JPH09146753A - Method and device for displaying multiwindow - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to simultaneously refer to plural windows even in an information processor provided with a small display screen such as a portable information terminal and to change the degree of overlap of three- dimerisinally arranged windows by simple operation. SOLUTION: In the multiwindow display system for three-dimensionally arranging windows, a Z coordinate calculation/overlap control part 410 calculates the Z coordinate value (z) of an window based upon a volume value. A luminance conversion/synthesis processing part 800 converts the luminance of display colors of respective windows based upon the Z coordinate value (z), synthesizes the luminance-converted display colors of superposed windows and displays the synthesized display color on the display screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-window display method and a multi-window display device, and more particularly to a multi-window system capable of simultaneously processing a plurality of applications on a plurality of windows displayed on the screen. In regard to the display method and its display device, which are suitable for window reference and window switching operations when there are many overlapping windows.

[0002]

2. Description of the Related Art Conventionally, a multi-window system used in a personal computer or a workstation displays a plurality of windows in a multiple manner on a plane. The overlapping order is specified for the windows, and the window above the overlapping order is displayed where the two windows are displayed overlapping, and the window below the overlapping order is hidden by the upper window. Was not done. When changing the stacking order, by clicking a part of the window with a pointing device such as a mouse, the clicked window can be displayed at the top.

Recently, it has been considered to use a three-dimensional display for a user interface. For example, in a menu display of an interactive television, there is a user interface in which a menu is displayed as if it is attached to the side surface of a cylinder and the cylinder is rotated by remote control operation. With this user interface, when the desired menu is displayed in front of the screen, pressing the select button starts the service for that menu.

[0004]

In order to effectively utilize the above-mentioned conventional multi-window system, a display device having a high definition and a large screen is required. For example, in a display device such as a laptop computer or a personal digital assistant, if an attempt is made to secure a sufficient work area for one application, one window occupies the display screen. Therefore, the other windows are hidden behind and you cannot see their contents. Also,
Since the hidden window cannot be clicked directly with an icon, a complicated operation is required to display it on the top surface.

A multi-window system in which windows are three-dimensionally arranged like the menu screen display method is also conceivable. However, window operation is not as simple as menu operation, but is simply three-dimensionally arranged. However, it is necessary to provide an operation system suitable for three-dimensional display. If the display screen is small, the above 3
Even in the three-dimensional menu display, there is a problem that one menu occupies the display screen and it is impossible to refer to a plurality of menus at the same time.

Therefore, the technical problem to be solved by the present invention is to solve the above-mentioned problems of the prior art. The object of the present invention is to provide a small display screen such as a portable information terminal. Even in the information processing device provided, it is possible to refer to a plurality of windows at the same time, and for windows arranged in three dimensions,
An object of the present invention is to provide a multi-window display method capable of changing the overlapping condition of windows by a simple operation and a device having a multi-window display function to which the method is applied.

[0007]

[Means for Solving the Problems] In order to solve the above problems,
In order to achieve the above-mentioned object, the present invention has coordinates (Z coordinate) indicating the depth of the window in a direction perpendicular to the display plane (XY plane) of the window, and displays the window display color in accordance with the value of the Z coordinate. A color converting means for converting, a color synthesizing means for displaying a plurality of windows in an overlapping manner, and a window Z
An input means for changing the value of the coordinate and a calculating means for calculating the value of the Z coordinate of the window based on the value obtained from the input means are provided.

Using the value obtained from the input means, the calculation means calculates the value of the Z coordinate of each window. When displaying windows, the color conversion processing first converts the original color of the object displayed in each window using the Z coordinate value of each window. Where a plurality of windows appear to overlap, the colors displayed in the overlapping windows are combined and displayed by the color combining means.

For example, considering the case where materials on a plurality of OHP devices are displayed in a superimposed manner on one screen, the materials correspond to windows, and the color conversion process corresponds to changing the brightness of each OHP device. The OHP device that displays the material corresponding to the window in the foreground is set to be brightest, and the OHP device corresponding to the window in the back is darkened. The display result of the color synthesizing means gives a visual effect similar to that of a plurality of materials displayed in an overlapping manner on one screen.

As described above, the color converting means and the color synthesizing means make it possible to display that the front window is transparent and the rear window is visible on the Z coordinate axis. It is possible to refer to the contents of. Further, by changing the value of the Z coordinate by the input means, it becomes possible to easily change the order of overlapping the windows.

[0011]

Embodiments of the present invention will be described below. In the window display system according to the present invention, FIG.
As shown in (a) of FIG.
100b, 100c, ...) Are arranged in a rectangular coordinate system defined by the XYZ axes 110 such that the plane of each window 100 is parallel to the XY plane. FIG. 1B is a display example of the window 100 on the display screen 120. In this display example, a projected view of the window 100 on the XY plane is displayed, and a window closer to the front (larger Z coordinate) is displayed with higher density (dark black). Although the display of FIG. 1B is a two-dimensional display, an important point of the present invention is that the display is performed at a density determined by the Z coordinate, and the overlapping portion can be seen through. Whether to display or three-dimensionally display is not an essential issue for the present invention.

When changing the overlapping order of windows, 2
FIG. 2 shows how the windows are displayed. In 200, the window "circle" is displayed on the front surface, and the window "triangle" is displayed on the rear surface and is not displayed. When the Z coordinate of the window is changed, 210, 2
After the display state of 20, only the window “triangle” is displayed in the state of 230. In 210, the window "circle" is in the foreground, but the window "triangle" is moved forward and its contents can be referred to. In 220, the window “triangle” is in the foreground, the window “circle” is in the rear, and is visible through the window “triangle”. In this way, in the state of 210 or 220, 2
It is possible to work while referring to the two windows. Although the rear window is not visible in 200 and 230, it is possible to make the window appear more dim than the rear windows in 210 and 220.

FIG. 3 shows an example of the configuration of an apparatus when the present invention is applied to a portable information terminal. The portable information terminal 300 includes a tablet-integrated display 310 integrally formed with a transparent tablet, an input pen 320, a volume 330 for inputting the value of the Z coordinate of the window, display / non-display of the window, and the like. Button 3 for giving instructions
40 are equipped.

Further, the circuit board 35 of the portable information terminal 300.
0 has the following components. CPU 361
Executes a program stored in the ROM 363 or the RAM 362. The means for implementing the window display function according to the present invention is provided as a program,
It is executed by U361. The RAM 362 stores data of application programs, data necessary for window display, and the like. The VRAM (video memory) 364 is a tablet integrated display 310.
Stores the data displayed in. Display controller 3
65 reads the data in the VRAM 364 and controls the display on the tablet integrated display 310. The tablet control unit 366 is a tablet-integrated display 3
It controls input from the ten tablets and passes the input result to the CPU 361. The volume / button control unit 367 controls the input from the volume 330 and the button 340, and delivers the input result to the CPU 361.

In many mobile information terminals, a card slot of a PC card and a modem are built in, and the circuit board 3
Reference numeral 50 includes a card slot control unit (PC card control unit) 368 and a built-in modem 369.

An example of a multi-window display process by the portable information terminal 300 will be described for a case where the display is monochrome binary display, a case where black and white gradation display is performed, and a case where color display is performed.

<“A”: Processing Method in Monochrome Binary Display> FIG. 4 shows the window management system 400 realized by the CPU 361, the window management data 440 existing in the RAM 362, and the flow of processing by arrows. It is a thing.

First, the window management data 440 will be described. The window management data 440 includes a variable 441 relating to the coordinates in the Z-axis direction, a state 442 indicating whether or not the window can be displayed, a display coordinate 443 and size 444 on the XY plane of the window, and an identifier 445 of an application using the window. Become. The window management data 440 is generated for each window, and the window management data 440 exists for the number of windows.

When the value of the volume 330 changes in FIG. 4, the volume / button control unit 367 issues an interrupt to the CPU 361. Then, the Z coordinate calculation / overlap control unit 410 reads the value of the volume, and the variable 441 (θ)
The value of is updated based on the following formula. θ = θ + v · π (π is the circular constant) Equation (1) Here, it is assumed that the volume value v changes in the range of 0 ≦ v ≦ 1.

Next, for θ calculated by the formula, sin θ
Window management data 440 with a small value
The re-display is instructed in order from the application 450 corresponding to the identifier 445. Application 450
Display processing is performed using a display command provided by the window management system 400. Window management system 40
In the command expansion processing of 0, the command issued from the application 450 is executed to generate bitmap data to be written in the VRAM 364. Shading process 430
Selects a shaded pattern from the value of z determined by the following formula, and z = (sin θ + 1) / 2 ... Formula The result is overwritten on the VRAM 364.

The processing method of the shading processing 430 will be described with reference to FIGS. In FIG. 5, 500 is a halftone pattern, 510 is bit data generated by the command expansion process 420, 530 is bit data read from the VRAM 364, and 550 is bit data generated as a result of the halftone process 430. In this figure, 500,510,5
Reference numerals 30 and 550 are 8-byte memory fragments, and small black squares represent bits to be displayed. The shading process is performed by first shading pattern 500 and bit data 510.
The logical product of is calculated (520). From VRAM 364,
The bit data 530 at the position where the bit data 510 should be written is read, and the bit data 530 and the bit data obtained as a result of the logical product are ORed (54
0). The result is bit data 550, which is written in the same VRAM 364 position as the bit data 530.

The shaded pattern is determined by z in the equation.
An example of a shaded pattern is shown in FIG. 1 ≧ z ≧ 0.875
Then the pattern 600, 0.875> z ≧ 0.75
Then pattern 601, 0.75> z ≧ 0.625
, 602 when 0.625> z ≧ 0.5, 604 when 0.5> z ≧ 0.375, and 605 and 0.25 when 0.375> z ≧ 0.25. A pattern 606 is used when> z ≧ 0.125, and a pattern 607 is used when 0.125> z ≧ 0.

In this embodiment, the effect similar to that of changing the display density of the window is obtained by shading, and the window behind (the Z coordinate value z is small) is thin and the window in front (the Z coordinate is smaller). A window with a larger value z) can be displayed darker, and even if the windows overlap,
Information in the rear window can be displayed in the front window. It should be noted that in the present embodiment, the shading processing 4
Although 30 is described as a program and executed by the CPU 361, it is easy to realize this processing by hardware, and should be realized by hardware when a high-speed display function is required.

<“B”: Processing Method in Display of Black and White Gradation Display> FIG. 7 is a diagram showing a processing method of black and white gradation display. The difference from FIG. 4 is the gradation conversion processing 700.
Only. For example, in the case of 16 gradations, one pixel is represented by 4 bits. This is represented by L (0 ≦ L ≦ 15), and L =
When the display density is 15, the display density is the highest. As a result of the command processing expansion 420, L of each pixel is calculated. The gradation conversion processing 700 changes this L by the following equation,
The value of L obtained by the formula is used as the VRAM 364 corresponding to each pixel.
Write at the position. L = int (L · z) (0 ≦ z ≦ 1) ... where int (x) represents the maximum integer not exceeding x.

In the embodiments described in "a" and "b" above, when the front window is displayed, the VRAM has already been displayed.
The rear display data written in 364 may be overwritten by the front display data, and when viewed in pixel units, only the display data of the front window is displayed. However, in a mobile information terminal or the like, the display of characters and line drawings is overwhelmingly large and the display of the surface is small, so that the effect of referring to the rear window through the front window can be expected.

<“C”: Processing method in color display> The processing method of color display will be described with reference to FIGS.
This will be described with reference to FIG. 8 is different from FIG. 4 only in the luminance conversion / synthesis processing 800. In the luminance conversion / combination process 800, the color data of the pixel output from the command expansion process 420 is converted by the value z of the Z coordinate, combined with the color data stored in the VRAM 364, and written in the VRAM 364.

Reference numeral 900 in FIG. 9 indicates a command expansion process 420.
Is the pixel data of the calculated line segment. A small square corresponds to a pixel, color data to be written in the VRAM 364 is assigned to a black-painted pixel, and a white pixel is VRA.
Indicates that there is no data to write to M364. 910
Indicates a set of pixels on the VRAM 364 corresponding to 900, and black pixels indicate that color data has already been assigned. Color data is represented by 1 byte (8 bits) as indicated by 920 and 930, and 3 is set to R of tristimulus value.
Bits, 3 bits for G, and 2 bits for B are allocated. The display control unit 365 is a VRAM 364.
Color data is read from the display, and the red, green, and blue brightness of the display is controlled by the R, G, and B values. For example, in a liquid crystal display, when the values of R, G, and B are maximum values, they are made to be the same color as the white light with the highest brightness, and in the single colors of red, green, and blue,
The display controller 365 controls the brightness so that the brightness is proportional to the R, G, and B values. Therefore, the color data of C1 is r
1, g1, b1, and the color data of C2 is r2, g2,
When it is b2, the color data corresponding to the color nC1 having the brightness n times that of C1 is n · r1, n · g1, n · b1, and the color data of C3 in which C1 and C2 are mixed is r1 + r.
2, g1 + g2, b1 + b2.

Based on this assumption, the luminance conversion / synthesis processing 80
0 converts the luminance conversion of the pixel color data 920 (r1, g1, b1) output by the command expansion processing 420 into (r1 ′, g1 ′, b1 ′) using the value z of the equation.
(R1 ′, g1 ′, b1 ′) is given by the following equation: r1 ′ = int (z · r1) g1 ′ = int (z · g1) b1 ′ = int (z · b1).

Then, the color data 930 (r2, g2, b2) of the corresponding pixel is read from the VRAM 364, and the color data (r3, g3, b3) given by the following equation is V
Write to RAM364. r3 = r1 ′ + r2 g3 = g1 ′ + g2 b3 = b1 ′ + b2 ... Formula When the values of r3, g3, and b3 exceed the maximum values,
The maximum values are r3, g3 and b3.

According to the present embodiment, the colors of the overlapping windows are combined and displayed by additive color mixture, so that a display effect equivalent to displaying the color sheets on a plurality of OHPs on one screen is displayed. You can expect to get.

FIG. 10 shows an example of another processing method for color display. In the embodiment shown in FIG. 10, the luminance conversion / synthesis processing 800 uses the mask pattern 100 determined by the value z of the expression.
With reference to 0, only the pixels for which writing is permitted by the mask pattern 1000 are written in the VRAM 364. FIG.
Then, with respect to the pixel 900 calculated in the command expansion processing 420, only the pixel corresponding to the black portion of the mask pattern 1000 is written in the VRAM 364 (logical product 101 in the figure).
0 represents processing). As a result, in 1020, only the color data of the pixel corresponding to the black portion is written.

An example of the mask pattern is shown in FIG. In this example, the number of windows is limited to two. When the windows are A and B and the Z coordinate value of the window A is z, the pattern 110 is satisfied when 1 ≧ z ≧ 0.875.
0, 0.875> z ≧ 0.75, pattern 11
01, 0.75> z ≧ 0.625, pattern 1
102, 0.625> pattern 1 when z ≧ 0.5
103, 0.5> z ≧ 0.375, pattern 1
104, 0.375> z ≧ 0.25, pattern 1105; 0.25> z ≧ 0.125, pattern 1106; and 0.125> z ≧ 0, pattern 1
107 are used respectively. The mask patterns of 1100a to 1107a are displayed in the window A and 1100b to 110.
The mask pattern of 7b is applied to the window B, respectively.

The present embodiment has the advantage that the brightness conversion / synthesis processing 800 can be performed very simply and at high speed, but as the number of windows increases, it becomes difficult to design the mask pattern and the effect becomes smaller.

In all of the above-mentioned embodiments, the value of the windows in the Z-axis direction can be changed by the volume 330 of FIG. 3, so that the window overlapping condition can be maintained while holding the portable information terminal 300 with only the left hand. It is possible to perform an operation of changing, and it is possible to provide optimum operability when the mobile information terminal is used while moving.

When a large number of windows are displayed in an overlapping manner, it may be annoying if the information of all windows is displayed in an overlapping manner. There are also windows that do not need to be displayed for the time being. An embodiment that can be controlled so as not to display unnecessary windows will be described with reference to FIGS. 12 and 13.

Reference numeral 1200 in FIG.
Z-coordinate calculation / overlap control processing 410 in FIGS. 4, 7 and 8
Shows the flow of processing of. In step 1201, the value of v of the volume 330 is read from the volume / button control unit 367, the value of the variable θ of 441 is changed based on the formula, and the result is stored in 441 (step 120).
2). In step 1203, the screen of the display is erased, and the processes of steps 1206 and 1207 are repeated in order from the window having the largest sin θ for the number of windows. In step 1206, the status 442 is checked, and if the value is "1", the window is not displayed. For a window whose value in state 442 is "0",
In step 1207, the application corresponding to the window is instructed to perform the redisplay processing.

When the button 340 is pressed, the process 1300 of FIG. 13 is activated. Processing 1300 also calculates Z coordinates
This is a part of the process of the overlap control process 410. Step 1
The window management data 440 is checked at 301,
That is, the window management data 440 of the window with the largest value of sin θ is acquired, and if the value of the state 442 is “1”, it is changed to “0”, and if it is “0”, it is changed to “1” (step 1302).

According to the present embodiment, the windows can be erased with a single button operation, so that only the necessary windows can be displayed in an overlapping manner.

Another embodiment in which the operation of changing the overlapping degree of windows is simplified is shown in FIGS. 14 and 15. In this embodiment, only the frontmost window is displayed. The window management system 1400 of this embodiment shown in FIG.
Is the overlap control process 1 for the window display process.
410 and a command expansion processing 1420 are provided. Window management data 1 for each displayed window
430 exists and manages an XY coordinate 1431 regarding a display position of a window, a size 1433, an identifier 1432 of an application using the window, and the like. Further, it has a pointer column 1440 indicating the location of the window management data 1430 corresponding to each window, and the window corresponding to the window management data 1430 indicated by the pointer 1440a at the head of the pointer column 1440 is displayed.

When the button 340 is pressed, the button control unit 1450 causes an interrupt to the CPU 361 and the overlap control processing 1410 is activated. Reference numeral 1500 in FIG. 15 is a diagram showing a processing flow of the overlap control processing 1410. In step 1501, the arrangement of the pointer column 1440 is changed and the display screen is erased. For example, when n valid pointers exist, the value of the leading pointer 1440a is saved in the temporary work area, and the i-th pointer is moved to the i−1th position (i = 2.
3, ..., N), and finally, the value of the pointer 1440a saved in the work area is stored in the nth position. In step 1502, the application 450 displaying the frontmost window is determined from the identifier 1432, and the application 450 is instructed to re-display. The application 450 issues a display command provided by the window management system 1400, and the command expansion processing 1420 performs VR based on the display command.
Bitmap data for display is generated in the AM364.

According to the present embodiment, by simply adding a button to the conventional portable information terminal, the window can be easily switched with one hand, and the operability of the portable information terminal can be improved.

In the above description, the present invention has been described by taking the portable information terminal using a pen as an example. However, in the case of an information processing apparatus having a keyboard, the volume or button may be replaced by the keyboard key. Needless to say, the same effect as that of the embodiment can be obtained by displaying it as an object on the screen and operating it with a mouse or the like.

[0043]

As described above, according to the present invention, even in an information processing apparatus having a small display screen such as a portable information terminal, it is possible to simultaneously refer to a plurality of overlapping windows, and it is simple. There is an effect that it is possible to realize a multi-window system capable of changing the degree of overlapping of three-dimensionally arranged windows by various operations.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a concept of a window system according to the present invention.

FIG. 2 is a diagram illustrating a change in display state of the window system according to the present invention.

FIG. 3 is a diagram showing a configuration example of a mobile information terminal to which the present invention is applied.

FIG. 4 is a diagram showing an example of a display process for a monochrome binary display device.

FIG. 5 is a diagram illustrating an example of a halftone processing method.

FIG. 6 is a diagram showing an example of a shaded pattern.

FIG. 7 is a diagram illustrating an example of a display process for a display device that displays black and white gradation.

FIG. 8 is a diagram showing an example of a display process on a color display device.

FIG. 9 is a diagram illustrating a luminance conversion / synthesis process by additive color mixing.

FIG. 10 is a diagram illustrating a luminance conversion / synthesis process using a mask pattern.

FIG. 11 is a diagram showing an example of a mask pattern.

FIG. 12 is a flowchart of Z coordinate calculation / overlap processing.

FIG. 13 is a flowchart of a process performed when a button is pressed.

FIG. 14 is a diagram illustrating a process of changing the overlapping degree of windows.

FIG. 15 is a flowchart of an overlap control process.

[Explanation of symbols]

 300 portable information terminal 330 volume 340 button 367 volume / button control unit 400 window management system 410 Z coordinate calculation / overlap control processing 420 command expansion processing 430 halftone processing 440 window management data 700 gradation conversion processing 800 luminance conversion / combination processing 1200 Z Flow of coordinate calculation / overlap control processing

Claims (14)

[Claims] 1. In a multi-window system capable of displaying a plurality of windows on a display and operating a plurality of applications on the windows, when displaying windows arranged in a three-dimensional space on a two-dimensional plane. In addition, when a plurality of windows are overlapped on a two-dimensional plane, the display color of the overlapping portion is determined by synthesizing the display colors of the overlapping windows. 2. The multi-window display method according to claim 1, further comprising means for changing the arrangement of windows in a three-dimensional space. 3. In a multi-window system capable of displaying a plurality of windows on a display and operating a plurality of applications on the windows, the window plane is parallel to the XY plane on an XYZ orthogonal coordinate system. The windows are arranged as described above, and color conversion means for changing the display color of the window based on the value of the Z coordinate of the window and color combining means for synthesizing the display colors of the plurality of windows are provided, and XYZ is performed on the two-dimensional plane. When displaying a window in the coordinate space, the display color is changed by the color conversion means and displayed, and the portion where a plurality of windows are overlapped is displayed after the conversion by the color conversion means for the overlapping windows. A multi-widow characterized in that the display color of the overlapping portion is determined by synthesizing the display colors of Doe display method. 4. The method according to claim 3, further comprising: first input means for changing the value of the Z coordinate of the window, and the two or more windows being displayed based on the input value from the first input means. The multi-window display method is characterized in that it is possible to change the value of the Z coordinate of. 5. The multi-window display method according to claim 4, further comprising a second input means for inputting whether or not each window is to be displayed, and display / non-display of each window can be controlled. 6. The display color according to claim 4, wherein the display color is represented by values r, g, b of tristimulus values R, G, B, and Z.
When the coordinate value is z (0 ≦ z ≦ z _max ), the display color value converted by the color conversion means is r · z / z.
_max , g · z / z _max , b · z / z _max (· is multiplication, /
Is a division), and the display colors r1, g1, b1 and the display color r
When the display color of the combination result of the color combining means of 2, g2, b2 is r1 + r2, g1 + g2, b1 + b2, and the calculation result of the color combining means exceeds the maximum value of R, G, B set by the system. , A multi-window display method characterized by replacing the calculation result with the maximum value. 7. The method according to claim 4 or 5, wherein a plurality of mask patterns for determining whether or not to display a pixel are provided, and instead of the color conversion means and the color composition means,
By providing means for determining display / non-display of pixels in the window based on a mask pattern determined by the Z coordinate of the window, an effect equivalent to that of the color conversion means and the color composition means is provided. Window display device. 8. Information capable of multi-window display, comprising a tablet and a pen as first input means, and a display device and a video memory for storing bitmap data to be displayed on the display as display means. In the processing device, each window is provided with an attribute z indicating the position of the window in the depth direction, and second input means for changing the attribute z is provided so that the display color or display density of the window can be determined based on the value of the attribute z. A multi-window display device characterized by controlling display so that the contents of a plurality of overlapping windows can be referred to while being changed. 9. The display device according to claim 8, wherein the display device is a display device that displays in black and white binary, has a plurality of halftone patterns, and has a small value of the attribute z when displaying a window. A means for generating bitmap data in order from the display data of the window and a logical product of the generated bitmap data and the halftone pattern determined by the value of the attribute z, and the logical sum of the result and the contents of the video memory. And a means for writing to the video memory. 10. The display device according to claim 8, wherein the display device is a display device that performs black and white gradation display, and the attribute z is displayed when a window is displayed.
Means for generating the bitmap data in order from the display data of the small window, and means for changing the gradation data of the pixels of the generated bitmap data based on the value of the attribute z and writing it in the video memory. A multi-window display device having. 11. The display device according to claim 8, wherein the display device is a color display device, and the video memory holds tristimulus values r, g, and b as pixel data, and when the window display is performed. Further, means for changing the tristimulus values r, g, b of each pixel generated as bitmap data based on the value of the attribute z, and the changed tristimulus values and pixel data of the video memory are held. Means for adding tristimulus values and writing to the video memory. 12. The display device according to claim 8, wherein the display device is a color display device, and the video memory holds tristimulus values r, g, and b as pixel data. A plurality of mask patterns for designating whether or not pixel data can be written are provided, and the value of the attribute z is written when the tristimulus values r, g, and b of each pixel generated as bitmap data are written in the window display. A multi-window display device comprising means for writing pixel data in the video memory only when writing is possible with reference to a mask pattern corresponding to. 13. The display device according to claim 8, further comprising a third input means for inputting whether or not to display each window, and display / non-display can be controlled in window units. Multi-window display device. 14. Information capable of multi-window display, comprising a tablet and a pen as first input means, and a display device and a video memory for storing bitmap data to be displayed on the display as display means. The processing device has a second input means for changing the overlapping order of the windows, changes the overlapping order of the windows based on the input from the second input means, and displays the frontmost window by changing the order. A multi-window display device comprising means.