DPI with SDL_Renderer

1#include <SDL.h>
2#include <iostream>
3
DPI Scale Helper|Show
4float GetDPIScale(SDL_Window* Window) {/*...*/}
11
12int main() {
13  SDL_SetHint(
14    SDL_HINT_WINDOWS_DPI_SCALING, "1");
15  SDL_Init(SDL_INIT_VIDEO);
16
17  SDL_Window* Window{SDL_CreateWindow(
18    "Renderer DPI Demo",
19    SDL_WINDOWPOS_UNDEFINED,
20    SDL_WINDOWPOS_UNDEFINED,
21    800, 600,
22    SDL_WINDOW_ALLOW_HIGHDPI
23  )};
24
25  SDL_Renderer* Renderer{SDL_CreateRenderer(
26    Window,
27    -1,
28    SDL_RENDERER_ACCELERATED
29  )};
30
31  // Set logical size to match our design resolution
32  float Scale{GetDPIScale(Window)};
33  int DesignWidth{800};
34  int DesignHeight{600};
35
36  SDL_RenderSetLogicalSize(
37    Renderer,
38    DesignWidth,
39    DesignHeight
40  );
41
42  // Main loop
43  SDL_Event E;
44  bool Running{true};
45  while (Running) {
46    while (SDL_PollEvent(&E)) {
47      if (E.type == SDL_QUIT) Running = false;
48    }
49
50    // Clear and render
51    SDL_SetRenderDrawColor(
52      Renderer, 50, 50, 50, 255);
53    SDL_RenderClear(Renderer);
54
55    // Draw a rectangle that will maintain its physical size
56    SDL_SetRenderDrawColor(
57      Renderer, 150, 50, 50, 255);
58    SDL_Rect Rect{100, 100, 200, 100};
59    SDL_RenderFillRect(Renderer, &Rect);
60
61    SDL_RenderPresent(Renderer);
62  }
63
64  SDL_DestroyRenderer(Renderer);
65  SDL_DestroyWindow(Window);
66  SDL_Quit();
67  return 0;
68}

1SDL_Texture* CreateTexture(
2  SDL_Renderer* Renderer,
3  int Width,
4  int Height
5) {
6  return SDL_CreateTexture(
7    Renderer,
8    SDL_PIXELFORMAT_RGBA8888,
9    SDL_TEXTUREACCESS_TARGET,
10    Width, Height
11  );
12}
13
14void RenderWithTexture(
15  SDL_Renderer* Renderer) {
16  // Create a texture at our design resolution
17  SDL_Texture* Target{CreateTexture(
18    Renderer, 800, 600)};
19
20  // Set it as the render target
21  SDL_SetRenderTarget(Renderer, Target);
22
23  // Render to texture...
24  SDL_SetRenderDrawColor(Renderer,
25    150, 50, 50, 255);
26  SDL_Rect Rect{100, 100, 200, 100};
27  SDL_RenderFillRect(Renderer, &Rect);
28
29  // Reset target and render the texture
30  SDL_SetRenderTarget(Renderer, nullptr);
31  SDL_RenderCopy(Renderer, Target, nullptr, nullptr);
32}