_coursrach/testSDL/Lesson2/main.cpp

#include <SDL2/SDL.h>
#include <iostream>
using namespace std;

const int screen_width = 640;
const int scren_height = 480;
SDL_Window* win = NULL;
SDL_Renderer* ren = NULL;

SDL_Texture* LoadImage(const char* path)
{
    SDL_Surface* loadedImage = NULL;
    SDL_Texture* texture = NULL;
    loadedImage = SDL_LoadBMP(path);
    if (loadedImage != 0)
    {
        texture = SDL_CreateTextureFromSurface(ren, loadedImage);
        SDL_FreeSurface(loadedImage);
    }
    else 
        cout << SDL_GetError() << endl; 
    return texture;
}

void ApplySurfaces(int x, int y, SDL_Texture* tex, SDL_Renderer* ren)
{
    SDL_Rect pos;
    pos.x = x;
    pos.y = y;
    SDL_QueryTexture(tex, NULL, NULL, &pos.w, &pos.h);  //Функция заполнит pos.w и pos.h для формата текстуры 1:1
    SDL_RenderCopy(ren, tex, NULL, &pos);   //В нужной точке рисуем текстуру с оригинальной высотой и шириной
}

int main()
{
                            if (SDL_Init(SDL_INIT_EVERYTHING) == -1)
                            {
                                cout << SDL_GetError() << endl;
                                return 1;
                            }
    win = SDL_CreateWindow("Lesson 2", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, screen_width, scren_height, SDL_WINDOW_SHOWN);
                            if (win == NULL)
                            {
                                cout << SDL_GetError() << endl;
                                return 2;
                            }
    ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
                            if (ren == NULL)
                            {
                                cout << SDL_GetError() << endl;
                                return 3;
                            }
    SDL_Texture *background = NULL, *image = nullptr;
    image = LoadImage("./image.bmp");
    background = LoadImage("./background.bmp");
                            if (image == NULL || background == NULL)
                            {
                                cout << "bad LoadImage\n";
                                return 4;
                            }
    SDL_RenderClear(ren);

    int bW, bH;
    SDL_QueryTexture(background, NULL, NULL, &bW, &bH);
    cout << bW << " " << bH << endl;
    ApplySurfaces( 0, 0, background, ren);
    ApplySurfaces( bW, 0, background, ren);
    ApplySurfaces( 0, bH, background, ren);
    ApplySurfaces( bW, bH, background, ren);

    int iW, iH;
    SDL_QueryTexture(image, NULL, NULL, &iW, &iH);
    int x = (screen_width - iW) / 2;
    int y = (scren_height - iH) / 2;

    ApplySurfaces(x, y, image, ren);
    SDL_RenderPresent(ren);
    
    SDL_Delay(10000);

    SDL_DestroyTexture(background);
    SDL_DestroyTexture(image);
    SDL_DestroyRenderer(ren);
    SDL_DestroyWindow(win);
    
    SDL_Quit();
    return 0;
}