Android - 打造3D自定义view

感谢CSDN博主：旋转跳跃就团灭的wing~，转载一下，膜拜一下~

原文地址：http://blog.csdn.net/wingichoy/article/details/50590051

分享一则最近流行的笑话： 

最新科学研究表明:寒冷可以使人保持年轻,楼下的王大爷表示虽然今年已经60多岁了，但是仍然冷的跟孙子一样。

呃。好吧，这个冬天确实有点冷，在广州活生生的把我这个原生北方人，冻成一条狗。（研究表明：寒冷可以让人类基因突变。。。。）

好了不扯了。前些日子有朋友让我写博客来分析一下这个仿MIUI的时钟，从中学到了一些炫酷效果的实现。 
https://github.com/AvatarQing/MiClockView 感谢原作者的开源精神！

那么是啥3D效果呢，先来看看效果图，额。。有好多个：

 
 
 
其实后两个都是png来的。。

转载请注明出处：http://blog.csdn.net/wingichoy/article/details/50590051

那么请问，看到图形的变换，你想到了什么？ 
没错！就是Matrix。 
关于Matrix你可以到爱哥的博客了解到及其详细的讲解（谢谢爱哥！）。

下面我们就来研究一下如何用矩阵，实现这个3d的效果。

首先新建自定义view类。

<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">TDView</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">View</span> {</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> Paint mPaint;

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> mCenterX;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> mCenterY;
     <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-title" style="box-sizing: border-box;">TDView</span>(Context context, AttributeSet attrs) {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>(context, attrs);
        mPaint = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Paint();
    }
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>

然后在圆心画一个圆出来

<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"> <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onDraw</span>(Canvas canvas) {

        mCenterX = getWidth() / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>;
        mCenterY = getHeight() / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>;
        canvas.drawCircle(mCenterX,mCenterY,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">100</span>,mPaint);
    }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul>

现在是这样的： 

我们知道，处理一个图片的时候（切错）可以使用矩阵来处理，同时处理X，Y的话可以使用Camera类，camera可以生成一个指定效果的矩阵。直接来看用法：

<code class="hljs cs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> Camera mCamera;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> Matrix mMatrix；

mMatrix = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Matrix();
mCamera = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Camera();</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>

在onDraw里 把camera给旋转一下，并把生成的矩阵给一个矩阵。再把矩阵应用到canvas，看一下效果。

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">        mMatrix<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.reset</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mCamera<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.save</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mCamera<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.rotateX</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mCamera<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.rotateY</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">20</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mCamera<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getMatrix</span>(mMatrix)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mCamera<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.restore</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        //将矩阵作用于整个canvas
        canvas<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.concat</span>(mMatrix)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul>

 
呃。。。确实是变形了。。但是好像不是我们想要的结果？ 
这是因为，矩阵的变换坐标总从左上角(0,0)开始。所以我们要把变换的坐标改为中心点，方法如下：

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">        mMatrix<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.reset</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mCamera<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.save</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mCamera<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.rotateX</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mCamera<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.rotateY</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">20</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mCamera<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getMatrix</span>(mMatrix)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mCamera<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.restore</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        //改变矩阵作用点
        mMatrix<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.preTranslate</span>(-mCenterX, -mCenterY)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mMatrix<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.postTranslate</span>(mCenterX, mCenterY)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        canvas<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.concat</span>(mMatrix)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>

此时的效果看起来像是向左倾斜了： 

接下来让他跟随手指移动,重写onTouchEvent：

<code class="hljs cs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"> @Override
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> boolean <span class="hljs-title" style="box-sizing: border-box;">onTouchEvent</span>(MotionEvent <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">event</span>) {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> x = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">event</span>.getX();
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> y = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">event</span>.getY();

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> action = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">event</span>.getActionMasked();
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">switch</span> (action) {
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> MotionEvent.ACTION_MOVE: {
                <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//这里将camera旋转的变量赋值</span>
                mCanvasRotateY = y;
                mCanvasRotateX = x;
                invalidate();
                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
            }
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> MotionEvent.ACTION_UP: {

                <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//这里将camera旋转的变量赋值</span>
                mCanvasRotateY = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;
                mCanvasRotateX = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;
                invalidate();

                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
            }
        }
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> super.onTouchEvent(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">event</span>);
    }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li></ul>

哈哈。。看看是什么效果： 

什么鬼，怎么跟转硬币一样。 因为旋转的X,Y给的太大了呗。所以要约束一下。

定义一个旋转最大值 
private float mCanvasMaxRotateDegree = 20; 
再用percent思想（前面博客有提到），来处理手指触摸点和这个度数变化的关系：

<code class="hljs cpp has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> rotateCanvasWhenMove(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> x, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> y) {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> dx = x - mCenterX;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> dy = y - mCenterY;

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> percentX = dx / mCenterX;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> percentY = dy /mCenterY;

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (percentX > <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1f</span>) {
            percentX = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1f</span>;
        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (percentX < -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1f</span>) {
            percentX = -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1f</span>;
        }
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (percentY > <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1f</span>) {
            percentY = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1f</span>;
        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (percentY < -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1f</span>) {
            percentY = -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1f</span>;
        }

        mCanvasRotateY = mCanvasMaxRotateDegree * percentX;
        mCanvasRotateX = -(mCanvasMaxRotateDegree * percentY);

    }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li></ul>

最后将TouchEvent里面的ACTION_MOVE 调用此函数即可。 
此时，完整的代码如下：

<code class="hljs java has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> mCenterX;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> mCenterY;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> mCanvasRotateX = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> mCanvasRotateY = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> mCanvasMaxRotateDegree = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">20</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> Matrix mMatrix = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Matrix();
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> Camera mCamera = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Camera();
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> Paint mPaint;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-title" style="box-sizing: border-box;">TDView</span>(Context context) {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>(context);
    }
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-title" style="box-sizing: border-box;">TDView</span>(Context context, AttributeSet attrs) {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>(context, attrs);
        mPaint = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Paint();
        mCanvasMaxRotateDegree = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">20</span>;
    }



    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onDraw</span>(Canvas canvas) {

        mCenterX = getWidth() / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>;
        mCenterY = getHeight() / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>;
        rotateCanvas(canvas);
        canvas.drawCircle(mCenterX, mCenterY, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">100</span>, mPaint);



    }

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">rotateCanvas</span>(Canvas canvas) {
        mMatrix.reset();
        mCamera.save();
        mCamera.rotateX(mCanvasRotateX);
        mCamera.rotateY(mCanvasRotateY);
        mCamera.getMatrix(mMatrix);
        mCamera.restore();
        mMatrix.preTranslate(-mCenterX, -mCenterY);
        mMatrix.postTranslate(mCenterX, mCenterY);

        canvas.concat(mMatrix);
    }

    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="box-sizing: border-box;">onTouchEvent</span>(MotionEvent event) {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> x = event.getX();
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> y = event.getY();

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> action = event.getActionMasked();
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">switch</span> (action) {
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> MotionEvent.ACTION_DOWN: {
                rotateCanvasWhenMove(x, y);
                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
            }
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> MotionEvent.ACTION_MOVE: {
                rotateCanvasWhenMove(x, y);
                invalidate();
                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
            }
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> MotionEvent.ACTION_UP: {
                mCanvasRotateY = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;
                mCanvasRotateX = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;
                invalidate();

                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
            }
        }
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onTouchEvent(event);
    }

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">rotateCanvasWhenMove</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> x, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> y) {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> dx = x - mCenterX;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> dy = y - mCenterY;

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> percentX = dx / mCenterX;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> percentY = dy /mCenterY;

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (percentX > <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>f) {
            percentX = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>f;
        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (percentX < -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>f) {
            percentX = -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>f;
        }
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (percentY > <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>f) {
            percentY = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>f;
        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (percentY < -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>f) {
            percentY = -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>f;
        }

        mCanvasRotateY = mCanvasMaxRotateDegree * percentX;
        mCanvasRotateX = -(mCanvasMaxRotateDegree * percentY);
    }


}
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li><li style="box-sizing: border-box; padding: 0px 5px;">64</li><li style="box-sizing: border-box; padding: 0px 5px;">65</li><li style="box-sizing: border-box; padding: 0px 5px;">66</li><li style="box-sizing: border-box; padding: 0px 5px;">67</li><li style="box-sizing: border-box; padding: 0px 5px;">68</li><li style="box-sizing: border-box; padding: 0px 5px;">69</li><li style="box-sizing: border-box; padding: 0px 5px;">70</li><li style="box-sizing: border-box; padding: 0px 5px;">71</li><li style="box-sizing: border-box; padding: 0px 5px;">72</li><li style="box-sizing: border-box; padding: 0px 5px;">73</li><li style="box-sizing: border-box; padding: 0px 5px;">74</li><li style="box-sizing: border-box; padding: 0px 5px;">75</li><li style="box-sizing: border-box; padding: 0px 5px;">76</li><li style="box-sizing: border-box; padding: 0px 5px;">77</li><li style="box-sizing: border-box; padding: 0px 5px;">78</li><li style="box-sizing: border-box; padding: 0px 5px;">79</li><li style="box-sizing: border-box; padding: 0px 5px;">80</li><li style="box-sizing: border-box; padding: 0px 5px;">81</li><li style="box-sizing: border-box; padding: 0px 5px;">82</li><li style="box-sizing: border-box; padding: 0px 5px;">83</li><li style="box-sizing: border-box; padding: 0px 5px;">84</li><li style="box-sizing: border-box; padding: 0px 5px;">85</li><li style="box-sizing: border-box; padding: 0px 5px;">86</li><li style="box-sizing: border-box; padding: 0px 5px;">87</li><li style="box-sizing: border-box; padding: 0px 5px;">88</li><li style="box-sizing: border-box; padding: 0px 5px;">89</li><li style="box-sizing: border-box; padding: 0px 5px;">90</li><li style="box-sizing: border-box; padding: 0px 5px;">91</li><li style="box-sizing: border-box; padding: 0px 5px;">92</li><li style="box-sizing: border-box; padding: 0px 5px;">93</li><li style="box-sizing: border-box; padding: 0px 5px;">94</li><li style="box-sizing: border-box; padding: 0px 5px;">95</li><li style="box-sizing: border-box; padding: 0px 5px;">96</li></ul>

简简单单100行代码，实现了3D效果的view： 

接下来做什么呢？ 
当然是把这个效果加到我们的自定义view里面！ 
比如，把我的PanelView加上这个效果： 
 
哗！瞬间高大上！

那么，你要不要跟我趁热来一发自定义view？ 
说搞就搞！

在原有类上进行修改 
给一个好看的底色，画一条线

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">        mBgColor = Color<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.parseColor</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"#227BAE"</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        canvas<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.drawLine</span>(mCenterX,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">100</span>,mCenterX,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">130</span>,mPaint)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>

 
嗯。不错 有条线了。微调下间距，旋转画布，画出整个圆形来：

//保存坐标系 
canvas.save(); 
for (int i = 0; i < 120; i++) { 
canvas.rotate(3,mCenterX,mCenterY); 
canvas.drawLine(mCenterX, 150, mCenterX, 170, mPaint); 
} 
//恢复坐标系 
canvas.restore(); 
 
嗯。。看起来想点样子了。 接下来调整透明度。

<code class="hljs mel has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">canvas</span>.save();
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>; i < <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">120</span>; i++) {
            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//根据i调整透明度alpha</span>
            mPaint.setAlpha(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">255</span>-(mAlpha * i/<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">120</span>));
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">canvas</span>.drawLine(mCenterX, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">150</span>, mCenterX, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">170</span>, mPaint);

            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">canvas</span>.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">rotate</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>,mCenterX,mCenterY);
        }
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">canvas</span>.restore();</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>

 
哈哈。。有没有点意思呢。。 
我们画个圆球上去！画之前先ctrl + alt + m 把之前画弧的方法提出来。 
画一个紧挨着的圆

<code class="hljs cs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">
 <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">drawCircle</span>(Canvas canvas) {
        mPaint.setAlpha(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">255</span>);
        canvas.drawCircle(mCenterX,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">213</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>,mPaint);
    }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>

不错不错，给点动态效果吧，让圆点跟着我们触摸的地方走。怎么做呢。。 当然还是旋转画布了！ 
这里需要注意的是触摸点与12点钟方向形成的夹角计算。画图分析一下 

可以看到 我们只需要调用Math.atan方法即可算出a的弧度，再将其转换为角度即可，在进行3D旋转之前，旋转画布：

<code class="hljs cs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onDraw</span>(Canvas canvas) {
        canvas.drawColor(mBgColor);
        mCenterX = getWidth() / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>;
        mCenterY = getHeight() / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>;

        Log.e(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"wing"</span>,alpha+<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>);
        canvas.rotate((<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span>) alpha,mCenterX,mCenterY);

        alpha = Math.atan((mTouchX-mCenterX)/(mCenterY-mTouchY));
        alpha = Math.toDegrees(alpha);
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(mTouchY>mCenterY){
            alpha = alpha+<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">180</span>;</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>

现在看一下效果： 

效果出来了，但是还美中不足呀。 因为中间太空了，所以这个3D效果看起来有点奇怪。那就给他中间加点东西吧！ 比如一个指针。

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">   private void drawPath(Canvas canvas) {
        mPath<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.moveTo</span>(mCenterX,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">223</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mPath<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.lineTo</span>(mCenterX-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">30</span>,mCenterY)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mPath<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.lineTo</span>(mCenterX,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>*mCenterY-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">223</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mPath<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.lineTo</span>(mCenterX+<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">30</span>,mCenterY)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mPath<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.lineTo</span>(mCenterX,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">233</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mPath<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.close</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>

        canvas<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.drawPath</span>(mPath,mPaint)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        mPaint<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setColor</span>(Color<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.parseColor</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"#55227BAE"</span>))<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
        canvas<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.drawCircle</span>(mCenterX,mCenterY,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">20</span>,mPaint)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
    }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>

最后大功告成！！！ 看效果！