(3)

NAME
XfwfRowCol

DESCRIPTION
The RowCol widget forces all its children into rows and columns. The children keep their preferred size, but the preferred position is ignored. Resources determine how many rows or columns their should be (or as many as will fit) and if the children should be layed out in rows or in columns. In both methods, the children are placed on a grid, the size of which is determined by the width (height) of the widest (tallest) child. The children can be aligned in several ways: they can be placed in the center of their grid cell or against the edges. This is controlled by a resource of type Alignment.

  Public variables
XfwfRowCol
Name | Class | Type | Default
XtNstoreByRow | XtCStoreByRow | Boolean | True
XtNrows | XtCRows | Int | 0
XtNcolumns | XtCColumns | Int | 0
XtNalignment | XtCAlignment | Alignment | XfwfTopLeft
XtNshrinkToFit | XtCShrinkToFit | Boolean | False

XtNstoreByRow
    The child widgets can be layed out in rows (left to right) or in columns (top to bottom). The resource storeByRow can be True or False. True means children are added to the right of the previous one until the row is full, like words are added to a text. False means children are added below the previous one, until the column is full.
    Boolean  storeByRow = True

XtNrows
    The number of rows can be set with rows, or the number of columns can be set with columns. If both are non-zero, rows will be ignored. If rows is zero, there will be as many rows as needed. If columns is zero, there will be as many columns as needed. However, if both are zero, there will be as many columns as will fit in the current width of the RowCol widget. By default, both rows and columns are zero.
    int  rows = 0

XtNcolumns
    int  columns = 0

XtNalignment
    The area of the RowCol widget is partitioned into rectangular cells (a grid). The cells are just large enough to contain the widest and the tallest of the children. Within the cell, the children can be put in the top left corner (the default) or against one of the edges or in the center. This is set with the alignment resource. The type Alignment is defined in the ancestor class `Common'.
    Alignment  alignment = XfwfTopLeft

XtNshrinkToFit
    The resource shrinkToFit determines how the size of the RowCol widget itself is computed. When it is False (default), the location resource is used to compute the widget's preferred size. When the value is True, the preferred size is computed fromthe total width and height of the children. For example, when the widest child has a width of w and columns > 0, the preferred width will be columns * w + frame width. A similar computation is used for the height. If columns > 0, only the height is computed this way. If columns = 0, rows > 0, only the width is computed.
    Boolean  shrinkToFit = False

XtNframeType
    The inherited resource frameType is given a default value of XfwfSunken, instead of the inherited default XfwfRaised. The frame width is set to a default of 2 pixels, instead of 0.
     frameType = XfwfSunken

XtNframeWidth
     frameWidth = 2
    XfwfBoard
    Name | Class | Type | Default
    XtNabs_x | XtCAbs_x | Position | 0
    XtNrel_x | XtCRel_x | Float | "0.0"
    XtNabs_y | XtCAbs_y | Position | 0
    XtNrel_y | XtCRel_y | Float | "0.0"
    XtNabs_width | XtCAbs_width | Position | 0
    XtNrel_width | XtCRel_width | Float | "1.0"
    XtNabs_height | XtCAbs_height | Position | 0
    XtNrel_height | XtCRel_height | Float | "1.0"
    XtNhunit | XtCHunit | Float | "1.0"
    XtNvunit | XtCVunit | Float | "1.0"
    XtNlocation | XtCLocation | String | NULL
    XfwfFrame
    Name | Class | Type | Default
    XtNcursor | XtCCursor | Cursor | None
    XtNframeType | XtCFrameType | FrameType | XfwfRaised
    XtNframeWidth | XtCFrameWidth | Dimension | 0
    XtNouterOffset | XtCOuterOffset | Dimension | 0
    XtNinnerOffset | XtCInnerOffset | Dimension | 0
    XtNshadowScheme | XtCShadowScheme | ShadowScheme | XfwfAuto
    XtNtopShadowColor | XtCTopShadowColor | Pixel | compute_topcolor
    XtNbottomShadowColor | XtCBottomShadowColor | Pixel | compute_bottomcolor
    XtNtopShadowStipple | XtCTopShadowStipple | Bitmap | NULL
    XtNbottomShadowStipple | XtCBottomShadowStipple | Bitmap | NULL
    XfwfCommon
    Name | Class | Type | Default
    XtNtraversalOn | XtCTraversalOn | Boolean | True
    XtNhighlightThickness | XtCHighlightThickness | Dimension | 2
    XtNhighlightColor | XtCHighlightColor | Pixel | XtDefaultForeground
    XtNhighlightPixmap | XtCHighlightPixmap | Pixmap | None
    XtNnextTop | XtCNextTop | Callback | NULL
    XtNuserData | XtCUserData | Pointer | NULL
    Composite
    Name | Class | Type | Default
    XtNchildren | XtCChildren | WidgetList | NULL
    insertPosition | XtCInsertPosition | XTOrderProc | NULL
    numChildren | XtCNumChildren | Cardinal | 0
    Core
    Name | Class | Type | Default
    XtNx | XtCX | Position | 0
    XtNy | XtCY | Position | 0
    XtNwidth | XtCWidth | Dimension | 0
    XtNheight | XtCHeight | Dimension | 0
    borderWidth | XtCBorderWidth | Dimension | 0
    XtNcolormap | XtCColormap | Colormap | NULL
    XtNdepth | XtCDepth | Int | 0
    destroyCallback | XtCDestroyCallback | XTCallbackList | NULL
    XtNsensitive | XtCSensitive | Boolean | True
    XtNtm | XtCTm | XTTMRec | NULL
    ancestorSensitive | XtCAncestorSensitive | Boolean | False
    accelerators | XtCAccelerators | XTTranslations | NULL
    borderColor | XtCBorderColor | Pixel | 0
    borderPixmap | XtCBorderPixmap | Pixmap | NULL
    background | XtCBackground | Pixel | 0
    backgroundPixmap | XtCBackgroundPixmap | Pixmap | NULL
    mappedWhenManaged | XtCMappedWhenManaged | Boolean | True
    XtNscreen | XtCScreen | Screen * | NULL

  Private variables
The width of the widest and the height of the tallest child are kept in private variables, for quicker access.
Dimension  max_width
Dimension  max_height

  Methods
If a child becomes managed or unmanaged, the RowCol widget recomputes the positions of all managed children. That is done by a method layout. In the process, the widget may ask its parent for a different size if shrinkToFit = True.
change_managed($)
{
    $layout($, $shrinkToFit);
}
The layout function is responsible for moving the children to their positions in the grid. It is called from change_managed, geometry_manager and resize. The function first computes the maximum width and height of all the children, including their borders. Then it computes the number of rows and columns. All children are moved to their proper positions with the help of a utility function align_child, which aligns a child widget to the grid. If shrink = True, the RowCol widget also asks its parent for a new width and/or height, depending on the resulting layout.
layout($, int  shrink)
{
    int nrows, ncols, i, nchild, n;
    Position left, top, x, y;
    Dimension width, height, w, h;
    Widget child;
    nchild = 0;
    $max_width = 0;
    $max_height = 0;
    for (i = 0; i < $num_children; i++) {
	child = $children[i];
	if (! XtIsManaged(child)) continue;
	nchild++;
	$max_width = max($max_width, $child$width + 2*$child$border_width);
	$max_height = max($max_height, $child$height + 2*$child$border_width);
    }
    $compute_inside($, left, top, width, height);
    if ($columns != 0) {
	ncols = $columns;
	nrows = (nchild + ncols - 1)/ncols;
    } else if ($rows != 0) {
	nrows = $rows;
	ncols = (nchild + nrows - 1)/nrows;
    } else {
	ncols = $max_width != 0 ? width/$max_width : 1;
	if (ncols == 0) ncols = 1;
	nrows = (nchild + ncols - 1)/ncols;
    }
    x = left;
    y = top;
    n = 0;
    if ($storeByRow) {
	for (i = 0; i < $num_children; i++) {
	    child = $children[i];
	    if (! XtIsManaged(child)) continue;
	    align_child(child, x, y, $max_width, $max_height, $alignment);
	    n++;
	    if (n == ncols) {
		n = 0;
		x = left;
		y += $max_height;
	    } else
		x += $max_width;
	}
    } else {
	for (i = 0; i < $num_children; i++) {
	    child = $children[i];
	    if (! XtIsManaged(child)) continue;
	    align_child(child, x, y, $max_width, $max_height, $alignment);
	    n++;
	    if (n == nrows) {
		n = 0;
		y = top;
		x += $max_width;
	    } else
		y += $max_height;
	}
    }
    if (shrink) {
	w = 2*left + ncols * $max_width;
	h = 2*top + nrows * $max_height;
	if ($columns != 0)
	    XtVaSetValues($, XtNwidth, w, XtNheight, h, NULL);
	else
	    XtVaSetValues($, XtNheight, h, NULL);
    }
}
When a child wants to change its size or border width, it calls its parent's geometry_manager method (through a call to XtMakeGeometryRequest or XtMakeResizeRequest.) The RowCol widget always grants size changes to its children. The size change is carried out immediately and a new layout is computed. If a child requests a change of position, the request is denied. A request for a change in stacking order is ignored.
XtGeometryResult  geometry_manager(Widget  child, XtWidgetGeometry * request, XtWidgetGeometry * reply)
{
    Dimension newwd, newht, newbd;
    if (request->request_mode  (CWX | CWY)) return XtGeometryNo;
    if (request->request_mode  XtCWQueryOnly) return XtGeometryYes;
    newwd = request->request_mode  CWWidth ? request->width : $child$width;
    newht = request->request_mode  CWHeight ? request->height : $child$height;
    newbd = request->request_mode  CWBorderWidth
	? request->border_width : $child$border_width;
    if (newwd == $child$width  newht == $child$height
	 newbd == $child$border_width) return XtGeometryNo;
    XtResizeWidget(child, newwd, newht, newbd);
    $layout($, $shrinkToFit);
    return XtGeometryDone;
}
The resize method is called when the widget is resized. If the rows and columns resources are both zero, the children will have to be be re-aligned. In this case, there is no sense in asking the parent for a new size, so layout is passed a value of False.
resize($)
{
    if ($rows == 0  $columns == 0) $layout($, False);
}
The initialize method sets the private variables, in this case only max_width and max_height. There is no need to check if the resources have sensible values.
initialize(Widget  request, $, ArgList  args, Cardinal * num_args)
{
    $max_width = $max_height = 0;
}
The RowCol widget needs to recompute the positions of the children when one of the resources changes. When the layout changes, the widget also needs to be redrawn, of course. The private variables are not dependent on the resources, so they don't need recomputing.
Boolean  set_values(Widget  old, Widget  request, $, ArgList  args, Cardinal * num_args)
{
    Boolean need_layout = False;
    Boolean need_redisplay = False;
    if ($old$storeByRow != $storeByRow) need_layout = True;
    if ($old$rows != $rows) need_layout = True;
    if ($old$columns != $columns) need_layout = True;
    if ($old$alignment != $alignment) need_layout = True;
    if ($old$shrinkToFit != $shrinkToFit) need_layout = True;
    if (need_layout) {
	$layout($, $shrinkToFit);
	need_redisplay = True;
    }
    return need_redisplay;
}

Utilities
char  rcsid[] = "$Header: RowCol.w,v 1.1 92/10/14 18:36:36 bert Exp $"
align_child puts a widget in the proper position in the cell given by cx, cy, width and height.
align_child($, int  cx, int  cy, int  width, int  height, Alignment  alignment)
{
    Position x, y;
    if (alignment  XfwfLeft) x = cx;
    else if (alignment  XfwfRight) x = cx + width - $width;
    else x = cx + (width - $width) / 2;
    if (alignment  XfwfTop) y = cy;
    else if (alignment  XfwfBottom) y = cy + height - $height;
    else y = cy + (height - $height) / 2;
    XtMoveWidget($, x, y);
}