Add a property to render transparent views.

Container/MPAnimation.h

@@ -11,7 +11,8 @@
 @interface MPAnimation : NSObject
 
 + (UIImage *)renderImageFromView:(UIView *)view;
-+ (UIImage *)renderImageFromView:(UIView *)view withRect:(CGRect)frame;
+
++ (UIImage *)renderImageFromView:(UIView *)view withRect:(CGRect)frame opaque:(BOOL)opaque;
 + (UIImage *)renderImageFromView:(UIView *)view withRect:(CGRect)frame transparentInsets:(UIEdgeInsets)insets;
 + (UIImage *)renderImageForAntialiasing:(UIImage *)image withInsets:(UIEdgeInsets)insets;
 + (UIImage *)renderImageForAntialiasing:(UIImage *)image;

Container/MPAnimation.m

@@ -14,15 +14,15 @@ @implementation MPAnimation
 // Generates an image from the view (view must be opaque)
 + (UIImage *)renderImageFromView:(UIView *)view
 {
-	return [self renderImageFromView:view withRect:view.bounds];
+	return [self renderImageFromView:view withRect:view.bounds opaque:YES];
 }
 
-// Generates an image from the (opaque) view where frame is a rectangle in the view's coordinate space.
+// Generates an image from the view where frame is a rectangle in the view's coordinate space.
 // Pass in bounds to render the entire view, or another rect to render a subset of the view
-+ (UIImage *)renderImageFromView:(UIView *)view withRect:(CGRect)frame
++ (UIImage *)renderImageFromView:(UIView *)view withRect:(CGRect)frame opaque:(BOOL)opaque
 {
     // Create a new context of the desired size to render the image
-	UIGraphicsBeginImageContextWithOptions(frame.size, YES, 0);
+	UIGraphicsBeginImageContextWithOptions(frame.size, opaque, 0);
 	CGContextRef context = UIGraphicsGetCurrentContext();
 
 	// Translate it, to the desired position

Container/MPFlipTransition.h

@@ -17,6 +17,13 @@
 @property (assign, nonatomic) CGFloat coveredPageShadowOpacity;
 @property (assign, nonatomic) CGFloat flippingPageShadowOpacity;
 @property (strong, nonatomic) UIColor *flipShadowColor;
+
+/**
+ * Set it to NO to make MPTransition generate layers with non-opaque background.
+ * Default: YES.
+ */
+@property (nonatomic, assign) BOOL shouldRenderOpaqueViews;
+
 @property (readonly, nonatomic) MPFlipAnimationStage stage;
 @property (assign, nonatomic) CGFloat rubberbandMaximumProgress; // how far up rubberband animation should pull
 

Container/MPFlipTransition.m

@@ -78,6 +78,7 @@ - (id)initWithSourceView:(UIView *)sourceView destinationView:(UIView *)destinat
 		_stage = MPFlipAnimationStage1;
 		_rubberbandMaximumProgress = DEFAULT_RUBBERBAND_MAX_PROGRESS;
 		_shouldRenderAllViews = YES;
+        _shouldRenderOpaqueViews = YES;
 	}
 
 	return self;
@@ -285,10 +286,10 @@ - (void)buildLayers:(BOOL)isResizing
 			break;
 	}
 
-	UIImage *pageFacingImage = drawFacing? [MPAnimation renderImageFromView:self.sourceView withRect:forwards? upperRect : lowerRect] : nil;
+	UIImage *pageFacingImage = drawFacing? [MPAnimation renderImageFromView:self.sourceView withRect:forwards ? upperRect : lowerRect opaque:self.shouldRenderOpaqueViews] : nil;
 
 	UIImage *pageBackImage = isRubberbanding? nil : [MPAnimation renderImageFromView:self.destinationView withRect:forwards? destUpperRect : destLowerRect transparentInsets:insets];
-	UIImage *pageRevealImage = drawReveal? [MPAnimation renderImageFromView:self.destinationView withRect:forwards? destLowerRect : destUpperRect] : nil;
+	UIImage *pageRevealImage = drawReveal? [MPAnimation renderImageFromView:self.destinationView withRect:forwards ? destLowerRect : destUpperRect opaque:self.shouldRenderOpaqueViews] : nil;
 
 	CATransform3D transform = CATransform3DIdentity;