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• Intermittent fillMode=kCAFillModeForwards bug using CAKeyframeAnimation with path

  - by Mark24x7

  I'm having an intermittent problem when I move a UIImageView around the screen using CAKeyframeAnimation. I want the position of the UIImageView to remain where the animation ends when it is done. This bug only happens for certain start and end points. When I use random points it works correctly most of the time, but about 5-15% of the time it fails and snaps back to the pre-animation position. The problem only appears when using CAKeyframeAnimation using the path property. If I use the values property the bug does not appear. I am setting removedOnCompletion = NO, and fillMode = kCAFillModeForwards. I have posted a link to a test Xcode below. Here is my code for setting up the animation. I have a property usePath. When this is YES, the bug appears. When I set usePath to NO, the snap back bug does not happen. In this case I am using a path that is a simple line, but once I resolve this bug with a simple path, I will use a more complex path with curves in it. // create the point CAKeyframeAnimation *moveAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"]; if (self.usePath) { CGMutablePathRef path = CGPathCreateMutable(); CGPathMoveToPoint(path, NULL, startPt.x, startPt.y); CGPathAddLineToPoint(path, NULL, endPt.x, endPt.y); moveAnimation.path = path; CGPathRelease(path); } else { moveAnimation.values = [NSArray arrayWithObjects: [NSValue valueWithCGPoint:startPt], [NSValue valueWithCGPoint:endPt], nil]; } moveAnimation.calculationMode = kCAAnimationPaced; moveAnimation.duration = 0.5f; moveAnimation.removedOnCompletion = NO; // leaves presentation layer in final state; preventing snap-back to original state moveAnimation.fillMode = kCAFillModeForwards; moveAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut]; // moveAnimation.delegate = self; // start the animation [ball.layer addAnimation:moveAnimation forKey:@"moveAnimation"]; To dl and view my test project goto test project (http://www.24x7digital.com/downloads/PathFillModeBug.zip) Tap the 'Move Ball' button to start the animation of the ball. I have hard coded a start and end point which causes the bug to happen every time. Use the switch to change usePath to YES or NO. When usePath is YES, you will see the snap back bug. When usePath is NO, you will not see the snap back bug. I'm using SDK 3.1.3, but I have seen this bug using SDK 3.0 as well, and I have seen the bug on the Sim and on my iPhone. Any idea on how to fix this or if I am doing something wrong are appreciated. Thanks, Mark.

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• How to create a "Clustergram" plot ? (in R)

  - by Tal Galili

  Hi all, I came across this interesting website, with an idea of a way to visualize a clustering algorithm called "Clustergram": I am not sure how useful this really is, but in order to play with it I would like to reproduce it with R, but am not sure how to go about doing it. How would you create a line for each item so it would stay consistent throughout the different number of clusters? Here is an example code/data to play with for potential answer: hc <- hclust(dist(USArrests), "ave") plot(hc)

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• Algorithm for Text Wrapping Within a Shape

  - by devongovett

  I am looking for an algorithm to wrap text within a non-rectangular shape, preferably based on the Knuth and Plass algorithm. The hardest part of this is that the lines may have different heights due to differing font sizes in the text. The image below is an example of what the algorithm should be able to generate. Thanks for any help!

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• Text to speech on iPhone

  - by lostInTransit

  Hi Is there any way we can convert text to speech in an iPhone app? Is it possible using the SDK? Thanks Are there any third-party TTS engines available for the iPhone? (AFAIK Acapela is not yet released)

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• SVG to Android Shape

  - by Buggieboy

  I have started learning about vector drawing in Android with the Shape class. Since Shape is a Drawable, and Drawables are usually defined as XML, it sounds a lot like the vector drawing commands in SVG. My question is this: Has anybody created an XSLT transformation, or other mechanism, for converting an SVG drawing description into Android Shapes?

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• Issue with CAAnimation and CALayer Transforms

  - by Brian

  I have a CALayer that I want to animate across the screen. I have created two methods: one slide open the layer and one to slide close. These both work by assigning a property to the layer's transform property. Now I want to use a CAKeyFrameAnimation to slide open the layer. I got this working so the layer slides open, but now I can't slide the layer close using my old method. I am trying to figure out why this is. Any help would be great. Code: - (id)init { if( self = [super init] ) { bIsOpen = NO; closeTransform = self.transform; openTransform = CATransform3DMakeTranslation(-235.0, 0.0, 0.0); } return self; } - (void)closeMenu { if( bIsOpen ) { self.transform = closeTransform; bIsOpen = !bIsOpen; } } - (void)openMenu { if( !bIsOpen ) { CAKeyframeAnimation *closeAnimation = [CAKeyframeAnimation animationWithKeyPath:@"transform"]; closeAnimation.duration = 1.0; closeAnimation.removedOnCompletion = NO; closeAnimation.fillMode = kCAFillModeForwards; closeAnimation.values = [NSArray arrayWithObjects:[NSValue valueWithCATransform3D:closeTransform],[NSValue valueWithCATransform3D:openTransform],nil]; closeAnimation.timingFunctions = [NSArray arrayWithObject:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]]; [self addAnimation:closeAnimation forKey:@"transform"]; bIsOpen = !bIsOpen; } }

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• Purpose of CALayer?

  - by jasonbogd

  Hi, I'm slightly used as to what the purpose of CALayer's existence is. Why not just put the properties in a UIView? Thanks.

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• Encode complex number as RGB pixel

  - by Vi

  How is it better to encode a complex number into RGB pixel and vice versa? Probably (logarithm of) an absolute value goes to brightness and an argument goes to hue. Desaturated pixes should receive randomized argument in reverse transformation. Something like: 0 - (0,0,0) 1 - (255,0,0) -1 - (0,255,255) 0.5 - (128,0,0) i - (255,255,0) -i - (255,0,255) (0,0,0) - 0 (255,255,255) - e^(i * random) (128,128,128) - 0.5 * e^(i *random) (0,128,128) - -0.5 Are there ready-made formulas for that?

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• Quartz 2D: draw from a CGContext to another CGContext

  - by alexey

  I have a CGBitmapContext (bitmapContext) and I would like to draw some rectangle part (rect) of it to the current CGContext (context). Right now I do that way: CGContextRef context = UIGraphicsGetCurrentContext(); CGImageRef cgImage = CGBitmapContextCreateImage(bitmapContext); CGContextClipToRect(context, rect); CGContextDrawImage(context, CGRectMake(0, 0, width, height), cgImage); CGImageRelease(cgImage); Is it optimal? What is the best way to do it?

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• Millions of 3D points: How to find the 10 of them closest to a given point?

  - by Kazoom

  A point in 3-d is defined by (x,y,z). Distance d between any two points (X,Y,Z) and (x,y,z) is d= Sqrt[(X-x)^2 + (Y-y)^2 + (Z-z)^2]. Now there are a million entries in a file, each entry is some point in space, in no specific order. Given any point (a,b,c) find the nearest 10 points to it. How would you store the million points and how would you retrieve those 10 points from that data structure.

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• Programmatical Creation of NSMappingModel

  - by enchilada

  I want to programmatically (without Lightweight Migration) create a mapping model between two models that are exactly the same, except one of the entities (there are a bunch of entities) has different attributes. Let's call this entity "Person". And let's say the destination model has 1) added a new attribute called "address" 2) deleted an attribute called "eyeColor" 3) kept (i.e. not done anything with) an attribute called "name" How would you create an NSMappingModel between these models programmatically? I happen to have some explicit questions that might help me do this by myself: Q1) Do I have to create NSEntityMapping objects for all of the entities other than "Person", even if they remain unchanged? Q2) How do I deal with the "address" attribute in "Person", which is a new one being created? Should I create an NSPropertyMapping for that somehow, that turns nothing into something ("address")? Q3) How do I deal with the "name" attribute in "Person"? Do I have to create an NSPropertyMapping for that, even though it simply stays the same? Q4) For the NSEntityMapping corresponding to "Person", is not creating any NSPropertyMapping for "eyeColor" a proper way to get it deleted? Or should I create an NSPropertyMapping for "eyeColor"? If yes, how would this object be created, i.e. what would determine that its purpose is to get rid of "eyeColor"? Thank you in advance, and I apologize not being able to answer these questions myself, as the documenation really has no good example of how to create NSMappingModels programmatically. Note again that I'm not allowed to use Lightweight Migration. I must do this manually.

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• iPhone programming - problem with CoreFoundation forking

  - by Tom

  Hello all, I've been working on an iPhone for several months. It's a 2d shooting game akin to the old Smash TV type games. I'm doing everything alone and it has come out well so far, but now I am getting unpredictable crashes which seem to be related to CoreFoundation forking and not exec()ing, as the message __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONA LITY___YOU_MUST_EXEC__ always shows up somewhere in the debugger. Usually it shows up around a CFRunLoopRunSpecific and is related to either a timer firing or _InitializeTouchTapCount. I cannot figure out exactly what is causing the fork to occur. My main game loop is running on a timer, first updating all the logic and then drawing everything with openGL. There is nothing highly complex or unusual. I understand you cannot make CF calls on the childside of a fork, or access shared memory and things like that. I am not explicitly trying to fork anything. My question is: can anyone tell me what type of activity might cause CoreFoundation to randomly fork like this? I'd really like to finish this game and I don't know how to solve this problem. Thanks for any help.

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• Can I perform animations on a UIControl subclass with iPhone SDK 3.x?

  - by Elon

  I have a custom UIControl that passes UIControlEventValueChanged events back to my ViewController. I also need to animate it (basic resizing) in certain circumstances, but UIControl seems to have no implementation of beginAnimations or commitAnimations. Do I have to encase it in a UIView? Any better solution? Thanks.

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• efficient algorithm for drawing circle arcs?

  - by banister

  I am using the mid-point circle algorithm (bresenham circle) to efficiently draw whole circles. Is there something similar to draw circle arcs? I would like to specify a start angle and end angle and have only that portion of the circle drawn. Thanks in advance! EDIT: I would like to draw filled circle arcs too, i.e pie-slices. :)

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• trying to draw scaled UIImage in custom view, but nothing's rendering

  - by Ben Collins

  I've created a custom view class and right now just want to draw an image scaled to fit the view, given a UIImage. I tried just drawing the UIImage.CGImage, but as others have attested to on this site (and in the docs), that renders the image upside down. So, at the suggestion of an answer I found to another question, I'm trying to draw it directly, but nothing is rendering in the view and I'm not sure why. Here's my drawing code: - (void)drawRect:(CGRect)rect { // Drawing code [super drawRect:rect]; if (self.originalImage) { [self drawImage]; } } - (void) drawImage { if (CGSizeEqualToSize(originalImage.size, self.frame.size) == NO) { CGFloat scaleFactor = 1.0; CGFloat scaledWidth = 0.0; CGFloat scaledHeight = 0.0; CGPoint thumbPoint = CGPointMake(0.0, 0.0); CGFloat widthFactor = self.frame.size.width / originalImage.size.width; CGFloat heightFactor = self.frame.size.height / originalImage.size.height; if (widthFactor < heightFactor) { scaleFactor = widthFactor; } else { scaleFactor = heightFactor; } scaledWidth = originalImage.size.width * scaleFactor; scaledHeight = originalImage.size.height * scaleFactor; if (widthFactor < heightFactor) { thumbPoint.y = (self.frame.size.height - scaledHeight) * 0.5; } else if (widthFactor > heightFactor) { thumbPoint.x = (self.frame.size.width - scaledWidth) * 0.5; } UIGraphicsBeginImageContext(self.frame.size); CGRect thumbRect = CGRectZero; thumbRect.origin = thumbPoint; thumbRect.size.width = scaledWidth; thumbRect.size.height = scaledHeight; [originalImage drawInRect:thumbRect]; self.scaledImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); } else { self.scaledImage = originalImage; } } My understanding (after studying this a bit) is that the UIGraphicsBeginImageContext function creates an offscreen for me to draw into, so now how do I render that context on top of the original one?

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• Removing all CALayer's sublayers

  - by radex

  Hi. I have trouble with deleting all layer's sublayers. I do this manually, but it's unwanted code clutter. I found many topics about this in google, but no answer. I tried to do something like this: for(CALayer *layer in rootLayer.sublayers) { [layer removeFromSublayer]; } but it didn't work. Also, i tried to clone rootLayer.sublayers into separate NSArray, but result was the same. Any ideas? regards, radex PS. sorry for my English. Edit: I thought it works now, but I was wrong. It works good with CALayers, but it doesn't work with CATextLayers. Any ideas?

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• How to change the font size gradually in a UILabel?

  - by Flocked

  Hello, is there a way to change the font size gradually in a UILabel? I tried it with: [UIView beginAnimations:@"foo" context:nil]; [UIView setAnimationDuration:0.8]; uiLabel.font = [UIFont boldSystemFontOfSize:144]; [UIView commitAnimations]; The problem is that the change of the font size happens instantly.

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• Objective-C: fetchManagedObjectsForEntity problem

  - by Meko

  Hi.I am trying to get value from CoreData entity name Person with predicate and then comparing with new data in dictionary.But it it returns every time 0 .And it creates about 5 person with same name. NSPredicate *predicate = [NSPredicate predicateWithFormat:@"userName == %@",[flickr usernameForUserID:@"owner"]]; peopleList = (NSMutableArray *)[flickr fetchManagedObjectsForEntity:@"Person" withPredicate:predicate]; NSEnumerator *enumerator = [peopleList objectEnumerator]; Person *person; BOOL exists = FALSE; while (person = [enumerator nextObject]) { NSLog(@" Person is: %@ ", person.userName); NSLog(@"Person ID IS %@",person.userID); NSLog(@"Dict ID is %@",[dict objectForKey:@"owner"]); if([person.userID isEqualToString:[dict objectForKey:@"owner"]]) { exists = TRUE; NSLog(@"-- Person Exists : %@--", person.userName); [newPhoto setPerson:person]; } } Here peopleList returns 0 and the enumerator also 0 and it does not use if and not comparing.In my entity I have Person and Photo entities.In Person I have userName and userID attributes and also one-to many relationship with Photo entity. I think problem in predicate but i cant figure out it .

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• Updates to NSDictionary attribute in CoreData not saving

  - by sfkaos

  I have created an Entity in CoreData that includes a Transformable attribute type implemented as an NSDictionary. The NSDictionary attribute only contains values of a custom class. The properties of the custom class are all of type NSString. The custom class complies with NSCoding implementing: -(void)encodeWithCoder:(NSCoder*)coder; -(id)initWithCoder:(NSCoder *)coder When saving the Entity for the first time all attributes including the Transformable (NSDictionary) type are properly saved in the DB. When the same Entity is fetched from the DB and updated (including the Transformable attribute) it seems to be updated properly. However, when the app is closed and then reopened fetching the Entity does not show the updated Transformable attribute-type though the rest of the attributes of type NSDate and NSString are up-to-date. The Transformable attribute is the original saved value not the updated value. Is this a problem with KVO or am I missing something else when trying to save an NSDictionary filled with a custom class to CoreData?

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• millions of 3d points how to 10 closest to origin

  - by Kazoom

  A point in 3-d is defined by (x,y,z). Distance d between any two points (X,Y,Z) and (x,y,z) is d= Sqrt[(X-x)^2 + (Y-y)^2 + (Z-z)^2]. Now there are a million entries in a file, each entry is some point in space, in no specific order. Given any point (a,b,c) find the nearest 10 points to it. How would you store the million points and how would you retrieve those 10 points from that data structure.

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• CAShapeLayer slowing down interface rotation

  - by MrMage

  Hi, I am trying to move some custom drawing code from a view into a CAShapeLayer, which then get added as a sublayer to the original view's CALayer. This also works well, but when rotating the device, the animation starts to stutter, e.g. you just see the frame in the original orientation and then the final orientation, with at most one frame in between - not smooth at all. Slide-in and slide-out animations of the corresponding UIViewController are a bit jerky, too (but not that much). All the CAShapeLayer has in its path is one CGPathAddRect, it is set to be opaque, its opacity is 1.0f and the fillColor is set to opaque blue. When drawing the path directly in the views drawRect method, however, the animation is smooth. So I suppose it has something to do with the CAShapeLayer being animated during the rotation. Could you tell me how to either get rid of those jerkiness or just hide the CAShapeLayer when animating? Getting back to just draw CGPaths directly is not an option to me because I rely on the ability of CAShapeLayer to animate its path (it is not animated in my tries with rotating the view). /update: this also happens when the rotating UIViewControllers view contains a view with a subclass of CAGradientLayer as its layerClass (e.g. a view with a gradient layer as background). Cheers MrMage

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• AudioQueue in-memory playback example

  - by Jonesy

  Does anybody know of any examples using AudioQueue that play from an in-memory source? All the examples I can find play from files (using AudioFileReadPackets) but in my particular case I am generating the data myself in realtime so ideally, I want to enqueue the data myself rather than sucking it out of a file using the callback. Any help much appreciated.

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• Super wide, but not so tall, bitmap?

  - by Erik Karlsson

  Howdy folks. Is there any way to create a more space/resource efficient bitmap? Currently i try to render a file, approx 800 px high but around 720000px wide. It crashes my application, presumebly because of the share memory-size of the bitmap. Can i do it more efficient, like creating it as an gif directly and not later when i save it? I try to save a series of lines/rectangles from a real world reading, and i want it to be 1px per 1/100th of a second. Any input? And btw, i never manage to ogon using google open id : /

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• In OpenGL vertex shader, gl_Position doesn't get homogenized..

  - by KJ

  Hi everyone, I was expecting gl_Position to automatically get homogenized (divided by w), but it seems not working.. Why do the followings make different results? 1) void main() { vec4 p; ... omitted ... gl_Position = projectionMatrix * p; } 2) ... same as above ... p = projectionMatrix * p; gl_Position = p / p.w; I think the two are supposed to generate the same results, but it seems it's not the case. 1 doesn't work while 2 is working as expected.. Could it possibly be a precision problem? Am I missing something? This is driving me almost crazy.. helps needed. Many thanks in advance!

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• AudioQueueOfflineRender returning empty data

  - by hyn

  I'm having problems using AudioQueueOfflineRender to decode AAC data. When I examine the buffer after the call, it is always filled with empty data. I made sure the input buffer is valid and packet descriptions are provided. I searched and found that a few others have had the same problem: http://lists.apple.com/archives/Coreaudio-api/2008/Jul/msg00119.html Also, the inTimestamp argument doesn't make sense to me. Why should the renderer care where in the audio the beginning of the buffer corresponds to? The function throws an error if I pass in NULL, so I pass in the timestamp anyway.

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