CS108 Lecture 28: Graphical User Interface: Using PythonCard - - PDF document

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Aaron Stevens

8 April 2009

CS108 Lecture 28: Graphical User Interface: Using PythonCard Dialogs

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Overview/Questions

– How do we start developing GUI applications? – Programming with events: Some useful starter code. – Using the PythonCard Code Editor. – Using pre-made dialogs to create snazzy looking GUI applications with very little new code.

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PythonCard GUI: Getting Started

We will have 2 files for any PythonCard GUI application we create:

– <filename>.py : the application code – <filename>.rsrc.py : the resource file, which defines the layout of the GUI widgets and their properties.

We will begin our GUI programming by using some starter code which creates a basic window.

– starter01.py : the application code – starter01.rsrc.py : the resource file

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GUI Applications: Getting Started

The starter code creates this basic window: which has a single button on it. We’ll come back to how to design such a window next time.

• Notice the window takes on the “native” look and feel

for either Windows or Mac, as needed.

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GUI Applications: Getting Started

The starter code has a simple class definition as well, which we will modify:

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GUI Applications: Getting Started

Notice the following things about this starter code:

– Class Minimal inherits from model.Background – Some event handler methods have been defined.

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PythonCard Code Editor

PythonCard GUI applications do not seem to run nicely in IDLE on Windows.

– Seems to work fine on Mac OSX. – Works for me on Windows on my Mac.

The PythonCard distribution comes with its

• wn tool, called Code Editor.

– Look for it:

• Start / Programs / PythonCard / Code Editor

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Using an Event Handler

We can test out these event handlers by writing some code in the methods, and seeing when it executes. For example:

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Dialogs

Dialogs are windows which are used for specific user-interactions. Several common dialogs appear in many programs:

– Message box – Text entry – Scrollable text output – Single/multiple choice (select from a list) – Pick a color – Open a file

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Dialogs

Dialogs are windows which are used for specific user-interactions. Several common dialogs appear in many programs:

– Message box – Text entry – Scrollable text output – Single/multiple choice (select from a list) – Pick a color – Open a file

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Modality

Modality refers to a dialog (window) being

• ptional or required.

– A modal window must be “dismissed” by the user before returning to the “parent” window. – A non-modal window can be ignored.

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Message Dialog

The Message Dialog produces this kind of window: It is invoked using this general form:

result = dialog.messageDialog(self, <message>, <title>)

Print out return value to see its elements. Note optional parameters for icon, buttons.

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Text Entry Dialog

The Text Entry dialog produces this kind of window: It is invoked using this general form:

result = dialog.textEntryDialog(self, <message>, <title>, <defaultText>)

Print out return value to see its elements.

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Single Choice Dialog

The Single Choice Dialog produces this kind of window: It is invoked using this general form:

result = dialog.singleChoiceDialog(self, <message>, <title>,<list>)

Print out return value to see its elements. Note optional parameters for icon, buttons.

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Scrolled Message Dialog

The Scrolled Message Dialog produces this kind

• f window:

It is invoked using this general form:

result = dialog.scrolledMessageDialog(self, <message>, <title>)

Print out return value to see its elements.

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File Dialog

The File Dialog produces this kind of window: It is invoked using this general form:

result = dialog.fileDialog(self, <message>, <path>, <filename>, <wildcard>)

Note: this dialog will accept several blank values:

result = dialog.fileDialog(self, <message>,’’,’’,’’)

Print out return value to see its elements.

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About the Dialogs’ Return Values

Each provides data back to the programmer using an

• bject of type DialogResults, which provides data

members to read user responses. – The API page lists the specific return parameters, which are data members of the result object.* Example (for Single Choice Dialog): print result.selection

*Note: the API page is wrong when it says that the return value is a dict object. It should read: "The <whatever>Dialog component returns a wxPython DialogResults object which contains <number> values, as shown in the following table."

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From Dialogs to Applications

We can apply the input, process, output design pattern for GUI applications using dialogs:

– Present a dialog to the user, and collect some input. – Use that input in processing. – Present the output in another GUI dialog.

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Take-Away Points

– PythonCard files: .rsrc.py, .py – PythonCard Code Editor – Using the PythonCard pre-packaged dialogs

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Student To Dos

– Readings:

The PythonCard Dialogs: (today)

http://pythoncard.sourceforge.net/dialogs/index.html

The PythonCard Resource editor (next week)

http://pythoncard.sourceforge.net/resource_editor_overview.html

– Install wxPython and PythonCard

** only needed if you want to do hws on your own computer

– Aaron’s Office Hours changed this week only:

• Friday: Cancelled

– NO LECTURE on FRIDAY 4/10 – HW12 is due TUESDAY 4/14