布局***.xml:

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent"android:gravity="center"><com.chy.mytest.doubleTouchTool.ZoomImageViewandroid:id="@+id/zoomImageView"android:layout_width="match_parent"android:layout_height="match_parent"android:src="@drawable/app_logo"android:scaleType="centerInside"/></LinearLayout>

java代码：

package com.chy.mytest.doubleTouchTool;import android.animation.ObjectAnimator;import android.animation.ValueAnimator;import android.content.Context;import android.graphics.Matrix;import android.graphics.RectF;import android.graphics.drawable.Drawable;import android.util.AttributeSet;import android.view.GestureDetector;import android.view.MotionEvent;import android.view.ScaleGestureDetector;import android.view.ViewTreeObserver;import android.view.animation.AccelerateInterpolator;import android.widget.OverScroller;import androidx.appcompat.widget.AppCompatImageView;/*** 展示一个图片,可以放大/缩小 (放大后可以移动)* */public class ZoomImageView extends AppCompatImageView implements ViewTreeObserver.OnGlobalLayoutListener {private boolean mIsOneLoad = true;//初始化的比例,也就是最小比例private float mInitScale;//图片最大比例private float mMaxScale;//双击能达到的最大比例private float mMidScale;private Matrix mScaleMatrix;//捕获用户多点触控private ScaleGestureDetector mScaleGestureDetector;//移动private GestureDetector gestureDetector;//双击private boolean isEnlarge = false;//是否放大private ValueAnimator mAnimator; //双击缩放动画//滚动private OverScroller scroller;private int mCurrentX, mCurrentY;private ValueAnimator translationAnimation; //惯性移动动画//单击private OnClickListener onClickListener;//单击监听public ZoomImageView(Context context) {this(context, null);}public ZoomImageView(Context context,AttributeSet attrs) {this(context, attrs, 0);}public ZoomImageView(Context context,AttributeSet attrs,int defStyleAttr) {super(context, attrs, defStyleAttr);//记住，一定要把ScaleType设置成ScaleType.MATRIX，否则无法缩放setScaleType(ScaleType.MATRIX);scroller = new OverScroller(context);mScaleMatrix = new Matrix();//手势缩放mScaleGestureDetector = new ScaleGestureDetector(context, new ScaleGestureDetector.SimpleOnScaleGestureListener() {@Overridepublic boolean onScale(ScaleGestureDetector detector) {scale(detector);return true;}@Overridepublic void onScaleEnd(ScaleGestureDetector detector) {scaleEnd(detector);}});//滑动和双击监听gestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {@Overridepublic boolean onScroll(MotionEvent e1,MotionEvent e2,final float distanceX,final float distanceY) {//滑动监听onTranslationImage(-distanceX, -distanceY);return true;}@Overridepublic boolean onDoubleTap(MotionEvent e) {//双击监听onDoubleDrowScale(e.getX(), e.getY());return true;// 双击事件不执行}@Overridepublic boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {//滑动惯性处理mCurrentX = (int) e2.getX();mCurrentY = (int) e2.getY();RectF rectF = getMatrixRectF();if (rectF == null) {return false;}//startX为当前图片左边界的x坐标int startX = mCurrentX;int startY = mCurrentY;int minX = 0, maxX = 0, minY = 0, maxY = 0;int vX = Math.round(velocityX);int vY = Math.round(velocityY);maxX = Math.round(rectF.width());maxY = Math.round(rectF.height());if (startX != maxX || startY != maxY) {//调用fling方法，然后我们可以通过调用getCurX和getCurY来获得当前的x和y坐标//这个坐标的计算是模拟一个惯性滑动来计算出来的，我们根据这个x和y的变化可以模拟//出图片的惯性滑动scroller.fling(startX, startY, vX, vY, 0, maxX, 0, maxY, maxX, maxY);}if (translationAnimation != null && translationAnimation.isStarted())translationAnimation.end();translationAnimation = ObjectAnimator.ofFloat(0, 1);translationAnimation.setDuration(500);translationAnimation.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {@Overridepublic void onAnimationUpdate(ValueAnimator animation) {if (puteScrollOffset()) {//获得当前的x坐标int newX = scroller.getCurrX();int dx = newX - mCurrentX;mCurrentX = newX;//获得当前的y坐标int newY = scroller.getCurrY();int dy = newY - mCurrentY;mCurrentY = newY;//进行平移操作if (dx != 0 && dy != 0)onTranslationImage(dx, dy);}}});translationAnimation.start();return super.onFling(e1, e2, velocityX, velocityY);}@Overridepublic boolean onSingleTapConfirmed(MotionEvent e) {//单击事件if(onClickListener != null)onClickListener.onClick(ZoomImageView.this);return true;}});}@Overridepublic void setOnClickListener(OnClickListener onClickListener) {this.onClickListener = onClickListener;}@Overrideprotected void onAttachedToWindow() {super.onAttachedToWindow();getViewTreeObserver().addOnGlobalLayoutListener(this);}@Overrideprotected void onDetachedFromWindow() {super.onDetachedFromWindow();getViewTreeObserver().removeOnGlobalLayoutListener(this);}/*** imageView加载完成后调用，获取imageView加载完成后的图片大小*/@Overridepublic void onGlobalLayout() {if (mIsOneLoad) {//得到控件的宽和高int width = getWidth();int height = getHeight();//获取图片,如果没有图片则直接退出Drawable d = getDrawable();if (d == null)return;//获取图片的宽和高int dw = d.getIntrinsicWidth();int dh = d.getIntrinsicHeight();float scale = 1.0f;if (dw > width && dh <= height) {scale = width * 1.0f / dw;}if (dw <= width && dh > height) {scale = height * 1.0f / dh;}if ((dw <= width && dh <= height) || (dw >= width && dh >= height)) {scale = Math.min(width * 1.0f / dw, height * 1.0f / dh);}//图片原始比例，图片回复原始大小时使用mInitScale = scale;//图片双击后放大的比例mMidScale = mInitScale * 2;//手势放大时最大比例mMaxScale = mInitScale * 4;//设置移动数据,把改变比例后的图片移到中心点float translationX = width * 1.0f / 2 - dw / 2;float translationY = height * 1.0f / 2 - dh / 2;mScaleMatrix.postTranslate(translationX, translationY);mScaleMatrix.postScale(mInitScale, mInitScale, width * 1.0f / 2, height * 1.0f / 2);setImageMatrix(mScaleMatrix);mIsOneLoad = false;}}@Overridepublic boolean onTouchEvent(MotionEvent event) {return mScaleGestureDetector.onTouchEvent(event)|gestureDetector.onTouchEvent(event);}//手势操作（缩放）public void scale(ScaleGestureDetector detector) {Drawable drawable = getDrawable();if (drawable == null)return;float scale = getScale();//获取手势操作的值,scaleFactor>1说明放大，<1则说明缩小float scaleFactor = detector.getScaleFactor();//获取手势操作后的比例，当放操作后比例在[mInitScale,mMaxScale]区间时允许放大mScaleMatrix.postScale(scaleFactor, scaleFactor, detector.getFocusX(), detector.getFocusY());setImageMatrix(mScaleMatrix);removeBorderAndTranslationCenter();}//手势操作结束public void scaleEnd(ScaleGestureDetector detector) {float scale = getScale();scale = detector.getScaleFactor() * scale;if (scale < mInitScale) {scaleAnimation(mInitScale, getWidth() / 2, getHeight() / 2);} else if (scale > mMaxScale) {scaleAnimation(mMaxScale, getWidth() / 2, getHeight() / 2);}}//手势操作（移动）private void onTranslationImage(float dx, float dy) {if (getDrawable() == null)return;RectF rect = getMatrixRectF();//图片宽度小于控件宽度时不允许左右移动if (rect.width() <= getWidth())dx = 0.0f;//图片高度小于控件宽度时，不允许上下移动if (rect.height() <= getHeight())dy = 0.0f;//移动距离等于0，那就不需要移动了if (dx == 0.0f && dy == 0.0f)return;mScaleMatrix.postTranslate(dx, dy);setImageMatrix(mScaleMatrix);//去除移动边界removeBorderAndTranslationCenter();}//消除控件边界和把图片移动到中间private void removeBorderAndTranslationCenter() {RectF rectF = getMatrixRectF();if (rectF == null)return;int width = getWidth();int height = getHeight();float widthF = rectF.width();float heightF = rectF.height();float left = rectF.left;float right = rectF.right;float top = rectF.top;float bottom = rectF.bottom;float translationX = 0.0f, translationY = 0.0f;if (left > 0) {//左边有边界if (widthF > width) {//图片宽度大于控件宽度，移动到左边贴边translationX = -left;} else {//图片宽度小于控件宽度，移动到中间translationX = width * 1.0f / 2f - (widthF * 1.0f / 2f + left);}} else if (right < width) {//右边有边界if (widthF > width) {//图片宽度大于控件宽度，移动到右边贴边translationX = width - right;} else {//图片宽度小于控件宽度，移动到中间translationX = width * 1.0f / 2f - (widthF * 1.0f / 2f + left);}}if (top > 0) {//顶部有边界if (heightF > height) {//图片高度大于控件高度，去除顶部边界translationY = -top;} else {//图片高度小于控件宽度，移动到中间translationY = height * 1.0f / 2f - (top + heightF * 1.0f / 2f);}} else if (bottom < height) {//底部有边界if (heightF > height) {//图片高度大于控件高度，去除顶部边界translationY = height - bottom;} else {//图片高度小于控件宽度，移动到中间translationY = height * 1.0f / 2f - (top + heightF * 1.0f / 2f);}}mScaleMatrix.postTranslate(translationX, translationY);setImageMatrix(mScaleMatrix);}/*** 双击改变大小** @param x 点击的中心点* @param y 点击的中心点*/private void onDoubleDrowScale(float x, float y) {//如果缩放动画已经在执行，那就不执行任何事件if (mAnimator != null && mAnimator.isRunning())return;float drowScale = getDoubleDrowScale();//执行动画缩放，不然太难看了scaleAnimation(drowScale, x, y);}/*** 缩放动画** @param drowScale 缩放的比例* @param x 中心点* @param y 中心点*/private void scaleAnimation(final float drowScale, final float x, final float y) {if (mAnimator != null && mAnimator.isRunning())return;mAnimator = ObjectAnimator.ofFloat(getScale(), drowScale);mAnimator.setDuration(300);mAnimator.setInterpolator(new AccelerateInterpolator());mAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {@Overridepublic void onAnimationUpdate(ValueAnimator animation) {float value = ((float) animation.getAnimatedValue()) / getScale();mScaleMatrix.postScale(value, value, x, y);setImageMatrix(mScaleMatrix);removeBorderAndTranslationCenter();}});mAnimator.start();}//返回双击后改变的大小比例(我们希望缩放误差在deviation范围内)private float getDoubleDrowScale() {float deviation = 0.05f;float drowScale = 1.0f;float scale = getScale();if (Math.abs(mInitScale - scale) < deviation)scale = mInitScale;if (Math.abs(mMidScale - scale) < deviation)scale = mMidScale;if (Math.abs(mMaxScale - scale) < deviation)scale = mMaxScale;if (scale != mMidScale) {//当前大小不等于mMidScale,则调整到mMidScaledrowScale = mMidScale;isEnlarge = scale < mMidScale;} else {//如果等于mMidScale，则判断放大或者缩小//判断是放大或者缩小，如果上次是放大，则继续放大，缩小则继续缩小if (isEnlarge) {//放大drowScale = mMaxScale;} else {//缩小drowScale = mInitScale;}}return drowScale;}//获取图片宽高以及左右上下边界private RectF getMatrixRectF() {Drawable drawable = getDrawable();if (drawable == null) {return null;}RectF rectF = new RectF(0, 0, drawable.getMinimumWidth(), drawable.getMinimumHeight());Matrix matrix = getImageMatrix();matrix.mapRect(rectF);return rectF;}/*** 获取当前图片的缩放值** @return*/private float getScale() {float[] values = new float[9];mScaleMatrix.getValues(values);return values[Matrix.MSCALE_X];}/*** 解决和父控件滑动冲突 只要图片边界超过控件边界，返回true** @param direction* @return true 禁止父控件滑动*/@Overridepublic boolean canScrollHorizontally(int direction) {RectF rect = getMatrixRectF();if (rect == null || rect.isEmpty())return false;if (direction > 0) {return rect.right >= getWidth() + 1;} else {return rect.left <= 0 - 1;}}/*** 同楼上** @param direction* @return*/@Overridepublic boolean canScrollVertically(int direction) {RectF rect = getMatrixRectF();if (rect == null || rect.isEmpty())return false;if (direction > 0) {return rect.bottom >= getHeight() + 1;} else {return rect.top <= 0 - 1;}}}

使用代码：

package com.chy.mytest.doubleTouchTool;import android.os.Bundle;import android.view.View;import android.widget.Toast;import androidx.annotation.Nullable;import androidx.appcompat.app.AppCompatActivity;import com.chy.mytest.R;public class DoubleTouchImageViewActivity extends AppCompatActivity {private ZoomImageView zoomImageView;@Overrideprotected void onCreate(@Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_double);init();}/*** 初始化* */private void init(){zoomImageView = findViewById(R.id.zoomImageView);zoomImageView.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {Toast.makeText(getApplicationContext(),"点击当前图片",Toast.LENGTH_SHORT).show();}});}}