Jvcl Delphi 11

[Joslyn Moreci]

JVCLis a library of more than 600 Delphi visual and non-visual components ( -jedi/jvcl). Although heavily Windows-centered, some of them have been ported to Lazarus. This page intends to give a summary of the JVCL components available for Lazarus. Some of the info snippets were taken from -jedi.org/wiki/JVCL_Component_Overview.

Due to the large number of components the original Delphi version is split into a variety of packages. The Lazarus port follows this convention because the user can install only the functionality needed.

For each package, a runtime and designtime version is available. Runtime packages can be identified with an appended R, designtime packages with an appended D. In the requirements for a project always use the runtime package.

The developers version of the Lazarus port is available via svn from -ccr/svn/HEAD/tree/components/jvcllaz/. The current release version can be downloaded from -ccr/files/jvcllaz/; it is also offered by the Lazarus Online Package Manager.

Project JEDI, namely the Jedi Code Library (jcl) and Jedi Visual Components Library (jvcl) use a numbering scheme for their packages based on the Delphi versions (as indicated by the VERxxx conditional defines). Since it is easy to get confused, here is a table of these values:

Today I had a rather annoying problem with Delphi XE2. I only wanted to change the caption of a TListView column using the Columns Editor (right click -> Columns Editor). The IDE crashed on me with an Access Violation. So, I thought I had broken it again (things like this happen when you are developing IDE plugins) and uninstalled GExperts. After a restart I tried it again and got the same Access Violation, proving at least that GExperts was not the culprit.

So, which other IDE plugins were installed? To find out, I opened the Help -> About dialog, which immediately crashed on me with an Access Violation. It happened while it was drawing the list of Installed Products.

I restarted the IDE again and looked into the About Dialog. There were only the Embarcadero Quality Insight and the JEDI Visual Component Library left. No crash occurred. I reloaded the project, opened the About Dialog again and got the now familiar Access Violation. WTF? Could it be the JVCL?

I renamed the JvCore160.bpl package that all jvcl packages load. And tried again. I got lots of error messages when I started the IDE and again when I opened my project, but I could successfully open the About Dialog.

I made the JvCore160.bpl package available again, restarted the IDE, but this time created a new VCL project and added a JVCL component to it. I opened the About Dialog and got the AV. I guess that proved the point.

That was when I remembered reading about Delphi 2005 (and later) loading packages on demand instead of on startup. This explains why the AV happens only after a JVCL component was used in a project: Because otherwise the packages simply were not loaded at all.

I went to GitHub, downloaded the latest ZIP files from all three projects, put everything together and installed JCL and JVCL to Delphi XE2 (the JCL installer dialog looks intimidating if you have got 18 versions of Delphi installed). I then had to remove the directories from the library paths again and compile several of my packages that need the JCL or JVCL+JCL, which required me to make some small changes to my code. But it took only about half an hour, which is nothing compared to the several hours I had already wasted trying to find out what made Delphi XE2 crash.

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