ptr& = WNDBLK
This function returns a pointer to FutureBasic's internal Window Descriptor Block. The Window Descriptor Block is an array of Window Descriptors. Each Window Descriptor is a record which contains information about one of your program's windows; FutureBasic maintains a Window Descriptor for each window that you create using the
WINDOW statement. The structure of a Window Descriptor is as follows:
BEGIN RECORD wDescriptor
DIM wptr& 'Pointer to window record
DIM efdHeadH& 'Handle to the first Edit Field Descriptor
DIM activeEfH& 'Handle to active edit field
DIM clipH& 'Handle to window's clip region
wptr&element points to the window's window record, which is a structure that the MacOS Window Manager maintains for each open window. This is the same pointer that is returned by the
efdHeadH&element is a handle to the first Edit Field Descriptor for the window. There is an Edit Field Descriptor for each edit field or picture field in the window; see below for more information. If there are no edit fields nor picture fields in the window,
activeEfH&element is a handle to the currently active edit field or picture field (if any) in the window. This is the same as the handle returned by the
WINDOW(_efHandle)function when the window is active. If there is no active field in the window,
clipH&element is a handle to the window's clip region. However, if the window's
_noAutoClipattribute is set,
You can use the window's assigned ID number to determine the location of its Window Descriptor within the array. The first Window Descriptor in the array corresponds to "window #0," which is a special graphics port that is reserved for FutureBasic's internal use. The next element in the array corresponds to window #1; the next to window #2; and so on. Array elements that don't correspond to the ID of any existing window have undefined contents.
If you define a
wDescriptor record type as shown above, you can get a pointer to the Window Descriptor corresponding to window #
windowID as follows:
wdPtr& = WNDBLK + (windowID * SIZEOF(wDescriptor))
Alternatively, you can use
XREF to access the contents of the array using normal
FutureBasic3 array syntax:
wdArray& = WNDBLK
XREF wdArray AS wDescriptor
You can then use the syntax
wdArray(windowID) to access an individual Window
Edit Field DescriptorsFutureBasic maintains an Edit Field Descriptor for each field that you create using the
EDIT FIELD statement or the
PICTURE FIELD statement. For each window, there is a linked list of Edit Field Descriptors for the fields in that window; a handle to the first descriptor in the list can be found in the
efdHeadH& element of the Window Descriptor record. The structure of an Edit Field Desciptor is as follows:
BEGIN RECORD efDescriptor
DIM nextDescH&<spacer type="horizontal" size="134">'Handle to next descriptor in list
DIM indexRef%<spacer type="horizontal" size="141">'Field's ID number
DIM fieldType``<spacer type="horizontal" size="126">'Field's type
DIM jClass``'Text justification & class number
DIM teH&<spacer type="horizontal" size="15">'Handle to TextEdit record
nextDescH&element is a handle to the next Edit Field Descriptor in the list. If
nextDescH&is _nil, there are no more edit fields nor picture fields in this window.
indexRef%element is the field's ID number, as assigned by the
EDIT FIELDstatement or the
fieldType``element is the same as the type parameter specified in the
EDIT FIELDstatement or the
PICTURE FIELDstatement (it defaults to
_framedNoCR (1)if no type was explicitly specified).
jClass``element is the same as the
efClassparameter specified in the
EDIT FIELDstatement, or the justparameter specified in the
PICTURE FIELDstatement. It defaults to zero if the parameter wasn't specified.
teH&element is a handle to the field's TextEdit Record, which is a structure that the MacOS maintains for each open edit field. This is the same handle that is returned by the
TEHANDLE(efID)function. Note that FutureBasic associates a TextEdit Record with picture fields as well as edit fields; you can use a picture field's TextEdit Record, for example, to determine the field's rectangle. See the <a href="http://developer.apple.com/documentation/mac/Text/Text-40.html">"TextEdit" chapter</a> of <a href="http://developer.apple.com/documentation/macos8/mac8.html">Inside Macintosh</a>: <a href="http://developer.apple.com/documentation/mac/Text/Text-2.html">Text</a> for more information.
The following function returns a count of the number of edit fields and picture fields in a specified window. It assumes that the
efDescriptor record types have been defined as shown above.
LOCAL FN EfCount(wndID) DIM wdPtr AS POINTER TO wDescriptor DIM efdH AS HANDLE TO efDescriptor count = 0 IF WINDOW(-wndID) = 0 <b>THEN EXIT FN '(no such window) wdPtr = WNDBLK + (wndID * SIZEOF(wDescriptor)) efdH = wdPtr.efdHeadH& WHILE efdH <> _nil <spacer type="horizontal" size="48">INC(count) <spacer type="horizontal" size="48">efdH = efdH..nextDescH& WEND END FN = count
Window Descriptors are maintained only for windows that are created using the
WINDOW statement, and Edit Field Descriptors are maintained only for edit fields/picture fields that are created using the
EDIT FIELD or
PICTURE FIELD statement. If you create a window or an edit field using a MacOS Toolbox routine (such as NewWindow or TENew), there will be no Descriptor associated with it.