Rocket Builder

A package for educational use. It is mainly for creating a Gtk3 GUI for manipulating objects created in the Rockets package.

GTK Resources

While developing a GTK application, these are useful resources

• Widget - Visual overview over GTK3 widgets.
• GtkBuilder - Used to load .glade UI design files.

Data

Under the data directory we have rockets.sql which contains SQL statements needed to create the rockets.db SQLite3 database.

Source Code

The rocketbuilder.jl file is meant as a way of easily launching the application. It needs some more work to function properly.

Under the src directory you find these files of significance:

• db.jl - Code interfacing with SQLite3 database found in data/rockets.db
• tank-editor.jl - Shows a GUI for adding and removing data for propellant tanks to the database.

Usable Observations From Development

Not all SQL statements support placeholdres such as ?. For instance this is possible:

query = DBInterface.prepare(db, "INSERT INTO Tanks VALUES(?, ?, ?)")
DBInterface.execute(query, [name, tank.total_mass, tank.dry_mass])

However using a placeholder for the SELECT statement doesn't seem to work.

When working with Gtk3 keep in mind that you are working with a C library with a minimal wrapper. For instance there has been no attempt to wrap the setting of all properties with a Julia function. Gtk objects are GObjects which have properties which can be looked up and set at runtime. In julia we do it like this:

set_gtk_property!(win, :title, "New title")

This applies to windows, buttons, layout or pretty much anything. You can get a property like this:

get_gtk_property(win, :title, String)

Notice how you got to write that you want a String back. Don't get clever about this. It is not smart enough to convert a string to a number. So when getting the content of a textfield you need to convert to a number explicitly.

drytxt = get_gtk_property(dryentry, :text, String)
totaltxt = get_gtk_property(totalnetry, :text, String)

dry = parse(Float64, drytxt)
total = parse(Float64, totaltxt

Remember when done with the database to close it:

db = opendb()

# Do a bunch of stuff

DBInterface.close!(db)

Tree View

One of the more complex controls in Gtk is the tree view so lets have some remarks on how to use it.

model = GtkTreeModel(list)
tree = GtkTreeView(model)

You got different ways of rendering a cell in the tree view. You need one of these if you are showing text.

txtcell = GtkCellRendererText()

The tree view can have multiple columns. Here we are defining only a single column with the header Tank. The list store provided to the model can have many columns. Dict([("text", 0)]) says we are using a txtcell renderer for the value in the first column in the list store.

col1 = GtkTreeViewColumn("Tank", txtcell, Dict([("text",0)]))
push!(tree, col1)