TdxChartHitTest Class

Stores Chart control HitTest information.

Declaration

TdxChartHitTest = class(
    TObject
)

Remarks

HitTest information allows you to identify and access the inspected visual element (that is, a visual element at the current mouse pointer position or at the coordinates passed to the CalculateHitTest procedure) within the Chart control client area.

Chart HitTest information updates every time when:

• The OnHotTrackElement or OnMouseMove event occurs. The inspected point matches the current mouse pointer position.
• You call the CalculateHitTest procedure. The procedure’s X and Y parameters define inspected point coordinates within the Chart control client area.

Main API Members

The list below outlines key class members that allow you to identify visual elements.

Point

Returns pixel coordinates of the inspected point within the Chart control’s client area.

HitCode

Identifies the Chart control’s visual element to which the inspected point belongs.

Argument | Value

Return the coordinates of the inspected point within the plot area of an XY diagram in corresponding axis measurement units.

InPlotArea

Identifies if the inspected point is within the plot area of an XY diagram.

Series | SeriesPoint | SeriesValueLabel

Provide access to inspected series and their visual elements.

Title

Provides access to the axis, chart, diagram, legend, or series title to which the inspected point belongs.

Legend | LegendItem

Provide access to inspected legend panes and items.

Axis | AxisValueLabel

Provide access to inspected axes and their value labels.

TotalLabel

Provides access to the series total label to which the inspected point belongs.

Diagram

Provides access to the diagram to which the inspected point belongs.

Code Example

The following code example demonstrates an OnMouseMove event handler that displays mouse pointer coordinates (in axis measurement units) in the application form caption:

Delphi

uses dxChartControl;
// ...
procedure TMyForm.dxChartControl1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
begin
  if dxChartControl1.HitTest.Diagram <> nil then
  begin
    if (dxChartControl1.HitTest.Argument <> VarNull) and (dxChartControl1.HitTest.Value <> VarNull) then
    Caption := Caption + 'X: ' + VarToStr(dxChartControl1.HitTest.Argument) +
      ' Y: ' + VarToStr(dxChartControl1.HitTest.Value);
  end;
end;

C++

#include "dxChartControl.hpp"  
// ...
void __fastcall TMyForm::dxChartControl1MouseMove(TObject *Sender, TShiftState Shift, int X, int Y)
{
  if(dxChartControl1->HitTest->Diagram != nullptr)
  {
    if((dxChartControl1->HitTest->Argument != VarNull) && (dxChartControl1->HitTest->Value != VarNull))
      Caption = Caption + "X: " + VarToStr(dxChartControl1->HitTest->Argument) +
        " Y: " + VarToStr(dxChartControl1->HitTest->Value);
  }
}

Direct TdxChartHitTest Class References

The following public API members reference a TdxChartHitTest object:

TdxCustomChartControl.HitTest

Provides access to HitTest information on the inspected point within the Chart control client area.

TdxChartHotTrackElementEventArgs.HitTest

Provides access to HitTest information on the currently hot-tracked visual Chart element.

TdxChartHotTrackElementEventArgs.PreviousHitTest

Provides access to HitTest information on the visual Chart element that was hot-tracked before the current OnHotTrackElement event occurrence.

Inheritance

TObject

TdxChartHitTest