How to show node image when a TTreeView item is selected
lazarus / 31-LCL

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tintinux · 2022-10-04 11:58

Hi

I display node images, using the property "Images" of my TreeView.

When a node is selected the image disappear on this node.
Is it possible to prevent this ?
Thanks

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d7_2_laz · 2022-10-04 13:02

Probably via property "SelectedIndex"   ... eg.
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i      
 aNode.ImageIndex := 4;       aNode.SelectedIndex := 4;     // or:
 aNode.SelectedIndex := aNode.ImageIndex;

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tintinux · 2022-10-04 13:42

No, this is not a solution.
I was probably not clear enough.
The images are correctly displayed on all tree nodes, but when a node
is selected (either by code or by UI), the image is not visible.

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ASerge · 2022-10-04 14:46

Quote from: tintinux on October 04, 2022, 03:42:37 pmThe images are
correctly displayed on all tree nodes, but when a node is selected
(either by code or by UI), the image is not visible.
The solution from @d7_2_laz is just for such a case.

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d7_2_laz · 2022-10-04 15:05

tintinux, i don't know with which platform and Lazarus version you are
working ..
I can speak for Windows only - no such problem here -; and in this
situation i would try something like:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.TreeView1SelectionChanged(Sender: TObject);begin 
 ShowMessage(inttostr(TreeView1.Selected.SelectedIndex));end;
Now, here either you see a "-1" = no image assigned = nothing will be
displayed
or can inspect the image the SelectedIndex does point to within the
ImageList assigned. Something special with this image?

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tintinux · 2022-11-16 17:09

Hi

I'm on Linux Ubuntu.

My issue is only about the displayed image : when the node is
selected, the image is not shown, when the node is not selected the
image is shown.

I have no problem with SelectedIndex.

I have made a small example attached. Maybe you will see easier the
issue.

Thanks

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tintinux · 2022-11-16 17:14

Quote from: d7_2_laz on October 04, 2022, 05:05:00 pmCode: Pascal
 [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.TreeView1SelectionChanged(Sender: TObject);begin 
 ShowMessage(inttostr(TreeView1.Selected.SelectedIndex));end;
Now, here either you see a "-1" = no image assigned = nothing will be
displayed

You are wrong, I think. Selected.ImageIndex (instead of
Selected.SelectedIndex) returns the image associated to the node. In
my case it doesn't change after node creation.

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wp · 2022-11-16 17:32

Completed your code so that it is working:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.FormCreate(Sender: TObject); begin 
TreeView1.Items.AddChild(TreeView1.Items.Add(nil, 'Node 1'), 'Node
2');  Treeview1.Items[0].ImageIndex:= 0; 
Treeview1.Items[1].ImageIndex:= 0;  TreeView1.Items[0].SelectedIndex
:= 0;  TreeView1.Items[1].SelectedIndex := 0;end;
See: https://lazarus-
ccr.sourceforge.io/docs/lcl/comctrls/ttreenode.selectedindex.html, or
https://docwiki.embarcadero.com/Libraries/Sydney/en/Vcl.ComCtrls.TTree
Node.SelectedIndex

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tintinux · 2022-11-16 17:36

Thanks !