前言

SDL中內置加載BMP的API，使用起來會更加簡單，便于初學者學習使用SDL

如果需要加載JPG、PNG等其他格式的圖片，可以使用第三方庫：SDL_image

測試環境：

• ffmpeg的4.3.2自行編譯版本
• windows環境
• qt5.12
• sdl2.0.22（mingw編譯器）

完整代碼：

SdlShowBmpThread.h

#ifndef SDLSHOWBMPTHREAD_H
#define SDLSHOWBMPTHREAD_H#include <QObject>
#include <QThread>class SdlShowBmpThread : public QThread
{Q_OBJECT
public:explicit SdlShowBmpThread(QObject *parent = nullptr);~SdlShowBmpThread();signals:// QThread interface
protected:virtual void run() override;
};#endif // SDLSHOWBMPTHREAD_H

SdlShowBmpThread.cpp

#include "sdlshowbmpthread.h"#include <QDebug>
#include <SDL2/SDL.h>#define END(judge, func) \if (judge) { \qDebug() << #func << "error" << SDL_GetError(); \goto end; \}SdlShowBmpThread::SdlShowBmpThread(QObject *parent) : QThread(parent)
{// 當監聽到線程結束時（finished），就調用deleteLater回收內存connect(this,&SdlShowBmpThread::finished,this,[=](){this->deleteLater();qDebug()<<"SdlPlayWavThread線程結束";});
}SdlShowBmpThread::~SdlShowBmpThread()
{// 斷開所有的連接disconnect();// 內存回收之前，正常結束線程requestInterruption();// 安全退出quit();wait();qDebug() << this << "析構（內存被回收）";
}void SdlShowBmpThread::run()
{// 像素數據SDL_Surface *surface = nullptr;// 窗口SDL_Window *window = nullptr;// 渲染上下文SDL_Renderer *renderer = nullptr;// 紋理（直接跟特定驅動程序相關的像素數據）SDL_Texture *texture = nullptr;// 矩形框SDL_Rect srcRect = {0, 0, 1928, 1048};  //源圖片從0,0坐標截取1928*1048尺寸大小的圖片SDL_Rect dstRect = {0, 0, 1928, 1048};  //目標圖片在0,0左邊顯示1928*1048大小的圖片SDL_Rect rect;// 初始化子系統END(SDL_Init(SDL_INIT_VIDEO), SDL_Init);// 加載BMPsurface = SDL_LoadBMP("E:/media/picture-test.bmp");END(!surface, SDL_LoadBMP);// 創建窗口window = SDL_CreateWindow(// 標題"SDL顯示BMP圖片",// xSDL_WINDOWPOS_UNDEFINED,// ySDL_WINDOWPOS_UNDEFINED,// wsurface->w,// hsurface->h,SDL_WINDOW_SHOWN);END(!window, SDL_CreateWindow);// 創建渲染上下文renderer = SDL_CreateRenderer(window, -1,SDL_RENDERER_ACCELERATED |SDL_RENDERER_PRESENTVSYNC);if (!renderer) {renderer = SDL_CreateRenderer(window, -1, 0);END(!renderer, SDL_CreateRenderer);}// 創建紋理texture = SDL_CreateTextureFromSurface(renderer, surface);END(!texture, SDL_CreateTextureFromSurface);// 畫一個紅色的矩形框END(SDL_SetRenderDrawColor(renderer,255, 0, 0, SDL_ALPHA_OPAQUE),SDL_SetRenderDrawColor);rect = {0, 0, 50, 50};END(SDL_RenderFillRect(renderer, &rect),SDL_RenderFillRect);// 設置繪制顏色（畫筆顏色）END(SDL_SetRenderDrawColor(renderer,255, 255, 0, SDL_ALPHA_OPAQUE),SDL_SetRenderDrawColor);// 用繪制顏色（畫筆顏色）清除渲染目標END(SDL_RenderClear(renderer),SDL_RenderClear);// 拷貝紋理數據到渲染目標（默認是window）END(SDL_RenderCopy(renderer, texture, &srcRect, &dstRect),SDL_RenderCopy);// 更新所有的渲染操作到屏幕上SDL_RenderPresent(renderer);SDL_Delay(2000);end:SDL_FreeSurface(surface);SDL_DestroyTexture(texture);SDL_DestroyRenderer(renderer);SDL_DestroyWindow(window);SDL_Quit();
}

線程調用：

void MainWindow::on_pushButton_sdl_show_bmp_clicked()
{m_pSdlShowBmpThread=new SdlShowBmpThread(this);m_pSdlShowBmpThread->start();
}

注意：.h文件中提前聲明了以下全局變量

	SdlShowBmpThread *m_pSdlShowBmpThread=nullptr;

注意：本文為個人記錄，新手照搬可能會出現各種問題，請謹慎使用

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