CODEWITHSUNDEEP
c++gdbsdlsdl-2
RandomUser
RandomUser

Reputation: 4220

SDL2 - Problems creating texture from surface (Screenshot)

The below code runs fine on my macbook, but segfaults when I run on Linux:

gdb says it's happening here (line 81):

  mBackgroundTexture = SDL_CreateTextureFromSurface(mSDLRenderer, saveSurface);

GDB output:

Thread 1 "Testapp.bin" received signal SIGSEGV, Segmentation fault.
_int_malloc (av=av@entry=0x7ffff6b9fb20 <main_arena>, bytes=bytes@entry=147479) at malloc.c:3728
3728    malloc.c: No such file or directory.
(gdb) bt
#0  _int_malloc (av=av@entry=0x7ffff6b9fb20 <main_arena>, bytes=bytes@entry=147479) at malloc.c:3728
#1  0x00007ffff685f5a4 in __GI___libc_malloc (bytes=147479) at malloc.c:2914
#2  0x00007fffedb126a9 in ?? () from /usr/lib/nvidia-367/libGLX_nvidia.so.0
#3  0x00007fffecb1eaf7 in ?? () from /usr/lib/nvidia-367/libnvidia-glcore.so.367.57
#4  0x00007fffecb0c30d in ?? () from /usr/lib/nvidia-367/libnvidia-glcore.so.367.57
#5  0x00007fffecbe40c4 in ?? () from /usr/lib/nvidia-367/libnvidia-glcore.so.367.57
#6  0x00007fffecbe5a0b in ?? () from /usr/lib/nvidia-367/libnvidia-glcore.so.367.57
#7  0x00007fffec871799 in ?? () from /usr/lib/nvidia-367/libnvidia-glcore.so.367.57
#8  0x00007fffec87b64c in ?? () from /usr/lib/nvidia-367/libnvidia-glcore.so.367.57
#9  0x00007fffec87f6b1 in ?? () from /usr/lib/nvidia-367/libnvidia-glcore.so.367.57
#10 0x00007fffec899127 in ?? () from /usr/lib/nvidia-367/libnvidia-glcore.so.367.57
#11 0x00007ffff7b22850 in ?? () from /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0
#12 0x00007ffff7b1bbeb in ?? () from /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0
#13 0x00007ffff7b1bf0b in ?? () from /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0
#14 0x000000000043110a in MinimapRenderer::createBGTexture (this=0xc4f300, viewport=...)
    at renderers/MinimapRenderer.cpp:81

Code:

void MinimapRenderer::createBGTexture(const Viewport &viewport)
{
    SDL_Surface *sshot = SDL_CreateRGBSurface(0, viewport.getRect().w, viewport.getRect().h, 32, 0x00ff0000, 0x0000ff00, 0x000000ff, 0xff000000);

    if (sshot != NULL)
    {
        if (SDL_RenderReadPixels(mSDLRenderer, NULL, SDL_PIXELFORMAT_ARGB8888, sshot->pixels, sshot->pitch) == 0)
        {
            SDL_Surface *saveSurface = SDL_CreateRGBSurfaceFrom(sshot->pixels, viewport.getRect().w, viewport.getRect().h, 32, sshot->pitch, 0x00ff0000, 0x0000ff00, 0x000000ff, 0xff000000);
            if (saveSurface != NULL)
            {
                mBackgroundTexture = SDL_CreateTextureFromSurface(mSDLRenderer, saveSurface);
                if (mBackgroundTexture != NULL)
                {
                    SDL_SaveBMP(saveSurface, "winning.bmp");
                }
                else
                {
                    SDL_Log("MinimapRenderer::createBGTexture --  SDL_CreateTextureFromSurface error: %s  \n", SDL_GetError());
                }

                SDL_FreeSurface(saveSurface);
            }
            else
            {
                SDL_Log("MinimapRenderer::createBGTexture --  SDL_CreateRGBSurfaceFrom error: %s \n", SDL_GetError());
            }
        }
        else
        {
            SDL_Log("MinimapRenderer::createBGTexture -- SDL_RenderReadPixels error: %s \n", SDL_GetError());
        }

        SDL_FreeSurface(sshot);
    }
    else
    {
        SDL_Log("MinimapRenderer::createBGTexture --  SDL_CreateRGBSurface error: %s \n", SDL_GetError());
    }
}

Appreciate any ideas to debug further, let me know if there is additional info I could provide that would help

Upvotes: 0

Views: 688

Answers (1)

RandomUser
RandomUser

Reputation: 4220

I was able to trace the problem SDL_RenderReadPixels, instead of passing a NULL rect passing a rect seems to have solved the problem. Simplified version of code that works without error checking, hopefully it helps someone:

SDL_Rect rendRect = { 0, 0, viewport.getRect().w, viewport.getRect().h };
    SDL_Surface *sshot = SDL_CreateRGBSurface(0, viewport.getRect().w, viewport.getRect().h, 32, 0x00ff0000, 0x0000ff00, 0x000000ff, 0xff000000);
    SDL_RenderReadPixels(mSDLRenderer, &rendRect, SDL_PIXELFORMAT_ARGB8888, sshot->pixels, sshot->pitch);
    mBackgroundTexture = SDL_CreateTextureFromSurface(mSDLRenderer, sshot);
    SDL_SaveBMP(sshot, "screenshot.bmp");
    SDL_FreeSurface(sshot);

Upvotes: 2

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