当时百度的。实在没记住出处。效果很理想，就收藏了。
package com.demo.pinch;
import android.content.Context;
import android.graphics.Bitmap;
import android.util.FloatMath;
import android.view.MotionEvent;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.Animation;
import android.view.animation.Animation.AnimationListener;
import android.view.animation.ScaleAnimation;
import android.view.animation.TranslateAnimation;
import android.widget.ImageView;
/**
* ImageView Tonuch
*
* @author Laladin.SYD
*
*/
public class PinchableImageView extends ImageView {
static final int NONE = 0;
// 拖动中
static final int DRAG = 1;
// 缩放中
static final int ZOOM = 2;
// 放大ing
static final int BIGGER = 3;
// 缩小ing
static final int SMALLER = 4;
// 关闭缩放动画
static final int OPENSCALE = 1;
// 关闭移动动画
static final int OPENTRANS = 2;
// 当前的事件
private int mode = NONE;
// 两触点距离
private float beforeLenght;
// 两触点距离
private float afterLenght;
// 缩放的比例 X Y方向都是这个值 越大缩放的越快
private float scale = 0.06f;
/* 处理拖动 变量 */
private int screenW;
private int screenH;
private int start_x;
private int start_y;
private int stop_x;
private int stop_y;
private TranslateAnimation trans;
/* Bitmap的宽高 */
private int bmWidth;
private int bmHeight;
// 处理超出边界的动画
private Bitmap bitmap;
private float maxScale = 2.0f;
private float minScale = 1.0f;
// 记录初始宽度，用于缩放回弹
private int startWidth = 0;
private float piovtX = 0.5f;
private float piovtY = 0.5f;
// 默认开启所有动画
private int AnimSwitch = OPENSCALE | OPENTRANS;
/**
* 构造函数
*
* @param context
* 相关上下文
* @param w
* 容器的宽
* @param h
* 容器的高
*/
public PinchableImageView(Context context, int w, int h) {
super(context);
this.setPadding(0, 0, 0, 0);
screenW = w;
screenH = h;
}
@Override
public void setImageBitmap(Bitmap bm) {
super.setImageBitmap(bm);
// 重置startWidth
startWidth = 0;
bmWidth = bm.getWidth();
bmHeight = bm.getHeight();
if (bitmap != null && !bitmap.isRecycled())
bitmap.recycle();
bitmap = bm;
}
/**
* 释放ImageView的Bitmap
*/
public void recycle() {
setImageBitmap(null);
if (bitmap != null && !bitmap.isRecycled())
bitmap.recycle();
}
/**
* 计算两点间的距离
*/
private float spacing(MotionEvent event) {
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return FloatMath.sqrt(x * x + y * y);
}
private float[] center;
/**
* 计算两点间的中心点
*/
private float[] centerPostion(MotionEvent event) {
float[] center = new float[2];
float x = event.getX(0);
float y = event.getY(0);
float x1 = event.getX(1);
float y1 = event.getY(1);
/* x,y分别的距离 */
center[0] = Math.abs((x1 - x) / 2);
center[1] = Math.abs((y1 - y) / 2);
center[0] = Math.max(x, x1) - center[0];
center[1] = Math.max(y, y1) - center[1];
return center;
}
/**
* 设置ImageView大小等于显示的内容大小
*/
public void setRect() {
float scale = Math.min((float) getWidth() / (float) bmWidth,
(float) getHeight() / (float) bmHeight);
int w = (int) ((float) bmWidth * scale) + 1;
int h = (int) ((float) bmHeight * scale) + 1;
// int t=(screenH-h)/2;
// int l=(screenW-w)/2;
int t = getTop();
int l = getLeft();
layout(l, t, l + w, t + h);
}
/**
* 处理各种移动回弹
*
* @param disX
* X的偏移
* @param disY
* Y的偏移
*/
public void Rebound(int disX, int disY) {
this.layout(getLeft() + disX, getTop() + disY, getLeft() + disX
+ getWidth(), getTop() + disY + getHeight());
if ((AnimSwitch & OPENTRANS) == 0)
return;
trans = new TranslateAnimation(-disX, 0, -disY, 0);
trans.setInterpolator(new AccelerateInterpolator());
trans.setDuration(300);
this.startAnimation(trans);
}
/**
* 处理各种缩放回弹
*/
public boolean ReScale() {
float scaleX = 1f;
float scaleY = 1f;
int width = getWidth();
int height = getHeight();
int l, t, r, b;
if (center == null)
return false;
if (getWidth() > startWidth * maxScale) {
while (getWidth() > startWidth * maxScale) {
l = this.getLeft() + (int) (center[0] * this.getWidth());
t = this.getTop() + (int) (center[1] * this.getHeight());
r = this.getRight()
- (int) ((scale - center[0]) * this.getWidth());
b = this.getBottom()
- (int) ((scale - center[1]) * this.getHeight());
this.setFrame(l, t, r, b);
}
scaleX = (float) width / (float) getWidth();
scaleY = (float) height / (float) getHeight();
}
if (getWidth() < startWidth * minScale) {
while (getWidth() < startWidth * minScale) {
l = this.getLeft() - (int) (center[0] * this.getWidth());
t = this.getTop() - (int) (center[1] * this.getHeight());
r = this.getRight()
+ (int) ((scale - center[0]) * this.getWidth());
b = this.getBottom()
+ (int) ((scale - center[1]) * this.getHeight());
this.setFrame(l, t, r, b);
}
scaleX = (float) width / (float) getWidth();
scaleY = (float) height / (float) getHeight();
}
if (scaleX == 1f && scaleY == 1f)
return false;
if ((AnimSwitch & OPENSCALE) == 0) {
setRect();
onRebound();
return true;
}
ScaleAnimation scaleanim = new ScaleAnimation(scaleX, 1f, scaleY, 1f,
ScaleAnimation.RELATIVE_TO_SELF, piovtX,
ScaleAnimation.RELATIVE_TO_SELF, piovtY);
scaleanim.setDuration(300);
scaleanim.setInterpolator(new AccelerateInterpolator());
scaleanim.setAnimationListener(new AnimationListener() {
@Override
public void onAnimationStart(Animation paramAnimation) {
}
@Override
public void onAnimationRepeat(Animation paramAnimation) {
}
@Override
public void onAnimationEnd(Animation paramAnimation) {
setRect();
onRebound();
}
});
this.startAnimation(scaleanim);
return true;
}
/**
* 处理超范围回弹
*/
private void onRebound() {
/* 判断是否超出范围 并处理 */
int disX = 0, disY = 0;
if (getHeight() < screenH) {
disY = (screenH - getHeight()) / 2 - getTop();
}
if (getWidth() < screenW) {
disX = (screenW - getWidth()) / 2 - getLeft();
}
if (getHeight() >= screenH) {
if (getTop() > 0)
disY = -getTop();
if (getBottom() < screenH)
disY = screenH - getBottom();
}
if (getWidth() >= screenW) {
if (getLeft() > 0)
disX = -getLeft();
if (getRight() < screenW)
disX = screenW - getRight();
}
// 开始回弹
Rebound(disX, disY);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right,
int bottom) {
// TODO Auto-generated method stub
super.onLayout(changed, left, top, right, bottom);
if (startWidth == 0) {
startWidth = right - left;
setRect();
AnimSwitch = 0;
onRebound();
AnimSwitch = OPENSCALE | OPENTRANS;
}
}
/**
* 处理触碰..
*/
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
mode = DRAG;
stop_x = (int) event.getRawX();
stop_y = (int) event.getRawY();
start_x = (int) event.getX();
start_y = stop_y - this.getTop();
if (event.getPointerCount() == 2)
beforeLenght = spacing(event);
break;
case MotionEvent.ACTION_POINTER_DOWN:
/** 下面三句用于计算缩放中心点位置 **/
center = centerPostion(event);
piovtX = center[0] / getWidth();
piovtY = center[1] / getHeight();
center[0] = (center[0] / getWidth()) * scale;
center[1] = (center[1] / getHeight()) * scale;
if (spacing(event) > 10f) {
mode = ZOOM;
beforeLenght = spacing(event);
}
break;
case MotionEvent.ACTION_UP:
mode = NONE;
//setRect();
/* 判断是否超过缩放界限 */
//if (!ReScale())
// onRebound();
break;
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
break;
case MotionEvent.ACTION_MOVE:
/* 处理拖动 */
if (mode == DRAG) {
this.setPosition(stop_x - start_x, stop_y - start_y, stop_x
+ this.getWidth() - start_x,
stop_y - start_y + this.getHeight());
stop_x = (int) event.getRawX();
stop_y = (int) event.getRawY();
}
/* 处理缩放 */
else if (mode == ZOOM) {
if (spacing(event) > 10f) {
afterLenght = spacing(event);
float gapLenght = afterLenght - beforeLenght;
if (gapLenght == 0) {
break;
} else if (Math.abs(gapLenght) > 5f) {
if (gapLenght > 0) {
this.setScale(scale, BIGGER);
} else {
this.setScale(scale, SMALLER);
}
beforeLenght = afterLenght;
}
}
}
break;
}
return true;
}
/**
* 实现处理缩放
*/
private void setScale(float temp, int flag) {
int l = 0, t = 0, r = 0, b = 0;
if (flag == BIGGER) {
l = this.getLeft() - (int) (center[0] * this.getWidth());
t = this.getTop() - (int) (center[1] * this.getHeight());
r = this.getRight() + (int) ((scale - center[0]) * this.getWidth());
b = this.getBottom()
+ (int) ((scale - center[1]) * this.getHeight());
} else if (flag == SMALLER) {
l = this.getLeft() + (int) (center[0] * this.getWidth());
t = this.getTop() + (int) (center[1] * this.getHeight());
r = this.getRight() - (int) ((scale - center[0]) * this.getWidth());
b = this.getBottom()
- (int) ((scale - center[1]) * this.getHeight());
}
this.setFrame(l, t, r, b);
}
/**
* 实现处理拖动
*/
private void setPosition(int left, int top, int right, int bottom) {
this.layout(left, top, right, bottom);
}
}