二、基于QT

本章目标：

1. RGB与YUV的原理
2. SDL渲染图像的方法
3. QT渲染图像的方法
4. SDL与QT结合渲染图像的方法
5. 刷新SDL渲染的方式
6. 面向对象工厂模式封装方法
7. 窗口大小的变化与抗锯齿的处理

RGB像素格式原理

RGB与YUV像素格式基础

1. 渲染RGB像素格式

1.1 通过SDL渲染SDL窗口

1. 创建SDL的窗口、渲染器、纹理
2. 创建RGB图像数据
3. 纹理通过渲染器渲染RGB数据到窗口

#include <iostream>
#include <sdl/SDL.h>
using namespace std;
#pragma comment(lib,SDL2.lib)
#undef main
int main(int argc, char* ar[])
{int w = 800;int h = 600;//1 初始化SDL video库if (SDL_Init(SDL_IIT_VIDEO)){cout << SDL_GetError() << endl;return -1;}//2 生成SDL 窗口auto screen = SDL_CreateWindow(test sdl ffmpeg,SDL_WIDOWPOS_CETERED,//窗口位置SDL_WIDOWPOS_CETERED,w,h,SDL_WIDOW_OPEGL|SDL_WIDOW_RESIZABLE);if (!screen){cout << SDL_GetError() << endl;return -2;}// 生成渲染器auto render = SDL_CreateRenderer(screen, -1, SDL_REDERER_ACCELERATED);if (!render){cout << SDL_GetError() << endl;return -;}//4 生成材质auto texture = SDL_CreateTexture(render, SDL_PIXELFORMAT_ARGB8888,SDL_TEXTUREACCESS_STREAMIG,// 可加锁w, h);if (!texture){cout << SDL_GetError() << endl;return -4;}// 存放图像的数据shared_ptr<unsigned char> rgb(new unsigned char[w * h * 4]);auto r = rgb.get();unsigned char tmp = 255;for (;;){//判断退出SDL_Event ev;SDL_WaitEventTimeout(&ev, 10);if ( == SDL_QUIT){SDL_DestroyWindow(screen);break;}tmp--;for (int j = 0; j < h; j){int b = j * w * 4;for (int i = 0; i < w*4; i = 4){r[b  i] = 0;           //Br[b  i  1] = 0;       //Gr[b  i  2] = tmp;     //Rr[b  i  ] = 0;       //A}}//5 内存数据写入材质SDL_UpdateTexture(texture, ULL, r, w * 4);//6 清理屏幕SDL_RenderClear(render);SDL_Rect sdl_rect;sdl_rect.x = 0;sdl_rect.y = 0;sdl_rect.w = w;sdl_rect.h = h;//7 复制材质到渲染器SDL_RenderCopy(render, texture,ULL,//原图位置和尺寸ULL//&sdl_rect//目标位置和尺寸);//8 渲染SDL_RenderPresent(render);}getchar();return 0;
}

1.2 通过SDL渲染QT控件、通过定时器刷新渲染窗口

1. 创建QT Lebel控件，及设置其标题、尺寸等属性
2. SDL的窗口创建参数改自定义为Leble控件
3. 重载定时器处理事件，内容为渲染图像
4. 设置并启动定时器

#include sdlqtrgb.h
#include <sdl/SDL.h>
#pragma comment(lib,SDL2.lib)
static SDL_Window* sdl_win = ULL;
static SDL_Renderer* sdl_render = ULL;
static SDL_Texture* sdl_texture = ULL;
static int sdl_width = 0;
static int sdl_height = 0;
static unsigned  char* rgb = ULL;
static int pix_size = 4;
void SdlQtRGB::timerEvent(QTimerEvent* ev)
{static unsigned char tmp = 255;tmp--;for (int j = 0; j < sdl_height; j){int b = j * sdl_width* pix_size;for (int i = 0; i < sdl_width * pix_size; i = pix_size){rgb[b  i] = 0;         //Brgb[b  i  1] = tmp;   //Grgb[b  i  2] = 0;     //Rrgb[b  i  ] = 0;     //A}}SDL_UpdateTexture(sdl_texture, ULL, rgb, sdl_width * pix_size);SDL_RenderClear(sdl_render);SDL_Rect rect;rect.x = 0;rect.y = 0;rect.w = sdl_width;rect.h = sdl_height;SDL_RenderCopy(sdl_render,sdl_texture,ULL,&rect);SDL_RenderPresent(sdl_render);
}SdlQtRGB::SdlQtRGB(QWidget *parent): QWidget(parent)
{ui.setupUi(this);sdl_width = ui.label->width();sdl_height = ui.label->height();//初始化SDLSDL_Init(SDL_IIT_VIDEO);//创建窗口sdl_win = SDL_CreateWindowFrom((void*)ui.label->winId());//创建渲染器sdl_render = SDL_CreateRenderer(sdl_win, -1, SDL_REDERER_ACCELERATED);//创建材质sdl_texture = SDL_CreateTexture(sdl_render,SDL_PIXELFORMAT_ARGB8888,SDL_TEXTUREACCESS_STREAMIG,sdl_width,sdl_height);rgb = new unsigned char[sdl_width * sdl_height * pix_size];startTimer(10);
}

1. 合并两幅RGB图像

1. 重新定义要渲染的纹理大小：宽为两张图相加，高为最高的图高度。
2. 遍历两张图片的每一行，将B图片的第n行像素拷贝到A图片的第n行之后
3. 保存合并的图片，并渲染显示。

#include sdlqtrgb.h
#include <QMessageBox>
#include <sdl/SDL.h>
#pragma comment(lib,SDL2.lib)
static SDL_Window* sdl_win = ULL;
static SDL_Renderer* sdl_render = ULL;
static SDL_Texture* sdl_texture = ULL;
static int sdl_width = 0;
static int sdl_height = 0;
static unsigned  char* rgb = ULL;
static int pix_size = 4;
void SdlQtRGB::timerEvent(QTimerEvent* ev)
{static unsigned char tmp = 255;tmp--;for (int j = 0; j < sdl_height; j){int b = j * sdl_width* pix_size;for (int i = 0; i < sdl_width * pix_size; i = pix_size){//rgb[b  i] = 0;         //B//rgb[b  i  1] = tmp;   //G//rgb[b  i  2] = 0;     //R//rgb[b  i  ] = 0;     //A}}SDL_UpdateTexture(sdl_texture, ULL, rgb, sdl_width * pix_size);SDL_RenderClear(sdl_render);SDL_Rect rect;rect.x = 0;rect.y = 0;rect.w = sdl_width;rect.h = sdl_height;SDL_RenderCopy(sdl_render,sdl_texture,ULL,&rect);SDL_RenderPresent(sdl_render);
}SdlQtRGB::SdlQtRGB(QWidget *parent): QWidget(parent)
{ui.setupUi(this);sdl_width = ui.label->width();sdl_height = ui.label->height();//初始化SDLSDL_Init(SDL_IIT_VIDEO);//创建窗口sdl_win = SDL_CreateWindowFrom((void*)ui.label->winId());//创建渲染器sdl_render = SDL_CreateRenderer(sdl_win, -1, SDL_REDERER_ACCELERATED);QImage img1(001.png);QImage img2(002.png);if (img1.isull() || img2.isull()){QMessageBox::information(this, , open image failed!);return;}int out_w = img1.width()  img2.width();int out_h = img1.height();if (out_h < img2.height())out_h = img2.height();sdl_width = out_w;sdl_height = out_h;resize(sdl_width, sdl_height);ui.label->move(0, 0);ui.label->resize(sdl_width, sdl_height);//创建材质sdl_texture = SDL_CreateTexture(sdl_render,SDL_PIXELFORMAT_ARGB8888,SDL_TEXTUREACCESS_STREAMIG,sdl_width,sdl_height);rgb = new unsigned char[sdl_width * sdl_height * pix_size];//默认设置为透明memset(rgb, 0, sdl_width * sdl_height * pix_size);//合并两幅图像for (int i = 0; i < sdl_height; i){int b = i * sdl_width * pix_size;if (i < img1.height())memcpy(rgb  b, img1.scanLine(i), img1.width() * pix_size);b = img1.width() * pix_size;if (i < img2.height())memcpy(rgb  b, img2.scanLine(i), img2.width() * pix_size);}QImage out(rgb, sdl_width, sdl_height, QImage::Format_ARGB2);out.save(out.png);startTimer(10);
}

2. 渲染YUV像素格式

2.1 通过刷新渲染来播放YUV数据

注意：渲染YUV与渲染RGB的区别

1. 读取YUV数据时的数据量与YUV不同
2. 更新纹理时，每一行的数据两也不同
3. 上面的区别主要因为RGB与YUV再内存中的存储方式不同。

#include sdlqtrgb.h
#include <sdl/SDL.h>
#include <fstream>
#include <QMessageBox>
using namespace std;
#pragma comment(lib,SDL2.lib)
static SDL_Window* sdl_win = ULL;
static SDL_Renderer* sdl_render = ULL;
static SDL_Texture* sdl_texture = ULL;
static int sdl_width = 0;
static int sdl_height = 0;
static unsigned  char* yuv = ULL;
static int pix_size = 2;
static ifstream yuv_file;
void SdlQtRGB::timerEvent(QTimerEvent* ev)
{yuv_file.read((char*)yuv, sdl_width * sdl_height * 1.5);//yuv 平面存储存储// yyyyyyyy uu vvSDL_UpdateTexture(sdl_texture, ULL, yuv, sdl_width  //一行 y的字节数);SDL_RenderClear(sdl_render);SDL_Rect rect;rect.x = 0;rect.y = 0;rect.w = sdl_width;rect.h = sdl_height;SDL_RenderCopy(sdl_render,sdl_texture,ULL,&rect);SDL_RenderPresent(sdl_render);
}SdlQtRGB::SdlQtRGB(QWidget *parent): QWidget(parent)
{//打开yuv文件yuv_(400_00_25.yuv, ios::binary);if (!yuv_file){QMessageBox::information(this, , open yuv failed!);return;}ui.setupUi(this);sdl_width = 400; sdl_height = 00;ui.label->resize(sdl_width, sdl_height);//初始化SDLSDL_Init(SDL_IIT_VIDEO);//创建窗口sdl_win = SDL_CreateWindowFrom((void*)ui.label->winId());//创建渲染器sdl_render = SDL_CreateRenderer(sdl_win, -1, SDL_REDERER_ACCELERATED);//创建材质 支持YUVsdl_texture = SDL_CreateTexture(sdl_render,SDL_PIXELFORMAT_IYUV,SDL_TEXTUREACCESS_STREAMIG,sdl_width,sdl_height);yuv = new unsigned char[sdl_width * sdl_height * pix_size];startTimer(10);
}

2.2 随窗口自动缩放、抗锯齿、SDL窗口退出

自动缩放画面
需要搞清楚窗口、Qt label、SDL_Rect之间的关系

1. 窗口可以根据Qt Label来创建，也可以通过SDL自定义窗口
2. 若是根据Qt的winId创建的窗口，则渲染画面显示在窗口中；若SDL自定义的窗口，则渲染在单独画面，而不是再自定义的窗口中
3. SDL_Rect的大小代表画面的大小，ULL表示渲染全部。
4. Qt Lable只有通过winId创建的窗口才有效，代表渲染的尺寸。
   若是根据Qt的winId创建的窗口：创建一个resize事件处理函数，当触发时，让lable的大小随窗口的大小变化，让SDL_Rect为ULL，画面就会随着label大小变化，lable也随着窗口大小变化，实现画面随着窗口大小变化；也可以让QtLable和SDL_Rect的width和height都随窗口的大小直接变化。
   若是SDL自定义的窗口：渲染画面与窗口不在同一个窗口，而且QtLable无意义，所以直接让SDL_Rect为ULL即可。因为二者不是在同一个窗口，所以虽然可以让SDL_Rect的width和height随着自定义窗口变化，但无法控制SDL_Rect本身渲染的窗口大小。
   抗锯齿：在创建纹理之前，设置渲染的质量
   SDL窗口退出：若是根据QtWinID创建的窗口，退出时可直接窗口；但SDL自定义的窗口和渲染窗口不是一个窗口，因此点击渲染窗口退出无效，只有点击自定义窗口才能推出。为了解决这个问题，可以通过SDL事件来解决，当sdl的事件是退出事件时，就销毁创建的窗口、渲染器、纹理。

#include sdlqtrgb.h
#include <sdl/SDL.h>
#include <fstream>
#include <iostream>
#include <QMessageBox>
using namespace std;
#pragma comment(lib,SDL2.lib)
static SDL_Window* sdl_win = ULL;
static SDL_Renderer* sdl_render = ULL;
static SDL_Texture* sdl_texture = ULL;
static int sdl_width = 0;
static int sdl_height = 0;
static unsigned  char* yuv = ULL;
static int pix_size = 2;
static ifstream yuv_file;
static bool isExit;void SdlQtRGB::timerEvent(QTimerEvent* ev)
{if (isExit){return;}//SDL窗口推出SDL_Event qev;SDL_WaitEventTimeout(&qev, 1);if (q == SDL_QUIT){SDL_DestroyTexture(sdl_texture);sdl_texture = nullptr;SDL_DestroyRenderer(sdl_render);sdl_render = nullptr;SDL_DestroyWindow(sdl_win);sdl_win = nullptr;isExit = true;return;}yuv_file.read((char*)yuv, sdl_width * sdl_height * 1.5);//yuv 平面存储存储// yyyyyyyy uu vvSDL_UpdateTexture(sdl_texture, ULL, yuv, sdl_width  //一行 y的字节数);SDL_RenderClear(sdl_render);//SDL_Rect rect;//rect.x = 0;//rect.y = 0;//rect.w = sdl_width;//rect.h = sdl_height;//随窗口自动缩放画面SDL_RenderCopy(sdl_render,sdl_texture,ULL, ULL);SDL_RenderPresent(sdl_render);
}void SdlQtRGB::resizeEvent(QResizeEvent* ev)
{ui.label->move(0, 0);ui.label->resize(size());
}SdlQtRGB::SdlQtRGB(QWidget *parent): QWidget(parent)
{//打开yuv文件yuv_(400_00_25.yuv, ios::binary);if (!yuv_file){QMessageBox::information(this, , open yuv failed!);return;}ui.setupUi(this);sdl_width = 400; sdl_height = 00;ui.label->move(0, 0);ui.label->resize(size());//初始化SDLSDL_Init(SDL_IIT_VIDEO);//抗锯齿SDL_SetHint(SDL_HIT_REDER_SCALE_QUALITY, 1);//创建窗口//sdl_win = SDL_CreateWindowFrom((void*)ui.label->winId());sdl_win = SDL_CreateWindow(,SDL_WIDOWPOS_CETERED,SDL_WIDOWPOS_CETERED,sdl_width, sdl_height,SDL_WIDOW_OPEGL | SDL_WIDOW_RESIZABLE);//创建渲染器sdl_render = SDL_CreateRenderer(sdl_win, -1, SDL_REDERER_ACCELERATED);//创建材质 支持YUVsdl_texture = SDL_CreateTexture(sdl_render,SDL_PIXELFORMAT_IYUV,SDL_TEXTUREACCESS_STREAMIG,sdl_width,sdl_height);yuv = new unsigned char[sdl_width * sdl_height * pix_size];isExit = false;startTimer(10);
}

. 面向对象封装