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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <inttypes.h>
#include <X11/Xlib.h>
#include <X11/X.h>
#include <X11/Xutil.h>
#include <assert.h>
static uint64_t calcChkSum(XImage* ximg, int width, int height)
{
assert(ximg);
uint64_t chksum = 0;
unsigned long red_mask = ximg->red_mask;
unsigned long green_mask = ximg->green_mask;
unsigned long blue_mask = ximg->blue_mask;
for (int x = 0; x < width; ++x) {
for (int y = 0; y < height; ++y) {
unsigned long pixel = XGetPixel(ximg, x, y);
unsigned int blue = pixel & blue_mask; /* 0x0000FF */
unsigned int green = pixel & green_mask; /* 0x00FF00 */
unsigned int red = pixel & red_mask; /* 0xFF0000 */
unsigned int rgb_chk = (red | green | blue);
chksum = (chksum << 24) | ( (chksum >> 40) ^ (rgb_chk & 0xFFFFFF) );
}
}
return chksum;
}
static ssize_t calcImgDiff(XImage* xnew, XImage* xold, int width, int height, unsigned int maxdiff)
{
assert(xnew || xold);
unsigned int diff = 0;
for (int x = 0; x < width; ++x) {
for (int y = 0; y < height; ++y) {
unsigned long newpixel = XGetPixel(xnew, x, y);
unsigned long oldpixel = XGetPixel(xold, x, y);
if (newpixel != oldpixel)
diff++;
if (diff >= maxdiff)
return diff;
}
}
return diff;
}
static int xinit(char* disp_name, Display** disp_ptr, Window* root_ptr, int* width_ptr, int* height_ptr)
{
assert(disp_ptr || root_ptr || width_ptr || height_ptr);
*disp_ptr = XOpenDisplay(disp_name);
if (! *disp_ptr)
return 1;
*root_ptr = DefaultRootWindow(*disp_ptr);
XWindowAttributes attr;
if (XGetWindowAttributes(*disp_ptr, *root_ptr, &attr) == 0)
return 1;
*width_ptr = attr.width;
*height_ptr = attr.height;
return 0;
}
static int genChkSum = 0;
static long long maxIter = -1;
static useconds_t sleep_interval = 1 * 1000 * 1000;
static unsigned int maxdiff = 1000;
static unsigned int bounds[4];
static void parseArgs(int argc, char** argv)
{
int opt;
while ((opt = getopt(argc, argv, "cd:m:i:x:y:w:h:")) != -1) {
switch (opt) {
case 'c':
genChkSum = 1;
break;
case 'd':
maxdiff = (unsigned int)atoi(optarg);
break;
case 'm':
maxIter = atoll(optarg);
break;
case 'i':
sleep_interval = atoll(optarg) * 1000;
break;
case 'x':
bounds[0] = (unsigned int)atoi(optarg);
break;
case 'y':
bounds[1] = (unsigned int)atoi(optarg);
break;
case 'w':
bounds[2] = (unsigned int)atoi(optarg);
break;
case 'h':
bounds[3] = (unsigned int)atoi(optarg);
break;
default:
fprintf(stderr, "usage: %s [-c] [-d maxDiff] [-m maxIter] [-i sleepTime in ms] [-x n] [-y n] [-w n] [-h n]\n", argv[0]);
exit(1);
}
}
}
static int doLoopOnce(Display* disp, Window* root, XImage** old)
{
assert(disp || root || old);
XImage* image = XGetImage(disp, *root, bounds[0], bounds[1], bounds[2], bounds[3], AllPlanes, ZPixmap);
if (!image)
return 1;
if (genChkSum != 0) {
printf("ChkSum: %#" PRIx64 "\n", calcChkSum(image, bounds[2], bounds[3]));
}
printf("ImgDif: %llu\n", (long long unsigned int)calcImgDiff(image, *old, bounds[2], bounds[3], maxdiff));
XDestroyImage(*old);
*old = image;
usleep(sleep_interval);
return 0;
}
static void checkBound(unsigned int value, unsigned int max, const char* name)
{
if (value > max) {
printf("Bound check failed for %s: %u > %u\n", name, value, max);
abort();
}
}
int main(int argc, char** argv)
{
Display* disp;
Window root;
int width, height;
if (xinit(NULL, &disp, &root, &width, &height)) {
fprintf(stderr, "%s: xinit failed\n", argv[0]);
abort();
}
printf("X Resolution: %ux%u\n", width, height);
bounds[0] = 0;
bounds[1] = 0;
bounds[2] = width;
bounds[3] = height;
parseArgs(argc, argv);
checkBound(bounds[0], width-1, "-x");
checkBound(bounds[1], height-1, "-y");
checkBound(bounds[2], width-bounds[0], "-w");
checkBound(bounds[3], height-bounds[1], "-h");
printf("X Image Bounds (X,Y,W,H): %u, %u, %u, %u\n", bounds[0], bounds[1], bounds[2], bounds[3]);
XImage* old = XGetImage(disp, root, bounds[0], bounds[1], bounds[2], bounds[3], AllPlanes, ZPixmap);
if (!old) {
fprintf(stderr, "%s: XGetImage failed\n", argv[0]);
abort();
}
if (maxIter < 0) {
while (1) {
if (doLoopOnce(disp, &root, &old) != 0)
break;
}
} else {
for (long long i = 0; i < maxIter; ++i) {
if (doLoopOnce(disp, &root, &old) != 0)
break;
}
}
return 0;
}
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