From f7e3d992c9b2afcf2896adc9dfb91ef2e3c2914d Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <icculus@icculus.org>
Date: Fri, 5 Oct 2012 22:41:02 -0400
Subject: [PATCH] Try to use _NET_WM_ICON if possible for X11's
 SDL_WM_SetIcon() implementation.

This lets us have larger icons with more colors.
---
 src/video/x11/SDL_x11wm.c | 75 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/src/video/x11/SDL_x11wm.c b/src/video/x11/SDL_x11wm.c
index 14c816b94..cb77a78f7 100644
--- a/src/video/x11/SDL_x11wm.c
+++ b/src/video/x11/SDL_x11wm.c
@@ -43,6 +43,7 @@ static Uint8 reverse_byte(Uint8 x)
 
 void X11_SetIcon(_THIS, SDL_Surface *icon, Uint8 *mask)
 {
+	Atom _NET_WM_ICON = XInternAtom(SDL_Display, "_NET_WM_ICON", False);
 	SDL_Surface *sicon;
 	XWMHints *wmhints;
 	XImage *icon_image;
@@ -60,6 +61,80 @@ void X11_SetIcon(_THIS, SDL_Surface *icon, Uint8 *mask)
 
 	SDL_Lock_EventThread();
 
+	if (_NET_WM_ICON) {   /* better interface for modern systems. */
+		SDL_PixelFormat format;
+		SDL_Surface *surface;
+		int propsize;
+		long *propdata;
+
+		/* Convert the icon to ARGB for modern window managers */
+		SDL_memset(&format, 0, sizeof (format));
+		format.BitsPerPixel = 32;
+		format.BytesPerPixel = 4;
+		#if SDL_BYTEORDER == SDL_BIG_ENDIAN
+		format.Rshift = 8;
+		format.Gshift = 16;
+		format.Bshift = 24;
+		format.Ashift = 0;
+		#else
+		format.Rshift = 16;
+		format.Gshift = 8;
+		format.Bshift = 0;
+		format.Ashift = 24;
+		#endif
+		format.Rmask = 0xFF << format.Rshift;
+		format.Gmask = 0xFF << format.Gshift;
+		format.Bmask = 0xFF << format.Bshift;
+		format.Amask = 0xFF << format.Ashift;
+		format.alpha = SDL_ALPHA_OPAQUE;
+
+		surface = SDL_ConvertSurface(icon, &format, 0);
+		if (!surface) {
+			return;
+		}
+
+		/* Set the _NET_WM_ICON property */
+		propsize = 2 + (icon->w * icon->h);
+		propdata = SDL_malloc(propsize * sizeof(long));
+		if (propdata) {
+			const Uint32 alpha = format.Amask;
+			int x, y;
+			Uint32 *src;
+			long *dst;
+
+			propdata[0] = icon->w;
+			propdata[1] = icon->h;
+			dst = &propdata[2];
+
+			size_t maskidx = 0;
+			for (y = 0; y < icon->h; ++y) {
+				src = (Uint32*)((Uint8*)surface->pixels + y * surface->pitch);
+				for (x = 0; x < icon->w; ++x) {
+					const Uint32 pixel = *(src++);
+					if (mask[maskidx / 8] & (1<<(7-(maskidx % 8)))) {
+						*dst++ = pixel | alpha;
+					} else {
+						*dst++ = pixel & ~alpha;
+					}
+					maskidx++;
+				}
+			}
+
+			XChangeProperty(SDL_Display, WMwindow, _NET_WM_ICON, XA_CARDINAL,
+			                32, PropModeReplace, (unsigned char *) propdata,
+			                propsize);
+		}
+
+		SDL_FreeSurface(surface);
+		SDL_free(propdata);
+
+		SDL_Unlock_EventThread();
+
+		return;
+	}
+
+	/* Do it the old way... */
+
 	/* The icon must use the default visual, depth and colormap of the
 	   screen, so it might need a conversion */
 	dvis = DefaultVisual(SDL_Display, SDL_Screen);