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58 lines
2.6 KiB
Text
58 lines
2.6 KiB
Text
@paragraphindent 0
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@node Basic Classes
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@chapter Basic Classes
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This is a simple introduction to the major classes in the GNUstep GUI library
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API. If you know nothing about the OpenStep AppKit, it could be a good idea
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to read this before you start reading the reference documentation.
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I am very interested in comments regarding this text, particularly from people
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who are new to the OPENSTEP AppKit API. Send comments and/or suggestions to
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Nicola Pero (n.pero@@mi.flashnet.it).
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@section NSView
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@cindex NSView class
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NSView is the class of objects representing a rectangular area (usually in a
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window) with its own coordinate system. Views have methods to draw inside the
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view, to change the view's coordinate system, and to place the view with
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arbitrary position and size inside another view. When you place a view inside
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another view, you are technically making the smaller view a <em>subview</em>
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of the bigger view. The whole drawable area inside the window itself is
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represented by a view, called the <em>content view</em>. All the visible
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views in a window are then subviews of the content view of that window (or of
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the content view's subviews etc). This gives rise to what is called the "view
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tree" of the window.
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@section NSCell
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@cindex NSCell class
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NSCell is the class of objects representing a single amount of displayable
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data. For example, a cell could represent a number, or a string, or an image.
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Cells have methods to draw the data they represent in a view, to change the
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way the data is to be drawn (eg the font for a string or the border for an
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image), and to let the user interact directly (eg editing the data) with the
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data in a view.
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@section NSControl
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@cindex NSControl class
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NSControl is the class of objects representing a view (i.e., a rectangular
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area in a window) used to manage one or more cells (i.e., some displayable
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data). This class is usually designed to work with a subclass of NSCell,
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called <em>NSActionCell</em>, through a system of target/action. Each
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actioncell has a <em>target</em> - an object - and an <em>action</em> - a
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selector - both of which can be arbitrarily set. The control can then ask the
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cell to send its action to its target (ie, to invoke the method of the target
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object identified by the selector) as a consequence of user actions in the
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control. The typical example is a button: a button is a control with a
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corresponding cell; when the user presses the button, the buttoncell sends its
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action to its target. Controls are the high-level objects the you usually
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deal with when designing everyday-life user interfaces. You do not usually
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need to bother about cells, because the controls manage the cells for you.
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@page
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