1 /*
2   Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
3 
4   This software is provided 'as-is', without any express or implied
5   warranty.  In no event will the authors be held liable for any damages
6   arising from the use of this software.
7 
8   Permission is granted to anyone to use this software for any purpose,
9   including commercial applications, and to alter it and redistribute it
10   freely.
11 */
12 
13 /* Simple program: picks the offscreen backend and renders each frame to a bmp */
14 
15 #include <stdlib.h>
16 #include <stdio.h>
17 #include <time.h>
18 
19 #ifdef __EMSCRIPTEN__
20 #include <emscripten/emscripten.h>
21 #endif
22 
23 #include "SDL.h"
24 #include "SDL_stdinc.h"
25 #include "SDL_opengl.h"
26 
27 static SDL_Renderer *renderer = NULL;
28 static SDL_Window *window = NULL;
29 static int done = SDL_FALSE;
30 static int frame_number = 0;
31 static int width = 640;
32 static int height = 480;
33 static int max_frames = 200;
34 
35 void
draw()36 draw()
37 {
38     SDL_Rect Rect;
39 
40     SDL_SetRenderDrawColor(renderer, 0x10, 0x9A, 0xCE, 0xFF);
41     SDL_RenderClear(renderer);
42 
43     /* Grow based on the frame just to show a difference per frame of the region */
44     Rect.x = 0;
45     Rect.y = 0;
46     Rect.w = (frame_number * 2) % width;
47     Rect.h = (frame_number * 2) % height;
48     SDL_SetRenderDrawColor(renderer, 0xFF, 0x10, 0x21, 0xFF);
49     SDL_RenderFillRect(renderer, &Rect);
50 
51     SDL_RenderPresent(renderer);
52 }
53 
54 void
save_surface_to_bmp()55 save_surface_to_bmp()
56 {
57     SDL_Surface* surface;
58     Uint32 r_mask, g_mask, b_mask, a_mask;
59     Uint32 pixel_format;
60     char file[128];
61     int bbp;
62 
63     pixel_format = SDL_GetWindowPixelFormat(window);
64     SDL_PixelFormatEnumToMasks(pixel_format, &bbp, &r_mask, &g_mask, &b_mask, &a_mask);
65 
66     surface = SDL_CreateRGBSurface(0, width, height, bbp, r_mask, g_mask, b_mask, a_mask);
67     SDL_RenderReadPixels(renderer, NULL, pixel_format, (void*)surface->pixels, surface->pitch);
68 
69     SDL_snprintf(file, sizeof(file), "SDL_window%d-%8.8d.bmp",
70         SDL_GetWindowID(window), ++frame_number);
71 
72     SDL_SaveBMP(surface, file);
73     SDL_FreeSurface(surface);
74 }
75 
76 void
loop()77 loop()
78 {
79     SDL_Event event;
80 
81     /* Check for events */
82     while (SDL_PollEvent(&event)) {
83         switch (event.type) {
84             case SDL_QUIT:
85             done = SDL_TRUE;
86             break;
87         }
88     }
89 
90     draw();
91     save_surface_to_bmp();
92 
93 #ifdef __EMSCRIPTEN__
94     if (done) {
95         emscripten_cancel_main_loop();
96     }
97 #endif
98 }
99 
100 int
main(int argc,char * argv[])101 main(int argc, char *argv[])
102 {
103     Uint32 then, now, frames;
104 
105     /* Enable standard application logging */
106     SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);
107 
108     /* Force the offscreen renderer, if it cannot be created then fail out */
109     if (SDL_VideoInit("offscreen") < 0) {
110         SDL_Log("Couldn't initialize the offscreen video driver: %s\n",
111             SDL_GetError());
112         return SDL_FALSE;
113     }
114 
115 	/* If OPENGL fails to init it will fallback to using a framebuffer for rendering */
116     window = SDL_CreateWindow("Offscreen Test",
117                  SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
118                  width, height, 0);
119 
120     if (!window) {
121         SDL_Log("Couldn't create window: %s\n",
122             SDL_GetError());
123         return SDL_FALSE;
124     }
125 
126     renderer = SDL_CreateRenderer(window, -1, 0);
127 
128     if (!renderer) {
129         SDL_Log("Couldn't create renderer: %s\n",
130             SDL_GetError());
131         return SDL_FALSE;
132     }
133 
134     SDL_RenderClear(renderer);
135 
136     srand((unsigned int)time(NULL));
137 
138     /* Main render loop */
139     frames = 0;
140     then = SDL_GetTicks();
141     done = 0;
142 
143     SDL_Log("Rendering %i frames offscreen\n", max_frames);
144 
145 #ifdef __EMSCRIPTEN__
146     emscripten_set_main_loop(loop, 0, 1);
147 #else
148     while (!done && frames < max_frames) {
149         ++frames;
150         loop();
151 
152         /* Print out some timing information, along with remaining frames */
153         if (frames % (max_frames / 10) == 0) {
154             now = SDL_GetTicks();
155             if (now > then) {
156                 double fps = ((double) frames * 1000) / (now - then);
157                 SDL_Log("Frames remaining: %i rendering at %2.2f frames per second\n", max_frames - frames, fps);
158             }
159         }
160     }
161 #endif
162 
163     SDL_DestroyRenderer(renderer);
164     SDL_DestroyWindow(window);
165     SDL_Quit();
166 
167     return 0;
168 }
169 
170 /* vi: set ts=4 sw=4 expandtab: */
171