Android畫圖之抗鋸齒

在畫圖的時候，圖片如果旋轉或縮放之後，總是會出現那些華麗的鋸齒。其實android自帶了解決方式。 

方法一：給Paint加上抗鋸齒標志。然後將Paint對象作為參數傳給canvas的繪制方法。 
Java代碼

1. paint.setAntiAlias(true);  
    
2. 
    
3. paint.setAntiAlias(true);

方法二：給Canvas加上抗鋸齒標志。 
有些地方不能用paint的，就直接給canvas加抗鋸齒，更方便。  

Java代碼

1. canvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG));  
    
2. 
    
3. canvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG));
    

測試代碼如下：  

Java代碼

1. import android.content.Context;   
    
2. import android.graphics.Bitmap;   
    
3. import android.graphics.BitmapFactory;   
    
4. import android.graphics.Canvas;   
    
5. import android.graphics.Matrix;   
    
6. import android.graphics.Paint;   
    
7. import android.graphics.PaintFlagsDrawFilter;   
    
8. import android.view.VIEw;   
    
9.    
    
10. public class MyView extends VIEw {   
     
11.     private PaintFlagsDrawFilter pfd;   
     
12.     private Paint mPaint = new Paint();   
     
13.     private Matrix matrix = new Matrix();;   
     
14.     private Bitmap bmp;   
     
15.    
     
16.     public MyVIEw(Context context) {   
     
17.         super(context);   
     
18.         initialize();   
     
19.     }   
     
20.    
     
21.     private void initialize() {   
     
22.         pfd = new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG);         
     
23.         mPaint.setAntiAlias(true);   
     
24.         matrix.setRotate(30);   
     
25.         matrix.postScale(0.5f, 0.5f);   
     
26.         bmp = BitmapFactory.decodeResource(getResources(), R.drawable.show);   
     
27.     }   
     
28.         
     
29.     @Override  
     
30.     public void dispatchDraw(Canvas canvas) {   
     
31.         canvas.translate(100, 0);   
     
32.         canvas.drawBitmap(bmp, matrix, null);   
     
33.         canvas.translate(0, 250);   
     
34.         canvas.drawBitmap(bmp, matrix, mPaint);   
     
35.         canvas.setDrawFilter(pfd);   
     
36.         canvas.translate(0, 250);   
     
37.         canvas.drawBitmap(bmp, matrix, null);   
     
38.     }   
     
39. }