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Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	1	<HTML><HEAD><TITLE>Using python to create Macintosh applications, part two</TITLE></HEAD>
				2	<BODY>
				3	<H1>Using python to create Macintosh applications, part two</H1>
				4	<HR>
				5
				6	In this document we rewrite the application of the <A
				7	HREF="example1.html">previous example</A> to use modeless dialogs. We
				8	will use an application framework, and we will have a look at creating
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	9	applets, standalone applications written in Python. The <A
				10	HREF="example2/dnslookup-2.py">source code</A> and
				11	<A HREF="example2/dnslookup-2.rsrc">resource file</A> are available in the folder
				12	<A HREF="example2">example2</A>. <p>
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	13
				14	Again, we start with ResEdit to create our dialogs. Not only do we
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	15	want a main dialog this time but also an "About" dialog. This example is less
				16	than complete since we do not provide a <A NAME="bundle">BNDL resource</A>
				17	and related stuff that an application cannot be without. We are able to do this
				18	when building a python applet since BuildApplet will substitute default resources
				19	for BNDL, etc. when none are supplied (<A HREF="#no-bundle">See below</A>.)
				20	"Inside Mac" or various
				21	books on Macintosh programming will help here. Also, you can refer to
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	22	the resource files provided in the Python source distribution for some
				23	of the python-specific points of BNDL programming: the
				24	"appletbundle.rsrc" file is what is used for creating applets if you
				25	don't provide your own resource file. <p>
				26
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	27	When creating your own BNDL resouorces, keep in mind that the Finder gets
				28	confused if you have more than one application with the same signature. This may be due
				29	to some incorrectness on the side of "BuildApplet", I am not sure. There is one
				30	case when you definitely need a unique signature: when you create an applet that
				31	has its own data files and you want the user to be able to start your
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	32	applet by double-clicking one of the datafiles. <p>
				33
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	34	Let's have a look at dnslookup-2.rsrc, our resource file. Dialog 512 is the
				35	main window which has one button (Lookup), two labels and
Jack Jansen	dd20689	1999-12-03 16:00:20 +0000	[diff] [blame]	36	two text entry areas, one of which is used for output only. The "Quit"
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	37	button has disappeared, because its function is handled by a menu choice. Here's
				38	what it will look like at run time:<p>
				39	<div align=center>
				40	<img width=324 height=205 src="example2/dnslookup-2.gif" alt="dialog image">
				41	</div>
				42	<p>
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	43
				44	<H2>A modeless dialog application using FrameWork</H2>
				45
				46	On to the source code in <A
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	47	HREF="example2/dnslookup-2.py">dnslookup-2.py</A>. The
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	48	start is similar to our previous example program <A
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	49	HREF="example1/dnslookup-1.py">dnslookup-1.py</A>, with
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	50	one extra module being imported. To make life more simple we will use
				51	the <CODE>FrameWork</CODE> module, a nifty piece of code that handles
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	52	all the gory Mac details of event loop programming, menubar
				53	installation and all the other code that is the same for every Mac
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	54	program in the world. Like most standard modules, FrameWork will run
				55	some sample test code when you invoke it as a main program, so try it
				56	now. It will create a menu bar with an Apple menu with the about box
				57	and a "File" menu with some pythonesque choices (which do nothing
				58	interesting, by the way) and a "Quit" command that works. <p>
				59
Jack Jansen	0836542	1996-04-19 15:56:08 +0000	[diff] [blame]	60	<BLOCKQUOTE>
				61	If you have not used <code>FrameWork</code> before you may want to
				62	first take a look at the <A HREF="textedit.html">Pathetic EDitor</A>
				63	example, which builds a minimal text editor using FrameWork and TextEdit.
				64	On the other hand: we don't use many features of FrameWork, so you could
				65	also continue with this document.
				66	</BLOCKQUOTE>
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	67
				68	After the imports we get the definitions of resource-IDs in our
				69	resource file, slightly changed from the previous version of our
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	70	program. The main program is also
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	71	similar to our previous version, with one important exception: we
				72	first check to see whether our resource is available before opening
				73	the resource file. Why is this? Because later, when we will have
				74	converted the script to an applet, our resources will be available in
				75	the applet file and we don't need the separate resource file
				76	anymore. <p>
				77
				78	Next comes the definition of our main class,
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	79	<CODE>DNSLookup</CODE>, which inherits
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	80	<CODE>FrameWork.Application</CODE>. The Application class handles the
				81	menu bar and the main event loop and event dispatching. In the
				82	<CODE>__init__</CODE> routine we first let the base class initialize
				83	itself, then we create our modeless dialog and finally we jump into
Jack Jansen	ef5cd05	1996-09-17 12:39:12 +0000	[diff] [blame]	84	the main loop. The main loop continues until we call <CODE>self._quit</CODE>,
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	85	which we will do when the user selects "Quit". When we create
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	86	the instance of <CODE>MyDialog</CODE> (which inherits
				87	<CODE>DialogWindow</CODE>, which inherits <CODE>Window</CODE>) we pass
				88	a reference to the application object, this reference is used to tell
				89	Application about our new window. This enables the event loop to keep
				90	track of all windows and dispatch things like update events and mouse
				91	clicks. <p>
				92
				93	The <CODE>makeusermenus()</CODE> method (which is called sometime
				94	during the Application <CODE>__init__</CODE> routine) creates a File
				95	menu with a Quit command (shortcut command-Q), which will callback to
Jack Jansen	ef5cd05	1996-09-17 12:39:12 +0000	[diff] [blame]	96	our quit() method. <CODE>Quit()</CODE>, in turn, calls <CODE>_quit</CODE> which
				97	causes the mainloop to terminate at a convenient time. <p>
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	98
				99	Application provides a standard about box, but we override this by
				100	providing our own <CODE>do_about()</CODE> method which shows an about
				101	box from a resource as a modal dialog. This piece of code should look
				102	familiar to you from the previous example program. That do_about is
				103	called when the user selects About from the Apple menu is, again,
				104	taken care of by the __init__ routine of Application. <p>
				105
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	106	The <CODE>MyDialog</CODE> class is the container for our main
				107	window. Initialization is again done by first calling the base class
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	108	<CODE>__init__</CODE> function and finally setting the local variable
				109	"parent." <p>
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	110
				111	<CODE>Do_itemhit()</CODE> is called when an item is selected in this
				112	dialog by the user. We are passed the item number (and the original
				113	event structure, which we normally ignore). The code is similar to the
				114	main loop of our previous example program: a switch depending on the
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	115	item selected. <CODE>Dnslookup()</CODE> is quite similar to our previous
				116	example. <p>
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	117
				118	<H2><IMG SRC="html.icons/mkapplet.gif"><A NAME="applets">Creating applets</A></H2>
				119
Jack Jansen	3412c5d	1997-08-27 14:08:22 +0000	[diff] [blame]	120	Now let us try to turn the python script into an applet, a standalone
				121	application. This will <em>not</em> work if you have the "classic 68k"
Jack Jansen	a2139fe	1998-02-25 15:40:35 +0000	[diff] [blame]	122	Python distribution, only if you have the cfm68k or PPC distribution.
				123
				124	<blockquote>
Jack Jansen	3412c5d	1997-08-27 14:08:22 +0000	[diff] [blame]	125	Actually, "standalone" is probably not the correct term here, since an
				126	applet does still depend on a lot of the python environment: the
				127	PythonCore shared library, the Python Preferences file, the python Lib
				128	folder and any other modules that the main module depends on. It is
Jack Jansen	a2139fe	1998-02-25 15:40:35 +0000	[diff] [blame]	129	possible to get rid of all these dependencies and create true standalone
Jack Jansen	dd20689	1999-12-03 16:00:20 +0000	[diff] [blame]	130	applications in Python, but this is a bit difficult. See <a href="freezing.html">
Jack Jansen	a2139fe	1998-02-25 15:40:35 +0000	[diff] [blame]	131	Standalone Applications in Python</a> for details. For this
				132	document, by standalone we mean here that
Jack Jansen	3412c5d	1997-08-27 14:08:22 +0000	[diff] [blame]	133	the script has the look-and-feel of an application, including the
Jack Jansen	a2139fe	1998-02-25 15:40:35 +0000	[diff] [blame]	134	ability to have its own document types, be droppable, etc.
				135	</blockquote>
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	136
				137	The easiest way to create an applet is to take your source file and
Jack Jansen	3412c5d	1997-08-27 14:08:22 +0000	[diff] [blame]	138	drop it onto "BuildApplet", located in the Python home
				139	folder. This will create an applet with the same name as your python
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	140	source with the ".py" stripped. Also, if a resource file with the same
				141	name as your source but with ".rsrc" extension is available the
				142	resources from that file will be copied to your applet too. If there
				143	is no resource file for your script a set of default resources will be
Jack Jansen	3412c5d	1997-08-27 14:08:22 +0000	[diff] [blame]	144	used, and the applet will have the default creator 'Pyt0'. The latter
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	145	also happens if you do have a resource file but without the BNDL
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	146	combo. <A NAME="no-bundle">Actually</A>, as in the present example.
				147	<p>
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	148
Jack Jansen	3412c5d	1997-08-27 14:08:22 +0000	[diff] [blame]	149	If you need slightly more control over the BuildApplet process you can
				150	double-click it, and you will get dialogs for source and
Jack Jansen	a630813	1996-03-18 13:38:52 +0000	[diff] [blame]	151	destination of the applet. The rest of the process, including locating
				152	the resource file, remains the same. <p>
				153
				154	Note that though our example application completely bypasses the
				155	normal python user interface this is by no means necessary. Any python
				156	script can be turned into an applet, and all the usual features of the
				157	interpreter still work. <p>
				158
				159	That's all for this example, you may now return to the <A HREF="index.html">
				160	table of contents</A> to pick another topic. <p>
Jack Jansen	2450a25	1999-12-03 15:15:28 +0000	[diff] [blame]	161	</BODY>
				162	</HTML>