/*
 * Copyright (C) 2014 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.transition;

import android.animation.Animator;
import android.animation.ObjectAnimator;
import android.animation.TypeEvaluator;
import android.content.Context;
import android.graphics.Matrix;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Property;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

import java.util.Map;

This Transition captures an ImageView's matrix before and after the
scene change and animates it during the transition.
In combination with ChangeBounds, ChangeImageTransform allows ImageViews that change size, shape, or ScaleType to animate contents smoothly.
/**
 * This Transition captures an ImageView's matrix before and after the
 * scene change and animates it during the transition.
 *
 * <p>In combination with ChangeBounds, ChangeImageTransform allows ImageViews
 * that change size, shape, or {@link android.widget.ImageView.ScaleType} to animate contents
 * smoothly.</p>
 */
public class ChangeImageTransform extends Transition {

    private static final String TAG = "ChangeImageTransform";

    private static final String PROPNAME_MATRIX = "android:changeImageTransform:matrix";
    private static final String PROPNAME_BOUNDS = "android:changeImageTransform:bounds";

    private static final String[] sTransitionProperties = {
            PROPNAME_MATRIX,
            PROPNAME_BOUNDS,
    };

    private static TypeEvaluator<Matrix> NULL_MATRIX_EVALUATOR = new TypeEvaluator<Matrix>() {
        @Override
        public Matrix evaluate(float fraction, Matrix startValue, Matrix endValue) {
            return null;
        }
    };

    private static Property<ImageView, Matrix> ANIMATED_TRANSFORM_PROPERTY
            = new Property<ImageView, Matrix>(Matrix.class, "animatedTransform") {
        @Override
        public void set(ImageView object, Matrix value) {
            object.animateTransform(value);
        }

        @Override
        public Matrix get(ImageView object) {
            return null;
        }
    };

    public ChangeImageTransform() {}

    public ChangeImageTransform(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    private void captureValues(TransitionValues transitionValues) {
        View view = transitionValues.view;
        if (!(view instanceof ImageView) || view.getVisibility() != View.VISIBLE) {
            return;
        }
        ImageView imageView = (ImageView) view;
        Drawable drawable = imageView.getDrawable();
        if (drawable == null) {
            return;
        }
        Map<String, Object> values = transitionValues.values;

        int left = view.getLeft();
        int top = view.getTop();
        int right = view.getRight();
        int bottom = view.getBottom();

        Rect bounds = new Rect(left, top, right, bottom);
        values.put(PROPNAME_BOUNDS, bounds);
        Matrix matrix;
        ImageView.ScaleType scaleType = imageView.getScaleType();
        if (scaleType == ImageView.ScaleType.FIT_XY) {
            matrix = imageView.getImageMatrix();
            if (!matrix.isIdentity()) {
                matrix = new Matrix(matrix);
            } else {
                int drawableWidth = drawable.getIntrinsicWidth();
                int drawableHeight = drawable.getIntrinsicHeight();
                if (drawableWidth > 0 && drawableHeight > 0) {
                    float scaleX = ((float) bounds.width()) / drawableWidth;
                    float scaleY = ((float) bounds.height()) / drawableHeight;
                    matrix = new Matrix();
                    matrix.setScale(scaleX, scaleY);
                } else {
                    matrix = null;
                }
            }
        } else {
            matrix = new Matrix(imageView.getImageMatrix());
        }
        values.put(PROPNAME_MATRIX, matrix);
    }

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

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

    @Override
    public String[] getTransitionProperties() {
        return sTransitionProperties;
    }

    
Creates an Animator for ImageViews moving, changing dimensions, and/or changing ScaleType. 
Params:
sceneRoot –   The root of the transition hierarchy.
startValues – The values for a specific target in the start scene.
endValues –   The values for the target in the end scene.
Returns:
An Animator to move an ImageView or null if the View is not an ImageView,
the Drawable changed, the View is not VISIBLE, or there was no change./**
     * Creates an Animator for ImageViews moving, changing dimensions, and/or changing
     * {@link android.widget.ImageView.ScaleType}.
     *
     * @param sceneRoot   The root of the transition hierarchy.
     * @param startValues The values for a specific target in the start scene.
     * @param endValues   The values for the target in the end scene.
     * @return An Animator to move an ImageView or null if the View is not an ImageView,
     * the Drawable changed, the View is not VISIBLE, or there was no change.
     */
    @Override
    public Animator createAnimator(ViewGroup sceneRoot, TransitionValues startValues,
            TransitionValues endValues) {
        if (startValues == null || endValues == null) {
            return null;
        }
        Rect startBounds = (Rect) startValues.values.get(PROPNAME_BOUNDS);
        Rect endBounds = (Rect) endValues.values.get(PROPNAME_BOUNDS);
        if (startBounds == null || endBounds == null) {
            return null;
        }

        Matrix startMatrix = (Matrix) startValues.values.get(PROPNAME_MATRIX);
        Matrix endMatrix = (Matrix) endValues.values.get(PROPNAME_MATRIX);

        boolean matricesEqual = (startMatrix == null && endMatrix == null) ||
                (startMatrix != null && startMatrix.equals(endMatrix));

        if (startBounds.equals(endBounds) && matricesEqual) {
            return null;
        }

        ImageView imageView = (ImageView) endValues.view;
        Drawable drawable = imageView.getDrawable();
        int drawableWidth = drawable.getIntrinsicWidth();
        int drawableHeight = drawable.getIntrinsicHeight();

        ObjectAnimator animator;
        if (drawableWidth == 0 || drawableHeight == 0) {
            animator = createNullAnimator(imageView);
        } else {
            if (startMatrix == null) {
                startMatrix = Matrix.IDENTITY_MATRIX;
            }
            if (endMatrix == null) {
                endMatrix = Matrix.IDENTITY_MATRIX;
            }
            ANIMATED_TRANSFORM_PROPERTY.set(imageView, startMatrix);
            animator = createMatrixAnimator(imageView, startMatrix, endMatrix);
        }
        return animator;
    }

    private ObjectAnimator createNullAnimator(ImageView imageView) {
        return ObjectAnimator.ofObject(imageView, ANIMATED_TRANSFORM_PROPERTY,
                NULL_MATRIX_EVALUATOR, null, null);
    }

    private ObjectAnimator createMatrixAnimator(final ImageView imageView, Matrix startMatrix,
            final Matrix endMatrix) {
        return ObjectAnimator.ofObject(imageView, ANIMATED_TRANSFORM_PROPERTY,
                new TransitionUtils.MatrixEvaluator(), startMatrix, endMatrix);
    }
}