我的 SDL_ttf 呈现的文本最终被拉伸我该如何避免？

问题描述

以下是我如何呈现 SDL 文本的最小示例：

#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};

  SDL_Init( SDL_INIT_VIDEO );
  TTF_Init();

  auto window = SDL_CreateWindow( "SDL TTF demo",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);
    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东西

您可以看到我绘制文本的方式如何使它在我想要绘制文本的选定区域上拉伸。我宁愿将文本显示裁剪掉或类似的东西 - 任何东西都不要拉伸。

我是否错误地使用了函数？我是否需要对文本的呈现和放置进行更多的数学计算？渲染非拉伸文本的规范 sdl ttf 方式是什么？

解决方法

您将 destination 矩形设置为与渲染到表面的文本不同，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 };

    SDL_Init(SDL_INIT_VIDEO);
    TTF_Init();

    auto window = SDL_CreateWindow("SDL TTF demo",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);
        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。如果您不太关心性能而不是外观，则可以使用 TTF_RenderText_Blended 而不是 TTF_RenderText_Solid。