如何在android中缩放自定义图像视图？

在我的face detector项目中，我使用自定义ImageView（MyView）来检测人脸并在检测到的人脸上绘制矩形。为此，我为我的customview（MyView）设置了固定尺寸，并尝试缩放位图以适应customview。但不知何故，我无法做到这一点。 在这方面，我已经回答了所有类似的问题。请帮忙

activity_main.xml

<RelativeLayout  
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" 
tools:context=".MainActivity">


<com.sample.facedetector.MyView
    android:layout_width="300dp"
    android:layout_height="300dp"
    android:id="@+id/MyViewId"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="28dp"
    android:scaleType="centerCrop"/>

MyView

package com.sample.facedetector;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PointF;
import android.media.FaceDetector;
import android.support.annotation.DrawableRes;
import android.util.AttributeSet;
import android.widget.ImageView;

public class MyView extends ImageView {

private Bitmap mFaceBitmap;
private int count = 0;
private FaceDetector.Face[] faces;
private Bitmap image;

public MyView(Context context, AttributeSet attrs) {
    super(context, attrs);
}


public MyView(Context context) {
    super(context);
}
public MyView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
}

public void detectFaces(){

    FaceDetector myFaceDetector = null;
    mFaceBitmap = image.copy(Bitmap.Config.RGB_565, true);

    int targetWidth = mFaceBitmap.getWidth();
    int targetHeight = mFaceBitmap.getHeight();

    faces= new FaceDetector.Face[5];


    int[] fpx =null;
    int[] fpy = null;
    myFaceDetector = new FaceDetector(targetWidth,targetHeight,5);
    count = myFaceDetector.findFaces(mFaceBitmap, faces);
    setWillNotCacheDrawing(true);
    requestLayout();
    this.invalidate();
}

/*@Override
public void setScaleType(ScaleType scaleType) {
    super.setScaleType(ScaleType.CENTER);
    invalidate();
}*/

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    canvas.drawBitmap(mFaceBitmap,0,0,null);
    Paint myPaint = new Paint();
    myPaint.setColor(Color.GREEN);
    myPaint.setStyle(Paint.Style.STROKE);
    myPaint.setStrokeWidth(3);

    if (count > 0) {
        for (int i = 0; i < count; i++) {
            FaceDetector.Face face = faces[i];
            PointF midPoint = new PointF();
            face.getMidPoint(midPoint);
            float eyeDistance = face.eyesDistance();
            canvas.drawRect(midPoint.x-eyeDistance, midPoint.y-eyeDistance, midPoint.x+eyeDistance, midPoint.y+eyeDistance, myPaint);

        }
    }

}



@Override
public void setImageResource(@DrawableRes int resId) {
    super.setImageResource(resId);
    invalidate();
}

public void setImage(Bitmap image) {
    this.image = image;
}

package com.sample.facedetector；
导入android.content.Context；
导入android.graphics.Bitmap；
导入android.graphics.Canvas；
导入android.graphics.Color；
导入android.graphics.Paint；
导入android.graphics.PointF；
导入android.media.FaceDetector；
导入android.support.annotation.DrawableRes；
导入android.util.AttributeSet；
导入android.widget.ImageView；
公共类MyView扩展了ImageView{
私有位图；
私有整数计数=0；
私人面部检测器。面部[]面部；
私有位图图像；
公共MyView（上下文、属性集属性）{
超级（上下文，attrs）；
}
公共MyView（上下文）{
超级（上下文）；
}
公共MyView（上下文上下文、属性集属性、int-defStyle）{
超级（上下文、属性、定义样式）；
}
公共void detectFaces（）{
FaceDetector myFaceDetector=null；
mFaceBitmap=image.copy（Bitmap.Config.RGB_565，true）；
int targetWidth=MFACE位图.getWidth（）；
int-targetHeight=mFaceBitmap.getHeight（）；
面=新的面检测器。面[5]；
int[]fpx=null；
int[]fpy=null；
myFaceDetector=新的FaceDetector（targetWidth，targetLight，5）；
count=myFaceDetector.findFaces（MFACE位图，面）；
setWillNotCacheDrawing（真）；
requestLayout（）；
这个。使无效（）；
}
/*@凌驾
public void setScaleType（ScaleType ScaleType）{
super.setScaleType（ScaleType.CENTER）；
使无效（）；
}*/
@凌驾
受保护的void onDraw（画布）{
super.onDraw（帆布）；
drawBitmap（mFaceBitmap，0,0，null）；
绘制myPaint=新绘制（）；
myPaint.setColor（颜色.绿色）；
myPaint.setStyle（Paint.Style.STROKE）；
myPaint.设置行程宽度（3）；
如果（计数>0）{
for（int i=0；i

}

package com.sample.facedetector;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PointF;
import android.media.FaceDetector;
import android.support.annotation.DrawableRes;
import android.util.AttributeSet;
import android.widget.ImageView;

public class MyView extends ImageView {

private Bitmap mFaceBitmap;
private int count = 0;
private FaceDetector.Face[] faces;
private Bitmap image;

public MyView(Context context, AttributeSet attrs) {
    super(context, attrs);
}


public MyView(Context context) {
    super(context);
}
public MyView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
}

public void detectFaces(){

    FaceDetector myFaceDetector = null;
    mFaceBitmap = image.copy(Bitmap.Config.RGB_565, true);

    int targetWidth = mFaceBitmap.getWidth();
    int targetHeight = mFaceBitmap.getHeight();

    faces= new FaceDetector.Face[5];


    int[] fpx =null;
    int[] fpy = null;
    myFaceDetector = new FaceDetector(targetWidth,targetHeight,5);
    count = myFaceDetector.findFaces(mFaceBitmap, faces);
    setWillNotCacheDrawing(true);
    requestLayout();
    this.invalidate();
}

/*@Override
public void setScaleType(ScaleType scaleType) {
    super.setScaleType(ScaleType.CENTER);
    invalidate();
}*/

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    canvas.drawBitmap(mFaceBitmap,0,0,null);
    Paint myPaint = new Paint();
    myPaint.setColor(Color.GREEN);
    myPaint.setStyle(Paint.Style.STROKE);
    myPaint.setStrokeWidth(3);

    if (count > 0) {
        for (int i = 0; i < count; i++) {
            FaceDetector.Face face = faces[i];
            PointF midPoint = new PointF();
            face.getMidPoint(midPoint);
            float eyeDistance = face.eyesDistance();
            canvas.drawRect(midPoint.x-eyeDistance, midPoint.y-eyeDistance, midPoint.x+eyeDistance, midPoint.y+eyeDistance, myPaint);

        }
    }

}



@Override
public void setImageResource(@DrawableRes int resId) {
    super.setImageResource(resId);
    invalidate();
}

public void setImage(Bitmap image) {
    this.image = image;
}