自定义Gallery 滑动中图片自动突出显示

最新推荐文章于 2025-08-21 13:25:55 发布

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最新推荐文章于 2025-08-21 13:25:55 发布

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文章标签：移动开发

原文链接：http://www.cnblogs.com/shanzei/archive/2012/03/24/2415642.html

本文介绍了一个名为 AnimatedSizingGallery 的自定义 Android Gallery 控件，它可以在选择项切换时动态调整图片大小，提供了 zoom in 和 zoom out 的动画效果。

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package org.pskink;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Matrix;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.Transformation;
import android.widget.AdapterView;
import android.widget.Gallery;
import android.widget.ImageView;
import android.widget.AdapterView.OnItemSelectedListener;

public class AnimatedSizingGallery extends Gallery implements OnItemSelectedListener {
public static final String TAG = "AnimatedSizingGallery";
private static final int MSG_ZOOM_IN = 1;
private  static final long DELAY = 100;

private View mPrev;
private float mAnimationScale;
private float mAnimationOffsetY;
private int mAnimationDuration;

public AnimatedSizingGallery(Context context, AttributeSet attrs) {
super(context, attrs);
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.AnimatedSizingGallery);
        mAnimationScale = a.getFloat(R.styleable.AnimatedSizingGallery_animationScale, 2);
        mAnimationOffsetY = a.getFloat(R.styleable.AnimatedSizingGallery_animationOffsetY, 0);
        mAnimationDuration = a.getInteger(R.styleable.AnimatedSizingGallery_animationDuration, 500);
        a.recycle();
        setOnItemSelectedListener(this);
    }

public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
if (mPrev != null) {
            zoomOut();
        }
        mPrev = view;
        mGalleryHandler.removeCallbacksAndMessages(view);
        Message msg = Message.obtain(mGalleryHandler, MSG_ZOOM_IN, view);
        mGalleryHandler.sendMessageDelayed(msg, DELAY);
    }

public void onNothingSelected(AdapterView<?> parent) {
        Log.d(TAG, "onNothingSelected called !!!");
if (mPrev != null) {
            zoomOut();
            mPrev = null;
        }
    }

private void zoomOut() {
if (mGalleryHandler.hasMessages(MSG_ZOOM_IN, mPrev)) {
            mGalleryHandler.removeCallbacksAndMessages(mPrev);
        } else {
            ZoomAnimation a = (ZoomAnimation) mPrev.getAnimation();
            a.resetForZoomOut();
            mPrev.startAnimation(a);
        }
    }

    Handler mGalleryHandler = new Handler() {
        @Override
public void dispatchMessage(Message msg) {
if (msg.what == MSG_ZOOM_IN) {
                ImageView view = (ImageView) msg.obj;
                Animation a = new ZoomAnimation(view, 1, mAnimationScale, mAnimationOffsetY, mAnimationDuration);
                view.startAnimation(a);
            }
        }
    };

class ZoomAnimation extends Animation {
private float mFrom;
private float mTo;
private float mOffsetY;
private int mPivotX;
private int mPivotY;
private float mInterpolatedTime;

public ZoomAnimation(View v, float from, float to, float offsetY, int duration) {
super();
            mFrom = from;
            mTo = to;
            mOffsetY = offsetY * v.getHeight();
            setDuration(duration);
            setFillAfter(true);
            mPivotX = v.getWidth() / 2;
            mPivotY = v.getHeight() / 2;
        }

public void resetForZoomOut() {
            reset();
            mOffsetY = 0;
            mFrom = mFrom + (mTo - mFrom) * mInterpolatedTime;
            mTo = 1;
        }

        @Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
            mInterpolatedTime = interpolatedTime;
float s = mFrom + (mTo - mFrom) * interpolatedTime;
            Matrix matrix = t.getMatrix();
if (mOffsetY != 0) {
                matrix.preTranslate(0, mOffsetY * interpolatedTime);
            }
if (mTo == 1) {
                matrix.preRotate(360 * interpolatedTime, mPivotX, mPivotY);
            }
            matrix.preScale(s, s, mPivotX, mPivotY);
        }
    }
}