[gtk+] GtkScrolledWindow: Bug 766569 - Make propagation of natural child sizes optional

[Matthias Clasen <matthiasc src gnome org>]

commit 0984d1622d022bf67207f985f7842b6299818e20
Author: Tristan Van Berkom <tristan vanberkom codethink co uk>
Date:   Wed Aug 31 13:54:25 2016 +0900

    GtkScrolledWindow: Bug 766569 - Make propagation of natural child sizes optional
    
    Making propagation of child natural sizes mandatory (or default, even) was
    evidently a mistake as this causes dynamic content in a scrolled window
    to resize it's parent when the scrolled window is competing for space
    with an adjacent widget.
    
    This patch instead adds API to control whether natural width and
    height of the child should be propagated through the scrolled windows
    size requests.

 docs/reference/gtk/gtk3-sections.txt |    4 +
 gtk/gtkscrolledwindow.c              |  178 ++++++++++++++++++++++++++++++++--
 gtk/gtkscrolledwindow.h              |   12 +++
 3 files changed, 184 insertions(+), 10 deletions(-)
---
diff --git a/docs/reference/gtk/gtk3-sections.txt b/docs/reference/gtk/gtk3-sections.txt
index 98641e2..e6a4147 100644
--- a/docs/reference/gtk/gtk3-sections.txt
+++ b/docs/reference/gtk/gtk3-sections.txt
@@ -3239,6 +3239,10 @@ gtk_scrolled_window_set_capture_button_press
 gtk_scrolled_window_get_capture_button_press
 gtk_scrolled_window_set_overlay_scrolling
 gtk_scrolled_window_get_overlay_scrolling
+gtk_scrolled_window_set_propagate_natural_width
+gtk_scrolled_window_get_propagate_natural_width
+gtk_scrolled_window_set_propagate_natural_height
+gtk_scrolled_window_get_propagate_natural_height
 
 <SUBSECTION Standard>
 GTK_SCROLLED_WINDOW
diff --git a/gtk/gtkscrolledwindow.c b/gtk/gtkscrolledwindow.c
index 082a0dc..b974987 100644
--- a/gtk/gtkscrolledwindow.c
+++ b/gtk/gtkscrolledwindow.c
@@ -233,14 +233,16 @@ struct _GtkScrolledWindowPrivate
   GtkCornerType  window_placement;
   guint16  shadow_type;
 
-  guint    hscrollbar_policy      : 2;
-  guint    vscrollbar_policy      : 2;
-  guint    hscrollbar_visible     : 1;
-  guint    vscrollbar_visible     : 1;
-  guint    focus_out              : 1; /* used by ::move-focus-out implementation */
-  guint    overlay_scrolling      : 1;
-  guint    use_indicators         : 1;
-  guint    auto_added_viewport    : 1;
+  guint    hscrollbar_policy        : 2;
+  guint    vscrollbar_policy        : 2;
+  guint    hscrollbar_visible       : 1;
+  guint    vscrollbar_visible       : 1;
+  guint    focus_out                : 1; /* used by ::move-focus-out implementation */
+  guint    overlay_scrolling        : 1;
+  guint    use_indicators           : 1;
+  guint    auto_added_viewport      : 1;
+  guint    propagate_natural_width  : 1;
+  guint    propagate_natural_height : 1;
 
   gint     min_content_width;
   gint     min_content_height;
@@ -303,6 +305,8 @@ enum {
   PROP_OVERLAY_SCROLLING,
   PROP_MAX_CONTENT_WIDTH,
   PROP_MAX_CONTENT_HEIGHT,
+  PROP_PROPAGATE_NATURAL_WIDTH,
+  PROP_PROPAGATE_NATURAL_HEIGHT,
   NUM_PROPERTIES
 };
 
@@ -739,6 +743,42 @@ gtk_scrolled_window_class_init (GtkScrolledWindowClass *class)
                         -1, G_MAXINT, -1,
                         GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY);
 
+  /**
+   * GtkScrolledWindow:propagate-natural-width:
+   *
+   * Whether the natural width of the child should be calculated and propagated
+   * through the scrolled windows requested natural width.
+   *
+   * This is useful in cases where an attempt should be made to allocate exactly
+   * enough space for the natural size of the child.
+   *
+   * Since: 3.22
+   */
+  properties[PROP_PROPAGATE_NATURAL_WIDTH] =
+      g_param_spec_boolean ("propagate-natural-width",
+                            P_("Propagate Natural Width"),
+                            P_("Propagate Natural Width"),
+                            FALSE,
+                            GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY);
+
+  /**
+   * GtkScrolledWindow:propagate-natural-height:
+   *
+   * Whether the natural height of the child should be calculated and propagated
+   * through the scrolled windows requested natural height.
+   *
+   * This is useful in cases where an attempt should be made to allocate exactly
+   * enough space for the natural size of the child.
+   *
+   * Since: 3.22
+   */
+  properties[PROP_PROPAGATE_NATURAL_HEIGHT] =
+      g_param_spec_boolean ("propagate-natural-height",
+                            P_("Propagate Natural Height"),
+                            P_("Propagate Natural Height"),
+                            FALSE,
+                            GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY);
+
   g_object_class_install_properties (gobject_class, NUM_PROPERTIES, properties);
 
   /**
@@ -1798,7 +1838,8 @@ gtk_scrolled_window_measure (GtkCssGadget   *gadget,
                                           &min_child_size,
                                           &nat_child_size);
 
-         natural_req.width += nat_child_size;
+         if (priv->propagate_natural_width)
+           natural_req.width += nat_child_size;
 
          if (priv->hscrollbar_policy == GTK_POLICY_NEVER)
            {
@@ -1819,7 +1860,8 @@ gtk_scrolled_window_measure (GtkCssGadget   *gadget,
                                            &min_child_size,
                                            &nat_child_size);
 
-         natural_req.height += nat_child_size;
+         if (priv->propagate_natural_height)
+           natural_req.height += nat_child_size;
 
          if (priv->vscrollbar_policy == GTK_POLICY_NEVER)
            {
@@ -1836,6 +1878,10 @@ gtk_scrolled_window_measure (GtkCssGadget   *gadget,
        }
     }
 
+  /* Ensure we make requests with natural size >= minimum size */
+  natural_req.height = MAX (minimum_req.height, natural_req.height);
+  natural_req.width  = MAX (minimum_req.width,  natural_req.width);
+
   /*
    * Now add to the requisition any additional space for surrounding scrollbars
    * and the special scrollable border.
@@ -2847,6 +2893,14 @@ gtk_scrolled_window_set_property (GObject      *object,
       gtk_scrolled_window_set_max_content_height (scrolled_window,
                                                   g_value_get_int (value));
       break;
+    case PROP_PROPAGATE_NATURAL_WIDTH:
+      gtk_scrolled_window_set_propagate_natural_width (scrolled_window,
+                                                      g_value_get_boolean (value));
+      break;
+    case PROP_PROPAGATE_NATURAL_HEIGHT:
+      gtk_scrolled_window_set_propagate_natural_height (scrolled_window,
+                                                      g_value_get_boolean (value));
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -2905,6 +2959,12 @@ gtk_scrolled_window_get_property (GObject    *object,
     case PROP_MAX_CONTENT_HEIGHT:
       g_value_set_int (value, priv->max_content_height);
       break;
+    case PROP_PROPAGATE_NATURAL_WIDTH:
+      g_value_set_boolean (value, priv->propagate_natural_width);
+      break;
+    case PROP_PROPAGATE_NATURAL_HEIGHT:
+      g_value_set_boolean (value, priv->propagate_natural_height);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -4731,3 +4791,101 @@ gtk_scrolled_window_get_max_content_height (GtkScrolledWindow *scrolled_window)
 
   return scrolled_window->priv->max_content_height;
 }
+
+/**
+ * gtk_scrolled_window_set_propagate_natural_width:
+ * @scrolled_window: a #GtkScrolledWindow
+ * @propagate: whether to propagate natural width
+ *
+ * Sets whether the natural width of the child should be calculated and propagated
+ * through the scrolled windows requested natural width.
+ *
+ * Since: 3.22
+ */
+void
+gtk_scrolled_window_set_propagate_natural_width (GtkScrolledWindow *scrolled_window,
+                                                gboolean           propagate)
+{
+  GtkScrolledWindowPrivate *priv;
+
+  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));
+
+  priv = scrolled_window->priv;
+
+  propagate = !!propagate;
+
+  if (priv->propagate_natural_width != propagate)
+    {
+      priv->propagate_natural_width = propagate;
+      g_object_notify_by_pspec (G_OBJECT (scrolled_window), properties [PROP_PROPAGATE_NATURAL_WIDTH]);
+      gtk_widget_queue_resize (GTK_WIDGET (scrolled_window));
+    }
+}
+
+/**
+ * gtk_scrolled_window_get_propagate_natural_width:
+ * @scrolled_window: a #GtkScrolledWindow
+ *
+ * Reports whether the natural width of the child will be calculated and propagated
+ * through the scrolled windows requested natural width.
+ *
+ * Returns: whether natural width propagation is enabled.
+ *
+ * Since: 3.22
+ */
+gint
+gtk_scrolled_window_get_propagate_natural_width (GtkScrolledWindow *scrolled_window)
+{
+  g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), -1);
+
+  return scrolled_window->priv->propagate_natural_width;
+}
+
+/**
+ * gtk_scrolled_window_set_propagate_natural_height:
+ * @scrolled_window: a #GtkScrolledWindow
+ * @propagate: whether to propagate natural height
+ *
+ * Sets whether the natural height of the child should be calculated and propagated
+ * through the scrolled windows requested natural height.
+ *
+ * Since: 3.22
+ */
+void
+gtk_scrolled_window_set_propagate_natural_height (GtkScrolledWindow *scrolled_window,
+                                                gboolean           propagate)
+{
+  GtkScrolledWindowPrivate *priv;
+
+  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));
+
+  priv = scrolled_window->priv;
+
+  propagate = !!propagate;
+
+  if (priv->propagate_natural_height != propagate)
+    {
+      priv->propagate_natural_height = propagate;
+      g_object_notify_by_pspec (G_OBJECT (scrolled_window), properties [PROP_PROPAGATE_NATURAL_HEIGHT]);
+      gtk_widget_queue_resize (GTK_WIDGET (scrolled_window));
+    }
+}
+
+/**
+ * gtk_scrolled_window_get_propagate_natural_height:
+ * @scrolled_window: a #GtkScrolledWindow
+ *
+ * Reports whether the natural height of the child will be calculated and propagated
+ * through the scrolled windows requested natural height.
+ *
+ * Returns: whether natural height propagation is enabled.
+ *
+ * Since: 3.22
+ */
+gint
+gtk_scrolled_window_get_propagate_natural_height (GtkScrolledWindow *scrolled_window)
+{
+  g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), -1);
+
+  return scrolled_window->priv->propagate_natural_height;
+}
diff --git a/gtk/gtkscrolledwindow.h b/gtk/gtkscrolledwindow.h
index 0aca3ad..1b8d5cd 100644
--- a/gtk/gtkscrolledwindow.h
+++ b/gtk/gtkscrolledwindow.h
@@ -226,6 +226,18 @@ void           gtk_scrolled_window_set_max_content_height (GtkScrolledWindow *sc
 GDK_AVAILABLE_IN_3_22
 gint           gtk_scrolled_window_get_max_content_height (GtkScrolledWindow *scrolled_window);
 
+GDK_AVAILABLE_IN_3_22
+void           gtk_scrolled_window_set_propagate_natural_width  (GtkScrolledWindow *scrolled_window,
+                                                                gboolean           propagate);
+GDK_AVAILABLE_IN_3_22
+gboolean       gtk_scrolled_window_get_propagate_natural_width  (GtkScrolledWindow *scrolled_window);
+
+GDK_AVAILABLE_IN_3_22
+void           gtk_scrolled_window_set_propagate_natural_height (GtkScrolledWindow *scrolled_window,
+                                                                gboolean           propagate);
+GDK_AVAILABLE_IN_3_22
+gboolean       gtk_scrolled_window_get_propagate_natural_height (GtkScrolledWindow *scrolled_window);
+
 G_END_DECLS