the last parameter of XChangeProperty is the number of elements.. and when the element format is 32.. the element is "long" so we have 5 long elements here.

Yes this seems confusing as on mac+linux Long is either 32 or 64bits depending on the architecture, but this is how the X11 protocol is defined. Thus 5 is the correct value for the nelts here. Not 5 or 10 depending on the architecture. More info on the confusion https://bugs.freedesktop.org/show_bug.cgi?id=16802
2026-04-23 17:30:39 +02:00 · 2015-02-10 16:28:56 -05:00
commit b88ca1b4a6
1638 changed files with 474135 additions and 0 deletions
--- a/test/testdrawchessboard.c
+++ b/test/testdrawchessboard.c
@@ -0,0 +1,129 @@
+/*
+   Copyright (C) 1997-2014 Sam Lantinga <slouken@libsdl.org>
+
+   This software is provided 'as-is', without any express or implied
+   warranty.  In no event will the authors be held liable for any damages
+   arising from the use of this software.
+
+   Permission is granted to anyone to use this software for any purpose,
+   including commercial applications, and to alter it and redistribute it
+   freely.
+
+   This file is created by : Nitin Jain (nitin.j4@samsung.com)
+*/
+
+/* Sample program:  Draw a Chess Board  by using SDL_CreateSoftwareRenderer API */
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#ifdef __EMSCRIPTEN__
+#include <emscripten/emscripten.h>
+#endif
+
+#include "SDL.h"
+
+SDL_Window *window;
+SDL_Renderer *renderer;
+int done;
+
+void
+DrawChessBoard(SDL_Renderer * renderer)
+{
+	int row = 0,column = 0,x = 0;
+	SDL_Rect rect, darea;
+
+	/* Get the Size of drawing surface */
+	SDL_RenderGetViewport(renderer, &darea);
+
+	for( ; row < 8; row++)
+	{
+		column = row%2;
+		x = x + column;
+		for( ; column < 4+(row%2); column++)
+		{
+			SDL_SetRenderDrawColor(renderer, 0, 0, 0, 0xFF);
+
+			rect.w = darea.w/8;
+			rect.h = darea.h/8;
+			rect.x = x * rect.w;
+			rect.y = row * rect.h;
+			x = x + 2;
+			SDL_RenderFillRect(renderer, &rect);
+		}
+		x=0;
+	}
+}
+
+void
+loop()
+{
+    SDL_Event e;
+	if (SDL_PollEvent(&e)) {
+		if (e.type == SDL_QUIT) {
+			done = 1;
+			return;
+		}
+
+		if(e.key.keysym.sym == SDLK_ESCAPE) {
+			done = 1;
+			return;
+		}
+	}
+	
+	DrawChessBoard(renderer);
+	
+	/* Got everything on rendering surface,
+	   now Update the drawing image on window screen */
+	SDL_UpdateWindowSurface(window);
+}
+
+int
+main(int argc, char *argv[])
+{
+	SDL_Surface *surface;
+
+    /* Enable standard application logging */
+    SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);
+
+	/* Initialize SDL */
+	if(SDL_Init(SDL_INIT_VIDEO) != 0)
+	{
+		SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "SDL_Init fail : %s\n", SDL_GetError());
+		return 1;
+	}
+
+
+	/* Create window and renderer for given surface */
+	window = SDL_CreateWindow("Chess Board", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 640, 480, SDL_WINDOW_SHOWN);
+	if(!window)
+	{
+		SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Window creation fail : %s\n",SDL_GetError());
+		return 1;
+	}	
+	surface = SDL_GetWindowSurface(window);
+	renderer = SDL_CreateSoftwareRenderer(surface);
+	if(!renderer)
+	{
+		SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Render creation for surface fail : %s\n",SDL_GetError());
+		return 1;
+	}
+
+	/* Clear the rendering surface with the specified color */
+	SDL_SetRenderDrawColor(renderer, 0xFF, 0xFF, 0xFF, 0xFF);
+	SDL_RenderClear(renderer);
+
+
+	/* Draw the Image on rendering surface */
+	done = 0;
+#ifdef __EMSCRIPTEN__
+    emscripten_set_main_loop(loop, 0, 1);
+#else
+    while (!done) {
+        loop();
+	}
+#endif
+
+	return 0;
+}
+