android/support/design/internal/TextScale.java

/*
 * Copyright (C) 2016 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.support.design.internal;

import android.animation.Animator;
import android.animation.ValueAnimator;
import android.support.annotation.RequiresApi;
import android.support.annotation.RestrictTo;
import android.support.transition.Transition;
import android.support.transition.TransitionValues;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.Map;

/**
 * @hide
 */
@RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
@RequiresApi(14)
public class TextScale extends Transition {
    private static final String PROPNAME_SCALE = "android:textscale:scale";

    @Override
    public void captureStartValues(TransitionValues transitionValues) {
        captureValues(transitionValues);
    }

    @Override
    public void captureEndValues(TransitionValues transitionValues) {
        captureValues(transitionValues);
    }

    private void captureValues(TransitionValues transitionValues) {
        if (transitionValues.view instanceof TextView) {
            TextView textview = (TextView) transitionValues.view;
            transitionValues.values.put(PROPNAME_SCALE, textview.getScaleX());
        }
    }

    @Override
    public Animator createAnimator(ViewGroup sceneRoot, TransitionValues startValues,
            TransitionValues endValues) {
        if (startValues == null || endValues == null || !(startValues.view instanceof TextView)
                || !(endValues.view instanceof TextView)) {
            return null;
        }
        final TextView view = (TextView) endValues.view;
        Map<String, Object> startVals = startValues.values;
        Map<String, Object> endVals = endValues.values;
        final float startSize = startVals.get(PROPNAME_SCALE) != null ? (float) startVals.get(
                PROPNAME_SCALE) : 1f;
        final float endSize = endVals.get(PROPNAME_SCALE) != null ? (float) endVals.get(
                PROPNAME_SCALE) : 1f;
        if (startSize == endSize) {
            return null;
        }

        ValueAnimator animator = ValueAnimator.ofFloat(startSize, endSize);

        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator valueAnimator) {
                float animatedValue = (float) valueAnimator.getAnimatedValue();
                view.setScaleX(animatedValue);
                view.setScaleY(animatedValue);
            }
        });
        return animator;
    }
}