android 图片浏览(支持左右平滑滑动和pinch缩放）

最近整理了一下项目中用到的图片浏览的一些代码，这个图片浏览工具与系统的相册功能类似，全屏浏览图片，支持一系列手势操作，滑动切换以及多指缩放。

图片列表的容器使用了系统的gallery类实现，在View的实现上，重写了系统的ImageView对象，监听手势操作。

两个主要类的实现代码如下：

gallery的实现：

package com.xiaobai.viewimage;

import android.content.Context;
import android.graphics.Matrix;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Gallery;

public class PicGallery extends Gallery {
    private static final boolean DEBUG = Logger.DEBUG && false;
    private GestureDetector gestureScanner;
    private MyImageView imageView;

    public PicGallery(Context context) {
        super(context);

    }

    public PicGallery(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public void setDetector(GestureDetector dectector) {
        gestureScanner = dectector;
    }

    public PicGallery(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.setOnTouchListener(new OnTouchListener() {

            float baseValue;
            float originalScale;

            @Override
            public boolean onTouch(View v, MotionEvent event) {
                View view = PicGallery.this.getSelectedView();
                if (view instanceof MyImageView) {
                    imageView = (MyImageView) view;

                    if (event.getAction() == MotionEvent.ACTION_DOWN) {
                        baseValue = 0;
                        originalScale = imageView.getScale();
                    }
                    if (event.getAction() == MotionEvent.ACTION_MOVE) {
                        if (event.getPointerCount() == 2) {
                            float x = event.getX(0) - event.getX(1);
                            float y = event.getY(0) - event.getY(1);
                            float value = (float) Math.sqrt(x * x + y * y);// 计算两点的距离
                            // System.out.println("value:" + value);
                            if (baseValue == 0) {
                                baseValue = value;
                            } else {
                                float scale = value / baseValue;// 当前两点间的距离除以手指落下时两点间的距离就是需要缩放的比例。
                                // scale the image
                                imageView.zoomTo(originalScale * scale, x
                                        + event.getX(1), y + event.getY(1));

                            }
                        }
                    }
                }
                return false;
            }

        });
    }

    float v[] = new float[9];
    
    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
            float distanceY) {
        View view = PicGallery.this.getSelectedView();
        if (view instanceof MyImageView) {
            
            float xdistance = calXdistance(e1, e2);
            float min_distance = PictureViewActivity.screenWidth / 4f;
            Logger.d(DEBUG,"xdistance=" + xdistance + ",min_distance="
                    + min_distance);
            if (isScrollingLeft(e1, e2) && xdistance > min_distance) {
                kEvent = KeyEvent.KEYCODE_DPAD_LEFT;
            } else if (!isScrollingLeft(e1, e2) && xdistance > min_distance) {
                kEvent = KeyEvent.KEYCODE_DPAD_RIGHT;
            }
            
            imageView = (MyImageView) view;

            Matrix m = imageView.getImageMatrix();
            m.getValues(v);
            // 图片实时的上下左右坐标
            float left, right;
            // 图片的实时宽，高
            float width = imageView.getScale() * imageView.getImageWidth();
            float height = imageView.getScale() * imageView.getImageHeight();
            
            if ((int) width <= PictureViewActivity.screenWidth
                    && (int) height <= PictureViewActivity.screenHeight)// 如果图片当前大小<屏幕大小，直接处理滑屏事件
            {
                super.onScroll(e1, e2, distanceX, distanceY);
            } else {
                left = v[Matrix.MTRANS_X];
                right = left + width;
                Rect r = new Rect();
                imageView.getGlobalVisibleRect(r);

                if (distanceX > 0)// 向左滑动
                {
                    if (r.left > 0 || right < PictureViewActivity.screenWidth) {// 判断当前ImageView是否显示完全
                        super.onScroll(e1, e2, distanceX, distanceY);
                    } else {
                        imageView.postTranslate(-distanceX, -distanceY);
                    }
                } else if (distanceX < 0)// 向右滑动
                {
                    if (r.right < PictureViewActivity.screenWidth || left > 0) {
                        super.onScroll(e1, e2, distanceX, distanceY);
                    } else {
                        imageView.postTranslate(-distanceX, -distanceY);
                    }
                }

            }

        } else {
            super.onScroll(e1, e2, distanceX, distanceY);
        }
        return false;
    }

    private boolean isScrollingLeft(MotionEvent e1, MotionEvent e2) {
        return e2.getX() > e1.getX();
    }

    private float calXdistance(MotionEvent e1, MotionEvent e2) {
        return Math.abs(e2.getX() - e1.getX());
    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
            float velocityY) {
        return false;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        //Logger.d(DEBUG,"[PicGallery.onTouchEvent]"+"PicGallery.onTouchEvent");
        if (gestureScanner != null) {
            gestureScanner.onTouchEvent(event);
        }
        switch (event.getAction()) {
        case MotionEvent.ACTION_UP:
            // 判断边界是否越界
            View view = PicGallery.this.getSelectedView();
            if (view instanceof MyImageView) {
                
                if(kEvent != KEY_INVALID) { // 是否切换上一页或下一页
                    onKeyDown(kEvent, null);
                    kEvent = KEY_INVALID;
                }
                
                imageView = (MyImageView) view;
                float width = imageView.getScale() * imageView.getImageWidth();
                float height = imageView.getScale()
                        * imageView.getImageHeight();
                // Logger.LOG("onTouchEvent", "width=" + width + ",height="
                // + height + ",screenWidth="
                // + PictureViewActivity.screenWidth + ",screenHeight="
                // + PictureViewActivity.screenHeight);
                if ((int) width <= PictureViewActivity.screenWidth
                        && (int) height <= PictureViewActivity.screenHeight)// 如果图片当前大小<屏幕大小，判断边界
                {
                    break;
                }
                float v[] = new float[9];
                Matrix m = imageView.getImageMatrix();
                m.getValues(v);
                float top = v[Matrix.MTRANS_Y];
                float bottom = top + height;
                if (top < 0 && bottom < PictureViewActivity.screenHeight) {
//                    imageView.postTranslateDur(-top, 200f);
                    imageView.postTranslateDur(PictureViewActivity.screenHeight
                            - bottom, 200f);
                }
                if (top > 0 && bottom > PictureViewActivity.screenHeight) {
//                    imageView.postTranslateDur(PictureViewActivity.screenHeight
//                            - bottom, 200f);
                    imageView.postTranslateDur(-top, 200f);
                }
                
                float left =v[Matrix.MTRANS_X];
                float right = left + width;
                if(left<0 && right< PictureViewActivity.screenWidth){
//                    imageView.postTranslateXDur(-left, 200f);
                    imageView.postTranslateXDur(PictureViewActivity.screenWidth
                            - right, 200f);
                }
                if(left>0 && right>PictureViewActivity.screenWidth){
//                    imageView.postTranslateXDur(PictureViewActivity.screenWidth
//                            - right, 200f);
                    imageView.postTranslateXDur(-left, 200f);
                }
            }
            break;
        }
        return super.onTouchEvent(event);
    }
    
    int kEvent = KEY_INVALID; //invalid
    public static final int KEY_INVALID = -1;
}

重写ImageView：

　　apk下载链接：http://download.csdn.net/download/aimfaraway/5349925

　　源码链接：https://github.com/devxiaobai/ViewImage