Add calculator and missing header files

Change type name from twin_layout_t to twin_box_dir_t Create new
    twin_widget_layout_t holding layout preferences. Add copy_geom field to
    widget to make widgets look the same Add button signals and signal
    proc. Fix box layout to sum stretch along axis and minimize normal
Add calculator demo

12 files changed, 494 insertions, 122 deletions

diff --git a/ChangeLog b/ChangeLog
index 3992356..e20625d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,31 @@
+2004-10-27  Keith Packard  <keithp@keithp.com>
+
+	* Makefile.am:
+	Add calculator and missing header files
+	
+	* twin.h:
+	* twin_box.c: (_twin_box_init), (_twin_box_query_geometry),
+	(_twin_box_configure), (_twin_box_dispatch), (twin_box_create):
+	* twin_button.c: (_twin_button_dispatch), (_twin_button_init):
+	* twin_toplevel.c: (_twin_toplevel_init):
+	* twin_widget.c: (_twin_widget_dispatch), (_twin_widget_init),
+	* twin_label.c: (_twin_label_query_geometry),
+	(_twin_label_dispatch), (_twin_label_init):
+	* twinint.h:
+	(twin_widget_create):
+	Change type name from twin_layout_t to twin_box_dir_t
+	Create new twin_widget_layout_t holding layout preferences.
+	Add copy_geom field to widget to make widgets look the same
+	Add button signals and signal proc.
+	Fix box layout to sum stretch along axis and minimize normal
+	
+	* twin_calc.c: (_twin_calc_button_to_id),
+	(_twin_calc_update_value), (_twin_calc_push), (_twin_calc_pop),
+	(_twin_calc_digit), (_twin_calc_button_signal), (twin_calc_start):
+	* twin_calc.h:
+	* xtwin.c: (main):
+	Add calculator demo
+
 2004-10-26  Keith Packard  <keithp@keithp.com>
 
 	* twin_button.c: (_twin_button_paint):
diff --git a/Makefile.am b/Makefile.am
index 78b41b7..547a2f9 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -44,11 +44,18 @@ xtwin_SOURCES = \
 	twin_window.c \
 	twin_work.c \
 	twin_x11.c \
+	twin_x11.h \
 	twinint.h \
 	twin_clock.c \
+	twin_clock.h \
+	twin_calc.c \
+	twin_calc.h \
 	twin_text.c \
+	twin_text.h \
 	twin_demo.c \
+	twin_demo.h \
 	twin_hello.c \
+	twin_hello.h \
 	xtwin.c
 
 xtwin_LDADD = @X_LIBS@ -lm
diff --git a/twin.h b/twin.h
index 3f71940..f425c5f 100644
--- a/twin.h
+++ b/twin.h
@@ -372,37 +372,42 @@ typedef struct _twin_box    twin_box_t;
 #define _twin_widget_height(w)	(((twin_widget_t *)(w))->extents.bottom - \
 				 ((twin_widget_t *)(w))->extents.top)
 
+typedef enum _twin_box_dir {
+    TwinBoxHorz, TwinBoxVert
+} twin_box_dir_t;
+
 typedef enum _twin_dispatch_result {
-    TwinDispatchNone,
-    TwinDispatchPaint,
-    TwinDispatchConfigure,
+    TwinDispatchDone,
+    TwinDispatchContinue
 } twin_dispatch_result_t;
 
-typedef enum _twin_layout {
-    TwinLayoutHorz, TwinLayoutVert
-} twin_layout_t;
-
 typedef twin_dispatch_result_t (*twin_dispatch_proc_t) (twin_widget_t *widget,
 							twin_event_t *event);
 		       
+typedef struct _twin_widget_layout {
+    twin_coord_t	    width;
+    twin_coord_t	    height;
+    twin_stretch_t	    stretch_width;
+    twin_stretch_t	    stretch_height;
+} twin_widget_layout_t;
+
 struct _twin_widget {
     twin_window_t	    *window;
     twin_widget_t	    *next;
     twin_box_t		    *parent;
+    twin_widget_t	    *copy_geom;
     twin_bool_t		    paint;
     twin_bool_t		    layout;
     twin_bool_t		    want_focus;
     twin_argb32_t	    background;
     twin_rect_t		    extents;	/* current geometry */
-    twin_rect_t		    preferred;	/* desired geometry */
-    twin_stretch_t    	    hstretch;	/* stretch ratio in horizontal dir */
-    twin_stretch_t    	    vstretch;	/* stretch ratio in vertical dir */
+    twin_widget_layout_t    preferred;
     twin_dispatch_proc_t    dispatch;
 };
 
 struct _twin_box {
     twin_widget_t	widget;
-    twin_layout_t	layout;
+    twin_box_dir_t	dir;
     twin_widget_t	*children;
     twin_widget_t	*button_down;
     twin_widget_t	*focus;
@@ -421,15 +426,42 @@ typedef struct _twin_label {
     twin_point_t	offset;
 } twin_label_t;
 
-typedef void	(*twin_callback_t) (twin_widget_t *widget, void *closure);
+typedef enum _twin_button_signal {
+    TwinButtonSignalDown,   /* sent when button pressed */
+    TwinButtonSignalUp,	    /* send when button released inside widget */
+} twin_button_signal_t;
 
-typedef struct _twin_button {
-    twin_label_t	label;
-    twin_bool_t		pressed;
-    twin_bool_t		active;
-    twin_callback_t	callback;
-    void		*closure;
-} twin_button_t;
+typedef struct _twin_button twin_button_t;
+
+typedef void	(*twin_button_signal_proc_t) (twin_button_t	    *button,
+					      twin_button_signal_t  signal,
+					      void		    *closure);
+
+struct _twin_button {
+    twin_label_t		label;
+    twin_bool_t			pressed;
+    twin_bool_t			active;
+    twin_button_signal_proc_t	signal;
+    void			*closure;
+};
+
+typedef enum _twin_scroll_signal {
+    TwinScrollSignalUpArrow,
+    TwinScrollSignalDownArrow,
+    TwinScrollSignalThumb,
+    TwinScrollSignalAboveThumb,
+    TwinScrollSignalBelowThumb,
+} twin_scroll_signal_t;
+
+typedef struct _twin_scroll twin_scroll_t;
+
+typedef void	(*twin_scroll_signal_proc_t) (twin_scroll_t	    *scroll,
+					      twin_scroll_signal_t  signal,
+					      void		    *closure);
+
+struct _twin_scroll {
+    twin_widget_t		widget;
+};
 
 /*
  * twin_box.c
@@ -437,7 +469,7 @@ typedef struct _twin_button {
 
 twin_box_t *
 twin_box_create (twin_box_t	*parent,
-		 twin_layout_t	layout);
+		 twin_box_dir_t	dir);
 
 /*
  * twin_button.c
diff --git a/twin_box.c b/twin_box.c
index 85df058..9a1e043 100644
--- a/twin_box.c
+++ b/twin_box.c
@@ -28,58 +28,74 @@ void
 _twin_box_init (twin_box_t		*box,
 		twin_box_t		*parent,
 		twin_window_t		*window,
-		twin_layout_t		layout,
+		twin_box_dir_t		dir,
 		twin_dispatch_proc_t	dispatch)
 {
-    static twin_rect_t	preferred = { 0, 0, 0, 0 };
-    _twin_widget_init (&box->widget, parent, window, preferred, 0, 0, dispatch);
-    box->layout = layout;
-    box->children = 0;
+    static twin_widget_layout_t	preferred = { 0, 0, 0, 0 };
+    _twin_widget_init (&box->widget, parent, window, preferred, dispatch);
+    box->dir = dir;
+    box->children = NULL;
+    box->button_down = NULL;
+    box->focus = NULL;
 }
 
 static twin_dispatch_result_t
 _twin_box_query_geometry (twin_box_t *box)
 {
-    twin_widget_t   *widget;
-    twin_event_t    ev;
-    twin_coord_t    w, h;
-    twin_coord_t    c_w, c_h;
+    twin_widget_t	    *child;
+    twin_event_t	    ev;
+    twin_widget_layout_t    preferred;
 
-    w = 0; h = 0;
+    preferred.width = 0;
+    preferred.height = 0;
+    if (box->dir == TwinBoxHorz)
+    {
+	preferred.stretch_width = 0;
+	preferred.stretch_height = 10000;
+    }
+    else
+    {
+	preferred.stretch_width = 10000;
+	preferred.stretch_height = 0;
+    }
     /*
      * Find preferred geometry
      */
-    for (widget = box->children; widget; widget = widget->next)
+    for (child = box->children; child; child = child->next)
     {
-	ev.kind = TwinEventQueryGeometry;
-	(*widget->dispatch) (widget, &ev);
-	c_w = widget->preferred.right - widget->preferred.left;
-	c_h = widget->preferred.bottom - widget->preferred.top;
-	if (box->layout == TwinLayoutHorz)
+	if (child->layout)
+	{
+	    ev.kind = TwinEventQueryGeometry;
+	    (*child->dispatch) (child, &ev);
+	}
+	if (box->dir == TwinBoxHorz)
 	{
-	    w += c_w;
-	    if (c_h > h)
-		h = c_h;
+	    preferred.width += child->preferred.width;
+	    preferred.stretch_width += child->preferred.stretch_width;
+	    if (child->preferred.height > preferred.height)
+		preferred.height = child->preferred.height;
+	    if (child->preferred.stretch_height < preferred.stretch_height)
+		preferred.stretch_height = child->preferred.stretch_height;
 	}
 	else
 	{
-	    h += c_h;
-	    if (c_w > w)
-		w = c_w;
+	    preferred.height += child->preferred.height;
+	    preferred.stretch_height += child->preferred.stretch_height;
+	    if (child->preferred.width > preferred.width)
+		preferred.width = child->preferred.width;
+	    if (child->preferred.stretch_width < preferred.stretch_width)
+		preferred.stretch_width = child->preferred.stretch_width;
 	}
     }
-    box->widget.preferred.left = 0;
-    box->widget.preferred.top = 0;
-    box->widget.preferred.right = w;
-    box->widget.preferred.bottom = h;
-    return TwinDispatchNone;
+    box->widget.preferred = preferred;
+    return TwinDispatchContinue;
 }
 
 static twin_dispatch_result_t
 _twin_box_configure (twin_box_t *box)
 {
-    twin_coord_t    w = box->widget.extents.right - box->widget.extents.left;
-    twin_coord_t    h = box->widget.extents.bottom - box->widget.extents.top;
+    twin_coord_t    width = _twin_widget_width (box);
+    twin_coord_t    height = _twin_widget_height (box);
     twin_coord_t    actual;
     twin_coord_t    pref;
     twin_coord_t    delta;
@@ -87,21 +103,18 @@ _twin_box_configure (twin_box_t *box)
     twin_coord_t    stretch = 0;
     twin_coord_t    pos = 0;
     twin_widget_t   *child;
-    twin_dispatch_result_t  result = TwinDispatchNone;
     
-    if (box->layout == TwinLayoutHorz)
+    if (box->dir == TwinBoxHorz)
     {
-	for (child = box->children; child; child = child->next)
-	    stretch += child->hstretch;
-	actual = w;
-	pref = box->widget.preferred.right - box->widget.preferred.left;
+	stretch = box->widget.preferred.stretch_width;
+	actual = width;
+	pref = box->widget.preferred.width;
     }
     else
     {
-	for (child = box->children; child; child = child->next)
-	    stretch += child->vstretch;
-	actual = h;
-	pref = box->widget.preferred.bottom - box->widget.preferred.top;
+	stretch = box->widget.preferred.stretch_height;
+	actual = height;
+	pref = box->widget.preferred.height;
     }
     if (!stretch) stretch = 1;
     delta = delta_remain = actual - pref;
@@ -116,10 +129,10 @@ _twin_box_configure (twin_box_t *box)
 	    delta_this = delta_remain;
 	else
 	{
-	    if (box->layout == TwinLayoutHorz)
-		stretch_this = child->hstretch;
+	    if (box->dir == TwinBoxHorz)
+		stretch_this = child->preferred.stretch_width;
 	    else
-		stretch_this = child->vstretch;
+		stretch_this = child->preferred.stretch_height;
 	    delta_this = delta * stretch_this / stretch;
 	}
 	if (delta_remain < 0)
@@ -133,30 +146,33 @@ _twin_box_configure (twin_box_t *box)
 		delta_this = delta_remain;
 	}
 	delta_remain -= delta_this;
-	if (box->layout == TwinLayoutHorz)
+	if (box->dir == TwinBoxHorz)
 	{
-	    twin_coord_t    child_w = (child->preferred.right -
-				       child->preferred.left);
+	    twin_coord_t    child_w = child->preferred.width;
 	    extents.top = 0;
-	    extents.bottom = h;
+	    extents.bottom = height;
 	    extents.left = pos;
 	    pos = extents.right = pos + child_w + delta_this;
 	}
 	else
 	{
-	    twin_coord_t    child_h = (child->preferred.bottom -
-				       child->preferred.top);
+	    twin_coord_t    child_h = child->preferred.height;
 	    extents.left = 0;
-	    extents.right = w;
+	    extents.right = width;
 	    extents.top = pos;
 	    pos = extents.bottom = pos + child_h + delta_this;
 	}
-	ev.kind = TwinEventConfigure;
-	ev.u.configure.extents = extents;
-	(*child->dispatch) (child, &ev);
-	result = TwinDispatchPaint;
+	if (extents.left != ev.u.configure.extents.left ||
+	    extents.top != ev.u.configure.extents.top ||
+	    extents.right != ev.u.configure.extents.right ||
+	    extents.bottom != ev.u.configure.extents.bottom)
+	{
+	    ev.kind = TwinEventConfigure;
+	    ev.u.configure.extents = extents;
+	    (*child->dispatch) (child, &ev);
+	}
     }
-    return result;
+    return TwinDispatchContinue;
 }
 
 static twin_widget_t *
@@ -180,11 +196,12 @@ _twin_box_dispatch (twin_widget_t *widget, twin_event_t *event)
     twin_event_t    ev;
     twin_widget_t   *child;
 
+    if (_twin_widget_dispatch (widget, event) == TwinDispatchDone)
+	return TwinDispatchDone;
     switch (event->kind) {
     case TwinEventQueryGeometry:
 	return _twin_box_query_geometry (box);
     case TwinEventConfigure:
-	_twin_widget_dispatch (widget, event);
 	return _twin_box_configure (box);
     case TwinEventButtonDown:
 	box->button_down = _twin_box_xy_to_widget (box, 
@@ -227,17 +244,17 @@ _twin_box_dispatch (twin_widget_t *widget, twin_event_t *event)
     default:
 	break;
     }
-    return TwinDispatchNone;
+    return TwinDispatchContinue;
 }
 
 twin_box_t *
 twin_box_create (twin_box_t	*parent,
-		 twin_layout_t	layout)
+		 twin_box_dir_t	dir)
 {
     twin_box_t	*box = malloc (sizeof (twin_box_t));
     if (!box)
 	return 0;
-    _twin_box_init (box, parent, 0, layout, _twin_box_dispatch);
+    _twin_box_init (box, parent, 0, dir, _twin_box_dispatch);
     return box;
 }
 
diff --git a/twin_button.c b/twin_button.c
index a308abb..b340f10 100644
--- a/twin_button.c
+++ b/twin_button.c
@@ -52,16 +52,19 @@ _twin_button_dispatch (twin_widget_t *widget, twin_event_t *event)
 {
     twin_button_t    *button = (twin_button_t *) widget;
 
-    _twin_label_dispatch (widget, event);
+    if (_twin_label_dispatch (widget, event) == TwinDispatchDone)
+	return TwinDispatchDone;
     switch (event->kind) {
     case TwinEventPaint:
 	_twin_button_paint (button);
-	return TWIN_TRUE;
+	break;
     case TwinEventButtonDown:
 	button->pressed = TWIN_TRUE;
 	button->active = TWIN_TRUE;
 	_twin_button_set_label_offset (button);
-	return TWIN_TRUE;
+	if (button->signal)
+	    (*button->signal) (button, TwinButtonSignalDown, button->closure);
+	break;
     case TwinEventMotion:
 	if (button->pressed)
 	{
@@ -74,21 +77,21 @@ _twin_button_dispatch (twin_widget_t *widget, twin_event_t *event)
 		_twin_button_set_label_offset (button);
 	    }
 	}
-	return TWIN_TRUE;
+	break;
     case TwinEventButtonUp:
 	button->pressed = TWIN_FALSE;
 	if (button->active)
 	{
-	    if (button->callback)
-		(*button->callback) (&button->label.widget, button->closure);
 	    button->active = TWIN_FALSE;
 	    _twin_button_set_label_offset (button);
+	    if (button->signal)
+		(*button->signal) (button, TwinButtonSignalUp, button->closure);
 	}
-	return TWIN_TRUE;
+	break;
     default:
 	break;
     }
-    return TwinDispatchNone;
+    return TwinDispatchContinue;
 }
 
 void
@@ -103,6 +106,9 @@ _twin_button_init (twin_button_t	*button,
     _twin_label_init (&button->label, parent, value,
 		      foreground, font_size, font_style, dispatch);
     button->pressed = TWIN_FALSE;
+    button->active = TWIN_FALSE;
+    button->signal = NULL;
+    button->closure = NULL;
     _twin_button_set_label_offset (button);
 }
 
diff --git a/twin_calc.c b/twin_calc.c
new file mode 100644
index 0000000..56af91c
--- /dev/null
+++ b/twin_calc.c
@@ -0,0 +1,239 @@
+/*
+ * $Id$
+ *
+ * Copyright © 2004 Keith Packard
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of Keith Packard not be used in
+ * advertising or publicity pertaining to distribution of the software without
+ * specific, written prior permission.  Keith Packard makes no
+ * representations about the suitability of this software for any purpose.  It
+ * is provided "as is" without express or implied warranty.
+ *
+ * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "twin_calc.h"
+#include <stdio.h>
+
+#define TWIN_CALC_STACK	5
+#define TWIN_CALC_ZERO	    0
+#define TWIN_CALC_ONE	    1
+#define TWIN_CALC_TWO	    2
+#define TWIN_CALC_THREE	    3
+#define TWIN_CALC_FOUR	    4
+#define TWIN_CALC_FIVE	    5
+#define TWIN_CALC_SIX	    6
+#define TWIN_CALC_SEVEN	    7
+#define TWIN_CALC_EIGHT	    8
+#define TWIN_CALC_NINE	    9
+#define TWIN_CALC_PLUS	    10
+#define TWIN_CALC_MINUS	    11
+#define TWIN_CALC_TIMES	    12
+#define TWIN_CALC_DIVIDE    13
+#define TWIN_CALC_EQUAL	    14
+#define TWIN_CALC_CLEAR	    15
+#define TWIN_CALC_NBUTTON   16
+
+/*
+ * Layout:
+ *
+ *	    display
+ *
+ *     7  8  9 +
+ *     4  5  6 -
+ *     1  2  3 *
+ *     0 clr = ÷
+ */
+#define TWIN_CALC_COLS	4
+#define TWIN_CALC_ROWS	4
+
+const static int    calc_layout[TWIN_CALC_ROWS][TWIN_CALC_COLS] = {
+    { TWIN_CALC_SEVEN, TWIN_CALC_EIGHT, TWIN_CALC_NINE,  TWIN_CALC_PLUS },
+    { TWIN_CALC_FOUR,  TWIN_CALC_FIVE,  TWIN_CALC_SIX,   TWIN_CALC_MINUS },
+    { TWIN_CALC_ONE,   TWIN_CALC_TWO,   TWIN_CALC_THREE, TWIN_CALC_TIMES },
+    { TWIN_CALC_ZERO,  TWIN_CALC_CLEAR, TWIN_CALC_EQUAL, TWIN_CALC_DIVIDE },
+};
+
+typedef struct _twin_calc {
+    int    	    stack[TWIN_CALC_STACK];
+    int		    pending_op;
+    twin_bool_t	    pending_delete;
+    twin_window_t   *window;
+    twin_toplevel_t *toplevel;
+    twin_box_t	    *keys;
+    twin_box_t	    *cols[4];
+    twin_label_t    *display;
+    twin_button_t   *buttons[TWIN_CALC_NBUTTON];
+} twin_calc_t;
+
+static const char *twin_calc_labels[] = {
+    "0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
+    "+", "-", "*", "/", "=", "CLR"
+};
+
+#define TWIN_CALC_VALUE_SIZE	twin_int_to_fixed(24)
+#define TWIN_CALC_VALUE_STYLE	TWIN_TEXT_BOLD
+#define TWIN_CALC_VALUE_FG	0xff000000
+#define TWIN_CALC_VALUE_BG	0xc0c0c0c0
+#define TWIN_CALC_BUTTON_SIZE	twin_int_to_fixed(15)
+#define TWIN_CALC_BUTTON_STYLE	TWIN_TEXT_BOLD
+#define TWIN_CALC_BUTTON_FG	0xff000000
+#define TWIN_CALC_BUTTON_BG	0xc0808080
+
+static int
+_twin_calc_button_to_id (twin_calc_t *calc, twin_button_t *button)
+{
+    int	i;
+
+    for (i = 0; i < TWIN_CALC_NBUTTON; i++)
+	if (calc->buttons[i] == button)
+	    return i;
+    return -1;
+}
+
+static void
+_twin_calc_update_value (twin_calc_t *calc)
+{
+    char    v[20];
+
+    sprintf (v, "%d", calc->stack[0]);
+    twin_label_set (calc->display, v, TWIN_CALC_VALUE_FG,
+		    TWIN_CALC_VALUE_SIZE, TWIN_CALC_VALUE_STYLE);
+}
+
+static void
+_twin_calc_push (twin_calc_t *calc)
+{
+    int	i;
+
+    for (i = 0; i < TWIN_CALC_STACK - 1; i++)
+	calc->stack[i+1] = calc->stack[i];
+    calc->pending_delete = TWIN_TRUE;
+}
+
+static int
+_twin_calc_pop (twin_calc_t *calc)
+{
+    int i;
+    int	v = calc->stack[0];
+    for (i = 0; i < TWIN_CALC_STACK - 1; i++)
+	calc->stack[i] = calc->stack[i+1];
+    return v;
+}
+    
+static void
+_twin_calc_digit (twin_calc_t *calc, int digit)
+{
+    if (calc->pending_delete)
+    {
+	calc->stack[0] = 0;
+	calc->pending_delete = TWIN_FALSE;
+    }
+    calc->stack[0] = calc->stack[0] * 10 + digit;
+    _twin_calc_update_value (calc);
+}
+
+static void
+_twin_calc_button_signal (twin_button_t		*button,
+			  twin_button_signal_t	signal,
+			  void			*closure)
+{
+    twin_calc_t	*calc = closure;
+    int		i;
+    int		a, b;
+
+    if (signal != TwinButtonSignalDown) return;
+    i = _twin_calc_button_to_id (calc, button);
+    if (i < 0) return;
+    switch (i) {
+    case TWIN_CALC_PLUS:
+    case TWIN_CALC_MINUS:
+    case TWIN_CALC_TIMES:
+    case TWIN_CALC_DIVIDE:
+	calc->pending_op = i;
+	_twin_calc_push (calc);
+	break;
+    case TWIN_CALC_EQUAL:
+	if (calc->pending_op != 0)
+	{
+	    b = _twin_calc_pop (calc);
+	    a = _twin_calc_pop (calc);
+	    switch (calc->pending_op) {
+	    case TWIN_CALC_PLUS:    	a = a + b;  break;
+	    case TWIN_CALC_MINUS:    	a = a - b;  break;
+	    case TWIN_CALC_TIMES:    	a = a * b;  break;
+	    case TWIN_CALC_DIVIDE:    	if (!b) a = 0; else a = a / b; break;
+	    }
+	    _twin_calc_push (calc);
+	    calc->stack[0] = a;
+	    _twin_calc_update_value (calc);
+	    calc->pending_op = 0;
+	}
+        calc->pending_delete = TWIN_TRUE;
+	break;
+    case TWIN_CALC_CLEAR:
+	for (i = 0; i < TWIN_CALC_STACK; i++)
+	    calc->stack[i] = 0;
+        calc->pending_op = 0;
+        calc->pending_delete = TWIN_TRUE;
+	_twin_calc_update_value (calc);
+	break;
+    default:
+	_twin_calc_digit (calc, i);
+	break;
+    }
+}
+
+void
+twin_calc_start (twin_screen_t *screen, const char *name, int x, int y, int w, int h)
+{
+    twin_calc_t	*calc = malloc (sizeof (twin_calc_t));
+    int		i, j;
+
+    calc->toplevel = twin_toplevel_create (screen, 
+					   TWIN_ARGB32,
+					   TwinWindowApplication,
+					   x, y, w, h, name);
+    calc->display = twin_label_create (&calc->toplevel->box,
+				       "0",
+				       TWIN_CALC_VALUE_FG,
+				       TWIN_CALC_VALUE_SIZE,
+				       TWIN_CALC_VALUE_STYLE);
+    twin_widget_set (&calc->display->widget, TWIN_CALC_VALUE_BG);
+    calc->keys = twin_box_create (&calc->toplevel->box, TwinBoxHorz);
+    for (i = 0; i < TWIN_CALC_COLS; i++)
+    {
+	calc->cols[i] = twin_box_create (calc->keys, TwinBoxVert);
+	for (j = 0; j < TWIN_CALC_ROWS; j++)
+	{
+	    int	b = calc_layout[j][i];
+	    calc->buttons[b] = twin_button_create (calc->cols[i],
+						   twin_calc_labels[b],
+						   TWIN_CALC_BUTTON_FG,
+						   TWIN_CALC_BUTTON_SIZE,
+						   TWIN_CALC_BUTTON_STYLE);
+	    twin_widget_set (&calc->buttons[b]->label.widget,
+			     TWIN_CALC_BUTTON_BG);
+	    calc->buttons[b]->signal = _twin_calc_button_signal;
+	    calc->buttons[b]->closure = calc;
+	    if (i || j)
+		calc->buttons[b]->label.widget.copy_geom = &calc->buttons[calc_layout[0][0]]->label.widget;
+	}
+    }
+	    
+    for (i = 0; i < TWIN_CALC_STACK; i++)
+	calc->stack[i] = 0;
+    calc->pending_delete = TWIN_TRUE;
+    calc->pending_op = 0;
+    twin_toplevel_show (calc->toplevel);
+}
diff --git a/twin_calc.h b/twin_calc.h
new file mode 100644
index 0000000..0d3df7d
--- /dev/null
+++ b/twin_calc.h
@@ -0,0 +1,35 @@
+/*
+ * $Id$
+ *
+ * Copyright © 2004 Keith Packard
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of Keith Packard not be used in
+ * advertising or publicity pertaining to distribution of the software without
+ * specific, written prior permission.  Keith Packard makes no
+ * representations about the suitability of this software for any purpose.  It
+ * is provided "as is" without express or implied warranty.
+ *
+ * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <twin.h>
+
+#ifndef _TWIN_CALC_H_
+#define _TWIN_CALC_H_
+
+#include <twin.h>
+
+void
+twin_calc_start (twin_screen_t *screen, const char *name, int x, int y, int w, int h);
+
+#endif /* _TWIN_CALC_H_ */
diff --git a/twin_label.c b/twin_label.c
index 6d013ee..6d74160 100644
--- a/twin_label.c
+++ b/twin_label.c
@@ -30,16 +30,14 @@ _twin_label_query_geometry (twin_label_t *label)
     twin_path_t		*path = twin_path_create ();
     twin_text_metrics_t	m;
     
-    label->widget.preferred.left = 0;
-    label->widget.preferred.top = 0;
-    label->widget.preferred.right = twin_fixed_to_int (label->font_size);
-    label->widget.preferred.bottom = twin_fixed_to_int (label->font_size) * 2;
+    label->widget.preferred.width = twin_fixed_to_int (label->font_size) * 2;
+    label->widget.preferred.height = twin_fixed_to_int (label->font_size) * 2;
     if (path)
     {
 	twin_path_set_font_size (path, label->font_size);
 	twin_path_set_font_style (path, label->font_style);
 	twin_text_metrics_utf8 (path, label->label, &m);
-	label->widget.preferred.right += twin_fixed_to_int (m.width);
+	label->widget.preferred.width += twin_fixed_to_int (m.width);
 	twin_path_destroy (path);
     }
 }
@@ -74,18 +72,19 @@ _twin_label_dispatch (twin_widget_t *widget, twin_event_t *event)
 {
     twin_label_t    *label = (twin_label_t *) widget;
 
-    _twin_widget_dispatch (widget, event);
+    if (_twin_widget_dispatch (widget, event) == TwinDispatchDone)
+	return TwinDispatchDone;
     switch (event->kind) {
     case TwinEventPaint:
 	_twin_label_paint (label);
-	return TwinDispatchNone;
+	break;
     case TwinEventQueryGeometry:
 	_twin_label_query_geometry (label);
 	break;
     default:
 	break;
     }
-    return TwinDispatchNone;
+    return TwinDispatchContinue;
 }
 
 void
@@ -122,9 +121,8 @@ _twin_label_init (twin_label_t		*label,
 		  twin_style_t		font_style,
 		  twin_dispatch_proc_t	dispatch)
 {
-    static const twin_rect_t	empty = { 0, 0, 0, 0 };
-    _twin_widget_init (&label->widget, parent, 0, 
-		       empty, 1, 1, dispatch);
+    static const twin_widget_layout_t	preferred = { 0, 0, 1, 1 };
+    _twin_widget_init (&label->widget, parent, 0, preferred, dispatch);
     label->label = NULL;
     label->offset.x = 0;
     label->offset.y = 0;
diff --git a/twin_toplevel.c b/twin_toplevel.c
index 5527a1e..42de014 100644
--- a/twin_toplevel.c
+++ b/twin_toplevel.c
@@ -91,7 +91,7 @@ _twin_toplevel_init (twin_toplevel_t	    *toplevel,
     window->destroy = _twin_toplevel_destroy;
     window->event = _twin_toplevel_event;
     window->client_data = toplevel;
-    _twin_box_init (&toplevel->box, 0, window, TwinLayoutVert, dispatch);
+    _twin_box_init (&toplevel->box, 0, window, TwinBoxVert, dispatch);
 }
 
 twin_toplevel_t *
diff --git a/twin_widget.c b/twin_widget.c
index cc0e12a..c9b0ed9 100644
--- a/twin_widget.c
+++ b/twin_widget.c
@@ -41,9 +41,19 @@ twin_dispatch_result_t
 _twin_widget_dispatch (twin_widget_t *widget, twin_event_t *event)
 {
     switch (event->kind) {
+    case TwinEventQueryGeometry:
+	widget->layout = TWIN_FALSE;
+	if (widget->copy_geom)
+	{
+	    twin_widget_t   *copy = widget->copy_geom;
+	    if (copy->layout)
+		(*copy->dispatch) (copy, event);
+	    widget->preferred = copy->preferred;
+	    return TwinDispatchDone;
+	}
+	break;
     case TwinEventConfigure:
 	widget->extents = event->u.configure.extents;
-	widget->layout = TWIN_FALSE;
 	break;
     case TwinEventPaint:
 	_twin_widget_paint (widget);
@@ -52,16 +62,14 @@ _twin_widget_dispatch (twin_widget_t *widget, twin_event_t *event)
     default:
 	break;
     }
-    return TwinDispatchNone;
+    return TwinDispatchContinue;
 }
 
 void
 _twin_widget_init (twin_widget_t	*widget,
 		   twin_box_t		*parent,
 		   twin_window_t	*window,
-		   twin_rect_t		preferred,
-		   twin_stretch_t	hstretch,
-		   twin_stretch_t	vstretch,
+		   twin_widget_layout_t	preferred,
 		   twin_dispatch_proc_t	dispatch)
 {
     if (parent)
@@ -77,13 +85,15 @@ _twin_widget_init (twin_widget_t	*widget,
 	widget->next = NULL;
     widget->window = window;
     widget->parent = parent;
+    widget->copy_geom = NULL;
     widget->paint = TWIN_TRUE;
+    widget->layout = TWIN_TRUE;
+    widget->want_focus = TWIN_FALSE;
+    widget->background = 0x00000000;
+    widget->extents.left = widget->extents.top = 0;
+    widget->extents.right = widget->extents.bottom = 0;
     widget->preferred = preferred;
-    widget->extents = preferred;
-    widget->hstretch = hstretch;
-    widget->vstretch = vstretch;
     widget->dispatch = dispatch;
-    widget->background = 0x00000000;
 }
 
 void
@@ -171,20 +181,19 @@ twin_widget_create (twin_box_t	    *parent,
 		    twin_argb32_t   background,
 		    twin_coord_t    width,
 		    twin_coord_t    height,
-		    twin_stretch_t  hstretch,
-		    twin_stretch_t  vstretch)
+		    twin_stretch_t  stretch_width,
+		    twin_stretch_t  stretch_height)
 {
-    twin_widget_t   *widget = malloc (sizeof (twin_widget_t));
-    twin_rect_t	    extents;
+    twin_widget_t	    *widget = malloc (sizeof (twin_widget_t));
+    twin_widget_layout_t    preferred;
 
     if (!widget)
 	return NULL;
-    extents.left = 0;
-    extents.top = 0;
-    extents.right = width;
-    extents.bottom = height;
-    _twin_widget_init (widget, parent, 0, extents, hstretch, vstretch, 
-		       _twin_widget_dispatch);
+    preferred.width = width;
+    preferred.height = height;
+    preferred.stretch_width = stretch_width;
+    preferred.stretch_height = stretch_height;
+    _twin_widget_init (widget, parent, 0, preferred, _twin_widget_dispatch);
     widget->background = background;
     return widget;
 }
diff --git a/twinint.h b/twinint.h
index 4063948..c970d0b 100644
--- a/twinint.h
+++ b/twinint.h
@@ -455,7 +455,7 @@ void
 _twin_box_init (twin_box_t		*box,
 		twin_box_t		*parent,
 		twin_window_t		*window,
-		twin_layout_t		layout,
+		twin_box_dir_t		dir,
 		twin_dispatch_proc_t	dispatch);
 
 twin_dispatch_result_t
@@ -465,9 +465,7 @@ void
 _twin_widget_init (twin_widget_t	*widget,
 		   twin_box_t		*parent,
 		   twin_window_t	*window,
-		   twin_rect_t		preferred,
-		   twin_stretch_t	hstretch,
-		   twin_stretch_t	vstretch,
+		   twin_widget_layout_t	preferred,
 		   twin_dispatch_proc_t	dispatch);
 
 twin_dispatch_result_t
diff --git a/xtwin.c b/xtwin.c
index 5a544d4..e656019 100644
--- a/xtwin.c
+++ b/xtwin.c
@@ -33,6 +33,7 @@
 #include <twin_text.h>
 #include <twin_demo.h>
 #include <twin_hello.h>
+#include <twin_calc.h>
 
 #define WIDTH	512
 #define HEIGHT	512
@@ -49,9 +50,11 @@ main (int argc, char **argv)
     twin_clock_start (x11->screen, "Clock", 10, 10, 200, 200);
     twin_text_start (x11->screen,  "Gettysburg Address",
 		     0, 0, 300, 300);
-#endif
     twin_hello_start (x11->screen, "Hello, World",
 		      0, 0, 200, 200);
+#endif
+    twin_calc_start (x11->screen, "Calculator",
+		     100, 100, 200, 200);
     twin_dispatch ();
     return 0;
 }