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：
<ProgressBar
android:id="@+id/progressBar"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="5dip"
android:layout_toRightOf="@+id/progressBarV"
android:indeterminate="false"
android:padding="2dip"
android:progress="50" />
根据style="?android:attr/progressBarStyleHorizontal"，我们找到源码中的style.xml
<style name="Widget.ProgressBar.Horizontal">
<item name="android:indeterminateOnly">false</item>
<item name="android:progressDrawable">@android:drawable/progress_horizontal</item>
<item name="android:indeterminateDrawable">@android:drawable/progress_indeterminate_horizontal</item>
<item name="android:minHeight">20dip</item>
<item name="android:maxHeight">20dip</item>
</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：
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@android:id/background">
<shape>
<corners android:radius="5dip" />
<gradient
android:startColor="#ff9d9e9d"
android:centerColor="#ff5a5d5a"
android:centerY="0.75"
android:endColor="#ff747674"
android:angle="270"
/>
</shape>
</item>
<item android:id="@android:id/secondaryProgress">
<clip>
<shape>
<corners android:radius="5dip" />
<gradient
android:startColor="#80ffd300"
android:centerColor="#80ffb600"
android:centerY="0.75"
android:endColor="#a0ffcb00"
android:angle="270"
/>
</shape>
</clip>
</item>
<item android:id="@android:id/progress">
<clip>
<shape>
<corners android:radius="5dip" />
<gradient
android:startColor="#ffffd300"
android:centerColor="#ffffb600"
android:centerY="0.75"
android:endColor="#ffffcb00"
android:angle="270"
/>
</shape>
</clip>
</item>
</layer-list>
看到android:id="@android:id/progress"木有，看到android:id="@android:id/secondaryProgress"木有
把这个文件复制到自己工程下的drawable，就可以随心所欲的修改shape的属性，渐变，圆角等等
那么怎么放一个图片进去呢，ok，新建progress_horizontal1.xml：
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@android:id/progress" android:drawable="@drawable/progressbar" />
</layer-list>
在android:drawable中指定你处理好的图片
然后回到布局中：
<ProgressBar
android:id="@+id/progressBar1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/progressBar"
android:layout_margin="5dip"
android:layout_toRightOf="@+id/progressBarV"
android:background="@drawable/progress_bg"
android:indeterminate="false"
android:indeterminateOnly="false"
android:maxHeight="20dip"
android:minHeight="20dip"
android:padding="2dip"
android:progress="50"
android:progressDrawable="@drawable/progress_horizontal1" />
android:background="@drawable/progress_bg"指定背景
android:progressDrawable="@drawable/progress_horizontal1"前景使用上面的progress_horizontal1
ok，搞定
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
<item android:id="@android:id/progress">
<clip>
<shape>
<corners android:radius="5dip" />
<gradient
android:startColor="#ffffd300"
android:centerColor="#ffffb600"
android:centerY="0.75"
android:endColor="#ffffcb00"
android:angle="270"
/>
</shape>
</clip>
</item>
为什么shape外面要包一层clip呢，官方文档解释是clipdrawable是可以自我复制的，来看看定义
<?xml version="1.0" encoding="utf-8"?>
<clip
xmlns:android="http://schemas.android.com/apk/res/android"
android:drawable="@drawable/drawable_resource"
android:clipOrientation=["horizontal" | "vertical"]
android:gravity=["top" | "bottom" | "left" | "right" | "center_vertical" |
"fill_vertical" | "center_horizontal" | "fill_horizontal" |
"center" | "fill" | "clip_vertical" | "clip_horizontal"] />
android:clipOrientation有两个属性，默认为horizontal
android:gravity有两个属性，默认为left
那我们试试改成vertical和bottom会有什么效果，新建一个progress_vertical.xml，把源码progress_horizontal.xml的内容复制过来，这里去掉了secondaryProgress，修改了clip，shape的渐变中心centerY改为centerX
<item android:id="@android:id/progress">
<clip
android:clipOrientation="vertical"
android:gravity = "bottom">
<shape>
<corners android:radius="5dip" />
<gradient
android:startColor="#ffffd300"
android:centerColor="#ffffb600"
android:centerX="0.75"
android:endColor="#ffffcb00"
android:angle="90"
/>
</shape>
</clip>
</item>
布局中android:progressDrawable="@drawable/progress_vertical"
ok，搞定，就是这么简单：
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：
public class Arcs extends View {
private Paint mArcPaint;
private Paint mArcBGPaint;
private RectF mOval;
private float mSweep = 0;
private int mSpeedMax = 200;
private int mThreshold = 100;
private int mIncSpeedValue = 0;
private int mCurrentSpeedValue = 0;
private float mCenterX;
private float mCenterY;
private float mSpeedArcWidth;
private final float SPEED_VALUE_INC = 2;
..........
}
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。
mArcPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mArcPaint.setStyle(Paint.Style.STROKE);
mArcPaint.setStrokeWidth(mSpeedArcWidth);
// mPaint.setStrokeCap(Paint.Cap.ROUND);
mArcPaint.setColor(0xff81ccd6);
BlurMaskFilter mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.INNER);
mArcPaint.setMaskFilter(mBlur);
mArcBGPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mArcBGPaint.setStyle(Paint.Style.STROKE);
mArcBGPaint.setStrokeWidth(mSpeedArcWidth+8);
mArcBGPaint.setColor(0xff171717);
BlurMaskFilter mBGBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.INNER);
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。
@Override
protected void onSizeChanged(int w, int h, int ow, int oh) {
super.onSizeChanged(w, h, ow, oh);
Log.i("onSizeChanged w", w+"");
Log.i("onSizeChanged h", h+"");
mCenterX = w * 0.5f; // remember the center of the screen
mCenterY = h - mSpeedArcWidth;
mOval = new RectF(mCenterX - mCenterY, mSpeedArcWidth, mCenterX + mCenterY, mCenterY * 2);
}
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
@Override
protected void onDraw(Canvas canvas) {
drawSpeed(canvas);
calcSpeed();
}
private void drawSpeed(Canvas canvas) {
canvas.drawArc(mOval, 179, 181, false, mArcBGPaint);
mSweep = (float) mIncSpeedValue / mSpeedMax * 180;
if (mIncSpeedValue > mThreshold) {
mArcPaint.setColor(0xFFFF0000);
}
else {
mArcPaint.setColor(0xFF00B0F0);
}
canvas.drawArc(mOval, 180, mSweep, false, mArcPaint);
}
private void calcSpeed() {
if (mIncSpeedValue < mCurrentSpeedValue) {
mIncSpeedValue += SPEED_VALUE_INC;
if (mIncSpeedValue > mCurrentSpeedValue) {
mIncSpeedValue = mCurrentSpeedValue;
}
invalidate();
}
else if (mIncSpeedValue > mCurrentSpeedValue) {
mIncSpeedValue -= SPEED_VALUE_INC;
if (mIncSpeedValue < mCurrentSpeedValue) {
mIncSpeedValue = mCurrentSpeedValue;
}
invalidate();
}
}
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。
