PorterDuffXfermode之PorterDuff.Mode.LIGHTEN

package com.loaderman.customviewdemo.view;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.util.AttributeSet;
import android.view.View;

import com.loaderman.customviewdemo.R;

public class LightBookView extends View {
    private Paint mBitPaint;
    private Bitmap BmpDST,BmpSRC;

    public LightBookView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mBitPaint = new Paint();
        BmpDST = BitmapFactory.decodeResource(getResources(), R.drawable.book_bg, null);
        BmpSRC = BitmapFactory.decodeResource(getResources(),R.drawable.book_light,null);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        canvas.save();

        canvas.drawBitmap(BmpDST,0,0,mBitPaint);
        mBitPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.LIGHTEN));
        canvas.drawBitmap(BmpSRC,0,0,mBitPaint);

        mBitPaint.setXfermode(null);
        canvas.restore();
    }
}

  <com.loaderman.customviewdemo.view.LightBookView
      android:layout_width="match_parent"
      android:layout_height="match_parent" />

效果图: