My first GTK application

Page updated: April 16, 2011
I have got to say, this has been an incredible experience. I sat in front of my computer almost the entire day (Nov. 15, 2010), writing my first serious application in BaCon.
What I must emphasize here is that I had only messed around very casually a couple of days beforehand, looking around in the BaCon documentation and examples.
Early in the morning (Nov. 15) I was discussing on my blog the need for a GUI to setup handling of a proxy server for Internet access in Puppy ....then I thought, well, this will be a very good exercise to learn BaCon coding at the same time.

Come evening, it is done, and I am already an accomplished BaCon programmer. Most extraordinary is the ease with which I developed the GUI window and the interface with my code. I used HUG (Highlevel Universal GUI) which, it turns out, is a delight to use.

For you to have the same pleasant experience, I recommend having the online documentation open (with popup keyword menu):

http://www.basic-converter.org/documentation.html

Oh yeah, the HUG documentation is an essential read:

http://www.basic-converter.org/hugdoc.html

You do need to have a recent Puppy Linux with support for BaCon. Well, any Unix/Linux/MacOSX with BaCon installed (and preferably the 'bacon' compiler compiled) and a text editor that supports syntax highlighting for BaCon. The Puppy BaCon PET package has 'hug.bac', the HUG source file, at /usr/share/BaCon -- this may differ for another distro. Then off you go...

My first window

The very first thing that I did was create a little empty window. Here is the complete program:

REM setup proxy server for wget
REM Barry Kauler, my first BaCon GTK program

INCLUDE "/usr/share/BaCon/hug.bac"
INIT

mainwin = WINDOW("Proxy server setup", 400, 300)

REM endless gtk loop...
DISPLAY

Well, no need for a snapshot, it is just an empty window. Here is the code if you want to try it for yourself: proxy_setup1.bac. To compile is easy:

# bacon proxy_setup1.bac

Widgets and more widgets

Then I populated it with the various widgets that I wanted:

REM setup proxy server for wget
REM Barry Kauler, my first BaCon GTK program

INCLUDE "/usr/share/BaCon/hug.bac"
INIT

mainwin = WINDOW("Proxy server setup", 400, 285)

image1=IMAGE("/usr/local/lib/X11/pixmaps/www48.png",48,48)
ATTACH(mainwin,image1,10,10)

label_hdr1=MARK("If you connect to the Internet through a proxy",350,15)
ATTACH(mainwin,label_hdr1,58,10)
label_hdr2=MARK("server, tick the checkbox and fill in the fields",350,15)
ATTACH(mainwin,label_hdr2,58,25)
label_hdr3=MARK("(leave Username/Password blank if not needed)",350,15)
ATTACH(mainwin,label_hdr3,58,40)

check1 = CHECK("Enable Internet connection through proxy server",350,20)
ATTACH(mainwin,check1,20,70)

label_http = MARK("HTTP:",50,20)
ATTACH(mainwin, label_http, 10, 100)
httpproxy = ENTRY("foo.org:8080",280,20)
ATTACH(mainwin, httpproxy, 100, 100)

label_ftp = MARK("FTP:",50,20)
ATTACH(mainwin, label_ftp, 10, 130)
ftpproxy = ENTRY("foo.org:8080",280,20)
ATTACH(mainwin, ftpproxy, 100, 130)

label_user=MARK("Username:",80,20)
ATTACH(mainwin,label_user,10,160)
username = ENTRY("",280,20)
ATTACH(mainwin, username, 100, 160)

label_pass=MARK("Password:",80,20)
ATTACH(mainwin,label_pass,10,190)
password1=PASSWORD(150,20)
ATTACH(mainwin,password1,100,190)

label_pass=MARK("Enter password again:",170,20)
ATTACH(mainwin,label_pass,10,220)
password1=PASSWORD(150,20)
ATTACH(mainwin,password1,180,220)

ok_btn = BUTTON("OKAY", 65, 25)
ATTACH(mainwin, ok_btn, 240, 250)
cancel_btn = BUTTON("Cancel", 65, 25)
ATTACH(mainwin, cancel_btn, 320, 250)

REM Define the callbacks
CALLBACK(ok_btn, QUIT)
CALLBACK(cancel_btn, QUIT)

REM endless gtk loop...
DISPLAY

That is highly readable, and as a raw beginner I had no hesitation at all creating it. Here is the file: proxy-setup2.bac

Callbacks

Then I got stuck into the backend code to make it do something useful. This mainly involves defining callbacks, that respond to actions in the GUI window, and vice-versa, values that can be posted from the code to the window.

Here are my first steps:

REM setup proxy server for wget
REM Barry Kauler, my first BaCon GTK program using HUG

INCLUDE "/usr/share/BaCon/hug.bac"
INIT

http_proxy$=GETENVIRON$("http_proxy")
ftp_proxy$=GETENVIRON$("ftp_proxy")

proxy_flag=0
IF http_proxy$ != "" THEN proxy_flag=1
IF ftp_proxy$ != "" THEN proxy_flag=1

SUB check1_callback
 LOCAL status
 status=GET(check1)
 IF status = 1 THEN
  ENABLE(httpproxy)
  ENABLE(ftpproxy)
  ENABLE(username)
  ENABLE(password1)
  ENABLE(password2)
 ELSE
  DISABLE(httpproxy)
  DISABLE(ftpproxy)
  DISABLE(username)
  DISABLE(password1)
  DISABLE(password2)
 ENDIF
ENDSUB

mainwin = WINDOW("Proxy server setup", 400, 285)

image1=IMAGE("/usr/local/lib/X11/pixmaps/www48.png",48,48)
ATTACH(mainwin,image1,10,10)

label_hdr1=MARK("If you connect to the Internet through a proxy",350,15)
ATTACH(mainwin,label_hdr1,58,10)
label_hdr2=MARK("server, tick the checkbox and fill in the fields",350,15)
ATTACH(mainwin,label_hdr2,58,25)
label_hdr3=MARK("(leave Username/Password blank if not needed)",350,15)
ATTACH(mainwin,label_hdr3,58,40)

check1 = CHECK("Enable Internet connection through proxy server",350,20)
ATTACH(mainwin,check1,20,70)

label_http = MARK("HTTP:",50,20)
ATTACH(mainwin, label_http, 10, 100)
httpproxy = ENTRY("foo.org:8080",280,20)
ATTACH(mainwin, httpproxy, 100, 100)

label_ftp = MARK("FTP:",50,20)
ATTACH(mainwin, label_ftp, 10, 130)
ftpproxy = ENTRY("foo.org:8080",280,20)
ATTACH(mainwin, ftpproxy, 100, 130)

label_user=MARK("Username:",80,20)
ATTACH(mainwin,label_user,10,160)
username = ENTRY("",280,20)
ATTACH(mainwin, username, 100, 160)

label_pass=MARK("Password:",80,20)
ATTACH(mainwin,label_pass,10,190)
password1=PASSWORD(150,20)
ATTACH(mainwin,password1,100,190)

label_pass=MARK("Enter password again:",170,20)
ATTACH(mainwin,label_pass,10,220)
password2=PASSWORD(150,20)
ATTACH(mainwin,password2,180,220)

ok_btn = BUTTON("OKAY", 65, 25)
ATTACH(mainwin, ok_btn, 240, 250)
cancel_btn = BUTTON("Cancel", 65, 25)
ATTACH(mainwin, cancel_btn, 320, 250)

REM Define the callbacks
CALLBACK(ok_btn, QUIT)
CALLBACK(cancel_btn, QUIT)
CALLBACK(check1,check1_callback)

REM tick or untick the checkbox...
SET(check1,1)
SET(check1,proxy_flag)

REM endless gtk loop...
DISPLAY

The code is here: proxy-setup3.bac

The complete application

Well, it was really just more of the same. I got stuck into the logical steps required to manage the proxy settings.

Then there it was, a working program:
window

Here is the source code: proxy-setup.bac

Or, as a HTML page: proxy-setup.bac.html

...well, although this was my first BaCon GTK application, I did revisit this code and tidy it up a bit and add some extra stuff such as international language support, improved layout and shared hug.so, see notes below.

I compiled it like this:

# bacon -x proxy-setup.bac

The -x option is for international language support, see my Internationalization page.

I also put some code in to ensure that layout always renders properly, such as no truncated text, for all theme/font settings and screen resolution/dpi settings -- see my layout page.

Note that recent puppies have /usr/lib/hug.so, which is hug.bac compiled as a shared library. This reduces the size of individual applications. The code replaces this:

INCLUDE "/usr/share/BaCon/hug.bac"

With this, to use the shared hug.so library:

INCLUDE "/usr/share/BaCon/hug_imports.bac"

The stripped executable is 50KB, not too bad (with hug.bac included it is about 90KB). The source file is 7.2KB. Note, this application is now in Puppy, in /usr/local/simple_network_setup.

My BaCon intro page:

http://bkhome.org/bacon/