Ripple

The Ripple component provides a radial action in the form of a visual ripple expanding outward from the user's touch. Ripple is a visual form of feedback for touch events providing users a clear signal that an element is being touched.

Design & API documentation

Table of contents

• Overview
• Installation
  • Installation with CocoaPods
  • Importing
• Usage
  • Importing
  • MDCRippleTouchController
  • MDCRippleView
  • MDCStatefulRippleView
• Migrations
  • usesSuperviewShadowLayerAsMask migration

Overview

Ripple is a material design implementation of touch feedback and is a successor of Ink.

Installation

Installation with CocoaPods

Add the following to your Podfile:

pod 'MaterialComponents/Ripple'

Then, run the following command:

pod install

Importing

To import the component:

Swift

import MaterialComponents.MaterialRipple

Objective-C

#import "MaterialRipple.h"

Usage

Importing

Before using Ripple, you'll need to import it:

Swift

import MaterialComponents.MaterialRipple

Objective-C

#import "MaterialRipple.h"

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

1. MDCRippleView is a subclass of UIView that draws and animates ripples and can be placed anywhere in your view hierarchy.
2. MDCRippleTouchController bundles an MDCRippleView instance with a UITapGestureRecognizer instance to conveniently drive the ripples from the user's touches.
3. MDCStatefulRippleView is a subclass of MDCRippleView that provides support for states. This allows to set the ripple in a state and have the ripple visually represent that state as part of the Material guidelines.

MDCRippleTouchController

The simplest method of using ripple in your views is to use a MDCRippleTouchController:

Initialize using the default initializer:

Swift

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

Objective-C

UIButton *myButton = [UIButton buttonWithType:UIButtonTypeSystem];
[myButton setTitle:@"Tap me" forState:UIControlStateNormal];
MDCRippleTouchController *rippleTouchController = [[MDCRippleTouchController alloc] init];
[rippleTouchController addRippleToView:myButton];

Initialize using the initWithView: convenience initializer:

Swift

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

Objective-C

UIButton *myButton = [UIButton buttonWithType:UIButtonTypeSystem];
[myButton setTitle:@"Tap me" forState:UIControlStateNormal];
MDCRippleTouchController *rippleTouchController = [[MDCRippleTouchController alloc] initWithView:myButton];

The MDCRippleTouchControllerDelegate gives you some control over aspects of the ripple/touch relationship and its placement in the view hierarchy. In the example below we are using the delegate to declare that we only want to process ripple touches if the touch is in a certain location. We also insert the Ripple view at the bottom of the parent view‘s view hierarchy. The reason we insert the ripple view at the bottom of the parent view’s hierarchy in this example, is so the ripple‘s overlay color would not affect the visibility and contrast of the view’s subviews, which may be images conveying a message or text.

Swift

class MyDelegate: NSObject, MDCRippleTouchControllerDelegate {

  func rippleTouchController(_ rippleTouchController: MDCRippleTouchController, shouldProcessRippleTouchesAtTouchLocation location: CGPoint) -> Bool {
    // Determine if we want to display the ripple
    return exampleView.frame.contains(location)
  }

  func rippleTouchController(_ rippleTouchController: MDCRippleTouchController,
                             insert rippleView: MDCRippleView,
                             into view: UIView) {
    view.insertSubview(rippleView, at: 0)
  }

  func rippleTouchController(_ rippleTouchController: MDCRippleTouchController,
                             didProcessRippleView rippleView: MDCRippleView,
                             atTouchLocation location: CGPoint) {
    print("Did process ripple view!")
  }

}

...

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

let myDelegate = MyDelegate()

let rippleTouchController = MDCRippleTouchController(view: myButton)
rippleTouchController.delegate = myDelegate

Objective-C

@interface MyDelegate: NSObject <MDCRippleTouchControllerDelegate>
@end

@implementation MyDelegate

- (BOOL)rippleTouchController:(MDCRippleTouchController *)rippleTouchController
    shouldProcessRippleTouchesAtTouchLocation:(CGPoint)location {
  return CGRectContainsPoint(exampleView.frame, location);
}

- (void)rippleTouchController:(MDCRippleTouchController *)rippleTouchController
         didProcessRippleView:(MDCRippleView *)rippleView
              atTouchLocation:(CGPoint)location {
  NSLog(@"Did process ripple view!");
}

- (void)rippleTouchController:(MDCRippleTouchController *)rippleTouchController insertRippleView:(MDCRippleView *)rippleView intoView:(UIView *)view {
    [view insertSubview:rippleView atIndex:0];
}
@end

...

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

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

MDCRippleView

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

Swift

let myCustomView = MyCustomView(frame: .zero)
let rippleView = MDCRippleView()
rippleView.rippleColor = .red
myCustomView.addSubview(rippleView)
...
// When the touches begin, there is one animation
rippleView.beginRippleTouchDownAtPoint(at: touchPoint, animated: true, completion: nil)
...
// When the touches end, there is another animation
rippleView.beginRippleTouchUpAnimated(animated: true, completion: nil)

Objective-C

MyCustomView *myCustomView = [[MyCustomView alloc] initWithFrame:CGRectZero];
MDCRippleView *rippleView = [[MDCRippleView alloc] init];
rippleView.rippleColor = UIColor.redColor;
[myCustomView addSubview:rippleView];
...
// When the touches begin, there is one animation
[rippleView beginRippleTouchDownAtPoint:touchPoint animated:YES completion:nil];
...
// When the touches end, there is another animation
[rippleView beginRippleTouchUpAnimated:YES completion:nil];

MDCStatefulRippleView

You can also use MDCStatefulRippleView to display stateful ripples using your own touch processing. To fully benefit from MDCStatefulRipple‘s ability to move between states visually, the view that is adding the stateful ripple view must override UIView’s touchesBegan, touchesMoved, touchesEnded and touchesCancelled and call the stateful ripple view's corresponding APIs before calling the super implementation. Here is an example:

Swift

let myCustomView = MyCustomView(frame: .zero)
let statefulRippleView = MDCStatefulRippleView()
statefulRippleView.setRippleColor(.blue, for: .selected)
myCustomView.addSubview(statefulRippleView)

...

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
  statefulRippleView.touchesBegan(touches, with: event)
  super.touchesBegan(touches, with: event)

  statefulRippleView.isRippleHighlighted = true
}

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
  statefulRippleView.touchesMoved(touches, with: event)
  super.touchesMoved(touches, with: event)
}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
  statefulRippleView.touchesEnded(touches, with: event)
  super.touchesEnded(touches, with: event)

  statefulRippleView.isRippleHighlighted = false
}

override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
  statefulRippleView.touchesCancelled(touches, with: event)
  super.touchesCancelled(touches, with: event)

  statefulRippleView.isRippleHighlighted = false
}

Objective-C

MyCustomView *myCustomView = [[MyCustomView alloc] initWithFrame:CGRectZero];
MDCStatefulRippleView *statefulRippleView = [[MDCStatefulRippleView alloc] init];
[statefulRippleView setRippleColor:UIColor.blueColor forState:MDCRippleStateSelected];
[myCustomView addSubview:statefulRippleView];

...

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
  [statefulRippleView touchesBegan:touches withEvent:event];
  [super touchesBegan:touches withEvent:event];

  statefulRippleView.rippleHighlighted = YES;
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
  [statefulRippleView touchesMoved:touches withEvent:event];
  [super touchesMoved:touches withEvent:event];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
  [statefulRippleView touchesEnded:touches withEvent:event];
  [super touchesEnded:touches withEvent:event];

  statefulRippleView.rippleHighlighted = NO;
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
  [statefulRippleView touchesCancelled:touches withEvent:event];
  [super touchesCancelled:touches withEvent:event];

  statefulRippleView.rippleHighlighted = NO;
}

Migrations

usesSuperviewShadowLayerAsMask migration

tl;dr: If you are adding ripples to views with custom layer.shadowPath values, please disable usesSuperviewShadowLayerAsMask and assign an explicit layer mask to the ripple view if needed instead. usesSuperviewShadowLayerAsMask will eventually be disabled by default and then deleted.

MDCRippleView currently implements a convenience behavior that will inherit its parent view‘s layer.shadowPath as the mask of the ripple view itself. This works for the general case where the ripple view’s frame equals the bounds of its super view, but behaves unexpectedly for any other frame of the ripple view.

Due to the brittleness of this behavior, a new migration property, usesSuperviewShadowLayerAsMask, has been added that will allow you to disable this behavior in favor of a more explicit determination of the ripple's layer mask.

Example usage:

Swift

// During initialization:
rippleView.usesSuperviewShadowLayerAsMask = false

// Simple example of applying a mask to the ripple view using the ripple view's bounds:
let rippleViewMask = CAShapeLayer()
rippleViewMask.path = UIBezierPath(rect: rippleView.bounds).cgPath
rippleView.layer.mask = rippleViewMask

Objective-C

// During initialization:
rippleView.usesSuperviewShadowLayerAsMask = NO;

// Simple example of applying a mask to the ripple view using the ripple view's bounds:
CAShapeLayer *rippleViewMask = [[CAShapeLayer alloc] init];
rippleViewMask.path = [UIBezierPath bezierPathWithRect:rippleView.bounds].CGPath;
rippleView.layer.mask = rippleViewMask;

Please consider disabling usesSuperviewShadowLayerAsMask if you are creating MDCRippleView instances. The property will be disabled by default in the future and then deprecated.