I was wondering if someone could point me in the right direction with this problem.
I have a user-created UIBezierPath with several points that have come about by user touches.
I can get these to create shapes on a bog-standard UIView by using the [myPath fill]; function.
What I would ideally like to do is to use the path to create a clipping mask for a UIImage - perhaps as a UiImageView?
I tried changing my UIView to a UIImageView and then changing the function to [myPath addClip]; but for some reason it does not work.
You need to create a graphics context, draw your image, and draw your mask using kCGBlendModeDestinationIn. Something like this:
UIGraphicsBeginImageContextWithOptions(size, NO, 0.0); // size is a CGSize of the result you want
[image drawInRect:imageRect]; // image is the UIImage you want to clip, imageRect is the rect in the context where you want your image
[mask drawInRect:rect blendMode:kCGBlendModeDestinationIn alpha:1.0]; // mask is a UIImage containing the mask you drew, rect is the rect in the context where you want your mask - could match imageRect above
UIImage* uiImage = UIGraphicsGetImageFromCurrentImageContext();
Related
This is what I want to do:
Take the camera image an put it in a small (not full screen) UIImageView.
Manipulate the image in realtime (e.g. give half of it a red tint).
I have checked around this subject and uncertain as to the best approach. People are recommending both UIImagePickerController and AVCamCaptureManager, or is there something else.
Could I have your advice?
(void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColor(context, CGColorGetComponents([UIColor colorWithRed:0.5 green:0.5 blue:0 alpha:1].CGColor)); // don't make color too saturated
CGContextFillRect(context, rect); // draw base
[[UIImage imageNamed:#"someImage.png"] drawInRect: rect blendMode:kCGBlendModeOverlay alpha:1.0]; // draw image
}
In the rect variable pass the area of the image you would like to tint
I am capturing CGRect with following code. But the resulting image is not the image what i want. Image has some transparent background. What to do for removing transparent background as suggesting the picture.
- (UIImage *)captureScreenInRect:(CGRect)captureFrame {
CALayer *layer;
layer = imageScrollview.layer;
UIGraphicsBeginImageContext(imageScrollview.bounds.size);
CGContextClipToRect (UIGraphicsGetCurrentContext(),captureFrame);
\[layer renderInContext:UIGraphicsGetCurrentContext()\];
UIImage *screenImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return screenImage;
}
Translate your context so that its origin matches your captureFrame:
UIGraphicsBeginImageContext(imageScrollview.bounds.size);
CGContextRef c = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(c, -captureFrame.origin.x, -captureFrame.origin.y);
[imageScrollView.layer renderInContext:c];
UIImage *screenImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
(written from memory, untested)
Additionally clipping the context is not necessary as the image is already clipped by the image context's bounds.
Try this one
CGRect cropRect = CGRectMake(imageScrollview.frame.origin.x+15, imageScrollview.frame.origin.y+15, WIDTH, HEIGHT);
I want to know, how can I erase a custom rect (with, for example, an UIView in IB or something else) of an UIImageView in order to display an other UIImageView positioned underneath.
I didn't manage to do it using some response in the forum...
This will clear a rect in an image:
- (UIImage *)clearRect:(CGRect)rect inImage:(UIImage *)image {
if (UIGraphicsBeginImageContextWithOptions != NULL)
UIGraphicsBeginImageContextWithOptions([image size], NO, 0.0);
else
UIGraphicsBeginImageContext([image size]);
CGContextRef context = UIGraphicsGetCurrentContext();
[image drawInRect:CGRectMake(0.0, 0.0, [image size].width, [image size].height)];
CGContextClearRect(context, rect);
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return result;
}
Just load your image and clear the rects before assigning it to the image view:
UIImage *image = [UIImage imageNamed:#"Image.png"];
UIImage *maskedImage = [self clearRect:CGRectMake(10.0, 10.0, 50.0, 50.0) inImage:image];
[imageView setImage:maskedImage];
probably not the best solution but you can do the other way and take the 4 parts around the rect separately and combine them afterwards without the inner rect. You would repeat this as long as you have rect's to crop out.
You cannot clear the UIImageView itself because this just draws the UIImage. So you have erase the rect in the UIImage. Create a bitmap context, draw the image into it. Erase the part you want to "see through" with CGContextClearRect. When create a new new image from the bitmap context.
How can i take an UIImage and give it a black border programmatically?
If i can receive code, it will be great.
tnx
If you only need to display the border you can do that with Core Animation on the UIImageView's layer. If you need to do it on the image itself then you will need to create a new image, draw the old image into the new image and then draw a rect on top of it.
- (UIImage*)imageWithBorderFromImage:(UIImage*)source;
{
CGSize size = [source size];
UIGraphicsBeginImageContext(size);
CGRect rect = CGRectMake(0, 0, size.width, size.height);
[source drawInRect:rect blendMode:kCGBlendModeNormal alpha:1.0];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor(context, 1.0, 0.5, 1.0, 1.0);
CGContextStrokeRect(context, rect);
UIImage *testImg = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return testImg;
}
This will put a pink border on an image and return the new image.
I'd have a look at this:
Can I Edit the Pixels of the UIImage's Property CGImage
As for the black border part, I assume you can figure that one out. Just iterate along each side and change the pixels to (0,0,0,255) for a certain amount.
Hi all i am having .png image.I want to draw only half of this image.If i call method drawInRect: on image with width being half the size of image,it will still draw the full image
in given rect.So how to draw half image
Before calling -drawInRect, try setting a clip mask on the current context:
UIImage *image = // your image, let's say 100x100
CGRect drawingRect = CGRectMake(0.0f, 0.0f, 100.0f, 100.0f); // adjust the origin; size has to be the image's size
CGRect clippingRect = drawingRect; // copy drawingRect...
clippingRect.size.width = 50.0f; // ...and reduce the width
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context); // save current graphics state
CGContextClipToRect(context, clippingRect);
[image drawInRect:drawingRect];
CGContextRestoreGState(context); // restore previous state (without clip mask)
If it's in a UIImageView, you can change the frame to only fit half the image, then set [imageView setClipsToBounds:YES].
You could crop your existing image by using CGImageCreateWithImageInRect
Clip Rect did the magic. Thanks #thomas
CGContextClipToRect(context, clippingRect);