Android自定义ImageView实现圆角功能

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <declare-styleable name="roundcornerimageview">
    <attr name="radius" format="dimension" />
    <attr name="left_top_radius" format="dimension" />
    <attr name="right_top_radius" format="dimension" />
    <attr name="right_bottom_radius" format="dimension" />
    <attr name="left_bottom_radius" format="dimension" />
  </declare-styleable>
</resources>

public class roundcornerimageview extends appcompatimageview {
  private float width, height;
  private int defaultradius = 0;
  private int radius;
  private int lefttopradius;
  private int righttopradius;
  private int rightbottomradius;
  private int leftbottomradius;


  public roundcornerimageview(context context) {
    this(context, null);
    init(context, null);
  }

  public roundcornerimageview(context context, attributeset attrs) {
    this(context, attrs, 0);
    init(context, attrs);
  }

  public roundcornerimageview(context context, attributeset attrs, int defstyleattr) {
    super(context, attrs, defstyleattr);
    init(context, attrs);
  }

  private void init(context context, attributeset attrs) {
    if (build.version.sdk_int < 18) {
      setlayertype(view.layer_type_software, null);
    }
    // 读取配置
    typedarray array = context.obtainstyledattributes(attrs, r.styleable.roundcornerimageview);
    radius = array.getdimensionpixeloffset(r.styleable.roundcornerimageview_radius, defaultradius);
    lefttopradius = array.getdimensionpixeloffset(r.styleable.roundcornerimageview_left_top_radius, defaultradius);
    righttopradius = array.getdimensionpixeloffset(r.styleable.roundcornerimageview_right_top_radius, defaultradius);
    rightbottomradius = array.getdimensionpixeloffset(r.styleable.roundcornerimageview_right_bottom_radius, defaultradius);
    leftbottomradius = array.getdimensionpixeloffset(r.styleable.roundcornerimageview_left_bottom_radius, defaultradius);


    //如果四个角的值没有设置，那么就使用通用的radius的值。
    if (defaultradius == lefttopradius) {
      lefttopradius = radius;
    }
    if (defaultradius == righttopradius) {
      righttopradius = radius;
    }
    if (defaultradius == rightbottomradius) {
      rightbottomradius = radius;
    }
    if (defaultradius == leftbottomradius) {
      leftbottomradius = radius;
    }
    array.recycle();
  }


  @override
  protected void onlayout(boolean changed, int left, int top, int right, int bottom) {
    super.onlayout(changed, left, top, right, bottom);
    width = getwidth();
    height = getheight();
  }

  @override
  protected void ondraw(canvas canvas) {
    //这里做下判断，只有图片的宽高大于设置的圆角距离的时候才进行裁剪
    int maxleft = math.max(lefttopradius, leftbottomradius);
    int maxright = math.max(righttopradius, rightbottomradius);
    int minwidth = maxleft + maxright;
    int maxtop = math.max(lefttopradius, righttopradius);
    int maxbottom = math.max(leftbottomradius, rightbottomradius);
    int minheight = maxtop + maxbottom;
    if (width >= minwidth && height > minheight) {
      path path = new path();
      //四个角：右上，右下，左下，左上
      path.moveto(lefttopradius, 0);
      path.lineto(width - righttopradius, 0);
      path.quadto(width, 0, width, righttopradius);

      path.lineto(width, height - rightbottomradius);
      path.quadto(width, height, width - rightbottomradius, height);

      path.lineto(leftbottomradius, height);
      path.quadto(0, height, 0, height - leftbottomradius);

      path.lineto(0, lefttopradius);
      path.quadto(0, 0, lefttopradius, 0);

      canvas.clippath(path);
    }
    super.ondraw(canvas);
  }

}

<?xml version="1.0" encoding="utf-8"?>
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical"
  tools:context="voicedemo.iflytek.com.roundimage.mainactivity">

  <voicedemo.iflytek.com.roundimage.roundcornerimageview
    android:id="@+id/iv_avatar"
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:layout_marginbottom="10dp"
    android:layout_margintop="50dp"
    android:scaletype="centercrop"
    app:left_top_radius="20dp"
    app:right_top_radius="20dp"
    />
</linearlayout>

public class mainactivity extends appcompatactivity {

  string avatarurl = "19e9d4c0a8f1cd033ecac3692_th.jpg";

  @override
  protected void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.activity_main);

    imageview ivavatar = findviewbyid(r.id.iv_avatar);

    glide.with(this).load(avatarurl).into(ivavatar);

  }
}