我正在嘗試將 MS Chart 與自定義控制元件一起使用。我的目的是：
- 將滑鼠懸停在該段上時，僅突出顯示連接兩個相鄰點的線段
- 查找這兩個相鄰點的索引（我需??要能夠通過同時移動兩個點來拖動該線）
插圖種類： 
現在，我可以使用此處描述的方法檢測圖表上某條線上的懸停。但是我一直在尋找索引或至少是這兩個點的坐標。
uj5u.com熱心網友回復：
所以這個問題的最初想法是通過 x 找到最近的點（假設所有系列的 x 值確實在穩步增加），然后計算 y 值。但是我對它進行了一些改進，并增加了對完全垂直線的支持。所以這是我用于捕獲所需行的代碼：
private static GrippedLine? LineHitTest(Series series, double xPos, double yPos, Axis xAxis, Axis yAxis)
{
double xPixelPos = xAxis.PixelPositionToValue(xPos);
double yPixelPos = yAxis.PixelPositionToValue(yPos);
DataPoint[] neighbors = new DataPoint[2];
neighbors[0] = series.Points.Last(x => x.XValue <= xPixelPos);
neighbors[1] = series.Points.First(x => x.XValue >= xPixelPos);
DataPoint[] verticalMates;
foreach (DataPoint neighbor in neighbors)
{
if (Math.Abs(neighbor.XValue - xPixelPos) < LINE_GRIP_REGION)
{
verticalMates = series.Points.FindAllByValue(neighbor.XValue, "X").ToArray();
if (verticalMates.Length > 1)
{
if (verticalMates.Length > 2)
{
if (verticalMates[0].YValues[0] < verticalMates[verticalMates.Length - 1].YValues[0])
{
neighbors[0] = verticalMates.LastOrDefault(y => y.YValues[0] < yPixelPos);
neighbors[1] = verticalMates.FirstOrDefault(y => y.YValues[0] >= yPixelPos);
}
else
{
neighbors[0] = verticalMates.LastOrDefault(y => y.YValues[0] > yPixelPos);
neighbors[1] = verticalMates.FirstOrDefault(y => y.YValues[0] <= yPixelPos);
}
}
else
{
neighbors[0] = verticalMates[0];
neighbors[1] = verticalMates[1];
}
break;
}
}
}
double x0 = xAxis.ValueToPixelPosition(neighbors[0].XValue);
double y0 = yAxis.ValueToPixelPosition(neighbors[0].YValues[0]);
double x1 = xAxis.ValueToPixelPosition(neighbors[1].XValue);
double y1 = yAxis.ValueToPixelPosition(neighbors[1].YValues[0]);
double Yinterpolated = y0 (y1 - y0) * (xPos - x0) / (x1 - x0);
int[] linePoints = new int[2];
// if mouse Y position is near the calculated OR the line is vertical
if (Math.Abs(Yinterpolated - yPos) < LINE_GRIP_REGION || neighbors[0].XValue == neighbors[1].XValue)
{
linePoints[0] = series.Points.IndexOf(neighbors[0]);
linePoints[1] = series.Points.IndexOf(neighbors[1]);
}
else
{
return null;
}
return new GrippedLine()
{
startLinePointIndex = linePoints[0],
endLinePointIndex = linePoints[1],
x0Correction = neighbors[0].XValue - xPixelPos,
y0Correction = neighbors[0].YValues[0] - yPixelPos,
x1Correction = neighbors[1].XValue - xPixelPos,
y1Correction = neighbors[1].YValues[0] - yPixelPos
};
}
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