Android View加载圆形图片且同时绘制圆形图片的外部边缘边线及边框：LayerDrawable实现
LayerDrawable实现的结果和附录文章1,2,3中的layer-list一致。我写个例子，这次使用LayerDrawable把附录文章4的功能再次实现走通一遍。
写一个布局，简单放一个正方形的View：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/darker_gray"
android:orientation="vertical">
<View
android:id="@+id/view"
android:layout_width="300dp"
android:layout_height="300dp"
android:layout_centerInParent="true" />
</RelativeLayout>
然后在上层写Java代码：
package zhangphil.app;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.LayerDrawable;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.OvalShape;
import android.support.v4.graphics.drawable.RoundedBitmapDrawable;
import android.support.v4.graphics.drawable.RoundedBitmapDrawableFactory;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
int width = 50;
//最外部的白色环形边框
OvalShape ovalShape0 = new OvalShape();
ShapeDrawable drawable0 = new ShapeDrawable(ovalShape0);
drawable0.getPaint().setColor(Color.WHITE);
drawable0.getPaint().setStyle(Paint.Style.FILL);
drawable0.getPaint().setAntiAlias(true);
drawable0.getPaint().setStrokeWidth(width);
//黄色边框
OvalShape ovalShape1 = new OvalShape();
ShapeDrawable drawable1 = new ShapeDrawable(ovalShape1);
drawable1.getPaint().setColor(Color.YELLOW);
drawable1.getPaint().setStyle(Paint.Style.FILL);
drawable1.getPaint().setAntiAlias(true);
drawable1.getPaint().setStrokeWidth(width);
//红色边框
OvalShape ovalShape2 = new OvalShape();
ShapeDrawable drawable2 = new ShapeDrawable(ovalShape2);
drawable2.getPaint().setColor(Color.RED);
drawable2.getPaint().setStyle(Paint.Style.FILL);
drawable2.getPaint().setAntiAlias(true);
drawable2.getPaint().setStrokeWidth(width);
//最里面的图像
RoundedBitmapDrawable drawable3 = RoundedBitmapDrawableFactory.create(getResources(), BitmapFactory.decodeResource(getResources(), R.drawable.zhangphil));
drawable3.setCircular(true);
drawable3.setAntiAlias(true);
Drawable[] layers = new Drawable[4];
layers[0] = drawable0;
layers[1] = drawable1;
layers[2] = drawable2;
layers[3] = drawable3;
LayerDrawable layerDrawable = new LayerDrawable(layers);
//针对每一个图层进行填充，使得各个圆环之间相互有间隔，否则就重合成一个了。
layerDrawable.setLayerInset(0, width, width, width, width);
layerDrawable.setLayerInset(1, width * 2, width * 2, width * 2, width * 2);
layerDrawable.setLayerInset(2, width * 3, width * 3, width * 3, width * 3);
layerDrawable.setLayerInset(3, width * 4, width * 4, width * 4, width * 4);
final View view = findViewById(R.id.view);
view.setBackgroundDrawable(layerDrawable);
}
}
代码运行结果：
最里面的图像是我csdn博客的头像。
需要注意的是，我在写xml布局时候，特意写了一个正方形的View，假设这个View不是正方形，那么在上层java代码中使用OvalShape绘制图形则会因为屏幕的宽高变化成为椭圆而非圆。因此，作为一点儿经验，如果要在项目开发中制作圆形，务必保持正方形的宽高比。
附录：
1，《Android layer-list（1）》链接地址：http://blog.csdn.net/zhangphil/article/details/517209244
2，《Android layer-list：联合shape（2）》链接地址：http://blog.csdn.net/zhangphil/article/details/51721283
3，《Android layer-list（3）》链接地址：http://blog.csdn.net/zhangphil/article/details/51721816
4，《Android ImageView加载圆形图片且同时绘制圆形图片的外部边缘边线及边框》链接地址：http://blog.csdn.net/zhangphil/article/details/51944262
5，《Android ShapeDrawable之OvalShape、RectShape、PaintDrawable、ArcShape》链接地址：http://blog.csdn.net/zhangphil/article/details/52025152
6，《Android RoundedBitmapDrawable：Android官方的圆角图形图象实现方案》链接地址：http://blog.csdn.net/zhangphil/article/details/51829650
