最近看到一些應(yīng)用在下載文件的時(shí)候，并沒有額外彈出進(jìn)度條，而是很炫的使用啟動(dòng)下載任務(wù)的Button直接顯示文件的下載進(jìn)度，通過改變其背景色，從左向右推進(jìn)，直到填滿整個(gè)Button時(shí)，意味著下載任務(wù)的完成。

除了這種效果，還看到某酷的視頻客戶端，在觀看過的視頻對(duì)應(yīng)的按鈕上，會(huì)給該按鈕添加一個(gè)描邊效果，4條邊，每條邊代表25%的進(jìn)度，由上沿開始，順時(shí)針最終到左邊沿，則代表100%的進(jìn)度，這種效果也很不錯(cuò)。

自己也研究了一下，寫了個(gè)自定義的button，下面是效果，

普通的填充效果：

描邊的效果：

自定義Button的主要實(shí)現(xiàn)就是繼承Button，并重寫onDraw()方法，填充的效果實(shí)現(xiàn)起來相對(duì)簡(jiǎn)單一點(diǎn)：

 if(currentType == TYPE_FILL) {
      mPaint.setColor(getContext().getResources().getColor(R.color.green_yellow));
      mPaint.setAntiAlias(true);
      mPaint.setAlpha(128);
      mPaint.setStrokeWidth(1.0f);
      Rect rect = new Rect();
      //先獲取Button的邊框
      canvas.getClipBounds(rect);
      rect.left += getPaddingLeft();
      //填充條的右邊界根據(jù)當(dāng)前進(jìn)度來計(jì)算
      rect.top += getPaddingTop();
      rect.right = (rect.left - getPaddingLeft()) + (mProgress * getWidth() / 100) - getPaddingRight();
      rect.bottom -= getPaddingBottom();
      //繪制一個(gè)圓角的長條，這樣相對(duì)好看一點(diǎn)
      canvas.drawRoundRect(new RectF(rect), 8.0f, 8.0f, mPaint);
    }

描邊效果實(shí)現(xiàn)起來相對(duì)復(fù)雜一點(diǎn)，確切說是繁瑣：

     else if(currentType == TYPE_STROKE) {
      //初始化畫筆
      mPaint.setAntiAlias(true);
      mPaint.setColor(getContext().getResources().getColor(R.color.green_yellow));
      mPaint.setAlpha(255);
      //獲取Button的邊框
      Rect rect = new Rect();
      canvas.getClipBounds(rect);
      Paint paint1, paint2, paint3, paint4;
      //根據(jù)當(dāng)前進(jìn)度，確定是繪制哪條邊，其實(shí)也是繪制一個(gè)矩形，只不過這個(gè)矩形比較扁或是比較窄而已，類似一條邊
      if(mProgress >= 0 && mProgress < 25) {
        paint1 = new Paint(mPaint);
        Rect temp = new Rect(rect.left + getPaddingLeft(),
            rect.top + getPaddingTop(),
            rect.left + mProgress * (getWidth() - getPaddingLeft() - getPaddingRight())
                / 25 - getPaddingRight(),
            rect.top + getPaddingTop() + 2);
        canvas.drawRect(temp, paint1);
      } else if(mProgress < 50) {
        paint1 = new Paint(mPaint);
        Rect rect1 = new Rect(rect.left + getPaddingLeft(),
            rect.top + getPaddingTop(), rect.right - getPaddingRight(),
            rect.top + getPaddingTop() + 2);
        canvas.drawRect(rect1, paint1);

        paint2 = new Paint(mPaint);
        Rect rect2 = new Rect(rect.right - getPaddingRight() - 2,
            rect.top + getPaddingTop(), rect.right - getPaddingRight(),
            rect.top + getPaddingTop() + (mProgress - 25) *
                (getHeight() - getPaddingTop() - getPaddingBottom()) / 25);
        canvas.drawRect(rect2, paint2);
      } else if(mProgress < 75) {
        paint1 = new Paint(mPaint);
        Rect rect1 = new Rect(rect.left + getPaddingLeft(),
            rect.top + getPaddingTop(), rect.right - getPaddingRight(),
            rect.top + getPaddingTop() + 2);
        canvas.drawRect(rect1, paint1);

        paint2 = new Paint(mPaint);
        Rect rect2 = new Rect(rect.right - getPaddingRight() - 2,
            rect.top + getPaddingTop(), rect.right - getPaddingRight(),
            rect.bottom - getPaddingBottom());
        canvas.drawRect(rect2, paint2);

        paint3 = new Paint(mPaint);
        Rect rect3 = new Rect(
            rect.right - getPaddingRight() - (mProgress - 50) *
                (getWidth() - getPaddingLeft() - getPaddingRight()) / 25,
            rect.bottom - getPaddingBottom() - 2,
            rect.right - getPaddingRight(),
            rect.bottom - getPaddingBottom());
        canvas.drawRect(rect3, paint3);
      } else if(mProgress <= 100) {
        paint1 = new Paint(mPaint);
        Rect rect1 = new Rect(
            rect.left + getPaddingLeft(),
            rect.top + getPaddingTop(), rect.right - getPaddingRight(),
            rect.top + getPaddingTop() + 2);
        canvas.drawRect(rect1, paint1);

        paint2 = new Paint(mPaint);
        Rect rect2 = new Rect(
            rect.right - getPaddingRight() - 2,
            rect.top + getPaddingTop(), rect.right - getPaddingRight(),
            rect.bottom - getPaddingBottom());
        canvas.drawRect(rect2, paint2);

        paint3 = new Paint(mPaint);
        Rect rect3 = new Rect(
            rect.left + getCompoundPaddingLeft(),
            rect.bottom - getPaddingBottom() - 2, rect.right - getPaddingRight(),
            rect.bottom - getPaddingRight());
        canvas.drawRect(rect3, paint3);

        paint4 = new Paint(mPaint);
        Rect rect4 = new Rect(
            rect.left + getCompoundPaddingLeft(),
            rect.bottom - getPaddingBottom() - (mProgress - 75) *
                (getHeight() - getPaddingTop() - getPaddingBottom()) / 25,
            rect.left + getPaddingLeft() + 2,
            rect.bottom - getPaddingBottom());
        canvas.drawRect(rect4, paint4);
      }
    }

記得最后執(zhí)行 super.onDraw(canvas);

這樣會(huì)讓填充或是描邊繪制在最底層，不會(huì)擋住Button原有的內(nèi)容。

然后添加一個(gè)API，用于更新進(jìn)度：

  public void updateProgress(int progress) {
    if(progress >= 0 && progress <= 100) {
      mProgress = progress;
      invalidate();
    } else if(progress < 0) {
      mProgress = 0;
      invalidate();
    } else if(progress > 100) {
      mProgress = 100;
      invalidate();
    }
  }

Demo的代碼上傳到了github上：https://github.com/YoungLeeForeverBoy/ProgressButton

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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