package com.kale.gridviewanimtest;


import android.graphics.Point;
import android.graphics.Rect;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.DecelerateInterpolator;
import android.widget.AdapterView;

import com.nineoldandroids.animation.Animator;
 
import com.nineoldandroids.animation.AnimatorListenerAdapter;
import com.nineoldandroids.animation.AnimatorSet;
import com.nineoldandroids.animation.ObjectAnimator;

public class ZoomTutorial {
    
    final private int mAnimationDuration = 300;// 動畫持續的時間，300比較合適
    private Animator mCurrentAnimator;//
 
當前的動畫物件
    
    private View mContainView;//當前螢幕中檢視最外層的容器
    private ViewGroup mThumbViewParent;//小圖片的檢視
    private View mExpandedView;//大圖片所在的檢視
    
    private Rect startBounds;//開始動畫的區域範圍
    private float startScale;//開始的比率
    private float startScaleFinal;//結束時的比率
    
    public ZoomTutorial(View containerView,View expandedView) {
        mContainView 
 
= containerView;
        mExpandedView = expandedView;
    }
    
    /**
     * 十分重要的一個方法，用於展示大的圖片
     * 
     * @param thumbView
     * @param imageResId
     */
    public void zoomImageFromThumb(final View thumbView) {
        mThumbViewParent = (ViewGroup) thumbView.getParent();
        // If there's an animation in progress, cancel it immediately and
        // proceed with this one.
        if (mCurrentAnimator != null) {
            mCurrentAnimator.cancel();
        }

        // Calculate the starting and ending bounds for the zoomed-in image.
        // This step involves lots of math. Yay, math.
        // 計算開始和結束的邊界+偏移量
        startBounds = new Rect();
        final Rect finalBounds = new Rect();// 結束的邊界
        final Point globalOffset = new Point();// 目標偏移量

        // The start bounds are the global visible rectangle of the thumbnail,
        // 開始的邊界是小圖整體可見部分的範圍
        // and the final bounds are the global visible rectangle of the container view.
        // 結束的邊界是容器的邊界
        // Also set the container view's offset as the origin for the bounds,
        // since that's the origin for the positioning animation properties (X, Y).
        thumbView.getGlobalVisibleRect(startBounds);
        // 這裡的id，container是整個佈局最外層的容器
        mContainView.getGlobalVisibleRect(finalBounds, globalOffset);

        // 開始設定偏移量
        startBounds.offset(-globalOffset.x, -globalOffset.y);
        finalBounds.offset(-globalOffset.x, -globalOffset.y);

        //設定縮放的比例和位置
        set_Center_crop(finalBounds);
        
        mExpandedView.setVisibility(View.VISIBLE);
        
        // Set the pivot point for SCALE_X and SCALE_Y transformations to the
        // top-left corner of
        // the zoomed-in view (the default is the center of the view).
        AnimatorSet animSet = new AnimatorSet();
        animSet.setDuration(1);
        animSet.play(ObjectAnimator.ofFloat(mExpandedView, "pivotX", 0f))
        .with(ObjectAnimator.ofFloat(mExpandedView, "pivotY", 0f))
        .with(ObjectAnimator.ofFloat(mExpandedView, "alpha", 1.0f));
        animSet.start();
 
        startZoomAnim(mExpandedView, startBounds, finalBounds, startScale);
         // Upon clicking the zoomed-in image, it should zoom back down to the
        // original bounds and show the thumbnail instead of the expanded image.
        startScaleFinal = startScale;
    }
    
    /**
     * 通過結束的邊界計算開始拉伸的比例
     * 
     * Adjust the start bounds to be the same aspect ratio as the final bounds
     * using the "center crop" technique. 通過 center
     * crop演算法來調整開始邊界，讓它和的結束邊界保持同一個縱橫比例，也就是長寬比 This prevents undesirable
     * stretching during the animation.//在動畫執行時保證不讓圖片拉伸 Also calculate the start
     * scaling factor (the end scaling factor is always 1.0).
     * 我們也需要計算開始的比率因子，結束比例一直是1.0.因為是將圖片從小放到自己的大小。
     */
    private void set_Center_crop(Rect finalBounds) {
        if ((float) finalBounds.width() / finalBounds.height() > (float) 
                startBounds.width() / startBounds.height()) {
            // Extend start bounds horizontally
            startScale = (float) startBounds.height() / finalBounds.height();
            float startWidth = startScale * finalBounds.width();
            float deltaWidth = (startWidth - startBounds.width()) / 2;
            startBounds.left -= deltaWidth;
            startBounds.right += deltaWidth;
        } else {
            // Extend start bounds vertically
            startScale = (float) startBounds.width() / finalBounds.width();
            float startHeight = startScale * finalBounds.height();
            float deltaHeight = (startHeight - startBounds.height()) / 2;
            startBounds.top -= deltaHeight;
            startBounds.bottom += deltaHeight;
        }
    }

    /**
     * @param v  執行動畫的view
     * @param startBounds  開始的邊界
     * @param finalBounds  結束時的邊界
     * @param startScale  開始的拉伸比率
     */
    public void startZoomAnim(View v, Rect startBounds, Rect finalBounds, float startScale) {
        // Construct and run the parallel animation of the four translation and
        // scale properties (X, Y, SCALE_X, and SCALE_Y).
        AnimatorSet set = new AnimatorSet();
        set.play(
            ObjectAnimator.ofFloat(v, "x", startBounds.left, finalBounds.left))
            .with(ObjectAnimator.ofFloat(v, "y", startBounds.top, finalBounds.top))
            .with(ObjectAnimator.ofFloat(v, "scaleX", startScale, 1f))
            .with(ObjectAnimator.ofFloat(v, "scaleY", startScale, 1f));
        
        set.setDuration(mAnimationDuration);
        set.setInterpolator(new DecelerateInterpolator());
        set.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                mCurrentAnimator = null;
                if (listener != null) {
                    listener.onExpanded();
                }
            }

            @Override
            public void onAnimationCancel(Animator animation) {
                mCurrentAnimator = null;
                if (listener != null) {
                    listener.onExpanded();
                }
            }
        });
        set.start();
        mCurrentAnimator = set;
    }

    /**
     * 在GridView中，使用getChildAt(index)的取值，只能是當前可見區域（列表可滾動）的子項！
     * 因為子項會進行復用。這裡強制轉換了下，變成了GridView，實際使用中需要進行修改
     * 【參考】
     * http://xie2010.blog.163.com/blog/static/211317365201402395944633/
     * http://blog.csdn.net/you_and_me12/article/details/7271006
     * 
     * @param position
     * @return 判斷這個position的view是否現在顯示在螢幕上，如果沒有顯示就返回false
     */
    public boolean getScaleFinalBounds(int position) {
        //得到顯示區域中第一個子檢視的序號
        int firstPosition = ((AdapterView<?>)mThumbViewParent).getFirstVisiblePosition();
        View childView = mThumbViewParent.getChildAt(position - firstPosition);
        
        startBounds = new Rect();
        final Rect finalBounds = new Rect();
        final Point globalOffset = new Point();
        
        try {
            //通過這個計算startBounds，得到當前view的位置，從而設定偏移值
            childView.getGlobalVisibleRect(startBounds);
        } catch (Exception e) {
            return false;
        }
        mContainView.findViewById(R.id.container).getGlobalVisibleRect(finalBounds, globalOffset);
        startBounds.offset(-globalOffset.x, -globalOffset.y);
        finalBounds.offset(-globalOffset.x, -globalOffset.y);
        //設定比率
        set_Center_crop(finalBounds);
        
        startScaleFinal = startScale;
        return true;
    }
    
    /**
     * 根據position執行動畫，如果這個圖片在當前螢幕顯示範圍內，那就執行縮小。否則直接漸變
     * @param position
     */
    public void closeZoomAnim(int position) {
        if (mCurrentAnimator != null) {
            mCurrentAnimator.cancel();
        }
        // Animate the four positioning/sizing properties in parallel,back to their original values.
        AnimatorSet set = new AnimatorSet();
        /**
         * 因為展開圖可能是在viewpager中，所以現在顯示的圖片，或許並不是第一次開啟的圖片，這裡應該考慮兩點
         * 1.改變圖片縮小後回到的位置
         * 2.如果圖片縮小後回到的位置不在螢幕中，直接漸變消失
         */
        boolean isInBound = getScaleFinalBounds(position);
        if (isInBound) {
            set.play(ObjectAnimator.ofFloat(mExpandedView, "x", startBounds.left))
                .with(ObjectAnimator.ofFloat(mExpandedView, "y", startBounds.top))
                .with(ObjectAnimator.ofFloat(mExpandedView, "scaleX", startScaleFinal))
                .with(ObjectAnimator.ofFloat(mExpandedView, "scaleY", startScaleFinal));
        } else {
            // 如果當前顯示的圖片不在gridview當前顯示的圖片中，等於越界了。這時我們就不執行縮放操作，直接漸變消失即可。
            ObjectAnimator alphaAnimator = ObjectAnimator.ofFloat(mExpandedView, "alpha", 0.1f);
            set.play(alphaAnimator);
        }
        set.setDuration(mAnimationDuration);
        set.setInterpolator(new DecelerateInterpolator());
        set.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                mExpandedView.clearAnimation();
                mExpandedView.setVisibility(View.GONE);
                mCurrentAnimator = null;
                if (listener != null) {
                    listener.onThumbed();
                }
            }

            @Override
            public void onAnimationCancel(Animator animation) {
                mExpandedView.clearAnimation();
                mExpandedView.setVisibility(View.GONE);
                mCurrentAnimator = null;
                if (listener != null) {
                    listener.onThumbed();
                }
            }
        });
        set.start();
        mCurrentAnimator = set;
    }
    
    private OnZoomListener listener;
    
    public void setOnZoomListener(OnZoomListener l) {
        listener = l;
    }
    
    public interface OnZoomListener {
        public void onExpanded();//點選後展示大圖成功後呼叫
        public void onThumbed();//點選後縮小回小圖時呼叫
    }
    
}