.\" $Xorg: List,v 1.3 2000/08/17 19:42:27 cpqbld Exp $ .NH 2 List Widget .LP .XS List Widget .XE .IN "List widget" "" "@DEF@" .Ds 0 .TA 2.0i .ta 2.0i .sp Application header file .IN "List.h" "" Class header file .IN "ListP.h" "" Class listWidgetClass .IN "listWidgetClass" "" Class Name List .IN "List widget" "class name" Superclass Simple .sp .De .LP The List widget contains a list of strings formatted into rows and columns. When one of the strings is selected, it is highlighted, and the List widget's \fBNotify\fP action is invoked, calling all routines on its callback list. Only one string may be selected at a time. .NH 3 Resources .LP When creating a List widget instance, the following resources are retrieved from the argument list or from the resource database: .LP .IN "List widget" "resources" .TS H expand; lw(1i) lw(1i) lw(1i) lw(.5i) lw(2i). _ .sp 3p .TB Name Class Type Notes Default Value .sp 3p _ .TH .R .sp 3p accelerators Accelerators AcceleratorTable NULL ancestorSensitive AncestorSensitive Boolean D True background Background Pixel XtDefaultBackground backgroundPixmap Pixmap Pixmap XtUnspecifiedPixmap borderColor BorderColor Pixel XtDefaultForeground borderPixmap Pixmap Pixmap XtUnspecifiedPixmap borderWidth BorderWidth Dimension 1 callback Callback Callback NULL colormap Colormap Colormap Parent's Colormap columnSpacing Spacing Dimension 6 cursor Cursor Cursor XC_left_ptr cursorName Cursor String NULL defaultColumns Columns int 2 depth Depth int C Parent's Depth destroyCallback Callback XtCallbackList NULL font Font FontStruct XtDefaultFont fontSet FontSet XFontSet XtDefaultFontSet forceColumns Columns Boolean False foreground Foreground Pixel XtDefaultForeground height Height Dimension A Enough space to contain the list insensitiveBorder Insensitive Pixmap GreyPixmap internalHeight Height Dimension 2 internalWidth Width Dimension 4 international International Boolean C False list List Pointer name of widget longest Longest int A 0 mappedWhenManaged MappedWhenManaged Boolean True numberStrings NumberStrings int A computed for NULL terminated list pasteBuffer Boolean Boolean False pointerColor Foreground Pixel XtDefaultForeground pointerColorBackground Background Pixel XtDefaultBackground rowSpacing Spacing Dimension 2 screen Screen Screen R Parent's Screen sensitive Sensitive Boolean True translations Translations TranslationTable See below verticalList Boolean Boolean False width Width Dimension A Enough space to contain the list x Position Position 0 y Position Position 0 .sp 3p _ .TE .Ac .As .Bg .Gp .Bc .Bp .Bw .IP \fBcallback\fP 1.5i All functions on this list are called whenever the \fBnotify\fP action is invoked. The \fIcall_data\fP argument contains information about the element selected and is described in detail in the \fBList Callbacks\fP section. .Cm .IP \fBcolumnSpacing\fP 1.5i .br .ns .IP \fBrowSpacing\fP 1.5i The amount of space, in pixels, between each of the rows and columns in the list. .Cu .Cn .IP \fBdefaultColumns\fP 1.5i The default number of columns. This value is used when neither the width nor the height of the List widget is specified or when \fBforceColumns\fP is \fBTrue\fP. .Dp .Dc .IP \fBfont\fP The text font to use when displaying the \fBlist\fP, when the \fBinternational\fP resource is \fBfalse\fP. .IP \fBfontSet\fP The text font set to use when displaying the \fBlist\fP, when the \fBinternational\fP resource is \fBtrue\fP. .IP \fBforceColumns\fP Forces the default number of columns to be used regardless of the List widget's current size. .IP \fBforeground\fP 1.5i A pixel value which indexes the widget's colormap to derive the color used to paint the text of the list elements. .Hw .Ib .IP \fPinternalHeight\fP 1.5i .br .ns .IP \fPinternalWidth\fP 1.5i The margin, in pixels, between the edges of the list and the corresponding edge of the List widget's window. .IP \fBlist\fP 1.5i An array of text strings displayed in the List widget. If \fBnumberStrings\fP is zero (the default) then the \fBlist\fP must be NULL terminated. If a value is not specified for the \fBlist\fP, then \fBnumberStrings\fP is set to 1, and the name of the widget is used as the \fBlist\fP, and \fBlongest\fP is set to the length of the name of the widget. The \fBlist\fP is used in place, and must be available to the List widget for the lifetime of this widget, or until it is changed with \fBXtSetValues\fP or \fBXawListChange\fP. .In .IP \fBlongest\fP Specifies the width, in pixels, of the longest string in the current list. The List widget will compute this value if zero (the default) is specified. If this resource is set by hand, entries longer than this will be clipped to fit. .Mm .IP \fBnumberStrings\fP 1.5i The number of strings in the current list. If a value of zero (the default) is specified, the List widget will compute it. When computing the number of strings the List widget assumes that the \fBlist\fP is NULL terminated. .IP \fBpasteBuffer\fP 1.5i If this resource is set to \fBTrue\fP then the name of the currently selected list element will be put into \fBCUT_BUFFER_0\fP. .Pf .Pb .Sc .Se .Tr .IP \fBverticalList\fP 1.5i If this resource is set to \fBTrue\fP then the list elements will be presented in column major order. .Xy .NH 3 List Actions .IN "List widget" "actions" .LP The List widget supports the following actions: .IP \(bu 5 Highlighting and unhighlighting the list element under the pointer with \fBSet\fP and \fBUnset\fP .IP \(bu 5 Processing application callbacks with \fBNotify\fP .LP The following is the default translation table used by the List Widget: .IN "List widget" "default translation table" .LP .Ds .TA .5i 2.25i .ta .5i 2.25i ,: Set(\|) Notify(\|) .sp .De .LP The full list of actions supported by List widget is: .IP \fBSet\fP(\|) 1.5i \fISets\fP the list element that is currently under the pointer. To inform the user that this element is currently set, it is drawn with foreground and background colors reversed. If this action is called when there is no list element under the cursor, the currently \fIset\fP element will be \fIunset\fP. .IP \fBUnset\fP(\|) 1.5i Cancels the \fIset\fP state of the element under the pointer, and redraws it with normal foreground and background colors. .IP \fBNotify\fP(\|) 1.5i Calls all callbacks on the List widget's callback list. Information about the currently selected list element is passed in the \fIcall_data\fP argument (see \fBList Callbacks\fP below). .NH 3 List Callbacks .IN "List widget" "callbacks" .LP All procedures on the List widget's callback list will have a \fBXawListReturnStruct\fP passed to them as \fIcall_data\fP. The structure is defined in the List widget's application header file. .LP .Ds 0 .TA .5i 2.25i .ta .5i 2.25i .IN "XawListReturnStruct" "" "@DEF@" typedef struct _XawListReturnStruct { String string; /* string shown in the list. */ int list_index; /* index of the item selected. */ } XawListReturnStruct; .IN "XawListReturnStruct" "" .NT The \fIlist_index\fP item used to be called simply \fIindex\fP. Unfortunately, this name collided with a global name defined on some operating systems, and had to be changed. .NE .De .NH 3 Changing the List .LP To change the list that is displayed, use .PN XawListChange . .IN "XawListChange" "" "@DEF@" .FD 0 void XawListChange(\fIw\fP, \fIlist\fP, \fInitems\fP, \fIlongest\fP, \fIresize\fP) .br Widget \fIw\fP; .br String * \fIlist\fP; .br int \fInitems\fP, \fIlongest\fP; .br Boolean \fIresize\fP; .FN .IP \fIw\fP 1i Specifies the List widget. .IP \fIlist\fP 1i Specifies the new list for the List widget to display. .IP \fInitems\fP 1i Specifies the number of items in the \fIlist\fP. If a value less than 1 is specified, \fIlist\fP must be NULL terminated, and the number of items will be calculated by the List widget. .IP \fIlongest\fP 1i Specifies the length of the longest item in the \fIlist\fP in pixels. If a value less than 1 is specified, the List widget will calculate the value. .IP \fIresize\fP 1i Specifies a Boolean value that if \fBTrue\fP indicates that the List widget should try to resize itself after making the change. The constraints of the List widget's parent are always enforced, regardless of the value specified here. .LP .PN XawListChange will \fIunset\fP all list elements that are currently \fBset\fP before the list is actually changed. The \fIlist\fP is used in place, and must remain usable for the lifetime of the List widget, or until \fIlist\fP has been changed again with this function or with \fBXtSetValues\fP. .NH 3 Highlighting an Item .LP To highlight an item in the list, use .PN XawListHighlight . .IN "XawListHighlight" "" "@DEF@" .FD 0 void XawListHighlight(\fIw\fP, \fIitem\fP) .br Widget \fIw\fP; .br int \fIitem\fP; .FN .IP \fIw\fP 1i Specifies the List widget. .IP \fIitem\fP 1i Specifies an index into the current list that indicates the item to be highlighted. .LP Only one item can be highlighted at a time. If an item is already highlighted when .PN XawListHighlight is called, the highlighted item is unhighlighted before the new item is highlighted. .NH 3 Unhighlighting an Item .LP To unhighlight the currently highlighted item in the list, use .PN XawListUnhighlight . .IN "XawListUnhighlight" "" "@DEF@" .FD 0 void XawListUnhighlight(\fIw\fP) .br Widget \fIw\fP; .FN .IP \fIw\fP 1i Specifies the List widget. .NH 3 Retrieving the Currently Selected Item .LP To retrieve the list element that is currently \fIset\fP, use .PN XawListShowCurrent . .IN "XawListShowCurrent" "" "@DEF@" .FD 0 XawListReturnStruct *XawListShowCurrent(\fIw\fP) .br Widget \fIw\fP; .FN .IP \fIw\fP 1i Specifies the List widget. .LP .PN XawListShowCurrent returns a pointer to an .PN XawListReturnStruct structure, containing the currently highlighted item. If the value of the index member is XAW_LIST_NONE, .IN "XAW_LIST_NONE" the string member is undefined, and no item is currently selected. .NH 3 Restrictions .LP Many programmers create a ``scrolled list'' by putting a List widget with many entries as a child of a Viewport widget. The List continues to create a window as big as its contents, but that big window is only visible where it intersects the parent Viewport's window. (I.e., it is ``clipped.'') .LP While this is a useful technique, there is a serious drawback. X does not support windows above 32,767 pixels in width or height, but this height limit will be exceeded by a List's window when the List has many entries (i.e., with a 12 point font, about 3000 entries would be too many.) .LP