a660d684ed
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@11 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
98 lines
5.5 KiB
TeX
98 lines
5.5 KiB
TeX
\chapter{Technical notes}\label{technotes}
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\setheader{{\it CHAPTER \thechapter}}{}{}{}{}{{\it CHAPTER \thechapter}}%
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\setfooter{\thepage}{}{}{}{}{\thepage}%
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\section{Overview}
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The dialog editor is written as a library, to be invoked by other programs. As you can see,
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dialoged.cc is a very small program which invokes the main window via a wxResourceManager
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object. The wxResourceManager object controls the user interface and other aspects
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of the dialog editor.
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There is wxResourceTable object in wxResourceManager: this contains a list of
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all the wxItemResources currently being edited. wxResourceTable and wxItemResource
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are classes already in wxWindows, defined in wx\_res.h. In order to edit a new
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dialog box, the dialog is created, and the existing event handler is temporarily replaced
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with a new one which defines editing functionality. This allows existing dialogs - even
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instances of subclasses of wxDialogBox - to be edited, the application-specific functionality
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being temporarily taken over by the dialog editor.
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In order to edit the properties of a dialog box or item, a property list editor is invoked.
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This uses the property classes from utils/wxprop. In order to map between properties and the
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actual window API, such as SetSize and GetSize, a `proxy' class called wxPropertyInfo
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has been defined, with a subclass for each class of wxWindows window to be edited.
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This class defines the main members SetProperty, GetProperty, GetPropertyNames,
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which transform the normal API into `property' terms.
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Properties are mostly extracted directly from the window being edited. This is
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in contrast with wxBuilder, where everything is stored in a set of parallel
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data structures, and windows `properties' only only set. However, there
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are exceptions to this rule in the dialog editor. There {\it is} in fact a set of
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parallel objects, the wxItemResource objects which can be seen listed in
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the main Dialog Editor window as a dialog is built up. These usually parallel
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the properties in the windows, but occasionally this is not possible. For example,
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all dialog boxes being edited must be modeless: or the user would not be
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able to access other windows. However, the user must be able to specify that
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when used in an application, that dialog box will be modal. In this case,
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the value in the wxItemResource will not match that in the actual dialog box.
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There is a major problem with taking values directly from the windows: this
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information sometimes does not match what went in. In Motif and XView,
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size values returned are not the same as those given. This causes speedy
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`degeneration' of window properties. Under Windows, properties are almost
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always consistent. The other platforms will need to be catered for by
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relying more on the wxItemResource objects, and not taking size
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information directly from windows.
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\subsection{Dynamic setting versus recreation}
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The property editor scheme relies on being able to set window properties
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dynamically: the user changes a value, and the window changes immediately
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to reflect the new value. Unfortunately, not all properties can be
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changed dynamically in wxWindows; for example, in Motif, the label position
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must be given at panel item creation time, because the way the widgets
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are laid out depend on the label position. The label position cannot then
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be changed without deleting and recreating the item.
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Hence the dialog editor takes two approaches: where values are dynamically
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settable, this is done. Where they are not, the item is deleted and recreated,
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after all existing values have been transferred into the parallel wxItemResource
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object. Therefore in wx\_rprop.cc, some of the SetProperty implementations have one or
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more call to RecreateWindowFromResource.
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\section{Resource associations}
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wxItemResource objects (containing information about panel items and dialogs) are not visual
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objects. However, they need to be associated with the visual objects when the latter
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are created for editing purposes. Therefore there is a hash table called resourceAssociations
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in wxResourceManager. When a window is created, the resource pointer and window pointer
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are associated via the hash table. When the window is deleted, the association is removed.
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Children of a dialog are associated with child wxItemResource objects by calling
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wxFindWindowByName with the wxItemResource name.
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\section{What needs to be done for XView and Motif}
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The following areas need attention before Dialog Editor will run properly on these platforms.
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\begin{enumerate}\itemsep=0pt
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\item For XView, the property editor needs to be made a modeless, not modal dialog, which has
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implications for flow of control in wxPropertyInfo::Edit.
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\item Properties which do not return the same value they are set to, such as width and height,
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need to be stored directly in wxItemResource and {\it not} transferred from window to wxItemResource
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in wxWindowPropertyInfo::InstantiateResource.
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\item Properties which cannot be dynamically set in XView or Motif need to have the item recreated (e.g. labelOrientation).
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\end{enumerate}
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\section{Files}
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The Dialog Editor source files are as follows:
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\begin{itemize}\itemsep=0pt
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\item wx\_rprop.h, wx\_rprop.cc: handle property setting and getting through the `proxy' wxPropertyInfo
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classes and using the property list editor from utils/wxprop.
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\item wx\_resed.h, wx\_resed.cc: the main implementation, in particular the wxResourceManager class.
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\item wx\_reswr.cc: resource writing code.
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\item wx\_repal.cc: the dialog editor palette implementation.
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\item dialoged.h, dialoged.cc: small `stub' for invoking the user interface via a wxResourceManager object.
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\end{itemize}
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