Android原生控件只有横向进度条一种，而且没法变换样式，比如原生rom的样子
很丑是吧，当伟大的产品设计要求更换前背景，甚至纵向，甚至圆弧状的，咋办，比如
ok，我们开始吧：
一）变换前背景
先来看看progressbar的属性：
1. <ProgressBar
2.
Android:id="@+id/progressBar"
3. style="?
Android:attr/progressBarStyleHorizontal"
4.
Android:layout_width="match_parent"
5.
Android:layout_height="wrap_content"
6.
Android:layout_margin="5dip"
7.
Android:layout_toRightOf="@+id/progressBarV"
8.
Android:indeterminate="false"
9.
Android:padding="2dip"
10.
Android:progress="50" />
根据style="?
Android:attr/progressBarStyleHorizontal"，我们找到源码中的style.xml
1. <style name="Widget.ProgressBar.Horizontal">
2. <item name="
Android:indeterminateOnly">false</item>
3. <item name="
Android:progressDrawable">@
Android:drawable/progress_horizontal</item>
4. <item name="
Android:indeterminateDrawable">@
Android:drawable/progress_indeterminate_horizontal</item>
5. <item name="
Android:minHeight">20dip</item>
6. <item name="
Android:maxHeight">20dip</item>
7. </style>
看到
<item name="
Android:progressDrawable">@
Android:drawable/progress_horizontal</item>
木有，继续发掘源码，找到drawable下面的progress_horizontal.xml，这就是我们今天的主角了：
1. <layer-list xmlns:
Android="http://schemas.
Android.com/apk/res/
Android">
2.
3. <item
Android:id="@
Android:id/background">
4. <shape>
5. <corners
Android:radius="5dip" />
6. <gradient
7.
Android[/img]
注意看，四角还是有圆倒角的，貌似是系统自己加上去的，总之我的图片里面是没有做这个倒角处理的
二）纵向进度条
还是得从源码入手，看回progress_horizontal.xml
1. <item
Android:id="@
Android:id/progress">
2. <clip>
3. <shape>
4. <corners
Android:radius="5dip" />
5. <gradient
6.
Android[/img]
三）弧形bar
这个也许算不上是进度条，用的也不多，最多也就仪表盘用用，不然谁会把进度条整成圆弧的呢。好吧这个可不是改改源码就能搞定的，看代码
1. public class Arcs extends View {
2. private Paint mArcPaint;
3. private Paint mArcBGPaint;
4.
5. private RectF mOval;
6. private float mSweep = 0;
7. private int mSpeedMax = 200;
8. private int mThreshold = 100;
9. private int mIncSpeedValue = 0;
10. private int mCurrentSpeedValue = 0;
11. private float mCenterX;
12. private float mCenterY;
13. private float mSpeedArcWidth;
14.
15. private final float SPEED_VALUE_INC = 2;
16.
17. ..........
18.
19. }
首先是一堆成员变量，两个Paint用来画圆弧一个前景一个背景，一个RectF圆弧就画在上面，然后是一些控制参数比如sweep圆弧扫过的角度，xy坐标等等
1. mArcPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
2. mArcPaint.setStyle(Paint.Style.STROKE);
3. mArcPaint.setStrokeWidth(mSpeedArcWidth);
4. // mPaint.setStrokeCap(Paint.Cap.ROUND);
5. mArcPaint.setColor(0xff81ccd6);
6. BlurMaskFilter mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.INNER);
7. mArcPaint.setMaskFilter(mBlur);
8.
9. mArcBGPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
10. mArcBGPaint.setStyle(Paint.Style.STROKE);
11. mArcBGPaint.setStrokeWidth(mSpeedArcWidth+8);
12. mArcBGPaint.setColor(0xff171717);
13.
14. BlurMaskFilter mBGBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.INNER);
15. mArcBGPaint.setMaskFilter(mBGBlur);
设置两个画笔，颜色，宽度，样式等等，BlurMaskFilter笔是边缘模糊效果，有几种，可以自己尝试
1. @Override
2. protected void onSizeChanged(int w, int h, int ow, int oh) {
3. super.onSizeChanged(w, h, ow, oh);
4. Log.i("onSizeChanged w", w+"");
5. Log.i("onSizeChanged h", h+"");
6. mCenterX = w * 0.5f; // remember the center of the screen
7. mCenterY = h - mSpeedArcWidth;
8. mOval = new RectF(mCenterX - mCenterY, mSpeedArcWidth, mCenterX + mCenterY, mCenterY * 2);
9. }
重写父类View的onSizeChanged，为的是自己根据布局中的大小做居中处理
1. @Override
2. protected void onDraw(Canvas canvas) {
3. drawSpeed(canvas);
4. calcSpeed();
5. }
6.
7. private void drawSpeed(Canvas canvas) {
8. canvas.drawArc(mOval, 179, 181, false, mArcBGPaint);
9.
10. mSweep = (float) mIncSpeedValue / mSpeedMax * 180;
11. if (mIncSpeedValue > mThreshold) {
12. mArcPaint.setColor(0xFFFF0000);
13. }
14. else {
15. mArcPaint.setColor(0xFF00B0F0);
16. }
17.
18. canvas.drawArc(mOval, 180, mSweep, false, mArcPaint);
19. }
20.
21. private void calcSpeed() {
22. if (mIncSpeedValue < mCurrentSpeedValue) {
23. mIncSpeedValue += SPEED_VALUE_INC;
24. if (mIncSpeedValue > mCurrentSpeedValue) {
25. mIncSpeedValue = mCurrentSpeedValue;
26. }
27. invalidate();
28. }
29. else if (mIncSpeedValue > mCurrentSpeedValue) {
30. mIncSpeedValue -= SPEED_VALUE_INC;
31. if (mIncSpeedValue < mCurrentSpeedValue) {
32. mIncSpeedValue = mCurrentSpeedValue;
33. }
34. invalidate();
35. }
36. }
重写onDraw以便重绘canvas
drawSpeed里面
通过计算mSweep = (float) mIncSpeedValue / mSpeedMax * 180;
然后canvas.drawArc(mOval, 180, mSweep, false, mArcPaint);
会根据mSweep的变化，画出相应长度的弧度来
根据与阈值的对比，还可以设定不同的 颜色：
if (mIncSpeedValue > mThreshold) {
mArcPaint.setColor(0xFFFF0000);
}
else {
mArcPaint.setColor(0xFF00B0F0);
}
calcSpeed通过一个步进来控制增量或减量，以使弧度自然过渡，减少跳跃
ok，大功告成
