Is it possible to select multiple columns in Virtual Treeview?

Question

I need to add functionality to copy a rectangular selection of nodes and columns, but I can't find any way to actually select multiple columns in a Virtual Treeview (beside toFullRowSelect).

Am I just missing something? And if not, is there a descendant out there with grid-like multicolumn select support?

Answer 1

So after some testing I came up with the following, thanks DiGi for the extra push. DrawSelection won't work with this solution so it needs to be disabled. Since I don't think I'll need to do this again soon I didn't write a descendant.

Set toDisableDrawSelection, toExtendedFocus and toMultiSelect to True.

Declare the following variables/properties somewhere suitable:

StartSelectedColumn: integer;
FirstSelectedColumn: integer;
LastSelectedColumn: integer;
Selecting: boolean;

Update the following events:

OnKeyDown

if (not Selecting) and (Key = VK_SHIFT) then
begin
  StartSelectedColumn := vtMain.FocusedColumn;
  FirstSelectedColumn := StartSelectedColumn;
  LastSelectedColumn := StartSelectedColumn;
  Selecting := true;
end;

OnKeyUp

if Key = VK_SHIFT then
  Selecting := false;

OnFocusChanged

if Selecting then
begin
  if column < StartSelectedColumn then
  begin
    FirstSelectedColumn := column;
    LastSelectedColumn := StartSelectedColumn;
  end
  else if column > StartSelectedColumn then
  begin
    FirstSelectedColumn := StartSelectedColumn;
    LastSelectedColumn := column
  end
  else
  begin
    FirstSelectedColumn := column;
    LastSelectedColumn := column;
  end;
end
else
begin
  StartSelectedColumn := column;
  FirstSelectedColumn := column;
  LastSelectedColumn := column;
end;

OnBeforeCellPaint

if vtMain.Selected[node] and InRange(column, FirstSelectedColumn, LastSelectedColumn) then
begin
  if vtMain.Focused then
    TargetCanvas.Brush.Color := vtMain.Colors.FocusedSelectionColor
  else
    TargetCanvas.Brush.Color := vtMain.Colors.UnfocusedSelectionColor;
  TargetCanvas.Brush.Style := bsSolid;
  TargetCanvas.FillRect(CellRect);
end;

OnPaintText

if vtMain.Selected[node] and InRange(column, FirstSelectedColumn, LastSelectedColumn) then
begin
  if vtMain.Focused then
    TargetCanvas.Font.Color := clHighlightText
  else
    TargetCanvas.Font.Color := vtMain.Font.Color;
end;

Answer 2

One more tip - look at OnStateChange event, maybe you can use

procedure TSomeForm.VTreeStateChange(Sender: TBaseVirtualTree; Enter,Leave: TVirtualTreeStates);
begin
  if tsDrawSelecting in Enter then
  begin
    // Save position
  end;
end;