Android画图之抗锯齿

转自http://chroya.javaeye.com/blog/794505

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：

 

      可以看出，两种方式都挺有效的。