Recently, in order to achieve a system, is through the form after the Panel, drag the meter automatic generation control, but always can't find the header drag events?
I use the Dev CxGrid controls,

As shown in figure, I want to put the red box, drag and drop the meter

And the header in the CxGrid can only drag the Group (Group), or change in a sequence of mouse to move to other places will become not drag,
I try and Drag in the cxGridDBTableView about events, found only on, only to form Drag events recorded, Drag the table header, or invalid,


Think of some way to before a column, the result found column without access to relevant Drag events ,
,

Have 4, 5 hours and had to go to the source code to debug
'Found, click on the header is first performed TCxControl. The MouseDown event, begin the Drag action in this event also really

In this event and get to the class of Drag

As a result, to found the back, TcxGridColumnHeaderMovingObject this class,,, then I'm dizzy,,, can't find the clue,

 procedure TcxGridColumnHeaderMovingObject. CalculateDestParams (AHitTest: TcxCustomGridHitTest; 
The out AContainerKind: TcxGridItemContainerKind; The out AZone: TcxGridItemContainerZone); 
The begin 
Inherited; 
If AContainerKind=ckNone then 
The begin 
AZone:=ViewInfo. GroupByBoxViewInfo. GetZone (AHitTest. Pos); 
If AZone=nil then 
The begin 
AZone:=ViewInfo. HeaderViewInfo. GetZone (AHitTest. Pos); 
If AZone & lt;> Nil then 
AContainerKind:=ckHeader; 
End 
The else 
AContainerKind:=ckGroupByBox; 
end; 
end; 


The function TcxCustomGridController. StartDragAndDrop (const P: TPoint) : Boolean; 
Var 
AHitTest: TcxCustomGridHitTest; 
The begin 
AHitTest:=ViewInfo GetHitTest (P); 
Result:=CanHandleHitTest (AHitTest); 
If the Result then 
The begin 
Result:=AHitTest DragAndDropObjectClass & lt;> Nil; 
If the Result then 
The begin 
CancelHint; 
DragAndDropObjectClass:=AHitTest. DragAndDropObjectClass; 
DragAndDropObject. Init (P, AHitTest); 
end; 
end; 
end; 

Procedure TcxControl. MouseDown (Button: TMouseButton; Shift: TShiftState; X, Y: Integer); 


Procedure TcxControl. CMMouseEnter (var Message: TMessage); 
The begin 
Inherited; 
If the Message. The lParam=0 then 
MouseEnter (Self) 
The else 
MouseEnter (TControl (Message. LParam)); 
end; 


Procedure TcxDragAndDropObject. DragAndDrop (const P: TPoint; Var Accepted: Boolean); 
The begin 
Dirty:=False; 
Screen. The Cursor:=GetDragAndDropCursor (Accepted); 
end; 


Procedure TcxControl. DoMouseEnter (AControl: TControl); 
The begin 
If ((AControl=Self) or (AControl=nil)) and (FMouseEnterCounter=0) then 
The begin 
Inc (FMouseEnterCounter); 
DxCallNotify (FOnMouseEnter, Self); 
end; 
end; 

This is me out I think is the key code,,
I also try to through the header when the drag and drop, the cursor changes, to find a key code, the result is no harvest,
And, up to now I didn't understand first, who will go to trigger TcxControl. MouseDown event? The Column is not TcxControl class, not a TableView,
Only CxGrid1 ancestor class is TCxControl, but why am I in the MouseDown event CxGrid1, unable to capture?


After this the way to give up, I want to by intercepting Windows mouse messages to achieve a goal, messages can be intercepted, but has been unable to determine, whether the Column Column is in the condition of dragged,

Want to consult everybody a great god, and what method did not

CodePudding user response:

HotTrack properties!