From b8468af4117974fd2af14e863865f494b021f29c Mon Sep 17 00:00:00 2001
From: Benjamin Otte <otte@redhat.com>
Date: Tue, 7 Dec 2021 21:54:02 +0100
Subject: [PATCH] viewport: Actually report the size we're gonna allocate

Don't just pass on measure() calls, but actually behave in the way we
behave during size allocate.

This should improve cases where GtkScrolledWindow is used with GTK_POLICY_NEVER.
---
 gtk/gtkviewport.c | 100 +++++++++++++++++++++++-----------------------
 1 file changed, 50 insertions(+), 50 deletions(-)

diff --git a/gtk/gtkviewport.c b/gtk/gtkviewport.c
index 65561a7aaf..b301244946 100644
--- a/gtk/gtkviewport.c
+++ b/gtk/gtkviewport.c
@@ -143,17 +143,55 @@ gtk_viewport_buildable_init (GtkBuildableIface *iface)
   iface->add_child = gtk_viewport_buildable_add_child;
 }
 
+static void
+gtk_viewport_measure_child (GtkViewport *viewport,
+                            int          size[2])
+{
+  GtkOrientation orientation, opposite;
+  int min, nat;
+
+  if (viewport->child == NULL ||
+      !gtk_widget_is_visible (viewport->child))
+    {
+      size[0] = 0;
+      size[1] = 0;
+      return;
+    }
+
+  if (gtk_widget_get_request_mode (viewport->child) == GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT)
+    orientation = GTK_ORIENTATION_VERTICAL;
+  else
+    orientation = GTK_ORIENTATION_HORIZONTAL;
+  opposite = OPPOSITE_ORIENTATION (orientation);
+
+  gtk_widget_measure (viewport->child,
+                      orientation, -1,
+                      &min, &nat,
+                      NULL, NULL);
+  if (viewport->scroll_policy[orientation] == GTK_SCROLL_MINIMUM)
+    size[orientation] = min;
+  else
+    size[orientation] = nat;
+
+  gtk_widget_measure (viewport->child,
+                      opposite, size[orientation],
+                      &min, &nat,
+                      NULL, NULL);
+  if (viewport->scroll_policy[opposite] == GTK_SCROLL_MINIMUM)
+    size[opposite] = min;
+  else
+    size[opposite] = nat;
+}
+
 static void
 viewport_set_adjustment_values (GtkViewport    *viewport,
                                 GtkOrientation  orientation)
 {
   GtkAdjustment *adjustment;
-  GtkScrollablePolicy scroll_policy;
-  GtkScrollablePolicy other_scroll_policy;
-  GtkOrientation other_orientation;
   double upper, value;
-  int viewport_size, other_viewport_size;
+  int viewport_size;
   int view_width, view_height;
+  int child_size[2];
 
   view_width = gtk_widget_get_width (GTK_WIDGET (viewport));
   view_height = gtk_widget_get_height (GTK_WIDGET (viewport));
@@ -161,49 +199,17 @@ viewport_set_adjustment_values (GtkViewport    *viewport,
   if (orientation == GTK_ORIENTATION_HORIZONTAL)
     {
       adjustment = viewport->adjustment[GTK_ORIENTATION_HORIZONTAL];
-      other_orientation = GTK_ORIENTATION_VERTICAL;
       viewport_size = view_width;
-      other_viewport_size = view_height;
-      scroll_policy = viewport->scroll_policy[GTK_ORIENTATION_HORIZONTAL];
-      other_scroll_policy = viewport->scroll_policy[GTK_ORIENTATION_VERTICAL];
     }
   else /* VERTICAL */
     {
       adjustment = viewport->adjustment[GTK_ORIENTATION_VERTICAL];
-      other_orientation = GTK_ORIENTATION_HORIZONTAL;
       viewport_size = view_height;
-      other_viewport_size = view_width;
-      scroll_policy = viewport->scroll_policy[GTK_ORIENTATION_VERTICAL];
-      other_scroll_policy = viewport->scroll_policy[GTK_ORIENTATION_HORIZONTAL];
     }
 
+  gtk_viewport_measure_child (viewport, child_size);
 
-  if (viewport->child && gtk_widget_get_visible (viewport->child))
-    {
-      int min_size, nat_size;
-      int scroll_size;
-
-      if (other_scroll_policy == GTK_SCROLL_MINIMUM)
-        gtk_widget_measure (viewport->child, other_orientation, -1,
-                            &scroll_size, NULL, NULL, NULL);
-      else
-        gtk_widget_measure (viewport->child, other_orientation, -1,
-                            NULL, &scroll_size, NULL, NULL);
-
-      gtk_widget_measure (viewport->child, orientation,
-                          MAX (other_viewport_size, scroll_size),
-                          &min_size, &nat_size, NULL, NULL);
-
-      if (scroll_policy == GTK_SCROLL_MINIMUM)
-        upper = MAX (min_size, viewport_size);
-      else
-        upper = MAX (nat_size, viewport_size);
-
-    }
-  else
-    {
-      upper = viewport_size;
-    }
+  upper = MAX (viewport_size, child_size[orientation]);
 
   value = gtk_adjustment_get_value (adjustment);
 
@@ -236,13 +242,12 @@ gtk_viewport_measure (GtkWidget      *widget,
                       int            *natural_baseline)
 {
   GtkViewport *viewport = GTK_VIEWPORT (widget);
+  int child_size[2];
 
-  if (viewport->child)
-    gtk_widget_measure (viewport->child,
-                        orientation,
-                        for_size,
-                        minimum, natural,
-                        NULL, NULL);
+  gtk_viewport_measure_child (viewport, child_size);
+
+  *minimum = child_size[orientation];
+  *natural = child_size[orientation];
 }
 
 static void
@@ -267,12 +272,7 @@ gtk_viewport_compute_expand (GtkWidget *widget,
 static GtkSizeRequestMode
 gtk_viewport_get_request_mode (GtkWidget *widget)
 {
-  GtkViewport *viewport = GTK_VIEWPORT (widget);
-
-  if (viewport->child)
-    return gtk_widget_get_request_mode (viewport->child);
-  else
-    return GTK_SIZE_REQUEST_CONSTANT_SIZE;
+  return GTK_SIZE_REQUEST_CONSTANT_SIZE;
 }
 
 #define ADJUSTMENT_POINTER(orientation)            \