MacApp 2.0b5 View Architecture Release Notes

( MacApp 2.0bS View Architecture Release Notes Curt Bianchi Introduction This document describes the architecture for MacApp 2.0's view classes, and describes all methods and fields of the view classes defmed in UMacApp. This represents the major change between MacApp 1.x and MacApp 2.0. The motivations for introducing the new architecture are To simplify the architecture To provide a class that is suitable as the basis for all displayed objects, from windows to controls To have a single nesting and layering mechanism for display objects To support large coordinate systems To simplify the implementation of display objects within views, including controls and fields The MacApp 1.x Display Achitecture If you're already familiar with the MacApp 1.x display architecture, you should skip this section. If you're not, here it is in a nutshell. The old display architecture consists basically of three classes: TWindow, TF rame, and TView. TWindow A TWindow object represents a Window Manager window. As such, it handles opening, closing, moving, resizing, activating, and deactivating a window. TFrame A TFrame object is a rectangular area within a window, handling scrolling and coordinate transformations. TFrame objects are similar to QuickDraw grafports in that each has its own coordinate system. Frames typically tile windows. In the simplest case, windows have a single frame whose size is that of the window's content rectangle. However, windows can be subdivided into sections by using multiple frames. Furthermore, frames can be nested inside one another. Within frames are displayed Control Manager controls (for example, scroll bars) and a portion of a view, or a collection of subframes, or both. TView A TView object renders the display image of a document's data and responds to mouse clicks and keystrokes in the display image. It is a rectangular area of any size up to 30,000 pixels in each dimension. A view is always displayed in a frame. The frame's scroll bars determine what part of the view is actually visible, since large views cannot be displayed in their entirety. Wed, Aug 3, 1988 © 1988S Apple Computer 1 -o MDemoTeHt.p PROGRAM DemoText; USES {$LOAD Mac I ntf.LOAD} MemTypes, QuickDraw, OSI ntf, Tooll ntf, Pack I ntf, {$LOAD UMscApp.LOAD} UObject, ULfat, UMacApp, {$LOAD} UPri nti ng, tQ:. ~MN, ~ MDemoTeHt.p TWindow TFrame Niew PROGRAM DemoText; USES {$LOAD Mee I ntf.LOAD} MemTypes, QuickDraw, OSlntf, Toollntf, Pecklntf, {$LOAD UMecApp.LOAD} UObject, Ulist, UMecApp, {$LOAD} UPri nti ng, UTEView, UDemoText; VAR gDemoTextApplication: TDemoTextA ppli ceti on; {$S Main} BEGIN I nitTool box( 8); I nit Printing; New(gDemoTextApplication); gDemoTextApplicetion .I De moTextAppl ication; gDe moTextAp plication.Run; END. Figure l: Old MacApp Display Architecture Wed.Aug 3.1988 © 1988 S Apple Computer 2 Figure 1 shows a typical text edit window and the MacApp objects used to build it. Here, the TWindow object displays the grow icon (…