/*
* Copyright (C) 2009 Muthu Ramadoss. All rights reserved.
*
* Modified from Romain Guy Shelves project to suit Books-Exchange requirements.
* Original source from Shelves - http://code.google.com/p/shelves/
*/
/*
* Copyright (C) 2008 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.androidrocks.bex.drawable;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.os.SystemClock;
public class TransitionDrawable extends LayerDrawable implements Drawable.Callback {
/**
* 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 boolean mReverse;
private long mStartTimeMillis;
private int mFrom;
private int mTo;
private int mDuration;
private TransitionState mState;
public TransitionDrawable(Drawable... layers) {
this(new TransitionState(null, null), layers);
}
TransitionDrawable() {
this(new TransitionState(null, null));
}
private TransitionDrawable(TransitionState state) {
super(state);
mState = state;
}
private TransitionDrawable(TransitionState state, Drawable... layers) {
super(state, layers);
mState = state;
}
@Override
LayerState createConstantState(LayerState state) {
return new TransitionState((TransitionState) state, this);
}
/**
* 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;
mState.mAlpha = 0;
mState.mDuration = mDuration = durationMillis;
mReverse = false;
mTransitionState = TRANSITION_STARTING;
invalidateSelf();
}
/**
* Show only the first layer.
*/
public void resetTransition() {
mState.mAlpha = 0;
mTransitionState = TRANSITION_NONE;
invalidateSelf();
}
/**
* Reverses the transition, picking up where the transition currently is.
* If the transition is not currently running, this will start the transition
* with the specified duration. If the transition is already running, the last
* known duration will be used.
*
* @param duration The duration to use if no transition is running.
*/
public void reverseTransition(int duration) {
final long time = SystemClock.uptimeMillis();
// Animation is over
if (time - mStartTimeMillis > mState.mDuration) {
if (mState.mAlpha == 0) {
mFrom = 0;
mTo = 255;
mState.mAlpha = 0;
mReverse = false;
} else {
mFrom = 255;
mTo = 0;
mState.mAlpha = 255;
mReverse = true;
}
mDuration = mState.mDuration = duration;
mTransitionState = TRANSITION_STARTING;
invalidateSelf();
return;
}
mReverse = !mReverse;
mFrom = mState.mAlpha;
mTo = mReverse ? 0 : 255;
mDuration = (int) (mReverse ? time - mStartTimeMillis :
mState.mDuration - (time - mStartTimeMillis));
mTransitionState = TRANSITION_STARTING;
}
@Override
public void draw(Canvas canvas) {
boolean done = true;
final TransitionState state = mState;
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);
state.mAlpha = (int) (mFrom + (mTo - mFrom) * normalized);
}
break;
}
final int alpha = state.mAlpha;
final boolean crossFade = state.mCrossFade;
final Rec[] array = mLayerState.mArray;
Drawable d;
d = array[0].mDrawable;
if (crossFade) {
d.setAlpha(255 - alpha);
}
d.draw(canvas);
if (crossFade) {
d.setAlpha(0xFF);
}
if (alpha > 0) {
d = array[1].mDrawable;
d.setAlpha(alpha);
d.draw(canvas);
d.setAlpha(0xFF);
}
if (!done) {
invalidateSelf();
}
}
/**
* Enables or disables the cross fade of the drawables. When cross fade
* is disabled, the first drawable is always drawn opaque. With cross
* fade enabled, the first drawable is drawn with the opposite alpha of
* the second drawable.
*
* @param enabled True to enable cross fading, false otherwise.
*/
public void setCrossFadeEnabled(boolean enabled) {
mState.mCrossFade = enabled;
}
/**
* Indicates whether the cross fade is enabled for this transition.
*
* @return True if cross fading is enabled, false otherwise.
*/
public boolean isCrossFadeEnabled() {
return mState.mCrossFade;
}
static class TransitionState extends LayerState {
int mAlpha = 0;
int mDuration;
boolean mCrossFade;
TransitionState(TransitionState orig, TransitionDrawable owner) {
super(orig, owner);
}
@Override
public Drawable newDrawable() {
return new TransitionDrawable(this);
}
@Override
public int getChangingConfigurations() {
return mChangingConfigurations;
}
}
}