How to blend two images by changing alfa of only one image so that the upper image will be slightly transparent and the above image will be displayed as it is drawn on the background image.
You can do it through imageView alpha property
imageView.alpha = 0.0f;
Detailed code:
UIImage *bottomImage = [UIImage imageNamed:#"bottomImage.png"];
UIImage *topImage = [UIImage imageNamed:#"topImage.png"];
CGSize newSize = CGSizeMake(width, height);
UIGraphicsBeginImageContext( newSize );
// Use existing opacity as is
[bottomImage drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
// Apply supplied opacity
[topImage drawInRect:CGRectMake(0,0,newSize.width,newSize.height) blendMode:kCGBlendModeNormal alpha:0.8];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
see more details here
I'm trying to create an image for a custom style UIButton using an image from the camera roll on iPhone. The button has a circular background and effectively appears as a circle. Now I need an image to go in the middle of the button that also appears round.
How do I cut a square UIImage to appear round with transparency outside of the round area?
If masking is involved, do I need to pre-render a mask or can I create one programmatically(ex: a circle)?
Thank you!
I have never done anything like that, but try using QuartzCore framework and its' cornerRadius property. Example:
#import <QuartzCore/QuartzCore.h>
//some other code ...
UIImageView *imgView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, 100, 100)];
imgView.layer.cornerRadius = 10.0f;
play around with it a bit and you will get what you want.
Hope it helps
Yes you can use CoreGraphics to draw the mask dynamically.
Then you can create the masked image.
Example for masking:
- (UIImage*) maskImage:(UIImage *)image withMask:(UIImage *)maskImage
{
CGImageRef maskRef = maskImage.CGImage;
CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef),
CGImageGetHeight(maskRef),
CGImageGetBitsPerComponent(maskRef),
CGImageGetBitsPerPixel(maskRef),
CGImageGetBytesPerRow(maskRef),
CGImageGetDataProvider(maskRef), NULL, false);
CGImageRef maskedImageRef = CGImageCreateWithMask([image CGImage], mask);
UIImage *maskedImage = [UIImage imageWithCGImage:maskedImageRef];
CGImageRelease(maskedImageRef);
CGImageRelease(mask);
return maskedImage;
}
I started looking into this a couple of weeks back. I tried all the suggestions here, none of which worked well. In the great tradition of RTFM I went and read Apple's documentation on Quartz 2D Programming and came up with this. Please try it out and let me know how you go.
The code could be fairly easily altered to crop to an elipse, or any other shape defined by a path.
Make sure you include Quartz 2D in your project.
#include <math.h>
+ (UIImage*)circularScaleNCrop:(UIImage*)image: (CGRect) rect{
// This function returns a newImage, based on image, that has been:
// - scaled to fit in (CGRect) rect
// - and cropped within a circle of radius: rectWidth/2
//Create the bitmap graphics context
UIGraphicsBeginImageContextWithOptions(CGSizeMake(rect.size.width, rect.size.height), NO, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
//Get the width and heights
CGFloat imageWidth = image.size.width;
CGFloat imageHeight = image.size.height;
CGFloat rectWidth = rect.size.width;
CGFloat rectHeight = rect.size.height;
//Calculate the scale factor
CGFloat scaleFactorX = rectWidth/imageWidth;
CGFloat scaleFactorY = rectHeight/imageHeight;
//Calculate the centre of the circle
CGFloat imageCentreX = rectWidth/2;
CGFloat imageCentreY = rectHeight/2;
// Create and CLIP to a CIRCULAR Path
// (This could be replaced with any closed path if you want a different shaped clip)
CGFloat radius = rectWidth/2;
CGContextBeginPath (context);
CGContextAddArc (context, imageCentreX, imageCentreY, radius, 0, 2*M_PI, 0);
CGContextClosePath (context);
CGContextClip (context);
//Set the SCALE factor for the graphics context
//All future draw calls will be scaled by this factor
CGContextScaleCTM (context, scaleFactorX, scaleFactorY);
// Draw the IMAGE
CGRect myRect = CGRectMake(0, 0, imageWidth, imageHeight);
[image drawInRect:myRect];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
Include the following code in your UIView class replacing "monk2.png" with your own image name.
- (void)drawRect:(CGRect)rect
{
UIImage *originalImage = [UIImage imageNamed:[NSString stringWithFormat:#"monk2.png"]];
CGFloat oImageWidth = originalImage.size.width;
CGFloat oImageHeight = originalImage.size.height;
// Draw the original image at the origin
CGRect oRect = CGRectMake(0, 0, oImageWidth, oImageHeight);
[originalImage drawInRect:oRect];
// Set the newRect to half the size of the original image
CGRect newRect = CGRectMake(0, 0, oImageWidth/2, oImageHeight/2);
UIImage *newImage = [self circularScaleNCrop:originalImage :newRect];
CGFloat nImageWidth = newImage.size.width;
CGFloat nImageHeight = newImage.size.height;
//Draw the scaled and cropped image
CGRect thisRect = CGRectMake(oImageWidth+10, 0, nImageWidth, nImageHeight);
[newImage drawInRect:thisRect];
}
Here is a quick way to create rounded corners on a square ImageView to make it look like a perfect circle. Basically you apply a corner radius equal to 1/2 the width (width == height on a square image).
#import <QuartzCore/QuartzCore.h> //you need QuartzCore
...
float width = imageView.bounds.size.width; // we can also use the frame property instead of bounds since we just care about the Size and don't care about position
imageView.layer.cornerRadius = width/2;
{
imageView.layer.cornerRadius = imageView.frame.size.height /2;
imageView.layer.masksToBounds = YES;
imageView.layer.borderWidth = 0;
}
UIImage category to mask an image with a circle:
UIImage *originalImage = [UIImage imageNamed:#"myimage.png"];
UImage *myRoundedImage = [UIImage roundedImageWithImage:originalImage];
Get it here.
I have another solution:
- (UIImage *)roundedImageWithRect:(CGRect)rect radius:(CGFloat)radius
{
UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0);
UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, rect.size.width, rect.size.height) cornerRadius:radius];
CGFloat imageRatio = self.size.width / self.size.height;
CGSize imageSize = CGSizeMake(rect.size.height * imageRatio, rect.size.height);
CGRect imageRect = CGRectMake(0, 0, imageSize.width, imageSize.height);
[path addClip];
[self drawInRect:imageRect];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
This variant is better for performance than set cornerRadius directly.
Personally, I'd create a transparent circle image with opaque corners to overlay the photo. This solution is only suitable where you will be placing the image in one place on the UI, and assumes the opaque corners will blend in with the background.
Following is the answer I given in How to crop UIImage on oval shape or circle shape? to make the image circle. It works for me..
Download the Support archive file
#import "UIImage+RoundedCorner.h"
#import "UIImage+Resize.h"
Following lines used to resize the image and convert in to round with radius
UIImage *mask = [UIImage imageNamed:#"mask.jpg"];
mask = [mask resizedImage:CGSizeMake(47, 47) interpolationQuality:kCGInterpolationHigh ];
mask = [mask roundedCornerImage:23.5 borderSize:1];
Just use
_profilePictureImgView.layer.cornerRadius = 32.0f;
_profilePictureImgView.layer.masksToBounds = YES;
The rounded corner has white background.
I followed other SO answers but don't know why i'm getting this whites
Bellow is the code.
UIView* testView = [[[UIView alloc] initWithFrame: self.animationView.bounds] autorelease];
UIImageView* testImageView = [[[UIImageView alloc] initWithImage:backImage] autorelease];
[testView addSubview: testImageView];
testImageView.backgroundColor = [UIColor clearColor];
CALayer* layer = [testView layer];
bool prev = layer.masksToBounds;
layer.masksToBounds = YES;
layer.cornerRadius = 30;
testView.clipsToBounds = YES;
UIImage* image = [UIImage captureView: testView];
//this image has the white regions in the four corners.
// when seen on iphone photo album
+ (UIImage*)captureView:(UIView*)view
{
CGSize size = view.bounds.size;
CGContextRef context = CreateARGBBitmapContext(size);
CGContextTranslateCTM(context, 0, size.height);
CGContextScaleCTM(context, 1.0, -1.0);
[view.layer renderInContext: context];
CGImageRef imageRef = CGBitmapContextCreateImage(context);
UIImage* img = [UIImage imageWithCGImage: imageRef];
CGImageRelease(imageRef);
CGContextRelease(context);
return img;
}
Add [testImageView setClipsToBounds:YES].
It might be that you have to set testImageView.opaque = NO.
I want to add outline on an image, do you have any idea?
Note: I don't need the border of imageview, not imageview.layer.borderColor nor image.layer.borderWidth;
Try this :
- (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;
}
source : http://www.icodesnip.com/snippet/objective-c/add-image-border-to-uiimage
This may not be a very clean way but may work and is simple.
//Make a UIView instance with required coords and size
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(...)];
//Set a backgroundColor, that will be the color of your border
view.backgroundColor = [UIColor ...];
// Make a UIImageView instance with the frame just leaving enough
// space around for the border.
UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(...)];
imageView.image = yourImage;
// Add the imageView to the view.
[view addSubview:imageView];
[imageView release];
// Release view accordingly after adding to some other view.
The sizes of the view and imageView will what give your image a border.
eg. (0, 0, 10, 10) -> view frame
(1, 1, 8, 8) -> imageView frame
This will give border of "1" to the image.
I have an image formed by a number of sublayers on a UIView, and then it takes a screenshot as so:
UIGraphicsBeginImageContext(object.bounds.size);
[object.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *screenShot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Then it puts it onto a button:
[objectButton setImage:screenShot forState:UIControlStateNormal];
But the image displays at it's own size, so if the button isn't the same size as the image then i have a problem of it not making the image bigger or smaller.
How can i get it to change the size of the image to the size of the button?
Try this category -
.h file -
#interface UIImage (UIImageAdditions)
- (UIImage*)scaleToSize:(CGSize)size;
#end
.m file -
#implementation UIImage (UIImageAdditions)
- (UIImage*)scaleToSize:(CGSize)size {
UIGraphicsBeginImageContext(size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(context, 0.0, size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, size.width, size.height), self.CGImage);
UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return scaledImage;
}
#end
you can call it like this -
[imageObject scaleToSize:CGSizeMake(weight, height)];
Hope it help!
Try Like this,
[objectButton setBackgroundImage:screenShot forState:UIControlStateNormal];
You can change the contentMode on the UIButton to scale to fit. This will adjust the size of the image to not be larger than the bounds of the button. Also set the image as the background Image of the button instead of the image.
objectButton.contentMode = UIViewContentModeScaleAspectFit;
[objectButton setBackgroundImage:image forStage:UIControlStateNormal];