Paint a image in Cairo surface X11

Alex Vazquez <[email protected]> Fri, 5 Feb 2016 15:13:02 +0100

Newsgroups	gmane.comp.lib.cairo
Message-ID	<CAOTEMURG3o+TaJBewnP-T0q8GMwASNH8_=tQbOL460qy0z2N3A@mail.gmail.com>

I have a problem when I paint a image using Cairo and X11.
The test is simple I try paint a image in a  X11 Windows using Cairo.
If the size of surface  is less that size of image, X11 don't show the
image but If the  size of surface  is bigger that the size of image  X11
show fine the image.

Why is happen?
How can i fix this problem?
I add a test where you can test this problem.

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Makefile (application/octet-stream, 397 B) - not displayed

cairo_xlib_simple.c (text/x-csrc, 2.3 KB)

#include <X11/Xlib.h>
#include <X11/Xatom.h>
#include <X11/Xutil.h>
#include <cairo.h>
#include <cairo-xlib.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

void cairo_close_x11_surface();

static Display *dsp;
cairo_surface_t *sfc;
int cairo_check_event(cairo_surface_t *sfc, int block)
{

   XEvent e;

   for (;;)
   {
      ///if (block || XPending(cairo_xlib_surface_get_display(sfc)))
         XNextEvent(cairo_xlib_surface_get_display(sfc), &e);
      //else 
      //   return 0;

      switch (e.type)
      {
      	case ButtonPress:
      		cairo_close_x11_surface();
      	break;
         default:

         break;
      }
   }
}

/*! Open an X11 window and create a cairo surface base on that window.
 * @param x Width of window.
 * @param y Height of window.
 * @return Returns a pointer to a valid Xlib cairo surface. The function does
 * not return on error (exit(3)).
 */
cairo_surface_t *cairo_create_x11_surface0(int x, int y)
{
   //Display *dsp;
   Drawable da;
   int screen;

   if ((dsp = XOpenDisplay(NULL)) == NULL)
      exit(1);
   screen = DefaultScreen(dsp);
   da = XCreateSimpleWindow(dsp, DefaultRootWindow(dsp), 0, 0, x, y, 0, 0, 0);
   XSelectInput(dsp, da, ButtonPressMask | ButtonReleaseMask);
   XMapWindow(dsp, da);

   XFlush(dsp);
   XSync(dsp, screen);
    
   sfc = cairo_xlib_surface_create(dsp, da, DefaultVisual(dsp, screen), x, y);
   cairo_xlib_surface_set_size(sfc, x, y);

   return sfc;
}


/*! Destroy cairo Xlib surface and close X connection.
 */
void cairo_close_x11_surface()
{
   Display *dsp = cairo_xlib_surface_get_display(sfc);

   cairo_surface_destroy(sfc);
   XCloseDisplay(dsp);
}


int main(int argc, char **argv)
{

   cairo_surface_t *sfc;
   cairo_t *ctx;
   cairo_surface_t *image;
   int w, h;
   int iwidth,iheight;

   if (argc < 3)
	{
		printf("./cairo_xlib_simple [Width] [Height]\n");
		return 1;
	}
	iwidth = atoi(argv[1]);
	iheight = atoi(argv[2]);

   sfc = cairo_create_x11_surface0(iwidth, iheight);
   ctx = cairo_create(sfc);

  
   image = cairo_image_surface_create_from_png ("photo.png");
   cairo_set_source_surface (ctx, image, 0, 0);
	cairo_paint (ctx);
	w = cairo_image_surface_get_width (image);
	h = cairo_image_surface_get_height (image);
	printf("Size: %dx%d\n",w,h );
   XFlush(dsp);

   cairo_destroy(ctx);
   cairo_check_event(sfc, 1);
   cairo_close_x11_surface(sfc);

   return 0;
}