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How to use SDL_MapRGB with SDL 2.0


How to use SDL_MapRGB with SDL 2.0

By : Filippo
Date : November 25 2020, 07:27 PM
will help you I am trying to get a 24-bit color from rgb values. I want to use SDL_MapRGB, but I don't know what pixel format is. Since its SDL 2.0 I am using the SDL_Window and SDL_Renderer.
code :


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SDL_MapRGB is crashing with no error message

SDL_MapRGB is crashing with no error message


By : Changsheng Liu
Date : March 29 2020, 07:55 AM
this will help You seem to be calling SDL_FillRect() on an uninitialized pointer to SDL_Surface - which is either NULL or invalid and your code crashes right away (the lucky case) or happens to point to a valid memory location (and you end up corrupting your programs memory).
Depending on how you plan to use it later, either allocate some memory for your surface on the heap
code :
SDL_Surface *ecran = malloc(sizeof(SDL_Surface));
SDL_Surface ecran;
SDL_FillRect(&ecran, ...)
SDL_MapRGB, how to get screen->format using pointer to pointer

SDL_MapRGB, how to get screen->format using pointer to pointer


By : user2913022
Date : March 29 2020, 07:55 AM
I think the issue was by ths following , The unary * dereference operator has lower operator precedence than the structure pointer access operator ->. That means you're actually doing *(screen->format).
You need some parentheses to get the right precedence: (*screen)->format
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