I'm creating many colour variations of an image using Core Graphics. I need to create about 320 in total but gradually, the memory usage of the app keeps increasing until it crashes. From Instruments, I see that more CGImage objects are being created and stay alive. I want to release them because I store the images to the cache directory in PNG format.
I have searched through all other solutions I could find without success. Any help is appreciated. Thanks.
Here's the main part:
+(UIImage *)tintedImageFromImage:(UIImage *)sourceImage colour:(UIColor *)color intensity:(float)intensity {
if (UIGraphicsBeginImageContextWithOptions != NULL) {
UIGraphicsBeginImageContextWithOptions(sourceImage.size, NO, 0.0);
} else {
UIGraphicsBeginImageContext(sourceImage.size);
}
CGContextRef context = UIGraphicsGetCurrentContext();
CGRect rect = CGRectMake(0, 0, sourceImage.size.width, sourceImage.size.height);
// draw alpha-mask
CGContextSetBlendMode(context, kCGBlendModeNormal);
CGContextDrawImage(context, rect, sourceImage.CGImage);
// draw tint color, preserving alpha values of original image
CGContextSetBlendMode(context, kCGBlendModeSourceIn);
[color setFill];
CGContextFillRect(context, rect);
//Set the original greyscale template as the overlay of the new image
sourceImage = [self verticallyFlipImage:sourceImage];
[sourceImage drawInRect:CGRectMake(0,0, sourceImage.size.width,sourceImage.size.height) blendMode:kCGBlendModeMultiply alpha:intensity];
UIImage *colouredImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
colouredImage = [self verticallyFlipImage:colouredImage];
return colouredImage;
}
this is used to flip the image:
+(UIImage *)verticallyFlipImage:(UIImage *)originalImage {
UIImageView *tempImageView = [[UIImageView alloc] initWithImage:originalImage];
UIGraphicsBeginImageContext(tempImageView.frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGAffineTransform flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0, tempImageView.frame.size.height);
CGContextConcatCTM(context, flipVertical);
[tempImageView.layer renderInContext:context];
UIImage *flippedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return flippedImage;
}
Add to verticallyFlipImage the line tempImageView.image = nil; in order to make the image view release the image. This solves the problem.
Related
I need to change the background color of the currently tabbed page in my UITabBarController. I've searched through every stackoverflow post I could find but nothing worked for me. I thought there would be something like UITabBar.Appearance.SelectedImageTintColor, just for the background color but it doesn't seem so.
For example, I want to change the color of that part when I am on the right tab:
Does someone know how to do that?
You could invoked the following code in your UITabBarController
public xxxTabBarController()
{
//...set ViewControllers
this.TabBar.BarTintColor = UIColor.Red;
}
Update
//3.0 here is if you have three child page in tab , set it as the current value in your project
//
var size = new CGSize(TabBar.Frame.Width / 3.0, IsFullScreen());
this.TabBar.SelectionIndicatorImage = ImageWithColor(size,UIColor.Green);
double IsFullScreen()
{
double height = 64;
if (UIDevice.CurrentDevice.CheckSystemVersion(11, 0))
{
if (UIApplication.SharedApplication.Delegate.GetWindow().SafeAreaInsets.Bottom > 0.0)
{
height = 84;
}
}
return height;
}
UIImage ImageWithColor(CGSize size, UIColor color)
{
var rect = new CGRect(0, 0, size.Width, size.Height);
UIGraphics.BeginImageContextWithOptions(size, false, 0);
CGContext context = UIGraphics.GetCurrentContext();
context.SetFillColor(color.CGColor);
context.FillRect(rect);
UIImage image = UIGraphics.GetImageFromCurrentImageContext();
UIGraphics.EndImageContext();
return image;
}
The trick is to use the SelectionIndicatorImage Property of the UITabBar and generate a completely filled image with your desired color using the following method:
private UIImage ImageWithColor(CGSize size)
{
CGRect rect = new CGRect(0, 0, size.Width, size.Height);
UIGraphics.BeginImageContext(size);
using (CGContext context = UIGraphics.GetCurrentContext())
{
context.SetFillColor(UIColor.Green); //change color if necessary
context.FillRect(rect);
}
UIImage image = UIGraphics.GetImageFromCurrentImageContext();
UIGraphics.EndImageContext();
return image;
}
To initialize everything we override ViewWillLayoutSubviews() like this:
public override void ViewWillLayoutSubviews()
{
base.ViewWillLayoutSubviews();
// The tabbar height will always be 49 unless we force it to reevaluate it's size on runtime ...
myTabBar.InvalidateIntrinsicContentSize();
double height = myTabBar.Frame.Height;
CGSize size = new CGSize(new nfloat(myTabBar.Frame.Width / myTabBar.Items.Length, height));
// Now get our all-green image...
UIImage image = ImageWithColor(size);
// And set it as the selection indicator
myTabBar.SelectionIndicatorImage = image;
}
As mentioned in this article (google translating it step by step when necessary lol) calling InvalidateIntrinsicContentSize() will force the UITabBar to reevaluate it's size and will get you the actual runtime height of the tab bar (instead of the constant 49 height value from XCode).
I have developed a project, where a user draws a image on a canvas, I store it in the file using CoreData, I have one-to-many relationship called folder-to-files. So here all are images. I retrive the images from files , resize according to my table cell height and show it on a table. Once it is shown, I want to cache the images.
I also have some labels on the folder cell, which give me some info regarding my files, which I update on fly.
I also swipe the cells to mark it complete and move it to the bottom the cell.
I also show same file images in different Views depending on how user queries it.
I want to know the best method for this, I read through the web, their are many methods, GCD, NSOperationQueues and many more.
Which method will be best suited for me.
I want to show some code
- (UITableViewCell *)tableView:(FMMoveTableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
FolderCell *tableCell = (FolderCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (tableCell == nil)
{
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:#"FolderCell" owner:self options:nil];
tableCell = [nib objectAtIndex:0];
}
NSMutableArray *categoryArray = [[self.controller fetchedObjects]mutableCopy];
Folder *category = [categoryArray objectAtIndex:[indexPath row]];
[tableCell configureCellWithNote:category]; //This function is written in my FolderCell.m function
}
return tableCell;
}
-(void)configureCellWithNote:(Folder *)category
{
self.category = category;
UIImage *image1 = [UIImage imageWithData:category.noteImage];
CGSize newSize;
if(image1.size.width == 620 && image1.size.height == 200)
{
newSize = CGSizeMake(300, 97);
}
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image1 drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
self.notesImage.image = newImage;
}
So what is happening here is that configureCellWithNote is taking lot of time, because it is resizing images. Please help me out in deciding how can this performance issue be solved.
Regards
Rajit
If you simply want to shuffle the resize operation to a background thread, you could do something like this:
- (void)configureCellWithNote:(Folder *)category
{
self.category = category;
UIImage *image1 = [UIImage imageWithData:category.noteImage];
CGSize newSize;
if(image1.size.width == 620 && image1.size.height == 200)
{
newSize = CGSizeMake(300, 97);
}
dispatch_async(dispatch_get_global_queue(0,0), ^{
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image1 drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
dispatch_async(dispatch_get_main_queue(), ^{
self.notesImage.image = newImage;
});
});
}
If you want to cache the results, then the trick will be to come up with a good cache key. Unfortunately, it's hard to tell from what you've posted what would make a good cache key. Certainly it will need to include the size, but it'll also need to include something that ties it back to the category. I suppose if nothing else you could use the NSManagedObjectID for the category, but I think that'll be specific to each managed object context you have. Assuming there was a property on Folder called uniqueName a caching implementation might look like this:
- (UIImage*)imageForCategory: (Folder*)category atSize: (CGSize)size
{
// A shared (i.e. global, but scoped to this function) cache
static NSCache* imageCache = nil;
// The following initializes the cache once, and only once
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
imageCache = [[NSCache alloc] init];
});
// Generate a cache key sufficient to uniquely identify the image we're looking for
NSString* cacheKey = [NSString stringWithFormat: #"%#|%#", category.uniqueName, NSStringFromSize((NSSize)size)];
// Try fetching any existing image for that key from the cache.
UIImage* img = [imageCache objectForKey: cacheKey];
// If we don't find a pre-existing one, create one
if (!img)
{
// Your original code for creating a resized image...
UIGraphicsBeginImageContextWithOptions(size, NO, 0.0);
UIImage* image1 = [UIImage imageWithData:category.noteImage];
[image1 drawInRect:CGRectMake(0,0,size.width,size.height)];
img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// Now add the newly-created image to the cache
[imageCache setObject: img forKey: cacheKey];
}
// Return the image
return img;
}
Resize MKAnnotationView Image When map zooms in and out? This methord are successful on iOS5, but failed on iOS6.
I change the MKAnnotationView's transform directly, and no luck. The MKAnnotationView only resize in a flash(When touch up inside the MKMapView, after the touch up finish, the MKAnnotationView will restore the original size).
My code are below:
- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated {
for (id <MKAnnotation>annotation in _mapView.annotations) {
// if it's the user location, just return nil.
if ([annotation isKindOfClass:[MKUserLocation class]])
continue;
// handle our custom annotations
//
if ([annotation isKindOfClass:[XPMKAnnotation class]])
{
// try to retrieve an existing pin view first
MKAnnotationView *pinView = [_mapView viewForAnnotation:annotation];
//resize the pin view
double zoomLevel = [_mapView getZoomLevel];
double scale = (1.0 * zoomLevel / 16) + 0.5;
pinView.transform = CGAffineTransformMakeScale(scale, scale);
}
}
}
Can we resize the MKAnnotationView on iOS6? Anybody know any way?
Apple suggests resizing the .image property of an annotation view. In my case shown below, I looked at the UIImage that was set in the viewforAnnotation and re-scaled it to the zoom level in a UIPinchGestureRecognizer
UIImage *orangeImage = [UIImage imageNamed:#"Orange210.PNG"];
CGRect resizeRect;
//rescale image based on zoom level
resizeRect.size.height = orangeImage.size.height * scale;
resizeRect.size.width = orangeImage.size.width * scale ;
NSLog(#"height = %f, width = %f, zoomLevel = %f", resizeRect.size.height, resizeRect.size.width,zoomLevel );
resizeRect.origin = (CGPoint){0,0};
UIGraphicsBeginImageContext(resizeRect.size);
[orangeImage drawInRect:resizeRect];
UIImage *resizedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
pinView.image = resizedImage;
I am trying to built an animated circle which would be drawn clockwise until it becomes complete circle as illustrated in iPhone Core Animation - Drawing a Circle
Problem is that CALayer object is not added or build. I tested and saw that it is not accessing my drawInContext:CGContextRef and animatingArc methods.
What so far I have done is:
In AnimateArc.h
#interface AnimateArc : CALayer {
CAShapeLayer *circle;
}
-(void) animatingArc;
#end
In AnimateArc.m
-(void) drawInContext:(CGContextRef)ctx
{
CGFloat radius = 50.0;
circle = [CAShapeLayer layer];
//make a circular shape
circle.path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0.0, 0.0, 2 * radius, 2 * radius) cornerRadius:radius].CGPath;
CGPoint centerPoint = CGPointMake(CGRectGetWidth(self.bounds)/2, CGRectGetHeight(self.bounds)/2);
//center the shape in self.view
circle.position = centerPoint;
//configure appearence of circle
circle.fillColor = [UIColor clearColor].CGColor;
circle.strokeColor = [UIColor blackColor].CGColor;
circle.lineWidth = 5;
/*CGPointMake((self.contentsCenter.size.width), (self.contentsCenter.size.height));*/
//path the circle
CGContextAddArc(ctx, centerPoint.x, centerPoint.y, radius, 0.0, 2 * M_PI, 0);
CGContextClosePath(ctx);
//fill it
CGContextSetFillColorWithColor(ctx, [UIColor redColor].CGColor);
CGContextFillPath(ctx); }
///////////////////////////////////////////////////////////////////////
-(void) animatingArc
{
CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:#"arcEnd"];
anim.duration = 20.0; //animate over 20 seconds
anim.repeatCount = 1.0; //animate only once
anim.removedOnCompletion = NO; //Reamin there after completion
//animate from start to end
anim.fromValue = [NSNumber numberWithFloat:50.0f];
anim.toValue = [NSNumber numberWithFloat:150.0f];
//experiment with timing to get appearence to look the way you want
anim.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
//add animation to circle
[circle addAnimation:anim forKey:#"animatingArc"];
}
/////////////////////
//needed since key not part of animatable properties
+(BOOL) needsDisplayForKey:(NSString *)key
{
if([key isEqualToString:#"arcEnd"])
return YES;
else
return [super needsDisplayForKey:key];
}
//ensure custom properties copied to presentation layer
-(id) initWithLayer:(id)layer
{
if((self = [super initWithLayer:layer]))
{
if ([layer isKindOfClass:[AnimateArc class]])
{
AnimateArc *other = (AnimateArc *) layer;
[other setNeedsDisplay];
}
}
return self; }
And finally in my viewController,
- (void)viewDidLoad
{
[super viewDidLoad];
[self.view.layer addSublayer:AnimateArcObject];
[AnimateArcObject animatingArc];
}
Apology for bad formatting.... Please can someone tell me what am I doing wrong? I have also doubt that my code can crash at any place after accessing those two functions since I am novice about Core Animation and haven't got any idea that I am in right direction or not.
Any help will be appreciated. Thanks.
From my painful experience with CoreAnimation, you must always set the bounds property of any CALayer you instantiate.
So, you're layer is not showing because you are missing something like:
layer.bounds = CGRectMake(0, 0, width, height);
you should place this as soon as you instantiate the layer, and make it a habit to do so, so you don't fall into it again.
As for your code crashing, sorry. It's too distributed and I am not sure how it's linked together, so I can't help you there.
After little searching, I thought that I am going in wrong direction. So I deleted this AnimateArc file and added new one which is inheriting from UIViewController.
Then in viewDidLoad Method, I wrote the code from this link to create circle and animations using path.
In parent view controller, I added AnimatedArc ViewController's subview. Now its working perfectly :)
I'm working on an Acne app in which I have to choose image from UIImagePicker and after adding subViews to it I want to save it in camera roll.
Problem: If I add UIImageView as a subView to the superView, the pickerImage does not save with subView.
And if I add that UIImage as subView to the Picker Image, I am unable to move the added UIImage Views.
I am using the following code for saving images:
-(IBAction)savePhoto
{
NSParameterAssert(imgToDisplayFromPicker.image);
UIImageWriteToSavedPhotosAlbum(imgToDisplayFromPicker.image, nil, nil, nil);
}
Finally Found the Solution :
CGRect contextRect = CGRectMake(6, 6, 302, 230);
UIGraphicsBeginImageContext(contextRect.size);
[self.view.layer renderInContext : UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGImageRef imageRef = CGImageCreateWithImageInRect([viewImage CGImage], contextRect);
UIImage * newImage = [UIImage imageWithCGImage:imageRef scale:1.0 orientation:viewImage.imageOrientation];
UIImageWriteToSavedPhotosAlbum(newImage, nil, nil, nil);