renderer: always update the output pixel size at startup

Fixes https://github.com/libsdl-org/SDL/issues/10990

src/render/SDL_render.c

@@ -735,7 +735,9 @@ static void UpdateMainViewDimensions(SDL_Renderer *renderer)
     if (renderer->window) {
         SDL_GetWindowSize(renderer->window, &window_w, &window_h);
     }
-    SDL_GetRenderOutputSize(renderer, &renderer->main_view.pixel_w, &renderer->main_view.pixel_h);
+    SDL_GetRenderOutputSize(renderer, &renderer->output_pixel_w, &renderer->output_pixel_h);
+    renderer->main_view.pixel_w = renderer->output_pixel_w;
+    renderer->main_view.pixel_h = renderer->output_pixel_h;
     if (window_w > 0 && window_h > 0) {
         renderer->dpi_scale.x = (float)renderer->main_view.pixel_w / window_w;
         renderer->dpi_scale.y = (float)renderer->main_view.pixel_h / window_h;
@@ -2565,9 +2567,6 @@ static void UpdateLogicalPresentation(SDL_Renderer *renderer)
     int iwidth, iheight;
     SDL_GetRenderOutputSize(renderer, &iwidth, &iheight);
 
-    renderer->window_pixel_w = iwidth;
-    renderer->window_pixel_h = iheight;
-
     const float output_w = (float)iwidth;
     const float output_h = (float)iheight;
     const float logical_w = renderer->logical_w;
@@ -2702,14 +2701,10 @@ bool SDL_GetRenderLogicalPresentationRect(SDL_Renderer *renderer, SDL_FRect *rec
         if (renderer->logical_presentation_mode == SDL_LOGICAL_PRESENTATION_DISABLED) {
             int output_w = 0, output_h = 0;
 
-            if (!SDL_GetRenderOutputSize(renderer, &output_w, &output_h)) {
-                return false;
-            }
-
             rect->x = 0.0f;
             rect->y = 0.0f;
-            rect->w = (float)output_w;
-            rect->h = (float)output_h;
+            rect->w = (float)renderer->output_pixel_w;
+            rect->h = (float)renderer->output_pixel_h;
         } else {
             SDL_copyp(rect, &renderer->logical_dst_rect);
         }

src/render/SDL_sysrender.h

@@ -250,8 +250,8 @@ struct SDL_Renderer
     SDL_RenderViewState *view;
     SDL_RenderViewState main_view;
 
-    // Cache the window size in pixels
-    int window_pixel_w, window_pixel_h;
+    // Cache the output size in pixels
+    int output_pixel_w, output_pixel_h;
 
     // The window pixel to point coordinate scale
     SDL_FPoint dpi_scale;

src/render/gpu/SDL_render_gpu.c

@@ -976,16 +976,16 @@ static bool GPU_RenderPresent(SDL_Renderer *renderer)
     blit_info.source.w = data->backbuffer.width;
     blit_info.source.h = data->backbuffer.height;
     blit_info.destination.texture = swapchain;
-    blit_info.destination.w = renderer->window_pixel_w;
-    blit_info.destination.h = renderer->window_pixel_h;
+    blit_info.destination.w = renderer->output_pixel_w;
+    blit_info.destination.h = renderer->output_pixel_h;
     blit_info.load_op = SDL_GPU_LOADOP_DONT_CARE;
     blit_info.filter = SDL_GPU_FILTER_LINEAR;
 
     SDL_BlitGPUTexture(data->state.command_buffer, &blit_info);
 
-    if (renderer->window_pixel_w != data->backbuffer.width || renderer->window_pixel_h != data->backbuffer.height || swapchain_fmt != data->backbuffer.format) {
+    if (renderer->output_pixel_w != data->backbuffer.width || renderer->output_pixel_h != data->backbuffer.height || swapchain_fmt != data->backbuffer.format) {
         SDL_ReleaseGPUTexture(data->device, data->backbuffer.texture);
-        CreateBackbuffer(data, renderer->window_pixel_w, renderer->window_pixel_h, swapchain_fmt);
+        CreateBackbuffer(data, renderer->output_pixel_w, renderer->output_pixel_h, swapchain_fmt);
     }
 
 // *** FIXME ***