Scaling Text in SDL

1#include <SDL.h>
2#include <SDL_ttf.h>
3#include <iostream>
4
5float GetDPIScale(SDL_Window* Window) {
6  int w1, w2;
7  SDL_GetWindowSize(Window, &w1, nullptr);
8  SDL_GetWindowSizeInPixels(
9    Window, &w2, nullptr);
10  return float(w2) / w1;
11}
12
13int main(int argc, char* argv[]) {
14  SDL_SetHint(
15    SDL_HINT_WINDOWS_DPI_SCALING, "1");
16  SDL_Init(SDL_INIT_VIDEO);
17  TTF_Init();
18
19  SDL_Window* Window{
20    SDL_CreateWindow(
21      "Text Scaling Demo",
22      SDL_WINDOWPOS_UNDEFINED,
23      SDL_WINDOWPOS_UNDEFINED,
24      800, 200, 0)};
25
26  float Scale{GetDPIScale(Window)};
27
28  // Load font and scale the size based on DPI
29  TTF_Font* Font{
30    TTF_OpenFont(
31      "arial.ttf",
32      int(24 * Scale))}; 
33
34  SDL_Surface* Surface{
35    SDL_GetWindowSurface(Window)};
36  SDL_FillRect(
37    Surface, nullptr,
38    SDL_MapRGB(Surface->format, 255, 255, 255));
39
40  // Render text
41  SDL_Color TextColor{0, 0, 0};
42  SDL_Surface* TextSurface{
43    TTF_RenderText_Blended(
44      Font,
45      "Hello, DPI-aware world!",
46      TextColor)};
47
48  // Calculate position to center the text
49  SDL_Rect Position{
50    (Surface->w - TextSurface->w) / 2,
51    (Surface->h - TextSurface->h) / 2,
52    TextSurface->w,
53    TextSurface->h
54  };
55
56  SDL_BlitSurface(
57    TextSurface, nullptr, Surface, &Position
58  );
59  SDL_UpdateWindowSurface(Window);
60
61  SDL_Event E;
62  bool Running{true};
63  while (Running) {
64    while (SDL_PollEvent(&E)) {
65      if (E.type == SDL_QUIT) Running = false;
66    }
67  }
68
69  TTF_CloseFont(Font);
70  SDL_FreeSurface(TextSurface);
71  SDL_DestroyWindow(Window);
72  TTF_Quit();
73  SDL_Quit();
74  return 0;
75}