以编程方式滚动图表

Question

我的WinForm上有一个图表，显示来自生命体征监测仪的心电图信号。该图表在X轴上有一个滚动条，用户可以在任意点来回滚动以查看信号。这很管用。图表会实时更新。

图表中的数据在表单加载时显示。我遇到的问题是，如果用户关闭并重新打开表单，滚动条按钮会重置到最左边。我希望滚动条按钮位于图表中等于当前DateTime的点，但我无法通过查看图表控件找到任何方法。谷歌搜索并不成功。

这是我的图表设置：

private void InitializeChartEKG() {
chartEKG.ChartAreas[0].AxisX.Title = "Time";
chartEKG.ChartAreas[0].AxisX.MajorTickMark.Enabled = true;
chartEKG.ChartAreas[0].AxisX.MinorTickMark.Enabled = true;
chartEKG.ChartAreas[0].AxisX.IsStartedFromZero = true;
chartEKG.ChartAreas[0].CursorX.LineColor = Color.LawnGreen;
chartEKG.ChartAreas[0].CursorY.LineColor = Color.LawnGreen;
chartEKG.ChartAreas[0].AxisX.MajorGrid.Enabled = true;
chartEKG.ChartAreas[0].AxisX.MajorGrid.Interval = 100;
chartEKG.ChartAreas[0].AxisX.IsStartedFromZero = true;  
chartEKG.ChartAreas[0].AxisX.MajorTickMark.Enabled = true;
chartEKG.ChartAreas[0].AxisX.Minimum = 0;
chartEKG.ChartAreas[0].AxisY.Maximum = 600;
chartEKG.ChartAreas[0].AxisY.Minimum = -600;
chartEKG.ChartAreas[0].AxisX.Interval = 10000;
chartEKG.ChartAreas[0].AxisY.Title = "mV";
chartEKG.Series[0].XValueType = ChartValueType.DateTime;
chartEKG.Series[0].YValueType = ChartValueType.Int32;
chartEKG.ChartAreas[0].AxisX.IntervalType = DateTimeIntervalType.Auto;
chartEKG.ChartAreas[0].AxisX.LabelStyle.IntervalType = DateTimeIntervalType.Auto;
chartEKG.ChartAreas[0].AxisX.LabelStyle.Format = "HH:mm:ss tt";
chartArea = chartEKG.ChartAreas[0];
chartArea.AxisX.ScaleView.SizeType = DateTimeIntervalType.Auto;
int position = 0;
int blockSize = 10000;
int size = blockSize;
chartArea.AxisX.ScaleView.Zoom(position, size);
chartArea.AxisX.ScaleView.SmallScrollSize = blockSize;
chartArea.CursorX.AutoScroll = true;
chartArea.AxisX.ScrollBar.BackColor = Color.LightGray;
chartArea.AxisX.ScrollBar.ButtonColor = Color.LightSteelBlue;
chartArea.AxisX.ScrollBar.LineColor = Color.DarkBlue;
chartArea.AxisX.ScrollBar.ButtonStyle = ScrollBarButtonStyles.SmallScroll;
CultureInfo culture = new CultureInfo("en-US");
}

在我调用的方法中添加我认为可以做的点：

chartEKG.Invoke(new Action(() => chartEKG.ChartAreas[0].AxisX.ScaleView.Position = chartEKG.ChartAreas[0].AxisX.Maximum - SomeNumber);  

但我不知道如何计算SomeNumber

Answer 1

终于找到了解决方案。在将点添加到图表的方法中，我修改了添加点的循环：

foreach (string point in count) {
try {
time = time.AddMilliseconds(2);
chartEKG.Invoke(new Action(() => series1.Points.AddXY(time, Convert.ToDouble(point) * 0.61)));
}
catch (ArgumentException) { }
loopCount = loopCount + 1;
string timeFormat = "yyyyMMddHHmmssfff";
string timeNow = DateTime.Now.ToString(timeFormat);
if (time == DateTime.ParseExact(DateTime.Now.ToString(timeNow), timeFormat, CultureInfo.InvariantCulture)) {
loopToStopAt = loopCount;
}
}

然后在foreach循环下面，我放置了以下代码：

chartEKG.Invoke(new Action(() => chartEKG.ChartAreas[0].AxisX.ScaleView.Scroll(chartEKG.ChartAreas[0].AxisX.Maximum - Convert.ToDouble(loopToStopAt))));

这将以编程方式将滑块拖动到图表的最右侧，这正是我想要的。