iOS - Setting blurred image on top of other views, odd issues - ios

Question

So, I've got an odd scenario.
In my iOS app, I'm trying to blur the content area of the screen when a popover is opened.
I have this working when using Core Image, but only when using Gaussian blur- none of the other blurs work, which is odd.
I tried doing the same with GPUImage, and it blurs far faster, but doesn't actually put the view on top of the other views!
To summarize: in the source below, setBlurOnView will work properly- however setBlurOnViewWithGPUImage appears to not be working. The blur view (tag 6110) is created, but the app doesn't actually blur.
Note: This is on iOS 6, in the simulator.
Here's the relevant source:
// ScreenBlur.m
#import <QuartzCore/QuartzCore.h>
#import <CoreImage/CoreImage.h>
#import <GPUImage/GPUImage.h>
#import "ScreenBlur.h"
#import "GlobalData.h"
#import "Logger.h"
#implementation ScreenBlur
+ (void) setBlurOnViewWithGPUImage:(UIView*)view {
GPUImagePicture *imageSource = [[GPUImagePicture alloc] initWithImage:[self captureScreenInRect:view.frame inView:view]];
GPUImageGaussianBlurFilter *blur = [[GPUImageGaussianBlurFilter alloc] init];
[imageSource addTarget:blur];
[imageSource processImage];
[self setImage:[imageSource imageFromCurrentlyProcessedOutput] toView:view];
}
+ (void) setBlurOnView:(UIView *)view {
//http://stackoverflow.com/questions/17041669/creating-a-blurring-overlay-view
CIImage *inputImage = [CIImage imageWithCGImage:[self captureScreenInRect:view.frame inView:view].CGImage];
//CIContext *context = [CIContext contextWithOptions:nil];
if ([GlobalData getInstance].ciContext == nil) {
[Logger Log:#"ciContext does not exist, creating..." fromClass:#"ScreenBlur"];
// [GlobalData getInstance].ciContext = [CIContext contextWithOptions:nil]; //cpu context
[GlobalData getInstance].ciContext = [CIContext contextWithEAGLContext:[[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2]];
}
//set up the blur filter
CIFilter *filter = [CIFilter filterWithName:#"CIGaussianBlur"];
[filter setValue:inputImage forKey:kCIInputImageKey];
[filter setValue:[NSNumber numberWithFloat:3.0f] forKey:#"inputRadius"];
CIImage *result = [filter valueForKey:kCIOutputImageKey];
// CIGaussianBlur has a tendency to shrink the image a little,
// this ensures it matches up exactly to the bounds of our original image
CGImageRef cgImage = [[GlobalData getInstance].ciContext createCGImage:result fromRect:[inputImage extent]];
[self setImage:[UIImage imageWithCGImage:cgImage] toView:view];
}
+ (void) setImage:(UIImage*)blurredImage toView:(UIView*)view {
UIView *blurView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, blurredImage.size.width, blurredImage.size.height)];
[blurView setBackgroundColor:[UIColor colorWithPatternImage:blurredImage]];
[blurView setTag:6110];
//set the image as the foreground for the view
[view addSubview:blurView];
[view bringSubviewToFront:blurView];
}
//same as the method above, but resizes the screenshot before applying the blur for increased performance at the expense of image quality.
+ (void) setBlurOnViewPerformanceMode:(UIView *)view {
//http://stackoverflow.com/questions/17041669/creating-a-blurring-overlay-view
UIImage *screenShot = [self imageWithImage:[self captureScreenInRect:view.frame inView:view] scaledToSize:CGSizeMake(view.frame.size.width / 2, view.frame.size.height / 2)];
CIImage *inputImage = [CIImage imageWithCGImage:screenShot.CGImage];
//CIContext *context = [CIContext contextWithOptions:nil];
if ([GlobalData getInstance].ciContext == nil) {
[Logger Log:#"ciContext does not exist, creating..." fromClass:#"ScreenBlur"];
// [GlobalData getInstance].ciContext = [CIContext contextWithOptions:nil]; //cpu context
[GlobalData getInstance].ciContext = [CIContext contextWithEAGLContext:[[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2]];
}
//set up the blur filter
CIFilter *filter = [CIFilter filterWithName:#"CIGaussianBlur"];
[filter setValue:inputImage forKey:kCIInputImageKey];
[filter setValue:[NSNumber numberWithFloat:3.0f] forKey:#"inputRadius"];
CIImage *result = [filter valueForKey:kCIOutputImageKey];
//CGImageRef cgImage = [[GlobalData getInstance].ciContext createCGImage:result fromRect:[inputImage extent]];
CGImageRef cgImage = [[GlobalData getInstance].ciContext createCGImage:result fromRect:[inputImage extent]];
[self setImage:[self imageWithImage:[UIImage imageWithCGImage:cgImage] scaledToSize:view.frame.size] toView:view];
}
+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
//UIGraphicsBeginImageContext(newSize);
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
+ (void) removeBlurFromView:(UIView *)view {
for (UIView *subView in view.subviews) {
if (subView.tag == 6110) {
[subView removeFromSuperview];
}
}
}
+ (UIImage *)captureScreenInRect:(CGRect)captureFrame inView:(UIView*) view {
CALayer *layer;
layer = view.layer;
UIGraphicsBeginImageContext(view.bounds.size);
CGContextClipToRect (UIGraphicsGetCurrentContext(),captureFrame);
[layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *screenImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return screenImage;
}
#end
And then in my view controller, it's simply called with
[ScreenBlur setBlurOnView:self.view];

Answer 1

I found a workaround for this (or, who knows, maybe this is how it was supposed to be done).
//ScreenBlur.m
+ (GPUImageView*) getBlurredImageWithGPUImageFromView:(UIView*)view {
GPUImagePicture *imageSource = [[GPUImagePicture alloc] initWithImage:[self captureScreenInRect:view.frame inView:view] smoothlyScaleOutput:true];
GPUImageFastBlurFilter *blur = [[GPUImageFastBlurFilter alloc] init];
[blur setBlurPasses:3];
[imageSource addTarget:blur];
GPUImageView *filteredView = [[GPUImageView alloc] initWithFrame:view.frame];
[blur addTarget:filteredView];
[imageSource processImage];
return filteredView;
}
//ViewController.m
//blur the main screen
GPUImageView *blurred = [ScreenBlur getBlurredImageWithGPUImageFromView:self.view];
[blurred setTag:6110];
[self.view addSubview:blurred];
[self.view bringSubviewToFront:blurred];