android 图片的平移,缩放跟旋转

package com.example.yanlei.yl;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Matrix;import android.graphics.PointF;import android.util.DisplayMetrics;import android.util.FloatMath;import android.view.MotionEvent;import android.widget.ImageView;//自定义MyView类继承自ImageViewpublic class MyView extends ImageView {    private float x_down = 0;    private float y_down = 0;    //起始点的坐标    private PointF start = new PointF();    //中心点的坐标    private PointF mid = new PointF();    private float oldDist = 1f;    private float oldRotation = 0;    private Matrix matrix = new Matrix();    private Matrix matrix1 = new Matrix();    private Matrix savedMatrix = new Matrix();    private static final int NONE = 0;    private static final int DRAG = 1;    private static final int ZOOM = 2;    private int mode = NONE;    private boolean matrixCheck = false;    //记录当前屏幕的宽度    private int widthScreen;    //记录当前屏幕的高度    private int heightScreen;    //在页面中显示的Bitmap图片    private Bitmap kenan;    public MyView(Activity activity) {        super(activity);        //通过Bitampfactory读取drawable目录下的kenan资源        kenan = BitmapFactory.                decodeResource(getResources(), R.drawable.kenan);        //定义图片一个显示矩阵        DisplayMetrics dm = new DisplayMetrics();        //得到当前屏幕的显示矩阵存入dm变量        activity.getWindowManager().                getDefaultDisplay().getMetrics(dm);        //通过显示矩阵得到当前屏幕的宽度和高度的像素值        widthScreen = dm.widthPixels;        heightScreen = dm.heightPixels;        matrix = new Matrix();    }    //显示view的时候回调onDraw    protected void onDraw(Canvas canvas) {        //首先保存当前页面已有的图像        canvas.save();        //按照当前的矩阵绘制kenan图片        canvas.drawBitmap(kenan, matrix, null);        //画图板恢复        canvas.restore();    }    //当用户触摸此视图的时候回调次方法    public boolean onTouchEvent(MotionEvent event) {        //得到touch的事件类型        switch (event.getAction() & MotionEvent.ACTION_MASK) {            case MotionEvent.ACTION_DOWN:                //当按下屏幕时，记录当前的状态为拖动                mode = DRAG;                //记录xy坐标                x_down = event.getX();                y_down = event.getY();                //保存当前的矩阵                savedMatrix.set(matrix);                break;            case MotionEvent.ACTION_POINTER_DOWN:                //多个手指触摸的状态                mode = ZOOM;                //记录之前的两手指间距                oldDist = spacing(event);                //记录之前的角度                oldRotation = rotation(event);                //保存当前的图片矩阵                savedMatrix.set(matrix);                //得到旋转的中心点                midPoint(mid, event);                break;            case MotionEvent.ACTION_MOVE:                //当手指移动时的状态                if (mode == ZOOM) {                    //缩放并且平移                    matrix1.set(savedMatrix);                    //得到旋转的角度                    float rotation =                            rotation(event) - oldRotation;                    //得到距离                    float newDist = spacing(event);                    //得到放大倍数                    float scale = newDist / oldDist;                    //缩放倍数                    matrix1.postScale(scale, scale, mid.x, mid.y);                    //得到旋转角度                    matrix1.postRotate(rotation, mid.x, mid.y);                    //得到图片是否出边界                    matrixCheck = matrixCheck();                    if (matrixCheck == false) {                        matrix.set(matrix1);                        invalidate();                    }                } else if (mode == DRAG) {                    //平行移动                    matrix1.set(savedMatrix);                    matrix1.postTranslate(event.getX() - x_down                            , event.getY() - y_down);// 平移                    matrixCheck = matrixCheck();                    matrixCheck = matrixCheck();                    if (matrixCheck == false) {                        matrix.set(matrix1);                        invalidate();                    }                }                break;            case MotionEvent.ACTION_UP:            case MotionEvent.ACTION_POINTER_UP:                mode = NONE;                break;        }        return true;    }    //对图片的矩阵进行检测    private boolean matrixCheck() {        float[] f = new float[9];        matrix1.getValues(f);        // 图片4个顶点的坐标        float x1 = f[0] * 0 + f[1] * 0 + f[2];        float y1 = f[3] * 0 + f[4] * 0 + f[5];        float x2 = f[0] * kenan.getWidth()                + f[1] * 0 + f[2];        float y2 = f[3] * kenan.getWidth()                + f[4] * 0 + f[5];        float x3 = f[0] * 0 + f[1] *                kenan.getHeight() + f[2];        float y3 = f[3] * 0 + f[4] *                kenan.getHeight() + f[5];        float x4 = f[0] * kenan.getWidth() +                f[1] * kenan.getHeight() + f[2];        float y4 = f[3] * kenan.getWidth() +                f[4] * kenan.getHeight() + f[5];        // 图片现宽度        double width = Math.sqrt((x1 - x2) *                (x1 - x2) + (y1 - y2) * (y1 - y2));        // 缩放比率判断        if (width < widthScreen / 3 || width > widthScreen * 3) {            return true;        }        // 出界判断        if ((x1 < widthScreen / 3 && x2 < widthScreen / 3                && x3 < widthScreen / 3                && x4 < widthScreen / 3)                || (x1 > widthScreen * 2 / 3                && x2 > widthScreen * 2 / 3                && x3 > widthScreen * 2 / 3                && x4 > widthScreen * 2 / 3)                || (y1 < heightScreen / 3                && y2 < heightScreen / 3                && y3 < heightScreen / 3                && y4 < heightScreen / 3)                || (y1 > heightScreen * 2 / 3                && y2 > heightScreen * 2 / 3                && y3 > heightScreen * 2 / 3                && y4 > heightScreen * 2 / 3)) {            return true;        }        return false;    }    // 触碰两点间距离    private float spacing(MotionEvent event) {        //通过三角函数得到两点间的距离        float x = event.getX(0) - event.getX(1);        float y = event.getY(0) - event.getY(1);        return FloatMath.sqrt(x * x + y * y);    }    // 取手势中心点    private void midPoint(PointF point, MotionEvent event) {        //得到手势中心点的位置        float x = event.getX(0) + event.getX(1);        float y = event.getY(0) + event.getY(1);        point.set(x / 2, y / 2);    }    // 取旋转角度    private float rotation(MotionEvent event) {        //得到两个手指间的旋转角度        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);    }}