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Very small test program (#100 lines)

BlitAndBlend.cpp (text/x-csrc), 5.13 KB, created by axel mattauch on 2017-05-12 15:55:58 UTC

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Filename:

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Creator: axel mattauch

Created: 2017-05-12 15:55:58 UTC

Size: 5.13 KB

patch

obsolete

>// TEST14:   BlitAndBlend.cpp
>// 12/5/2017
>// SDL2: blitting, blending
>// ISO_C++ (C++11)
>
>#include    <cstdlib>      // EXIT_FAILURE, EXIT_SUCCESS
>#include    <SDL.h>
>
>int main( int argc, char* args[] )
>{
>SDL_Window     *  pwindow {NULL};
>SDL_Renderer   *  prenderer {NULL};
>SDL_Surface    *  psurface {NULL};
>SDL_Texture    *  ptexture {NULL};
>
>SDL_Rect       destRect {50, 50, 80, 80};
>
>SDL_PixelFormat   *  surfaceFormat;
>Uint32            pixelFormat;
>
>Uint32            pixelColor;
>
>   // 1/ code segment without execution control to remain simple (seems OK)
>   // ---------------------------------------------------------------------
>   SDL_Init( SDL_INIT_VIDEO );
>
>   pwindow  =  SDL_CreateWindow ("Blit and blend trials",
>               SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
>               600, 400 , SDL_WINDOW_SHOWN );
>   // For investigation purposes, we log window pixel format
>   pixelFormat = SDL_GetWindowPixelFormat(pwindow);
>   SDL_Log("Pixel format relevant to the window: %s", SDL_GetPixelFormatName(pixelFormat));
>   // On my computer "INFO: Pixel format relevant to the window: SDL_PIXELFORMAT_RGB888"
>
>   prenderer = SDL_CreateRenderer(pwindow, -1, 0);
>   // renderer initial color set to dark red; amask set to ff but obviously without effect (RGB)
>   SDL_SetRenderDrawColor ( prenderer,  0xD0, 0x00, 0x00, 0xFF) ;
>   SDL_RenderClear( prenderer );
>   SDL_RenderPresent(prenderer);
>   SDL_SetWindowTitle(pwindow,"Red background");
>   SDL_Delay (4000);
>   // On my computer, the window is colored in red
>
>   // 2/ code segment which seems working OK
>   // ---------------------------------------------------------------------
>   // Creating a 80*80 square with SDL_PIXELFORMAT_RGBA8888
>   psurface =  SDL_CreateRGBSurfaceWithFormat
>      (
>      0,                            // Uint32 flags   -unused
>      80,                           // int    width
>      80,                           // int    height
>      32,                           // int    depth
>      SDL_PIXELFORMAT_RGBA8888      //  SDL_PIXELFORMAT_RGBA32? SDL_PIXELFORMAT_RGBA8888 ?
>      );
>   if (psurface == NULL) {SDL_Log("SDL_CreateRGBSurfaceWithFormat problem: %s", SDL_GetError() );}
>   surfaceFormat     =  psurface->format;
>   pixelFormat       =  surfaceFormat->format;
>   SDL_Log("Effective Pixel format of the 'psurface' surface : %s", SDL_GetPixelFormatName(psurface->format->format));
>   // INFO: Effective Pixel format of the 'psurface' surface : SDL_PIXELFORMAT_RGBA8888
>
>   pixelColor = 0x00FF00FF; // Assumed to be green, with A = 100%. We understood RGBA as 0xRRGGBBAA ; may be wrong?
>   if (SDL_FillRect(psurface, NULL, pixelColor) != 0  ) {SDL_Log("SDL_FillRect problem: %s", SDL_GetError() );}
>
>   // First pixblt without blending, and creation of the associated texture
>   if (SDL_SetSurfaceBlendMode(psurface, SDL_BLENDMODE_NONE) != 0){SDL_Log("SDL_SetSurfaceBlendMode problem: %s", SDL_GetError() );}
>   ptexture = SDL_CreateTextureFromSurface(prenderer, psurface);
>   if (ptexture == NULL){SDL_Log("SDL_CreateTextureFromSurface problem: %s", SDL_GetError() );}
>   SDL_RenderCopy(prenderer, ptexture, NULL, &destRect);
>   SDL_RenderPresent(prenderer);
>   SDL_SetWindowTitle(pwindow,"Displaying the first square");
>   SDL_Delay (4000);
>   // On my computer, the square is effectively green
>
>   // 3/ code segment whithout execution errors, but with strange results
>   // ---------------------------------------------------------------------
>
>   // Updating the texture from the same surface
>   // It is expected that the update from an unchanged surface will be without effect: green square
>   if (SDL_UpdateTexture(ptexture, NULL, psurface->pixels, psurface->pitch) != 0)
>      { SDL_Log("SDL_UpdateTexture problem: %s", SDL_GetError() ); };
>
>     // May be I dont understood the usage or parametrisation of the SDL_UpdateTexture function?
>//   int SDL_UpdateTexture(SDL_Texture*    texture,   // the texture to update
>//                         const SDL_Rect* rect,      // an SDL_Rect structure representing the area to update,
>//                                                    // or NULL to update the entire texture
>//                         const void*     pixels,    // the raw pixel data
>//                         int             pitch)     // the number of bytes in a row of pixel data,
>//                                                    // including padding between lines
>
>   destRect.x += 100;
>   // Blitting the updated texture into the renderer
>   if (SDL_RenderCopy(prenderer, ptexture, NULL, &destRect) != 0)
>      { SDL_Log("SDL_RenderCopy: %s", SDL_GetError() ); };
>   SDL_RenderPresent(prenderer);
>   SDL_SetWindowTitle(pwindow,"Displaying the same square after texture refresh");
>   SDL_Delay (8000);
>   // at this stage the second square is of violet/magenta color and not green!
>
>
>   // 4/ code segment to release resources
>   // ---------------------------------------------------------------------
>
>   if (prenderer!=NULL) { SDL_DestroyRenderer(prenderer);prenderer=NULL; }
>   if (pwindow!=NULL)   { SDL_DestroyWindow (pwindow); pwindow = NULL; }
>   SDL_Quit();
>
>   exit(EXIT_SUCCESS);
>}

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We are currently migrating Bugzilla to GitHub issues.Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.

We are currently migrating Bugzilla to GitHub issues.
Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.
When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.