Android画图之抗锯齿

 在画图的时候，图片如果旋转或缩放之后，总是会出现那些华丽的锯齿。其实Android自带了解决方式。
   

方法一：给Paint加上抗锯齿标志。然后将Paint对象作为参数传给canvas的绘制方法。

paint.setAntiAlias(true);  

 

方法二：给Canvas加上抗锯齿标志。

有些地方不能用paint的，就直接给canvas加抗锯齿，更方便。

 

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

 

测试代码如下：

import android.content.Context;  
import android.graphics.Bitmap;  
import android.graphics.BitmapFactory;  
import android.graphics.Canvas;  
import android.graphics.Matrix;  
import android.graphics.Paint;  
import android.graphics.PaintFlagsDrawFilter;  
import android.view.View;  
  
public class MyView extends View {  
    private PaintFlagsDrawFilter pfd;  
    private Paint mPaint = new Paint();  
    private Matrix matrix = new Matrix();;  
    private Bitmap bmp;  
  
    public MyView(Context context) {  
        super(context);  
        initialize();  
    }  
  
    private void initialize() {  
        pfd = new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG);        
        mPaint.setAntiAlias(true);  
        matrix.setRotate(30);  
        matrix.postScale(0.5f, 0.5f);  
        bmp = BitmapFactory.decodeResource(getResources(), R.drawable.show);  
    }  
      
    @Override  
    public void dispatchDraw(Canvas canvas) {  
        canvas.translate(100, 0);  
        canvas.drawBitmap(bmp, matrix, null);  
        canvas.translate(0, 250);  
        canvas.drawBitmap(bmp, matrix, mPaint);  
        canvas.setDrawFilter(pfd);  
        canvas.translate(0, 250);  
        canvas.drawBitmap(bmp, matrix, null);  
    }  
}  

 

下图是效果：