JPH10172001A - Drawing apparatus, drawing method thereof, and recording medium thereof - Google Patents

Abstract

(57) [Summary] [Problem] To improve the display speed when re-displaying created trajectory data. SOLUTION: Before storing trajectory data of a drawn trajectory in a trajectory data storage unit 14, trajectory data in which the trajectory is hidden by an eraser trajectory in the trajectory data is detected, and code data indicating the trajectory data is detected. The data is stored in the locus data storage unit 14 together with the locus data. When redisplaying,
The trajectory data indicated by the code data is not read, and the trajectory is not drawn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drawing apparatus for storing a trajectory drawn by a pointing device and drawing it on a screen, a drawing method thereof, and a recording medium thereof.

[0002]

2. Description of the Related Art Conventionally, there has been known a drawing apparatus which executes a drawing software program (collectively referred to as a tool) on a personal computer or the like and displays a locus drawn by a pointing device on a display screen. The tools used in such a drawing apparatus include a bitmap tool that sequentially stores color information for all pixels in an image and a draw tool that sequentially stores coordinate information of pixels input by a pointing device. is there.

In the former case, if the number of display pixels and the number of usable colors are the same, the data storage capacity does not change.

[0004] The latter is characterized in that the data storage capacity is small if the number of pixels input by the pointing device is relatively small. Further, since data is stored in the order of input, it is also possible to reverse the order of input and return to the original. Here, the latter image forming apparatus will be described.

[0005] The input unit 11 is a pointing device, and obtains data such as coordinate values designated by a pen or a mouse and pen-up information. The display unit 12 uses a display device such as a liquid crystal display, and displays a drawn locus.

The image processing apparatus 10 can use various computers, and executes a drawing system drawing tool. The drawing tool has a mode switching program (referred to as a mode switching unit) and a program for drawing a trajectory in a memory (referred to as a trajectory drawing unit).

[0007] The mode switching section 13 switches the processing mode and the type of data to be processed when an icon or the like on the screen is instructed. The processing mode includes a pencil mode, an eraser mode, a save mode, a load mode, and the like. In the pencil mode for drawing and the eraser mode for erasing the drawing in these processing modes, the trajectory indicated by the pointing device is drawn on the screen. Here, a series of coordinate strings from the pen down to the pen up of the pointing device is referred to as one locus.

When a save mode in the above processing modes is designated, data such as mode information, coordinate values, and pen-up information are stored in the locus data storage unit 14. Normal,
A RAM or a hard disk storage device is used for the trajectory data storage unit 14. When the load mode in the processing mode is instructed, the trajectory drawing unit 15 reads the data from the trajectory data storage unit 14 and draws a line connecting the coordinates in order on the screen.

FIG. 2 shows an example of a display screen of the image forming apparatus. In FIG. 2, reference numeral 21 denotes a pencil icon indicating a pencil mode, and reference numeral 22 denotes an eraser icon indicating an eraser mode. A save icon 23 indicates a save mode, and a load icon 24 indicates a load mode. An undo icon 25 indicates an undo mode for canceling the previous input locus.

FIG. 2 shows that the pencil icon is instructed and that four trajectories 1, 2, 3, and 4 are drawn in the drawing color (here, black) in the pencil mode. I have.

FIG. 3 shows a state in which the trajectory 2 is completely hidden by the trajectory 5 in the eraser mode from the drawing state of FIG. In the eraser mode, the locus is drawn in the same color as the background color (here, white), so the locus 5 in FIG.
Appears to be erased by the eraser as shown by. In addition, the locus 3 of FIG. 2 also appears to have a part where the locus 5 overlaps disappeared.

As described above, drawing an image by switching between the pencil mode and the eraser mode has the advantage that the same operation feeling as that of an actual pencil and eraser can be obtained, and that it is easy for anyone to use.

When the drawing is completed, the operator designates the save icon 23 and stores the data in the locus data storage unit 14.

FIG. 5 shows an example of the data format of the locus data stored in the locus data storage unit 14. The trajectory data is stored in the order of input. Color information and thickness information
A predetermined value is set when a pencil or eraser icon is selected.

Next, the load icon 24 is designated and FIG.
FIG. 6 shows a drawing procedure in the case of reading out the data from the locus data storage unit 14 and displaying it again.

The drawing processor 10 reads and draws the locus data in the order in which they are stored. Accordingly, the trajectories are drawn in the order of reference numerals 1, 2, 3, 4, and 5 in FIG. As a result, the same display as when the image was saved can be reproduced.

When the operator designates the undo icon 25 in FIG. 2, the trajectory can be canceled in order from the last input locus. By canceling the trajectory 5, a part of the trajectory 2 and the trajectory 3 hidden in the trajectory 5 are displayed.

[0018]

In the conventional drawing tool, in the drawing procedure of FIG. 6, even data that is finally hidden like the trajectory 2 is once drawn, so that it takes extra time. There is. Thus, when a complicated picture is written by frequently switching between the pencil mode and the eraser mode, this extra time is accumulated to redraw the picture, and the locus read from the locus data storage unit 14 is displayed on the screen. It will take a very long time to be displayed on the.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a drawing apparatus, a drawing method, and a recording medium capable of displaying locus data to be redrawn at a high speed.

[0020]

In order to achieve the above object, according to the present invention, trajectory data to be drawn is input, and the input trajectory data is stored in the first storage means in the order of input. According to an instruction for displaying the stored trajectory data, the trajectory data of the storage means is read out in the input order and drawn, and in the drawing device displayed by the display means, the trajectory indicated by the input trajectory data is input later. Determining means for determining whether or not the trajectory is hidden by the trajectory indicated by the other trajectory data, and storing data indicating the trajectory data of the hidden trajectory when a positive determination is obtained as a result of the determination. A second storage unit, and a control unit that controls not to draw the data indicated by the trajectory data of the second storage unit when the trajectory data of the first storage unit is displayed on the display unit. Characterized in that was.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, there is further provided an instruction means for instructing a return of the display, wherein the control means responds to the instruction of the instruction means, and The trajectory not drawn is controlled to be displayed on the display means.

According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the data is stored adjacent to hidden trajectory data.

According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the data is code data for distinguishing the data from the hidden trajectory data.

According to a fifth aspect of the present invention, in the image forming apparatus according to the third aspect, the data includes identification data indicating locus data of another locus whose locus has been deleted.

According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, the other trajectory is an erasure trajectory having the same color as the background.

According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, when the control means displays the locus data of the first storage means on the display means, it also draws the locus for erasure. It is characterized in that control is not performed.

According to an eighth aspect of the present invention, in the image forming apparatus according to the first aspect, the data and the hidden trajectory data are stored in a storage area separate from unhidden trajectory data.

According to a ninth aspect of the present invention, in the image forming apparatus according to the eighth aspect, the data includes identification data indicating locus data of another locus whose locus has been deleted.

According to a tenth aspect of the present invention, in the image forming apparatus according to the ninth aspect, the other trajectory is an erasure trajectory having the same color as the background.

According to an eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect, when the control means displays the locus data of the first storage means on the display means, it also draws the locus for erasure. It is characterized in that control is not performed.

According to a twelfth aspect of the present invention, the trajectory data to be drawn is input, the input trajectory data is stored in the device in the order of input, and the storage means is stored in response to an instruction to display the stored trajectory data. In the drawing method of the drawing apparatus for reading and drawing the locus data of the input order and displaying the locus data,
The image forming apparatus determines whether or not the trajectory indicated by the input trajectory data is hidden by the trajectory indicated by the other input trajectory data, and if an affirmative determination is obtained as a result of the determination, Data indicating the trajectory data of the hidden trajectory is stored in the apparatus, and when displaying the trajectory data, control is performed so that the trajectory data indicated by the data is not drawn.

According to a thirteenth aspect of the present invention, in the image forming method of the image forming apparatus according to the twelfth aspect, it is possible to receive an instruction to return the display, and to control the display so as to display a locus not drawn in accordance with the instruction. Features.

According to a fourteenth aspect of the present invention, in the image forming method according to the twelfth aspect, the data is stored adjacent to hidden locus data.

According to a fifteenth aspect of the present invention, in the drawing method of the drawing device according to the fourteenth aspect, the data is code data for distinguishing from the hidden trajectory data.

According to a sixteenth aspect of the present invention, in the image forming method according to the fourteenth aspect, the data includes identification data indicating locus data of another locus whose locus has been deleted. I do.

According to a seventeenth aspect of the present invention, in the image forming method according to the sixteenth aspect, the other trajectory is an erasure trajectory having the same color as the background.

According to an eighteenth aspect of the present invention, in the drawing method of the drawing apparatus according to the seventeenth aspect, when displaying the trajectory data, control is performed such that the trajectory for erasure is not drawn. .

According to a nineteenth aspect of the present invention, in the image forming method according to the twelfth aspect, the data and the hidden trajectory data are stored in a storage area separate from unhidden trajectory data. I do.

According to a twentieth aspect of the present invention, in the image forming method according to the nineteenth aspect, the data includes identification data indicating locus data of another locus whose locus has been deleted. I do.

According to a twenty-first aspect of the present invention, in the image forming method according to the twentieth aspect, the other trajectory is an erasure trajectory having the same color as the background.

According to a twenty-second aspect of the present invention, in the method of the twenty-first aspect, when displaying the trajectory data, the trajectory for erasure is controlled so as not to be drawn. .

According to a twenty-third aspect of the present invention, the trajectory data to be drawn is input, the input trajectory data is stored in a storage device in the input order, and the storage device is displayed in response to an instruction to display the stored trajectory data. In a drawing device that reads and traces the trajectory data in the input order and displays the data on a display device, a recording medium that stores program code means read and executed, wherein the program code means comprises:
A step of determining whether or not the trajectory indicated by the input trajectory data is hidden by the trajectory indicated by other input trajectory data; and, if a positive determination is obtained as a result of the determination, the hidden Storing the data indicating the locus data of the locus in the storage device; and controlling not to render the locus data indicated by the data when displaying the locus data on the display device. It is characterized by the following.

[0043]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 7 shows a system configuration of the drawing apparatus of the present invention. The same parts as those of the conventional system of FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, a drawing locus data selection unit 17 for selecting drawing data excluding drawing data related to drawing erasing processing, and a drawing trajectory data selecting unit 17 for selecting drawing data related to figure erasing processing Drawing locus data selection unit 17
A software program for operating the function of the locus data overlap determination unit 16 is provided.

Thus, in the present embodiment, it is possible to select and draw only necessary data from the data in the locus data storage unit 14.

FIG. 8 shows an example of a data format according to the present embodiment. The trajectory data is stored in the order of input. As the color information and the thickness information, predetermined values are set in the items of FIG. 8 corresponding to the pencil mode and the eraser mode when the pencil or eraser icon is selected. The difference from the conventional data format of FIG. 5 is that a code indicating that the data is completely hidden by the locus 5 before the data of the locus 2 is entered in the item column 10.
The point is to set it to 0. This setting process will be described later.

FIG. 9 shows a display procedure when the load icon 24 is designated by the input unit 11 to read data from the locus data storage unit 14 and display it again.

The image processing device 20 includes the locus data storage unit 14
Are read out in the order stored in the locus data 1 to 5.
However, since a code indicating that the data is completely hidden by the trajectory 4 is attached before the data of the trajectory 2, the trajectory 3 is drawn according to the next pointer without drawing the trajectory 2. Therefore, the trajectory is drawn in the order of 1, 3, 4, and 5. As a result, the same display as when the image was saved can be reproduced. When the display procedure of FIG. 9 is compared with the display procedure of the conventional example of FIG. 6, although the display result is the same, since the trajectory 2 is not drawn, the drawing can be performed at a correspondingly high speed.

In addition, since the coordinate data of the trajectory 2 is left in the storage unit, if the input of the trajectory 5 is canceled, for example, in the undo mode, the data of the trajectory 5 is deleted and erased in the trajectory 5 By deleting the sign indicating this and the next pointer, the display of the locus 2 can be restored.

FIGS. 10 and 13 show processing procedures of the image processing apparatus 20 for executing such processing. FIG.
The processing procedure of FIG. 13 is stored in the hard disk storage device in the image processing apparatus, and is executed when the pencil mode and the eraser mode are instructed.

FIG. 10 shows a flowchart of a process for determining whether or not a trajectory is completely hidden by another trajectory. This procedure functions as the locus data overlap determination unit 16 in FIG.

It is assumed that the trajectories are numbered from the first in the order of input.

Further, a table is provided on the RAM in the image processing device 20 for storing the numbers of the trajectories drawn at the positions corresponding to the pixel positions on the display screen of the display section 12 (FIG. 11).

The table of FIG. 11 storing the numbers of the trajectories corresponding to the respective pixels represents a partial area of the screen, and the trajectory 2
And that the locus 3 exists. Locus number 0 represents a pixel without a locus. A counter for storing the number of existing pixels is provided in the image processing device 20 for each trajectory.

The table of FIG. 11 corresponds to the drawing state of the area A of FIG. 6, and the table of FIG. 12 corresponds to the drawing state of the area B of FIG. The processing procedure of FIG. 10 will be described with reference to FIGS.

When the operator instructs the eraser mode, the processing procedure of FIG. When the trajectory 5 of FIG. 6 is input by the input unit 11 (step S1), the image processing apparatus 20 sets the matrix position 201 of the table of FIG. 11 corresponding to the first pixel position of the trajectory in the same manner as in the related art. (Step S2).

Next, as a process related to the present invention, the image processing apparatus 20 reads a locus number written at a set matrix position, in this case, a position 201 in FIG. Further, the current set pixel position is written in the coordinate sequence of the locus 5 in FIG. 8 (step S3). In this example, since the locus number is “0”, it is determined that there is no locus at this pixel position, and the image processing device 20 advances the procedure from step S4 to S8. In step S8, the image processing apparatus 20 sets the locus number “5” at the matrix position 201 as shown in FIG.
Write. Next, the image processing apparatus 20 adds 1 to the pixel counter (in this case, the count value is 1, step S10).

The image processing device 20 performs the processing of steps S1 to S9 so as to rewrite the locus number corresponding to the pixel position next to the locus (matrix position 202 in the table).
At this time, since the trajectory number “2” of the set pixel position (also referred to as a target pixel position) is set at the matrix position 202 of the table, it is determined that the set pixel position has a trajectory.
To overwrite the previous pixel position with the new trajectory, the image processing device 20 decrements the count value 1 of the pixel counting counter of the trajectory number "2" (step S5).

When the count value of the pixel counting counter of the pixel number "2" becomes 0, it means that the track has been overwritten by another track, in other words, it has been completely hidden by the other track. Therefore, the image processing apparatus 20 internally stores the hidden track number (“2”) and the track number to be newly drawn (“5”). More specifically, a code indicating that the trajectory 2 has been erased in the trajectory 5 is written in the data area of the trajectory data 2 at the leading position of the trajectory data of the trajectory number 2 in FIG. In the next data area 101, the head storage address (pointer) of the coordinate sequence of the erased next locus number (in this case, “3”) is written (steps S6 → S7).

In this way, when storing all of the trajectory data, the table is rewritten as shown in FIG. 12, and the determination as to whether or not all of the previous trajectory data has been overwritten and stored is repeated and executed.

Each time a trajectory is input, the above-described steps S1 to S11 are repeated.

Thereafter, when storage of the trajectory data is instructed by operating the save icon 23, the image processing apparatus 20 stores the data of FIG. This process may be conventional and will not require detailed description.

When the display of the locus data in the locus data storage unit 14 is instructed by the load icon 24, the image processing apparatus executes the processing procedure of FIG. Image processing device 20
Reads the locus data of FIG. 8 from the beginning, and determines the type of data. Since the first data is a color code, the procedure proceeds in steps S21 → S22 → S23 → S25, and the colors to be drawn and displayed are set. Subsequently, when the thickness code is read, the thickness to be drawn and displayed is set (S27 → S28 → S21-S23 → S2).
5). When the coordinate data of the locus 1 is read, the locus is drawn on the internal memory of the image processing apparatus according to the coordinate data. Further, the image of the drawn locus is displayed on the display unit 12 (step S24). This processing corresponds to the function of the locus drawing unit in FIG.

The above procedure is repeatedly executed, and the trajectory 1
Is completed, the code 100 indicating that the locus 2 has been erased in the locus 5 is read. As a result, the procedure proceeds to steps S21 → S22 → S26, the pointer 101 of the next storage area is read, and the read address (in this case, the coordinate sequence of the locus 3) indicating this pointer is set to the start address. Therefore, all the locus coordinate values of the locus 2 are not read out, and the processing shifts to the drawing and displaying process of the locus 3.

Hereinafter, since the locus data having the erased sign is skipped and read, the display speed is increased as compared with the related art.

In addition, the relocated trajectory data (reference numerals 100 and 101 in FIG. 8) includes information on a trajectory that hides the trajectory,
Since the pointer of the original data position is included, when the hidden track is canceled by the undo, the hidden track can be restored.

In the above description, the case where the trajectory in the pencil mode is erased by the trajectory in the eraser mode has been described. In addition to this, when a plurality of color pencils can be selected, there is a possibility that the locus of a certain color pencil is completely overwritten by overwriting the locus of another color pencil. In that case, the hidden locus can be prevented from being drawn on the same principle as described above.

(Embodiment 2) Embodiment 2 in which a function specific to an eraser is further added will be described.

FIG. 15 shows a state where the trajectory 6 is further drawn in the eraser mode from the drawing state of FIGS.

As a result, the locus 3 in FIGS. 3 and 4 is completely hidden, and is displayed as shown in FIG. Therefore, according to the display method of the first embodiment, the trajectories 2 and 3 are not drawn. The same display results as in FIG. 15 can be obtained without drawing the eraser trajectories 5 and 6. Focusing on this point, the present embodiment detects a portion where the trajectory of the eraser does not overlap other trajectories to be drawn, and does not draw the trajectory of the eraser which does not overlap the trajectory to be drawn. I do.

If the trajectory of the eraser overlaps another trajectory, an affirmative (Y) determination is obtained in step S4 of the flowchart of FIG. 10 when the trajectory is input in the eraser mode. At this time, all the read-out locus numbers> 0 are stored, and after the process for all the locuses is completed in step S11, the eraser mode , That is, a locus erased by a locus having the same color code as the background.

The relevant data of the trajectory detected in this way (including the code indicating that the trajectory has been erased) is shown in FIG.
Locus data group 103 to be redisplayed and used as shown in FIG.
Is moved to a separate area and stored. As a result, the locus data can be read continuously without performing the updating process of the read address by the address pointer for the redisplay, so that the display speed is further increased. It goes without saying that the data of the erased locus is used in the undo process.

In addition, since the number of the trajectory of the eraser is described in reference numeral 104 (see FIG. 14) indicating that the data group has been erased, when redrawing the trajectory, refer to this code data. The image processing device 20 performs data processing so that the locus of the eraser (in this case, locus 1) is not displayed.

As a result, the process of displaying the trajectory of the eraser, which does not need to be displayed, is omitted, and the display speed of the trajectory is further increased.

The following embodiment can be implemented in addition to the above-described embodiment.

1) In the above embodiment, a general-purpose personal computer is assumed as the image processing apparatus, but various information processing apparatuses can be used according to the application such as a microcomputer.

2) The processing procedure for drawing and displaying according to the present invention may be stored in a floppy disk, and the above-described processing procedure may be installed in a storage unit such as a hard disk when used.

3) In the above-described embodiment, each time a locus is input, it is determined whether or not the locus erases the previously input locus. However, the save mode is instructed in this determination process. You may do it sometimes.

[0080]

As described above, as described above, claims 1 and 1
According to the inventions of the inventions 2 and 23, since the trajectory erased by the subsequent trajectory is detected and the trajectory is not displayed again, the amount of trajectory data to be read is reduced, and the display speed is higher than before. Become.

According to the second and thirteenth aspects of the present invention, the operator can see the hidden trajectory that is not displayed by the instruction of the instruction means, if necessary.

According to the third and fourteenth aspects of the present invention, by providing the data indicating the concealment adjacent to the trajectory data of the hidden trajectory, management relating to the trajectory data, for example,
Processing becomes easier in erasing data and the like.

According to the fourth and fifteenth aspects of the present invention, the type of the data can be determined by setting the format of the hidden data different from that of the locus data.

Claims 5, 6, 7, 9, 10, 11, 1
In the inventions of 6, 17, 18, 20, 21, and 22, not only the hidden trajectory but also the hidden trajectory can be determined. Thus, it is possible to prevent the trajectory for erasing from being drawn, and the speed of the redisplay is further increased.

According to the eighth and nineteenth aspects of the present invention, by storing the trajectory data of the hidden trajectory in a separate storage area, the other trajectory data can be read out continuously in the input order, so that the display speed can be further increased. Become.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a system configuration of a conventional example.

FIG. 2 is an explanatory diagram showing a display example of a drawing figure according to a conventional example.

FIG. 3 is an explanatory view showing a display example of a drawing figure according to a conventional example.

FIG. 4 is an explanatory diagram showing a display example of a drawing figure according to a conventional example.

FIG. 5 is an explanatory diagram showing a data format and data contents of a conventional example.

FIG. 6 is an explanatory diagram illustrating a drawing order according to the first embodiment;

FIG. 7 is a block diagram illustrating a system configuration according to the first embodiment;

FIG. 8 is an explanatory diagram showing a data format and data contents according to the first embodiment.

FIG. 9 is an explanatory diagram illustrating a drawing procedure according to the second embodiment.

FIG. 10 is a flowchart illustrating a processing procedure according to the first embodiment;

FIG. 11 is an explanatory diagram showing the contents of a table that stores the number of a currently displayed trajectory.

FIG. 12 is an explanatory diagram showing the contents of a table that stores the number of the currently displayed trajectory.

FIG. 13 is a flowchart showing the contents of the reading of locus data for redisplay and the data processing thereof.

FIG. 14 is an explanatory diagram showing a data format and data contents according to the second embodiment.

FIG. 15 is an explanatory diagram illustrating a display example according to the second embodiment.

FIG. 16 is an explanatory diagram illustrating a display example according to the second embodiment.

[Explanation of symbols]

 10, 20 image processing device 11 input unit 12 display unit 13 mode switching unit 14 trajectory data storage unit 15 trajectory drawing unit 16 trajectory data overlap determination unit

Claims (23)

[Claims] 1. A trajectory data to be drawn is input, and the input trajectory data is stored in a first storage means in an input order.
In accordance with an instruction to display the stored trajectory data, the trajectory data of the storage means is read out and drawn in the input order,
Determining means for determining whether a trajectory indicated by the input trajectory data is hidden by a trajectory indicated by another input trajectory data; and affirmative determination as a result of the determination. If obtained, the second storage means for storing data indicating the locus data of the hidden locus, and the second storage means for displaying the locus data of the first storage means on the display means. Control means for controlling not to draw the locus data indicated by the data of the means. 2. The image forming apparatus according to claim 1, further comprising instruction means for instructing restoration of display, wherein said control means responds to an instruction from said instruction means, and said control means does not draw a trajectory. And controlling the display means to display the image on the display means. 3. The drawing apparatus according to claim 1, wherein said data is stored adjacent to hidden trajectory data. 4. The drawing apparatus according to claim 3, wherein the data is code data for distinguishing from the hidden trajectory data. 5. The drawing apparatus according to claim 3, wherein the data includes identification data indicating trajectory data of another trajectory whose trajectory has been deleted. 6. The drawing apparatus according to claim 5, wherein the other trajectory is an erasing trajectory having the same color as a background. 7. The image forming apparatus according to claim 6, wherein the control unit controls so as not to draw the trajectory for erasure when displaying the trajectory data of the first storage unit on the display unit. A drawing device characterized by the above-mentioned. 8. The drawing apparatus according to claim 1, wherein the data and the hidden trajectory data are stored in a storage area separate from unhidden trajectory data. 9. The drawing apparatus according to claim 8, wherein the data includes identification data indicating trajectory data of another trajectory whose trajectory has been deleted. 10. The drawing device according to claim 9, wherein
The image forming apparatus, wherein the other trajectory is an erasure trajectory having the same color as the background. 11. The image forming apparatus according to claim 10, wherein the control unit controls not to draw the trajectory for erasure when displaying the trajectory data of the first storage unit on the display unit. A drawing device characterized by the above-mentioned. 12. The trajectory data to be drawn is input, the input trajectory data is stored inside the apparatus in the order of input, and the trajectory data of the storage means is stored in accordance with an instruction to display the stored trajectory data. In a drawing method of a drawing device for reading, drawing, and displaying an input order, the drawing device determines whether or not a trajectory indicated by input trajectory data is hidden by a trajectory indicated by another input trajectory data. If a positive determination is obtained as a result of the determination, data indicating the trajectory data of the hidden trajectory is stored in the device, and when displaying the trajectory data, the trajectory data indicated by the data is displayed. A drawing method for a drawing apparatus, comprising: controlling so as not to draw an image. 13. A drawing apparatus according to claim 12, wherein an instruction to return the display is received, and in response to the instruction, control is performed to display a trajectory not drawn. Drawing method. 14. The method according to claim 12, wherein the data is stored adjacent to hidden trajectory data. 15. The method according to claim 14, wherein the data is code data for distinguishing from the hidden track data. 16. The drawing method for a drawing apparatus according to claim 14, wherein the data includes identification data indicating trajectory data of another trajectory whose trajectory has been deleted. Method. 17. The method according to claim 16, wherein the other trajectory is an erasure trajectory having the same color as a background. 18. The drawing method for a drawing apparatus according to claim 17, wherein when displaying the trajectory data, control is performed such that the trajectory for erasure is not drawn. . 19. A drawing method for a drawing apparatus according to claim 12, wherein said data and said hidden trajectory data are stored in a storage area separate from unhidden trajectory data. Method. 20. The drawing method for a drawing device according to claim 19, wherein the data includes identification data indicating trajectory data of another trajectory whose trajectory has been deleted. Method. 21. A method according to claim 20, wherein said other trajectory is an erasure trajectory having the same color as a background. 22. A method according to claim 21, wherein when displaying the trajectory data, the trajectory for erasure is controlled so as not to be drawn. . 23. The trajectory data to be drawn is input, the input trajectory data is stored in a storage device in the order of input, and the trajectory data of the storage device is stored in accordance with an instruction to display the stored trajectory data. In an image forming apparatus which reads out and forms an image in an input order and displays the image on a display device, a recording medium recording program code means to be read and executed, wherein the program code means has a trajectory indicated by the input trajectory data. Deciding whether or not the trajectory is hidden by the trajectory indicated by the other input trajectory data; and, if an affirmative determination is obtained as a result of the determination, storing the data indicating the trajectory data of the hidden trajectory. Storing in a device, and controlling not to draw the locus data indicated by the data when displaying the locus data on the display device. Recording medium of drawing apparatus characterized by comprising a step.