C: Linux C 编程 - SDL图像处理

图像处理

YUV图像

YUV图像是一种采用YUV颜色空间来表示图像中的每个像素。这个就像用RGB颜色空间来图像中的每个像素那样。一个是Y，U，V三个分量，一个是R，G，B三个分量。

 

YUV图像相比其他图像要大的多，我一张原始的100多K的jpg图像文件，同样大小转换为YUV图像后500多K。一张原始的10几M的mp4视频文件，同样大小转换为YUV视频后1.3个多G。

 

显示YUV图像

此程序支持显示yuv420p，yuvj420p格式的YUV图像。其他格式的YUV图像没测试。

#include<stdio.h>
#include<SDL_video.h>
#include<SDL_render.h>
#include<SDL_surface.h>
#include<SDL_events.h>

int main(int argc, char **argv)
{
  char *filename = "H:\\huacao-pix_fmt_yuvj420p-320x180.yuv"; // "H:\\huacao-pix_fmt_yuvj420p-320x180.yuv"; // "H:\\huacao-pix_fmt_yuvj420p-1024x680.yuv"; // "H:\\huacao-pix_fmt_yuv420p-320x180.yuv";
  FILE *fp = NULL;
  
  SDL_Window *pWin;
  int width = 640;
  int height = 360;

  SDL_Renderer *renderer;
  SDL_Texture *texture;
  SDL_Rect rect;

  int pix_width = 320;
  int pix_height = 180;
  int bpp = 12;

  unsigned char *buf;
  int buf_size;

  SDL_Event e;
  int exit = 0;
  pWin = SDL_CreateWindow("Player", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, width, height, SDL_WINDOW_RESIZABLE); // SDL_WINDOW_FULLSCREEN, SDL_WINDOW_RESIZABLE
  if (pWin == NULL)
  {
    fprintf(stderr, "create window err.\n");
    return 1;
  }

  renderer = SDL_CreateRenderer(pWin, -1, 0);
  if (renderer == NULL) 
  {
    fprintf(stderr, "create renderer err: %s\n", SDL_GetError());
    return 1;
  }

  texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_IYUV, SDL_TEXTUREACCESS_STREAMING, pix_width, pix_height);
  if (texture == NULL) 
  {
    fprintf(stderr, "create texture err: %s\n", SDL_GetError());
    return 1;
  }

  fp = fopen(filename, "rb+");
  if (fp == NULL) 
  {
    fprintf(stderr, "open err: %s\n", filename);
    return 1;
  }

  buf_size = pix_width * pix_height * bpp / 8;
  buf = (unsigned char *) malloc(buf_size + 1);

  if (fread(buf, buf_size, 1, fp) != 1) 
  {
    fprintf(stderr, "read err: %s\n", filename);
    return 1;
  }
  SDL_UpdateTexture(texture, NULL, buf, pix_width);
  rect.x = 0;
  rect.y = 0;
  rect.w = width;
  rect.h = height;

  SDL_RenderClear(renderer);
  SDL_RenderCopy(renderer, texture, NULL, &rect);
  SDL_RenderPresent(renderer);

  while (! exit)
  {
    while (SDL_PollEvent(&e))
    {
      if (e.type == SDL_QUIT)
      {
        exit = 1;
      }
    }
  }

  SDL_DestroyWindow(pWin);
  SDL_Quit();
  return 0;
}

BMP图像

显示BMP图像

#include<stdio.h>
#include<SDL_video.h>
#include<SDL_render.h>
#include<SDL_surface.h>
#include<SDL_events.h>

int main(int argc, char **argv)
{
  SDL_Window *pWin;
  SDL_Renderer *renderer;
  SDL_Surface *bmp;
  SDL_Texture *texture;

  SDL_Event e;
  int exit = 0;
  pWin = SDL_CreateWindow("SDL", 100, 100, 500, 500, SDL_WINDOW_RESIZABLE); // SDL_WINDOW_FULLSCREEN, SDL_WINDOW_RESIZABLE
  if (pWin == NULL)
  {
    fprintf(stderr, "create window err.\n");
    return 1;
  }
  renderer = SDL_CreateRenderer(pWin, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
  if (renderer == NULL) 
  {
    fprintf(stderr, "create renderer err: %s\n", SDL_GetError());
    return 1;
  }

  bmp = SDL_LoadBMP("huacao.bmp");
  if (bmp == NULL) 
  {
    fprintf(stderr, "load bmp err: %s\n", SDL_GetError());
    return 1;
  }

  texture = SDL_CreateTextureFromSurface(renderer, bmp);
  if (texture == NULL) 
  {
    fprintf(stderr, "create texture err: %s\n", SDL_GetError());
    return 1;
  }

  SDL_FreeSurface(bmp);

  SDL_RenderClear(renderer);

  SDL_RenderCopy(renderer, texture, NULL, NULL);

  SDL_RenderPresent(renderer);

  while (! exit)
  {
  
    while (SDL_PollEvent(&e))
    {
      if (e.type == SDL_QUIT)
      {
        exit = 1;
        
      }
      else if (e.type == SDL_WINDOWEVENT)
      {
        if (e.window.event == SDL_WINDOWEVENT_RESIZED)
        {
         
        }
        else if (e.window.event == SDL_WINDOWEVENT_SIZE_CHANGED)
        {
        }
      }
    }
  }

  SDL_DestroyTexture(texture);
  SDL_DestroyRenderer(renderer);

  SDL_DestroyWindow(pWin);
  SDL_Quit();
  return 0;
}