Running nightly Eclipse for the impatient

 

Eclipse-Icon.png

If you’re an Eclipse developer, you might consider running a nightly version of Eclipse so that you can easily test out the latest patches. Bleeding edge is the cool stuff right? It’s actually surprisingly quite stable.

The advantage of this setup is that you won’t have to re-download a new version and re-download all the plugins over and over. You just configure the thing once and just click on ‘check for updates’ once in a while.

The setup is a little bit counter intuitive. This article is not just ‘follow these steps’, but more about understanding the mechanism and workflow.

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MatterMost native chat client (like slack/IRC) on Linux

 

So today I bumped into https://mattermost.eclipse.org 

This is like slack (sort of modern IRC) but open source.

I also found that is has a Linux Native client:
https://about.mattermost.com/downloads/

To get it to work, I just downloaded it, extracted it and ran the included “Mattermost” binary.

Connecting it to Eclipse was mildly counter intuitive.

When faced witht he ‘Teams’ dialogue, I thought I had to  type in Name OR URL, but it turns out you type in both. The name is just an alias ex “Eclipse”, and for URL you put in:

https://mattermost.eclipse.org/

Ex:
Selection_046.png

After you joined, you can find some channels to join. In my case:

Platform: SWT

Now when someone wants to chat with you, you can give them the URL:
https://mattermost.eclipse.org/eclipse/channels/platform-swt

Happy MatterMost-ing

Eclipse, Dark theme and Gtk. What Eclipse can theme and what needs to be themed by the OS.

 

About

I’m an SWT developer on the Gtk side.

Recently I’ve done a fair bit of work with Eclipse’s dark theme and Gtk’s CSS. (E.g fixing background of button and combo). As such I’ve come across what is do-able in SWT and what is not.

 

The issue with composed GtkWidgets

In SWT, we can theme individual GtkWidgets with gtk_context_add_provider(widgetProvider, css) . E.g basic labels, buttons. This works well for basic widgets.

However, some gtk widgets are composed of multiple nested widgets. E.g: GtkComboBoxText

GtkComboBoxText
— GtkToggleButton
— GtkTreeMenu
— GtkCellView
— etc..

The issue is that the CSS that we apply only get’s applied to the top-level widget and not always recursively to all it’s child widgets. (Please see 1* in appendix)

With such widgets, we can sometimes use gtk_bin_get_child() to get one of the nested components and run gtk_context_add_provider(..) on that, but this doesn’t give us access to all nested components. (bin_get_child returns only one child).
Sometimes we can hack a bit and with gtk_container_forall(..) access the child widgets that gtk_bin_get_child() does not expose.

But there is a limit as to what we can access. Some inner widgets are tucked away inside a private struct (the issue described here). As such, we have no way to apply a style context to them.

As a result, we can sometimes only apply a background color to some parts of the widget.
In the example below, we styled the Entry and the text of the menu. But the drop down button and the background of the menu cannot be styled.

MenuComboBox_2015.04.07

 

How do other Gtk Developers do it?

You might wonder, with such a limitation, how do other gtk developers get by?
Suppose you’d like to have two combo boxes, a blue and a red one. How would a Gtk Developer implement this?

To find the answer to this mystery I ventured out to the gtk+ irc channel and a guy called ‘Company’ helped me out.
To apply a theme to individual widgets in Gtk3, you would have to give them a unique class ID, then create a provider for the whole screen and select the widget based on it’s unique ID.

I wrote some native Gtk code to try it out and it worked. (In the example I assign an id ‘custom-class-123’ and then theme it from the global theme.

Technically, implementing this in SWT wouldn’t be difficult. But this would be a hack on an a somewhat epic scale. It would mean we would have 1000’s of unique CSS classes to deal with and it’s not yet obvious if it would be possible to remove styling once applied.

The main issue is that SWT’s philosophy is to style each and individual widget, there isn’t really a ‘central’ theming api. Where as Gtk3’s philosophy is to define the CSS only once and be done with it. E.g GtkComboBoxText * { background:red }  and for individual widget styling use CSS classes.

 

So what’s the deal with Check/Radio/Slider icons?

Eclipse has it’s own CSS syntax which differs from GTK. You can’t really take Eclipses’ Dark-theme CSS and just bluntly apply it to Gtk.

For example in Eclipse CSS ‘Label’ and ‘Button’ are defined, but in Gtk CSS this would need to be translated to GtkLabel and (GtkButton|GtkToggleButton|GtkRadioButton|GtkCheckButton [depending on SWT.STYLE bit]).

With that said, Eclipse CSS does not define any icons for GtkCheckButton, GtkRadioButton or sliders. As a result, we get the icons from the underlying GtkTheme if any are defined.

So when the OS has dark icons, Eclipse looks like this: (note the dark check-boxes):

And when the OS has bright icons, Eclipse looks like this:

But if the theme doesn’t define icons, then we draw our own, then it looks like this:

 

Conclusion: So how do we get Eclipse to look nice?

In essence, Eclipse’s theming doesn’t fully live on it’s own. It takes some things from the OS Gtk theme (e.g radio icons, Menu backgrounds in Combo boxes etc).
As such, For best Dark-Eclipse looks on Gtk, you should run Eclipse under a Dark theme like Adwaita-dark and use the ‘dark’ theme from Eclipse’s Appearance settings.

With the latest nightly build, you can make Eclipse look like this:
Eclipse dark looks

Hope it helps.

 

 

Appendix

1** I don’t have a good source that css is not applied recusivley. This is an observation from experimentation. As test, you can run any gtk app, open gtk inspector (Ctrl+shift+d) (if you have gtk3.14), then select a widget, on the 2nd set of tabs select ‘custom CSS’. From GtkComboBoxText you can’t theme the inner GtkToggleButton and GtkEntry from GtkComboBoxText. You can only theme them if you select the inner widgets directly. But the problem is that we don’t have access to those from SWT.
cannot_theme_gtkcomboboxtext_2015.04.07

If you spot an error in any of the text above, or have general feedback, please post a comment, it would be of much help.

[swt/gtk development] Why you should type the odd /*int*/ comment after long

You might have noticed that a lot of code in SWT/GTK has that odd /*int*/ comment after a long declaration.

long /*int*/ list 

I turns out the comment is needed for backwards 32 bit support.

So in general you should put it in parameter declarations and in variable declarations:

//Parameter declaration:
Control [] _getChildren (long /*int*/ parentHandle)

//Variable declaration:
long /*int*/ list = OS.gtk_container_get_children (parentHandle);

This is especially important in OS.java which is used to generate C code.

SWT Bug Triage

If you are a GTK/SWT developer and want to be involved in SWT Triage,
Then you should read:
https://www.eclipse.org/swt/triage.php

It is also useful to subscribe to the swt-platform email in bugzilla.
This way you’ll get emails for new SWT bugs and comment update on un-assigned bugs.
To do this, go to bugzilla, -> Preferences -> Email preferences
-> “Add users to my watch list” , add: platform-swt-inbox@eclipse.org
The only trouble is that you’ll get emails for all platforms (Windows/Mac/Linux) and you’ll have to create some filters for sorting things out. But in general I found that it’s good to be ‘aware’ of the issues that happen on windows/mac, as those sometimes occur on Linux also, or a bug labeled as ‘windows’ often impacts linux swt also.

 

 

Correct SWT code style for widget development and using Eclipse’s regex to fix your code style.

When doing SWT Development, if you submit code with the wrong style, you might get some code-comments from other contributors advising you to fix your style.

Luckily there is an Eclipse-SWT-formatted profile that one can use or one can fix them with some Regex.

Note: I will update this article as I find out more about SWT style.
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