51 lines
2.6 KiB
HTML
51 lines
2.6 KiB
HTML
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<TITLE>BCursor Use Cases and Implementation Details</TITLE>
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<H1>BCursor Use Cases and Implementation Details:</H1>
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<P>This document describes the BCursor interface and some basics of how it is implemented.
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The document has the following sections:</P>
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<OL>
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<LI><A HREF="#interface">BCursor Interface</A></LI>
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<LI><A HREF="#usecases">BCursor Use Cases</A></LI>
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<LI><A HREF="#implement">BCursor Implementation</A></LI>
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</OL>
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<A NAME="interface"></A><H2>BCursor Interface:</H2>
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<P>The BCursor class is a simple class used to represent a mouse cursor as an object instead of an array of pixel data. The best source of information for the BCursor interface can be found
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<A HREF="file:///boot/beos/documentation/Be%20Book/The%20Application%20Kit/Cursor.html">here in the Be Book</A>.
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</P>
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<A NAME="usecases"></A><H2>BCursor Use Cases:</H2>
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<P>The following use cases cover the BCursor functionality:</P>
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<OL>
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<LI><P><B>Construction 1:</B> The first BCursor constructor requires a pointer to the pixel data. The format for the pixel data is described
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<A HREF="file:///boot/beos/documentation/Be%20Book/The%20Application%20Kit/Cursor.html#Cursor_Data_Format">here in the Be Book</A>.
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This pixel data is used to initialize the BCursor, but BCursor does not take ownership of the data, therefore you are responsible for freeing the memory after construction.</P></LI>
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<LI><P><B>Construction 2:</B> The second BCursor constructor requires a BMessage as an archive, however BCursor does not currently support archiving. Do not use this constructor.</P></LI>
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<LI><P><B>Destruction:</B> This releases all resources used by the BCursor.</P></LI>
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<LI><P><B>Instantiate:</B> This always returns NULL since it relies on the second constructor (which is not currently supported). If it were implemented, this would return a new BArchivable consisting of a BCursor created from the archive passed in as an argument. </P></LI>
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</OL>
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<A NAME="implement"></A><H2>BCursor Implementation:</H2>
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<P>All meaningful work of the BCursor is implemented in the first constructor. The constructor establishes a link with the app_server and sends it the pixel data. The app_server provides the BCursor with a token which identifies the pixel data. When BApplication::SetCursor(BCursor) is called, it must get the needed cursor data by obtaining the BCursor's token (BApplication is a friend of BCursor) and using the token to request the data from the app_server. Note that BCursor does not internally store the pixel data.</P>
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