自定義View圓形加載器、變色、加速減速、開始暫停

效果：

首先在valus下創建attrs.xml文件:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="MyCustomCircleArrowView">
        <attr name="circlr_bound_width" format="dimension"></attr>
        <attr name="circlr_bound_color" format="color"></attr>
    </declare-styleable>

</resources>

繼承view：

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.View;
import android.widget.Toast;

/**
 * 類的作用和實現思路:自定義view
 * Created by 王 on 2017/10/9.
 */

public class WxyView extends View{
    //從xml中獲取的顏色
    private int circleBoundColor;
    private float circleBoundWidth;

    //當前畫筆畫圓的顏色
    private int CurrenCircleBoundColor;

    private Paint paint;

    public WxyView(Context context) {
        super(context);
        initVeiw(context);
    }


    public WxyView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        initVeiw(context);
        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.MyCustomCircleArrowView);
        for (int i = 0; i < typedArray.getIndexCount(); i++) {

            //就是我們自定義的屬性的資源id
            int attr = typedArray.getIndex(i);
            switch (attr) {
                case R.styleable.MyCustomCircleArrowView_circlr_bound_color:
                    circleBoundColor = typedArray.getColor(attr, Color.RED);
                    CurrenCircleBoundColor = circleBoundColor;
                    break;
                case R.styleable.MyCustomCircleArrowView_circlr_bound_width:
                    circleBoundWidth = typedArray.getDimension(attr, 3);
                    break;
            }
        }
    }

    private void initVeiw(Context context) {
        paint = new Paint();
    }

    public void setColor(int color) {
        if (CurrenCircleBoundColor != color) {
            CurrenCircleBoundColor = color;
        } else {
            CurrenCircleBoundColor = circleBoundColor;
        }
    }


    //圓心
    private float pivotX;
    private float pivotY;
    private float radius = 130;

    private float currentDegree = 0;

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        paint.setAntiAlias(true);
        paint.setColor(CurrenCircleBoundColor);
        paint.setStrokeWidth(circleBoundWidth);
        paint.setStyle(Paint.Style.STROKE);
        pivotX = getWidth() / 2;
        pivotY = getHeight() / 2;
        canvas.drawCircle(pivotX, pivotY, radius, paint);

        canvas.save();

        //旋轉畫布 , 如果旋轉的的度數大的話,視覺上看着是旋轉快的
        canvas.rotate(currentDegree, pivotX, pivotY);

        //提供了一些api可以用來畫線(畫路徑)
        Path path = new Path();

        //從哪開始畫 從A開始畫
        path.moveTo(pivotX + radius, pivotY);

        //從A點畫一個直線到D點
        path.lineTo(pivotX + radius - 20, pivotY - 20);

        //從D點畫一個直線到B點
        path.lineTo(pivotX + radius, pivotY + 20);

        //從B點畫一個直線到C點
        path.lineTo(pivotX + radius + 20, pivotY - 20);

        //閉合  --  從C點畫一個直線到A點
        path.close();
        paint.setStyle(Paint.Style.FILL);
        paint.setColor(Color.BLACK);
        canvas.drawPath(path, paint);
        canvas.restore();

        //旋轉的度數一個一個度數增加,  如果乘以一個速度的話,按一個速度速度增加
        currentDegree += 1 * currentSpeed;

        if (!isPause) {
            invalidate();
        }
    }

    private int currentSpeed = 1;
    private boolean isPause = false;

    public void speed() {
        ++currentSpeed;
        if (currentSpeed >= 10) {
            currentSpeed = 10;
            Toast.makeText(getContext(), "我比閃電還快", Toast.LENGTH_SHORT).show();
        }
    }

    public void slowDown() {
        --currentSpeed;
        if (currentSpeed <=1) {
            currentSpeed = 1;
        }
    }

    public void pauseOrStart() {

        //如果是開始狀態的話去重新繪製
        if (isPause) {
            isPause = !isPause;
            invalidate();
        } else {
            isPause = !isPause;
        }
    }

}

佈局：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
    tools:context="com.example.circulardemo.MainActivity">


    <Button
        android:id="@+id/set_color_btn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:onClick="onClick"
        android:text="設置顏色" />

    <Button
        android:id="@+id/add"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/set_color_btn"
        android:layout_centerHorizontal="true"
        android:onClick="add"
        android:text="加速" />

    <Button
        android:id="@+id/slow"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/add"
        android:layout_centerHorizontal="true"
        android:onClick="slow"
        android:text="減速" />

    <Button
        android:id="@+id/pause_or_start"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/slow"
        android:layout_centerHorizontal="true"
        android:onClick="pauseOrStart"
        android:text="暫定/開始" />

    <com.example.circulardemo.WxyView
        android:id="@+id/my_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        app:circlr_bound_color="@color/colorAccent"
        app:circlr_bound_width="3dp" />


</RelativeLayout>

Mainactivity:

import android.graphics.Color;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;

public class MainActivity extends AppCompatActivity {
    private WxyView myCustomCircleArrowView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        myCustomCircleArrowView = (WxyView) findViewById(R.id.my_view);
    }

    //設置顏色
    public void onClick(View view) {
        myCustomCircleArrowView.setColor(Color.BLUE);
    }

    public void add(View view) {
        myCustomCircleArrowView.speed();
    }

    public void slow(View view) {
        myCustomCircleArrowView.slowDown();
    }


    public void pauseOrStart(View view) {
        myCustomCircleArrowView.pauseOrStart();
    }
}

完成！