Ink

Ink

The Ink component provides a radial action in the form of a visual ripple expanding outward from the user's touch.

Design & API documentation

• Class: MDCInkGestureRecognizer
• Class: MDCInkTouchController
• Class: MDCInkView
• Protocol: MDCInkTouchControllerDelegate
• Protocol: MDCInkViewDelegate
• Enumeration: MDCInkStyle

Table of contents

• Overview
• Installation
  • Installation with CocoaPods
  • Importing
• Usage
  • MDCInkTouchController
  • MDCInkView
• Migration guides
  • Migration guide: Ink to Ripple

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Overview

Ink is a material design implementation of touch feedback.

Installation

Installation with CocoaPods

Add the following to your Podfile:

pod 'MaterialComponents/Ink'

Then, run the following command:

pod install

Importing

To import the component:

Swift

import MaterialComponents.MaterialInk

Objective-C

#import "MaterialInk.h"

Usage

The Ink component exposes two interfaces that you can use to add material-like feedback to the user:

1. MDCInkView is a subclass of UIView that draws and animates ink ripples and can be placed anywhere in your view hierarchy.
2. MDCInkTouchController bundles an MDCInkView instance with a UITapGestureRecognizer instance to conveniently drive the ink ripples from the user's touches.

MDCInkTouchController

The simplest method of using ink in your views is to use a MDCInkTouchController:

Swift

let myButton = UIButton(type: .system)
myButton.setTitle("Tap Me", for: .normal)
let inkTouchController = MDCInkTouchController(view: myButton)
inkTouchController.addInkView()

Objective-C

UIButton *myButton = [UIButton buttonWithType:UIButtonTypeSystem];
[myButton setTitle:@"Tap me" forState:UIControlStateNormal];
MDCInkTouchController *inkTouchController = [[MDCInkTouchController alloc] initWithView:myButton];
[inkTouchController addInkView];

The MDCInkTouchControllerDelegate gives you control over aspects of the ink/touch relationship, such as how the ink view is created, where it is inserted in view hierarchy, etc. For example, to temporarily disable ink touches, the following code uses the delegate's inkTouchController:shouldProcessInkTouchesAtTouchLocation: method:

Swift

class MyDelegate: NSObject, MDCInkTouchControllerDelegate {

  func inkTouchController(_ inkTouchController: MDCInkTouchController, shouldProcessInkTouchesAtTouchLocation location: CGPoint) -> Bool {
    // Determine if we want to display the ink
    return true
  }

}

...

let myButton = UIButton(type: .system)
myButton.setTitle("Tap Me", for: .normal)

let myDelegate = MyDelegate()

let inkTouchController = MDCInkTouchController(view: myButton)
inkTouchController.delegate = myDelegate
inkTouchController.addInkView()

Objective-C

@interface MyDelegate: NSObject <MDCInkTouchControllerDelegate>
@end

@implementation MyDelegate

- (BOOL)inkTouchController:(MDCInkTouchController *)inkTouchController
    shouldProcessInkTouchesAtTouchLocation:(CGPoint)location {
  return YES;
}

@end

...

UIButton *myButton = [UIButton buttonWithType:UIButtonTypeSystem];
[myButton setTitle:@"Tap me" forState:UIControlStateNormal];
MyDelegate *myDelegate = [[MyDelegate alloc] init];
MDCInkTouchController *inkTouchController = [[MDCInkTouchController alloc] initWithView:myButton];
inkTouchController.delegate = myDelegate;
[inkTouchController addInkView];

NOTE: The ink touch controller does not keep a strong reference to the view to which it is attaching the ink view. An easy way to prevent the ink touch controller from being deallocated prematurely is to make it a property of a view controller (like in these examples.)

MDCInkView

Alternatively, you can use MCDInkView directly to display ink ripples using your own touch processing:

Swift

let myCustomView = MyCustomView(frame: CGRect.zero)
let inkView = MDCInkView()
inkView.inkColor = UIColor.red
myCustomView.addSubview(inkView)
...
// When the touches begin, there is one animation
inkView.startTouchBeganAnimation(at: touchPoint, completion: nil)
...
// When the touches end, there is another animation
inkView.startTouchEndedAnimation(at: touchPoint, completion: nil)

Objective-C

MyCustomView *myCustomView = [[MyCustomView alloc] initWithFrame:CGRectZero];
MDCInkView *inkView = [[MDCInkView alloc] init];
inkView.inkColor = [UIColor redColor];
[myCustomView addSubview:inkView];
...
// When the touches begin, there is one animation
[inkView startTouchBeganAnimationAtPoint:touchPoint completion:nil];
...
// When the touches end, there is another animation
[inkView startTouchEndedAnimationAtPoint:touchPoint completion:nil];

Migration guides

Migration guide: Ink to Ripple

Ink and Ripple provide similar APIs: a view (MDCInkView, MDCRippleView), and a touch controller (MDCInkTouchController, MDCRippleTouchController).

While Ripple and Ink’s implementations slightly vary, the public APIs are nearly identical. Furthermore, Ripple’s API does not produce additional side effects and can be used interchangeably.

These two notions make the migration path from Ink to Ripple relatively simple.

For guidance, these are the current naming differences that you need to pay attention to when migrating:

MDCInkView vs MDCRippleView:

MDCInkView	MDCRippleView
animationDelegate	rippleViewDelegate
maxRippleRadius	maximumRadius
startTouchBeganAtPoint:animated:completion:	beginRippleTouchDownAtPoint:animated:completion:
startTouchEndAtPoint:animated:completion:	beginRippleTouchUpAnimated:completion:
inkAnimationDidStart:inkView	rippleTouchDownAnimationDidBegin:rippleView
inkAnimationDidEnd:inkView	rippleTouchUpAnimationDidEnd:rippleView
inkStyle	rippleStyle
inkColor	rippleColor
cancelAllAnimationsAnimated:	cancelAllRipplesAnimated:completion:

MDCInkTouchController vs MDCRippleTouchController:

MDCInkTouchController	MDCRippleTouchController
defaultInkView	rippleView
initWithView: → addInkView	init → addRippleToView:*
view	view
delegate	delegate
gestureRecognizer	gestureRecognizer
inkTouchController:insertInkView:intoView:	rippleTouchController:insertRippleView:intoView:
inkTouchController:shouldProcessInkTouchesAtTouchLocation:	rippleTouchController:shouldProcessRippleTouchesAtTouchLocation:
inkTouchController:didProcessInkTouchesAtTouchLocation:	rippleTouchController:didProcessRippleTouchesAtTouchLocation:

*Ripple provides a more convenient API if the ink's initialized view is the view that the ink is then added to. All you need is to initialize the ripple with initWithView: and there is no need to use an equivalent addInkView afterwards.

Based on the above guidance, the overall strategy to migrate Ink to Ripple in each component is as follows:

• Provide an enableRippleBehavior bool property to allow to opt-in to use Ripple instead of Ink (where the default to this property is NO).

Component Header:

/*
 This property determines if an @c <#INSERT CLASS NAME> should use the @c MDCRippleView behavior or not.
 By setting this property to @c YES, @c MDCRippleView is used to provide the user visual
 touch feedback, instead of the legacy @c MDCInkView.
 @note Defaults to @c NO.
 */
@property(nonatomic, assign) BOOL enableRippleBehavior;

Component Implementation Setter:

- (void)setEnableRippleBehavior:(BOOL)enableRippleBehavior {
  _enableRippleBehavior = enableRippleBehavior;

  if (enableRippleBehavior) {
    [self.inkView removeFromSuperview];
    self.rippleView.frame = self.bounds;
    [self insertSubview:self.rippleView belowSubview:X];
  } else {
    [self.rippleView removeFromSuperview];
    [self insertSubview:self.inkView belowSubview:X];
  }
}

• Add the RippleView/RippleTouchController APIs beside their InkView/InkTouchController counterparts.

• If the component itself has public APIs that use the term "Ink" like “InkStyle” or “InkColor”, the developer should add APIs to use the term “Ripple” instead. When Ink will eventually be deprecated, these APIs will be deprecated as part of that process. Another option instead of exposing specific Ripple APIs is to expose the `MDCRippleView` property in the public API.