c_cpp iOS：UIImagePickerController编辑视图圆叠加

Posted 2021-05-14

/** 
Credit: I've started by reading this SO question: http://stackoverflow.com/questions/20794187/uiimagepickercontroller-editing-view-circle-overlay-edited

Trick to add a circle view on image picker editing to facilitate circular cropping
Tested on iPhone4s, iPhone5, iPhone6, iPhone6+, iPad - iOS 7 and iOS 8 - on May 2015
**/

#pragma mark - UINavigationControllerDelegate

- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    if ([navigationController.viewControllers count] == 3 && ([[[[navigationController.viewControllers objectAtIndex:2] class] description] isEqualToString:@"PUUIImageViewController"] || [[[[navigationController.viewControllers objectAtIndex:2] class] description] isEqualToString:@"PLUIImageViewController"]))
    {
        [self addCircleOverlayToImagePicker:viewController];
    }
}

#pragma mark - Circle overlay trick

-(void)addCircleOverlayToImagePicker:(UIViewController*)viewController
{
    UIColor *circleColor = [UIColor clearColor];
    UIColor *maskColor = [[UIColor blackColor] colorWithAlphaComponent:0.8];
    
    CGFloat screenHeight = [[UIScreen mainScreen] bounds].size.height;
    CGFloat screenWidth = [[UIScreen mainScreen] bounds].size.width;
    
    UIView *plCropOverlayCropView; //The default crop view, we wan't to hide it and show our circular one
    UIView *plCropOverlayBottomBar; //On iPhone is the bar with "cancel" and "choose" button, on Ipad is an Image View with a label saying "Scale and move"
    
    //Subviews hirearchy is different in iPad/iPhone:
    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad){
        
        plCropOverlayCropView = [viewController.view.subviews objectAtIndex:1];
        plCropOverlayBottomBar = [[[[viewController.view subviews] objectAtIndex:1] subviews] objectAtIndex:1];
        
        //Protect against iOS changes...
        if (! [[[plCropOverlayCropView class] description] isEqualToString:@"PLCropOverlay"]){
            DDLogWarn(@"Image Picker with circle overlay: PLCropOverlay not found");
            return;
        }
        if (! [[[plCropOverlayBottomBar class] description] isEqualToString:@"UIImageView"]){
            DDLogWarn(@"Image Picker with circle overlay: PLCropOverlayBottomBar not found");
            return;
        }
    }
    else{
        plCropOverlayCropView = [[[viewController.view.subviews objectAtIndex:1] subviews] firstObject];
        plCropOverlayBottomBar = [[[[viewController.view subviews] objectAtIndex:1] subviews] objectAtIndex:1];

        //Protect against iOS changes...
        if (! [[[plCropOverlayCropView class] description] isEqualToString:@"PLCropOverlayCropView"]){
            DDLogWarn(@"Image Picker with circle overlay: PLCropOverlayCropView not found");
            return;
        }
        if (! [[[plCropOverlayBottomBar class] description] isEqualToString:@"PLCropOverlayBottomBar"]){
            DDLogWarn(@"Image Picker with circle overlay: PLCropOverlayBottomBar not found");
            return;
        }
    }
    
    //It seems that everything is ok, we found the CropOverlayCropView and the CropOverlayBottomBar
    
    plCropOverlayCropView.hidden = YES; //Hide default CropView
    
    CAShapeLayer *circleLayer = [CAShapeLayer layer];
    //Center the circleLayer frame:
    UIBezierPath *circlePath = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0.0f, screenHeight/2 - screenWidth/2, screenWidth, screenWidth)];
    circlePath.usesEvenOddFillRule = YES;
    circleLayer.path = [circlePath CGPath];
    circleLayer.fillColor = circleColor.CGColor;
    //Mask layer frame: it begins on y=0 and ends on y = plCropOverlayBottomBar.origin.y
    UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, screenWidth, screenHeight- plCropOverlayBottomBar.frame.size.height) cornerRadius:0];
    [maskPath appendPath:circlePath];
    maskPath.usesEvenOddFillRule = YES;
    
    CAShapeLayer *maskLayer = [CAShapeLayer layer];
    maskLayer.path = maskPath.CGPath;
    maskLayer.fillRule = kCAFillRuleEvenOdd;
    maskLayer.fillColor = maskColor.CGColor;
    [viewController.view.layer addSublayer:maskLayer];
    
    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone){
        //On iPhone add an hint label on top saying "scale and move" or whatever you want
        UILabel *cropLabel = [[UILabel alloc]initWithFrame:CGRectMake(0, 10, screenWidth, 50)];
        [cropLabel setText:NSLocalizedString(@"IMAGE_PICKER_CROP_LABEL", nil)];
        [cropLabel setTextAlignment:NSTextAlignmentCenter];
        [cropLabel setTextColor:[UIColor whiteColor]];
        [viewController.view addSubview:cropLabel];
    }
    else{ //On iPad re-add the overlayBottomBar with the label "scale and move" because we set its parent to hidden (it's a subview of PLCropOverlay)
        [viewController.view addSubview:plCropOverlayBottomBar];
    }        
}