SDL2播放视频时，窗口大小改变崩溃的解决方案

问题描述及分析

用户在窗口大小改变事件中调用SDL_RenderSetViewport(sdl_renderer, NULL)更新ViewPort

修改SDL源码SDL2\src\render\SDL_render.c

 

static int
SDL_RendererEventWatch(void *userdata, SDL_Event *event)
{
    SDL_Renderer *renderer = (SDL_Renderer *)userdata;

    if (event->type == SDL_WINDOWEVENT) {
        SDL_Window *window = SDL_GetWindowFromID(event->window.windowID);
        if (window == renderer->window) {
            if (renderer->WindowEvent) {
                renderer->WindowEvent(renderer, &event->window);
            }

            if (event->window.event == SDL_WINDOWEVENT_SIZE_CHANGED) {
                /* Make sure we're operating on the default render target */
                SDL_Texture *saved_target = SDL_GetRenderTarget(renderer);
                if (saved_target) {
                    SDL_SetRenderTarget(renderer, NULL);
                }

                if (renderer->logical_w) {
                    UpdateLogicalSize(renderer);
                } else {
                    /* Window was resized, reset viewport */
                    int w, h;

                    if (renderer->GetOutputSize) {
                        renderer->GetOutputSize(renderer, &w, &h);
                    } else {
                        SDL_GetWindowSize(renderer->window, &w, &h);
                    }

                    if (renderer->target) {
                        renderer->viewport_backup.x = 0;
                        renderer->viewport_backup.y = 0;
                        renderer->viewport_backup.w = w;
                        renderer->viewport_backup.h = h;
                    } else {
                        renderer->viewport.x = 0;
                        renderer->viewport.y = 0;
                        renderer->viewport.w = w;
                        renderer->viewport.h = h;
                        // renderer->UpdateViewport(renderer); //注释，改为用户调用
                    }
                }

                if (saved_target) {
                    SDL_SetRenderTarget(renderer, saved_target);
                }
            } else if (event->window.event == SDL_WINDOWEVENT_HIDDEN) {
                renderer->hidden = SDL_TRUE;
            } else if (event->window.event == SDL_WINDOWEVENT_SHOWN) {
                if (!(SDL_GetWindowFlags(window) & SDL_WINDOW_MINIMIZED)) {
                    renderer->hidden = SDL_FALSE;
                }
            } else if (event->window.event == SDL_WINDOWEVENT_MINIMIZED) {
                renderer->hidden = SDL_TRUE;
            } else if (event->window.event == SDL_WINDOWEVENT_RESTORED || 
                       event->window.event == SDL_WINDOWEVENT_MAXIMIZED) {
                if (!(SDL_GetWindowFlags(window) & SDL_WINDOW_HIDDEN)) {
                    renderer->hidden = SDL_FALSE;
                }
            }
        }
    } else if (event->type == SDL_MOUSEMOTION) {
        SDL_Window *window = SDL_GetWindowFromID(event->motion.windowID);
        if (renderer->logical_w && window == renderer->window) {
            event->motion.x -= renderer->viewport.x;
            event->motion.y -= renderer->viewport.y;
            event->motion.x = (int)(event->motion.x / renderer->scale.x);
            event->motion.y = (int)(event->motion.y / renderer->scale.y);
            if (event->motion.xrel > 0) {
                event->motion.xrel = SDL_max(1, (int)(event->motion.xrel / renderer->scale.x));
            } else if (event->motion.xrel < 0) {
                event->motion.xrel = SDL_min(-1, (int)(event->motion.xrel / renderer->scale.x));
            }
            if (event->motion.yrel > 0) {
                event->motion.yrel = SDL_max(1, (int)(event->motion.yrel / renderer->scale.y));
            } else if (event->motion.yrel < 0) {
                event->motion.yrel = SDL_min(-1, (int)(event->motion.yrel / renderer->scale.y));
            }
        }
    } else if (event->type == SDL_MOUSEBUTTONDOWN ||
               event->type == SDL_MOUSEBUTTONUP) {
        SDL_Window *window = SDL_GetWindowFromID(event->button.windowID);
        if (renderer->logical_w && window == renderer->window) {
            event->button.x -= renderer->viewport.x;
            event->button.y -= renderer->viewport.y;
            event->button.x = (int)(event->button.x / renderer->scale.x);
            event->button.y = (int)(event->button.y / renderer->scale.y);
        }
    }
    return 0;
}