android自定义一圆角ImageView

java类如下：

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.widget.ImageView;
import cn.dotcreate.tt.R;

public class RoundAngleImageView extends ImageView {

private Paint paint;
private int roundWidth = 5;
private int roundHeight = 5;
private Paint paint2;

public RoundAngleImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context, attrs);
}

public RoundAngleImageView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context, attrs);
}

public RoundAngleImageView(Context context) {
super(context);
init(context, null);
}

private void init(Context context, AttributeSet attrs) {

if(attrs != null) {
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.RoundAngleImageView);
roundWidth= a.getDimensionPixelSize(R.styleable.RoundAngleImageView_roundWidth, roundWidth);
roundHeight= a.getDimensionPixelSize(R.styleable.RoundAngleImageView_roundHeight, roundHeight);
}else {
float density = context.getResources().getDisplayMetrics().density;
roundWidth = (int) (roundWidth*density);
roundHeight = (int) (roundHeight*density);
}

paint = new Paint();
paint.setColor(Color.WHITE);
paint.setAntiAlias(true);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));

paint2 = new Paint();
paint2.setXfermode(null);
}

@Override
public void draw(Canvas canvas) {
Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Config.ARGB_8888);
Canvas canvas2 = new Canvas(bitmap);
super.draw(canvas2);
drawLiftUp(canvas2);
drawRightUp(canvas2);
drawLiftDown(canvas2);
drawRightDown(canvas2);
canvas.drawBitmap(bitmap, 0, 0, paint2);
bitmap.recycle();
}

private void drawLiftUp(Canvas canvas) {
Path path = new Path();
path.moveTo(0, roundHeight);
path.lineTo(0, 0);
path.lineTo(roundWidth, 0);
path.arcTo(new RectF(
0,
0,
roundWidth*2,
roundHeight*2),
-90,
-90);
path.close();
canvas.drawPath(path, paint);
}

private void drawLiftDown(Canvas canvas) {
Path path = new Path();
path.moveTo(0, getHeight()-roundHeight);
path.lineTo(0, getHeight());
path.lineTo(roundWidth, getHeight());
path.arcTo(new RectF(
0,
getHeight()-roundHeight*2,
0+roundWidth*2,
getHeight()),
90,
90);
path.close();
canvas.drawPath(path, paint);
}

private void drawRightDown(Canvas canvas) {
Path path = new Path();
path.moveTo(getWidth()-roundWidth, getHeight());
path.lineTo(getWidth(), getHeight());
path.lineTo(getWidth(), getHeight()-roundHeight);
path.arcTo(new RectF(
getWidth()-roundWidth*2,
getHeight()-roundHeight*2,
getWidth(),
getHeight()), 0, 90);
path.close();
canvas.drawPath(path, paint);
}

private void drawRightUp(Canvas canvas) {
Path path = new Path();
path.moveTo(getWidth(), roundHeight);
path.lineTo(getWidth(), 0);
path.lineTo(getWidth()-roundWidth, 0);
path.arcTo(new RectF(
getWidth()-roundWidth*2,
0,
getWidth(),
0+roundHeight*2),
-90,
90);
path.close();
canvas.drawPath(path, paint);
}

}

定义一个attr.xml的文件，放在values目录下面，内容如下：

<?xml version="1.0" encoding="utf-8"?>

<resources>

<declare-styleable name="RoundAngleImageView">

<attr name="roundWidth" format="dimension" />

<attr name="roundHeight" format="dimension" />

</declare-styleable>

</resources>

使用示例如下：

先要声明属性的名字空间：



然后再写跟一般定义View一样：
<cn.dotcreate.tt.ui.RoundAngleImageView

android:id="@+id/headIV"

android:layout_width="75dp"

android:layout_height="75dp"

android:layout_centerVertical="true"

android:layout_marginLeft="2dp"

app:roundWidth="10dp"

app:roundHeight="10dp"

android:src="@drawable/default_head_icon" />

效果如图：