I wrote a series of articles last year on this, with source code. VMware and Wine detection are here. Virtual PC is here. All three of these have pretty iron-clad detection because there are documented callbacks to the hypervisor (in the case of Wine, an extension to a standard DLL). I put up an untested … Read more
Scrolling origins An action with the mouse wheel results in a WM_MOUSEWHEEL message being sent: Sent to the focus window when the mouse wheel is rotated. The DefWindowProc function propagates the message to the window’s parent. There should be no internal forwarding of the message, since DefWindowProc propagates it up the parent chain until it … Read more
What ever scheme you use, it may be handy to know that you can actually rename a running .exe file. So rename file, copy in new file works nice. And the next time someone launch the program they will launch a the new version. This is ofcourse very handy in enviroment where many users run … Read more
Let us consider the following three type declarations: TProcedure = procedure; TMethod = procedure of object; TAnonMethod = reference to procedure; These are all very similar to each other. In terms of calling instances of each of these three types, the calling code is identical. The differences arise in what can be assigned to variables … Read more
Take a closer look at TTabControl / TTabItem in the unit FMX.TabControl. This is your perfect example because it basically needs to solve the same problem. The following function is what you need to override: procedure DoAddObject(const AObject: TFmxObject); override; This is called when a control is added to your control. Override this function so … Read more
This is from long ago as an escape character to enable you to have consts for control characters in a more readable way. const CtrlC = ^C; begin Write(Ord(CtrlC)); end. This defines a Char constant with value #3, then writes 3 in Borland Pascal 7, and I remember seeing it years before that too. I … Read more
Well, it’s hard to be sure without a lot of testing, but it certainly looks like this is a bug, either in TThreadedQueue or in TMonitor. Either way it’s in the RTL and not your code. You ought to file this as a QC report and use your example above as the “how to reproduce” … Read more
RTTI in Delphi is still not quite as full-featured as Reflection in .NET or other managed languages, because it is operating on compiled code, not an Intermediate Language (bytecode). However, it is a very similar concept, and the new RTTI system in Delphi 2010 brings it a lot closer to reflection, exposing an entire object-oriented … Read more
As ever so often Zarco Gajic has a solution: Capture the output from a DOS (command/console) Window. This is a copy from his article for future reference: The example runs ‘chkdsk.exe c:\’ and displays the output to Memo1. Put a TMemo (Memo1) and a TButton (Button1) on your form. Put this code in the OnCLick … Read more
To summarize, the problem happens only with published interface properties that have a getter method, and the property points to component on another form/module (and that form/module is not recreated yet). In such case restoring form DFM causes an AV. I’m pretty sure the bug is in the ASM code in GetOrdProp, but it’s beyond … Read more