自定义属性和圆环的绘制

1.设置自定义属性首先要在Values里面创建文件文件名为attrs.xml

<resources>
    <declare-styleable name="AnnulusView">
        <attr name="aaa" format="color"></attr>
    </declare-styleable>
</resources>

2.创建自定义组建类

AnnulusView

public class AnnulusView extends View {

    public int radius;
    public int widths;
    public String colors = "#ff0000";
    private Paint mPaint;
    private int color;

    public AnnulusView(Context context) {
        super(context);
    }

    public AnnulusView(Context context, AttributeSet attrs) {

        super(context, attrs);
        TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.AnnulusView);
        this.color = array.getColor(R.styleable.AnnulusView_aaa, Color.RED);

        //抗锯齿
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        //设置圆环
        mPaint.setStyle(Paint.Style.STROKE);


    }

    @Override
    protected void onDraw(Canvas canvas) {
        //设置画笔颜色
        mPaint.setColor(color);
    //设置圆环宽度
        mPaint.setStrokeWidth(widths);
    //设置圆的启示位置和半径
        canvas.drawCircle(300, 300, radius, mPaint);


    }

}

3.在mian.xml里面引用部件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
   >

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#ff0000"
        android:gravity="center"
        android:padding="5dp"
        android:text="自定义圆环"
        android:textColor="#ffffff"
        android:textSize="25sp" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:layout_marginTop="10dp"
        android:orientation="horizontal" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:padding="10dp"
            android:text="圆环的半径:"
            android:textSize="20sp" />

        <EditText
            android:id="@+id/et_radius"
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:textSize="20sp" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:layout_marginTop="10dp"
        android:orientation="horizontal" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:padding="10dp"
            android:text="圆环的宽度:"
            android:textSize="20sp" />

        <EditText
            android:id="@+id/et_width"
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:textSize="20sp" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:layout_marginTop="10dp"
        android:orientation="horizontal" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:padding="10dp"
            android:text="圆环的颜色:"
            android:textSize="20sp" />

        <EditText
            android:id="@+id/et_color"
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:textSize="20sp" />
    </LinearLayout>

    <Button
        android:id="@+id/bt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:background="#ff0000"
        android:gravity="center"
        android:padding="5dp"
        android:text="生成圆环展示"
        android:textColor="#ffffff"
        android:textSize="25sp" />

    <com.bawei.yuanhuan1.AnnulusView
        xmlns:custom="http://schemas.android.com/apk/res-auto"
        android:id="@+id/cv"
        custom:aaa="#f0f"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

4.在主activity写代码为:

public class MainActivity extends AppCompatActivity {

    private EditText etRadius;
    private EditText etWidth;
    private EditText etColor;
    private Button bt;
    private AnnulusView cv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 找到控件
        this.getWindowManager().getDefaultDisplay().getWidth();
        etRadius = (EditText) findViewById(R.id.et_radius);
        etWidth = (EditText) findViewById(R.id.et_width);
        etColor = (EditText) findViewById(R.id.et_color);
        bt = (Button) findViewById(R.id.bt);
        cv = (AnnulusView) findViewById(R.id.cv);
        bt.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                String radius = etRadius.getText().toString();
                String widths = etWidth.getText().toString();
                String colors = etColor.getText().toString();
                cv.radius = Integer.parseInt(radius);
                cv.widths = Integer.parseInt(widths);
                cv.colors = colors;
                cv.invalidate();


            }

        });


    }
}