1 /* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.example.android.curvedmotion; 18 19 import android.animation.ObjectAnimator; 20 import android.app.Activity; 21 import android.os.Bundle; 22 import android.view.View; 23 import android.view.ViewTreeObserver; 24 import android.view.animation.DecelerateInterpolator; 25 import android.widget.Button; 26 import android.widget.RelativeLayout; 27 import android.widget.RelativeLayout.LayoutParams; 28 29 /** 30 * This app shows how to move a view in a curved path between two endpoints. 31 * The real work is done by PathEvaluator, which interpolates along a path 32 * using Bezier control and anchor points in the path. 33 * 34 * Watch the associated video for this demo on the DevBytes channel of developer.android.com 35 * or on the DevBytes playlist in the androiddevelopers channel on YouTube at 36 * https://www.youtube.com/playlist?list=PLWz5rJ2EKKc_XOgcRukSoKKjewFJZrKV0. 37 */ 38 public class CurvedMotion extends Activity { 39 40 private static final DecelerateInterpolator sDecelerateInterpolator = 41 new DecelerateInterpolator(); 42 boolean mTopLeft = true; 43 Button mButton; 44 45 @Override onCreate(Bundle savedInstanceState)46 protected void onCreate(Bundle savedInstanceState) { 47 super.onCreate(savedInstanceState); 48 setContentView(R.layout.activity_curved_motion); 49 50 mButton = (Button) findViewById(R.id.button); 51 mButton.setOnClickListener(new View.OnClickListener() { 52 53 @Override 54 public void onClick(View v) { 55 // Capture current location of button 56 final int oldLeft = mButton.getLeft(); 57 final int oldTop = mButton.getTop(); 58 59 // Change layout parameters of button to move it 60 moveButton(); 61 62 // Add OnPreDrawListener to catch button after layout but before drawing 63 mButton.getViewTreeObserver().addOnPreDrawListener( 64 new ViewTreeObserver.OnPreDrawListener() { 65 public boolean onPreDraw() { 66 mButton.getViewTreeObserver().removeOnPreDrawListener(this); 67 68 // Capture new location 69 int left = mButton.getLeft(); 70 int top = mButton.getTop(); 71 int deltaX = left - oldLeft; 72 int deltaY = top - oldTop; 73 74 // Set up path to new location using a B�zier spline curve 75 AnimatorPath path = new AnimatorPath(); 76 path.moveTo(-deltaX, -deltaY); 77 path.curveTo(-(deltaX/2), -deltaY, 0, -deltaY/2, 0, 0); 78 79 // Set up the animation 80 final ObjectAnimator anim = ObjectAnimator.ofObject( 81 CurvedMotion.this, "buttonLoc", 82 new PathEvaluator(), path.getPoints().toArray()); 83 anim.setInterpolator(sDecelerateInterpolator); 84 anim.start(); 85 return true; 86 } 87 }); 88 } 89 }); 90 } 91 92 /** 93 * Toggles button location on click between top-left and bottom-right 94 */ moveButton()95 private void moveButton() { 96 LayoutParams params = (LayoutParams) mButton.getLayoutParams(); 97 if (mTopLeft) { 98 params.removeRule(RelativeLayout.ALIGN_PARENT_LEFT); 99 params.removeRule(RelativeLayout.ALIGN_PARENT_TOP); 100 params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT); 101 params.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM); 102 } else { 103 params.addRule(RelativeLayout.ALIGN_PARENT_LEFT); 104 params.addRule(RelativeLayout.ALIGN_PARENT_TOP); 105 params.removeRule(RelativeLayout.ALIGN_PARENT_RIGHT); 106 params.removeRule(RelativeLayout.ALIGN_PARENT_BOTTOM); 107 } 108 mButton.setLayoutParams(params); 109 mTopLeft = !mTopLeft; 110 } 111 112 /** 113 * We need this setter to translate between the information the animator 114 * produces (a new "PathPoint" describing the current animated location) 115 * and the information that the button requires (an xy location). The 116 * setter will be called by the ObjectAnimator given the 'buttonLoc' 117 * property string. 118 */ setButtonLoc(PathPoint newLoc)119 public void setButtonLoc(PathPoint newLoc) { 120 mButton.setTranslationX(newLoc.mX); 121 mButton.setTranslationY(newLoc.mY); 122 } 123 124 } 125