Motif Programmer's Guide Migration Version

Motif 2.1 Programmer's Guide

Managing Geometry Using RowColumn

In addition to its role as the menu widget, RowColumn provides general-purpose layout and geometry management for child widgets arranged in rows, columns, or grids. The default RowColumn type, XmWORK_AREA, provides the layout features but not the menu semantics.

RowColumn's layout is controlled by two sets of resources. One set determines the position of children within the parent. The other set specifies whether RowColumn adjusts the internal layout characteristics of the children, such as margins and text alignment.

The two primary resources that control child positioning are XmNorientation and XmNpacking. XmNorientation determines whether RowColumn lays out its children in rows or columns. When XmNorientation is XmVERTICAL--the default for a WorkArea--the layout is column-major. When XmNorientation is XmHORIZONTAL the layout is row-major.

XmNpacking controls the general style of the layout. The resource has three possible values:

XmPACK_TIGHT

RowColumn places children one after the other along the major dimension (for example, in a column when XmNorientation is XmVERTICAL). It proceeds until no more children fit along that dimension and then begins a new row or column. When XmNorientation is XmVERTICAL and the vertical distance remaining in the current column is too small to accommodate the child being placed, RowColumn begins a new column if XmNresizeHeight is False or the RowColumn cannot become larger. When placing children in a column, RowColumn does not alter their heights, but it makes the width of each child in the column equal to the width of the widest child in that column. Analogous rules apply to row-major layouts. XmPACK_TIGHT is the default value for XmNpacking in a WorkArea.

XmPACK_COLUMN

RowColumn makes the width and height of each child identical. The width is the maximum width of all children, and the height is the maximum height. RowColumn uses the value of XmNnumColumns to determine the maximum number of columns (in XmVERTICAL orientation) or rows (in XmHORIZONTAL orientation) to produce. RowColumn tries to create XmNnumColumns columns (or rows) with an equal number of children in each column (or row).

XmPACK_NONE

RowColumn does not change the position of any child. Unless XmNresizeWidth is False, it tries to grow large enough to enclose the greatest x extent of any child. Unless XmNresizeHeight is False, it tries to grow large enough to enclose the greatest y extent of any child.

Several other resources influence the position and size of children:

XmNadjustLast

This resource applies only when XmNpacking is XmPACK_TIGHT or XmPACK_COLUMN. When this resource is True and the orientation is vertical, RowColumn increases the widths of children in the last column when necessary so that all children extend to the right edge of the RowColumn. When this resource is True and the orientation is horizontal, RowColumn increases the heights of children in the last row when necessary so that all children extend to the bottom edge of the RowColumn.

XmNentryBorder

When this resource is nonzero, it specifies the border width for all children of the RowColumn. When this resource is zero, RowColumn does not alter the border width of its children.

XmNmarginHeight

This resource specifies the amount of space between the top edge of the RowColumn and the first item in each column, and between the bottom edge of the RowColumn and the last item in each column.

XmNmarginWidth

This resource specifies the amount of space between the left edge of the RowColumn and the first item in each row, and between the right edge of the RowColumn and the last item in each row.

XmNresizeHeight

When this resource is True, RowColumn adjusts its own height when possible to accommodate its children. When this resource is False, RowColumn does not request a new height during layout.

XmNresizeWidth

When this resource is True, RowColumn adjusts its own width when possible to accommodate its children. When this resource is False, RowColumn does not request a new width during layout.

XmNspacing

This resource applies only when XmNpacking is XmPACK_TIGHT or XmPACK_COLUMN. It specifies the amount of vertical space between each child in a vertical orientation and the amount of horizontal space between each child in a horizontal orientation.

RowColumn also has several resources that can cause the RowColumn to change the internal layout of some classes of children:

XmNadjustMargin

This resource applies only to children that are subclasses of XmLabel and XmLabelGadget. When this resource is True and the orientation is vertical, RowColumn sets the XmNmarginLeft and XmNmarginRight for all children to the maximum values for those resources among all children. When this resource is True and the orientation is horizontal, RowColumn sets the XmNmarginTop and XmNmarginBottom for all children to the maximum values for those resources among all children. In PopupMenus and PulldownMenus this resource adjusts the margins only for button children, not for labels.

XmNentryAlignment

This resource applies only to children that are subclasses of XmLabel and XmLabelGadget. When XmNisAligned is True, RowColumn sets the XmNalignment of all children to the value specified by XmNentryAlignment. Following are the possible values:

XmALIGNMENT_BEGINNING

The child's text or pixmap is aligned with the left edge of the child's window.

XmALIGNMENT_CENTER

The child's text or pixmap is aligned with the center of the child's window.

XmALIGNMENT_END

The child's text or pixmap is aligned with the right edge of the child's window.

In menus, RowColumn sets the alignment only for button children, not for labels.

XmNentryVerticalAlignment

This resource applies only to children that are subclasses of XmLabel, XmLabelGadget, XmText, and XmTextField. It also applies only when XmNpacking is XmPACK_COLUMN (in either orientation) or when XmNpacking is XmPACK_TIGHT and the orientation is horizontal. The value specifies a reference point for aligning the children in any row:

XmALIGNMENT_BASELINE_BOTTOM

Causes the last baseline of each child in a row to align with the last baseline of the tallest child in the row. This value is applicable only when all children in a row contain textual data.

XmALIGNMENT_BASELINE_TOP

Causes the first baseline of each child in a row to align with the first baseline of the tallest child in the row. This value is applicable only when all children in a row contain textual data.

XmALIGNMENT_BOTTOM

Causes the bottom edge of the last line of text contained in each child to align with the bottom edge of the last line of text of the tallest child in the row.

XmALIGNMENT_CENTER

Causes the center of each child to align vertically with the center point established by the tallest child in the row.

XmALIGNMENT_TOP

Causes the top edge of the first line of text contained in each child to align with the top edge of the first line of text of the tallest child in the row.

XmNisAligned

When True, RowColumn sets the XmNalignment resources of children that are subclasses of XmLabel or XmLabelGadget to the value specified by XmNentryAlignment.