C

#include <stdlib.h>#include <stdio.h>#include <unistd.h>#include <X11/Xlib.h>#include <X11/keysymdef.h>#include <X11/extensions/Xrender.h>#define KERNEL_SIZE 5intmain (int argc,	  char** argv){	Display* pDisplay = NULL;	XEvent event;	Bool bKeepGoing = True;	Bool bGotEvent = False;	int iEventBase;	int iErrorBase;	int iMajorVersion;	int iMinorVersion;	XSetWindowAttributes values;	Window window;	XRenderPictFormat* pPictFormat = NULL;	XRenderPictureAttributes pictAttribs;	XRenderColor colorBlue = {0, 0, 255, 127};	Picture picture;	XFixed aiConvolutionKernel[KERNEL_SIZE] = {0, 2, 7, 2, 0};	int iWindowAttribsMask;	/* connect to display */	pDisplay = XOpenDisplay (NULL);	if (!pDisplay)	{		printf ("Could not open display\n");		return 1;	}	/* check for Xrender-extension */	if (!XRenderQueryExtension (pDisplay, &iEventBase, &iErrorBase))	{		XCloseDisplay (pDisplay);		printf ("Xrender-extension not found\n");		return 2;	}	/* see which version is available */	XRenderQueryVersion (pDisplay, &iMajorVersion, &iMinorVersion);	printf ("Found Xrender %d.%d\n", iMajorVersion, iMinorVersion);	/* make behave synchronous */	XSynchronize (pDisplay, True);	/* create and open window */	values.background_pixel = WhitePixel (pDisplay, 0);	values.event_mask = KeyPressMask;	iWindowAttribsMask = CWEventMask | CWBackPixel;	window = XCreateWindow (pDisplay,							RootWindow (pDisplay, 0),							50, 50, 400, 400, 0,							DefaultDepth (pDisplay, 0),							InputOutput,							DefaultVisual (pDisplay, 0),							iWindowAttribsMask,							&values);	XMapWindow (pDisplay, window);	/* now the guessing work starts,	** because Xrender is so "thoroughly" documented :-( */	pPictFormat = XRenderFindVisualFormat (pDisplay,										   DefaultVisual (pDisplay, 0));	picture = XRenderCreatePicture (pDisplay,									window,									pPictFormat,									0,									&pictAttribs);	/* results in a black rectangle ? */	XRenderFillRectangle (pDisplay,						  PictOpSrc,						  picture,						  &colorBlue,						  100, 200,						  120, 80);	while (bKeepGoing)	{		bGotEvent = XCheckWindowEvent (pDisplay,									   window,									   KeyPressMask,									   &event);		if (bGotEvent)		{			switch (event.type)			{				case KeyPress :					if (XLookupKeysym (&event.xkey, 0) == XK_Escape)						bKeepGoing = False;				break;			}		}		else			usleep (10000);	}	XUnmapWindow (pDisplay, window);	XDestroyWindow (pDisplay, window);	XCloseDisplay (pDisplay);	return 0;}