自定义圆形图片实现多点触控放大缩小和拖动

package com.bwie.view;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.Bitmap.Config;
import android.graphics.PorterDuff.Mode;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.FloatMath;
import android.view.MotionEvent;
import android.view.animation.TranslateAnimation;
import android.widget.ImageView;
/**
* 继承ImageView 实现了多点触碰的拖动和缩放
* @author lihua
*/
public class TouchView extends ImageView {

private Paint p;
static final int NONE = 0;
static final int DRAG = 1;     //拖动中
static final int ZOOM = 2;     //缩放中
static final int BIGGER = 3;   //放大ing
static final int SMALLER = 4;  //缩小ing
private int mode = NONE;       //当前的事件

private float beforeLenght;   //两触点距离
private float afterLenght;    //两触点距离
private float scale = 0.04f;  //缩放的比例 X Y方向都是这个值 越大缩放的越快

private int screenW;
private int screenH;

/*处理拖动 变量 */
private int start_x;
private int start_y;
private int stop_x ;
private int stop_y ;

private TranslateAnimation trans; //处理超出边界的动画

/**
* 默认构造函数
* @param context
*/
public TouchView(Context context){
super(context);
}
/**
* 该构造方法在静态引入XML文件中是必须的
* @param context
* @param paramAttributeSet
*/
public TouchView(Context context,AttributeSet paramAttributeSet){
super(context,paramAttributeSet);
// TODO Auto-generated constructor stub
p = new Paint();
}

@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
Drawable drawable = getDrawable();
if(null!=drawable){
Bitmap bitmap = ((BitmapDrawable)drawable).getBitmap();
Bitmap b = getCircleBitmap(bitmap, 14);
final Rect rectSrc = new Rect(0, 0, b.getWidth(), b.getHeight());
final Rect rectDest = new Rect(0, 0, getWidth(), getHeight());
p.reset();
canvas.drawBitmap(b, rectSrc,rectDest, p);

}else{
super.onDraw(canvas);
}

}

private Bitmap getCircleBitmap(Bitmap bitmap,int pixels){
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final int color = 0xff424242;
final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
p.setAntiAlias(true);
int x = bitmap.getWidth();
canvas.drawCircle(x/2, x/2, x/2, p);
p.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, p);
return output;
}
/**
* 该构造函数在动态创建时，指定图片的初始高宽
* @param context
* @param w
* @param h
*/
public TouchView(Context context,int w,int h) {
super(context);
this.setPadding(0, 0, 0, 0);
screenW = w;
screenH = h;
}

/**
* 就算两点间的距离
*/
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);
}

/**
* 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:
if (spacing(event) > 10f) {
mode = ZOOM;
beforeLenght = spacing(event);
}
break;
case MotionEvent.ACTION_UP:
/*判断是否超出范围     并处理*/
int disX = 0;
int disY = 0;
if(getHeight()<=screenH || this.getTop()<0)
{
if(this.getTop()<0 )
{
int dis = getTop();
this.layout(this.getLeft(), 0, this.getRight(), 0 + this.getHeight());
disY = dis - getTop();
}
else if(this.getBottom()>screenH)
{
disY = getHeight()- screenH+getTop();
this.layout(this.getLeft(), screenH-getHeight(), this.getRight(), screenH);
}
}
if(getWidth()<=screenW)
{
if(this.getLeft()<0)
{
disX = getLeft();
this.layout(0, this.getTop(), 0+getWidth(), this.getBottom());
}
else if(this.getRight()>screenW)
{
disX = getWidth()-screenW+getLeft();
this.layout(screenW-getWidth(), this.getTop(), screenW, this.getBottom());
}
}
if(disX!=0 || disY!=0)
{
trans = new TranslateAnimation(disX, 0, disY, 0);
trans.setDuration(500);
this.startAnimation(trans);
}
mode = NONE;
break;
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
break;
case MotionEvent.ACTION_MOVE:
/*处理拖动*/
if (mode == DRAG) {
if(Math.abs(stop_x-start_x-getLeft())<88 && Math.abs(stop_y - start_y-getTop())<85)
{
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) {

if(flag==BIGGER) {
this.setFrame(this.getLeft()-(int)(temp*this.getWidth()),
this.getTop()-(int)(temp*this.getHeight()),
this.getRight()+(int)(temp*this.getWidth()),
this.getBottom()+(int)(temp*this.getHeight()));
}else if(flag==SMALLER){
this.setFrame(this.getLeft()+(int)(temp*this.getWidth()),
this.getTop()+(int)(temp*this.getHeight()),
this.getRight()-(int)(temp*this.getWidth()),
this.getBottom()-(int)(temp*this.getHeight()));
}
}

/**
* 实现处理拖动
*/
private void setPosition(int left,int top,int right,int bottom) {
this.layout(left,top,right,bottom);
}
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/r
9f38
es/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="@android:color/black"
>

<com.bwie.view.TouchView
android:layout_width="200dp"
android:layout_height="200dp"
android:src="@drawable/aefwfaw"
android:scaleType="matrix"
android:id="@+id/img" />

</LinearLayout>