From 93a520b38500a893b4040b3954813a2311384a07 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Sun, 13 Aug 2017 21:12:14 -0700
Subject: [PATCH] Fixed bug 3605 - Software renderer no longer renders after
 Android screen orientation change

Sylvain

This still happens with the current trunk version.  (software renderer of testdrawchessboard.c)

When there is a rotation, the window size changed and the internal surface is marked as "surface_valid == SDL_FALSE".
And all further call fails.

SDL_video.c :

2478 void
2479 SDL_OnWindowResized(SDL_Window * window)
2480 {
2481     window->surface_valid = SDL_FALSE;
2482     SDL_SendWindowEvent(window, SDL_WINDOWEVENT_SIZE_CHANGED, window->w, window->h);
2483 }

some error set to :
2233         return SDL_SetError("Window surface is invalid, please call SDL_GetWindowSurface() to get a new surface");


So, this seems to be the behavior of the API ...


In the loop() function of testdrawchessboard.c, we can recreate the surface/renderer :

 65        if (e.type == SDL_WINDOWEVENT)
 66        {
 67             if (e.window.event == SDL_WINDOWEVENT_SIZE_CHANGED)
 68             {
 69                surface = SDL_GetWindowSurface(window);
 70                renderer = SDL_CreateSoftwareRenderer(surface);
 71             }
 72             /* Clear the rendering surface with the specified color */
 73             SDL_SetRenderDrawColor(renderer, 0xFF, 0xFF, 0xFF, 0xFF);
 74             SDL_RenderClear(renderer);
 75        }

And it displays correctly.
---
 test/testdrawchessboard.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/test/testdrawchessboard.c b/test/testdrawchessboard.c
index 6aefd48f6..cef8621fc 100644
--- a/test/testdrawchessboard.c
+++ b/test/testdrawchessboard.c
@@ -25,6 +25,7 @@
 
 SDL_Window *window;
 SDL_Renderer *renderer;
+SDL_Surface *surface;
 int done;
 
 void
@@ -59,7 +60,20 @@ loop()
 {
     SDL_Event e;
     while (SDL_PollEvent(&e)) {
-        if (e.type == SDL_QUIT) {
+       
+       /* Re-create when window has been resized */
+       if ((e.type == SDL_WINDOWEVENT) && (e.window.event == SDL_WINDOWEVENT_SIZE_CHANGED)) {
+
+          SDL_DestroyRenderer(renderer);
+
+          surface = SDL_GetWindowSurface(window);
+          renderer = SDL_CreateSoftwareRenderer(surface);
+          /* Clear the rendering surface with the specified color */
+          SDL_SetRenderDrawColor(renderer, 0xFF, 0xFF, 0xFF, 0xFF);
+          SDL_RenderClear(renderer);
+       }
+
+       if (e.type == SDL_QUIT) {
             done = 1;
 #ifdef __EMSCRIPTEN__
             emscripten_cancel_main_loop();
@@ -86,8 +100,6 @@ loop()
 int
 main(int argc, char *argv[])
 {
-    SDL_Surface *surface;
-
     /* Enable standard application logging */
     SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);
 
@@ -100,7 +112,7 @@ main(int argc, char *argv[])
 
 
     /* Create window and renderer for given surface */
-    window = SDL_CreateWindow("Chess Board", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 640, 480, 0);
+    window = SDL_CreateWindow("Chess Board", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 640, 480, SDL_WINDOW_RESIZABLE);
     if(!window)
     {
         SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Window creation fail : %s\n",SDL_GetError());