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I have to port a project from Borland C++ Builder 5.0 under Windows XP to Qt 4.7.1 using g++ under Windows 7/mingw. The libraries and command-line utilities are done, and now I have to tackle the GUI applications, which use Borland VCL.
Can anybody recommend any tools or libraries to make this task easier?
Does anybody have any experience of this?

Edited to add: Well, I took the bull by the horns, and implemented the GUI from scratch. And I have to say, the commentators were right: I can't see any way of using the existing Borland GUI to ease the process.

TonyK
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  • How many forms your C++Builder GUIs have? Only a few, dozens, hundreds? As you probably know, you get the best results if you create the Qt GUIs from scratch. –  Jan 07 '11 at 16:50
  • A few dozen forms. Some of them are quite complicated, with tree views, tabs etc. So I don't want to create them all from scratch if I can avoid it. – TonyK Jan 07 '11 at 16:53
  • I've been wondering when someone asks this very question :) Automatic conversion from VCL to Qt does not seem to be feasible task, however. – Piotr Dobrogost Jan 07 '11 at 20:05

3 Answers3

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There are several big differences between VCL and Qt that will make an automatic conversion process quite difficult.

  • Qt uses signals and slots and inheritance where VCL uses events.
  • VCL components use absolute coordinates and Qt uses layouts. Of course, you could use absolute coordinates also with Qt, but the GUIs would be quite awful then.
  • VCL's TListBox and TTreeView classes are quite different from Qt's View and Model classes (although you could use QListWidget and QTreeWidget instead).

I guess it is much faster to design totally new GUIs with Qt than to create even a mediocre VCL-to-Qt converter. And the code will be much easier to maintain. I suggest that you take one VCL form of medium complexity and recreate that with Qt. After that you can make an estimation of the total recreation work. Also you will have a better understanding about the feasibility of a conversion tool, which you most probably would need to make by yourself.

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Someone has written a tool to convert dfm's to qt ui files:

http://sourceforge.net/projects/dfm2qt4ui/

Its has a few small bugs but it can save several hours of time porting form designs. In some cases redesigning specific forms is preferable - but in many cases, having labels and roughly equivalent controls positioned for you saves a lot of point-and-click action.

Pete
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  • Tried the tool. The result did not satisfy me at all. I see that the best way to port the project is implementing GUI from scratch as the author said. – vrogach Nov 25 '14 at 10:43
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    Totally depends on the number of controls on the form etc. It has saved me a lot of work but still the .ui files require a lot of re-organizing. But at least the controls have the same variable names and have been added to the forms already. A complete rewrite will always introduce lots of new bugs. – Pete Nov 26 '14 at 13:48
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I agree with the current consensus that automatic conversion from VCL to QT is not a good idea because the concept behind both is very different, and you are much better off learning "the QT way" and using that from the start.
However there is one major step that nobody has yet mentioned: refactoring! Before starting, make sure you refactor the original forms to remove as much business logic as possible and leave only what is really GUI code. It depends on how good your architecture already is of course, but the VCL designer tends to encourage putting as much as possible in forms (even going as far as having invisible "data forms" with non-visual components!), so you often find a lot of stuff in the form that shouldn't be there.

RobinP
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