[gtk/wip/layout-manager] wip: Add GtkBoxLayout

[Emmanuele Bassi <ebassi src gnome org>]

commit 8996cb133a12ba556efa68b45ac2468ad29a0a55
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Wed Dec 19 17:32:24 2018 +0000

    wip: Add GtkBoxLayout
    
    The same layout policy of GtkBox, without all the GtkContainer calories.

 gtk/gtkboxlayout.c | 291 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 gtk/gtkboxlayout.h |  27 +++++
 2 files changed, 318 insertions(+)
---
diff --git a/gtk/gtkboxlayout.c b/gtk/gtkboxlayout.c
new file mode 100644
index 0000000000..f5973d4812
--- /dev/null
+++ b/gtk/gtkboxlayout.c
@@ -0,0 +1,291 @@
+#include "config.h"
+
+#include "gtkboxlayout.h"
+
+#include "gtkorientable.h"
+#include "gtksizerequest.h"
+#include "gtkprivate.h"
+
+/**
+ * SECTION:gtkboxlayout
+ * @Title: GtkBoxLayout
+ * @Short_description: Layout manager for placing all children in a single row or column
+ *
+ * ...
+ */
+
+struct _GtkBoxLayout
+{
+  GtkLayoutManager parent_instance;
+
+  gboolean homogeneous;
+  guint spacing;
+  GtkOrientation orientation;
+};
+
+G_DEFINE_TYPE_WITH_CODE (GtkBoxLayout, gtk_box_layout, GTK_TYPE_LAYOUT_MANAGER,
+                         G_IMPLEMENT_INTERFACE (GTK_TYPE_ORIENTABLE, NULL))
+
+enum {
+  PROP_HOMOGENEOUS = 1,
+  PROP_SPACING,
+
+  PROP_ORIENTATION,
+  N_PROPS = PROP_ORIENTATION
+};
+
+static GParamSpec *box_layout_props[N_PROPS];
+
+static void
+gtk_box_layout_set_property (GObject      *gobject,
+                             guint         prop_id,
+                             const GValue *value,
+                             GParamSpec   *pspec)
+{
+  GtkBoxLayout *box_layout = GTK_BOX_LAYOUT (gobject);
+
+  switch (prop_id)
+    {
+    case PROP_HOMOGENEOUS:
+      gtk_box_layout_set_homogeneous (box_layout, g_value_get_boolean (value));
+      break;
+
+    case PROP_SPACING:
+      gtk_box_layout_set_spacing (box_layout, g_value_get_int (value));
+      break;
+
+    case PROP_ORIENTATION:
+      gtk_orientable_set_orientation (GTK_ORIENTABLE (box_layout),
+                                      g_value_get_enum (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROP_ID (gobject, prop_id, pspec);
+    }
+}
+
+static void
+gtk_box_layout_get_property (GObject    *gobject,
+                             guint       prop_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+  GtkBoxLayout *box_layout = GTK_BOX_LAYOUT (gobject);
+
+  switch (prop_id)
+    {
+    case PROP_HOMOGENEOUS:
+      g_value_set_boolean (value, box_layout->homogeneous);
+      break;
+
+    case PROP_SPACING:
+      g_value_set_int (value, box_layout->spacing);
+      break;
+
+    case PROP_ORIENTATION:
+      g_value_set_enum (value, box_layout->orientation);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROP_ID (gobject, prop_id, pspec);
+    }
+}
+
+static GtkSizeRequestMode
+gtk_box_layout_get_request_mode (GtkLayoutManager *layout_manager,
+                                 GtkWidget        *widget)
+{
+  GtkBoxLayout *box_layout = GTK_BOX_LAYOUT (layout_manager);
+
+  return box_layout->orientation == GTK_ORIENTATION_HORIZONTAL
+    ? GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT
+    : GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH;
+}
+
+static void
+gtk_box_layout_compute_size (GtkBoxLayout *box_layout,
+                             GtkWidget    *widget,
+                             int           for_size,
+                             int          *minimum,
+                             int          *natural)
+{
+  GtkWidget *child;
+  int n_visible_children = 0;
+  int required_min = 0, required_nat = 0;
+  int largest_min = 0, largest_nat = 0;
+
+  for (child = gtk_widget_get_first_child (widget);
+       child != NULL;
+       child = gtk_widget_get_next_sibling (child))
+    {
+      int child_min = 0;
+      int child_nat = 0;
+
+      if (!_gtk_widget_get_visible (child))
+        continue;
+
+      gtk_widget_measure (child, box_layout->orientation,
+                          for_size,
+                          &child_min, &child_nat,
+                          NULL, NULL);
+
+      largest_min = MAX (largest_min, child_min);
+      largest_nat = MAX (largest_nat, child_nat);
+
+      required_min += child_min;
+      required_nat += child_nat;
+
+      n_visible_children += 1;
+    }
+
+  if (n_visible_children > 0)
+    {
+      if (box_layout->homogeneous)
+        {
+          required_min = largest_min * n_visible_children;
+          required_nat = largest_nat * n_visible_children;
+        }
+
+      required_min += (n_visible_children - 1) * spacing;
+      required_nat += (n_visible_children - 1) * spacing;
+    }
+
+  *minimum = required_min;
+  *natural = required_nat;
+}
+
+static void
+gtk_box_layout_compute_opposite_size (GtkBoxLayout *box_layout,
+                                      GtkWidget    *widget,
+                                      int           for_size,
+                                      int          *minimum,
+                                      int          *natural,
+                                      int          *min_baseline,
+                                      int          *nat_baseline)
+{
+}
+
+static void
+gtk_box_layout_measure (GtkLayoutManager *layout_manager,
+                        GtkWidget        *widget,
+                        GtkOrientation    orientation,
+                        int               for_size,
+                        int              *minimum,
+                        int              *natural,
+                        int              *min_baseline,
+                        int              *nat_baseline)
+{
+  GtkBoxLayout *box_layout = GTK_BOX_LAYOUT (layout_manager);
+
+  if (box_layout->orientation != orientation)
+    {
+      gtk_box_layout_compute_opposite_size (box_layout, widget, for_size,
+                                            minimum, natural,
+                                            min_baseline, nat_baseline);
+    }
+  else
+    {
+      gtk_box_layout_compute_size (box_layout, widget, for_size,
+                                   minimum, natural);
+    }
+}
+
+static void
+gtk_box_layout_allocate (GtkLayoutManager *layout_manager,
+                         GtkWidget        *widget,
+                         int               width,
+                         int               height,
+                         int               baseline)
+{
+}
+
+static void
+gtk_box_layout_class_init (GtkBoxLayoutClass *klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+  GtkLayoutManagerClass *layout_manager_class = GTK_LAYOUT_MANAGER (klass);
+
+  gobject_class->set_property = gtk_box_layout_set_property;
+  gobject_class->get_property = gtk_box_layout_get_property;
+
+  layout_manager_class->get_request_mode = gtk_box_layout_get_request_mode;
+  layout_manager_class->measure = gtk_box_layout_measure;
+  layout_manager_class->allocate = gtk_box_layout_allocate;
+
+  box_layout_props[PROP_HOMOGENEOUS] =
+    g_param_spec_boolean ("homogeneous", "Homogeneous", "Distribute space homogeneously",
+                          FALSE,
+                          GTK_PARAM_READWRITE |
+                          G_PARAM_EXPLICIT_NOTIFY);
+
+  box_layout_props[PROP_SPACING] =
+    g_param_spec_int ("spacing", "Spacing", "Spacing between widgets",
+                      0, G_MAXINT, 0,
+                      GTK_PARAM_READWRITE |
+                      G_PARAM_EXPLICIT_NOTIFY);
+
+  g_object_class_install_properties (gobject_class, N_PROPS, box_layout_props);
+  g_object_class_override_property (gobject_class, PROP_ORIENTATION, "orientation");
+}
+
+static void
+gtk_box_layout_init (GtkBoxLayout *self)
+{
+  self->homogeneous = FALSE;
+  self->spacing = 0;
+  self->orientation = GTK_ORIENTATION_HORIZONTAL;
+}
+
+GtkLayoutManager *
+gtk_box_layout_new (GtkOrientation orientation)
+{
+  return g_object_new (GTK_TYPE_BOX_LAYOUT,
+                       "orientation", orientation,
+                       NULL);
+}
+
+void
+gtk_box_layout_set_homogeneous (GtkBoxLayout *box_layout,
+                                gboolean      homogeneous)
+{
+  g_return_if_fail (GTK_IS_BOX_LAYOUT (box_layout));
+
+  if (box_layout->homogeneous == (!!homogeneous))
+    return;
+
+  box_layout->homogeneous = !!homogeneous;
+
+  gtk_layout_manager_layout_changed (GTK_LAYOUT_MANAGER (box_layout));
+  g_object_notify_by_pspec (G_OBJECT (box_layout), box_layout_props[PROP_HOMOGENEOUS]);
+}
+
+gboolean
+gtk_box_layout_get_homogeneous (GtkBoxLayout *box_layout)
+{
+  g_return_val_if_fail (GTK_IS_BOX_LAYOUT (box_layout), FALSE);
+
+  return box_layout->homogeneous;
+}
+
+void
+gtk_box_layout_set_spacing (GtkBoxLayout *box_layout,
+                            guint         spacing)
+{
+  g_return_if_fail (GTK_IS_BOX_LAYOUT (box_layout));
+
+  if (box_layout->spacing == spacing)
+    return;
+
+  box_layout->spacing = spacing;
+
+  gtk_layout_manager_layout_changed (GTK_LAYOUT_MANAGER (box_layout));
+  g_object_notify_by_pspec (G_OBJECT (box_layout), box_layout_props[PROP_SPACING]);
+}
+
+guint
+gtk_box_layout_get_spacing (GtkBoxLayout *box_layout)
+{
+  g_return_val_if_fail (GTK_IS_BOX_LAYOUT (box_layout), 0);
+
+  return box_layout->spacing;
+}
diff --git a/gtk/gtkboxlayout.h b/gtk/gtkboxlayout.h
new file mode 100644
index 0000000000..08d87efeca
--- /dev/null
+++ b/gtk/gtkboxlayout.h
@@ -0,0 +1,27 @@
+#pragma once
+
+#include <gtk/gtkenums.h>
+#include <gtk/gtklayoutmanager.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_BOX_LAYOUT (gtk_box_layout_get_type())
+
+GDK_AVAILABLE_IN_ALL
+G_DECLARE_FINAL_TYPE (GtkBoxLayout, gtk_box_layout, GTK, BOX_LAYOUT, GtkLayoutManager)
+
+GDK_AVAILABLE_IN_ALL
+GtkLayoutManager *      gtk_box_layout_new              (GtkOrientation  orientation);
+
+GDK_AVAILABLE_IN_ALL
+void                    gtk_box_layout_set_homogeneous  (GtkBoxLayout   *box_layout,
+                                                         gboolean        homogeneous);
+GDK_AVAILABLE_IN_ALL
+gboolean                gtk_box_layout_get_homogeneous  (GtkBoxLayout   *box_layout);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_box_layout_set_spacing      (GtkBoxLayout   *box_layout,
+                                                         guint           spacing);
+GDK_AVAILABLE_IN_ALL
+guint                   gtk_box_layout_get_spacing      (GtkBoxLayout   *box_layout);
+
+G_END_DECLS