Lazarus

Programming => General => Topic started by: bobonwhidbey on June 13, 2021, 07:58:10 pm

Title: VirtualStringTree and PaintText
Post by: bobonwhidbey on June 13, 2021, 07:58:10 pm

I'm just starting to learn about all the amazing capabilities of TVirtualStringTree. I think a whole book might be written on it with all it's properties and options. I'd like to be able to "paint" the text area. I was hoping that something like this in onPaintText would work.

Code: Pascal  [Select][+][-]

1.     Data := VST.GetNodeData(Node);
2.     TargetCanvas.TextOut(x,y,Data.Text);

In this manner I could have some of the text in one color, and some in another. I also need to stop the text from being painted by the component.

Title: Re: VirtualStringTree and PaintText
Post by: winni on June 13, 2021, 08:20:36 pm

Hi!

Look at  the example page of VirtualTreeView and look at the onPaintText section:

https://wiki.freepascal.org/VirtualTreeview_Example_for_Lazarus (https://wiki.freepascal.org/VirtualTreeview_Example_for_Lazarus)

Winni

Title: Re: VirtualStringTree and PaintText
Post by: balazsszekely on June 13, 2021, 08:23:25 pm

@bobonwhidbey

Quote

I'm just starting to learn about all the amazing capabilities of TVirtualStringTree. I think a whole book might be written on it with all it's properties and options. I'd like to be able to "paint" the text area. I was hoping that something like this in onPaintText would work.

Try something like this:

Code: Pascal  [Select][+][-]

1. type
2.   PData = ^TData;
3.   TData = record
4.     FBold: Boolean;
5.     FColored: Boolean;
6.   end;
7.  
8. procedure TForm1.VSTPaintText(Sender: TBaseVirtualTree;
9.   const TargetCanvas: TCanvas; Node: PVirtualNode; Column: TColumnIndex;
10.   TextType: TVSTTextType);
11. var
12.   Data: PData;
13. begin
14.   if TextType <> ttNormal then
15.     Exit;
16.   Data := VST.GetNodeData(Node);
17.   case Column of
18.     -1: begin //if no columns are defined, the case is not needed
19.          if Data^.FBold then
20.            TargetCanvas.Font.Style := TargetCanvas.Font.Style + [fsBold];
21.  
22.          if Data^.FColored then
23.            if Node = Sender.FocusedNode then
24.              TargetCanvas.Font.Color := VST.Colors.SelectionTextColor
25.            else
26.              TargetCanvas.Font.Color := clRed;
27.        end;
28.     0: begin
29.          //each column has different font
30.        end;
31.     end;
32. end;
33.  
34. procedure TForm1.Button1Click(Sender: TObject);
35. var
36.   Node: PVirtualNode;
37.   Data: PData;
38. begin
39.   Node := VST.AddChild(nil);
40.   Data := VST.GetNodeData(Node);
41.   Data^.FBold := True;
42.   Data^.FColored := False;
43.  
44.   Node := VST.AddChild(nil);
45.   Data := VST.GetNodeData(Node);
46.   Data^.FBold := False;
47.   Data^.FColored := True;
48. end;    

Title: Re: VirtualStringTree and PaintText
Post by: bobonwhidbey on June 13, 2021, 08:45:21 pm

The examples and GetMem's approach seem to require that the text for the entire column must use the same font attributes. I want to have some text in one color/style and other parts of the text in another.

Title: Re: VirtualStringTree and PaintText
Post by: balazsszekely on June 13, 2021, 08:54:20 pm

@ bobonwhidbey

Quote

The examples and GetMem's approach seem to require that the text for the entire column must use the same font attributes. I want to have some text in one color/style and other parts of the text in another.

If you wish to have full control over the drawing then VirtualDrawTree is a much better option. You can find an example in the following post(see attachment):
https://forum.lazarus.freepascal.org/index.php/topic,37834.msg257241.html#msg257241

Please check the VDTDrawNode event.