心电图效果View Android自定义View

 转载：http://blog.csdn.net/wingichoy/article/details/51023865
 
拿到图，先做一些简单的分析。呃..

• 背景表格的绘制
• 心电图的绘制

背景表格的绘制：

首先drawColor黑色，然后用循环来画线、

心电图的绘制：

看样子是path，应该没问题。

于是就大干一番，按照这俩步骤画完了。。结果发现，嗯。。确实画上去了，关键怎么让他动呢。。 轻而易举想到scrollBy吧。然后你就发现。。背景也跟着变了。。 遇到问题就要解决。。所以这里投机取巧一下 把两个View分离，即背景是一个View，折线图是一个View。

首先，创建一个View，用来做背景View。他有一些属性，因为这些View本来是一个，后来又有一个折现View需要相同的属性，所以索性偷懒改成protected修饰。。 

<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);">CardiographView</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-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//画笔</span>    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> Paint mPaint;    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//折现的颜色</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;">int</span> mLineColor = Color.parseColor(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"#76f112"</span>);    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//网格颜色</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;">int</span> mGridColor = Color.parseColor(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"#1b4200"</span>);    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//小网格颜色</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;">int</span> mSGridColor = Color.parseColor(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"#092100"</span>);    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//背景颜色</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;">int</span> mBackgroundColor = Color.BLACK;    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//自身的大小</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;">int</span> mWidth,mHeight;    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//网格宽度</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;">int</span> mGridWidth = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">50</span>;    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//小网格的宽度</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;">int</span> mSGridWidth = <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;">//心电图折现</span>    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> Path mPath ;</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>

定义了这些属性，在构造器里初始化一下画笔和Path

<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-title" style="box-sizing: border-box;">CardiographView</span>(Context context) {        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>(context,<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>);    }    <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;">CardiographView</span>(Context context, AttributeSet attrs) {        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>(context, attrs,<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;">public</span> <span class="hljs-title" style="box-sizing: border-box;">CardiographView</span>(Context context, AttributeSet attrs, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> defStyleAttr) {        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>(context, attrs, defStyleAttr);        mPaint = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Paint();        mPath = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Path();    }</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></ul>

接下来拿到自身的宽高。注意为了简化例子，这里就不测量了

<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;">onSizeChanged</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> w, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> h, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> oldw, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> oldh) {        mWidth = w;        mHeight = h;        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onSizeChanged(w, h, oldw, oldh);    }</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></ul>

准备工作都完成，开始绘制背景，创建一个drawBackground(Canvas canvas)方法。 
可以想到，用for循环来画横线竖线。横线的起始x坐标都是0，终止x坐标是mWidth， y坐标为i*mGridWidth（网格宽度），我们要拿到网格的个数，即宽高除以网格宽度，具体操作看代码：

<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;"> private void initBackground(Canvas <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;">canvas</span>.drawColor(mBackgroundColor);        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//画小网格</span>        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//竖线个数</span>        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> vSNum = mWidth /mSGridWidth;        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//横线个数</span>        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> hSNum = mHeight/mSGridWidth;        mPaint.setColor(mSGridColor);        mPaint.setStrokeWidth(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>);        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//画竖线</span>        <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<vSNum+<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;i++){            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">canvas</span>.drawLine(i<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">*mSGridWidth</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>,i<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">*mSGridWidth</span>,mHeight,mPaint);        }        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//画横线</span>        <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<hSNum+<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;i++){            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">canvas</span>.drawLine(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>,i<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">*mSGridWidth</span>,mWidth,i<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">*mSGridWidth</span>,mPaint);        }        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//竖线个数</span>        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> vNum = mWidth / mGridWidth;        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//横线个数</span>        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> hNum = mHeight / mGridWidth;        mPaint.setColor(mGridColor);        mPaint.setStrokeWidth(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>);        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//画竖线</span>        <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<vNum+<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;i++){            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">canvas</span>.drawLine(i<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">*mGridWidth</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>,i<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">*mGridWidth</span>,mHeight,mPaint);        }        <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//画横线</span>        <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<hNum+<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;i++){            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">canvas</span>.drawLine(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>,i<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">*mGridWidth</span>,mWidth,i<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">*mGridWidth</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><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></ul>

现在的运行效果是这样的：