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Leave a comment Posted on May 9, 2018May 9, 2018 by leoufimtsev Fedora, Linux, Uncategorized

Gnome Wayland Screenshot tools (2018)

Most screenshot tools broke in Wayland. But luckily the developer community caught up quickly and we have a few functional alternatives.

Besides the native gnome-screenshot tool (which is a bit slow for heavy screenshotters) there are two other functional tools:

(Btw, I’m on Fedora 28, if you’re not, your milage may vary).

Fastest Tool:

If you’re looking for a 1-click thing without annotation, then Gnome-extension Screenshot Tool by oal is your friend.

Useful features include:

Configurable to be ‘one click on toolbar’ to make screenshot (Primary button option).
Auto copy to clipboard & autosave
Area/window/screen
Imgur & auto-upload support.
Keybindings

Installation:
1) (If not done so already) Install Gnome extension support for your browser.

2) (If not done so already) Also install the native connector (in addition to browser plugin).

On Fedora: dnf install chrome-gnome-shell

3) Install the extension:

https://extensions.gnome.org/extension/1112/screenshot-tool/

As a note, at time of writing, the area-selection seemed to include a blue overlay. Haven’t found a way around it so I use Flameshot for area screenshots.

Most Feature Rich : Flameshot

ScreenShot_2018-05-09_14:06:26.png

ScreenShot_2018-05-09_14:10:48.png

Features include:

Rich annotation tools. (Pencil, arrows, shapes, blurring)
Rich set of export tools (copy to clipboard, open in app, save, upload).
But missing ‘add text to screenshot’ at the moment (May 2018), which shutter had.

Installation:

sudo dnf install flameshot
See also github page

Double click on the status-bar icon & (wait for 2-3 seconds) to select area to screenshot.

Happy screenshotting!

Leave a comment Posted on April 23, 2018April 23, 2018 by leoufimtsev Uncategorized

LinkedList descendingIterator run time.

I couldn’t find the run time performance of LinkedList’s descendingIterator(), so I decided to roll up my sleves and investigate.

Theory 1: Linked list has to traverse to the end of the list to get the last node, so run time would be O(n).
Theory 2: Linked list keeps track of the last node and uses it. This would be O(1).

TL;DR; Getting Iterator has O(1) performance.

Reason:

Background: Descending iterator is useful if you want to iterate over a list backwards:


LinkedList myList = new LinkedList(); 
LinkedList myList = new LinkedList(); 
myList.add(1); 
myList.add(2); 
myList.add(3); 
Iterator myDescIter = myList.descendingIterator(); 
while (myDescIter.hasNext()) { 
   System.out.println(myDescIter.next()); 
}

I hunted around Java’s source code to investigate.
LinkedList has 2 internal references:

transient Node first;
transient Node last;

But it’s not actually referencing those until you call ‘iter.next()’.
When next() is called, it is redirected to previous();

private class DescendingIterator implements Iterator&lt;E&gt; {
 private final ListItr itr = new ListItr(size());
 public boolean hasNext() {
      return itr.hasPrevious();
 }

Which in turn returns the last node:

</pre>
public E previous() {
....
lastReturned = next = (next == null) ? last : next.prev;   // next == null -&gt; we get 'last'
<pre>

So in Theory 2 is correct, we start form the last node and thus get O(1).

As a side node, if you add a node after getting the iterator, and then use the iterator, you get an excepiton. So make sure to only get the iterator when you need it!

Leave a comment Posted on March 26, 2018 by leoufimtsev Eclipse, Fedora, Linux, Uncategorized

Eclipse + Flatpak Quick-start guide

Today I’m experimenting with the Eclipse to Flatpak port that our team has been working on.

To do so, I had to learn Flatpak. It only took 10 minutes to learn the basics needed to survive. I.e adding/listing Flapack repos, installing & removing packages.

Flatpack basics:

Flatpak is basically a package management system like yum/dnf/apk-get + version defined container for running gui apps.
Flatpak word does not contain a ‘c’. (I was wondering why flatpack could not be found on my system).
(Most?) of flatpak can be used via Software Center GUI, but I prefer the command line version as I need to manage repos.
The command line has very good tab-completion I’ve litereley figured things out by pressing tab when ever I wonder what argument to type next.
Flatpak is already installed on recent Fedora builds, but by default it has no repositories to feed from. You can add the flathub by opening it from here:
https://flatpak.org/setup/Fedora/
To verify that you’ve added the repo, you can list repos via:
```
flatpak remote-list
```
To list available packages:
```
flatpak remote-ls
```

To install these: (e.g I tested with Zotero)

flatpak install org.zotero.Zotero
flatpak install flathub org.zotero.Zotero  #if you want to specify which repo to install from

To remove a package:
```
flatpak uninstall org.zotero.Zotero
```

Eclipse in flatpak

Now I went a head and fidlded around with using Eclipse from Flatpak.
Eclipse comes in it’s own repository, as document by Mat Booth.
To set things up:

# Add the 'eclipse' repo. 
flatpak remote-add --if-not-exists eclipse https://fedorapeople.org/~mbooth/flatpak/eclipse.flatpakrepo

# Btw, if you want to delete a repo in the future, it's easy:
flatpak remote-delete eclipse     #again, tab completion is your friend.

# To see what's in Mat's eclipse repo, you can list it's content:
flatpak remote-ls eclipse
  org.eclipse.Committers   # I'm a committer, so I'm gonna go with this version.
  org.eclipse.Cpp 
  org.eclipse.Java 

flatpak install eclipse org.eclipse.Committers  #this asks if you want to install gnome 3.24 run time. Say yes.

Now you can run eclipse either via overviews or via command:

flatpak run org.eclipse.Committers

# or with environment variable:
YOUR_ENV_VAR=VALUE flatpak run org.eclipse.Committers

And voila, Eclipse is up and running:

Also useful:

# look for stuff in your flatpak
flatpak search vlc

# Update packages in the future:
flatpack update

# list what's installed
flatpak list
flatpak list --app #only list apps.

References:

2 Comments Posted on October 6, 2016October 6, 2016 by leoufimtsev Eclipse, Fedora, Uncategorized

Make applications (Eclipse) use x11 backend on Wayland (Fedora 25)

I upgraded to Fedora 25 (beta), which by default uses the new Wayland display server, (which is a replacement for x11).

Continue reading →

6 Comments Posted on September 19, 2016September 19, 2016 by leoufimtsev Eclipse, Programming, Uncategorized

Eclipse basics for Java development

Just a basic into to Eclipse, aimed at people who are new to Java. Covers creating a new project, debugging, common shortcuts/navigation, git.

Continue reading →

1 Comment Posted on September 6, 2016September 8, 2016 by leoufimtsev Cross-Platform, Fedora, Linux, swt, Uncategorized

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:

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

3 Comments Posted on September 2, 2016September 2, 2016 by leoufimtsev Bash Scripts, Linux, Uncategorized

Ramdisk for the impatient.

I have a pci-e based storage working at close to 1000mb/s (Mac Pro). I do lots of GCC/make compilations. What if you want things even faster than with a pcie? Then ramdisk is your friend.

My results:

With Regular SSD: 2 minutes and 37 seconds (on my co-worker’s machine w/Fedora)
With my pci-e disk: 2 minutes and 35 seconds (my Mac w/Fedora)
With Ramdisk: 1 minute and 15 seconds (my Mac w/Fedora)

So we have ~50% improvement in compilation time. For me, it’s worth the effort.

To set one up: Follow this guide

I.e:

[code language='bash']
sudo mkdir /mnt/ramdisk
sudo mount -t tmpfs -o size=2G tmpfs /mnt/ramdisk
[/code]

To see how much of it is still available:

df -h

You might want to write an rsync script to copy folders onto the ramdisk that you want fast-access to. Ex a git repo that you compile frequently, some application binaries that you run. But obviously avoid putting data onto the disk.

Leave a comment Posted on September 29, 2014October 27, 2014 by leoufimtsev Eclipse, gtk, Linux, Programming, swt, Uncategorized

How to compile various gtk3 versions and run eclipse Apps with those (for SWT Widget testing)

When developing SWT widgets, we need to test them on various GTK versions to ensure backwards compatibility.

There are some tricks and perks involved.

Get Gtk sources

Go to the gtk git repo and pull the code: https://git.gnome.org/browse/gtk+/
(I recommend the https version: https://git.gnome.org/browse/gtk+)
(if you don’t know how to use eclipse’s EGit, read this)
Check out the versions that you’re interested in (e.g 2.24, 3.10, 3.4, 3.8)
These are found in major Linux distributions (e.g ubuntu 12..).
For the time being, check out the newest gtk version (e.g 3.10 at the time of writing).
(It’s easier to build a newer version than an older one)

Open Terminal, go to your checked out gtk branch.
Run the following commands:

./autogen.sh
./configure --enable-x11-backend --enable-wayland-backend
make

The first time you run the commands, you might run into errors telling you you’re missing something on your system. Inspect autogen.sh to see what it runs and then install the utilities with yum.
Now copy gtk to another place on your system. E.g ~/src/gtk2_24 This way you don’t have to recompile this business every time.
Now you can build the other versions and similarly copy them to ~/src/gtk*_*
NOTE ON gtk3.4 (and maybe older) The Wayland configuration makes certain things look more correct. But sometimes it makes building older versions (like gtk3.4) near impossible due to missing dependencies. In this case, run the configure without these:
```
 ./autogen.sh ./configure make 
```

Configure Eclipse to use the gtk you compiled

Edit your run-configuration of the code snippet that you want to run.
Navigate to “Environmental Variables”
Click on “Add”, type in:
name: LD_LIBRARY_PATH
path: #your_compiled_gtk //e.g /home/lufimtse/src/gtk3_10/gtk/.libs
Name your configuration (I reccomend appending gtk version, e.g “ControlExample (g3-10)”)
It should look something like this:
Now run the configuration and you should see your application rendered in gtk*.*.
You may note that it won’t have any styling:
The lack of styling is due to the fact that there is no theaming.
Now sometimes you might want the compiled gtk to use your system theame to see impact of themes on looks.
To do so, do as above except run the configuration as following:
```
./configure --prefix=/usr --sysconfdir=/etc --enable-broadway-backend --enable-x11-backend --disable-wayland-backend
```
In the interest of comparison: (left native look, right bare look)
Lastly, in your source code, you might want to verify that you’re running the compiled gtk and not your own. Use this line of code:
```
System.out.println("GTK Version: " + OS.gtk_major_version() + "." + OS.gtk_minor_version() + "." + OS.gtk_micro_version());
```

Coffee Oriented Programming