After trying the answer posted here the image that gets returned is of a very poor quality on the retina display. My mask image has a white background and black contents.
Output: https://dzwonsemrish7.cloudfront.net/items/22373o2Z260d3S051a05/Screenshot%202013.01.02%2000.04.57.png?v=34c4ab14
Code:
CGRect rect = CGRectMake(0.0f, 0.0f, 61.0f, 53.0f);
UIGraphicsBeginImageContextWithOptions(rect.size, NO, 2);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [UIColor blueColor].CGColor);
CGContextFillRect(context, rect);
UIImage *imageGradient = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImage *toggleImage = [UIImage imageNamed:#"RotationToggle.png"];
UIImage *inputImage = imageGradient;
CGImageRef maskRef = toggleImage.CGImage;
CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef),
CGImageGetHeight(maskRef),
CGImageGetBitsPerComponent(maskRef),
CGImageGetBitsPerPixel(maskRef),
CGImageGetBytesPerRow(maskRef),
CGImageGetDataProvider(maskRef), NULL, false);
CGImageRef masked = CGImageCreateWithMask(imageGradient.CGImage, mask);
CGImageRelease(mask);
UIImage *maskedImage = [UIImage imageWithCGImage:masked scale:inputImage.scale orientation:0];
CGImageRelease(masked);
I am not completely sure, but try changing this line:
UIImage *toggleImage = [UIImage imageNamed:#"RotationToggle.png"];
to this:
UIImage *toggleImage = [UIImage imageNamed:#"RotationToggle"];
or naive this:
UIImage *toggleImage = [UIImage imageNamed:#"RotationToggle#2x.png"];
The thing is: I think you force it to use low-quality image by assigning it this way. When skipping extension, Xcode will automatically look for Retina image and assign it if there exists one.
I may be wrong though, sorry if so.
Related
Hi i want to covert my UIView to UIImage in particular frame size kindly help me.
I have 'UITableView` which is added as subview of 'UIScrollView' for horizontal scroll, my table view frame size is (0, 0, 12000, 768).
I want to convert the current visible are of my UITableView as UIImage after scrolling.
Example:
if i scrolled my table view horizontally some distance means that current visible are is (150,0,1200,768) that means full device screen.
if i use the following code:
UIGraphicsBeginImageContext(self.frame.size);
[self.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *backgroundImage = UIGraphicsGetImageFromCurrentImageContext();
its capturing always the frame size of (0, 0, 1200, 768) only.
so, how can i set the origin of image capturing.
Kindly help me out.... Thanks in advance....
- (UIImage *)rasterizedImageInView:(UIView *)view atRect:(CGRect)rect {
UIGraphicsBeginImageContextWithOptions(rect.size, view.opaque, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(context, -rect.origin.x, -rect.origin.y);
[view.layer renderInContext:context];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
This will allow you to capture a UIImage from a particular region within a UIView as defined by a CGRect.
CGRect rect = [self.view bounds];
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[self.view.layer renderInContext:context];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Try this.
UIView *viewprint=[[UIView alloc] initWithFrame:CGRectMake(0, 0, width, height)];
viewprint.backgroundColor=[UIColor whiteColor];
tableView.frame = CGRectMake(0, 0, width, height);
[viewprint addSubview:tableView];
UIGraphicsBeginImageContext(viewprint.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[view.layer renderInContext:context];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
I have the self.view, but I only want to capture 300x320 of it.
got this code:
UIGraphicsBeginImageContext(self.view.bounds.size);
[self.view.window.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil);
UIImage * imgPrintScreen = [[UIImage alloc]init];
imgPrintScreen = viewImage;
What do I need to change here in order to do so?
Thanks allot!
Just change the size that you want to capture, instead of using the entire bounds, use the size you want. The render will start at the origin of the view and be clipped when it falls outside the bounds. If you need to change where the view is actually clipped, simply translate the context after starting the image context:
UIGraphicsBeginImageContextWithOptions(CGSizeMake(300, 320), YES, 0.);
[self.view.window.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
If your view was, for example, 600x320 and you wanted to capture the middle 300 points in width, you'd translate the context 150 points to the left:
UIGraphicsBeginImageContextWithOptions(CGSizeMake(300, 320), YES, 0.);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(context, -150.f, 0.f);
[self.view.window.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
I want to crop an image which is on the UIImageview into any shape
You set the clipping path and voila:
// Load image thumbnail
NSString *imageName = [self.picArray objectAtIndex:indexPath.row];
UIImage *image = [UIImage imageNamed:imageName];
CGSize imageSize = image.size;
CGRect imageRect = CGRectMake(0, 0, imageSize.width, imageSize.height);
UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);
// Create the clipping path and add it
UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:imageRect cornerRadius:5.0f];
[path addClip];
[image drawInRect:imageRect];
UIImage *roundedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
This code loads an image and creates a path by rounding the rectangle, the result is that the final image has been clipped, i.e. rounded corners. RoundedImage is the result.
You can use a CGImageMask.
A sample exists in the class QuartzMaskingView of Apple's QuartzDemo.
In mac osx (cocoa), It is very easy to make a blank image of a specific size and draw to it off screen:
NSImage* image = [[NSImage alloc] initWithSize:NSMakeSize(64,64)];
[image lockFocus];
/* drawing code here */
[image unlockFocus];
However, in iOS (cocoa touch) there does not seem to be equivalent calls for UIImage. I want to use UIImage (or some other equivalent class) to do the same thing. That is, I want to make an explicitly size, initially empty image to which I can draw using calls like UIRectFill(...) and [UIBezierPath stroke].
How would I do this?
CoreGraphics is needed here, as UIImage does not have high level functions like what you explained..
UIGraphicsBeginImageContext(CGSizeMake(64,64));
CGContextRef context = UIGraphicsGetCurrentContext();
// drawing code here (using context)
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
You can do that as follows:
UIGraphicsBeginImageContext(CGSizeMake(64, 64));
//Drawing code here
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Here is Apple's Graphics and Drawing reference.
Something like this:
UIGraphicsBeginImageContextWithOptions(mySize, NO, 0.0f);
CGContextRef context = UIGraphicsGetCurrentContext();
UIGraphicsPushContext(context);
[myImage drawInRect:myImageRect];
[myText drawAtPoint:myOrigin withFont:myFont];
UIGraphicsPopContext();
UIImage *myNewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
I'm trying to create an image mask that from a composite of two existing images.
First I start with creating the composite which consists of a small image that is the masking image, and a larger image which is the same size as the background:
UIImage *baseTextureImage = [UIImage imageNamed:#"background.png"];
UIImage *maskImage = [UIImage imageNamed:#"my_mask.jpg"];
UIImage *shapesBase = [UIImage imageNamed:#"largerimage.jpg"];
UIImage *maskImageFull;
CGSize finalSize = CGSizeMake(480.0, 320.0);
UIGraphicsBeginImageContext(finalSize);
[shapesBase drawInRect:CGRectMake(0, 0, 480, 320)];
[maskImage drawInRect:CGRectMake(150, 50, 250, 250)];
maskImageFull = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
I can output this UIImage (MaskImageFull) and it looks right. It is a full size background size and it has a white background with my mask object in black, in the right place on the screen.
I then pass the MaskImageFull UIImage through this:
CGImageRef maskRef = [maskImage CGImage];
CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef),
CGImageGetHeight(maskRef),
CGImageGetBitsPerComponent(maskRef),
CGImageGetBitsPerPixel(maskRef),
CGImageGetBytesPerRow(maskRef),
CGImageGetDataProvider(maskRef), NULL, false);
CGImageRef masked = CGImageCreateWithMask([image CGImage], mask);
UIImage *retImage= [UIImage imageWithCGImage:masked];
The problem is that the retImage is all black. If I send a pre-made UIImage in as the mask it works fine, it is just when I try to make it from multiple images that it breaks.
I thought it was a colorspace thing but couldn't seem to fix it. Any help is much appreciated!
I tried the same thing with CGImageCreateWithMask, and got the same result. The solution I found was to use CGContextClipToMask instead:
CGContextRef mainViewContentContext;
CGColorSpaceRef colorSpace;
colorSpace = CGColorSpaceCreateDeviceRGB();
// create a bitmap graphics context the size of the image
mainViewContentContext = CGBitmapContextCreate (NULL, targetSize.width, targetSize.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);
// free the rgb colorspace
CGColorSpaceRelease(colorSpace);
if (mainViewContentContext==NULL)
return NULL;
CGImageRef maskImage = [[UIImage imageNamed:#"mask.png"] CGImage];
CGContextClipToMask(mainViewContentContext, CGRectMake(0, 0, targetSize.width, targetSize.height), maskImage);
CGContextDrawImage(mainViewContentContext, CGRectMake(thumbnailPoint.x, thumbnailPoint.y, scaledWidth, scaledHeight), self.CGImage);
// Create CGImageRef of the main view bitmap content, and then
// release that bitmap context
CGImageRef mainViewContentBitmapContext = CGBitmapContextCreateImage(mainViewContentContext);
CGContextRelease(mainViewContentContext);
// convert the finished resized image to a UIImage
UIImage *theImage = [UIImage imageWithCGImage:mainViewContentBitmapContext];
// image is retained by the property setting above, so we can
// release the original
CGImageRelease(mainViewContentBitmapContext);
// return the image
return theImage;
- (UIImage *) maskImage:(UIImage *)image {
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
UIImage *maskImage = [UIImage imageNamed:#"MaskFinal.png"];
CGImageRef maskImageRef = [maskImage CGImage];
// create a bitmap graphics context the size of the image
CGContextRef mainViewContentContext = CGBitmapContextCreate (NULL, maskImage.size.width, maskImage.size.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);
if (mainViewContentContext==NULL)
return NULL;
CGFloat ratio = 0;
ratio = maskImage.size.width/ image.size.width;
if(ratio * image.size.height < maskImage.size.height) {
ratio = maskImage.size.height/ image.size.height;
}
CGRect rect1 = {{0, 0}, {maskImage.size.width, maskImage.size.height}};
CGRect rect2 = {{-((image.size.width*ratio)-maskImage.size.width)/2 , -((image.size.height*ratio)-maskImage.size.height)/2}, {image.size.width*ratio, image.size.height*ratio}};
CGContextClipToMask(mainViewContentContext, rect1, maskImageRef);
CGContextDrawImage(mainViewContentContext, rect2, image.CGImage);
// Create CGImageRef of the main view bitmap content, and then
// release that bitmap context
CGImageRef newImage = CGBitmapContextCreateImage(mainViewContentContext);
CGContextRelease(mainViewContentContext);
UIImage *theImage = [UIImage imageWithCGImage:newImage];
CGImageRelease(newImage);
// return the image
return theImage;
}
The image to be masked MUST be created with an alpha channel. The Alpha channel may not be created from the code.