"Simple" Stage 4
The program has now progressed and the GUI begins to look like GUIs usually look. Visually, the most noticeable change is the presence of several icons on the tool bar - basically, these icons have the same functionality as the menu items and are provided for the most frequently used operations. So we will need to talk some more about the actions and about generation and storage of resources. Once you download the program listing and start using it, other changes will be noticed: at the end of the mouse pointer, a tool tip hint pops up showing the purpose of the icon that the pointer is hovering over. Also, an informative note, often the same as the tool tip hint, is shown on the status bar.
In connection with the above, we will need to discuss how icon images are provided for icons.
One item that I missed in earlier versions is showing of the title of document opened in the edit window. The title is functional and it shows when the document has been altered. Not only that, there is a program bug that PyQt (or Qt) reports. I found the chasing after this bug as frustrating as it was instructive. It was not easy to find, yet I think that a programmer with experience in PyQt would spot it in no time at all! See if you can spot it easily.
Simple0.0.06.png
Below is the code listing for this stage of development. It is very often difficult to copy the code from a wiki. This is particularly so with Python programs, because Python relies on indentation for specification of code blocks (and it is such a nice feature, once you get used to it!). To make it simpler to test this stage of program, we provide a tar ball of program for downloading: see http://akabaila.pcug.org.au/data_sample and select the tar ball named simple0.0.06.tar.gz.
1 #!/usr/bin/env python
2 # .../simple.py - developing of a simple text editor.
3 '''A really simple editor program in PyQt4 - simple.py
4 '''
5
6 import sys
7 import os
8
9 from PyQt4.QtGui import (QMainWindow, QApplication, QFileDialog,
10 QKeySequence, QAction, QIcon)
11 from PyQt4.QtCore import SIGNAL
12
13 from ui_simple import Ui_MainWindow
14 import qrc_simple
15
16 __version__ = "0.0.06"
17
18 class MainWindow(QMainWindow, Ui_MainWindow):
19 def __init__(self, parent=None):
20 super(MainWindow, self).__init__(parent)
21 self.setupUi(self)
22 self.action_New = self.editAction(self.action_New, self.fileNew,
23 QKeySequence.New, "filenew",
24 'Clear the textEdit window for a new file.')
25 self.action_Open = self.editAction(self.action_Open, self.fileOpen,
26 QKeySequence.Open, "fileopen", "Open an existing file")
27 self.action_Save = self.editAction(self.action_Save, self.fileSave,
28 QKeySequence.Save, "filesave", "Save file")
29 self.actionSave_As = self.editAction(self.actionSave_As, self.fileSaveAs,
30 "Ctrl+A", "filesaveas", "Save file with a new name")
31 self.fileName = None
32 #-------------------------------------------------------------------------------------
33 fileToolbar = self.addToolBar("File")
34 self.addActions(fileToolbar, (self.action_New, self.action_Open,
35 self.action_Save, self.actionSave_As))
36 #--------------------------------------------------------------------------------------
37 self.resize(600, 400)
38 self.dirty = False
39 self.textEdit.textChanged.connect(self.setDirty)
40 #--------------------------------------------------------------------------------------
41 def setDirty(self):
42 '''On change of text in textEdit window, set the flag
43 "dirty" to True'''
44 if self.dirty:
45 return True
46 self.dirty = True
47 self.updateStatus('self.dirty set to True')
48
49 def clearDirty(self):
50 '''Clear the dirty flag and update status'''
51 self.dirty = False
52
53 def updateStatus(self, message):
54 if self.fileName is not None:
55 flbase = os.path.basename(self.fileName)
56 self.setWindowTitle(unicode("Simple Editor - " + flbase + "[*]") )
57 self.statusBar().showMessage(message, 3000)
58 self.setWindowModified(self.dirty)
59
60 def okToContinue(self):
61 if self.dirty:
62 reply = QMessageBox.question(self,
63 "Simple Editor - Unsaved Changes",
64 "Save unsaved changes?",
65 QMessageBox.Yes|QMessageBox.No|QMessageBox.Cancel)
66 if reply == QMessageBox.Cancel:
67 return False
68 elif reply == QMessageBox.Yes:
69 return self.fileSave()
70 return True
71
72 def addActions(self, target, actions):
73 for action in actions:
74 if action is None:
75 target.addSeparator()
76 else:
77 target.addAction(action)
78
79 def editAction(self, action, slot=None, shortcut=None, icon=None,
80 tip=None, checkable=False, signal="triggered()"):
81 if icon is not None:
82 action.setIcon(QIcon(":/{0}.png".format(icon)))
83 if shortcut is not None:
84 action.setShortcut(shortcut)
85 if tip is not None:
86 action.setToolTip(tip)
87 action.setStatusTip(tip)
88 if slot is not None:
89 # self.connect(action, SIGNAL(signal), slot)
90 action.triggered.connect(slot)
91 if checkable:
92 action.setCheckable(True)
93 return action
94
95 def fileNew(self):
96 '''Clear the editor window for a new file with name
97 specified in fileSaveAs method.'''
98 self.textEdit.setText('')
99 self.statusBar().showMessage('File menu: New selected', 8000)
100
101 def fileOpen(self):
102 '''Open file'''
103 fname = unicode(QFileDialog.getOpenFileName(self,
104 "Open File", '.', "Files (*.*)"))
105 if not (fname == ""):
106 self.textEdit.setText(open(fname).read())
107 self.fileName = fname
108 else:
109 return
110 self.clearDirty()
111 self.updateStatus('File opened.')
112
113 def fileSave(self):
114 if self.fileName is None:
115 return self.fileSaveAs()
116 else:
117 fname = self.fileName
118 fl = open(fname, 'w')
119 tempText = self.textEdit.toPlainText()
120 if tempText:
121 fl.write(tempText)
122 fl.close()
123 self.clearDirty()
124 self.updateStatus('Saved file')
125 return True
126 else:
127 self.statusBar().showMessage('Failed to save ...', 5000)
128 return False
129
130 def fileSaveAs(self):
131 path = self.fileName if self.fileName is not None else "."
132 fname = unicode(QFileDialog.getSaveFileName(self,
133 "Simple Editor, SaveAs ", path, "Any File (*.*)"))
134 if fname:
135 if "." not in fname:
136 fname += ".txt"
137 self.fileName = fname
138 self.fileSave()
139 self.statusBar().showMessage('SaveAs file' + fname, 8000)
140 self.clearDirty()
141
142 if __name__ == '__main__':
143 app = QApplication(sys.argv)
144 frame = MainWindow()
145 frame.show()
146 app.exec_()
The listing is more extensive - the number of lines has about doubled from the previous section. On the other hand, the simple editor now looks like a "real" program and is able to do what we expect of a simple, tutorial type, plain text editor!