I am getting into a dilemma. I am trying to show the middle of an image. I use the the mageWithImage:CovertToSize function to scale the image. The problem is that the image is being stretched height wise. So the question is, what is the correct method to scale an image to 320 pixels wide and show the middle of the photo or close to it?
UIImage *image = [[UIImage alloc] initWithData:imageData];
Scale *scale = [[Scale alloc] init];
float newHeight = (image.size.height * 2) / image.size.width * 320.0f;
image = [scale2 imageWithImage:image CovertToSize:CGRectMake(0, -(newHeight / 2), 320.0f, newHeight)];
CGImageRef imageRef;
if (newHeight > 125) {
imageRef = CGImageCreateWithImageInRect([image CGImage], CGRectMake(0, 0, 320, 125));
}else{
imageRef = CGImageCreateWithImageInRect([image CGImage], CGRectMake(0, 0, 320, newHeight));
}
NSData *imgData = UIImageJPEGRepresentation([UIImage imageWithCGImage:imageRef], 1.0);
UIImage *cimg = [UIImage imageWithData:imgData];
If your not aware of how layers work, http://www.ruttencutter.com/?p=90
If you are, I suggest you have a frame of an image as a layer with the selected area in the middle cut out so that, under that layer, you can put the image there so that you'll only see that selected area.
Related
In objective-c, I make a circle shape programmatically by following codes:
+(UIImage *)makeRoundedImage:(CGSize) size backgroundColor:(UIColor *) backgroundColor cornerRadius:(int) cornerRadius
{
UIImage* bgImage = [self imageWithColor:backgroundColor andSize:size];;
CALayer *imageLayer = [CALayer layer];
imageLayer.frame = CGRectMake(0, 0, size.width, size.height);
imageLayer.contents = (id) bgImage.CGImage;
imageLayer.masksToBounds = YES;
imageLayer.cornerRadius = cornerRadius;
UIGraphicsBeginImageContext(bgImage.size);
[imageLayer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *roundedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return roundedImage;
}
The imageWithColor method is as following:
+(UIImage *)imageWithColor:(UIColor *)color andSize:(CGSize)size
{
//quick fix, or pop up CG invalid context 0x0 bug
if(size.width == 0) size.width = 1;
if(size.height == 0) size.height = 1;
//---quick fix
UIImage *img = nil;
CGRect rect = CGRectMake(0, 0, size.width, size.height);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context,
color.CGColor);
CGContextFillRect(context, rect);
img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
Then I used it to create a pure color circle shape image, but what I found is the circle image is not perfect rounded. As an example, please see following code:
CGSize size = CGSizeMake(diameter, diameter);
int r = ceil((float)diameter/2.0);
UIImage *imageNormal = [self makeRoundedImage:size backgroundColor:backgroundColor cornerRadius:r];
[slider setThumbImage:imageNormal forState:UIControlStateNormal];
First I created a circle image, then I set the image as the thumb to a UISlider. But what shown is as the picture shown below:
You can see the circle is not an exact circle. I'm thinking probably it caused by the screen resolution issue? Because if I use an image resource for the thumb, I need add #2x. Anybody know the reason? Thanx in advance.
updated on 8th Aug 2015.
Further to this question and the answer from #Noah Witherspoon, I found the blurry edge issue has been solved. But still, the circle looks like being cut. I used the code as following:
CGRect rect = CGRectMake(0.0f, 0.0f, radius*2.0f, radius*2.0f);
UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, color.CGColor);
CGContextFillEllipseInRect(context, rect);
UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
And the circle looks like:
You can see the edge has been cut.
I changed the code as following:
CGRect rect = CGRectMake(0.0f, 0.0f, radius*2.0f+4, radius*2.0f+4);
CGRect rectmin = CGRectMake(2.0f, 2.0f, radius*2, radius*2);
UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, color.CGColor);
CGContextFillEllipseInRect(context, rectmin);
UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
You can see the circle looks better(The top edge and the bottom edge):
I made the fill rect size smaller, and the edge looks better, but I don't think it's a nice solution. Still, does anybody know why this happen?
From your screenshot it looks like you do actually have a circular image, but its scale is wrong—it’s not Retina—so it looks blurry and not-circular. The key thing is that instead of using UIGraphicsBeginImageContext which defaults to a scale of 1.0 (as compared to your screen, which is at a scale of 2.0 or 3.0), you should be using UIGraphicsBeginImageContextWithOptions. Also, you don’t need to make a layer or a view to draw a circle in an image context.
+ (UIImage *)makeCircleImageWithDiameter:(CGFloat)diameter color:(UIColor *)color {
UIGraphicsBeginImageContextWithOptions(CGSizeMake(diameter, diameter), NO, 0 /* scale (0 means “use the current screen’s scale”) */);
[color setFill];
CGContextFillEllipseInRect(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, diameter, diameter));
UIImage *image = UIGraphicsGetImageFromCurrentContext();
UIGraphicsEndImageContext();
return image;
}
If you want to get a circle every time try this:
- (UIImage *)makeCircularImage:(CGSize)size backgroundColor:(UIColor *)backgroundColor {
CGSize squareSize = CGSizeMake((size.width > size.height) ? size.width : size.height,
(size.width > size.height) ? size.width : size.height);
UIView *circleView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, squareSize.width, squareSize.height)];
circleView.layer.cornerRadius = circleView.frame.size.height * 0.5f;
circleView.backgroundColor = backgroundColor;
circleView.opaque = NO;
UIGraphicsBeginImageContextWithOptions(circleView.bounds.size, circleView.opaque, 0.0);
[circleView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
How can i show only a portion of the original image in a UIImageView
This question may be very familiar and old, But the reason for asking again is,i could not find a workable idea with the help of those answers
Many said set image.contentMode = UIViewContentModeCenter; (but not working)
I need almost a rectangle containing the center of the original image,How do I get this ?
I do make this working,when i am displaying a static image to my app and setting Content mode of UIImageVie as Aspect Fill.
But this is not workable in the case when i am displaying an image from url and using NSData
Adding my code and the images
NSString *weburl = #"http://topnews.in/files/Sachin-Tendulkar_15.jpg";
UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(10, 50, 108, 86)];
NSURL *url = [NSURL URLWithString:weburl];
NSData *data = [NSData dataWithContentsOfURL:url];
imageView.image = [UIImage imageWithData:data];
[self.view addSubview:imageView];
If you added the UIImageView form XIB, you can find a "mode" property there and then you can see and set different modes from there (from Interface builder). Or by programatically, you can set different modes by
imageView.contentMode = UIViewContentModeCenter;
imageView.clipsToBounds = YES;
Try this:
self.imageView.layer.contentsRect = CGRectMake(0.25, 0.25, 0.5, 0.5);
self.imageView will display middle part of image. You can calculate itself the required values of CGRect
For this kind of output, you need to crop the image according to your requirement.
Cropping code as below which can be used.
-(UIImage *) CropImageFromTop:(UIImage *)image
{
CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], CGRectMake(0, 12, image.size.width, image.size.height - 12));
UIImage *cropimage = [[[UIImage alloc] initWithCGImage:imageRef] autorelease];
CGImageRelease(imageRef);
return cropimage;
}
you try to scale image and then add image in UiImageView and set center that image then it is in center. code of scale image is
-(UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize{
UIGraphicsBeginImageContext(newSize);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
then you set the center of that image and add in the image view i hope this is work
I'm rendering UIImage in the - drawRect: and placing it in the passed in CGRect by calling drawInRect: rect on the UIImage. It automatically resizes and stretches itself, which I don't want. How can I keep it the original size?
UIImage* left = [UIImage imageNamed: #"Map_info_bubble_left"];
UIImage* center = [UIImage imageNamed: #"Map_info_bubble_center"];
UIImage* right = [UIImage imageNamed: #"Map_info_bubble_right"];
UIImage* leftCapStretched = [left resizableImageWithCapInsets: UIEdgeInsetsMake(0, 20, 0, 0)];
UIImage* rightCapStretched = [right resizableImageWithCapInsets: UIEdgeInsetsMake(0, 0, 0, 15)];
CGFloat fullWidth = leftCapStretched.size.width + center.size.width + rightCapStretched.size.width;
UIGraphicsBeginImageContextWithOptions(CGSizeMake(fullWidth, center.size.height), NO, 0);
[leftCapStretched drawAtPoint: CGPointMake(0, 0)];
[center drawAtPoint: CGPointMake(leftCapStretched.size.width, 0)];
[rightCapStretched drawAtPoint: CGPointMake(left.size.width + center.size.width, 0)];
UIImage* callout = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[callout drawInRect: rect];
Essentially what is happening is the center image should remain the original size while the caps stretch, but the center is stretching and the caps don't stretch enough. I noticed that if I multiply fullWidth by 2, it shrinks the center closer to what it should be.
EDIT: More simply asked after reading the documentation a bit more, is there a way to prevent the UIImage from scaling to fit the rect when drawInRect: is called?
This can be done simply by passing the images size property to drawInRect:
e.x:
[myImage drawInRect:CGRectMake(someOriginX, someOriginY, myImage.size.width, myImage.size.height)];
I'm facing the following problem : I have to merge two images A and B to create a new image C as a result of the merging.
I already know how to merge two images but in this case my goal is a little bit different.
I would like that image A will be the background for Image B.
For instance if image A size is 500x500 and image B size is 460x460 I would like that image C (the image result of the merging) will be 500x500, with image B (460x460) centered in it.
Thanks in advance for any help or suggestion
This is what I've done in my app, but without using UIImageView:
UIImage *bottomImage = [UIImage imageNamed:#"bottom.png"]; //background image
UIImage *image = [UIImage imageNamed:#"top.png"]; //foreground image
CGSize newSize = CGSizeMake(width, height);
UIGraphicsBeginImageContext( newSize );
// Use existing opacity as is
[bottomImage drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
// Apply supplied opacity if applicable
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height) blendMode:kCGBlendModeNormal alpha:0.8];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
If the image already has opacity, you do not need to set it (as in bottomImage) otherwise you can set it (as with image).
After this UIImage is created then you can embed it in your UIImageView
UPDATE: Thanks to Ahmet AkkoK - for Swift (2.2) users blend mode macro has changed. CGBlendMode .kCGBlendModeNormal is replaced with CGBlendMode.Normal
Hey i got multiple images add same background with different foreground
This is my code
UIImage *bottomImage = [UIImage imageNamed:#"photo 2.JPG"]; //background image
UIImage *image = [UIImage imageNamed:#"photo 3.JPG"]; //foreground image
UIImage *image1 = [UIImage imageNamed:#"photo 4.JPG"]; //foreground image
UIImage *image2 = [UIImage imageNamed:#"photo 5.JPG"]; //foreground image
CGSize newSize = CGSizeMake(320, 480);
UIGraphicsBeginImageContext( newSize );
// Use existing opacity as is
[bottomImage drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
// Apply supplied opacity if applicable
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height) blendMode:kCGBlendModeNormal alpha:0.4];
[image1 drawInRect:CGRectMake(0,0,newSize.width,newSize.height) blendMode:kCGBlendModeNormal alpha:0.3];
[image2 drawInRect:CGRectMake(0,0,newSize.width,newSize.height) blendMode:kCGBlendModeNormal alpha:0.2];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
resultView = [[UIImageView alloc] initWithImage:newImage];
resultView.frame = CGRectMake(0, 0,320,460);
[self.view addSubview:resultView];
Swift version
Copy/Paste to Playground
var bottomImage:UIImage = UIImage(named:"avatar_4.png") //background image
var imageTop:UIImage = UIImage(named:"group_4.png") //top image
var newSize = CGSizeMake(bottomImage.size.width, bottomImage.size.height)
UIGraphicsBeginImageContext( newSize )
bottomImage.drawInRect(CGRectMake(0,0,newSize.width,newSize.height))
// decrease top image to 36x36
imageTop.drawInRect(CGRectMake(18,18,36,36), blendMode:kCGBlendModeNormal, alpha:1.0)
var newImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()
var imageData = UIImagePNGRepresentation(newImage)
To load images from playground:
Open playground file and create there folder Resources
copy images to this folder
Just made quick paste function for those of you who wanted to use Srikar Appal answer. (if in case background & foreground images are of different sizes)
- (UIImage *) mergeImages:(NSString *)bgImageFileName foreGround:(NSString *)fgImageFileName {
UIImage *bottomImage = [UIImage imageNamed:bgImageFileName]; //background image
UIImage *image = [UIImage imageNamed:fgImageFileName]; //foreground image
CGSize newSize = CGSizeMake(bottomImage.size.width, bottomImage.size.height);
UIGraphicsBeginImageContext(newSize);
// Use existing opacity as is
[bottomImage drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
// Apply supplied opacity if applicable
// Change xPos, yPos if applicable
[image drawInRect:CGRectMake(11,11,image.size.width,image.size.height) blendMode:kCGBlendModeNormal alpha:1.0];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
in Swift:
let bottomImage = UIImage(named: "Bottom_Image.png")
let frontImage = UIImage (named: "Front_Image.png")
let size = CGSize(width: 67, height: 55)
UIGraphicsBeginImageContext(size)
let areaSize = CGRect(x: 0, y: 0, width: size.width, height: size.height)
let frontImageSize = CGRect(x: 14, y: 3, width: 40, height: 40)
bottomImage!.drawInRect(areaSize, blendMode: CGBlendMode.Normal, alpha: 1.0)
frontImage!.drawInRect(frontImageSize, blendMode: CGBlendMode.Normal, alpha: 1.0)
let newImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
Thanks #Srikar Appal for iOS soultion.
For anyone who is looking for merge in OS X:
- (NSImage *) mergeImages:(NSString *)bgImageFileName foreGround:(NSString *)fgImageFileName {
NSImage *bottomImage = [NSImage imageNamed:bgImageFileName];
NSImage *overlayedImage = [NSImage imageNamed:fgImageFileName];
NSSize newSize = NSMakeSize(bottomImage.size.width, bottomImage.size.height);
NSSize overlaySize = NSMakeSize(newSize.width/2, newSize.height/2); //change the size according to your requirements
NSImage *newImage = [[NSImage alloc] initWithSize:newSize];
[newImage lockFocus];
[bottomImage drawInRect:NSMakeRect(0, 0, newSize.width, newSize.height)];
[overlayedImage drawInRect:NSMakeRect(newSize.width-overlaySize.width, 0, overlaySize.width, overlaySize.height)]; //set the position as required
[newImage unlockFocus];
return newImage;
}
You can go with another trick as described below:
Add first image to a imageView.
Add second image to another imageView.
Add both the above imageViews in a single main imageView and access the combined image by property of imageView : mainImageView.image
Have a look at the code below :
CGRect rect= investmentDetailTblView.frame;
int rows = investmentDetailArray.count;
CGFloat heightFinal = 5;
CGRect frame1;
for (int i=0; i<rows; i++)
{
frame1 = [investmentDetailTblView rectForRowAtIndexPath:[NSIndexPath indexPathForRow:i inSection:0]];
CGFloat height = frame1.size.height;
heightFinal = heightFinal + height;
}
rect.size.height = heightFinal;
investmentDetailTblView.frame=rect;
UIImageView *imageViewTable = [[UIImageView alloc] init];
[imageViewTable setFrame:CGRectMake(0, 0, frame1.size.width, heightFinal)];
[investmentDetailTblView reloadData];
if ([[UIScreen mainScreen] respondsToSelector:#selector(scale)])
UIGraphicsBeginImageContextWithOptions(investmentDetailTblView.bounds.size, NO, [UIScreen mainScreen].scale);
else
UIGraphicsBeginImageContext(investmentDetailTblView.bounds.size);
[investmentDetailTblView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
imageViewTable.image = image; //Adding the table image to the image view.
CGRect frame=CGRectMake(0, heightFinal+5, investmentDetailTblView.frame.size.width, 20) ;
UIView *footerView=[DataStore kkrLogoView];
footerView.frame=frame;
if ([[UIScreen mainScreen] respondsToSelector:#selector(scale)])
UIGraphicsBeginImageContextWithOptions(footerView.frame.size, NO, [UIScreen mainScreen].scale);
else
UIGraphicsBeginImageContext(footerView.frame.size);
[footerView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *kkrLogoImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageView *imageViewFooter = [[UIImageView alloc] init];
[imageViewFooter setFrame:CGRectMake(0, heightFinal, footerView.frame.size.width, footerView.frame.size.height)];
imageViewFooter.image = kkrLogoImage; //Adding the footer image to the image view.
UIImageView *mainImageView = [[UIImageView alloc] init];
[mainImageView setFrame:CGRectMake(0, 0, frame1.size.width, (heightFinal+footerView.frame.size.height))];
[mainImageView addSubview:imageViewTable];
[mainImageView addSubview:imageViewFooter];
if ([[UIScreen mainScreen] respondsToSelector:#selector(scale)])
UIGraphicsBeginImageContextWithOptions(mainImageView.frame.size, NO, [UIScreen mainScreen].scale);
else
UIGraphicsBeginImageContext(mainImageView.frame.size);
[mainImageView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *finalImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
I am using QREncoder library found here: https://github.com/jverkoey/ObjQREncoder
Basically, i looked at the example code by this author, and when he creates the QRCode it comes out perfectly with no pixelation. The image itself that the library provides is 33 x 33 pixels, but he uses kCAFilterNearest to magnify and make it very clear (no pixilation). Here is his code:
UIImage* image = [QREncoder encode:#"http://www.google.com/"];
UIImageView* imageView = [[UIImageView alloc] initWithImage:image];
CGFloat qrSize = self.view.bounds.size.width - kPadding * 2;
imageView.frame = CGRectMake(kPadding, (self.view.bounds.size.height - qrSize) / 2,
qrSize, qrSize);
[imageView layer].magnificationFilter = kCAFilterNearest;
[self.view addSubview:imageView];
I have a UIImageView in a xib, and I am setting it's image like this:
[[template imageVQRCode] setImage:[QREncoder encode:ticketNum]];
[[[template imageVQRCode] layer] setMagnificationFilter:kCAFilterNearest];
but the qrcode is really blurry. In the example, it comes out crystal clear.
What am i doing wrong?
Thanks!
UPDATE:I found out that the problem isn't with scaling or anything to do with kCAFFilterNearest. It has to do with generating the PNG image from the view. Here's how it looks on the deive vs how it looks like when i save the UIView to the PNG representation (Notice the QRCodes quality):
UPDATE 2: This is how I am generating the PNG file from UIView:
UIGraphicsBeginImageContextWithOptions([[template view] bounds].size, YES, 0.0);
[[[template view] layer] renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[UIImagePNGRepresentation(viewImage) writeToFile:plistPath atomically:YES];
I have used below function for editing image.
- (UIImage *)resizedImage:(CGSize)newSize interpolationQuality:(CGInterpolationQuality)quality
{
BOOL drawTransposed;
switch (self.imageOrientation) {
case UIImageOrientationLeft:
case UIImageOrientationLeftMirrored:
case UIImageOrientationRight:
case UIImageOrientationRightMirrored:
drawTransposed = YES;
break;
default:
drawTransposed = NO;
}
return [self resizedImage:newSize
transform:[self transformForOrientation:newSize]
drawTransposed:drawTransposed
interpolationQuality:quality];
}
- (UIImage *)resizedImage:(CGSize)newSize
transform:(CGAffineTransform)transform
drawTransposed:(BOOL)transpose
interpolationQuality:(CGInterpolationQuality)quality
{
CGRect newRect = CGRectIntegral(CGRectMake(0, 0, newSize.width, newSize.height));
CGRect transposedRect = CGRectMake(0, 0, newRect.size.height, newRect.size.width);
CGImageRef imageRef = self.CGImage;
// Build a context that's the same dimensions as the new size
CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
if((bitmapInfo == kCGImageAlphaLast) || (bitmapInfo == kCGImageAlphaNone))
bitmapInfo = kCGImageAlphaNoneSkipLast;
CGContextRef bitmap = CGBitmapContextCreate(NULL,
newRect.size.width,
newRect.size.height,
CGImageGetBitsPerComponent(imageRef),
0,
CGImageGetColorSpace(imageRef),
bitmapInfo);
// Rotate and/or flip the image if required by its orientation
CGContextConcatCTM(bitmap, transform);
// Set the quality level to use when rescaling
CGContextSetInterpolationQuality(bitmap, quality);
// Draw into the context; this scales the image
CGContextDrawImage(bitmap, transpose ? transposedRect : newRect, imageRef);
// Get the resized image from the context and a UIImage
CGImageRef newImageRef = CGBitmapContextCreateImage(bitmap);
UIImage *newImage = [UIImage imageWithCGImage:newImageRef];
// Clean up
CGContextRelease(bitmap);
CGImageRelease(newImageRef);
return newImage;
}
UIImageWriteToSavedPhotosAlbum([image resizedImage:CGSizeMake(300, 300) interpolationQuality:kCGInterpolationNone], nil, nil, nil);
Please find below image and let me know if you need any help.