Android-自定义圆形ProgressBar加载

帮朋友做个圆形加载进度条，

后来发现做的挺简单的，大佬一个比一个厉害

介绍一下：

1.自定义View属性
2.View 的测量
3.计算绘制 View 所需参数
4.圆弧的绘制及渐变的实现
5.文字的绘制

效果图：进度条颜色由浅到深

一共就几个方法：测量-绘制

 · onMeasure

 · onDraw

再暴露出去设置进度和总进度的两个方法就可以了

package com.example.yugusuperdemo;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;

/**
 * 圆形进度条控件
 * yugu 2022 8/27
 */
public class CircleProgress extends View {

    private static final String TAG = "MyProgress";


    private Paint _paint;
    private RectF _rectF;
    private Rect _rect;
    private int _current = 20, _max = 100;
    //圆弧（也可以说是圆环）的宽度
    private float _arcWidth = 35;
    //控件的宽度
    private float _width;
    private int alpha = 0;

    public CircleProgress(Context context) {
        this(context, null);
    }

    public CircleProgress(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public CircleProgress(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        _paint = new Paint();
        _paint.setAntiAlias(true);
        _rectF = new RectF();
        _rect = new Rect();
    }

    public void SetCurrent(int _current) {
        Log.i(TAG, "当前值：" + _current + "，最大值：" + _max);
        this._current = _current;
        invalidate();
    }

    public void SetMax(int _max) {
        this._max = _max;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        //getMeasuredWidth获取的是view的原始大小，也就是xml中配置或者代码中设置的大小
        //getWidth获取的是view最终显示的大小，这个大小不一定等于原始大小
        _width = getMeasuredWidth();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //绘制圆形
        //设置为空心圆，如果不理解绘制弧线是什么意思就把这里的属性改为“填充”，跑一下瞬间就明白了
        _paint.setStyle(Paint.Style.STROKE);
        //设置圆弧的宽度（圆环的宽度）
        _paint.setStrokeWidth(_arcWidth);
        _paint.setColor(Color.rgb(222, 235, 243));
        _paint.setStrokeCap(Paint.Cap.ROUND);
//        _paint.setShader(linearGradient);
//        _paint.setShadowLayer(10, 10, 10, Color.GRAY);

        //大圆的半径
        float bigCircleRadius = _width / 2;
        //小圆的半径
        float smallCircleRadius = bigCircleRadius - _arcWidth;
        //绘制小圆
        canvas.drawCircle(bigCircleRadius, bigCircleRadius, smallCircleRadius, _paint);
        _paint.setColor(Color.rgb(43, 114, 196));
        _paint.setAlpha((int) (alpha + ((float) _current / _max) * 280));
        _rectF.set(_arcWidth, _arcWidth, _width - _arcWidth, _width - _arcWidth);
        //绘制圆弧
        canvas.drawArc(_rectF, 270, _current * 360 / _max, false, _paint);

        //计算百分比
        String txt = _current * 100 / _max + "%";
        _paint.setStrokeWidth(9);
        _paint.setTextSize(95);
        _paint.getTextBounds(txt, 0, txt.length(), _rect);
        _paint.setColor(Color.rgb(108, 146, 201));
        //绘制百分比
        canvas.drawText(txt, bigCircleRadius - _rect.width() / 2, bigCircleRadius + _rect.height() / 2, _paint);
    }

}

补充：_paint.setShadowLayer(10, 10, 10, Color.GRAY);设置阴影效果_paint.setColor(Color.rgb(222, 235, 243));rgb随意更换
linearGradient可以设置渐变  

attrs文件

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="CircleProgressbar">
        <attr name="radius" format="dimension"/>
        <attr name="strokeWidth" format="dimension"/>
        <attr name="ringColor" format="color"/>
        <attr name="textColor" format="color"/>
    </declare-styleable>
</resources>

调用 

<com.example.yugusuperdemo.CircleProgress
            android:id="@+id/ps"
            android:layout_width="@dimen/dp_200"
            android:layout_height="@dimen/dp_200"/>

public class ScanFragment extends Fragment {
    private boolean _threadFlag = false;
    private CircleProgress myCircleProgress;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_scan, container, false);
        initView(view);
        return view;
    }

    private void initView(View view) {
        //设置总加载大小为总缓存数量，每秒刷新当前缓存的清理进度去刷新进度条
        myCircleProgress = view.findViewById(R.id.ps);
        myCircleProgress.SetMax(100);
        new Thread(runnable).start();

    }
    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            try {

            } catch (Exception exception) {

            }
            int j = 0;
            while (!_threadFlag && j < 100) {
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                j++;
                int finalJ = j;
                requireActivity().runOnUiThread(() -> myCircleProgress.SetCurrent(finalJ));
            }
        }
    };
}

比我做的好的大佬很多，这个可以参考：Android自定义View之画圆环(进阶篇:圆形进度条)_游走的大千世界的烤腰子的博客-CSDN博客_android圆弧进度条