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