Android学习笔记之详细讲解画圆角图片

01package xiaosi.RoundConcer;

02 

03import android.app.Activity;

04import android.graphics.Bitmap;

05import android.graphics.Bitmap.Config;

06import android.graphics.BitmapFactory;

07import android.graphics.Canvas;

08import android.graphics.Paint;

09import android.graphics.PorterDuff.Mode;

10import android.graphics.PorterDuffXfermode;

11import android.graphics.Rect;

12import android.graphics.RectF;

13import android.os.Bundle;

14import android.widget.ImageView;

15 

16public class RoundConcerActivity extends Activity

17{

18    /** Called when the activity is first created. */

19    private ImageView roundImage = null;

20    @Override

21    public void onCreate(Bundle savedInstanceState)

22    {

23        super.onCreate(savedInstanceState);

24        setContentView(R.layout.main);

25         

26        roundImage = (ImageView)findViewById(R.id.roundconcer);

27         

28         

29        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.a);

30        roundImage.setImageBitmap(getRoundCornerImage(bitmap, 50));

31    }

32 

33    public static Bitmap getRoundCornerImage(Bitmap bitmap, int roundPixels)

34    {

35        //创建一个和原始图片一样大小位图

36        Bitmap roundConcerImage = Bitmap.createBitmap(bitmap.getWidth(),

37                bitmap.getHeight(), Config.ARGB_8888);

38        //创建带有位图roundConcerImage的画布

39        Canvas canvas = new Canvas(roundConcerImage);

40        //创建画笔

41        Paint paint = new Paint();

42        //创建一个和原始图片一样大小的矩形

43        Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());

44        RectF rectF = new RectF(rect);

45        // 去锯齿

46        paint.setAntiAlias(true);

47        //画一个和原始图片一样大小的圆角矩形

48        canvas.drawRoundRect(rectF, roundPixels, roundPixels, paint);

49        //设置相交模式

50        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));

51        //把图片画到矩形去

52        canvas.drawBitmap(bitmap, null, rect, paint);

53        return roundConcerImage;

54    }

55}