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加上抗鋸齒標誌。然後將Paint對象作爲參數傳給canvas的繪製方法。

paint.setAntiAlias(true);

 

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

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

 

      測試代碼如下：

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);

	}

}