Use DosBox::Rect methods in assertions

src/gui/render.cpp

@@ -611,8 +611,8 @@ bool RENDER_MaybeAutoSwitchShader([[maybe_unused]] const DosBox::Rect canvas_siz
 	// uninitialised VideoMode param with width and height set to 0 which
 	// results in a crash. The proper fix is to make the init sequence 100%
 	// identical on all platforms, but in the interim this workaround will do.
-	if (canvas_size_px.w == 0 || canvas_size_px.h == 0 ||
-	    video_mode.width == 0 || video_mode.height == 0) {
+	if (canvas_size_px.IsEmpty() || video_mode.width == 0 ||
+	    video_mode.height == 0) {
 		return false;
 	}
 

src/gui/sdlmain.cpp

@@ -734,8 +734,9 @@ static DosBox::Rect get_canvas_size_in_pixels(
 		SDL_GetWindowSize(sdl.window, &canvas_size_px.w, &canvas_size_px.h);
 	}
 #endif
-	assert(canvas_size_px.w > 0 && canvas_size_px.h > 0);
-	return to_rect(canvas_size_px);
+	const auto r = to_rect(canvas_size_px);
+	assert(r.HasPositiveSize());
+	return r;
 }
 
 // Logs the source and target resolution including describing scaling method
@@ -761,7 +762,7 @@ static void log_display_properties(const int render_width_px,
 	}();
 
 	assert(render_width_px > 0 && render_height_px > 0);
-	assert(draw_size_px.w > 0.0f && draw_size_px.h > 0.0f);
+	assert(draw_size_px.HasPositiveSize());
 
 	const auto scale_x = static_cast<double>(draw_size_px.w) / render_width_px;
 	const auto scale_y = static_cast<double>(draw_size_px.h) / render_height_px;