Merge branch 'wip/otte/for-master' into 'master'

Wip/otte/for master

Closes #3137

See merge request GNOME/gtk!2550

2 files changed, 60 insertions, 16 deletions

diff --git a/gtk/gtkrevealer.c b/gtk/gtkrevealer.c
index ccaaef4143..34d538d03f 100644
--- a/gtk/gtkrevealer.c
+++ b/gtk/gtkrevealer.c
@@ -457,8 +457,6 @@ gtk_revealer_size_allocate (GtkWidget *widget,
       return;
     }
 
-  child_width = width;
-  child_height = height;
   hscale = get_child_size_scale (revealer, GTK_ORIENTATION_HORIZONTAL);
   vscale = get_child_size_scale (revealer, GTK_ORIENTATION_VERTICAL);
   if (hscale <= 0 || vscale <= 0)
@@ -475,29 +473,53 @@ gtk_revealer_size_allocate (GtkWidget *widget,
    * some other form of clipping. We do this by reverse-applying
    * the scale when size allocating the child.
    *
-   * Unfortunately this causes precision issues, because the scaled
-   * size request is always rounded up to an integer.  For instance if
-   * natural with is 100, and scale is 0.001.  we will request a
-   * natural size of ceil(0.1) == 1, but reversing this results in 1 /
-   * 0.001 == 1000 (rather than 100). In the swing case we can get the
-   * scale arbitrarily near 0 causing arbitrary large problems here.
+   * Unfortunately this causes precision issues.
    *
-   * In order to avoid such issue we pick an arbitrary maximum upscale
-   * scale factor of 100. This means that in the case where the allocated
-   * size is 1 we never allocate the child at > 100 px. This means
-   * that in large downscaling cases we may run into the clipping issue
-   * described above. However, at these downscaling levels (100 times!)
-   * we're unlikely to notice much detail anyway.
+   * So we assume that the fully expanded revealer will likely get
+   * an allocation that matches the child's minimum or natural allocation,
+   * so we special-case these two values.
+   * So when - due to the precision loss - multiple sizes would match
+   * the current allocation, we don't pick one at random, we prefer the
+   * min and nat size.
+   *
+   * On top, the scaled size request is always rounded up to an integer.
+   * For instance if natural with is 100, and scale is 0.001, we would
+   * request a natural size of ceil(0.1) == 1, but reversing this would
+   * result in 1 / 0.001 == 1000 (rather than 100).
+   * In the swing case we can get the scale arbitrarily near 0 causing
+   * arbitrary large problems.
+   * These also get avoided by the preference.
    */
 
   if (hscale < 1.0)
     {
+      int min, nat;
       g_assert (vscale == 1.0);
-      child_width = MIN (100*width, ceil (width / hscale));
+      gtk_widget_measure (priv->child, GTK_ORIENTATION_HORIZONTAL, height, &min, &nat, NULL, NULL);
+      if (ceil (nat * hscale) == width)
+        child_width = nat;
+      else if (ceil (min * hscale) == width)
+        child_width = min;
+      else
+        child_width = floor (width / hscale);
+      child_height = height;
     }
   else if (vscale < 1.0)
     {
-      child_height = MIN (100*height, ceil (height / vscale));
+      int min, nat;
+      child_width = width;
+      gtk_widget_measure (priv->child, GTK_ORIENTATION_VERTICAL, width, &min, &nat, NULL, NULL);
+      if (ceil (nat * vscale) == height)
+        child_height = nat;
+      else if (ceil (min * vscale) == height)
+        child_height = min;
+      else
+        child_height = floor (height / vscale);
+    }
+  else
+    {
+      child_width = width;
+      child_height = height;
     }
 
   transform = NULL;
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 18038fd1a4..01ea24da59 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -3785,6 +3785,28 @@ gtk_widget_allocate (GtkWidget    *widget,
                  "How does the code know the size to allocate?",
                  gtk_widget_get_name (widget), widget);
     }
+  if (!GTK_IS_SCROLLABLE (widget))
+    {
+      int min;
+      gtk_widget_measure (widget, GTK_ORIENTATION_VERTICAL, width, &min, NULL, NULL, NULL);
+      if (min > height)
+        {
+          g_critical ("Allocation height too small. Tried to allocate %dx%d, but %s %p needs "
+                      "at least %dx%d.",
+                      width, height,
+                      gtk_widget_get_name (widget), widget,
+                      width, min);
+        }
+      gtk_widget_measure (widget, GTK_ORIENTATION_HORIZONTAL, height, &min, NULL, NULL, NULL);
+      if (min > width)
+        {
+          g_critical ("Allocation width too small. Tried to allocate %dx%d, but %s %p needs "
+                      "at least %dx%d.",
+                      width, height,
+                      gtk_widget_get_name (widget), widget,
+                      min, height);
+        }
+    }
 #endif /* G_ENABLE_DEBUG */
 
   alloc_needed = priv->alloc_needed;