I am using this code to change the size of images.
- (UIImage *)scaledImage:(UIImage *)image size:(CGSize)size {
UIGraphicsBeginImageContextWithOptions(size, NO, 1.0);
[image drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
I am currently in need to change the size of 100 images at runtime but this code causes delay. The loading time is much.
Is there any faster way to resize the UIImage?
Thanks
try this code :
CGRect rect = CGRectMake(0,0,75,75);
UIGraphicsBeginImageContext( rect.size );
[yourCurrentOriginalImage drawInRect:rect];
UIImage *picture1 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSData *imageData = UIImagePNGRepresentation(picture1);
UIImage *img=[UIImage imageWithData:imageData];
'- (UIImage *)scaledImage:(UIImage *)image size:(CGSize)size {
CGRect rect = CGRectMake(0,0, size.width,size.height);
UIGraphicsBeginImageContext( size );
[image drawInRect:rect];
UIImage *picture1 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSData *imageData = UIImagePNGRepresentation(picture1);
UIImage *img=[UIImage imageWithData:imageData];
return img;
}'
Related
I want to scale down UIImage and use following method.
- (UIImage *)imageWithImage:(UIImage *)image convertToSize:(CGSize)size {
UIGraphicsBeginImageContext(size);
[image drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *destImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return destImage;
}
It returns correct dimensions but having larger image size(memory) than original image. How to optimize the method?
You can compress your image so its size will decrese
NSData* data = UIImageJPEGRepresentation(image, 0.8);
- (UIImage *)createThumbnailImage:(UIImage *)image withSize:(CGSize)size {
CGRect imageRect = CGRectMake(0.0, 0.0, size.width, size.height);
UIGraphicsBeginImageContext(size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextClearRect(context, CGRectMake(0, 0, size.width, size.height));
CGContextSetInterpolationQuality(context, 0.8);
[image drawInRect:imageRect blendMode:kCGBlendModeNormal alpha:1];
UIImage *thumbnail = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return thumbnail;
}
- (void)viewDidLoad {
[super viewDidLoad];
UIImage *inputImage = [UIImage imageNamed:#"dog.jpg"];
UIImage *image = [self createThumbnailImage:inputImage withSize:CGSizeMake(640.0, 480.0)]
}
I got a thumbnail image(640 * 480) by code above. And some odd problem confused me.
When I sent a jpg (10000 * 10000) to the method，it worked well.
But when I sent a png with the same size, the app would crash.
I tried to find some documents about the difference between jpg and png, but it made no sense.
Does anyone have any idea about this bug?
-(UIImage *)getNeedImageFrom:(UIImage*)image cropRect:(CGRect)rect
{
CGImageRef subImage = CGImageCreateWithImageInRect(image.CGImage, rect);
UIImage *croppedImage = [UIImage imageWithCGImage:subImage];
CGImageRelease(subImage);
return croppedImage;
}
can you please check if this solve your problem
Hi I am developing an iOS app. I have an UIImageView with a image associated with it. I am changing its dimensions in viewDidLoad() method.
Initially when I change the dimension I am able to resize the image size on view. However after I crop the image(using Photoshop) accordingly to the shape of the object in the image(i.e getting rid of unwanted part of the image). My resize method doesn't seem to work i.e the size of the image is not changing though I call the same method.
The method I am using for resizing is given below.
-(void)initXYZ{
CGSize size;
CGFloat x,y;
x = 0+myImageView1.frame.size.width;
y = myImageView2.center.y;
size.width = _myImageView2.frame.size.width/2;
size.height = _myImageView2.frame.size.width/2;
UIImage *image = [UIImage imageNamed:#"xyz.png"];
image = [HomeViewController imageWithImage:image scaledToSize:size xCord:x yCord:y];}
Utility method is given below
+(UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize xCord:(CGFloat)X yCord:(CGFloat)Y{
UIGraphicsBeginImageContextWithOptions(newSize,NO,0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;}
Try this...
+ (UIImage*)imageWithImage:(UIImage*)image
scaledToSize:(CGSize)newSize
{
UIGraphicsBeginImageContext( newSize );
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
OR
+ (UIImage*)imageWithImage:(UIImage*)image
scaledToSize:(CGSize)newSize {
CGRect newRect = CGRectIntegral(CGRectMake(0, 0, newSize.width, newSize.height));
CGImageRef imageRef = image.CGImage;
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
CGAffineTransform flipV = CGAffineTransformMake(1, 0, 0, -1, 0, newSize.height);
CGContextConcatCTM(context, flipV);
CGContextDrawImage(context, newRect, imageRef);
CGImageRef newImageRef = CGBitmapContextCreateImage(context);
UIImage *newImage = [UIImage imageWithCGImage:newImageRef];
CGImageRelease(newImageRef);
UIGraphicsEndImageContext();
return newImage;
}
Try this:
- (UIImage*)resizeAndStoreImages:(UIImage*)img
{
UIImage *chosenImage = img;
NSData *imageData = UIImageJPEGRepresentation(chosenImage, 1.0);
int resizedImgMaxHeight = 500;
int resizedImgMaxWidth = 500;
UIImage *resizedImageData;
if (chosenImage.size.height > chosenImage.size.width && chosenImage.size.height > resizedImgMaxHeight) { // portrait
int width = (chosenImage.size.width / chosenImage.size.height) * resizedImgMaxHeight;
CGRect rect = CGRectMake( 0, 0, width, resizedImgMaxHeight);
UIGraphicsBeginImageContext(rect.size);
[chosenImage drawInRect:rect];
UIImage *pic1 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
resizedImageData = [UIImage imageWithData:UIImageJPEGRepresentation(pic1, 1.0)];
pic1 = nil;
} else if (chosenImage.size.width > chosenImage.size.height && chosenImage.size.width > resizedImgMaxWidth) { // landscape
int height = (chosenImage.size.height / chosenImage.size.width) * resizedImgMaxWidth;
CGRect rect = CGRectMake( 0, 0, resizedImgMaxWidth, height);
UIGraphicsBeginImageContext(rect.size);
[chosenImage drawInRect:rect];
UIImage *pic1 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
resizedImageData = [UIImage imageWithData:UIImageJPEGRepresentation(pic1, 1.0)];
pic1 = nil;
} else {
if (chosenImage.size.height > resizedImgMaxHeight) {
int width = (chosenImage.size.width / chosenImage.size.height) * resizedImgMaxHeight;
CGRect rect = CGRectMake( 0, 0, width, resizedImgMaxHeight);
UIGraphicsBeginImageContext(rect.size);
[chosenImage drawInRect:rect];
UIImage *pic1 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
resizedImageData = [UIImage imageWithData:UIImageJPEGRepresentation(pic1, 1.0)];
pic1 = nil;
} else {
resizedImageData = [UIImage imageWithData:imageData];
}
}
return resizedImageData;
}
Adjust the resizedImgMaxHeight and resizedImgMaxWidth as per your need
I tried two different ways to create a screenshot, but unfortunately they don't work as I need, I have an RMMapView that is blank on the screenshot. When I create snapshot manually on my device it works perfectly, and the map view is on the screen. So I would like to achieve the same result programmatically. Is it possible somehow as I tried? Or what is the right way to do that? (To reproduce that type of screenshot)
- (UIImage *) takeScreenshot {
//1. version
UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, NO, [UIScreen mainScreen].scale);
[self.view drawViewHierarchyInRect:self.view.bounds afterScreenUpdates:YES];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
//2. version
UIGraphicsBeginImageContext(self.view.bounds.size);
CGContextRef context=UIGraphicsGetCurrentContext();
[self.view.layer renderInContext:context];
UIImage *image=UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
Actually You can use a method called takeSnapshot in a RMMapView.
UIImage *image = self.mapView.takeSnapshot
[Update]
Can you try this method instead
CGSize size = self.view.bounds.size;
CGRect cropRect = self.mapView.bounds
UIGraphicsBeginImageContext(size);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage * mapImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGImageRef imageRef = CGImageCreateWithImageInRect(mapImage.CGImage, cropRect);
UIImage * cropImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
UIImageWriteToSavedPhotosAlbum(cropImage, nil, nil, nil);
UIGraphicsEndImageContext();
Good luck
I am trying to combine two images into one. This is the code I am using:
UIImage* image1 = [UIImage imageNamed:#"1.tif"];
UIImage* image2 = [UIImage imageNamed:#"sign.tif"];
UIGraphicsBeginImageContext(image1.size);
[image1 drawInRect:CGRectMake(0, 0, image1.size.width, image1.size.height)];
[image2 drawInRect:CGRectMake(0, 0, image2.size.width, image2.size.height)];
UIImage *combinedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
imageView1.image = combinedImage;
It works perfectly in the simulator but does not work on the device. I get a white screen. Can any one please help me with this.
Any help will be appreciated.
Try to use this function:
- (UIImage * ) mergeImage: (UIImage *) imageA
withImage: (UIImage *) imageB
strength: (float) strength {
UIGraphicsBeginImageContextWithOptions(CGSizeMake([imageA size].width,[imageA size].height), NO, 0.0);
[imageA drawAtPoint: CGPointMake(0,0)];
[imageB drawAtPoint: CGPointMake(0,0)
blendMode: kCGBlendModeNormal // you can play with this
alpha: strength]; // 0 - 1
UIImage *mergedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return mergedImage;
}
And call it like this:
UIImage* image1 = [UIImage imageNamed:#"1.tif"];
UIImage* image2 = [UIImage imageNamed:#"sign.tif"];
UIImage *mergedImage =[self mergeImage:image1 withImage:image2 strength:1];