Tab key causes NullReferenceException with Hydra WinForms host and Delphi visual plugin

Hydra
1

When my Delphi visual plugin has focus within a WinForms HostPanel and I press the tab key, I get the following exception:

System.NullReferenceException: Object reference not set to an instance of an object.
   at RemObjects.Hydra.HostPanel.ProcessTabKey(Keys KeyData)
   at RemObjects.Hydra.HostPanel.ProcessDialogKey(Keys keyData)
   at System.Windows.Forms.Control.PreProcessMessage(Message& msg)
   at System.Windows.Forms.Control.PreProcessControlMessageInternal(Control target, Message& msg)
   at System.Windows.Forms.Application.ThreadContext.PreTranslateMessage(MSG& msg)

Do you know of a reason for this? I can press other special keys, like the arrow keys, and they work. My Delphi visual plugin is a THYVisualPlugin. I’m using the latest version of Hydra (5.0.91.1169).

2

Hello

Could you send to support@ a testcase where this issue reproduces?

Thanks in advance.

3

I sent an email with a zip attachment to support@remobjects.com. The archive contains two projects demonstrating the issue I have, a Delphi visual plugin and WinForms host. Please let me know if you got it.

4

The testcase has been received. I’ll post an answer here once the cause of the issue is found.

5

Hello

Assigning plugin to the host panel as

(fCurrentPlugin as IHYCrossPlatformVisualPlugin).ShowParented(hostPanel1.Handle);

doesn’t properly initialize internal host panel’s structures so it cannot perform its duties on handling special events like Tab press.

You should assign plugin to the panel as

hostPanel1.HostPlugin(fCurrentPlugin as IBasePlugin);

Also please consider adding OnProcessTabKey event handler to the plugin if you need special plugin handling plugin-side.

Regards

6

Thank you, that fixed the issue. Sorry for the trouble (it’s my first time with WinForms host and Delphi visual plugins).