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/*
* Copyright (C) 2008 The Android Open Source Project
* Copyright (C) 2014 The Cyanogen, Inc
*
* 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.cyngn.theme.chooser;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.LayerDrawable;
import android.os.SystemClock;
/**
* An extension of LayerDrawables that is intended to cross-fade between
* the first and second layer. To start the transition, call {@link #startTransition(int)}. To
* display just the first layer, call {@link #resetTransition()}.
* <p>
* It can be defined in an XML file with the <code><transition></code> element.
* Each Drawable in the transition is defined in a nested <code><item></code>. For more
* information, see the guide to <a
* href="{@docRoot}guide/topics/resources/drawable-resource.html">Drawable Resources</a>.</p>
*
* @attr ref android.R.styleable#LayerDrawableItem_left
* @attr ref android.R.styleable#LayerDrawableItem_top
* @attr ref android.R.styleable#LayerDrawableItem_right
* @attr ref android.R.styleable#LayerDrawableItem_bottom
* @attr ref android.R.styleable#LayerDrawableItem_drawable
* @attr ref android.R.styleable#LayerDrawableItem_id
*
*/
public class IconTransitionDrawable extends LayerDrawable {
/**
* A transition is about to start.
*/
private static final int TRANSITION_STARTING = 0;
/**
* The transition has started and the animation is in progress
*/
private static final int TRANSITION_RUNNING = 1;
/**
* No transition will be applied
*/
private static final int TRANSITION_NONE = 2;
/**
* The current state of the transition. One of {@link #TRANSITION_STARTING},
* {@link #TRANSITION_RUNNING} and {@link #TRANSITION_NONE}
*/
private int mTransitionState = TRANSITION_NONE;
private long mStartTimeMillis;
private int mFrom;
private int mTo;
private int mDuration;
private int mAlpha = 0;
private float mFromScale;
private float mToScale;
/**
* Create a new transition drawable with the specified list of layers. At least
* 2 layers are required for this drawable to work properly.
*/
public IconTransitionDrawable(Drawable[] layers) {
super(layers);
}
/**
* Begin the second layer on top of the first layer.
*
* @param durationMillis The length of the transition in milliseconds
*/
public void startTransition(int durationMillis) {
mFrom = 0;
mTo = 255;
mAlpha = 0;
mFromScale = 0f;
mToScale = 1.0f;
mDuration = durationMillis;
mTransitionState = TRANSITION_STARTING;
invalidateSelf();
}
/**
* Show only the first layer.
*/
public void resetTransition() {
mAlpha = 0;
mTransitionState = TRANSITION_NONE;
invalidateSelf();
}
@Override
public void draw(Canvas canvas) {
boolean done = true;
float scale = 0f;
switch (mTransitionState) {
case TRANSITION_STARTING:
mStartTimeMillis = SystemClock.uptimeMillis();
done = false;
mTransitionState = TRANSITION_RUNNING;
break;
case TRANSITION_RUNNING:
if (mStartTimeMillis >= 0) {
float normalized = (float)
(SystemClock.uptimeMillis() - mStartTimeMillis) / mDuration;
done = normalized >= 1.0f;
normalized = Math.min(normalized, 1.0f);
mAlpha = (int) (mFrom + (mTo - mFrom) * normalized);
scale = mFromScale + (mToScale - mFromScale) * normalized;
}
break;
}
final int alpha = mAlpha;
if (done) {
// the setAlpha() calls below trigger invalidation and redraw. If we're done, just draw
// the appropriate drawable[s] and return
if (alpha == 0) {
getDrawable(0).draw(canvas);
}
if (alpha == 0xFF) {
getDrawable(1).draw(canvas);
}
return;
}
Drawable d;
d = getDrawable(0);
d.setAlpha(255 - alpha);
int cx = getIntrinsicWidth() / 2;
int cy = getIntrinsicHeight() / 2;
canvas.save();
canvas.scale(1.0f - scale, 1.0f - scale, cx, cy);
d.draw(canvas);
canvas.restore();
d.setAlpha(0xFF);
if (alpha > 0) {
d = getDrawable(1);
d.setAlpha(alpha);
canvas.save();
canvas.scale(scale, scale, cx, cy);
d.draw(canvas);
canvas.restore();
d.setAlpha(0xFF);
}
if (!done) {
invalidateSelf();
}
}
}
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