JP2009198639A - Image display apparatus and scroll control method and scroll control program for image display apparatus, electronic equipment having image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a high speed lateral scroll by means of DMAC without using a highly functional LCD controller. <P>SOLUTION: An image display apparatus includes: a display section; a VRAM; a reduced image forming section which generates reduced image data of size that allows a reduced image to be displayed on a display section from a plurality of image data; the DMA controller that rotates the arrangement of input data and transfers the rotated arrangement of input data based on a control register which instructs to rotate the arrangement of data 90° to the right or left; a scroll buffer including storage areas where an m number of the reduced image data can be disposed in each line with the reduced image data rotated 90° to the right; an operating section that indicates the start position of the scroll buffer to be transferred to the VRAM; a right rotation transfer section that successively transfers reduced image data to the scroll butter by means of the DMA controller whose control register has been set at 90° on the right side; and a left rotation transfer section that transfers a predetermined amount of data to the VRAM from the start position of the scroll butter by means of the DMA controller whose control register has been set at 90° on the left side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image display device, a scroll control method of the image display device, a scroll control program, and an image display device for scrolling and displaying information characters and photographs in the vertical direction (vertical direction) or the horizontal direction (left and right direction). It is related with the provided electronic equipment.

  A high-performance LCD (LCD: Liquid Crystal Display) controller provided in a personal computer or the like has a virtual screen function using a large amount of VRAM (Video Random Access Memory) as shown in Patent Document 1 and Non-Patent Document 1, for example. By using this function, it is possible to scroll and display information characters and photographs vertically (up and down) or horizontally (left and right). For example, to display dozens of photos by scrolling in the horizontal direction, a large amount of VRAM must be allocated to the virtual screen area.

  However, small devices such as printers and digital cameras cannot be equipped with a large amount of VRAM, and only a few virtual screen areas can be secured. Therefore, an image that does not fit in the virtual screen area is displayed by the CPU in the virtual screen area. It must be rewritten while calculating the position, and horizontal scrolling cannot be performed smoothly and at high speed.

  In such small devices, a direct memory access (DMA) controller that can transfer data directly from memory to memory or from memory to peripheral devices without going through the CPU is used to lighten the load on the CPU. The image data of the external memory card can be transferred to the internal VRAM at high speed.

Japanese Patent Laid-Open No. 10-240213 (FIG. 7) Design Wave Magazine 2004 October CQ Publisher (P.41)

  However, in the conventional method, in the case of vertical scrolling, the display can be switched at high speed only by shifting the start address of the DMA controller. However, in horizontal scrolling, the buffer cut from the scroll buffer is temporarily stored in another VRAM. There is a problem that it is necessary to copy the data to the transfer buffer and then to the VRAM, and the display cannot be switched at the same high speed as in vertical scrolling.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A reduced image generating unit that generates reduced image data having a size that can be displayed on the display unit from a plurality of image data stored in an external storage medium, a display unit, a VRAM having a storage area including a display area of the display unit A DMA controller that rotates and transfers the input data array based on the control register that instructs to rotate the data array to the right 90 degrees or the left 90 degrees, and the reduced image data rotated 90 degrees to the right A scroll buffer including a storage area in which m (m is an integer of 3 or more) can be arranged in one column, an operation unit for instructing the start position of the scroll buffer to be transferred to the VRAM, and the control register at 90 degrees to the right A right rotation transfer unit for sequentially transferring the reduced image data to the scroll buffer by the DMA controller set to Including a left rotation transfer unit for a predetermined amount of data from the start position of the scroll buffer by the DMA controller set at 90 degrees to the left is transferred to the VRAM, the image display apparatus, characterized in that.

  According to this configuration, the image data is rotated 90 degrees to the right by the DMA controller and transferred to the scroll buffer, and the image data is rotated 90 degrees to the left from the specified start position of the scroll buffer and transferred to the VRAM. The image data can be smoothly scrolled in the left-right direction.

[Application Example 2]
The image display apparatus according to the above, wherein the scroll buffer is a ring buffer.

  According to this configuration, by configuring the scroll buffer with a ring buffer, it is possible to realize horizontal scrolling with a small capacity even for a large amount of image data.

[Application Example 3]
An electronic apparatus comprising the image display device described above.

  According to this configuration, the image data is rotated 90 degrees to the right by the DMA controller and transferred to the scroll buffer, and the image data is rotated 90 degrees to the left from the specified start position of the scroll buffer and transferred to the VRAM. It is possible to provide an electronic apparatus that can smoothly scroll the image data in the left-right direction.

[Application Example 4]
Reduced image generation step of generating reduced image data having a size that can be displayed on the display unit from a plurality of image data stored in an external storage medium and a VRAM having a display unit, a storage area including a display area of the display unit A DMA controller that rotates and transfers the input data array based on the control register that instructs to rotate the data array to the right 90 degrees or the left 90 degrees, and the reduced image data rotated 90 degrees to the right Scrolling of an image display device including a scroll buffer including a storage area in which m (m is an integer of 3 or more) can be arranged in one column and an operation unit for instructing a start position of the scroll buffer to be transferred to the VRAM In the control method, the reduced image data is sequentially transferred to the scroll bar by the DMA controller in which the control register is set to 90 degrees to the right. A right rotation transfer step for transferring the data to the device, and a left rotation transfer step for transferring a predetermined amount of data from the start position of the scroll buffer to the VRAM by the DMA controller with the control register set to 90 degrees to the left. A scroll control method for an image display device.

  According to this configuration, the image data is rotated 90 degrees to the right by the DMA controller and transferred to the scroll buffer, and the image data is rotated 90 degrees to the left from the specified start position of the scroll buffer and transferred to the VRAM. The image data can be smoothly scrolled in the left-right direction.

[Application Example 5]
Reduced image generation step of generating reduced image data having a size that can be displayed on the display unit from a display unit, a VRAM having a storage area including a display area of the display unit, and a plurality of image data stored in an external storage medium A DMA controller that rotates and transfers the input data array based on the control register that instructs to rotate the data array to the right 90 degrees or the left 90 degrees, and the reduced image data rotated 90 degrees to the right Scroll of an image display device including a scroll buffer including a storage area that can be arranged in m (m is an integer of 3 or more) in one column and an operation unit that indicates a start position of the scroll buffer to be transferred to the VRAM. A control program for sequentially reducing the reduced image data by the DMA controller with the control register set to 90 degrees to the right. A right rotation transfer step for transferring to the roll buffer, and a left rotation transfer step for transferring a predetermined amount of data from the start position of the scroll buffer to the VRAM by the DMA controller with the control register set to 90 degrees to the left. A scroll control program for an image display device.

  According to this configuration, the image data is rotated 90 degrees to the right by the DMA controller and transferred to the scroll buffer, and the image data is rotated 90 degrees to the left from the specified start position of the scroll buffer and transferred to the VRAM. The image data can be smoothly scrolled in the left-right direction.

  Hereinafter, an embodiment of an image display device will be described with reference to the drawings.

(First embodiment)
<Configuration of image display device>
First, the configuration of a printing apparatus that is an electronic apparatus including the image display apparatus according to the first embodiment will be described with reference to FIG. FIG. 1 is a block diagram illustrating a configuration of a printing apparatus including an image display apparatus according to the first embodiment.

  As shown in FIG. 1, the printing apparatus 1000 includes an image display apparatus 100 and a printer controller 300. In FIG. 1, the processing unit and the printing mechanism after the printer controller 300 are omitted for simplification of description.

  The image display apparatus 100 includes a CPU 110, a ROM 120, a RAM 130, an LCD (Liquid Crystal Display) 150 that is a display unit, an LCD controller 140 that controls the LCD 150, an operation unit 160, and a VRAM (Video Random Access Memory) 170. And an interface (I / F) unit 180 for transmitting / receiving data to / from the external storage medium 190 and a DMA (Direct Memory Access) controller 200 are connected to each other via the internal bus 102. .

  The ROM 120 stores a control program 121 including a reduced image generation unit 122, a right rotation transfer unit 124, and a left rotation transfer unit 126, and is executed by the CPU 110. The RAM 130 stores the reduced image data 132 reduced to a size that can be displayed on the LCD 150 from the plurality of image data stored in the external storage medium 190 by the reduced image generation unit 122, and the scroll buffer 134.

  FIG. 2 is a configuration diagram illustrating configurations of a display unit and an operation unit of the printing apparatus. The printing apparatus 1000 includes an LCD 150 and an operation unit 160. A plurality of reduced image data 132 is displayed on the LCD 150 so as to be scrolled in the horizontal direction.

  The operation unit 160 includes a plurality of operation buttons 161 to 164. When the operation button 163 is pressed, the operation unit 160 scrolls the plurality of reduced image data 132 toward the left hand direction, and when the operation button 164 is pressed, the plurality of reduced image data 132 is displayed. By scrolling in the right hand direction and pressing the operation button 161, the currently displayed reduced image data 132 is selected.

<Configuration of DMA controller>
Next, the configuration of the DMA controller will be described with reference to FIG. FIG. 3 is a block diagram showing the configuration of the DMA controller.

  As shown in FIG. 3, the DMA controller 200 includes a control unit 210, a byte counter (Bc) 230, a column counter (Cc) 232, and a row counter connected to the internal bus 102 of FIG. A counter (Rc: Row Counter) 234, a source address (Sa: Source Address) calculator 236, a destination address (Da: Destination Address) calculator 238, a data buffer 240, a register 220, an adder 250, , And a multiplier 252 are mutually connected to the internal bus 201.

  The register 220 stores a control register CR, a source-side column size Cx, a source-side row size Rx, a total number of bytes Tb, a source-side start address S0, and a destination-side start address D0. Yes.

  FIG. 4 is a configuration diagram showing the configuration of the control register. As shown in FIG. 4, the control register CR stores a flag for setting “0: right rotation / 1: left rotation” in the 0th bit b0, and “0: no rotation / 1: rotation” in the first bit b1. A flag for setting “Yes” is stored, and a flag for setting “0: transfer end / 1: transfer start” is stored in the seventh bit b7.

<Operation of DMA controller>
Next, the operation of the DMA controller will be described with reference to FIGS. FIG. 5 is a block diagram for explaining the clockwise rotation operation of the DMA controller. FIG. 6 is a flowchart for explaining the right rotation transfer operation of the DMA controller. FIG. 7 is a block diagram for explaining the left rotation transfer operation of the DMA controller. FIG. 8 is a flowchart for explaining the left rotation transfer operation of the DMA controller.

<Operation of DMA controller clockwise rotation>
First, the right rotation transfer operation (right rotation transfer unit 124) of the DMA controller 200 will be described with reference to FIGS. For simplification of description, the case where the source side column size Cx = 4 and the source side row size Rx = 3 will be described.

  As shown in FIG. 5, the source side array includes source side addresses Sa = 100 to 111, and the destination side array includes destination side addresses Da = 200 to 211. In order to operate the DMA controller 200 so that the source side array is rotated 90 degrees to the right and transferred to the destination side array, the right rotation transfer unit 124 (FIG. 1) transfers the value stored in the register 220 to the source side array. The column size Cx = 4, the source side row size Rx = 3, the total number of bytes Tb = 12, the source side start address S0 = 100, and the destination side start address D0 = 200.

  Next, the right rotation transfer operation of the DMA controller 200 will be described based on the flowchart of FIG.

  First, in step S300, the right rotation transfer unit 124 sets the bit values of the control register CR to b0 = 0, b1 = 1, and b7 = 1 in order to set the right rotation transfer.

  Next, in step S302, the value Bc of the byte counter 230, the value Cc of the column counter 232, and the value Rc of the row counter 234 are reset to zero.

  Next, in step S304, the source address calculation unit 236 calculates the source side address Sa = S0 + Bc.

  Next, in step S306, the destination address calculation unit 238 calculates the destination address Da = (D0 + Rx−1−Rc) + (Rx × Cc).

  In step S308, the data on the source side address Sa is transferred to the destination side address Da.

  Next, in step S310, 1 is added to the value Bc of the byte counter 230 (++ Bc), and it is determined whether or not the value Bc of the byte counter 230 after the addition is equal to or greater than the total number of bytes Tb. If Tb ≦ Bc), the process proceeds to step S316, and if less than the total number of bytes Tb (Tb> Bc), the process proceeds to step S312.

  Next, in step S312, 1 is added to the value Cc of the column counter 232 (++ Cc), and it is determined whether or not the value Cc of the column counter 232 after the addition is greater than or equal to the column size Cx on the source side. If the size is not less than Cx (Cx ≦ Cc), the process proceeds to step S314. If the size is less than the column size Cx on the source side (Cx> Cc), the process proceeds to step S304.

  Next, in step S314, the value Cc of the column counter 232 is reset to 0, 1 is added to the value Rc of the row counter 234 (++ Rc), and the process proceeds to step S304.

  On the other hand, in step S316, in order to set the transfer to end, the right rotation transfer unit 124 sets the bit value of the control register CR to b7 = 0 and ends the process.

  The operation described with reference to the flowchart of FIG. 6 will be described with reference to the source side arrangement of FIG. 5. The data C (0, 0) of the source side address Sa = 100 is represented by the destination side address Da = (200 + 3-1-0) + ( 3 × 0) = 202. Further, the data C (0, 1) of the source side address Sa = 100 + 1 is transferred to the destination side address Da = (200 + 3-1-0) + (3 × 1) = 205. Thereafter, transfer is performed in the same manner, and the source side array of FIG. 5 is transferred to the destination side array by rotating 90 degrees to the right.

<Operation of DMA controller counterclockwise transfer>
Next, the left rotation transfer operation (left rotation transfer unit 126) of the DMA controller 200 will be described with reference to FIGS. For simplification of description, the case where the source side column size Cx = 3 and the source side row size Rx = 4 will be described.

  As shown in FIG. 7, the source side array is configured with source side addresses Sa = 200 to 211, and the destination side array is configured with destination side addresses Da = 300 to 311. In order to operate the DMA controller 200 so that the source side array is rotated 90 degrees to the left and transferred to the destination side array, the left rotation transfer unit 126 (FIG. 1) transfers the value stored in the register 220 to the source side array. The column size Cx = 3, the source side row size Rx = 4, the total number of bytes Tb = 12, the source side start address S0 = 200, and the destination side start address D0 = 300.

  Next, the left rotation transfer operation of the DMA controller 200 will be described based on the flowchart of FIG.

  First, in step S400, in order to set left rotation transfer, the left rotation transfer unit 126 sets each bit value of the control register CR to b0 = 1, b1 = 1, and b7 = 1.

  Next, in step S402, the value Bc of the byte counter 230, the value Cc of the column counter 232, and the value Rc of the row counter 234 are reset to zero.

  Next, in step S404, the source address calculation unit 236 calculates the source side address Sa = S0 + Bc.

  Next, in step S406, the destination address calculation unit 238 calculates the destination address Da = (D0 + Tb−Rx) + Rc− (Rx × Cc).

  In step S408, the data on the source side address Sa is transferred to the destination side address Da.

  Next, in step S410, 1 is added to the value Bc of the byte counter 230 (++ Bc), and it is determined whether or not the value Bc of the byte counter 230 after the addition is equal to or greater than the total number of bytes Tb. If Tb ≦ Bc), the process proceeds to step S416. If less than the total number of bytes Tb (Tb> Bc), the process proceeds to step S412.

  Next, in step S412, 1 is added to the value Cc of the column counter 232 (++ Cc), and it is determined whether or not the value Cc of the column counter 232 after the addition is equal to or larger than the column size Cx on the source side. If the size is greater than or equal to the size Cx (Cx ≦ Cc), the process proceeds to step S414, and if it is less than the column size Cx on the source side (Cx> Cc), the process proceeds to step S404.

  Next, in step S414, the value Cc of the column counter 232 is reset to 0, 1 is added to the value Rc of the row counter 234 (++ Rc), and the process proceeds to step S404.

  On the other hand, in step S416, in order to set the transfer to end, the left rotation transfer unit 126 sets the bit value of the control register CR to b7 = 0 and ends the process.

  The operation described with reference to the flowchart of FIG. 8 will be described with reference to the source side arrangement of FIG. 7. The data C (2, 0) of the source side address Sa = 200 is the destination side address Da = (300 + 12-4) + 0− (4 X0) = 308. Further, the data C (1, 0) of the source side address Sa = 200 + 1 is transferred to the destination side address Da = (300 + 12-4) + 0− (4 × 1) = 304. Thereafter, transfer is performed in the same manner, and the source side array in FIG. 7 is rotated 90 degrees to the left and transferred to the destination side array.

<Configuration of scroll buffer>
Next, the configuration of the scroll buffer will be described with reference to FIGS. FIG. 9 is a configuration diagram showing the configuration of the scroll buffer.

  FIG. 9A shows reduced image data 132 obtained by reducing one of a plurality of image data stored in the external storage medium 190 to a size that can be displayed on the LCD 150 by the reduced image generation unit 122 (FIG. 1). FIG. 9B shows a state in which the reduced image data 132 is rotated 90 degrees right by the right rotation transfer unit 124 and sequentially transferred to the scroll buffer 134. As shown in FIG. 9B, the scroll buffer 134 has a margin more than the width obtained by rotating the reduced image data 132 to the right by 90 degrees, and slightly between the reduced image data 132 adjacent in the vertical direction. I have room. This is to improve the appearance by providing a margin between the reduced image data 132 as shown in the LCD 150 of FIG.

  Data is transferred from the source side start address S0, which is the starting position for transferring from the scroll buffer 134 in FIG. 9B to the VRAM 170 in FIG. The The data transferred to the VRAM 170 is displayed on the LCD 150 in FIG. The source side start address S0 of the scroll buffer 134 is moved by the operation buttons 163 and 164 of the operation unit 160.

  FIG. 10 is a configuration diagram showing an operation when the scroll buffer is configured by a ring buffer. The scroll buffer 134 shown in FIGS. 10A to 10C includes a storage area in which m = 7 can be arranged in one column with the reduced image data 132 rotated 90 degrees to the right. Further, it is assumed that there are 100 pieces of reduced image data 132.

  In FIG. 10A, the source side start address S0 of the scroll buffer 134 is at the position of the first reduced image data 132, and the second to the fourth in the downward direction of the first reduced image data 132 in FIG. Reduced image data 132 are arranged, and the 98th to 100th reduced image data 132 are arranged in the upward direction of the first reduced image data 132.

  10B, the source-side start address S0 of the scroll buffer 134 is at the position of the second reduced image data 132, and the fifth reduced image is used instead of the 98th reduced image data 132 in FIG. Data 132 is arranged. Similarly, when the source side start address S0 of the scroll buffer 134 comes to the position of the third reduced image data 132, the sixth reduced image data 132 instead of the 99th reduced image data 132 in FIG. Is placed.

  10C, the source side start address S0 of the scroll buffer 134 is at the position of the 100th reduced image data 132, and the 97th reduced image is used instead of the fourth reduced image data 132 in FIG. 10A. Data 132 is arranged. Similarly, when the source side start address S0 of the scroll buffer 134 comes to the position of the 99th reduced image data 132, the 96th reduced image data 132 is replaced with the third reduced image data 132 in FIG. Is placed.

<Operation of image display device>
Next, the operation of the image display apparatus will be described with reference to FIGS. FIG. 11 is a flowchart showing the operation of the transfer process to the scroll buffer.

  First, in step S 200, one image data is read from the external storage medium 190 into a predetermined area of the RAM 130 via the I / F unit 180. Here, the expansion according to the image data format is also performed.

  Next, in step S202, the reduced image generation unit 122 generates reduced image data 132 that is reduced from the image data to a size that can be displayed on the LCD 150.

  In step S204, the right rotation transfer unit 124 rotates the reduced image data 132 by 90 degrees to the right and sequentially transfers it to the scroll buffer 134.

  Next, in step S206, it is determined whether or not the necessary number of sheets that can be transferred to the scroll buffer 134 (m = 7 in the case of FIG. 10) has been transferred. If the transfer has been completed, the process proceeds to step S208 and the transfer is completed. If not, the process proceeds to step S200.

  Next, in step S208, the value of the source side start address S0 of the register 220 of the DMA controller 200 is set.

  Next, in step S210, the left rotation transfer unit 126 rotates 90 degrees to the left from the source side start address S0 of the scroll buffer 134, transfers the data to the VRAM 170, and ends the process.

  FIG. 12 is a flowchart showing the operation of the image display apparatus. Here, when the operation button 163 is pressed once, the reduced image data 132 scrolls by 5 dots in the left direction, and when the operation button 164 is pressed once, the reduced image data 132 scrolls by 5 dots in the right direction. explain.

  First, in step S100, transfer processing to the scroll buffer 134 is performed.

  Next, in step S102, it is determined whether or not the operation button 164 has been pressed and an instruction to scroll rightward has been received. If it has come, the process proceeds to step S104, and if not, the process proceeds to step S106.

  Next, in step S104, the source-side column size Cx × 5 is added to the source-side start address S0, and the process proceeds to step S110.

  On the other hand, in step S106, it is determined whether or not the operation button 163 has been pressed and an instruction to scroll leftward has been received. If so, the process proceeds to step S108, and if not, the process proceeds to step S116.

  Next, in step S108, the source side column size Cx × 5 is subtracted from the source side start address S0, and the process proceeds to step S110.

  Next, in step S110, the left rotation transfer unit 126 performs transfer processing from the source side start address S0 of the scroll buffer 134 to the VRAM 170.

  Next, in step S112, the source side start address S0 has reached the next reduced image data 132 (in the case of right scrolling), or the source side start address S0 has reached the previous reduced image data 132 (left). In the case of scrolling), the process proceeds to step S114 if reached, and to step S102 if not reached.

  Next, in step S114, the reduced image data 132 to be transferred next to the scroll buffer 134 is determined, and the process proceeds to step S100.

  On the other hand, in step S116, it is determined whether or not the scrolling is finished. If finished, the process is finished, and if not finished, the process proceeds to step S102.

  According to the present embodiment described above, the following effects can be obtained.

  In the present embodiment, the DMA controller 200 rotates the reduced image data 132 by 90 degrees to the right and transfers it to the scroll buffer 134, and rotates it 90 degrees to the left from the designated start position (source side start address S0) of the scroll buffer 134. Therefore, a plurality of image data can be smoothly scrolled in the left-right direction on the display unit (LCD 150).

  Although the embodiments of the image display device have been described above, the present invention is not limited to these embodiments, and can be implemented in various forms without departing from the scope of the invention. Hereinafter, a modification will be described.

  (Modification 1) Modification 1 of the image display apparatus will be described. In the first embodiment, the case of a printing apparatus as an electronic apparatus has been described. However, the electronic apparatus may be used for a display unit such as an image viewer apparatus or a digital camera.

1 is a block diagram illustrating a configuration of a printing apparatus including an image display device according to a first embodiment. FIG. 3 is a configuration diagram illustrating configurations of a display unit and an operation unit of the printing apparatus. The block diagram which shows the structure of a DMA controller. The block diagram which shows the structure of a control register. The block diagram explaining the operation | movement of right rotation transfer of a DMA controller. The flowchart explaining the operation | movement of right rotation transfer of a DMA controller. The block diagram explaining the operation | movement of left rotation transfer of a DMA controller. 6 is a flowchart for explaining an operation of left rotation transfer of the DMA controller. The block diagram which shows the structure of a scroll buffer. The block diagram which shows the operation | movement at the time of comprising a scroll buffer with a ring buffer. The flowchart which shows the operation | movement of the transfer process to a scroll buffer. The flowchart which shows the operation | movement of operation | movement of an image display apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Image display apparatus, 102 ... Internal bus, 110 ... CPU, 120 ... ROM, 121 ... Control program, 122 ... Reduced image generation part, 124 ... Right rotation transfer part, 126 ... Left rotation transfer part, 130 ... RAM, 132 ... reduced image data, 134 ... scroll buffer, 140 ... LCD controller, 150 ... LCD, 160 ... operation unit, 161-164 ... operation buttons, 170 ... VRAM, 180 ... I / F unit, 190 ... external storage medium, 200 ... DMA controller 201 ... internal bus 210 ... control unit 220 ... register 230 ... byte counter 232 ... column counter 234 ... row counter 236 ... source address calculation unit 238 ... destination address calculation unit 240 ... data Buffer, 250 ... adder, 252 ... multiplier, 300 ... Printer controller, 1000 ... the printing device.

Claims (5)

A display unit;
A VRAM having a storage area including a display area of the display unit;
A reduced image generating unit that generates reduced image data of a size that can be displayed on the display unit from a plurality of image data stored in an external storage medium;
A DMA controller that rotates and transfers an array of input data based on a control register that instructs to rotate the array of data 90 degrees to the right or 90 degrees to the left;
A scroll buffer including a storage area in which m pieces (m is an integer of 3 or more) can be arranged in a row with the reduced image data rotated 90 degrees to the right;
An operation unit for instructing a start position of the scroll buffer to be transferred to the VRAM;
A right rotation transfer unit for sequentially transferring the reduced image data to the scroll buffer by the DMA controller in which the control register is set to 90 degrees to the right;
A left rotation transfer unit for transferring a predetermined amount of data from the start position of the scroll buffer to the VRAM by the DMA controller having the control register set to 90 degrees to the left;
including,
An image display device characterized by that.   2. The image display device according to claim 1, wherein the scroll buffer is a ring buffer.   An electronic apparatus comprising the image display device according to claim 1. A display unit;
A VRAM having a storage area including a display area of the display unit;
A reduced image generation step of generating reduced image data of a size that can be displayed on the display unit from a plurality of image data stored in an external storage medium;
A DMA controller that rotates and transfers an array of input data based on a control register that instructs to rotate the array of data 90 degrees to the right or 90 degrees to the left;
A scroll buffer including a storage area in which m pieces (m is an integer of 3 or more) can be arranged in a row with the reduced image data rotated 90 degrees to the right;
An operation unit for instructing a start position of the scroll buffer to be transferred to the VRAM;
A scroll control method for an image display device including:
A clockwise rotation transfer step of sequentially transferring the reduced image data to the scroll buffer by the DMA controller in which the control register is set to 90 degrees to the right;
A left rotation transfer step of transferring a predetermined amount of data from the start position of the scroll buffer to the VRAM by the DMA controller having the control register set to 90 degrees to the left;
including,
A scroll control method for an image display device. A display unit;
A VRAM having a storage area including a display area of the display unit;
A reduced image generating step for generating reduced image data of a size that can be displayed on the display unit from a plurality of image data stored in an external storage medium;
A DMA controller that rotates and transfers an array of input data based on a control register that instructs to rotate the array of data 90 degrees to the right or 90 degrees to the left;
A scroll buffer including a storage area in which m pieces (m is an integer of 3 or more) can be arranged in a row with the reduced image data rotated 90 degrees to the right;
An operation unit for instructing a start position of the scroll buffer to be transferred to the VRAM;
A scroll control program for an image display device including:
A clockwise rotation transfer step of sequentially transferring the reduced image data to the scroll buffer by the DMA controller in which the control register is set to 90 degrees to the right;
A left rotation transfer step of transferring a predetermined amount of data from the start position of the scroll buffer to the VRAM by the DMA controller having the control register set to 90 degrees to the left;
including,
A scroll control program for an image display device.

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