Change background of SDL2 window? - c++

Question

I can create a SDL2 window but I don't know how to change background color of this window.
My code:
#include "SDL.h"
SDL_Window *window;
void main()
{
window = SDL_CreateWindow("TEST", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_SHOWN);
SDL_Delay(3000);
}
How can I change background color of this window to black?

Answer 1

You should set drawing colour with SDL_SetRenderDrawColor and then use SDL_RenderClear:
(code comes directly from SDL wiki)
int main(int argc, char* argv[])
{
SDL_Window* window;
SDL_Renderer* renderer;
// Initialize SDL.
if (SDL_Init(SDL_INIT_VIDEO) < 0)
return 1;
// Create the window where we will draw.
window = SDL_CreateWindow("SDL_RenderClear",
SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
512, 512,
0);
// We must call SDL_CreateRenderer in order for draw calls to affect this window.
renderer = SDL_CreateRenderer(window, -1, 0);
// Select the color for drawing. It is set to red here.
SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);
// Clear the entire screen to our selected color.
SDL_RenderClear(renderer);
// Up until now everything was drawn behind the scenes.
// This will show the new, red contents of the window.
SDL_RenderPresent(renderer);
// Give us time to see the window.
SDL_Delay(5000);
// Always be sure to clean up
SDL_Quit();
return 0;
}

Answer 2

If you do not use SDL2 renderer you can do this:
Just call:
SDL_GL_SwapWindow(window);
After :
SDL_GL_MakeCurrent(window, context);
That's all! Now you have a black screen.

Answer 3

#include <SDL2/SDL.h>
#include <iostream>
using namespace std;
int main(){
int width=512, height=512;
SDL_Window *window=SDL_CreateWindow("Window", SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED, width, height, SDL_WINDOW_RESIZABLE);
if(window==NULL)
cout << "There was an error while initializing the window" << endl << SDL_GetError << endl;
SDL_Event event;
bool running=true;
while(running){
while(SDL_PollEvent(&event)){
if(event.type==SDL_QUIT){
running=false;
break;
}
}
SDL_GetWindowSize(window, &width, &height);
SDL_Surface *surface=SDL_GetWindowSurface(window);
Uint32 skyblue=SDL_MapRGB(surface->format, 65,193,193);
SDL_FillRect(surface, NULL, skyblue);
SDL_UpdateWindowSurface(window);
}
SDL_DestroyWindow(window);
SDL_Quit();
}

Answer 4

Note, none of these solutions work properly with OpenGL. The question was how to init the window with predefined color, not how to paint the first frame. There's still a blink of white color before the first frame is painted.

Answer 5

Try this one :
SDL_Window *wind;
SDL_Surface *windSurface = NULL
void main()
{
wind = SDL_CreateWindow("TEST", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_SHOWN);
windSurface = SDL_GetWindowSurface(wind);
SDL_FillRect(windSurface, NULL, SDL_MapRGB(windSurface->format, 240, 200, 112));
SDL_UpdateWindowSurface(wind);
SDL_Delay(3000);
}