Android自定义可左右滑动和点击的折线图

前言

前几天有小盆友让我写一个折线图，可以点击，可以左右滑动。对于折线肯定有很多项目都使用过，所以网上肯定也有很多demo，像AndroidChart、HelloChart之类的，功能相当丰富，效果也很赞，但是太重了，其他的小demo又不符合要求，当然了，我写的自定义折线图的思想也有来自这些小demo，对他们表示感谢。

效果图

废话不多说，先上效果图：

效果是不是很赞，如果上图满足你的需求，那就继续往下看。

自定义折线图的步骤：

1、自定义view所需要的属性

确定所需要的自定义view的属性，然后在res/values目录下，新建一个attrs.xml文件，代码如下：

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <!-- xy坐标轴颜色 -->
 <attr name="xylinecolor" format="color" />
 <!-- xy坐标轴宽度 -->
 <attr name="xylinewidth" format="dimension" />
 <!-- xy坐标轴文字颜色 -->
 <attr name="xytextcolor" format="color" />
 <!-- xy坐标轴文字大小 -->
 <attr name="xytextsize" format="dimension" />
 <!-- 折线图中折线的颜色 -->
 <attr name="linecolor" format="color" />
 <!-- x轴各个坐标点水平间距 -->
 <attr name="interval" format="dimension" />
 <!-- 背景颜色 -->
 <attr name="bgcolor" format="color" />
 <!--是否在ACTION_UP时，根据速度进行自滑动，建议关闭，过于占用GPU-->
 <attr name="isScroll" format="boolean" />
 <declare-styleable name="chartView">
  <attr name="xylinecolor" />
  <attr name="xylinewidth" />
  <attr name="xytextcolor" />
  <attr name="xytextsize" />
  <attr name="linecolor" />
  <attr name="interval" />
  <attr name="bgcolor" />
  <attr name="isScroll" />
 </declare-styleable>
</resources>

2、在自定义view的构造方法中获取我们的自定义属性：

public ChartView(Context context) {
  this(context, null);
 }

 public ChartView(Context context, AttributeSet attrs) {
  this(context, attrs, 0);
 }

 public ChartView(Context context, AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);
  init(context, attrs, defStyleAttr);
  initPaint();
 }

 /**
  * 初始化
  *
  * @param context
  * @param attrs
  * @param defStyleAttr
  */
 private void init(Context context, AttributeSet attrs, int defStyleAttr) {
  TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.chartView, defStyleAttr, 0);
  int count = array.getIndexCount();
  for (int i = 0; i < count; i++) {
   int attr = array.getIndex(i);
   switch (attr) {
    case R.styleable.chartView_xylinecolor://xy坐标轴颜色
     xylinecolor = array.getColor(attr, xylinecolor);
     break;
    case R.styleable.chartView_xylinewidth://xy坐标轴宽度
     xylinewidth = (int) array.getDimension(attr, TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_PX, xylinewidth, getResources().getDisplayMetrics()));
     break;
    case R.styleable.chartView_xytextcolor://xy坐标轴文字颜色
     xytextcolor = array.getColor(attr, xytextcolor);
     break;
    case R.styleable.chartView_xytextsize://xy坐标轴文字大小
     xytextsize = (int) array.getDimension(attr, TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_PX, xytextsize, getResources().getDisplayMetrics()));
     break;
    case R.styleable.chartView_linecolor://折线图中折线的颜色
     linecolor = array.getColor(attr, linecolor);
     break;
    case R.styleable.chartView_interval://x轴各个坐标点水平间距
     interval = (int) array.getDimension(attr, TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_PX, interval, getResources().getDisplayMetrics()));
     break;
    case R.styleable.chartView_bgcolor: //背景颜色
     bgcolor = array.getColor(attr, bgcolor);
     break;
    case R.styleable.chartView_isScroll://是否在ACTION_UP时，根据速度进行自滑动
     isScroll = array.getBoolean(attr, isScroll);
     break;
   }
  }
  array.recycle();
 }
 /**
  * 初始化畫筆
  */
 private void initPaint() {
  xyPaint = new Paint();
  xyPaint.setAntiAlias(true);
  xyPaint.setStrokeWidth(xylinewidth);
  xyPaint.setStrokeCap(Paint.Cap.ROUND);
  xyPaint.setColor(xylinecolor);
  xyTextPaint = new Paint();
  xyTextPaint.setAntiAlias(true);
  xyTextPaint.setTextSize(xytextsize);
  xyTextPaint.setStrokeCap(Paint.Cap.ROUND);
  xyTextPaint.setColor(xytextcolor);
  xyTextPaint.setStyle(Paint.Style.STROKE);
  linePaint = new Paint();
  linePaint.setAntiAlias(true);
  linePaint.setStrokeWidth(xylinewidth);
  linePaint.setStrokeCap(Paint.Cap.ROUND);
  linePaint.setColor(linecolor);
  linePaint.setStyle(Paint.Style.STROKE);
 }

3、获取一写基本点

这些基本点包括：xy轴的原点坐标，第一个点的x轴的初始化坐标值以及其最大值和最小值。这些参数可以在onLayout（）方法里面获取。

 @Override
 protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
  if (changed) {
   //这里需要确定几个基本点，只有确定了xy轴原点坐标，第一个点的X坐标值及其最大最小值
   width = getWidth();
   height = getHeight();
   //Y轴文本最大宽度
   float textYWdith = getTextBounds("000", xyTextPaint).width();
   for (int i = 0; i < yValue.size(); i++) {//求取y轴文本最大的宽度
    float temp = getTextBounds(yValue.get(i) + "", xyTextPaint).width();
    if (temp > textYWdith)
     textYWdith = temp;
   }
   int dp2 = dpToPx(2);
   int dp3 = dpToPx(3);
   xOri = (int) (dp2 + textYWdith + dp2 + xylinewidth);//dp2是y轴文本距离左边，以及距离y轴的距离
//   //X轴文本最大高度
   xValueRect = getTextBounds("000", xyTextPaint);
   float textXHeight = xValueRect.height();
   for (int i = 0; i < xValue.size(); i++) {//求取x轴文本最大的高度
    Rect rect = getTextBounds(xValue.get(i) + "", xyTextPaint);
    if (rect.height() > textXHeight)
     textXHeight = rect.height();
    if (rect.width() > xValueRect.width())
     xValueRect = rect;
   }
   yOri = (int) (height - dp2 - textXHeight - dp3 - xylinewidth);//dp3是x轴文本距离底边，dp2是x轴文本距离x轴的距离
   xInit = interval + xOri;
   minXInit = width - (width - xOri) * 0.1f - interval * (xValue.size() - 1);//减去0.1f是因为最后一个X周刻度距离右边的长度为X轴可见长度的10%
   maxXInit = xInit;
  }
  super.onLayout(changed, left, top, right, bottom);
 }

4、利用ondraw（）方法进行绘制

 @Override
 protected void onDraw(Canvas canvas) {
//  super.onDraw(canvas);
  canvas.drawColor(bgcolor);
  drawXY(canvas);
  drawBrokenLineAndPoint(canvas);
 }

 /**
  * 绘制折线和折线交点处对应的点
  *
  * @param canvas
  */
 private void drawBrokenLineAndPoint(Canvas canvas) {
  if (xValue.size() <= 0)
   return;
  //重新开一个图层
  int layerId = canvas.saveLayer(0, 0, width, height, null, Canvas.ALL_SAVE_FLAG);
  drawBrokenLine(canvas);
  drawBrokenPoint(canvas);
  // 将折线超出x轴坐标的部分截取掉
  linePaint.setStyle(Paint.Style.FILL);
  linePaint.setColor(bgcolor);
  linePaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
  RectF rectF = new RectF(0, 0, xOri, height);
  canvas.drawRect(rectF, linePaint);
  linePaint.setXfermode(null);
  //保存图层
  canvas.restoreToCount(layerId);
 }
 /**
  * 绘制折线对应的点
  *
  * @param canvas
  */
 private void drawBrokenPoint(Canvas canvas) {
  float dp2 = dpToPx(2);
  float dp4 = dpToPx(4);
  float dp7 = dpToPx(7);
  //绘制节点对应的原点
  for (int i = 0; i < xValue.size(); i++) {
   float x = xInit + interval * i;
   float y = yOri - yOri * (1 - 0.1f) * value.get(xValue.get(i)) / yValue.get(yValue.size() - 1);
   //绘制选中的点
   if (i == selectIndex - 1) {
    linePaint.setStyle(Paint.Style.FILL);
    linePaint.setColor(0xffd0f3f2);
    canvas.drawCircle(x, y, dp7, linePaint);
    linePaint.setColor(0xff81dddb);
    canvas.drawCircle(x, y, dp4, linePaint);
    drawFloatTextBox(canvas, x, y - dp7, value.get(xValue.get(i)));
   }
   //绘制普通的节点
   linePaint.setStyle(Paint.Style.FILL);
   linePaint.setColor(Color.WHITE);
   canvas.drawCircle(x, y, dp2, linePaint);
   linePaint.setStyle(Paint.Style.STROKE);
   linePaint.setColor(linecolor);
   canvas.drawCircle(x, y, dp2, linePaint);
  }
 }
 /**
  * 绘制显示Y值的浮动框
  *
  * @param canvas
  * @param x
  * @param y
  * @param text
  */
 private void drawFloatTextBox(Canvas canvas, float x, float y, int text) {
  int dp6 = dpToPx(6);
  int dp18 = dpToPx(18);
  //p1
  Path path = new Path();
  path.moveTo(x, y);
  //p2
  path.lineTo(x - dp6, y - dp6);
  //p3
  path.lineTo(x - dp18, y - dp6);
  //p4
  path.lineTo(x - dp18, y - dp6 - dp18);
  //p5
  path.lineTo(x + dp18, y - dp6 - dp18);
  //p6
  path.lineTo(x + dp18, y - dp6);
  //p7
  path.lineTo(x + dp6, y - dp6);
  //p1
  path.lineTo(x, y);
  canvas.drawPath(path, linePaint);
  linePaint.setColor(Color.WHITE);
  linePaint.setTextSize(spToPx(14));
  Rect rect = getTextBounds(text + "", linePaint);
  canvas.drawText(text + "", x - rect.width() / 2, y - dp6 - (dp18 - rect.height()) / 2, linePaint);
 }
 /**
  * 绘制折线
  *
  * @param canvas
  */
 private void drawBrokenLine(Canvas canvas) {
  linePaint.setStyle(Paint.Style.STROKE);
  linePaint.setColor(linecolor);
  //绘制折线
  Path path = new Path();
  float x = xInit + interval * 0;
  float y = yOri - yOri * (1 - 0.1f) * value.get(xValue.get(0)) / yValue.get(yValue.size() - 1);
  path.moveTo(x, y);
  for (int i = 1; i < xValue.size(); i++) {
   x = xInit + interval * i;
   y = yOri - yOri * (1 - 0.1f) * value.get(xValue.get(i)) / yValue.get(yValue.size() - 1);
   path.lineTo(x, y);
  }
  canvas.drawPath(path, linePaint);
 }
 /**
  * 绘制XY坐标
  *
  * @param canvas
  */
 private void drawXY(Canvas canvas) {
  int length = dpToPx(4);//刻度的长度
  //绘制Y坐标
  canvas.drawLine(xOri - xylinewidth / 2, 0, xOri - xylinewidth / 2, yOri, xyPaint);
  //绘制y轴箭头
  xyPaint.setStyle(Paint.Style.STROKE);
  Path path = new Path();
  path.moveTo(xOri - xylinewidth / 2 - dpToPx(5), dpToPx(12));
  path.lineTo(xOri - xylinewidth / 2, xylinewidth / 2);
  path.lineTo(xOri - xylinewidth / 2 + dpToPx(5), dpToPx(12));
  canvas.drawPath(path, xyPaint);
  //绘制y轴刻度
  int yLength = (int) (yOri * (1 - 0.1f) / (yValue.size() - 1));//y轴上面空出10%,计算出y轴刻度间距
  for (int i = 0; i < yValue.size(); i++) {
   //绘制Y轴刻度
   canvas.drawLine(xOri, yOri - yLength * i + xylinewidth / 2, xOri + length, yOri - yLength * i + xylinewidth / 2, xyPaint);
   xyTextPaint.setColor(xytextcolor);
   //绘制Y轴文本
   String text = yValue.get(i) + "";
   Rect rect = getTextBounds(text, xyTextPaint);
   canvas.drawText(text, 0, text.length(), xOri - xylinewidth - dpToPx(2) - rect.width(), yOri - yLength * i + rect.height() / 2, xyTextPaint);
  }
  //绘制X轴坐标
  canvas.drawLine(xOri, yOri + xylinewidth / 2, width, yOri + xylinewidth / 2, xyPaint);
  //绘制x轴箭头
  xyPaint.setStyle(Paint.Style.STROKE);
  path = new Path();
  //整个X轴的长度
  float xLength = xInit + interval * (xValue.size() - 1) + (width - xOri) * 0.1f;
  if (xLength < width)
   xLength = width;
  path.moveTo(xLength - dpToPx(12), yOri + xylinewidth / 2 - dpToPx(5));
  path.lineTo(xLength - xylinewidth / 2, yOri + xylinewidth / 2);
  path.lineTo(xLength - dpToPx(12), yOri + xylinewidth / 2 + dpToPx(5));
  canvas.drawPath(path, xyPaint);
  //绘制x轴刻度
  for (int i = 0; i < xValue.size(); i++) {
   float x = xInit + interval * i;
   if (x >= xOri) {//只绘制从原点开始的区域
    xyTextPaint.setColor(xytextcolor);
    canvas.drawLine(x, yOri, x, yOri - length, xyPaint);
    //绘制X轴文本
    String text = xValue.get(i);
    Rect rect = getTextBounds(text, xyTextPaint);
    if (i == selectIndex - 1) {
     xyTextPaint.setColor(linecolor);
     canvas.drawText(text, 0, text.length(), x - rect.width() / 2, yOri + xylinewidth + dpToPx(2) + rect.height(), xyTextPaint);
     canvas.drawRoundRect(x - xValueRect.width() / 2 - dpToPx(3), yOri + xylinewidth + dpToPx(1), x + xValueRect.width() / 2 + dpToPx(3), yOri + xylinewidth + dpToPx(2) + xValueRect.height() + dpToPx(2), dpToPx(2), dpToPx(2), xyTextPaint);
    } else {
     canvas.drawText(text, 0, text.length(), x - rect.width() / 2, yOri + xylinewidth + dpToPx(2) + rect.height(), xyTextPaint);
    }
   }
  }
 }

5、点击的处理以及左右

重写ontouchEven()方法，来处理点击和滑动

 @Override
 public boolean onTouchEvent(MotionEvent event) {
  if (isScrolling)
   return super.onTouchEvent(event);
  this.getParent().requestDisallowInterceptTouchEvent(true);//当该view获得点击事件，就请求父控件不拦截事件
  obtainVelocityTracker(event);
  switch (event.getAction()) {
   case MotionEvent.ACTION_DOWN:
    startX = event.getX();
    break;
   case MotionEvent.ACTION_MOVE:
    if (interval * xValue.size() > width - xOri) {//当期的宽度不足以呈现全部数据
     float dis = event.getX() - startX;
     startX = event.getX();
     if (xInit + dis < minXInit) {
      xInit = minXInit;
     } else if (xInit + dis > maxXInit) {
      xInit = maxXInit;
     } else {
      xInit = xInit + dis;
     }
     invalidate();
    }
    break;
   case MotionEvent.ACTION_UP:
    clickAction(event);
    scrollAfterActionUp();
    this.getParent().requestDisallowInterceptTouchEvent(false);
    recycleVelocityTracker();
    break;
   case MotionEvent.ACTION_CANCEL:
    this.getParent().requestDisallowInterceptTouchEvent(false);
    recycleVelocityTracker();
    break;
  }
  return true;
 }

点击的处理是计算当前点击的X、Y坐标范围进行判断点击的是那个点

 /**
  * 点击X轴坐标或者折线节点
  *
  * @param event
  */
 private void clickAction(MotionEvent event) {
  int dp8 = dpToPx(8);
  float eventX = event.getX();
  float eventY = event.getY();
  for (int i = 0; i < xValue.size(); i++) {
   //节点
   float x = xInit + interval * i;
   float y = yOri - yOri * (1 - 0.1f) * value.get(xValue.get(i)) / yValue.get(yValue.size() - 1);
   if (eventX >= x - dp8 && eventX <= x + dp8 &&
     eventY >= y - dp8 && eventY <= y + dp8 && selectIndex != i + 1) {//每个节点周围8dp都是可点击区域
    selectIndex = i + 1;
    invalidate();
    return;
   }
   //X轴刻度
   String text = xValue.get(i);
   Rect rect = getTextBounds(text, xyTextPaint);
   x = xInit + interval * i;
   y = yOri + xylinewidth + dpToPx(2);
   if (eventX >= x - rect.width() / 2 - dp8 && eventX <= x + rect.width() + dp8 / 2 &&
     eventY >= y - dp8 && eventY <= y + rect.height() + dp8 && selectIndex != i + 1) {
    selectIndex = i + 1;
    invalidate();
    return;
   }
  }
 }

处理滑动的原理，就是通过改变第一个点的X坐标，通过改变这个基本点，依次改变后面的X轴的点的坐标。

最后在布局里面应用就可以啦，我就不贴代码啦！

总结：

项目还是有缺点的：

（1）左右滑动时，抬起手指仍然可以快速滑动；代码里面给出了一种解决方案，但是太过于暂用资源，没有特殊要求不建议使用，所以给出一个boolean类型的自定义属性isScroll，true：启动，反之亦然；还有一种解决方案就是外面再加一层横向ScrollView，请读者自行解决，也很简单，只需要稍作修改即可。

（2）点击的时候忘记添加回调，只有添加了回调在可以在activity或者fragment里面获取点击的内容；代码很简单，自行脑补。

项目地址1
项目地址2

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