前言
之前因为项目需求，其中使用到了图片的单击显示取消，图片平移缩放功能，昨天突然想再加上图片的旋转功能，在网上看了很多相关的例子，可是没看到能同时实现我想要的功能的。
需求：
（1）图片平移、缩放、旋转等一系列操作后，图片需要自动居中显示。
（2）图片旋转后选自动水平显示或者垂直显示
（3）图片在放大缩小的同时都能旋转
Demo实现部分效果截图
Demo主要代码
Java
MainActivity.java package com.practice.noyet.rotatezoomimageview; import android.app.Activity; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Matrix; import android.graphics.PointF; import android.graphics.RectF; import android.os.AsyncTask; import android.os.Bundle; import android.util.DisplayMetrics; import android.view.MotionEvent; import android.view.View; import android.widget.ImageView; import com.ypy.eventbus.EventBus; import java.io.File; import java.math.BigDecimal; /** * package: com.practice.noyet.rotatezoomimageview * Created by noyet on 2015/11/11. */ public class MainActivity extends Activity implements View.OnTouchListener { private ImageView mImageView; private PointF point0 = new PointF(); private PointF pointM = new PointF(); private final int NONE = 0; /** * 平移 */ private final int DRAG = 1; /** * 旋转、缩放 */ private final int ZOOM = 2; /** * 设定事件模式 */ private int mode = NONE; /** * 图片缩放矩阵 */ private Matrix matrix = new Matrix(); /** * 保存触摸前的图片缩放矩阵 */ private Matrix savedMatrix = new Matrix(); /** * 保存触点移动过程中的图片缩放矩阵 */ private Matrix matrix1 = new Matrix(); /** * 屏幕高度 */ private int displayHeight; /** * 屏幕宽度 */ private int displayWidth; /** * 最小缩放比例 */ protected float minScale = 1f; /** * 最大缩放比例 */ protected float maxScale = 3f; /** * 当前缩放比例 */ protected float currentScale = 1f; /** * 多点触摸2个触摸点间的起始距离 */ private float oldDist; /** * 多点触摸时图片的起始角度 */ private float oldRotation = 0; /** * 旋转角度 */ protected float rotation = 0; /** * 图片初始宽度 */ private int imgWidth; /** * 图片初始高度 */ private int imgHeight; /** * 设置单点触摸退出图片显示时，单点触摸的灵敏度（可针对不同手机单独设置） */ protected final int MOVE_MAX = 2; /** * 单点触摸时手指触发的‘MotionEvent.ACTION_MOVE'次数 */ private int fingerNumMove = 0; private Bitmap bm; /** * 保存matrix缩放比例 */ private float matrixScale= 1; /*private String imagePath;*/ /** * 显示被存入缓存中的网络图片 * * @param event 观察者事件 */ public void onEventMainThread(CustomEventBus event) { if (event == null) { return; } if (event.type == CustomEventBus.EventType.SHOW_PICTURE) { bm = (Bitmap) event.obj; showImage(); } } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initData(); } public void initData() { // TODO Auto-generated method stub bm = BitmapFactory.decodeResource(getResources(), R.drawable.alipay); DisplayMetrics dm = getResources().getDisplayMetrics(); displayWidth = dm.widthPixels; displayHeight = dm.heightPixels; mImageView = (ImageView) findViewById(R.id.image_view); mImageView.setOnTouchListener(this); showImage(); //显示网络图片时使用 /*File file = MainApplication.getInstance().getImageCache() .getDiskCache().get(图片路径); if (!file.exists()) { Toast.makeText(this, "图片路径错误", Toast.LENGTH_SHORT).show(); } else { new MyTask().execute(file); }*/ } @Override public boolean onTouch(View view, MotionEvent event) { ImageView imageView = (ImageView) view; switch (event.getAction() & MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_DOWN: savedMatrix.set(matrix); point0.set(event.getX(), event.getY()); mode = DRAG; System.out.println("MotionEvent--ACTION_DOWN"); break; case MotionEvent.ACTION_POINTER_DOWN: oldDist = spacing(event); oldRotation = rotation(event); savedMatrix.set(matrix); setMidPoint(pointM, event); mode = ZOOM; System.out.println("MotionEvent--ACTION_POINTER_DOWN---" + oldRotation); break; case MotionEvent.ACTION_UP: if (mode == DRAG & (fingerNumMove this.finish(); } checkView(); centerAndRotate(); imageView.setImageMatrix(matrix); System.out.println("MotionEvent--ACTION_UP"); fingerNumMove = 0; break; case MotionEvent.ACTION_POINTER_UP: mode = NONE; System.out.println("MotionEvent--ACTION_POINTER_UP"); break; case MotionEvent.ACTION_MOVE: operateMove(event); imageView.setImageMatrix(matrix1); fingerNumMove++; System.out.println("MotionEvent--ACTION_MOVE"); break; } return true; } @Override protected void onDestroy() { // TODO Auto-generated method stub super.onDestroy(); if (bm != null & !bm.isRecycled()) { bm.recycle(); // 回收图片所占的内存 System.gc(); // 提醒系统及时回收 } } /** * 显示图片 */ private void showImage() { imgWidth = bm.getWidth(); imgHeight = bm.getHeight(); mImageView.setImageBitmap(bm); matrix.setScale(1, 1); centerAndRotate(); mImageView.setImageMatrix(matrix); } /** * 触点移动时的操作 * * @param event 触摸事件 */ private void operateMove(MotionEvent event) { matrix1.set(savedMatrix); switch (mode) { case DRAG: matrix1.postTranslate(event.getX() - point0.x, event.getY() - point0.y); break; case ZOOM: rotation = rotation(event) - oldRotation; float newDist = spacing(event); float scale = newDist / oldDist; currentScale = (scale > 3.5f) ? 3.5f : scale; System.out.println("缩放倍数---" + currentScale); System.out.println("旋转角度---" + rotation); /** 縮放 */ matrix1.postScale(currentScale, currentScale, pointM.x, pointM.y); /** 旋轉 */ matrix1.postRotate(rotation, displayWidth / 2, displayHeight / 2); break; } } /** * 两个触点的距离 * * @param event 触摸事件 * @return float */ private float spacing(MotionEvent event) { float x = event.getX(0) - event.getX(1); float y = event.getY(0) - event.getY(1); return (float) Math.sqrt(x * x + y * y); } /** * 获取旋转角度 */ private float rotation(MotionEvent event) { double delta_x = (event.getX(0) - event.getX(1)); double delta_y = (event.getY(0) - event.getY(1)); double radians = Math.atan2(delta_y, delta_x); return (float) Math.toDegrees(radians); } /** * 两个触点的中间坐标 * * @param pointM 中间坐标 * @param event 触摸事件 */ private void setMidPoint(PointF pointM, MotionEvent event) { float x = event.getX(0) + event.getY(1); float y = event.getY(0) + event.getY(1); pointM.set(x / 2, y / 2); } /** * 检查约束条件(缩放倍数) */ private void checkView() { if (currentScale > 1) { if (currentScale * matrixScale > maxScale) { matrix.postScale(maxScale / matrixScale, maxScale / matrixScale, pointM.x, pointM.y); matrixScale = maxScale; } else { matrix.postScale(currentScale, currentScale, pointM.x, pointM.y); matrixScale *= currentScale; } } else { if (currentScale * matrixScale else { matrix.postScale(currentScale, currentScale, pointM.x, pointM.y); matrixScale *= currentScale; } } } /** * 图片居中显示、判断旋转角度 小于（90 * x + 45）度图片旋转（90 * x）度 大于则旋转（90 * (x+1)） */ private void centerAndRotate() { RectF rect = new RectF(0, 0, imgWidth, imgHeight); matrix.mapRect(rect); float width = rect.width(); float height = rect.height(); float dx = 0; float dy = 0; if (width 2 - width / 2 - rect.left; } else if (rect.left > 0) { dx = -rect.left; } else if (rect.right if (height 2 - height / 2 - rect.top; } else if (rect.top > 0) { dy = -rect.top; } else if (rect.bottom if (rotation != 0) { int rotationNum = (int) (rotation / 90); float rotationAvai = new BigDecimal(rotation % 90).setScale(1, BigDecimal.ROUND_HALF_UP).floatValue(); float realRotation = 0; if (rotation > 0) { realRotation = rotationAvai > 45 ? (rotationNum + 1) * 90 : rotationNum * 90; } else if (rotation 0) { realRotation = rotationAvai 45 ? (rotationNum - 1) * 90 : rotationNum * 90; } System.out.println("realRotation: " + realRotation); matrix.postRotate(realRotation, displayWidth / 2, displayHeight / 2); rotation = 0; } } /** * 显示网络图片时使用 */ private class MyTask extends AsyncTaskFile, File, Bitmap> { Bitmap bitmap; String path; int scale = 1; long size; @Override protected Bitmap doInBackground(File... params) { // TODO Auto-generated method stub try { size = params[0].length(); path = params[0].getAbsolutePath(); BitmapFactory.Options options = new BitmapFactory.Options(); options.inJustDecodeBounds = true; BitmapFactory.decodeFile(path, options); scale = calculateInSampleSize(options, displayWidth, displayHeight); options.inJustDecodeBounds = false; options.inSampleSize = scale; bitmap = BitmapFactory.decodeFile(path, options); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } return bitmap; } @Override protected void onPostExecute(Bitmap result) { // TODO Auto-generated method stub EventBus.getDefault().post( new CustomEventBus(CustomEventBus.EventType.SHOW_PICTURE, result)); } /** * 获取图片缩放比例 * * @param paramOptions Options * @param paramInt1 宽 * @param paramInt2 高 * @return int */ private int calculateInSampleSize(BitmapFactory.Options paramOptions, int paramInt1, int paramInt2) { int i = paramOptions.outHeight; int j = paramOptions.outWidth; int k = 1; if ((i > paramInt2) || (j > paramInt1)) { int m = Math.round(i / paramInt2); int n = Math.round(j / paramInt1); k = m return k; } } } CustomEventBus.java package com.practice.noyet.rotatezoomimageview; /** * package: com.practice.noyet.rotatezoomimageview * Created by noyet on 2015/11/11. */ public class CustomEventBus { public EventType type; public Object obj; public CustomEventBus(EventType type, Object obj) { this.type = type; this.obj = obj; } enum EventType { SHOW_PICTURE } }