Environment: Xcode 5.0.2/iOS 7
Goal: to merely move a layer from point 'A' to point 'B'.
Problem: the 'move' acts like a 'copy'.
I've tried 2 move paradigms:
1) set the layer's position; and
2):
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"position"];
animation.fromValue = [layer valueForKey:#"position"];
animation.toValue = [NSValue valueWithCGPoint:point];
layer.position = point;
[layer addAnimation:animation forKey:#"position"];
Note: The CALayer # destination is accessible and am able to remove it from its container layer.
The CALayer # origin apparently is orphaned.
Question: what would cause this 'move' to act as a 'copy'?
Any remedy?
Weird Note: this code works correctly within a different UIViewController's view.
The problem stemmed from setting up the CALayers within UIViewController`s
- (void)viewDidLayoutSubviews {} <-- don't setup CALayers here!
rather than the correct:
- (void)viewDidLoad {} <-- preferred spot.
Creating CALayers within viewdidLayoutSubviews{} causes any position change to COPY vs MOVE.
However, creating CALayers within viewDidLoad{} behaves correctly: any position change is a MOVE.
Seems like a bug to me.
Related
I have a CVPixelBuffer that I'm trying to efficiently draw on screen.
The not-efficient way of turning into an NSImage works but is very slow, dropping about 40% of my frames.
Therefore, I've tried rendering it on-screen using CIContext's drawImage:inRect:fromRect. The CIContext was initialized with a NSOpenGLContext who's view was set to my VC's view. When I have a new image, I call the drawImage method which doesn't spit out any errors... but doesn't display anything on screen either (it did log errors when my contexts were not correctly setup).
I've tried to find an example of how this is done on MacOS, but everything seems to be for iOS nowadays.
EDIT:
Here's some of the code I am using. I've left out irrelevant sections
On viewDidLoad I init the GL and CI contexts
NSOpenGLPixelFormatAttribute pixelFormatAttr[] = {
kCGLPFAAllRenderers, 0
};
NSOpenGLPixelFormat *glPixelFormat = [[NSOpenGLPixelFormat alloc] initWithAttributes: pixelFormatAttr];
NSOpenGLContext *glContext = [[NSOpenGLContext alloc] initWithFormat:glPixelFormat shareContext:nil];
glContext.view = self.view;
self.ciContext = [CIContext contextWithCGLContext:glContext.CGLContextObj pixelFormat:glPixelFormat.CGLPixelFormatObj colorSpace:nil options:nil];
Then, when a new frame is ready, I do:
dispatch_async(dispatch_get_main_queue(), ^{
[vc.ciContext drawImage:ciImage inRect:vc.view.bounds fromRect:ciImage.extent];
vc.isRendering = NO;
});
I am not sure I'm calling draw in the right place, but I can't seem to find out where is this supposed to go.
If the CVPixelBuffer has the kCVPixelBufferIOSurfaceCoreAnimationCompatibilityKey attribute, the backing IOSurface (retrieved via CVPixelBufferGetIOSurface) can be passed directly to the contents property of a CALayer.
This is probably the most efficient way to display a CVPixelBuffer.
I set off to transform an NSImageView. My initially attempt was
self.imageView.wantsLayer = YES;
self.imageView.layer.transform = CATransform3DMakeRotation(1,1,1,1);
Unfortunately I noticed that the transform only happens sometimes (maybe once every 5 runs). Adding an NSLog between confirmed that on some runs self.imageView.layer is null. State of the whole project is shown on the image below.
It's an incredibly simple 200x200 NSImageView with an outlet to a generated NSViewController. Some experimentation showed settings wantsDisplay doesn't fix the problem, but putting the transform on an NSTimer makes it work every-time. I'd love an explanation why this happens (I presume it's due to some race condition).
I'm using Xcode 8 on the macOS 10.12 but I doubt this is the cause of the problem.
Update
Removing wantsLayer and madly enabling Core Animation Layers in Interface Builder did not fix the problem.
Neither did attempts to animate it (I wasn't sure what I was hoping for)
// Sometimes works.. doesn't animate
[NSAnimationContext runAnimationGroup:^(NSAnimationContext *context) {
context.duration = 1;
self.imageView.animator.layer.transform = CATransform3DMakeRotation(1,1,1,1);
} completionHandler:^{
NSLog(#"Done");
}];
or
// Animates but only sometimes
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"transform"];
animation.toValue = [NSValue valueWithCATransform3D:CATransform3DMakeRotation(1,1,1,1)];
animation.duration = 1;
[self.imageView.layer addAnimation:animation forKey:nil];
After experimenting with allowsImplicitAnimation I realised I might be trying to animate too early.
Moving the transform code into viewDidAppear made it work every time.
- (void)viewDidAppear {
[super viewDidAppear];
self.imageView.animator.layer.transform = CATransform3DMakeRotation(1,1,1,1);
}
I am implementing a CCLayer subclass that houses 2 UIImageViews. The views and layer are all the same size: I initialized the UIImageViews with the same frame, and set the contentSize of the layer to be the frame as well. Everything is working fine, but it seems as though something is going haywire with the first point when drawing. When the image is just tapped there is no line jump, but when I attempt to draw a stroke, as soon as I move my finger, the start of the line jumps down randomly(so in this screenshot I am drawing from left to right except for bottom-left line). I am not sure where I am going wrong in my code:
//_drawImageView is the UIImageView I am drawing in.
#pragma mark - Touch Methods
- (BOOL)ccTouchBegan:(UITouch *)touch withEvent:(UIEvent *)event
{
penStroked = NO;
_prevPoint = [touch locationInView:[[CCDirector sharedDirector]view]];
CGRect rect = self.boundingBox;
if (CGRectContainsPoint(rect, _prevPoint)) {
return YES;
}
return NO;
}
- (void)ccTouchMoved:(UITouch *)touch withEvent:(UIEvent *)event
{
penStroked = YES;
_currPoint = [touch locationInView:_drawImageView];
UIGraphicsBeginImageContext(self.contentSize);
[_drawImageView.image drawInRect:CGRectMake(0, 0, _drawImageView.frame.size.width, _drawImageView.frame.size.height)];
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), _prevPoint.x, _prevPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), _currPoint.x, _currPoint.y);
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), penSize);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), penColor.r, penColor.g, penColor.b, 1.0);
CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeNormal);
CGContextStrokePath(UIGraphicsGetCurrentContext());
_drawImageView.image = UIGraphicsGetImageFromCurrentImageContext();
[_drawImageView setAlpha: penOpacity];
UIGraphicsEndImageContext();
_prevPoint = _currPoint;
}
I was having a really hard time initially aligning the point at which the line would be draw n and the actual position of my finger, so that is why in the ccTouchBegan method the touch is taken from the CCDirector and in ccTouchMoved it is taken from the _drawImageView. This is the only way it seems to draw perfectly besides the initial wonky behavior.
The problem was definitely caused by the differing references for the touches. As I had said before though, it was the only way to have the line match the position my finger was in. I figured that the line jump was due to the line of code:
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), _prevPoint.x, _prevPoint.y);
The problem was that on the first go around, or the first time that the pen/finger is stroked, the previous point was referenced from the CCDirectors view while the current point was from the imageView. I created an int variable, that was incremented every time the pen was stroked and when penStrokedInt == 1 (first stroke), I corrected the _prevPoint to the WorldSpace using the current point coordinates:
_prevPoint = [self convertToWorldSpace:_currPoint];
which basically got rid of the very first point in the line. It's not the best solution, but now it works! Make sure to reset the penStrokedInt back to 0 when the ccTouchEnded.
I'm writing an app (XCode 4.6) that displays drawings of various different paths - for now it's just straight lines and bezier paths, but eventually it will get more complicated. I am currently not using any layers and the display is actually pretty simple.
my drawRect code looks like this:
- (void)drawRect:(CGRect)rect :(int) points :(drawingTypes) type //:(Boolean) initial
{
//CGRect bounds = [[UIScreen mainScreen] bounds];
CGRect appframe= [[UIScreen mainScreen] applicationFrame];
CGContextRef context = UIGraphicsGetCurrentContext();
_helper = [[Draw2DHelper alloc ] initWithBounds :appframe.size.width :appframe.size.height :type];
CGPoint startPoint = [_helper generatePoint] ;
[_uipath moveToPoint:startPoint];
[_uipath setLineWidth: 1.5];
CGContextSetStrokeColorWithColor(context, [UIColor lightGrayColor].CGColor);
CGPoint center = CGPointMake(self.center.y, self.center.x) ;
[_helper createDrawing :type :_uipath :( (points>0) ? points : defaultPointCount) :center];
[_uipath stroke];
}
- (void)drawRect:(CGRect)rect
{
if (_uipath == NULL)
_uipath = [[UIBezierPath alloc] init];
else
[_uipath removeAllPoints];
[self drawRect:rect :self.graphPoints :self.drawingType ];
}
The actual path is generated by a helper object (_helper). I would like to animate the display of this path to appear slowly over a few seconds as it is being drawn - what is the easiest and fastest way of doing this?
What do you mean "appear slowly?" I assume you do not mean fade in all over at once, but rather mean that you want it to look like the path is being drawn with a pen?
To do that, do the following:
Create a CAShapeLayer the same size as your view and add it as a sublayer of your view.
Get the CGPath from your bezier path.
Install the CGPath into your shapeLayer.
Create a CABasicAnimation that animates the value of the shape layer's strokeEnd property from 0.0 to 1.0. That will cause the shape to be drawn as if it was being traced from beginning to end. You probably want a path that contains a single, contiguous sub-path. If you want it to circle back and connect, make it a closed path.
There are all kinds of cool tricks you can do with shape layers and animating changes to the path. and it's settings (like strokeStart and strokeEnd, stokeColor, fillColor, etc.) If you animate the path itself, you have to make sure the beginning path and ending path have the same number of control points internally. (And path arcs are tricky because the path has a different number of control points depending on the angle of the arc.)
I'm trying to slide in a NSView using core animation. I think I need to use explicit animation rather than relying on something like [[view animator] setFrame:newFrame]. This is mainly because I need to set the animation delegate in order to take action after the animation is finished.
I have it working just fine using the animator, but as I said, I need to be notified when the animation finishes. My code currently looks like:
// Animate the controlView
NSRect viewRect = [controlView frame];
NSPoint startingPoint = viewRect.origin;
NSPoint endingPoint = startingPoint;
endingPoint.x += viewRect.size.width;
[[controlView layer] setPosition:NSPointToCGPoint(endingPoint)];
CABasicAnimation *controlPosAnim = [CABasicAnimation animationWithKeyPath:#"position"];
[controlPosAnim setFromValue:[NSValue valueWithPoint:startingPoint]];
[controlPosAnim setToValue:[NSValue valueWithPoint:endingPoint]];
[controlPosAnim setDelegate:self];
[[controlView layer] addAnimation:controlPosAnim forKey:#"controlViewPosition"];
This visually works (and I get notified at the end) but it looks like the actual controlView doesn't get moved. If I cause the window to refresh, the controlView disappears. I tried replacing
[[controlView layer] setPosition:NSPointToCGPoint(endingPoint)];
with
[controlView setFrame:newFrame];
and that does cause the view (and layer) to move, but it is corrupting something such that my app dies with a seg fault soon afterwards.
Most of the examples of explicit animation seem to only be moving a CALayer. There must be a way to moving the NSView and also being able to set a delegate. Any help would be appreciated.
Changes made to views take effect at the end of the current run loop. The same goes for any animations applied to layers.
If you animate a view's layer, the view itself is unaffected which is why the view appears to jump back to its original position when the animation completes.
With these two things in mind, you can get the effect you want by setting the view's frame to what you want it to be when the animation is done and then adding an explicit animation to the view's layer.
When the animation begins, it moves the view to the starting position, animates it to the end position and when the animation is done, the view has the frame you specified.
- (IBAction)animateTheView:(id)sender
{
// Calculate start and end points.
NSPoint startPoint = theView.frame.origin;
NSPoint endPoint = <Some other point>;
// We can set the frame here because the changes we make aren't actually
// visible until this pass through the run loop is done.
// Furthermore, this change to the view's frame won't be visible until
// after the animation below is finished.
NSRect frame = theView.frame;
frame.origin = endPoint;
theView.frame = frame;
// Add explicit animation from start point to end point.
// Again, the animation doesn't start immediately. It starts when this
// pass through the run loop is done.
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"position"];
[animation setFromValue:[NSValue valueWithPoint:startPoint]];
[animation setToValue:[NSValue valueWithPoint:endPoint]];
// Set any other properties you want, such as the delegate.
[theView.layer addAnimation:animation forKey:#"position"];
}
Of course, for this code to work you need to make sure both your view and its superview have layers. If the superview doesn't have a layer, you'll get corrupted graphics.
I think you need to call the setPosition at the end (after setting the animation).
Also, I don't think you should animate explicitely the layer of the view, but instead the view itself by using animator and setting the animations. You can use delegates too with animator :)
// create controlPosAnim
[controlView setAnimations:[NSDictionary dictionaryWithObjectsAndKeys:controlPosAnim, #"frameOrigin", nil]];
[[controlView animator] setFrame:newFrame];