SDL: Send SDL_EVENT_WINDOW_EXPOSED when the GPU renderer swap chain is resized

SDL Commits
1 
From 2b0df96f2582da19eb201a63d1692c8df6ac4df5 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Fri, 29 May 2026 14:33:44 -0700
Subject: [PATCH] Send SDL_EVENT_WINDOW_EXPOSED when the GPU renderer swap
 chain is resized

In this case the current frame being rendered doesn't match the swapchain size and the application should re-render the frame.

Fixes https://github.com/libsdl-org/SDL/issues/15550
---
 src/render/gpu/SDL_render_gpu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/render/gpu/SDL_render_gpu.c b/src/render/gpu/SDL_render_gpu.c
index b9b267324fa51..0884d686ca115 100644
--- a/src/render/gpu/SDL_render_gpu.c
+++ b/src/render/gpu/SDL_render_gpu.c
@@ -22,6 +22,7 @@
 
 #ifdef SDL_VIDEO_RENDER_GPU
 
+#include "../../events/SDL_windowevents_c.h"
 #include "../../video/SDL_pixels_c.h"
 #include "../SDL_d3dmath.h"
 #include "../SDL_sysrender.h"
@@ -1517,6 +1518,9 @@ static bool GPU_RenderPresent(SDL_Renderer *renderer)
 
             if (swapchain_texture_width != data->backbuffer.width || swapchain_texture_height != data->backbuffer.height) {
                 CreateBackbuffer(data, swapchain_texture_width, swapchain_texture_height, SDL_GetGPUSwapchainTextureFormat(data->device, renderer->window));
+
+                // Notify the application that it needs to redraw this frame
+                SDL_SendWindowEvent(renderer->window, SDL_EVENT_WINDOW_EXPOSED, 0, 0);
             }
         } else {
             SDL_SubmitGPUCommandBuffer(data->state.command_buffer);