android绘制圆形图片、圆圈以及图片缩放

这两天做开发，需要将图片资源做成圆形，并且要对图片进行缩放，研究了半天，终于整出来了，效果如下：

代码如下：

package com.android.mywidget;

import android.content.Context;

import android.graphics.*;

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.view.View;

import android.widget.ImageView;

import com.android.contacts.R;

import android.util.Log;

public class CircleImageView extends ImageView implements View.OnClickListener {

    private static final String TAG = "CircleImageView";

    private Paint mPaint = new Paint();

    private static final int STROKE_WIDTH = 8;

    public CircleImageView(Context context, AttributeSet attrs) {

        super(context, attrs);

    }

    protected void onFinishInflate() {

        super.onFinishInflate();

        setOnClickListener(this);

    }

    @Override

    protected void onDraw(Canvas canvas) {

        Drawable drawable = getDrawable();

        if (null != drawable) {

            Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();

            Bitmap b = circleBitmap(scaleBitmap(bitmap));

            final Rect rect = new Rect(0, 0, b.getWidth(), b.getHeight());

            mPaint.reset();

            canvas.drawBitmap(b, rect, rect, mPaint);

        } else {

            super.onDraw(canvas);

        }

    }

    // 将矩形图片绘制成圆形图片并在最外围画一圈白色

    private Bitmap circleBitmap(Bitmap bitmap) {

        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),

                bitmap.getHeight(), Config.ARGB_8888);

        Canvas canvas = new Canvas(output);

        final int color = 0xff000000;

        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());

        mPaint.setAntiAlias(true);

        canvas.drawARGB(0, 0, 0, 0);

        mPaint.setColor(color);

        final int width = bitmap.getWidth();

        canvas.drawCircle(width / 2, width / 2, width / 2, mPaint);

        mPaint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));

        canvas.drawBitmap(bitmap, rect, rect, mPaint);//将图片绘制成白色图片

        //画白色圆圈

        mPaint.reset();

        mPaint.setColor(Color.WHITE);

        mPaint.setStyle(Paint.Style.STROKE);

        mPaint.setStrokeWidth(STROKE_WIDTH);

        mPaint.setAntiAlias(true);

        canvas.drawCircle(width / 2, width / 2, width / 2 - STROKE_WIDTH / 2, mPaint);

        return output;

    }

    private Bitmap scaleBitmap(Bitmap src) {

        int width = src.getWidth();//原来尺寸大小

        int height = src.getHeight();

        final float destSize = this.getWidth();//缩放到这个大小

//图片缩放比例，新尺寸/原来的尺寸

        float scaleWidth = ((float) destSize) / width;

        float scaleHeight = ((float) destSize) / height;

        Matrix matrix = new Matrix();

        matrix.postScale(scaleWidth, scaleHeight);

//返回缩放后的图片

        return Bitmap.createBitmap(src, 0, 0, width, height, matrix, true);

    }

    @Override

    public void onClick(View v) {

        //To change body of implemented methods use File | Settings | File Templates.

    }

}