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c:graphics.h:imagesize

imagesize

Syntax of imagesize

#include <graphics.h>
unsigned imagesize(int left, int top, int right, int bottom);
 

Description of imagesize

imagesize determines the size of the memory area required to store a bit
image. If the size required for the selected image is greater than or
equal to 64K - 1 bytes, imagesize returns 0xFFFF (-1).

Example of imagesize

/* imagesize example */
 
#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
 
#define ARROW_SIZE 10
 
void draw_arrow(int x, int y);
 
int main(void)
{
   /* request autodetection */
   int gdriver = DETECT, gmode, errorcode;
   void *arrow;
   int x, y, maxx;
   unsigned int size;
 
   /* initialize graphics and local variables */
   initgraph(&gdriver, &gmode, "");
 
   /* read result of initialization */
   errorcode = graphresult();
   if (errorcode != grOk) {  /* an error occurred */
 
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1);   /* terminate with an error code */
   }
 
   maxx = getmaxx();
   x = 0;
   y = getmaxy() / 2;
 
   /* draw the image to be grabbed */
   draw_arrow(x, y);
 
   /* calculate the size of the image */
   size = imagesize(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE);
 
   /* allocate memory to hold the image */
   arrow = malloc(size);
 
 
   /* grab the image */
   getimage(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE, arrow);
 
   /* repeat until a key is pressed */
   while (!kbhit()) {
/* erase old image */
putimage(x, y-ARROW_SIZE, arrow, XOR_PUT);
x += ARROW_SIZE;
if (x >= maxx)
    x = 0;
 
/* plot new image */
putimage(x, y-ARROW_SIZE, arrow, XOR_PUT);
   }
 
   /* clean up */
   free(arrow);
   closegraph();
   return 0;
}
 
void draw_arrow(int x, int y)
 
{
   /* draw an arrow on the screen */
   moveto(x, y);
   linerel(4*ARROW_SIZE, 0);
   linerel(-2*ARROW_SIZE, -1*ARROW_SIZE);
   linerel(0, 2*ARROW_SIZE);
   linerel(2*ARROW_SIZE, -1*ARROW_SIZE);
}

See also

output of imagesize example

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c/graphics.h/imagesize.txt · Last modified: 2015/05/06 23:06 (external edit)

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