[gtk+] scrolledwindow: Bug 766569 - General size request fixes.

[Tristan Van Berkom <tvb src gnome org>]

commit d7e242eec03a1056cdc0808aef6bcf1002b4df8b
Author: Tristan Van Berkom <tristan vanberkom codethink co uk>
Date:   Tue Jun 7 14:04:42 2016 +0900

    scrolledwindow: Bug 766569 - General size request fixes.
    
    This patch does a couple of things:
    
      o Removes the obscure 'extra_width' and 'extra_height' variables
        making the request code exceedingly difficult to read
    
      o Fixes the max-content-size properties introduced in bug 742281
        so that they do not grow the minimum request.
    
      o Cleanup of request code in general:
        - min/max content sizes are clamped around the child request as needed
        - scrollbar requests are only added in one place, after child request
          sizes are calculated and without the extra_width/height thing.

 gtk/gtkscrolledwindow.c |  110 ++++++++++++++++-------------------------------
 1 files changed, 37 insertions(+), 73 deletions(-)
---
diff --git a/gtk/gtkscrolledwindow.c b/gtk/gtkscrolledwindow.c
index 262546b..a3a89b6 100644
--- a/gtk/gtkscrolledwindow.c
+++ b/gtk/gtkscrolledwindow.c
@@ -1756,20 +1756,16 @@ gtk_scrolled_window_measure (GtkCssGadget   *gadget,
   GtkScrolledWindow *scrolled_window = GTK_SCROLLED_WINDOW (widget);
   GtkScrolledWindowPrivate *priv = scrolled_window->priv;
   GtkBin *bin = GTK_BIN (scrolled_window);
-  gint extra_width;
-  gint extra_height;
   gint scrollbar_spacing;
   GtkRequisition hscrollbar_requisition;
   GtkRequisition vscrollbar_requisition;
   GtkRequisition minimum_req, natural_req;
   GtkWidget *child;
   gint min_child_size, nat_child_size;
-  GtkBorder border = { 0 };
+  GtkBorder sborder = { 0 };
 
   scrollbar_spacing = _gtk_scrolled_window_get_scrollbar_spacing (scrolled_window);
 
-  extra_width = 0;
-  extra_height = 0;
   minimum_req.width = 0;
   minimum_req.height = 0;
   natural_req.width = 0;
@@ -1783,8 +1779,11 @@ gtk_scrolled_window_measure (GtkCssGadget   *gadget,
   child = gtk_bin_get_child (bin);
 
   if (GTK_IS_SCROLLABLE (child))
-    gtk_scrollable_get_border (GTK_SCROLLABLE (child), &border);
+    gtk_scrollable_get_border (GTK_SCROLLABLE (child), &sborder);
 
+  /*
+   * First collect the child requisition
+   */
   if (child && gtk_widget_get_visible (child))
     {
       if (orientation == GTK_ORIENTATION_HORIZONTAL)
@@ -1793,39 +1792,19 @@ gtk_scrolled_window_measure (GtkCssGadget   *gadget,
                                           &min_child_size,
                                           &nat_child_size);
 
+         natural_req.width += nat_child_size;
+
          if (priv->hscrollbar_policy == GTK_POLICY_NEVER)
            {
              minimum_req.width += min_child_size;
-             natural_req.width += nat_child_size;
            }
          else
            {
-             if (priv->min_content_width >= 0)
-               {
-                 minimum_req.width += priv->min_content_width;
-                 natural_req.width += priv->min_content_width;
-                 extra_width = -1;
-               }
+             gint min = priv->min_content_width >= 0 ? priv->min_content_width : 0;
+             gint max = priv->max_content_width >= 0 ? priv->max_content_width : G_MAXINT;
 
-              if (priv->max_content_width > -1 &&
-                  priv->max_content_width > natural_req.width &&
-                  nat_child_size > natural_req.width)
-                {
-                  gint width = MIN (priv->max_content_width, min_child_size);
-
-                  /* The maximum content width must respect the minimum content width.
-                   * It'll grow at least until min_content_width, and at most until
-                   * max_content_width.
-                  */
-                  minimum_req.width = MAX (minimum_req.width, width);
-                  natural_req.width = MAX (natural_req.width, width);
-                }
-
-             if (policy_may_be_visible (priv->vscrollbar_policy) && !priv->use_indicators)
-               {
-                 minimum_req.width += vscrollbar_requisition.width;
-                 natural_req.width += vscrollbar_requisition.width;
-               }
+             minimum_req.width = CLAMP (minimum_req.width, min, max);
+             natural_req.width = CLAMP (natural_req.width, min, max);
            }
        }
       else /* GTK_ORIENTATION_VERTICAL */
@@ -1834,65 +1813,50 @@ gtk_scrolled_window_measure (GtkCssGadget   *gadget,
                                            &min_child_size,
                                            &nat_child_size);
 
+         natural_req.height += nat_child_size;
+
          if (priv->vscrollbar_policy == GTK_POLICY_NEVER)
            {
              minimum_req.height += min_child_size;
-             natural_req.height += nat_child_size;
            }
          else
            {
-             if (priv->min_content_height >= 0)
-               {
-                 minimum_req.height += priv->min_content_height;
-                 natural_req.height += priv->min_content_height;
-                 extra_height = -1;
-               }
+             gint min = priv->min_content_height >= 0 ? priv->min_content_height : 0;
+             gint max = priv->max_content_height >= 0 ? priv->max_content_height : G_MAXINT;
 
-              if (priv->max_content_height > -1 &&
-                  priv->max_content_height > natural_req.height &&
-                  nat_child_size > natural_req.height)
-                {
-                  gint height = MIN (priv->max_content_height, min_child_size);
-
-                  /* The maximum content height must respect the minimum content height.
-                   * It'll grow at least until min_content_height, and at most until
-                   * max_content_height.
-                   */
-                  minimum_req.height = MAX (minimum_req.height, height);
-                  natural_req.height = MAX (natural_req.height, height);
-                }
-
-             if (policy_may_be_visible (priv->hscrollbar_policy) && !priv->use_indicators)
-               {
-                 minimum_req.height += hscrollbar_requisition.height;
-                 natural_req.height += hscrollbar_requisition.height;
-               }
+             minimum_req.height = CLAMP (minimum_req.height, min, max);
+             natural_req.height = CLAMP (natural_req.height, min, max);
            }
        }
     }
 
+  /*
+   * Now add to the requisition any additional space for surrounding scrollbars
+   * and the special scrollable border.
+   */
   if (policy_may_be_visible (priv->hscrollbar_policy))
     {
-      minimum_req.width = MAX (minimum_req.width, hscrollbar_requisition.width + border.left + border.right);
-      natural_req.width = MAX (natural_req.width, hscrollbar_requisition.width + border.left + border.right);
-      if (!priv->use_indicators &&
-          (!extra_height || priv->hscrollbar_policy == GTK_POLICY_ALWAYS))
-       extra_height = scrollbar_spacing + hscrollbar_requisition.height;
+      minimum_req.width = MAX (minimum_req.width, hscrollbar_requisition.width + sborder.left + 
sborder.right);
+      natural_req.width = MAX (natural_req.width, hscrollbar_requisition.width + sborder.left + 
sborder.right);
+
+      if (!priv->use_indicators)
+       {
+         minimum_req.height += scrollbar_spacing + hscrollbar_requisition.height;
+         natural_req.height += scrollbar_spacing + hscrollbar_requisition.height;
+       }
     }
 
   if (policy_may_be_visible (priv->vscrollbar_policy))
     {
-      minimum_req.height = MAX (minimum_req.height, vscrollbar_requisition.height + border.top + 
border.bottom);
-      natural_req.height = MAX (natural_req.height, vscrollbar_requisition.height + border.top + 
border.bottom);
-      if (!priv->use_indicators &&
-          (!extra_width || priv->vscrollbar_policy == GTK_POLICY_ALWAYS))
-       extra_width = scrollbar_spacing + vscrollbar_requisition.width;
-    }
+      minimum_req.height = MAX (minimum_req.height, vscrollbar_requisition.height + sborder.top + 
sborder.bottom);
+      natural_req.height = MAX (natural_req.height, vscrollbar_requisition.height + sborder.top + 
sborder.bottom);
 
-  minimum_req.width  += MAX (0, extra_width);
-  minimum_req.height += MAX (0, extra_height);
-  natural_req.width  += MAX (0, extra_width);
-  natural_req.height += MAX (0, extra_height);
+      if (!priv->use_indicators)
+       {
+         minimum_req.width += scrollbar_spacing + vscrollbar_requisition.width;
+         natural_req.width += scrollbar_spacing + vscrollbar_requisition.width;
+       }
+    }
 
   if (orientation == GTK_ORIENTATION_HORIZONTAL)
     {