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/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.android.curvedmotion;
import android.animation.ObjectAnimator;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewTreeObserver;
import android.view.animation.DecelerateInterpolator;
import android.widget.Button;
import android.widget.RelativeLayout;
import android.widget.RelativeLayout.LayoutParams;
/**
* This app shows how to move a view in a curved path between two endpoints.
* The real work is done by PathEvaluator, which interpolates along a path
* using Bezier control and anchor points in the path.
*
* Watch the associated video for this demo on the DevBytes channel of developer.android.com
* or on the DevBytes playlist in the androiddevelopers channel on YouTube at
* https://www.youtube.com/playlist?list=PLWz5rJ2EKKc_XOgcRukSoKKjewFJZrKV0.
*/
public class CurvedMotion extends Activity {
private static final DecelerateInterpolator sDecelerateInterpolator =
new DecelerateInterpolator();
boolean mTopLeft = true;
Button mButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_curved_motion);
mButton = (Button) findViewById(R.id.button);
mButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// Capture current location of button
final int oldLeft = mButton.getLeft();
final int oldTop = mButton.getTop();
// Change layout parameters of button to move it
moveButton();
// Add OnPreDrawListener to catch button after layout but before drawing
mButton.getViewTreeObserver().addOnPreDrawListener(
new ViewTreeObserver.OnPreDrawListener() {
public boolean onPreDraw() {
mButton.getViewTreeObserver().removeOnPreDrawListener(this);
// Capture new location
int left = mButton.getLeft();
int top = mButton.getTop();
int deltaX = left - oldLeft;
int deltaY = top - oldTop;
// Set up path to new location using a B�zier spline curve
AnimatorPath path = new AnimatorPath();
path.moveTo(-deltaX, -deltaY);
path.curveTo(-(deltaX/2), -deltaY, 0, -deltaY/2, 0, 0);
// Set up the animation
final ObjectAnimator anim = ObjectAnimator.ofObject(
CurvedMotion.this, "buttonLoc",
new PathEvaluator(), path.getPoints().toArray());
anim.setInterpolator(sDecelerateInterpolator);
anim.start();
return true;
}
});
}
});
}
/**
* Toggles button location on click between top-left and bottom-right
*/
private void moveButton() {
LayoutParams params = (LayoutParams) mButton.getLayoutParams();
if (mTopLeft) {
params.removeRule(RelativeLayout.ALIGN_PARENT_LEFT);
params.removeRule(RelativeLayout.ALIGN_PARENT_TOP);
params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
params.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
} else {
params.addRule(RelativeLayout.ALIGN_PARENT_LEFT);
params.addRule(RelativeLayout.ALIGN_PARENT_TOP);
params.removeRule(RelativeLayout.ALIGN_PARENT_RIGHT);
params.removeRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
}
mButton.setLayoutParams(params);
mTopLeft = !mTopLeft;
}
/**
* We need this setter to translate between the information the animator
* produces (a new "PathPoint" describing the current animated location)
* and the information that the button requires (an xy location). The
* setter will be called by the ObjectAnimator given the 'buttonLoc'
* property string.
*/
public void setButtonLoc(PathPoint newLoc) {
mButton.setTranslationX(newLoc.mX);
mButton.setTranslationY(newLoc.mY);
}
}
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