一个简单的Loading控件

实现效果如下：

使用方法：

在layout文件中添加以下代码：

   <com.example.jack.ui.widget.RingLoading

        android:layout_width="20.0dip"

        android:layout_height="20.0dip"

   />

具体代码如下：

package com.example.jack.ui.widget;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Matrix;

import android.graphics.Paint;

import android.graphics.SweepGradient;

import android.util.AttributeSet;

import android.view.View;

/**

 * Created by pengf on 2017/4/10.

 */

public class RingLoading extends View

{

    private static final int PROGRESS = 5;

    private int centerX;

    private int centerY;

    private Context context;

    private int mProgressColor ;

    private Matrix matrix;

    private final Paint paint;

    private int roundWidth = 10;

    private int start = 0;

    public RingLoading(Context context, AttributeSet attrs)

    {

        super(context, attrs);

        this.context = context;

        this.paint = new Paint();

        this.paint.setAntiAlias(true);

        this.paint.setStyle(Paint.Style.STROKE);

        this.paint.setStrokeWidth(this.roundWidth);

        this.mProgressColor =Color.parseColor("#ffffcc00");

    }

    @Override

    protected void onDraw(Canvas canvas)

    {

        int center = getWidth() / 2;

        int radius = center - this.roundWidth / 2;

        SweepGradient sweepGradient = new SweepGradient(this.centerX, this.centerY, Color.TRANSPARENT, this.mProgressColor);

        this.paint.setShader(sweepGradient);

        this.matrix = new Matrix();

        this.matrix.postRotate(this.start, this.centerX, this.centerY);

        canvas.concat(this.matrix);

        canvas.drawCircle(center, center, radius, this.paint);

        this.start = (PROGRESS + this.start);

        invalidate();

    }

    @Override

    protected void onSizeChanged(int w, int h, int oldw, int oldh)

    {

        super.onSizeChanged(w, h, oldw, oldh);

        this.centerX = (w / 2);

        this.centerY = (h / 2);

    }

}