I want to crop a 200*200 image, the cropped part is (x=10,y=10,w=50,h=50). and drawing this part to new 500*500 image, the new rect is (x=30,y=30,w=50, h=50), how to do it?
I can get the part of image with the following method
- (UIImage*) getSubImageWithRect: (CGRect) rect {
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
// translated rectangle for drawing sub image
CGRect drawRect = CGRectMake(-rect.origin.x, -rect.origin.y, self.size.width, self.size.height);
// clip to the bounds of the image context
// not strictly necessary as it will get clipped anyway?
CGContextClipToRect(context, CGRectMake(0, 0, rect.size.width, rect.size.height));
// draw image
[self drawInRect:drawRect];
// grab image
UIImage* subImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return subImage;
}
Lets try using following code chunk
- (UIImage*) getSubImageFromImage:(UIImage *)image
{
// translated rectangle for drawing sub image
CGRect drawRect = CGRectMake(10, 10, 50, 50);
// Create Image Ref on Image
CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], rect);
// Get Cropped Image
UIImage *img = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
return img;
}
Related
I'm currently coloring an existing image using a mask. For example, I have a white image with a black border and a circular mask (like the first two images). Then, I can create a third image with a color (i.e. green) which has green on the center of the original image (because the mask is present there).
The code I'm using is this (suggestions welcomed):
-(UIImage *)paintWithMask:(UIImage *)mask color:(UIColor *)color andSize:(CGSize)size{
UIImage *image = self;
UIImage *rotatedMask = [self rotateImage:mask]; //For some reason this is needed.
UIGraphicsBeginImageContextWithOptions(size, NO, image.scale);
CGRect rect = CGRectMake(0.0f, 0.0f, size.width, size.height);
[image drawInRect:rect];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetBlendMode(context, kCGBlendModeSourceIn);
CGContextSetFillColorWithColor(context, color.CGColor);
CGContextClipToMask(context, rect, [rotatedMask CGImage]);
CGContextFillRect(context, rect);
UIImage *coloredImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return coloredImage;
}
What I need to do now is paint the green circle using only the mask (without the black border obviously), like this:
Any ideas? Thanks a lot!!
There is a much easier way of doing this without CoreGraphics. Simply do the following:
-(UIImageView *)imageViewWithMask:(UIImage *)mask color:(UIColor *)color andSize:(CGSize)size{
UIImage *tempImage = mask;
tempImage = [tempImage imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
UIGraphicsBeginImageContextWithOptions(size, NO,0);
[tempImage drawInRect: CGRectMake(0,0,size.width,size.height)];
tempImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageView *iv = [[UIImageView alloc] initWithImage: tempImage];
iv.tintColor = color;
return iv;
}
In my app I have a scrollview with an added subview called allView.
In the scrollview delegate methods I am applying value of the current transformation of the scrollview's subview to another view called paint view
paintView.transform = allView.transform
and save it to the disk.
The image that is created in result of that process looks different than the one on the screen. Why? How can I fix it?
View Controller
- (void)scrollViewDidScroll:(UIScrollView *)scrollView; {
self.paintView.transform =self.allView.transform;
[self.paintView setNeedsDisplay];
}
- (void)scrollViewDidZoom:(UIScrollView *)scrollView{
self.backgroundView.transform = self.allView.transform;
[self.paintView setNeedsDisplay];
}
Paint View
Inside the PaintView's draw rect I am trying to apply transformation from the scroll view and
- (void)drawRect:(CGRect)rect
{
// Drawing code
// Draw on the screen
CGContextRef ctx1 =UIGraphicsGetCurrentContext();
CGContextConcatCTM(ctx1, self.transform);
CGColorRef wh = [[UIColor redColor]CGColor];
CGContextSetStrokeColorWithColor(ctx1, wh);
CGContextMoveToPoint(ctx1, 0, 0);
CGContextAddLineToPoint(ctx1, 200, 200);
CGContextStrokePath(ctx1);
// Apply scroll view's transformation
CGRect r = CGRectApplyAffineTransform(rect,self.transform );
//that gives a resized image
UIGraphicsBeginImageContextWithOptions(r.size, NO, 0.0);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextConcatCTM(ctx, self.transform);
// stroke and so on
CGContextSetStrokeColorWithColor(ctx, wh);
CGContextMoveToPoint(ctx, 0, 0);
CGContextAddLineToPoint(ctx, 200, 200);
CGContextStrokePath(ctx);
Getting image with entire content.
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
//Clipping the image
CGImageRef cgImg = CGImageCreateWithImageInRect(image.CGImage, rect);
UIImage *img = [UIImage imageWithCGImage:cgImg];
NSData * d = UIImageJPEGRepresentation(img, 0.8);
//saving the image (for debugging)
[self save:d];
UIGraphicsEndImageContext();
}
iOS Simulator
Image saved to the disk
It may be a little bit hard to diagnose the problem here without being able to have running code. However, I think the problem may be on these lines where you are clipping the image:
// Clipping the image
CGImageRef cgImg = CGImageCreateWithImageInRect(image.CGImage, rect);
UIImage *img = [UIImage imageWithCGImage:cgImg];
I think you actually just want to get the scroll view's visible rect, which would be scrollView.frame rather than the subview that fills the scroll view's entire contentSize. So, using some way (such as a property on paintView such as a visibleFrame), I would revise the lines to be something like this:
// Clipping the image
CGImageRef cgImg = CGImageCreateWithImageInRect(image.CGImage, self.visibleFrame);
UIImage *img = [UIImage imageWithCGImage:cgImg];
Hope this helps you get passed this issue!
I am trying to generate screenshot of UIView which having subview with CATransform3DMakeRotation. Screenshot is generated but it doesn't contain Rotation.
Is it possible to achieve this?
Actual View:
ScreenShot Image
Using following call to Flip the view horizontally...
currentView.layer.transform = CATransform3DConcat(currentView.layer.transform,CATransform3DMakeRotation(M_PI, 0.0, 1.0, 0.0f));
Code for taking screen shot
+ (UIImage *) imageWithView:(UIView *)view
{
CGSize screenDimensions = view.bounds.size;
// Create a graphics context with the target size
// (last parameter takes scale into account)
UIGraphicsBeginImageContextWithOptions(screenDimensions, NO, 0);
// Render the view to a new context
CGContextRef context = UIGraphicsGetCurrentContext();
[view.layer renderInContext:context];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
The "renderInContext" only works for Affine transform. So convert the 3D transform into affine transform like this
currentView.layer.affineTransform = CATransform3DGetAffineTransform(CATransform3DConcat(currentView.layer.transform,CATransform3DMakeRotation(M_PI, 0.0, 1.0, 0.0f)));
Try this code
CGSize newSize = CGSizeMake(yourview.frame.size.width , yourview.frame.size.height);
UIGraphicsBeginImageContextWithOptions(newSize,YES,2.0f);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
[yourview.layer renderInContext:context];
[yourview drawRect:yourview.frame];
UIImage *screenShot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
This might work, try it:
CGRect grabRect = CGRectMake(40,40,300,200);
//for retina displays
if ([[UIScreen mainScreen] respondsToSelector:#selector(scale)]) {
UIGraphicsBeginImageContextWithOptions(grabRect.size, NO, [UIScreen mainScreen].scale);
} else {
UIGraphicsBeginImageContext(grabRect.size);
}
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(ctx, -grabRect.origin.x, -grabRect.origin.y);
[self.view.layer renderInContext:ctx];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil);
i have achieved this in one of my application by doing a little tweak like first i capture the whole screen's screen shot and then crop it with the desired frame i need here is a sample code from my app.
- (UIImage *) croppedPhoto
{
[imgcropRectangle setHidden:TRUE];
UIGraphicsBeginImageContext(self.view.frame.size);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// Create bitmap image from original image data,
// using rectangle to specify desired crop area
CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], self.imgcropRectangle.frame);
UIImage *result = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
[imgcropRectangle setHidden:FALSE];
return result;
}
here imgcropRectangle is the UIImageView's object that defines my desired rectangle so i use it's frame for cropping from full screen to desired output. Hope it will help you :)
Try rendering view.layer.presentationLayer instead of view.layer
use this and before passing the view check its subviews :
+ (UIImage *) imageWithView:(UIView *)view
{
UIGraphicsBeginImageContext(CGSizeMake(view.frame.size.width, view.frame.size.height));
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return viewImage
}
In my application I draw a rectangle on an image view with my finger. The rectangle is created by using the drawRect method and added on that image view.
Now my issue is that I have to store that image along with those rectangles in photolibrary. Like an image with rectangles having on imageview.
Can anyone help me in finding how to do this?
Here is my code for drawRect method:
-(void)drawRect:(CGRect)rect
{
CGContextRef contextRef = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(contextRef, 5.0);
CGContextSetRGBStrokeColor(contextRef, 255.0, 1.0, 0.0, 1.0);
CGContextSetStrokeColorWithColor(contextRef,[UIColor redColor].CGColor);
// Draw the border along the view edge.
CGContextStrokeRect(contextRef, rect);
}
The method parameter view is the view on which both image and drawing are added. Calling this method will return an UIImage.
-(UIImage*)convertViewToImage:(UIView*)view
{
UIGraphicsBeginImageContext(view.bounds.size);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGImageRef imageRef = CGImageCreateWithImageInRect([viewImage CGImage], CGRectMake(0, 0, view.frame.size.width, view.frame.size.height));
UIImage *targetImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
return targetImage;
}
I'm trying to generate an image that is lozenge-shaped and shows some percentage finished versus unfinished. The way I implemented this was as follows:
Generate 2 rectangles - one the size of the filled region, the other the size of the empty rectange
Invoke UIGrapicsBeginImageContext() with the size of the rectangle I am interested in
Draw the 2 rectangles in the context side-by side
Grab the image from the context and end the context
Create a new masked image by using CGImageMaskCreate() followed by CGImageCreateWithMask() and extracting the masked image
I generate the filled and empty bitmaps using category extensions to UIImage, and then apply a static mask image to them.
The Problem: This works fine in the simulator, but the masking doesn't work on a real device.
Instead of including the code here, I'm including a link to a project that has the code. The relevant files are:
UIImage.h/UIImage.m: The category extension to UIImage that adds both the "create an image with a specified color" and "create a masked image using the supplied mask".
TLRangeDisplay.h/TLRangeDisplay.m: the code for my lozenge-shaped status display. The routine of interest there is fillWithRect().
Here is the code I added to UIImage (via a category):
+ (UIImage *)imageWithColor:(UIColor *)color {
CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [color CGColor]);
CGContextFillRect(context, rect);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
+ (UIImage *)imageWithColor:(UIColor *)color andSize:(CGSize)size {
CGRect rect = CGRectMake(0.0f, 0.0f, size.height, size.width);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [color CGColor]);
CGContextFillRect(context, rect);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
- (UIImage*) maskWith:(UIImage *)maskImage {
CGImageRef maskRef = maskImage.CGImage;
CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef), CGImageGetHeight(maskRef),
CGImageGetBitsPerComponent(maskRef),
CGImageGetBitsPerPixel(maskRef), CGImageGetBytesPerRow(maskRef), CGImageGetDataProvider(maskRef), NULL, false);
CGImageRef masked = CGImageCreateWithMask([self CGImage], mask);
UIImage* image = [UIImage imageWithCGImage:masked];
CFRelease(mask);
CFRelease(masked);
return image;
}
And here is the routine that does the masking:
-(void)fillWithRect {
CGRect f = self.frame;
CGFloat width = f.size.width;
CGFloat fullRange = maxValue_ - minValue_;
CGFloat filledRange = currentValue_ - minValue_;
CGRect fillRect = CGRectMake(0, 0, (filledRange * width) / fullRange, f.size.height);
CGRect emptyRect = CGRectMake(fillRect.size.width, 0, width - fillRect.size.width, f.size.height);
UIImage *fillImage = nil;
UIImage *emptyImage = nil;
if(fillRect.size.width > 0) {
fillImage = [UIImage imageWithColor:fillColor_ andSize:fillRect.size];
}
if(emptyRect.size.width > 0) {
emptyImage = [UIImage imageWithColor:emptyColor_ andSize:emptyRect.size];
}
// Build the 2-color image
UIGraphicsBeginImageContext(f.size);
[fillImage drawInRect:fillRect];
[emptyImage drawInRect:emptyRect];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// Mask it
if(nil != maskImage_)
image = [image maskWith:maskImage_];
CGRect fullRect = CGRectMake(0, 0, f.size.width, f.size.height);
// Merge ith with the shape
UIGraphicsBeginImageContext(f.size);
[image drawInRect:fullRect];
[shapeImage_ drawInRect:fullRect];
image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[shownView_ removeFromSuperview];
shownView_ = [[UIImageView alloc] initWithImage:image];
[self addSubview:shownView_];
if(nil != shownView_)
[self bringSubviewToFront:shownView_];
}
The project can be downloaded from http://dl.dropbox.com/u/5375467/ColorPlayOS4.zip
Thanks for any insights on this problem!