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Android进度条

吐尔洪江Coding 人气:0

前言

之前用华为Android系统的时候总是会想到这种虚线进度条是怎么实现的，因为直接用canvas的drawArc方法画出来的是实线，所以最近在网上搜了很多进度条相关的文章，也了解到了其中的原理，下面分享给大家。下面这两篇文章是我之前写的Android进度条相关的文章，有兴趣的朋友们可以看看：

Android实现绚丽的自定义进度条

详解Android如何自定义view实现圆形进度条

下面开始讲解虚线进度条的实现方法，首先看一张图：

实现步骤

大家可以先想想这种进度条是怎么实现的？网上有各种各样的方法，也有人用path的lineTo()方法实现了类似的效果。但是我个人觉得canvas的drawArc方法也是个不错的选择，适合自己的才是最好的。

canvas.drawArc(rectF, 0, process, false, mPaint);

阅读了大量文章，最后发现改变paint的样式是最简单好用的方法。给paint设置一个effect就好了。

1.用DashPathEffect给paint加上虚线效果

DashPathEffect dashPathEffect = new DashPathEffect(new float[]{8, 6}, 0);
mPaintBack.setPathEffect(dashPathEffect);

build一下项目，看到的结果是这样的：

能实现这个效果就大功告成了，如果看过我前面两篇文章的朋友们就知道，后面的步骤就简单了，加个进度条和动画效果就可以了。

private void drawBack(Canvas canvas) {
        RectF rectF = new RectF(strokeWidth, strokeWidth, getWidth() - strokeWidth, getHeight() - strokeWidth);
        PathEffect effects = new DashPathEffect(new float[]{8, 6}, 0);
        mPaintBack.setPathEffect(effects);
        canvas.drawArc(rectF, 0, 360, false, mPaintBack);
    }

2.画出进度条 

画进度条和画背景完全一样，只是画笔颜色和小点个数不一样。

代码如下：

 private void drawProgress(Canvas canvas) {
        RectF rectF = new RectF(strokeWidth, strokeWidth, getWidth() - strokeWidth, getHeight() - strokeWidth);
        PathEffect effects = new DashPathEffect(new float[]{8, 6}, 0);
        mPaint.setPathEffect(effects);
        canvas.drawArc(rectF, 0, process, false, mPaint);
    }

3.绘制文字 

接下来是绘制文字，实现文字居中的效果。思路是计算出圆心，调用canvas.drawText的方法就能在canvas上面绘制文字了。这里不需要更新进度文字，所以就更省事了。

EMUI 下面的10.0.0也是一样的方法，只是给Y坐标加一下55，往下移一点就好。

    //绘制文字
    private void drawText(Canvas canvas) {
        int mTxtWidth = getTextWidth();
        int mTxtHeight = getTextHeight();
        int x = getWidth() / 2 - mTxtWidth / 2;
        int y = getHeight() / 2 + mTxtHeight / 4;
        canvas.drawText(getResources().getString(R.string.defaultTextEmui), x, y, mPaintText);
    }
 
    //绘制下方文字
    private void drawTextBlow(Canvas canvas) {
        int mTxtWidth = getTextWidthBlow();
        int mTxtHeight = getTextHeight();
        int x = getWidth() / 2 - mTxtWidth / 2;
        int y = getHeight() / 2 + mTxtHeight / 4 + 55;
        canvas.drawText(getResources().getString(R.string.defaultTextBelow), x, y, mPaintTextLevel);
    }

4.加入动画效果

  /**
     * 设置动画效果
     */
    public void start() {
        ValueAnimator valueAnimator = ValueAnimator.ofInt(0, 360);
        valueAnimator.setDuration(duration);
        valueAnimator.setInterpolator(new LinearInterpolator());
        valueAnimator.addUpdateListener(animation -> {
            process = (int) animation.getAnimatedValue();
            invalidate();
        });
        valueAnimator.start();
    }

最终效果：

完整代码

package com.example.floatingwindow.widget;
 
import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.DashPathEffect;
import android.graphics.Paint;
import android.graphics.PathEffect;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.View;
import android.view.animation.LinearInterpolator;
 
import androidx.annotation.Nullable;
 
import com.example.floatingwindow.R;
 
public class DottedLineProgressBar extends View {
 
    private Paint mPaint;
    private Paint mPaintBack;
    private Paint mPaintText;
    private Paint mPaintTextLevel;
    private int strokeWidth = 30;
    private int textSize = 22;
    private int textSizeBlow = 15;
    private long duration = 3500;
    private int process;
 
    public DottedLineProgressBar(Context context) {
        super(context);
        init();
    }
 
    public DottedLineProgressBar(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        init();
    }
 
    public DottedLineProgressBar(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }
 
    public void setStrokeWidth(int width) {
        strokeWidth = width;
    }
 
    public void setTextSize(int textSize) {
        this.textSize = textSize;
    }
 
    public void setDuration(long duration) {
        this.duration = duration;
    }
 
    public void setTextSizeBlow(int textSizeBlow) {
        this.textSizeBlow = textSizeBlow;
    }
 
    //初始化画笔
    private void init() {
        mPaintBack = new Paint();//圆角矩形
        mPaintBack.setColor(getResources().getColor(R.color.gray));//圆角矩形颜色
        mPaintBack.setAntiAlias(true);// 抗锯齿效果
        mPaintBack.setStyle(Paint.Style.STROKE);//设置画笔样式
        mPaintBack.setStrokeWidth(strokeWidth);//设置画笔宽度
 
        mPaint = new Paint();
        mPaint.setColor(getResources().getColor(R.color.blue));
        mPaint.setAntiAlias(true);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(strokeWidth);
 
        mPaintText = new Paint();
        mPaintText.setAntiAlias(true);
        mPaintText.setStyle(Paint.Style.FILL);
        mPaintText.setColor(getResources().getColor(R.color.blue));
        mPaintText.setTextSize(sp2px(textSize));
 
        mPaintTextLevel = new Paint();
        mPaintTextLevel.setAntiAlias(true);
        mPaintTextLevel.setStyle(Paint.Style.FILL);
        mPaintTextLevel.setColor(getResources().getColor(R.color.gray));
        mPaintTextLevel.setTextSize(sp2px(textSizeBlow));
    }
 
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        drawBack(canvas);
        drawProgress(canvas);
        drawText(canvas);
        drawTextBlow(canvas);
    }
 
    private void drawBack(Canvas canvas) {
        RectF rectF = new RectF(strokeWidth, strokeWidth, getWidth() - strokeWidth, getHeight() - strokeWidth);
        PathEffect effects = new DashPathEffect(new float[]{8, 6}, 0);
        mPaintBack.setPathEffect(effects);
        canvas.drawArc(rectF, 0, 360, false, mPaintBack);
    }
 
    private void drawProgress(Canvas canvas) {
        RectF rectF = new RectF(strokeWidth, strokeWidth, getWidth() - strokeWidth, getHeight() - strokeWidth);
        PathEffect effects = new DashPathEffect(new float[]{8, 6}, 0);
        mPaint.setPathEffect(effects);
        canvas.drawArc(rectF, 0, process, false, mPaint);
    }
 
    //绘制文字
    private void drawText(Canvas canvas) {
        int mTxtWidth = getTextWidth();
        int mTxtHeight = getTextHeight();
        int x = getWidth() / 2 - mTxtWidth / 2;
        int y = getHeight() / 2 + mTxtHeight / 4;
        canvas.drawText(getResources().getString(R.string.defaultTextEmui), x, y, mPaintText);
    }
 
    //绘制下方文字
    private void drawTextBlow(Canvas canvas) {
        int mTxtWidth = getTextWidthBlow();
        int mTxtHeight = getTextHeight();
        int x = getWidth() / 2 - mTxtWidth / 2;
        int y = getHeight() / 2 + mTxtHeight / 4 + 55;
        canvas.drawText(getResources().getString(R.string.defaultTextBelow), x, y, mPaintTextLevel);
    }
 
    private int getTextWidth() {
        String text = getResources().getString(R.string.defaultTextEmui);
        return (int) mPaintText.measureText(text, 0, text.length());
    }
 
    private int getTextWidthBlow() {
        String text = getResources().getString(R.string.defaultTextBelow);
        return (int) mPaintTextLevel.measureText(text, 0, text.length());
    }
 
    private int getTextHeight() {
        Paint.FontMetrics fm = mPaintText.getFontMetrics();
        return (int) Math.ceil(fm.descent - fm.ascent);
    }
 
    private int sp2px(int sp) {
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, sp,
                getResources().getDisplayMetrics());
    }
 
    /**
     * 设置动画效果
     */
    public void start() {
        ValueAnimator valueAnimator = ValueAnimator.ofInt(0, 360);
        valueAnimator.setDuration(duration);
        valueAnimator.setInterpolator(new LinearInterpolator());
        valueAnimator.addUpdateListener(animation -> {
            process = (int) animation.getAnimatedValue();
            invalidate();
        });
        valueAnimator.start();
    }
}

kotlin调用：

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
 
        setContentView(R.layout.activity_main)
 
        dottedLineProgressBar.post {
            dottedLineProgressBar.start()
        }
    }
}

XML:

        <com.example.floatingwindow.widget.DottedLineProgressBar
            android:id="@+id/dottedLineProgressBar"
            android:layout_width="200dp"
            android:layout_height="200dp"
            android:layout_gravity="center">
        </com.example.floatingwindow.widget.DottedLineProgressBar>

 以上就是完整的实现过程了。

项目源码：https://gitee.com/tu_erhongjiang/android-progress-bar

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