information storage means for storing the position of each rectangular area on the image memory and the display memory and the priority order when displaying; data transfer means for creating image information identical to that displayed on the screen while transferring data from an image memory to the display memory according to the contents of the window information storage means, the contents of the image memory and the contents of the storage means; a data transfer instruction signal line that instructs the data transfer means to transfer data when there is a change in the data transfer means; memory access for drawing is performed only to the image memory; is performed only on the display memory, and both memories are accessed only during transfer.