如果我理解正确,您想在X轴上缩放范围的同时也缩放Y轴上的同样范围。如果是这样,可以按照以下方式操作:
void chart1_SelectionRangeChanged(object sender, CursorEventArgs e)
{
// Given the visible (zoomed) range on X,
// it zooms the same relative range on Y:
// i.e. if on the X axis, the range 5% - 30% is zoomed,
// it zooms the same range on Y.
var axisY = this.chart1.ChartAreas[0].AxisY;
var totalXRange = e.Axis.Maximum - e.Axis.Minimum;
var totalYRange = axisY.Maximum - axisY.Minimum;
var ySelectionStart = (e.Axis.ScaleView.ViewMinimum - e.Axis.Minimum) *
totalYRange / totalXRange;
var ySelectionEnd = (e.Axis.ScaleView.ViewMaximum - e.Axis.Minimum) *
totalYRange / totalXRange;
axisY.ScaleView.Zoom(ySelectionStart,ySelectionEnd);
}
正如您所说,事件
AxisValueChanged
并不存在;您链接的帖子可能是指已有的事件
AxisViewChanged。
显然,您也可以使用AxisViewChanged
来达到您的目的,并调整我的代码以利用该事件应该不难。
如果您需要帮助,请随时提问;)
编辑:
我修改了我的代码以满足您的目标。以下代码计算与缩放的X范围内点的最大值和最小值对应的Y范围:
void chart1_SelectionRangeChanged(object sender, CursorEventArgs e)
{
var axisY = this.chart1.ChartAreas[0].AxisY;
var xRangeStart = e.Axis.ScaleView.ViewMinimum;
var xRangeEnd = e.Axis.ScaleView.ViewMaximum;
double? yRangeStart = null;
var pointBeforeRangeStart = this.chart1.Series[0].Points.FirstOrDefault(x => x.XValue <= xRangeStart);
var pointAfterRangeStart = this.chart1.Series[0].Points.FirstOrDefault(x => x.XValue > xRangeStart);
if (pointBeforeRangeStart != null && pointAfterRangeStart != null)
yRangeStart = Interpolate2Points(pointBeforeRangeStart, pointAfterRangeStart, xRangeStart);
double? yRangeEnd = null;
var pointBeforeRangeEnd = this.chart1.Series[0].Points.FirstOrDefault(x => x.XValue <= xRangeEnd);
var pointAfterRangeEnd = this.chart1.Series[0].Points.FirstOrDefault(x => x.XValue > xRangeEnd);
if (pointBeforeRangeEnd != null && pointAfterRangeEnd != null)
yRangeEnd = Interpolate2Points(pointBeforeRangeEnd, pointAfterRangeEnd, xRangeEnd);
var edgeValues = new[] { yRangeStart, yRangeEnd }.Where(x => x.HasValue).Select(x => x.Value);
var valuesInRange = this.chart1.Series[0].Points
.Where(p => p.XValue >= xRangeStart && p.XValue <= xRangeEnd)
.Select(x => x.YValues[0]);
var values = valuesInRange.Concat(edgeValues);
double yMin;
double yMax;
if (values.Any())
{
yMin = values.Min();
yMax = values.Max();
}
else
{
yMin = this.chart1.Series[0].Points.Min(x => x.YValues[0]);
yMax = this.chart1.Series[0].Points.Max(x => x.YValues[0]);
}
axisY.ScaleView.Zoom(yMin, yMax);
}
public static double Interpolate2Points(DataPoint p1, DataPoint p2, double x)
{
var x0 = p1.XValue;
var y0 = p1.YValues[0];
var x1 = p2.XValue;
var y1 = p2.YValues[0];
return y0 + ((x - x0) * y1 - (x - x0) * y0) / (x1 - x0);
}