JPH02171795A - Double buffer controller - Google Patents

Abstract

PURPOSE:To securely change a picture without using a toggle plane by automatically making the contents of frame buffer for writing coincident with the contents of a frame buffer under display and executing next display to a desired window. CONSTITUTION:It is controlled when and which window the change of display is executed in respective windows 62 and 63 plurally existent. When a series of display data are finisheded being written to the frame buffer for reading and the switch request of the frame buffer is generated, an window updated after preceding frame buffer switching is investigated. The contents on the frame buffer presently displayed to the necessary window are copied on the other pair of the windows and even after the frame buffer switching, the display contents of the two pairs of the frame buffers for display and for writing are switched so that the display contents of the rectangular area can not be changed even after frame buffer switching. Thus, a display graphic can be smoothly changed without using the toggle plane.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is applied to a CRT display device. In particular, the present invention relates to a double buffer means used in a CRT for displaying graphics, which can smoothly change the displayed graphics.

In addition, a graphics processing device that defines multiple views on one display screen and displays graphics, and separate independent application programs running on each window, each application program displaying graphics on the window. It is used in a multi-window system where each double buffer is controlled independently.

〔overview〕

The present invention is a double-buffer control means that can smoothly change the displayed image, which automatically matches the contents of the frame buffer being displayed with the contents of the frame buffer for writing, and updates the display to a desired window. By writing the image information and displaying it next time, it is possible to reliably change the image without using the toggle brain.

[Conventional technology]

Conventionally, this type of double buffer control means has one toggle plane in addition to two sets of frame buffers, and by turning on and off each bit of the toggle plane, which content of the corresponding bit of the frame buffer is displayed on the CRT. There are some that allow you to freely control double buffering using a rectangular area on the frame buffer.

[Problem that the invention seeks to solve]

Such conventional double buffer control means has one extra brain (toggle plane), which increases the amount of memory that the system has, and when switching buffers in a rectangular area, the corresponding one on the toggle plane It is necessary to invert the bits of the entire rectangular area, and if the rectangular area is large, there is a drawback that an image in a half-finished state may be momentarily displayed on the CRT without completely completing the inversion of the bits.

SUMMARY OF THE INVENTION The present invention aims to eliminate these drawbacks and provides a double buffer control device that allows smooth changes in displayed graphics without using toggle planes.

[Means for solving problems]

The present invention is coupled to two frame buffers that store image information related to images displayed in a plurality of windows on a screen of a display means, and that the two frame buffers are alternately switched and stored in the frame buffer. In a double buffer control device equipped with switching means for supplying stored image information to the display means, writing image information related to an image to be displayed in a window designated by an operation into each of the two frame buffers, and , a writing means for writing image information related to the window in which the image is updated into a frame buffer that has not given image information to the display means; The present invention is characterized by comprising a transfer means for transferring image information updated at the time of display among related image information from a frame buffer storing image information related to the image being displayed.

[Effect]

For windows defined as not subject to double buffer control, the same display data content is written to both frame buffers so as not to be affected by buffer switching, and for windows defined as subject to double buffer control, Writes the display data to the frame buffer of the selected frame buffer. Each of the multiple windows manages which window the display has been changed to, and when a series of display data has been written to the write frame buffer and a frame buffer switching request occurs, the previous window is Check the windows that have been updated after switching the frame buffer, and copy the contents of the frame buffer currently displayed for the necessary window onto the other set of frame buffers,
Two sets of frame buffers are switched between display and writing so that the display contents of the rectangular area do not change even after frame buffer switching.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment.

As shown in FIG. 1, this embodiment includes an application system 1, a double buffer display control section 2, a first frame buffer 31, a second frame buffer 32,
The double buffer display control section 2 includes a CRT interface 4 and a CRT 5, and the double buffer display control section 2 includes an area definition means 21 that defines a rectangular area to be controlled by the double buffer on the frame buffer; a rectangular area display data writing means 22 for writing display data such as characters or graphics into a rectangular area on a rectangular area on the two frame buffers; The area display management means 23 and the rectangular area display management means 23 at the time of frame buffer switching check the rectangular area in which the content of the currently displayed frame buffer differs from the content of the other frame buffer; In a rectangular area other than the rectangular area that issued a switching request, the display contents will not change even after frame buffer switching, and in a rectangular area where the contents of the two frame buffers are different, the contents of the currently displayed frame buffer will be changed. It is equipped with a copying means 24 for copying to another frame buffer, and a frame buffer switching means 25 for switching frame buffers, and updates the two frame buffers 31 and 32 according to instructions from the copying application system 1, and displays the data on the CRT 5. control.

That is, in this embodiment, the CRT 5 and the CRT ink face 4, which are display means, store image information related to images displayed in a plurality of windows on the screen.
frame buffer switching means 25 which is connected to two frame buffers 31 and 32 and is a switching means which alternately switches between these two frame buffers 31 and 32 to provide the image information stored in the frame buffers to the display means. Furthermore, as a feature of the present invention, image information related to the image displayed in the window specified by the operation is written to each of these two frame buffers 31 and 32, and the image is updated. The display data writing means 22 is a writing means for writing image information related to the window into a frame buffer that does not provide image information to the display means, and the display data writing means 22 is a writing means for writing image information related to the window into a frame buffer that has not given image information to the display means, and the display data writing means 22 is a writing means for writing image information related to a window into a frame buffer that does not give image information to the display means, A display management means 23 which is a transfer means for transferring image information updated at the time of display among the image information related to the image from the frame buffer that stores the image information related to the image being displayed.
and copying means 24.

FIG. 2 is a diagram showing an example in which a plurality of rectangular areas, that is, windows, are defined and displayed on the CRTS.

FIGS. 3 to 8 are diagrams showing changes in the contents of two sets of frame buffers as the graphics on each window are changed. The operation of this embodiment will be explained with reference to FIGS. 2 to 8.

As shown in FIG. 2, three windows 6L 62 and 63 exist on the CRT 5, and each window corresponds to one rectangular area. A rectangular area defined by the overlapping state of windows is not necessarily a rectangular area on the CRTS.

Now, FIG. 3 shows that the storage area 61a,
62a, 63a and 61b, 62b, 6
3b is generated, storage areas 61a and 61b are defined as areas not subject to double buffer control, the same display data is always written, and storage areas 62a and 63
a, 62b, and 63b are areas defined as double buffer control targets, and first, the contents of the first frame buffer 31 are displayed on the CRTS.

FIG. 4 is a diagram showing the contents of the frame buffer when displaying a circle on the window 62.
2 draws a circle in the second frame buffer 32 according to the request, and the display management means 23 recognizes that the contents are different between the two frame buffers, and draws a circle between the two frame buffers in addition to the storage areas 62a and 62b. Since there is no difference, the contents of the second frame buffer 32 are displayed on the CRT 5 by the frame buffer switching means 25 in response to a frame buffer switching request.

FIG. 5 is a diagram showing the contents of the frame buffer when a horizontally oriented cylinder is displayed on the window 63, and the display data writing means 22 draws the horizontally oriented cylinder on the first frame buffer 31 and manages the display. The means 23 recognizes that the storage area 63a has been updated, and since the contents of the storage areas 63a, 63b and 62a, 62b are different, the copying means 24 updates the storage area on the second frame buffer 32 in response to the frame buffer switching request. 62b onto the first frame buffer 31, and the display management means 23 copies the contents of the storage area 62b onto the first frame buffer 31.
Recognizing that the contents of the first frame buffer 2a and the storage area 62b match, the frame buffer switching means 25 switches the frame buffer, and the contents of the first frame buffer 31 are transferred to the CRT.
displayed on S.

Figure 6 shows the cylinder displayed on the window 63 at 45
3 is a diagram showing the contents of the frame buffer when displaying an image rotated by 45 degrees in the second frame buffer 32.
Since a rotated cylinder is drawn and there is no storage area other than storage areas 63a and 63b with different contents between frame buffers, frame buffer switching is executed immediately and the contents of the second frame buffer 32 are displayed on the CRT 5. Ru.

FIG. 7 is a diagram showing the contents of the frame buffer when the cylinder is further rotated by 45 degrees and displayed. The contents are displayed on the CRT5.

FIG. 8 is a diagram showing the contents of the frame buffer when the circle on the window 62 is enlarged twice and displayed. and 63b have different contents between the frame buffers, the contents of the storage area 63a on the first frame buffer 31 are copied onto the second frame buffer 32, and the contents of the second frame buffer 32 are copied to the CRT.
5 will be displayed on the screen.

[Effects of the Invention] As explained above, the present invention defines a plurality of rectangular areas on a frame buffer and can independently control the display of double buffers.
This has the advantage that display contents can be switched immediately in response to a buffer switching request without affecting the display of another view or window.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram showing the configuration of an embodiment of the present invention. Figure 2 is an example of a window displayed on a CRT. FIGS. 3 to 8 are diagrams showing state transitions of two sets of frame buffers. l...Application system, 2...Double buffer display control unit, 4...CRT interface, 5
... CRT, 21... Area definition means, 22... Display data writing means, 23... Display management means, 24...
- Copying means, 25... Frame buffer switching means, 3
1.32...Frame buffer 7.61.62.63.
...Wind, 61a, 61b. 62a, 62b, 63a, 63b...
storage area.

Claims (1)

[Claims] 1. The display unit is connected to two frame buffers that store image information related to images displayed in a plurality of windows on the screen of the display means, and the two frame buffers are alternately switched. In a double buffer control device equipped with a switching means for supplying the image information stored in this frame buffer to the display means, the image information related to the image displayed in the window designated by the operation is transferred to each of these two frame buffers. a writing means for writing image information related to the window in which the image is updated into a frame buffer that does not provide image information to the display means; A double buffer control device comprising a transfer means for transferring image information updated at the time of display out of image information related to the image inside from a frame buffer storing image information related to the image being displayed. .