Converts from a canvas pixel coordinate to a chart axis coordinate. Based on the ZoomMinimum and ZoomMaximum range of the chart axis, this routine converts the parameter value into a chart axis coordinate. Unlike the overloaded PixelToAxis method, this method assumes that the visual pixel range of the chart axis is defined by the chart panel's ChartRect property (obtained through the Owner property). The chart axis uses the bounds of the rectangle that apply to its location, e.g., a BottomAxis chart axis would use the ChartRect's Left=ZoomMinimum and Right=ZoomMaximum fields for the calculation (the rectangle is also adjusted if StartPosition and EndPosition properties are not their defaults).
Use one of the PixelToAxis methods anytime you need to convert from a canvas pixel coordinate to the internal chart axis coordinates. For example, if the chart axis has a zoomed range from 0 to 100 and the ChartRect is Left=150 and Right=500, this function would return:
PixelToAxis( 150 ) = 0
PixelToAxis( 325 ) = 50
PixelToAxis( 500 ) = 100
Use one of the AxisToPixel methods to convert back from chart coordinates to canvas pixel coordinates.
Namespace: FMX.RS.ChartPanel
Delphi |
public |
Parameters
Value
Type: TCanvasPixel
IgnoreZoom
Type: Boolean
Type: TRSChartValueType
The following code displays the chart axes' coordinates for the point under the mouse: Delphi |
procedure TForm1.RSChartPanel1MouseMove(Sender: TObject; |
The following code does the same thing for the paint box:
Delphi
procedure TForm1.PaintBox1MouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
with Sender as TPaintBox do
Self.Caption := 'X='+FloatToStr(RSChartPanel1.BottomAxis.PixelToAxis(X, Canvas.ClipRect)) + ' ' +
'Y='+FloatToStr(RSChartPanel1.LeftAxis.PixelToAxis(Y, Canvas.ClipRect));
end;
Reference |
