Coding between Mouse and Keyboard, Part I

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This article shows you how to create the GUI of a tiny text editor without being a C++ guru. In Part II, we'll add missing functionality and translate the program into languages other than English.
Action!

In return, an editor needs some new actions to change the font characteristics. In the menu descending from the Action Editor's Create New Action icon (the little paper sheet on the left-hand side) we choose New Dropdown Action Group as a container for them and edit its properties. First, the action group is named “fontCharacter” in the name line of the Property Editor. Then we choose an appropriate icon using the “...” button next to the clicked iconSet property. Using the Add... button, it is possible to add icons stored somewhere in the filesystem.

Its text, automatically used for the menuText and the various tips (see Glossary), should read “Font Characteristics”. We change the tooltip and the statustip to “Choose font characteristics”, and most importantly, we set the exclusive property to False. This means that the user will be able to combine italics, bold and underlined font if needed. An exclusive action group would allow for only one of them at a time.

Glossary

With a right-click on the fontCharacter action group in the Action Editor and subsequent decision for New Action in the context menu, we add the italics action with Ctrl-I as accelerator key and Italics as text. Because the user can toggle italics on and off, it is important that the property toggleAction reads True. To begin with, italics should be off; therefore, the on property must have the value False.

We define the other two child actions of fontCharacter the same way, bold (Ctrl-B) and underline (Ctrl-U).

To add the entire fontCharacter action group to the toolbar, we simply drag it from the Action Editor to the form and drop it onto the toolbar. A right-click into the toolbar allows us to add a separator (Insert Separator).

By now, these actions don't do anything when playing with the preview available by pressing Ctrl-T. To let them actually do what they promise, we once again mark the italics action in the Action Editor, click on the red-blue Edit Connections icon and choose the toggled(bool) signal from the Signals list. Instead of connecting it to an ljeditor slot, we choose TextEdit in the Slots drop-down menu and subsequently setItalic(bool) in the list of slots provided by the QTextEdit class of which TextEdit is a member. No additional click is needed; with the appearance of the connection in the Connections: window, everything is done (see Figure 6), and the OK button is our friend.

Figure 6. When the italics action is toggled, ljedit writes italics or stops doing so.

Then we repeat the same procedure with the bold action's toggled(bool) signal and TextEdit's setBold(bool) slot. We connect the underline action to TextEdit's setUnderline(bool) slot. After this the preview reacts to Ctrl-I, Ctrl-B and Ctrl-U as wanted.

This encourages us to edit the connections of the predefined actions; these can't be toggled. Instead, they launch a user command like “save current data” when activated (i.e., clicked or chosen). That's why we connect the activated() signal to the appropriate slot.

For editRedoAction this is TextEdit::redo(). We disconnect the connection with the default ljeditor::editRedo(); it would be the right choice if we didn't want to rely on QTextEdit's redo() function. The same way, editUndoAction's activated() signal is connected with TextEdit::undo() and disconnected from the respective ljeditor function skeleton. We repeat this step with editPasteAction and the TextEdit::paste() slot editCopyAction and the TextEdit::copy() slot, and editCutAction and the TextEdit::cut() slot.

The remaining predefined actions (helpAboutAction, fileExitAction, fileSaveAction, fileSaveAsAction, fileOpenAction and fileNewAction) stay connected with the predefined ljeditor slot skeletons that we later have to fill with code.

One action is still missing: the one that the user activates to close the current editor window (as opposed to fileExitAction, which quits the entire application).

The work flow is a familiar one: we choose New Action from the Action Editor's Create new Action menu. The new action is named “fileCloseAction” in the Property Editor and is equipped with Close as text and Ctrl-Z as the keyboard accelerator.

However, we're missing a slot to connect its activated() signal. We fix this by opening the Slots... menu item in the Designer's Edit menu. Figure 7 shows the dialog that is opened now.

We add a slot with the function name fileClose(), the Return Type void and the Access type public. The Edit Slots dialog does no magic, it simply creates a function skeleton in the class definition of the ljeditor class.

Figure 7. A new function skeleton comes into being.

Now we can connect the fileCloseAction's activated() signal to ljeditor::fileClose() in the Edit Connections dialog provided by the Action Editor. As this action should be available via menu only, we simply drag and drop it into the File menu of the ljeditor form.

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