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Android Xfermode 学习笔记

发布时间:2016-03-27 19:00:20
一、概述Xfermode全名transfer-mode,其作用是实现两张图叠加时的混合效果。网上流传的关于Xfermode最出名的图来源于AndroidSDK的samples中,名叫Xfermodes.java,效果如下: [转载请保留本文地址:http://www.c ...

Android Xfermode 学习笔记

一、概述

Xfermode全名transfer-mode,其作用是实现两张图叠加时的混合效果。

网上流传的关于Xfermode最出名的图来源于AndroidSDK的samples中,名叫Xfermodes.java,效果如下:

Android Xfermode 学习笔记

  [转载请保留本文地址:http://www.cnblogs.com/goagent/p/5326438.html]  

二、体验

提炼出Xfermodes.java中的核心代码,自己写了个简单粗暴的demo试试水:

 1 public class ImageViewXfermode extends ImageView { 2   public ImageViewXfermode(Context context) { 3     super(context); 4     init(); 5   } 6  7   public ImageViewXfermode(Context context, AttributeSet attrs) { 8     super(context, attrs); 9     init();10   }11 12   public ImageViewXfermode(Context context, AttributeSet attrs, int defStyle) {13     super(context, attrs, defStyle);14     init();15   }16   17   private void init() {18     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {19       setLayerType(View.LAYER_TYPE_SOFTWARE, null);20     }21   }22   23   @Override24   protected void onDraw(Canvas canvas) {25     int defaultWidth = dip2px(85); //26     int defaultdHeight = dip2px(85); //27 28     if (canvas.getHeight() == defaultWidth && canvas.getHeight() == defaultdHeight) {29       //拿到黄色圆形的bitmap30       Bitmap bitcircle = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);31       Canvas canvascicle = new Canvas(bitcircle);32       Paint paintcicle = new Paint(Paint.ANTI_ALIAS_FLAG);33       paintcicle.setColor(0xFFFFCC44);34       canvascicle.drawCircle(dip2px(30), dip2px(30), dip2px(25), paintcicle);35       36       //拿到蓝色矩形的bitmap37       Bitmap bitrect = Bitmap.createBitmap(defaultWidth, defaultdHeight, Config.ARGB_8888);38       Canvas canvasrect = new Canvas(bitrect);39       Paint paintrect = new Paint(Paint.ANTI_ALIAS_FLAG);40       paintrect.setColor(0xFF66AAFF);41       canvasrect.drawRect(dip2px(30), dip2px(30), dip2px(80), dip2px(80), paintrect);42       43       Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);44       Xfermode xfermode = new PorterDuffXfermode(Mode.LIGHTEN);45       46       //采用saveLayer,让后续canvas的绘制在自动创建的bitmap上47       int cnt = canvas.saveLayer(0, 0, defaultWidth, defaultdHeight, null, Canvas.ALL_SAVE_FLAG);48       //先画圆形,圆形是dest49       canvas.drawBitmap(bitcircle, 0, 0, paint);50       paint.setXfermode(xfermode);51       //后画矩形,矩形是src52       canvas.drawBitmap(bitrect, 0, 0, paint);53       paint.setXfermode(null);54       canvas.restoreToCount(cnt);55     } else {56       super.onDraw(canvas);57     }58   }59   60   private int dip2px(float dip) {61     float scale = getResources().getDisplayMetrics().density;62     return (int)(dip * scale + 0.5f);63   }64 }

原标题:Android Xfermode 学习笔记

关键词:Android

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