CORE ANIMATION: HANDS-ON...GEOMETRY & TRANSFORMS • 2D cartesian coordinate system with origin in the top left • Quartz2D primitive data structures (CGPoint, CGRect, etc.) • Each

CORE ANIMATION: HANDS-ONBuilding Complex and Attractive Cocoa Touch Interfaces

© 2009 Nathan Eror & Free Time Studios

Nathan Eror - Free Time Studios

http://www.neror.com/


http://www.freetimestudios.com/









































































WHO AM I?• Nathan Eror - Free Time Studios

• 10 years as a developer (8 of those on a Mac ☻)

• Game console tools

• Java 2D graphics library

• Web and Hosting

• iPhone SDK since the beginning













































































WTF?• Core Animation

• Lots of detail

• A lot of code (>1400 lines of it!)

• Get the code at github: http://github.com/neror/CA360

• Here we go!


http://github.com/neror/CA360

http://github.com/neror/CA360












































































WHAT IS CORE ANIMATION?(Surprise! It’s Not Only About Animation.)

• Compositing and animation API created for Cocoa Touch

• Hierarchical collection of layers

• Highly optimized for speed (only draws when necessary)

• Interpolates animations away from the main thread

• Simple API (most of the time)

• Hardware accelerated for high performance













































































CORE ANIMATION & UIKIT• Core Animation is at the heart of UIKit

• It was originally designed for Cocoa Touch and ported to Leopard

• A UIView is essentially a CALayer with touch event handling

• A UIView is composed of a single CALayer and is the layer’s drawing delegate (more about that later)


UIView.hUIKIT_EXTERN_CLASS @interface UIView : UIResponder<NSCoding> { @package CALayer *_layer;}

// default is [CALayer class]. Used when creating the underlying layer for the view.+ (Class)layerClass;

// returns view's layer. Will always return a non-nil value. view is layer's delegate@property(nonatomic,readonly,retain) CALayer *layer;












































































CORE ANIMATION IPHONECLASS HIERARCHY













































































LAYER GEOMETRY&

TRANSFORMS













































































GEOMETRY & TRANSFORMS• 2D cartesian coordinate system with origin in the top left

• Quartz2D primitive data structures (CGPoint, CGRect, etc.)

• Each layer has its own coordinate system

• All geometric properties are animatable and have a default implicit animation

• A CALayer is a 2D plane projected in 3D

• The transition to the next slide is a good illustration of this


X

Y












































































GEOMETRY & TRANSFORMS

CALayer Geometric Properties@property CGRect bounds;

@property CGPoint position;

@property CGFloat zPosition;

@property CGPoint anchorPoint;

@property CGFloat anchorPointZ;

@property CATransform3D transform;

@property CGRect frame;


Quartz2D Data Structuresstruct CGPoint { CGFloat x; CGFloat y;};typedef struct CGPoint CGPoint;

struct CGSize { CGFloat width; CGFloat height;};typedef struct CGSize CGSize;

struct CGRect { CGPoint origin; CGSize size;};typedef struct CGRect CGRect;












































































3D Transform Properties

Parent Layer (L1)

L1.bounds.origin = (0,0)

L1.bounds.width = 500

L1.bounds.height = 400


L1.transform = CATransform3DIdentity

Child Layer (L2)

L2.bounds.height = 150

L2.bounds.width = 150

L2.bounds.origin = (0,0)

L2.anchorPoint = (0.5,0.5)

L2.frame.origin = (280,280)

L2.frame.width = 150

L2.frame.height = 150

L2.position = (355,355)

L2.transform = CATransform3DIdentity

L1.sublayerTransform = CATransform3DIdentity


X

Y














































































CODE DEMOGeometric Properties












































































GEOMETRY & TRANSFORMS3D Transformation Matrix Data Structurestruct CATransform3D{ CGFloat m11, m12, m13, m14; CGFloat m21, m22, m23, m24; CGFloat m31, m32, m33, m34; CGFloat m41, m42, m43, m44;};typedef struct CATransform3D CATransform3D;

CALayer’s 3D Transformation Properties@property CATransform3D transform;

@property CATransform3D sublayerTransform;

@property CGPoint anchorPoint;

@property CGFloat anchorPointZ;


CATransform3D Matrix OperationsCATransform3D CATransform3DMakeTranslation(CGFloat tx, CGFloat ty, CGFloat tz);

CATransform3D CATransform3DMakeScale(CGFloat sx, CGFloat sy, CGFloat sz);

CATransform3D CATransform3DMakeRotation(CGFloat angle, CGFloat x, CGFloat y, CGFloat z);

CATransform3D CATransform3DTranslate(CATransform3D t, CGFloat tx, CGFloat ty, CGFloat tz);

CATransform3D CATransform3DScale(CATransform3D t, CGFloat sx, CGFloat sy, CGFloat sz);

CATransform3D CATransform3DRotate(CATransform3D t,CGFloat angle,CGFloat x,CGFloat y,CGFloat z);

CATransform3D CATransform3DConcat(CATransform3D a, CATransform3D b);

CATransform3D CATransform3DInvert(CATransform3D t);














































































CODE DEMOLayer Transforms












































































CATransform3Drotation rotation.x rotation.y rotation.z

scale scale.x scale.y scale.z

translation translation.x translation.y translation.z


KEY VALUE CODINGAll CALayer properties are available through key paths//Scale the layer along the x-axis[layer setValue:[NSNumber numberWithFloat:1.5] forKeyPath:@"transform.scale.x"];

//Same result as aboveCGSize biggerX = CGSizeMake(1.5, 1.);[layer setValue:[NSValue valueWithCGSize:biggerX] forKeyPath:@"transform.scale"];

CGPointorigin size

origin.x size.width

origin.y size.height

CGSize

width

height

CGPoint

x

y

! Structures must be wrapped in an NSValue instance before being passed to setValue:forKeyPath:

Key Paths for Structure Fields:












































































LAYER HIERARCHY














































































Layer Tree Hierarchy Related Methods

LAYER TREE HIERARCHY• Layers are organized in a tree

• A layer is positioned, sized and transformed relative to its parent’s coordinate system and sublayerTransform

• By default, a parent layer does not clip its children to its bounds

@property(readonly) CALayer *superlayer; - (void)removeFromSuperlayer;@property(copy) NSArray *sublayers;

- (void)addSublayer:(CALayer *)layer;- (void)insertSublayer:(CALayer *)layer atIndex:(unsigned)idx;- (void)insertSublayer:(CALayer *)layer below:(CALayer *)sibling;- (void)insertSublayer:(CALayer *)layer above:(CALayer *)sibling;- (void)replaceSublayer:(CALayer *)layer with:(CALayer *)layer2;

@property CATransform3D sublayerTransform;













































































CODE DEMOLayer Tree

LAYER TREE HIERARCHY












































































LAYER CONTENT & STYLE













































































LAYER CONTENT & STYLE• Manipulate a layer’s appearance through the style properties

or custom drawing

• Custom drawing is accomplished one of three ways (from easiest to hardest):

• Set the contents property to a CGImageRef

• Set a delegate and implement the drawing method(s)

• Subclass CALayer















































































Content Properties@property(retain) id contents;

@property CGRect contentsRect;

@property(copy) NSString *contentsGravity;

@property CGRect contentsCenter;

@property(getter=isOpaque) BOOL opaque;

@property BOOL needsDisplayOnBoundsChange;

Style Properties@property CGColorRef backgroundColor;

@property CGFloat cornerRadius;

@property CGFloat borderWidth;

@property CGColorRef borderColor;

@property float opacity;

@property(retain) CALayer *mask;

Content Methods- (void)display;

- (void)setNeedsDisplay;

- (void)setNeedsDisplayInRect:(CGRect)r;

- (BOOL)needsDisplay;

- (void)displayIfNeeded;

- (void)drawInContext:(CGContextRef)ctx;

Drawing Delegate Methods- (void)displayLayer:(CALayer *)layer;

- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx;













































































CODE DEMOSImage Content

Delegate DrawingStyle Properties













































































ANIMATION(FINALLY!)













































































ANIMATION IN ENGLISH


Move the box from the left position to the right position over 2 seconds distributing the interpolated values along a curve that slopes slowly at the beginning, quickly through the middle and slowly again at the end.












































































ANIMATION OVERVIEW• An animation is defined by the property it is animating, the time it

takes, and the pacing of the interpolation

• All animatable properties have a default implicit animation

• All animatable properties can be explicitly animated as well

• Animations do not effect underlying geometric and style properties, only the rendering (presentation) of the layer

• All animation classes descend from CAAnimation

• A CAAnimation notifies an optional delegate at the start and end of its animation













































































ANIMATION TIMING• The CAMediaTiming protocol is responsible for the duration

and repeating of animations

• An animation’s timing is defined relative to its parent layer’s timespace (controlled by the speed property)

• The fillMode property defines the animation’s behavior outside of its active duration

• The CAMediaTimingFunction describes the pacing of the animation as a cubic bezier curve













































































ANIMATION TIMING


Default Timing Functions












































































• Use CABasicAnimation to explicitly animate a layer property

• toValue: The final value of the property

• fromValue: The optional starting value

• byValue: Add byValue to the current value


One PropertyCABasicAnimation

CAKeyframeAnimation

n PropertiesCAAnimationGroup

Layer Tree ActionsCATransition

PROPERTY ANIMATION













































































CODE DEMOBasic Animation

PROPERTY ANIMATION












































































• Use CAAnimationGroup to group multiple property animations to be run concurrently on the same layer

• The delegate and removedOnCompletion properties of the animations are ignored

• The duration, fillMode and beginTime properties of the property animations offer fine grained control over each animation

• The durations of the animations are clipped to the duration of the group, not scaled.



CAKeyframeAnimation



ANIMATION GROUPS













































































CODE DEMOAnimation Groups

ANIMATION GROUPS












































































• CAKeyframeAnimation allows more fine control over the animation of a layer property

• values: Array of toValues

• path: Animate along a CGPathRef (alt. to values)

• calculationMode: Interpolation style between keyframes



CAKeyframeAnimation



KEYFRAME ANIMATION













































































CODE DEMOKeyframe Animation

KEYFRAME ANIMATION












































































TRANSITIONS• A CATransition animates changes to the

layer tree

• Canned animations that effect an entire layer

• The type and subtype properties define the canned transition animation

• The CATransition is added to the parent layer and animates the hiding, showing, adding and removing of its child layers



CAKeyframeAnimation















































































CODE DEMOLayer Transitions

TRANSITIONS












































































ACTIONS & TRANSACTIONS


• A CATransaction groups changes to the layer tree into a single atomic update to the display

• Useful for temporarily disabling default layer actions

• Each step of the runloop opens and closes a CATransaction

• Layer actions are animations that are triggered by a change to an animatable layer property or the layer tree

• The implicit property animations are implemented as layer actions

CALayerDelegate Method to Select an Action- (id<CAAction>)actionForLayer:(CALayer *)layer forKey:(NSString *)event;













































































CODE DEMOSAnimation Transactions

Layer Actions

ACTIONS & TRANSACTIONS












































































SPECIAL LAYER TYPES













































































SPECIAL LAYER TYPES• CAScrollLayer: CALayer subclass for scrollable content

• CATiledLayer: For displaying very large layers (bigger than 1024x1024) at multiple levels of detail

• CAShapeLayer: Draws an animatable CGPath in its coordinate space (new in 3.0)

• CAGradientLayer: Draws a color gradient over its background color (new in 3.0)

• CATransformLayer: A container layer used to create a true 3D layer hierarchy (new in 3.0)

• CAReplicatorLayer: Creates copies of its sublayers with each copy potentially having geometric, temporal and color transformations applied to it














































































CODE DEMOSSpecial Layer Types

Miscellaneous Tips & Tricks

SPECIAL LAYER TYPES













































































THANK YOUNathan Eror

[email protected]

http://twitter.com/freetimestudios

http://www.freetimestudios.com

http://twitter.com/neror

http://www.neror.com












































































mailto:[email protected]

mailto:[email protected]











Documents

CORE ANIMATION: HANDS-ON...GEOMETRY & TRANSFORMS • 2D cartesian coordinate system with origin in the top left • Quartz2D primitive data structures (CGPoint, CGRect, etc.) • Each