core/java/android/view/transition/Recolor.java

/*
 * 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 android.view.transition;

import android.animation.Animator;
import android.animation.ArgbEvaluator;
import android.animation.ObjectAnimator;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.util.ArrayMap;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.Map;

/**
 * This transition tracks changes during scene changes to the
 * {@link View#setBackground(android.graphics.drawable.Drawable) background}
 * property of its target views (when the background is a
 * {@link ColorDrawable}, as well as the
 * {@link TextView#setTextColor(android.content.res.ColorStateList)
 * color} of the text for target TextViews. If the color changes between
 * scenes, the color change is animated.
 */
public class Recolor extends Transition {

    private static final String PROPNAME_BACKGROUND = "android:recolor:background";
    private static final String PROPNAME_TEXT_COLOR = "android:recolor:textColor";

    @Override
    protected void captureValues(TransitionValues values, boolean start) {
        values.values.put(PROPNAME_BACKGROUND, values.view.getBackground());
        if (values.view instanceof TextView) {
            values.values.put(PROPNAME_TEXT_COLOR, ((TextView)values.view).getCurrentTextColor());
        }
    }

    @Override
    protected Animator play(ViewGroup sceneRoot, TransitionValues startValues,
            TransitionValues endValues) {
        if (startValues == null || endValues == null) {
            return null;
        }
        final View view = endValues.view;
        Drawable startBackground = (Drawable) startValues.values.get(PROPNAME_BACKGROUND);
        Drawable endBackground = (Drawable) endValues.values.get(PROPNAME_BACKGROUND);
        boolean changed = false;
        if (startBackground instanceof ColorDrawable && endBackground instanceof ColorDrawable) {
            ColorDrawable startColor = (ColorDrawable) startBackground;
            ColorDrawable endColor = (ColorDrawable) endBackground;
            if (startColor.getColor() != endColor.getColor()) {
                endColor.setColor(startColor.getColor());
                changed = true;
                return ObjectAnimator.ofObject(endBackground, "color",
                        new ArgbEvaluator(), startColor.getColor(), endColor.getColor());
            }
        }
        if (view instanceof TextView) {
            TextView textView = (TextView) view;
            int start = (Integer) startValues.values.get(PROPNAME_TEXT_COLOR);
            int end = (Integer) endValues.values.get(PROPNAME_TEXT_COLOR);
            if (start != end) {
                textView.setTextColor(end);
                changed = true;
                return ObjectAnimator.ofObject(textView, "textColor",
                        new ArgbEvaluator(), start, end);
            }
        }
        return null;
    }
}