delphic++buildervirtualtreeview

Virtual Treeview (C++ Builder) 2 icons overlap on Windows 7 but not on XP

I have an issue with VirtualTreeView component on Windows 7. I added a TVirtualStringTree and used OnGetImageIndex event to assign ImageIndex which is always in debugger non-zero value.

VirtualStringTree uses a TImageList with 16x16 icons as Images property.

On Windows XP it works properly and on Windows 7 it overlaps icon with index 0 from TImageList on top of a normal icon. I am running the same program on Windows 7 as on XP so the code is identical, but the drawing is different.

This image illustrates the issue:

virtualtreeview issue

The gray triangle icon has index of 0 and folder icon has index of 5.

Is this a bug in VirtualStringTree? Can I somehow avoid this?

I am using the latest VirtualTreeView version from repository.

Solution

  • In your OnGetImageIndex event handler, pay attention to the Kind: TVTImageKind parameter. Assign ImageIndex as required (typically, this is only for ikNormal and ikSelected values), otherwise assign -1.

    For example, assigning a valid image index when Kind has the value of ikOverlay will cause an overlay image to be drawn over the normal image. (Which may be related to your problem.)