Fix race conditions when rotating the view.

If you rotate the screen while pages are being rendered, they will arrive
at the wrong size, and will have to be reloaded. We must take care not to
mess up the currently displayed image view, since the new rendering may
arrive in the middle of a rotation animation.

1 files changed, 133 insertions, 121 deletions

diff --git a/ios/main.m b/ios/main.m
index f205d64a..1112ae1f 100644
--- a/ios/main.m
+++ b/ios/main.m
@@ -1,5 +1,7 @@
 #import <UIKit/UIKit.h>
 
+// TODO: [[UIScreen mainScreen] scale]; -- for retina iphone 4 displays we want double resolution!
+
 #undef ABS
 #undef MIN
 #undef MAX
@@ -38,14 +40,14 @@ static fz_glyph_cache *glyphcache = NULL;
 	UIActivityIndicatorView *loadingView;
 	pdf_xref *xref;
 	int number;
-	int cancel;
+	BOOL cancel;
 }
 - (id) initWithFrame: (CGRect)frame xref: (pdf_xref*)aXref page: (int)aNumber;
 - (void) displayImage: (UIImage*)image;
+- (void) resizeImage;
 - (void) loadPage;
-- (void) onRotate;
-- (void) resetZoom;
-- (void) resetZoomAnimated;
+- (void) willRotate;
+- (void) resetZoomAnimated: (BOOL)animated;
 - (int) number;
 @end
 
@@ -66,15 +68,13 @@ static fz_glyph_cache *glyphcache = NULL;
 	int scroll_animating; // stop view updates during scrolling animations
 }
 - (id) initWithFile: (NSString*)filename;
-- (void) layoutPageViews;
-- (void) rotatePageViews;
 - (void) createPageView: (int)number;
 - (void) gotoPage: (int)number animated: (BOOL)animated;
-- (void) onTap: (UITapGestureRecognizer*)sender;
+- (void) onShowOutline: (id)sender;
 - (void) onSlide: (id)sender;
-- (void) showOutline: (id)sender;
-- (void) hideNavigationBar;
+- (void) onTap: (UITapGestureRecognizer*)sender;
 - (void) showNavigationBar;
+- (void) hideNavigationBar;
 @end
 
 @interface MuAppDelegate : NSObject <UIApplicationDelegate, UINavigationControllerDelegate>
@@ -230,7 +230,6 @@ static UIImage *renderPage(pdf_xref *xref, int number, CGSize screen)
 
 - (void) viewWillDisappear: (BOOL)animated
 {
-	[self setTitle: @"Library"];
 	printf("library viewWillDisappear (stopping reload timer)\n");
 	[timer invalidate];
 	timer = nil;
@@ -305,6 +304,7 @@ static UIImage *renderPage(pdf_xref *xref, int number, CGSize screen)
 {
 	MuDocumentController *document = [[MuDocumentController alloc] initWithFile: filename];
 	if (document) {
+		[self setTitle: @"Library"];
 		[[self navigationController] pushViewController: document animated: YES];
 		[document release];
 	}
@@ -390,12 +390,15 @@ static UIImage *renderPage(pdf_xref *xref, int number, CGSize screen)
 	if (self) {
 		xref = aXref;
 		number = aNumber;
+		cancel = NO;
 
 		[self setShowsVerticalScrollIndicator: NO];
 		[self setShowsHorizontalScrollIndicator: NO];
 		[self setDecelerationRate: UIScrollViewDecelerationRateFast];
 		[self setDelegate: self];
 
+		[self resetZoomAnimated: NO];
+
 		// TODO: use a one shot timer to delay the display of this?
 		loadingView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
 		[loadingView startAnimating];
@@ -408,7 +411,6 @@ static UIImage *renderPage(pdf_xref *xref, int number, CGSize screen)
 
 - (void) dealloc
 {
-	printf("pageview dealloc (%d)\n", number);
 	[loadingView release];
 	[imageView release];
 	[super dealloc];
@@ -429,11 +431,10 @@ static UIImage *renderPage(pdf_xref *xref, int number, CGSize screen)
 {
 	if (number < 0 || number >= pdf_count_pages(xref))
 		return;
-	cancel = NO;
 	dispatch_async(queue, ^{
 		if (!cancel) {
 			printf("loading page %d\n", number);
-			UIImage *image = renderPage(xref, number, [self bounds].size);
+			UIImage *image = renderPage(xref, number, self.bounds.size);
 			dispatch_async(dispatch_get_main_queue(), ^{
 				[self displayImage: image];
 				[image release];
@@ -453,46 +454,58 @@ static UIImage *renderPage(pdf_xref *xref, int number, CGSize screen)
 
 - (void) displayImage: (UIImage*)image
 {
-	[loadingView removeFromSuperview];
-	[loadingView release];
-	loadingView = nil;
-
-	[imageView removeFromSuperview];
-	[imageView release];
-	imageView = nil;
-
-	// TODO: if rotated during loading the size won't be as expected
-	// TODO: ... and what to do about zooming ...
-	// TODO: [[UIScreen mainScreen] scale]; -- for retina iphone 4 displays we want double resolution!
+	if (loadingView) {
+		[loadingView removeFromSuperview];
+		[loadingView release];
+		loadingView = nil;
+	}
 
-	[self resetZoomAnimated: NO];
+	if (!imageView) {
+		imageView = [[UIImageView alloc] initWithImage: image];
+		[self addSubview: imageView];
+	} else {
+		[imageView setImage: image];
+	}
 
-	imageView = [[UIImageView alloc] initWithImage: image];
-	[self addSubview: imageView];
-	[self setContentSize: [imageView frame].size];
+	[self resizeImage];
 }
 
-- (void) onRotate
+- (void) resizeImage
 {
-	[self resetZoomAnimated: NO];
+	if (imageView) {
+		CGSize imageSize = imageView.image.size;
+		CGSize scale = fitPageToScreen(imageSize, self.bounds.size);
+		if (fabs(scale.width - 1) > 0.1) {
+			CGRect frame = [imageView frame];
+			frame.size.width = imageSize.width * scale.width;
+			frame.size.height = imageSize.height * scale.height;
+			[imageView setFrame: frame];
 
-	CGSize imageSize = [[imageView image] size];
-	CGSize scale = fitPageToScreen(imageSize, [self bounds].size);
-	if (fabs(scale.width - 1) > 0.1) {
-printf("image size is off, reloading (%d)\n", number);
-		[self loadPage];
-		CGRect frame = [imageView frame];
-		frame.size.width = imageSize.width * scale.width;
-		frame.size.height = imageSize.height * scale.height;
-		[imageView setFrame: frame];
-	} else {
-		[imageView sizeToFit];
-	}
+			printf("resized view; queuing up a reload (%d)\n", number);
+			dispatch_async(queue, ^{
+				dispatch_async(dispatch_get_main_queue(), ^{
+					CGSize scale = fitPageToScreen(imageView.image.size, self.bounds.size);
+					if (fabs(scale.width - 1) > 0.1)
+						[self loadPage];
+				});
+			});
+		} else {
+			[imageView sizeToFit];
+		}
 
-	[self setContentSize: [imageView frame].size];
+		[self setContentSize: imageView.frame.size];
 
-	[self setNeedsLayout];
-	[self layoutIfNeeded];
+//		[self setNeedsLayout];
+		[self layoutIfNeeded];
+	}
+}
+
+- (void) willRotate
+{
+	if (imageView) {
+		[self resetZoomAnimated: NO];
+		[self resizeImage];
+	}
 }
 
 - (void) layoutSubviews
@@ -575,7 +588,7 @@ printf("image size is off, reloading (%d)\n", number);
 		[[self navigationItem] setRightBarButtonItem:
 			[[UIBarButtonItem alloc]
 				initWithBarButtonSystemItem: UIBarButtonSystemItemBookmarks
-				target:self action:@selector(showOutline:)]];
+				target:self action:@selector(onShowOutline:)]];
 	}
 	[titles release];
 	[pages release];
@@ -633,6 +646,30 @@ printf("image size is off, reloading (%d)\n", number);
 	[view release];
 }
 
+- (void) viewDidUnload
+{
+	[visiblePages release]; visiblePages = nil;
+	[recycledPages release]; recycledPages = nil;
+	[indicator release]; indicator = nil;
+	[slider release]; slider = nil;
+	[wrapper release]; wrapper = nil;
+	[canvas release]; canvas = nil;
+}
+
+- (void) dealloc
+{
+	if (xref) {
+		pdf_xref *self_xref = xref; // don't auto-retain self here!
+		dispatch_async(queue, ^{
+			printf("close xref\n");
+			pdf_free_xref(self_xref);
+		});
+	}
+	[outline release];
+	[key release];
+	[super dealloc];
+}
+
 - (void) viewWillAppear: (BOOL)animated
 {
 	CGSize size = [canvas frame].size;
@@ -656,7 +693,7 @@ printf("image size is off, reloading (%d)\n", number);
 
 - (void) viewDidAppear: (BOOL)animated
 {
-	[self layoutPageViews];
+	[self scrollViewDidScroll: canvas];
 }
 
 - (void) viewWillDisappear: (BOOL)animated
@@ -666,25 +703,21 @@ printf("image size is off, reloading (%d)\n", number);
 	[[self navigationController] setToolbarHidden: YES animated: animated];
 }
 
-- (void) viewDidUnload
+- (void) showNavigationBar
 {
-	[visiblePages release]; visiblePages = nil;
-	[recycledPages release]; recycledPages = nil;
-	[indicator release]; indicator = nil;
-	[slider release]; slider = nil;
-	[wrapper release]; wrapper = nil;
-	[canvas release]; canvas = nil;
-}
+	if ([[self navigationController] isNavigationBarHidden]) {
+		[[self navigationController] setNavigationBarHidden: NO];
+		[[self navigationController] setToolbarHidden: NO];
+		[indicator setHidden: NO];
 
-- (void) dealloc
-{
-	if (xref) {
-		printf("close xref\n");
-		pdf_free_xref(xref);
+		[UIView beginAnimations: @"MuNavBar" context: NULL];
+
+		[[[self navigationController] navigationBar] setAlpha: 1];
+		[[[self navigationController] toolbar] setAlpha: 1];
+		[indicator setAlpha: 1];
+
+		[UIView commitAnimations];
 	}
-	[outline release];
-	[key release];
-	[super dealloc];
 }
 
 - (void) hideNavigationBar
@@ -709,21 +742,9 @@ printf("image size is off, reloading (%d)\n", number);
 	[indicator setHidden: YES];
 }
 
-- (void) showNavigationBar
+- (void) onShowOutline: (id)sender
 {
-	if ([[self navigationController] isNavigationBarHidden]) {
-		[[self navigationController] setNavigationBarHidden: NO];
-		[[self navigationController] setToolbarHidden: NO];
-		[indicator setHidden: NO];
-
-		[UIView beginAnimations: @"MuNavBar" context: NULL];
-
-		[[[self navigationController] navigationBar] setAlpha: 1];
-		[[[self navigationController] toolbar] setAlpha: 1];
-		[indicator setAlpha: 1];
-
-		[UIView commitAnimations];
-	}
+	[[self navigationController] pushViewController: outline animated: YES];
 }
 
 - (void) onSlide: (id)sender
@@ -735,6 +756,26 @@ printf("image size is off, reloading (%d)\n", number);
 		[self gotoPage: number animated: NO];
 }
 
+- (void) onTap: (UITapGestureRecognizer*)sender
+{
+	CGPoint p = [sender locationInView: canvas];
+	CGPoint ofs = [canvas contentOffset];
+	float x0 = (width - GAP) / 5;
+	float x1 = (width - GAP) - x0;
+	p.x -= ofs.x;
+	p.y -= ofs.y;
+	if (p.x < x0) {
+		[self gotoPage: current-1 animated: YES];
+	} else if (p.x > x1) {
+		[self gotoPage: current+1 animated: YES];
+	} else {
+		if ([[self navigationController] isNavigationBarHidden])
+			[self showNavigationBar];
+		else
+			[self hideNavigationBar];
+	}
+}
+
 - (void) scrollViewWillBeginDragging: (UIScrollView *)scrollView
 {
 	[self hideNavigationBar];
@@ -753,18 +794,15 @@ printf("image size is off, reloading (%d)\n", number);
 
 	[[NSUserDefaults standardUserDefaults] setInteger: current forKey: key];
 
-	[self layoutPageViews];
-
 	[indicator setText: [NSString stringWithFormat: @" %d of %d ", current+1, pdf_count_pages(xref)]];
 	[slider setValue: current];
-}
 
-- (void) layoutPageViews
-{
+	// swap the page views in and out
+
 	for (MuPageView *view in visiblePages) {
 		if ([view number] != current)
 			[view resetZoomAnimated: YES];
-		if ([view number] < current - 2 || [view number] > current + 2) {
+		if ([view number] < current - 1 || [view number] > current + 1) {
 			[recycledPages addObject: view];
 			[view removeFromSuperview];
 		}
@@ -777,18 +815,6 @@ printf("image size is off, reloading (%d)\n", number);
 	[self createPageView: current + 1];
 }
 
-- (void) rotatePageViews
-{
-	for (MuPageView *view in visiblePages)
-		[view setFrame: CGRectMake([view number] * width, 0, width-GAP, height)];
-	for (MuPageView *view in visiblePages)
-		if ([view number] == current)
-			[view onRotate];
-	for (MuPageView *view in visiblePages)
-		if ([view number] != current)
-			[view onRotate];
-}
-
 - (void) createPageView: (int)number
 {
 	if (number < 0 || number >= pdf_count_pages(xref))
@@ -868,7 +894,18 @@ printf("image size is off, reloading (%d)\n", number);
 	[canvas setContentSize: CGSizeMake(pdf_count_pages(xref) * max_width, height)];
 	[canvas setContentOffset: CGPointMake(current * width, 0)];
 
-	[self rotatePageViews];
+	for (MuPageView *view in visiblePages) {
+		if ([view number] == current) {
+			[view setFrame: CGRectMake([view number] * width, 0, width-GAP, height)];
+			[view willRotate];
+		}
+	}
+	for (MuPageView *view in visiblePages) {
+		if ([view number] != current) {
+			[view setFrame: CGRectMake([view number] * width, 0, width-GAP, height)];
+			[view willRotate];
+		}
+	}
 }
 
 - (void) didRotateFromInterfaceOrientation: (UIInterfaceOrientation)o
@@ -877,31 +914,6 @@ printf("image size is off, reloading (%d)\n", number);
 	[canvas setContentOffset: CGPointMake(current * width, 0)];
 }
 
-- (void) onTap: (UITapGestureRecognizer*)sender
-{
-	CGPoint p = [sender locationInView: canvas];
-	CGPoint ofs = [canvas contentOffset];
-	float x0 = (width - GAP) / 5;
-	float x1 = (width - GAP) - x0;
-	p.x -= ofs.x;
-	p.y -= ofs.y;
-	if (p.x < x0) {
-		[self gotoPage: current-1 animated: YES];
-	} else if (p.x > x1) {
-		[self gotoPage: current+1 animated: YES];
-	} else {
-		if ([[self navigationController] isNavigationBarHidden])
-			[self showNavigationBar];
-		else
-			[self hideNavigationBar];
-	}
-}
-
-- (void) showOutline: (id)sender
-{
-	[[self navigationController] pushViewController: outline animated: YES];
-}
-
 @end
 
 #pragma mark -