[英]How do I take and save a BMP screenshot in SDL 2?
仅使用给定的 SDL_Window* 和 SDL_Renderer*,如何在 SDL 2.0 中创建和保存屏幕截图?
Below is a function for saving a screenshot in SDL 2 taken from a library I'm currently writing.下面是一个函数,用于在 SDL 2 中保存我正在编写的库中的屏幕截图。
bool saveScreenshotBMP(std::string filepath, SDL_Window* SDLWindow, SDL_Renderer* SDLRenderer) {
SDL_Surface* saveSurface = NULL;
SDL_Surface* infoSurface = NULL;
infoSurface = SDL_GetWindowSurface(SDLWindow);
if (infoSurface == NULL) {
std::cerr << "Failed to create info surface from window in saveScreenshotBMP(string), SDL_GetError() - " << SDL_GetError() << "\n";
} else {
unsigned char * pixels = new (std::nothrow) unsigned char[infoSurface->w * infoSurface->h * infoSurface->format->BytesPerPixel];
if (pixels == 0) {
std::cerr << "Unable to allocate memory for screenshot pixel data buffer!\n";
return false;
} else {
if (SDL_RenderReadPixels(SDLRenderer, &infoSurface->clip_rect, infoSurface->format->format, pixels, infoSurface->w * infoSurface->format->BytesPerPixel) != 0) {
std::cerr << "Failed to read pixel data from SDL_Renderer object. SDL_GetError() - " << SDL_GetError() << "\n";
delete[] pixels;
return false;
} else {
saveSurface = SDL_CreateRGBSurfaceFrom(pixels, infoSurface->w, infoSurface->h, infoSurface->format->BitsPerPixel, infoSurface->w * infoSurface->format->BytesPerPixel, infoSurface->format->Rmask, infoSurface->format->Gmask, infoSurface->format->Bmask, infoSurface->format->Amask);
if (saveSurface == NULL) {
std::cerr << "Couldn't create SDL_Surface from renderer pixel data. SDL_GetError() - " << SDL_GetError() << "\n";
delete[] pixels;
return false;
}
SDL_SaveBMP(saveSurface, filepath.c_str());
SDL_FreeSurface(saveSurface);
saveSurface = NULL;
}
delete[] pixels;
}
SDL_FreeSurface(infoSurface);
infoSurface = NULL;
}
return true;
}
Cheers!干杯! -Neil -尼尔
If you are using OpenGL with SDL2 you can call glReadPixels
directly instead of using the info surface and renderer.如果您将 OpenGL 与 SDL2 一起使用,您可以直接调用glReadPixels
而不是使用信息表面和渲染器。 Here is an example (without error checking).这是一个示例(没有错误检查)。
void Screenshot(int x, int y, int w, int h, const char * filename)
{
unsigned char * pixels = new unsigned char[w*h*4]; // 4 bytes for RGBA
glReadPixels(x,y,w, h, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
SDL_Surface * surf = SDL_CreateRGBSurfaceFrom(pixels, w, h, 8*4, w*4, 0,0,0,0);
SDL_SaveBMP(surf, filename);
SDL_FreeSurface(surf);
delete [] pixels;
}
Here's the SDL wiki page with an example of setting up the window and an OpenGL context.这是SDL wiki 页面,其中包含设置窗口和 OpenGL 上下文的示例。
Edit: If you are tempted to copy/paste this snippet, remember to add some error checking编辑:如果您想复制/粘贴此代码段,请记住添加一些错误检查
void Screenshot(int x, int y, int w, int h, const char * filename)
{
Uint32 rmask, gmask, bmask, amask;
rmask = 0x000000ff;
gmask = 0x0000ff00;
bmask = 0x00ff0000;
amask = 0xff000000;
unsigned char * pixels = new unsigned char[w*h*4]; // 4 bytes for RGBA
glReadPixels(x, y, w, h, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
SDL_Surface * surf = SDL_CreateRGBSurfaceFrom(pixels, w, h, 8*4, w*4, rmask, gmask, bmask, amask);
SDL_SaveBMP(surf, filename);
SDL_FreeSurface(surf);
delete [] pixels;
}
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