下载进度条

package com.app.progressview;

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

import androidx.annotation.Nullable;

public class ProgressView extends View {
    static String MAX = "100%";
    private Paint mPaint;
    private Rect mTextBound;
    private Rect mClipBound;

    private float mTextSize;    //dp
    private int mRadius;        //px
    private int mColor;
    private float mStrokeWidth; //dp

    private int mProgress;      // progress:[0, 100]
    private float offset;       //px
    private int mTextHeight;     //px


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

    public ProgressView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public ProgressView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(context, attrs);
    }

    void init(Context context, AttributeSet attrs) {
        float density = getResources().getDisplayMetrics().density;
        //get attrs
        TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.ProgressView);
        mTextSize = ta.getDimension(R.styleable.ProgressView_textSize, 16 * density);
        mRadius = ta.getDimensionPixelSize(R.styleable.ProgressView_radius, 0);
        mColor = ta.getColor(R.styleable.ProgressView_color, Color.BLUE);
        mStrokeWidth = ta.getDimension(R.styleable.ProgressView_strokeWidth, 2 * density);
        Log.e("TAG", mRadius + " " + mStrokeWidth);
        ta.recycle();
        //init paint
        mPaint = new Paint();
        mPaint.setDither(true);
        mPaint.setAntiAlias(true);
        mPaint.setTextSize(mTextSize);
        mPaint.setColor(Color.BLUE);
        float strokeWidth = mStrokeWidth;
        mPaint.setStrokeWidth(strokeWidth);
        offset = strokeWidth / 2;
        //text info
        mTextBound = new Rect();
        //progress
        mClipBound = new Rect();
        Paint.FontMetricsInt fontMetricsInt = mPaint.getFontMetricsInt();
        mTextHeight = fontMetricsInt.descent + fontMetricsInt.ascent;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);

        int width;
        int height;

        int measuredWidth = getMeasuredWidth();
        int measuredHeight = getMeasuredHeight();
        //dp,math_parent
        if (widthMode == MeasureSpec.EXACTLY) {
            width = widthSize;
        } else if (widthMode == MeasureSpec.AT_MOST) {  //warp_content
            mPaint.getTextBounds(MAX, 0, MAX.length(), mTextBound);
            width = mTextBound.width();
        } else {
            width = 0;
        }

        if (heightMode == MeasureSpec.EXACTLY) {
            height = heightSize;
        } else if (heightMode == MeasureSpec.AT_MOST) {
            Paint.FontMetricsInt fontMetricsInt = mPaint.getFontMetricsInt();
            int ascent = fontMetricsInt.ascent;
            int descent = fontMetricsInt.descent;
            int textHeight = descent - ascent;
            height = textHeight;
        } else {
            height = 0;
        }
        setMeasuredDimension(width, height);
    }

    String mText = "0%";

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        int width = getMeasuredWidth();
        int height = getMeasuredHeight();
        int startX;
        int startY;
        mText = mProgress + "%";
        int progress = (int) (width * mProgress / 100.0f);
        //确定分割点
        mClipBound.left = 0;
        mClipBound.top = 0;
        mClipBound.right = progress;
        mClipBound.bottom = height;

        //把文本绘制到中间位置
        //获取文本信息，确定起点x坐标
        mPaint.getTextBounds(mText, 0, mText.length(), mTextBound);
        startX = (width - mTextBound.width()) / 2;

        //获取文本信息，确定起点y坐标
        startY = (height - mTextHeight) / 2;

        mPaint.setStyle(Paint.Style.FILL);

        //draw left part
        canvas.save();
        canvas.clipRect(mClipBound);
        mPaint.setColor(mColor);
        canvas.drawRoundRect(0, 0, width, height, mRadius, mRadius, mPaint);
        mPaint.setColor(Color.WHITE);
        canvas.drawText(mText, startX, startY, mPaint);
        canvas.restore();

        mClipBound.left = progress;
        mClipBound.top = 0;
        mClipBound.right = width;
        mClipBound.bottom = height;

        //draw right part
        canvas.save();
        canvas.clipRect(mClipBound);
        mPaint.setColor(Color.WHITE);
        canvas.drawRoundRect(0, 0, width, height, mRadius, mRadius, mPaint);
        mPaint.setColor(mColor);
        canvas.drawText(mText, startX, startY, mPaint);
        canvas.restore();

        //draw outline
        mPaint.setStyle(Paint.Style.STROKE);
        canvas.drawRoundRect(0 + offset, 0 + offset, width - offset, height - offset, mRadius, mRadius, mPaint);

    }

    //progress:[0,100]
    public void setmProgress(int mProgress) {
        if (mProgress >= 0 && mProgress <= 100) {
            this.mProgress = mProgress;
            invalidate();
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="ProgressView">
        <attr name="textSize" format="reference|dimension" />
        <attr name="color" format="reference|color" />
        <attr name="radius" format="reference|dimension" />
        <attr name="strokeWidth" format="reference|dimension" />
    </declare-styleable>
</resources>

package com.app.progressview;

import android.os.Bundle;
import android.view.View;

import androidx.appcompat.app.AppCompatActivity;

import java.util.Timer;
import java.util.TimerTask;

public class MainActivity extends AppCompatActivity {

    private ProgressView mProgressView;
    int progress = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mProgressView = findViewById(R.id.progressView);
        findViewById(R.id.start).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                onStartClick();
            }
        });

    }

    private void onStartClick() {
        final Timer timer = new Timer();
        TimerTask task = new TimerTask() {
            @Override
            public void run() {
                if (progress >= 100) {
                    timer.cancel();
                    return;
                }
                progress++;
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        mProgressView.setmProgress(progress);
                    }
                });
            }
        };
        timer.schedule(task, 0, 60);
    }
}