我的 SDL_ttf 渲染文本最终被拉伸。我该如何避免呢？

Question

这是我如何呈现 SDL 文本的一个最小示例：

#include <SDL_ttf.h>

void runttf()
{
  constexpr auto SCREEN_WIDTH{300};
  constexpr auto SCREEN_HEIGHT{300};
  constexpr auto font_path = "/usr/share/fonts/truetype/fonts-beng-extra/MuktiNarrow.ttf"; //any font on your system
  constexpr SDL_Rect destination = {10,10,200,80};
  constexpr SDL_Color text_color={0,0,0};

  SDL_Init( SDL_INIT_VIDEO );
  TTF_Init();

  auto window = SDL_CreateWindow( "SDL TTF demo", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN );
  auto renderer = SDL_CreateRenderer( window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC );
  auto font = TTF_OpenFont( font_path, 28 );
  auto textSurface = TTF_RenderText_Solid( font, "I wish I this would not stretch", text_color );
  auto textTexture = SDL_CreateTextureFromSurface(renderer, textSurface);

  SDL_Event e;
  auto run = true;
  while(run) {
    SDL_SetRenderDrawColor(renderer, 0xFF, 0xFF, 0xFF, 0xFF);
    SDL_RenderClear(renderer);
    SDL_RenderCopy(renderer, textTexture, NULL, &destination);
    SDL_RenderPresent(renderer);
    while (SDL_PollEvent(&e) != 0)  if (e.type == SDL_QUIT) run = false;
  }

  SDL_DestroyTexture(textTexture);
  SDL_FreeSurface( textSurface );
  TTF_CloseFont(font);
  SDL_DestroyRenderer( renderer );
  SDL_DestroyWindow( window );
  TTF_Quit();
  SDL_Quit();

}

当我渲染文本时，我最终会得到这样的结果

您可以看到我绘制文本的方式如何使它跨越我要绘制文本的选定区域。我宁愿将文本显示裁剪掉或类似的东西 - 除了拉伸之外的任何东西。

我是否错误地使用了函数？我需要对文本的渲染和放置做更多的数学运算吗？什么是渲染非拉伸文本的规范 sdl ttf 方式？

Answer 1

您正在将 destination 矩形设置为与呈现到表面的文本不同，因此它会拉伸。
您还应该在主循环之前释放表面。
所以我认为你正在寻找的代码：

#include <SDL_ttf.h>

void runttf()
{
    constexpr auto SCREEN_WIDTH{ 300 };
    constexpr auto SCREEN_HEIGHT{ 300 };
    constexpr auto font_path = "/usr/share/fonts/truetype/fonts-beng-extra/MuktiNarrow.ttf"; //any font on your system
    constexpr SDL_Color text_color = { 0,0,0 };

    SDL_Init(SDL_INIT_VIDEO);
    TTF_Init();

    auto window = SDL_CreateWindow("SDL TTF demo", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
    auto renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
    auto font = TTF_OpenFont(font_path, 28);
    auto textSurface = TTF_RenderText_Solid(font, "I wish I this would not stretch", text_color);
    auto textTexture = SDL_CreateTextureFromSurface(renderer, textSurface);
    SDL_Rect destination;
    destination.w = textSurface->w;
    destination.h = textSurface->h;
    destination.x = 0;
    destination.y = 0;
    SDL_FreeSurface(textSurface);

    SDL_Event e;
    auto run = true;
    while (run) {
        SDL_SetRenderDrawColor(renderer, 0xFF, 0xFF, 0xFF, 0xFF);
        SDL_RenderClear(renderer);
        SDL_RenderCopy(renderer, textTexture, NULL, &destination);
        SDL_RenderPresent(renderer);
        while (SDL_PollEvent(&e) != 0)  if (e.type == SDL_QUIT) run = false;
    }

    SDL_DestroyTexture(textTexture);
    TTF_CloseFont(font);
    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    TTF_Quit();
    SDL_Quit();
}

否则我认为代码看起来不错。如果你不关心外观和性能，你可以使用TTF_RenderText_Blended 而不是TTF_RenderText_Solid。