Fix crash when resizing

Author: desertkun

fusepb/views/DisplayOpenGLView.h

@@ -76,6 +76,7 @@
   CVDisplayLinkRef displayLink;
   CGDirectDisplayID mainViewDisplayID;
   BOOL displayLinkRunning;
+  BOOL isResizing;
 }
 +(DisplayOpenGLView *) instance;
 

fusepb/views/DisplayOpenGLView.m

@@ -311,6 +311,7 @@ -(id) initWithFrame:(NSRect)frameRect
   currentScreenTex = 0;
 
   statusbar_updated = NO;
+  isResizing = NO;
 
   [self registerForDraggedTypes:[NSArray arrayWithObjects: NSFilenamesPboardType, nil]];
 
@@ -571,31 +572,48 @@ -(void) drawRect:(NSRect)aRect
 -(void) doReshape
 {
   [view_lock lock];
+  
+  /* Set resize flag to block rendering during reshape */
+  isResizing = YES;
+  
+  /* Stop display link during reshape to prevent drawing with invalid context */
+  [self displayLinkStop];
+  
   NSRect rect;
 
-  [[self openGLContext] makeCurrentContext];
+  NSOpenGLContext *context = [self openGLContext];
+  if (context) {
+    [context makeCurrentContext];
 
-  rect = [self bounds];
+    rect = [self bounds];
 
-  glViewport( 0, 0, (int) rect.size.width, (int) rect.size.height );
+    glViewport( 0, 0, (int) rect.size.width, (int) rect.size.height );
 
-  glMatrixMode( GL_PROJECTION );
-  glLoadIdentity();
+    glMatrixMode( GL_PROJECTION );
+    glLoadIdentity();
 
-  glMatrixMode( GL_MODELVIEW );
-  glLoadIdentity();
-  
-  [[self openGLContext] update];
+    glMatrixMode( GL_MODELVIEW );
+    glLoadIdentity();
+    
+    [context update];
+  }
 
   statusbar_updated = YES;
+  
+  /* Clear resize flag and restart display link after reshape completes */
+  isResizing = NO;
+  [self displayLinkStart];
+  
   [view_lock unlock];
 }
 
 /* scrolled, moved or resized */
 -(void) reshape
 {
   [super reshape];
-  [self performSelectorOnMainThread:@selector(doReshape) withObject:self waitUntilDone:NO];
+  /* Wait for reshape to complete to prevent queuing multiple reshape operations
+     during slow drag resize, which can cause race conditions */
+  [self performSelectorOnMainThread:@selector(doReshape) withObject:self waitUntilDone:YES];
 }
 
 -(void) destroyTexture
@@ -1333,6 +1351,15 @@ -(CVReturn) displayFrame:(const CVTimeStamp *)timeStamp
   int i;
   PIG_dirtytable *workdirty = NULL;
 
+  /* Skip rendering if window is being resized to prevent crashes */
+  [view_lock lock];
+  BOOL resizing = isResizing;
+  [view_lock unlock];
+  
+  if (resizing) {
+    return kCVReturnSuccess;
+  }
+ 
   // Is it possible that while waiting for a lock the emulator is stopped?
   // or already holds the lock? If so give up on updating the frame rather
   // than deadlock on getting the lock - may mean that we miss some screen
@@ -1341,6 +1368,12 @@ -(CVReturn) displayFrame:(const CVTimeStamp *)timeStamp
     return kCVReturnSuccess;
   }
 
+  /* Check if buffered_screen.dirty is initialized - it might be NULL during initialization or cleanup */
+  if( !buffered_screen.dirty ) {
+    [buffered_screen_lock unlock];
+    return kCVReturnSuccess;
+  }
+
   if( buffered_screen.dirty->count == 0 && !statusbar_updated ) {
     [buffered_screen_lock unlock];
     return kCVReturnSuccess;
@@ -1354,6 +1387,20 @@ -(CVReturn) displayFrame:(const CVTimeStamp *)timeStamp
     // occur, also cover the screen texture swap
     [view_lock lock];
 
+    // Double-check resize flag after acquiring lock - resize might have started
+    if (isResizing) {
+      [view_lock unlock];
+      [buffered_screen_lock unlock];
+      return kCVReturnSuccess;
+    }
+
+    // Check if textures are initialized - they may be destroyed during window resize
+    if (!screenTexInitialised) {
+      [view_lock unlock];
+      [buffered_screen_lock unlock];
+      return kCVReturnSuccess;
+    }
+
     if (screenTex[currentScreenTex].dirty)
       pig_dirty_copy( &workdirty, screenTex[currentScreenTex].dirty );