I have a UIView whose layer has two sublayers, each of which has a 1.5 pixel border around the outside. I am trying to create a UIImage from this view with the following code
UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, 0.0f);
[self drawViewHierarchyInRect:self.bounds afterScreenUpdates:NO];
UIImage * image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
The code does return a UIImage, but the image is clipped – that is, the image doesn't include the all of the borders on the sublayers. I've tried tweaking the sizes/bounds but to no effect. Any suggestions of what else I might try?
Thanks!
What happens if you send the parent layer a
drawInContext: message instead of telling the view to draw itself?
Related
The images that goes through here are PNGs of different shapes with a transparent background. In addition to merging them (which works fine), I'd like to give the new image a couple of pixels thick outline. But I can't seem to manage that.
(So just to clarify, I'm after an outline around the actual shapes in the context, not a rectangle around the entire image.)
+ (UIImage *)mergeBackgroundImage:(UIImage *)backgroundImage withOverlayingImage:(UIImage *)overlayImage{
UIGraphicsBeginImageContextWithOptions(backgroundImage.size, NO, backgroundImage.scale);
[backgroundImage drawInRect:CGRectMake(0, 0, backgroundImage.size.width, backgroundImage.size.height)];
[overlayImage drawInRect:CGRectMake(backgroundImage.size.width - overlayImage.size.width, backgroundImage.size.height - overlayImage.size.height, overlayImage.size.width, overlayImage.size.height)];
//Add stroke.
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return result;
}
Thanks for your time!
Markus
If you make a CALayer who's backing is set to a CGImage of your image, you can then use it as a masking layer for your layer that requires an outline1. And once you've done that, you can render your layer into another context, and then get another UIImage from that.
// edit: Something like what's describe in this answer.
From what I've read, iOS7's new drawViewHierarchyInRect is supposed to be faster than CALayer's renderInContext. And according to this and this, it should be a simple matter of calling:
[myView drawViewHierarchyInRect:myView.frame afterScreenUpdates:YES];
instead of
[myView.layer renderInContext:UIGraphicsGetCurrentContext()];
However, when I try this, I just get blank images. Full code that does the capture, where "self" is a subclass of UIView,
// YES = opaque. Ignores alpha channel, so less memory is used.
// This method for some reasons renders the
UIGraphicsBeginImageContextWithOptions(self.bounds.size, YES, self.window.screen.scale); // Still slow.
if ( [AIMAppDelegate isOniOS7OrNewer] )
[self drawViewHierarchyInRect:self.frame afterScreenUpdates:YES]; // Doesn't work!
else
[self.layer renderInContext:UIGraphicsGetCurrentContext()]; // Works!
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
contentImageView.image = image; // this is empty if done using iOS7's way
and contentImageView is a UIImageView that is added as a subView to self during initialization.
Additionally, the drawing that I want captured in the image is contained in other sub-views that are also added to self as a sub-view during initialization (including contentImageView).
Any ideas why this is failing when using drawViewHierarchyInRect?
* Update *
I get an image if I draw a specific sub-view, such as:
[contentImageView drawViewHierarchyInRect:contentImageView.frame afterScreenUpdates:YES];
or
[self.curvesView drawViewHierarchyInRect:self.curvesView.frame afterScreenUpdates:YES];
however I need all the visible sub-views combined into one image.
Try it with self.bounds rather than self.frame—it’s possible you’re getting an image of your view rendered outside the boundaries of the image context you’ve created.
I have a transparent image and a UIView below and same size with the image. Everytime I want to change color of the image, I just set color to the UIView. My problem is how can I save the decorated image to the photo library? Since the color/decoration comes from the UIView below, not the image.
Thanks guy for reading.
You can get screen shot of a view by this method:
+ (UIImage *) getScreenShot : (UIView *) view{
UIGraphicsBeginImageContext(view.frame.size);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *screenImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return screenImage;
}
Pass your baseView in this method it'll return the decorated image.
I'm trying to make a transition between two ViewControllers. My Transition class has a property for the destination view controller. When I try to get a screenshot of the destination's view, I use this method:
+ (UIImage *)renderImageFromView:(UIView *)view withRect:(CGRect)frame {
// Create a new context the size of the frame
UIGraphicsBeginImageContextWithOptions(frame.size, YES, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
// Render the view
[view.layer renderInContext:context];
// Get the image from the context
UIImage *renderedImage = UIGraphicsGetImageFromCurrentImageContext();
// Cleanup the context you created
UIGraphicsEndImageContext();
return renderedImage;
}
So when I want the image, I'll do this:
UIImage *image = [UIImage renderImageFromView:destinationController.view withRect:destinationController.view.bounds];
I tried it on a blank UIViewController with an orange background color and a label. I get the orange background color, but I do not get the label that was created in IB. Is there a way to get a proper screenshot of the new view I plan on showing? Thanks!
You need to make sure the view's layer is drawn to first. Calling renderInContext on a CALayer will only recursively call additional child CALayers. You need your child UIViews to draw themselves, not just using the CALayer.
Try calling
[view drawrect:frame];
instead of
[view.layer renderInContext:context];
As long as you have an open graphics context(which you do at that point), drawrect should draw directly into that.
I've got two UIImageView: the first one is laying on the top of the other (eg. an overlay).
I want now to take a screenshot of the whole thing.
Note that before that step, I allow the user to change the overlay by panning,scaling and ROTATING it, so I must keep track of his editing.
So, here's the homework:
rotating the context basing on the view's transform rotation value
positioning on the origin, where the user finished to pan the overlay
calculate the size of the overlay view (it's always a rectangle, however!)
I'm gonna merge them inside a similar piece of code:
UIGraphicsBeginImageContext...
...
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
but... what does "best fit" instead of the "..."?
Example code is well accepted!
Thanks
UIGraphicsBeginImageContext(firstImage.size);
[firstImage drawAtPoint:CGPointMake(0,0)];
[secondImage drawAtPoint:CGPointMake(0,0)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();