mirror of
https://github.com/google/sandboxed-api.git
synced 2024-03-22 13:11:30 +08:00
134 lines
3.9 KiB
C
134 lines
3.9 KiB
C
/*
|
|
LodePNG Examples
|
|
|
|
Copyright (c) 2005-2012 Lode Vandevenne
|
|
|
|
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, subject to the following restrictions:
|
|
|
|
1. The origin of this software must not be misrepresented; you must not
|
|
claim that you wrote the original software. If you use this software
|
|
in a product, an acknowledgment in the product documentation would be
|
|
appreciated but is not required.
|
|
|
|
2. Altered source versions must be plainly marked as such, and must not be
|
|
misrepresented as being the original software.
|
|
|
|
3. This notice may not be removed or altered from any source
|
|
distribution.
|
|
*/
|
|
|
|
/*
|
|
Compile command for Linux:
|
|
gcc lodepng.c example_sdl.c -ansi -pedantic -Wall -Wextra -lSDL -O3 -o showpng
|
|
|
|
*/
|
|
|
|
/*
|
|
LodePNG SDL example
|
|
This example displays a PNG with a checkerboard pattern to show tranparency.
|
|
It requires the SDL library to compile and run.
|
|
If multiple filenames are given to the command line, it shows all of them.
|
|
Press any key to see next image, or esc to quit.
|
|
*/
|
|
|
|
#include "lodepng.h"
|
|
|
|
#include <SDL/SDL.h>
|
|
|
|
/*shows image with SDL. Returns 1 if user wants to fully quit, 0 if user wants to see next image.*/
|
|
int show(const char* filename) {
|
|
unsigned error;
|
|
unsigned char* image;
|
|
unsigned w, h, x, y;
|
|
SDL_Surface* scr;
|
|
SDL_Event event;
|
|
int done;
|
|
size_t jump = 1;
|
|
|
|
printf("showing %s\n", filename);
|
|
|
|
/*load the PNG in one function call*/
|
|
error = lodepng_decode32_file(&image, &w, &h, filename);
|
|
|
|
/*stop if there is an error*/
|
|
if(error) {
|
|
printf("decoder error %u: %s\n", error, lodepng_error_text(error));
|
|
return 0;
|
|
}
|
|
|
|
/*avoid too large window size by downscaling large image*/
|
|
|
|
if(w / 1024 >= jump) jump = w / 1024 + 1;
|
|
if(h / 1024 >= jump) jump = h / 1024 + 1;
|
|
|
|
/*init SDL*/
|
|
if(SDL_Init(SDL_INIT_VIDEO) < 0) {
|
|
printf("Error, SDL video init failed\n");
|
|
return 0;
|
|
}
|
|
scr = SDL_SetVideoMode(w / jump, h / jump, 32, SDL_HWSURFACE);
|
|
if(!scr) {
|
|
printf("Error, no SDL screen\n");
|
|
return 0;
|
|
}
|
|
SDL_WM_SetCaption(filename, NULL); /*set window caption*/
|
|
|
|
/*plot the pixels of the PNG file*/
|
|
for(y = 0; y + jump - 1 < h; y += jump)
|
|
for(x = 0; x + jump - 1 < w; x += jump) {
|
|
int checkerColor;
|
|
Uint32* bufp;
|
|
Uint32 r, g, b, a;
|
|
|
|
/*get RGBA components*/
|
|
r = image[4 * y * w + 4 * x + 0]; /*red*/
|
|
g = image[4 * y * w + 4 * x + 1]; /*green*/
|
|
b = image[4 * y * w + 4 * x + 2]; /*blue*/
|
|
a = image[4 * y * w + 4 * x + 3]; /*alpha*/
|
|
|
|
/*make translucency visible by placing checkerboard pattern behind image*/
|
|
checkerColor = 191 + 64 * (((x / 16) % 2) == ((y / 16) % 2));
|
|
r = (a * r + (255 - a) * checkerColor) / 255;
|
|
g = (a * g + (255 - a) * checkerColor) / 255;
|
|
b = (a * b + (255 - a) * checkerColor) / 255;
|
|
|
|
/*give the color value to the pixel of the screenbuffer*/
|
|
bufp = (Uint32 *)scr->pixels + (y * scr->pitch / 4) / jump + (x / jump);
|
|
*bufp = 65536 * r + 256 * g + b;
|
|
}
|
|
|
|
/*pause until you press escape and meanwhile redraw screen*/
|
|
done = 0;
|
|
while(done == 0) {
|
|
while(SDL_PollEvent(&event)) {
|
|
if(event.type == SDL_QUIT) done = 2;
|
|
else if(SDL_GetKeyState(NULL)[SDLK_ESCAPE]) done = 2;
|
|
else if(event.type == SDL_KEYDOWN) done = 1; /*press any other key for next image*/
|
|
}
|
|
SDL_UpdateRect(scr, 0, 0, 0, 0); /*redraw screen*/
|
|
SDL_Delay(5); /*pause 5 ms so it consumes less processing power*/
|
|
}
|
|
|
|
/*cleanup*/
|
|
free(image);
|
|
SDL_Quit();
|
|
return done == 2 ? 1 : 0;
|
|
}
|
|
|
|
int main(int argc, char* argv[]) {
|
|
int i;
|
|
|
|
if(argc <= 1) printf("Please enter PNG file name(s) to display\n");;
|
|
|
|
for(i = 1; i < argc; i++) {
|
|
if(show(argv[i])) return 0;
|
|
}
|
|
return 0;
|
|
}
|