最近看到一些應用在下載文件的時候，并沒有額外彈出進度條，而是很炫的使用啟動下載任務的Button直接顯示文件的下載進度，通過改變其背景色，從左向右推進，直到填滿整個Button時，意味著下載任務的完成。
除了這種效果，還看到某酷的視頻客戶端，在觀看過的視頻對應的按鈕上，會給該按鈕添加一個描邊效果，4條邊，每條邊代表25%的進度，由上沿開始，順時針最終到左邊沿，則代表100%的進度，這種效果也很不錯。
自己也研究了一下，寫了個自定義的button，下面是效果，
普通的填充效果：
描邊的效果：
自定義Button的主要實現就是繼承Button，并重寫onDraw()方法，填充的效果實現起來相對簡單一點：
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當前進度來計算 rect.top += getPaddingTop(); rect.right = (rect.left - getPaddingLeft()) + (mProgress * getWidth() / 100) - getPaddingRight(); rect.bottom -= getPaddingBottom(); //繪制一個圓角的長條，這樣相對好看一點 canvas.drawRoundRect(new RectF(rect), 8.0f, 8.0f, mPaint); } 描邊效果實現起來相對復雜一點，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; //根據當前進度，確定是繪制哪條邊，其實也是繪制一個矩形，只不過這個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); } } 記得最后執行 super.onDraw(canvas);
這樣會讓填充或是描邊繪制在最底層，不會擋住Button原有的內容。
然后添加一個API，用于更新進度：
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內容，希望對大家的學習有所幫助，也希望大家多多支持武林網。
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