android自定义seekBar

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