John Dorlon

Hello, I am using Delphi version 11.1 and TVirtualStringTree version 7.6.1. I have created a very simple test project, just dropping a TEdit and TVirtualStringTree on a form, adding a node to VST so it paints some text. When I set project options -> DPI Awareness to "GDI scaling" and run my project on a 4K display with 200% scaling, the VST shows pixelated and the TEdit shows it smooth. In my "real" app, almost all controls show the text smoothly, but VST does not. Does anyone know why? I have attached a sample app and some screen shots. Thanks. John project1.zip

Hi again Vincent. I think I solved it by using a TControlCanvas for the buffering instead of TBitmap.Canvas. This code scales the text nicely under GDI Scaling. I only changed TBaseVirtualTree.PaintTree. You can search for "Dorlon" to see my changes, and I left the old code there, commented out. Please let me know what you think. Thanks again John Edit: Hmm, actually, this change is only fine and not flickery when I mouse over nodes. When I mouse over the column headers, the nodes flicker and look like they are painted twice with a small offset the 2nd time. 😞 I think I'm getting close though. TBaseVirtualTree.PaintTree.pas

Hi Vincent, Thank you for the reply. I first tried with Per Monitor V2, but my app (with hundreds of forms) is MDI. In general, I got the app looking good right by setting the ParentFont and Scaling props. But we've also got all combinations of imbedded forms, docked forms, fsStayOnTop, and I had a long list of problems to fix. For example, a particular form looks great as a normal MDI Child, but when the same form is embedded in a fsStayOnTop form, everything is too small. With GDI, I just have 2 problems to fix. VST and images (which are the right size, just pixely) Back to GDI - I see what you mean about the bitmaps. I found them in the TBaseVirtualTree.PaintTree procedure. If I include poUnbuffered in the PaintOptions, then I see it painting smoothly. Of course, that makes it flicker too. I wonder if there is any other way to prevent flicker. Maybe we could use a TControlCanvas instead of NodeBitmap.Canvas? Or maybe there is some way to get the OS to scale on NodeBitmap's canvas? Thanks for all your contributions to the Delphi world. -John