/*
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* Copyright (C) 2008 The Android Open Source Project, Romain Guy
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* Copyright (C) 2008 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.lcjian.library.drawable;
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import android.graphics.Canvas;
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import android.graphics.drawable.Drawable;
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import android.os.SystemClock;
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public class TransitionDrawable extends LayerDrawable implements Drawable.Callback {
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/**
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* A transition is about to start.
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*/
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private static final int TRANSITION_STARTING = 0;
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/**
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* The transition has started and the animation is in progress
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*/
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private static final int TRANSITION_RUNNING = 1;
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/**
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* No transition will be applied
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*/
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private static final int TRANSITION_NONE = 2;
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/**
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* The current state of the transition. One of {@link #TRANSITION_STARTING},
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* {@link #TRANSITION_RUNNING} and {@link #TRANSITION_NONE}
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*/
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private int mTransitionState = TRANSITION_NONE;
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private boolean mReverse;
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private long mStartTimeMillis;
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private int mFrom;
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private int mTo;
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private int mDuration;
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private TransitionState mState;
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public TransitionDrawable(Drawable... layers) {
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this(new TransitionState(null, null), layers);
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}
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TransitionDrawable() {
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this(new TransitionState(null, null));
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}
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private TransitionDrawable(TransitionState state) {
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super(state);
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mState = state;
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}
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private TransitionDrawable(TransitionState state, Drawable... layers) {
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super(state, layers);
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mState = state;
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}
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@Override
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LayerState createConstantState(LayerState state) {
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return new TransitionState((TransitionState) state, this);
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}
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/**
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* Begin the second layer on top of the first layer.
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*
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* @param durationMillis The length of the transition in milliseconds
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*/
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public void startTransition(int durationMillis) {
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mFrom = 0;
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mTo = 255;
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mState.mAlpha = 0;
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mState.mDuration = mDuration = durationMillis;
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mReverse = false;
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mTransitionState = TRANSITION_STARTING;
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invalidateSelf();
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}
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/**
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* Show only the first layer.
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*/
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public void resetTransition() {
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mState.mAlpha = 0;
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mTransitionState = TRANSITION_NONE;
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invalidateSelf();
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}
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/**
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* Reverses the transition, picking up where the transition currently is.
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* If the transition is not currently running, this will start the transition
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* with the specified duration. If the transition is already running, the last
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* known duration will be used.
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*
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* @param duration The duration to use if no transition is running.
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*/
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public void reverseTransition(int duration) {
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final long time = SystemClock.uptimeMillis();
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// Animation is over
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if (time - mStartTimeMillis > mState.mDuration) {
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if (mState.mAlpha == 0) {
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mFrom = 0;
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mTo = 255;
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mState.mAlpha = 0;
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mReverse = false;
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} else {
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mFrom = 255;
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mTo = 0;
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mState.mAlpha = 255;
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mReverse = true;
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}
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mDuration = mState.mDuration = duration;
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mTransitionState = TRANSITION_STARTING;
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invalidateSelf();
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return;
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}
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mReverse = !mReverse;
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mFrom = mState.mAlpha;
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mTo = mReverse ? 0 : 255;
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mDuration = (int) (mReverse ? time - mStartTimeMillis :
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mState.mDuration - (time - mStartTimeMillis));
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mTransitionState = TRANSITION_STARTING;
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}
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@Override
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public void draw(Canvas canvas) {
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boolean done = true;
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final TransitionState state = mState;
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switch (mTransitionState) {
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case TRANSITION_STARTING:
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mStartTimeMillis = SystemClock.uptimeMillis();
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done = false;
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mTransitionState = TRANSITION_RUNNING;
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break;
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case TRANSITION_RUNNING:
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if (mStartTimeMillis >= 0) {
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float normalized = (float)
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(SystemClock.uptimeMillis() - mStartTimeMillis) / mDuration;
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done = normalized >= 1.0f;
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normalized = Math.min(normalized, 1.0f);
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state.mAlpha = (int) (mFrom + (mTo - mFrom) * normalized);
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}
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break;
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}
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final int alpha = state.mAlpha;
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final boolean crossFade = state.mCrossFade;
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final Rec[] array = mLayerState.mArray;
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Drawable d;
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d = array[0].mDrawable;
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if (crossFade) {
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d.setAlpha(255 - alpha);
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}
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d.draw(canvas);
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if (crossFade) {
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d.setAlpha(0xFF);
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}
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if (alpha > 0) {
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d = array[1].mDrawable;
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d.setAlpha(alpha);
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d.draw(canvas);
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d.setAlpha(0xFF);
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}
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if (!done) {
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invalidateSelf();
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}
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}
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/**
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* Enables or disables the cross fade of the drawables. When cross fade
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* is disabled, the first drawable is always drawn opaque. With cross
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* fade enabled, the first drawable is drawn with the opposite alpha of
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* the second drawable.
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*
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* @param enabled True to enable cross fading, false otherwise.
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*/
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public void setCrossFadeEnabled(boolean enabled) {
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mState.mCrossFade = enabled;
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}
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/**
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* Indicates whether the cross fade is enabled for this transition.
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*
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* @return True if cross fading is enabled, false otherwise.
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*/
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public boolean isCrossFadeEnabled() {
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return mState.mCrossFade;
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}
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static class TransitionState extends LayerState {
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int mAlpha = 0;
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int mDuration;
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boolean mCrossFade;
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TransitionState(TransitionState orig, TransitionDrawable owner) {
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super(orig, owner);
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}
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@Override
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public Drawable newDrawable() {
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return new TransitionDrawable(this);
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}
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@Override
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public int getChangingConfigurations() {
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return mChangingConfigurations;
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}
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}
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}
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