From 1a5b1701b83760c068ab4943060577030fcdc3fe Mon Sep 17 00:00:00 2001
From: fherzog2 <fherzog2@users.noreply.github.com>
Date: Thu, 8 Jun 2017 01:08:25 +0200
Subject: [PATCH] Fix deadlock in Windows version of viewflif. The window was
 being resized in a non-GUI thread, which is not allowed.

---
 src/viewflif.c | 37 ++++++++++++++++++++++++++++---------
 1 file changed, 28 insertions(+), 9 deletions(-)

diff --git a/src/viewflif.c b/src/viewflif.c
index 97a8949f..ac4de4b0 100644
--- a/src/viewflif.c
+++ b/src/viewflif.c
@@ -51,6 +51,10 @@ int* frame_delay = NULL;
 
 SDL_mutex *volatile mutex;
 
+Uint32 RESIZE_TO_IMAGE_EVENTTYPE = (Uint32)-1;
+int image_size_w = 0;
+int image_size_h = 0;
+
 int window_size_set = 0;
 int framecount = 0;
 
@@ -103,6 +107,14 @@ int do_event(SDL_Event e) {
     if (e.type == SDL_KEYDOWN && e.key.keysym.sym == SDLK_q) {printf("Quit\n"); quit=1; return 0;}
     // refresh the window if its size changes
     if (e.type == SDL_WINDOWEVENT && e.window.event == SDL_WINDOWEVENT_SIZE_CHANGED && renderer) { draw_image(); }
+    if (RESIZE_TO_IMAGE_EVENTTYPE != (Uint32)-1 && e.type == RESIZE_TO_IMAGE_EVENTTYPE){
+        if (e.user.code == 0){
+            SDL_SetWindowSize(window,image_size_w,image_size_h);
+            SDL_SetWindowPosition(window,SDL_WINDOWPOS_CENTERED,SDL_WINDOWPOS_CENTERED);
+        }
+        else
+            SDL_MaximizeWindow(window);
+    }
     return 1;
 }
 
@@ -121,15 +133,20 @@ bool updateTextures(uint32_t quality, int64_t bytes_read) {
     char title[100];
     sprintf(title,"FLIF image decoded at %ux%u [read %lli bytes, quality=%.2f%%]",w,h,(long long int) bytes_read, 0.01*quality);
     SDL_SetWindowTitle(window,title);
-    if (!window_size_set) {
-      int ww = (w > dm.w ? dm.w : w);
-      int wh = (h > dm.h ? dm.h : h);
-      if (ww > w * wh / h) ww = wh * w / h;
-      else if (ww < w * wh / h) wh = ww * h / w;
-      if (w > dm.w*8/10 && h > dm.h*8/10) { ww = ww*8/10; wh = wh*8/10; }
-      SDL_SetWindowSize(window,ww,wh);
-      SDL_SetWindowPosition(window,SDL_WINDOWPOS_CENTERED,SDL_WINDOWPOS_CENTERED);
-      if (w > dm.w*8/10 && h > dm.h*8/10) { SDL_MaximizeWindow(window); }
+    if (!window_size_set && RESIZE_TO_IMAGE_EVENTTYPE != (Uint32)-1) {
+      int image_size_w = (w > dm.w ? dm.w : w);
+      int image_size_h = (h > dm.h ? dm.h : h);
+      if (image_size_w > w * image_size_h / h) image_size_w = image_size_h * w / h;
+      else if (image_size_w < w * image_size_h / h) image_size_h = image_size_w * h / w;
+      if (w > dm.w*8/10 && h > dm.h*8/10) { image_size_w = image_size_w*8/10; image_size_h = image_size_h*8/10; }
+
+      // On Windows, a window cannot be resized from a non-GUI thread.
+      // Therefore delegate the resize to the event loop.
+      SDL_Event resize_to_image_event;
+      resize_to_image_event.type = RESIZE_TO_IMAGE_EVENTTYPE;
+      resize_to_image_event.user.code = (w > dm.w*8/10 && h > dm.h*8/10); // do_maximize flag
+
+      SDL_PushEvent(&resize_to_image_event);
       window_size_set = 1;
     }
 
@@ -281,6 +298,8 @@ int main(int argc, char **argv) {
       return 1;
     }
 
+    RESIZE_TO_IMAGE_EVENTTYPE = SDL_RegisterEvents(1);
+
 #ifdef PROGRESSIVE_DECODING
     last_preview_time = (-2*preview_interval* CLOCKS_PER_SEC);
 #endif