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); 

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)); 

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);  
    }  
} 

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);
 }
}

转http://blog.sina.com.cn/s/blog_5fc933730100qmg8.html