PolygonView: A Non-Opaque NSView
In this section we’ll subclass NSView once again and create a class called PolygonView with some “holes” in it. It will draw a polygon with a specified number of sides (the range will be from 3 to 20 sides). We will use the ViewDemo project for a third time.
Back in IB with ViewDemo’s
MainMenu.nib, subclass NSView again by choosing IB’s Classes → Subclass NSView menu command.Change the name of the new subclass from “MyView” to “PolygonView”.
Select the BarView instance in the window titled “Window”, type Command-1, and change the class of the BarView to PolygonView in the NSView (Custom) Info window.
IB will alert you that “This operation will break existing connections” because the PolygonView does not respond to the takePercentageValue: message. Click OK.
Select the slider, type Command-1, and change the slider’s Minimum to 3, Maximum to 20, and Current to 3. Use the Tab key to jump from text field to text field.
In the Markers box, change the number of marks to 18 and click the Marker Values Only checkbox.
Select the PolygonView class in the
MainMenu.nibwindow, type Command-1, and then add the takeNumSidesFrom: action to the PolygonView class in the PolygonView Class Info panel.Connect the slider to the PolygonView instance so that it sends the takeNumSidesFrom: action message.
Select the PolygonView class in the
MainMenu.nibwindow and choose Classes → Create Files for PolygonView. Insert the class files into the ViewDemo project.Back ...
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