Android如何实现动态滚动波形图(心电图)功能

  /** 根据网格的单位长宽，获取能绘制网格横线和竖线的数量*/
  gridHorizontalNum = (int) (mHeight / GRID_WIDTH);
  gridVerticalNum = (int) (mWidth / GRID_WIDTH);

 /**
  * 绘制网格
  *
  * @param canvas
  */
 private void drawGrid(Canvas canvas) {
  /** 设置颜色*/
  mLinePaint.setColor(gridLineColor);
  /** 绘制横线*/
  for (int i = 0; i < gridHorizontalNum + 1; i++) {
   canvas.drawLine(0, i * GRID_WIDTH,
     mWidth, i * GRID_WIDTH, mLinePaint);
  }
  /** 绘制竖线*/
  for (int i = 0; i < gridVerticalNum + 1; i++) {
   canvas.drawLine(i * GRID_WIDTH, 0,
     i * GRID_WIDTH, mHeight, mLinePaint);
  }
 }

  /** 根据线条长度，最多能绘制多少个数据点*/
  row = (int) (mWidth / WAVE_LINE_WIDTH);
  dataArray = new float[row + 10];

 /**
  * 添加新的数据
  */
 public void showLine(float line) {
  if (draw_index >= row) {
   draw_index = 0;
  }
  switch (drawMode){
   case 0:
    /** 常规模式数据添加至最后一位*/
    dataArray[row - 1] = line;
    break;
   case 1:
    /** 循环模式数据添加至当前绘制的位*/
    dataArray[draw_index] = line;
    break;
  }
  postInvalidate();
 }

 /**
  * 取数组中的指定一段数据来绘制折线
  * @param start 起始数据位
  * @param end 结束数据位
  * */
 private void drawPathFromDatas(Canvas canvas, int start, int end){
  mPath.reset();
  mPath.moveTo(start * WAVE_LINE_WIDTH, mHeight / 2);
  for (int i = start; i < end; i++) {
   nowX = i * WAVE_LINE_WIDTH;
   float dataValue = dataArray[i];
   /** 判断数据为正数还是负数 超过最大值的数据按最大值来绘制*/
   if (dataValue > 0) {
    if (dataValue > MAX_VALUE) {
     dataValue = MAX_VALUE;
    }
   } else {
    if (dataValue < -MAX_VALUE) {
     dataValue = -MAX_VALUE;
    }
   }
   nowY = mHeight / 2 - dataValue * (mHeight / (MAX_VALUE * 2));
   mPath.lineTo(nowX, nowY);
  }
  canvas.drawPath(mPath, mWavePaint);
 }

allprojects {
  repositories {
   ...
   maven { url 'https://jitpack.io' }
  }
 }

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 tools:context=".MainActivity">

 <TextView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="波形图1"
  android:textColor="#000000"
  android:textSize="24sp" />

 <com.giftedcat.wavelib.view.WaveView
  android:id="@+id/wave_view1"
  android:layout_width="match_parent"
  android:layout_height="1dp"
  android:layout_weight="1"
  app:draw_mode="loop"
  app:max_value="30"
  app:wave_background="#000000"
  app:wave_line_color="#ffff00"
  app:wave_line_width="20" />

 <TextView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="波形图2"
  android:textColor="#000000"
  android:textSize="24sp" />

 <com.giftedcat.wavelib.view.WaveView
  android:id="@+id/wave_view2"
  android:layout_width="match_parent"
  android:layout_height="1dp"
  android:layout_weight="1"
  app:draw_mode="normal"
  app:grid_visible="false"
  app:wave_line_stroke_width="5" />

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <declare-styleable name="WaveView">
  <!--最大值 默认为20，数据为-20 ~ 20-->
  <attr name="max_value" format="integer" />
  <!--波形图折线单位宽度，通过修改该参数，控制横坐标的单位-->
  <attr name="wave_line_width" format="integer" />
  <!--波形图折线的线宽-->
  <attr name="wave_line_stroke_width" format="integer" />
  <!--波形图折线的颜色-->
  <attr name="wave_line_color" format="string" />
  <!--背景网格图的颜色-->
  <attr name="grid_line_color" format="string" />
  <!--背景颜色，默认为黑-->
  <attr name="wave_background" format="string"/>
  <!--背景网格是否可见-->
  <attr name="grid_visible" format="boolean" />
  <!--波形图绘制模式，常规和循环-->
  <attr name="draw_mode" format="enum">
   <enum name="normal" value="0" />
   <enum name="loop" value="1" />
  </attr>
 </declare-styleable>
</resources>

    data = new Random().nextFloat()*(20f)-10f;
    waveShowView.showLine(data);//取得是-10到10间的浮点数