Set DevExpress Grid Tableview Editable property and determine its parent via RTTI

Question

I have a project with multiple TcxGrids on. The class hierarchy structure of the grids in my project are as follows:

TForm->TPanel->TcxPageControl->TcxTabSheet(subclassed)->TcxGrid->TcxGridLevel->TcxGridDBBandedTableView

In my subclassed TcxTabSheet I have added a new property "ReadOnly" that when set loops over the tabsheets controls and sets them to enabled/disabled respectively.

When a TcxGrid controls enabled property is set to true, the user can no longer interact with the grid at all (including navigating).

It seems I need to set the OptionsData.Editing property on the TcxGridDBBandedTableView to achieve a readonly but still navigable grid control.

Simple enough until you factor in that I want to do this in a loose coupled manner which I think leaves me the option of RTTI.

I have written the following code that loops over the forms controls (looping over the tabs controls or components doesn't give me access to the TcxGridDBBandedTableView). Once the control is found I can set its editing property via RTTI. I just don't seem to able to determine if that TcxGridDBBandedTableView belongs to the TabSheet it sits on.

var
  compIdx: Integer;
begin
  for compIdx := 0 to Pred(ComponentCount) do
    if (Components[compIdx].ClassNameIs('TcxGridDBBandedTableView')) then
      SetOrdProp(GetObjectProp(Components[compIdx], 'OptionsData'), 'Editing', Ord(not FReadOnly));
end;

TL;DR How can I determine what pagectrl tab a cxgrid is on and set its TableView.OptionsData.Editable property without adding any devexpress units to the uses clause of the unit.

the porperty Control which would be necessary to get the cxGrid seems not to be reachable via RTTI. — bummi
What about adding an event for your Readonly property, which could be used in the template of your projects using cxGrid for iterating over contained cxgrids/views. — bummi

David Heffernan David Heffernan · Accepted Answer · 2013-02-08T15:45:42

You are iterating over the components owned by the form. I think that's the wrong approach. You should be looking at the parent/child relationship rather than ownership. Not least because it's perfectly possible for a form to contain controls that it does not own. So, your approach can fail to find controls, particularly dynamically created controls.

So, if you have a tabsheet (or indeed any windowed control), you can iterate over its children like this:

for i := 0 to TabSheet.ControlCount-1 do
  DoSomething(TabSheet.Controls[i]);

If your target grid control is a direct descendent of the tabsheet then this will be enough. If it is more than one level deep in the hierarchy then you will need a recursive solution. I will leave that recursive solution as an exercise for you.

Suppose that you have a control and want to find the tabsheet that it sits inside, then you need to walk up the parent chain. Like this:

function GetParentOfClass(Control: TControl; AClass: TWinControlClass): TWinControl;
var
  Control: TWinControl;
begin
  while Assigned(Control) and not (Control is AClass) do
    Control := Control.Parent;
  Result := TWinControl(Control);
end;

Set DevExpress Grid Tableview Editable property and determine its parent via RTTI

1 Answers