CircleDrawable.java

package org.rocko.demos.colorfilter;

import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.ColorFilter;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.Shader;
import android.graphics.drawable.Drawable;

/**
 * Created by Rocko on 2015/3/2 19:30
 */
public class CircleDrawable extends Drawable {

    private Paint mPaint;
    private int mWidth;
    private Bitmap mBitmap;

    public CircleDrawable(Bitmap bitmap) {
        this.mBitmap = bitmap;
        BitmapShader bitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP,
                Shader.TileMode.CLAMP);
        this.mPaint = new Paint();
        this.mPaint.setAntiAlias(true);
        this.mPaint.setShader(bitmapShader);
        this.mWidth = Math.min(mBitmap.getWidth(), mBitmap.getHeight());
    }

    @Override
    public void draw(Canvas canvas) {
        canvas.drawCircle(mWidth >> 1, mWidth >> 1, mWidth >> 1, mPaint);
    }

    @Override
    public int getIntrinsicWidth() {
        return mWidth;
    }

    @Override
    public int getIntrinsicHeight() {
        return mWidth;
    }

    @Override
    public void setAlpha(int alpha) {
        mPaint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(ColorFilter cf) {
        mPaint.setColorFilter(cf);
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;
    }
}