C语言函数大全（i开头）

C语言函数大全（i开头）2010-01-29函数名: imagesize

功能: 返回保存位图像所需的字节数

用法: unsigned far imagesize（int left, int top, int right, int bottom）;

程序例:

#include
#include
#include
#include
#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
", 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）;
}