[libhandy] squeezer: Add the xalign and yalign properties

[Alexander Mikhaylenko <alexm src gnome org>]

commit fcd55f1b17729d201a97414a9e32e0c0bd6cb1c9
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Tue Jul 21 09:37:37 2020 +0200

    squeezer: Add the xalign and yalign properties
    
    This also centers the children by default instead of aligning them to
    the start and the top when they are larger than the squeezer, as the
    default xalign and yalign values are 0.5.
    
    Fixes https://gitlab.gnome.org/GNOME/libhandy/-/issues/226

 debian/libhandy-1-0.symbols |   4 ++
 src/hdy-squeezer.c          | 158 +++++++++++++++++++++++++++++++++++++++++++-
 src/hdy-squeezer.h          |  12 ++++
 3 files changed, 171 insertions(+), 3 deletions(-)
---
diff --git a/debian/libhandy-1-0.symbols b/debian/libhandy-1-0.symbols
index ef38e67e..0c3fc88b 100644
--- a/debian/libhandy-1-0.symbols
+++ b/debian/libhandy-1-0.symbols
@@ -247,12 +247,16 @@ libhandy-1.so.0 libhandy-1-0 #MINVER#
  hdy_squeezer_get_transition_type@LIBHANDY_1_0 0.0.10
  hdy_squeezer_get_type@LIBHANDY_1_0 0.0.10
  hdy_squeezer_get_visible_child@LIBHANDY_1_0 0.0.10
+ hdy_squeezer_get_xalign@LIBHANDY_1_0 0.85.0
+ hdy_squeezer_get_yalign@LIBHANDY_1_0 0.85.0
  hdy_squeezer_new@LIBHANDY_1_0 0.0.10
  hdy_squeezer_set_child_enabled@LIBHANDY_1_0 0.0.10
  hdy_squeezer_set_homogeneous@LIBHANDY_1_0 0.0.10
  hdy_squeezer_set_interpolate_size@LIBHANDY_1_0 0.0.10
  hdy_squeezer_set_transition_duration@LIBHANDY_1_0 0.0.10
  hdy_squeezer_set_transition_type@LIBHANDY_1_0 0.0.10
+ hdy_squeezer_set_xalign@LIBHANDY_1_0 0.85.0
+ hdy_squeezer_set_yalign@LIBHANDY_1_0 0.85.0
  hdy_squeezer_transition_type_get_type@LIBHANDY_1_0 0.0.10
  hdy_swipe_group_add_swipeable@LIBHANDY_1_0 0.0.12
  hdy_swipe_group_get_swipeables@LIBHANDY_1_0 0.0.12
diff --git a/src/hdy-squeezer.c b/src/hdy-squeezer.c
index 714c3e64..7cf694bc 100644
--- a/src/hdy-squeezer.c
+++ b/src/hdy-squeezer.c
@@ -58,11 +58,13 @@ enum  {
   PROP_TRANSITION_TYPE,
   PROP_TRANSITION_RUNNING,
   PROP_INTERPOLATE_SIZE,
+  PROP_XALIGN,
+  PROP_YALIGN,
 
   /* Overridden properties */
   PROP_ORIENTATION,
 
-  LAST_PROP = PROP_INTERPOLATE_SIZE + 1,
+  LAST_PROP = PROP_YALIGN + 1,
 };
 
 enum {
@@ -108,6 +110,9 @@ struct _HdySqueezer
 
   gboolean interpolate_size;
 
+  gfloat xalign;
+  gfloat yalign;
+
   GtkOrientation orientation;
 };
 
@@ -473,6 +478,12 @@ hdy_squeezer_get_property (GObject    *object,
   case PROP_INTERPOLATE_SIZE:
     g_value_set_boolean (value, hdy_squeezer_get_interpolate_size (self));
     break;
+  case PROP_XALIGN:
+    g_value_set_float (value, hdy_squeezer_get_xalign (self));
+    break;
+  case PROP_YALIGN:
+    g_value_set_float (value, hdy_squeezer_get_yalign (self));
+    break;
   case PROP_ORIENTATION:
     g_value_set_enum (value, get_orientation (self));
     break;
@@ -503,6 +514,12 @@ hdy_squeezer_set_property (GObject      *object,
   case PROP_INTERPOLATE_SIZE:
     hdy_squeezer_set_interpolate_size (self, g_value_get_boolean (value));
     break;
+  case PROP_XALIGN:
+    hdy_squeezer_set_xalign (self, g_value_get_float (value));
+    break;
+  case PROP_YALIGN:
+    hdy_squeezer_set_yalign (self, g_value_get_float (value));
+    break;
   case PROP_ORIENTATION:
     set_orientation (self, g_value_get_enum (value));
     break;
@@ -672,9 +689,12 @@ hdy_squeezer_draw_crossfade (GtkWidget *widget,
   cairo_paint (cr);
 
   if (self->last_visible_surface != NULL) {
+    gint width_diff = gtk_widget_get_allocated_width (widget) - self->last_visible_surface_allocation.width;
+    gint height_diff = gtk_widget_get_allocated_height (widget) - 
self->last_visible_surface_allocation.height;
+
     cairo_set_source_surface (cr, self->last_visible_surface,
-                              self->last_visible_surface_allocation.x,
-                              self->last_visible_surface_allocation.y);
+                              width_diff * self->xalign,
+                              height_diff * self->yalign);
     cairo_set_operator (cr, CAIRO_OPERATOR_ADD);
     cairo_paint_with_alpha (cr, MAX (1.0 - progress, 0));
   }
@@ -1104,6 +1124,50 @@ hdy_squeezer_class_init (HdySqueezerClass *klass)
                             FALSE,
                             G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
 
+  /**
+   * HdySqueezer:xalign:
+   *
+   * The xalign property determines the horizontal aligment of the children
+   * inside the squeezer's size allocation.
+   * Compare this to #GtkWidget:halign, which determines how the squeezer's size
+   * allocation is positioned in the space available for the squeezer.
+   * The range goes from 0 (start) to 1 (end).
+   *
+   * This will affect the position of children too wide to fit in the squeezer
+   * as they are fading out.
+   *
+   * Since: 1.0
+   */
+  props[PROP_XALIGN] =
+    g_param_spec_float ("xalign",
+                        _("X align"),
+                        _("The horizontal alignment, from 0 (start) to 1 (end)"),
+                        0.0, 1.0,
+                        0.5,
+                        G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
+
+  /**
+   * HdySqueezer:yalign:
+   *
+   * The yalign property determines the vertical aligment of the children inside
+   * the squeezer's size allocation.
+   * Compare this to #GtkWidget:valign, which determines how the squeezer's size
+   * allocation is positioned in the space available for the squeezer.
+   * The range goes from 0 (top) to 1 (bottom).
+   *
+   * This will affect the position of children too tall to fit in the squeezer
+   * as they are fading out.
+   *
+   * Since: 1.0
+   */
+  props[PROP_YALIGN] =
+    g_param_spec_float ("yalign",
+                        _("Y align"),
+                        _("The vertical alignment, from 0 (top) to 1 (bottom)"),
+                        0.0, 1.0,
+                        0.5,
+                        G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
+
   g_object_class_install_properties (object_class, LAST_PROP, props);
 
   child_props[CHILD_PROP_ENABLED] =
@@ -1127,6 +1191,8 @@ hdy_squeezer_init (HdySqueezer *self)
   self->homogeneous = TRUE;
   self->transition_duration = 200;
   self->transition_type = HDY_SQUEEZER_TRANSITION_TYPE_NONE;
+  self->xalign = 0.5;
+  self->yalign = 0.5;
 }
 
 /**
@@ -1417,3 +1483,89 @@ hdy_squeezer_set_child_enabled (HdySqueezer *self,
   child_info->enabled = enabled;
   gtk_widget_queue_resize (GTK_WIDGET (self));
 }
+
+/**
+ * hdy_squeezer_get_xalign:
+ * @self: a #HdySqueezer
+ *
+ * Gets the #HdySqueezer:xalign property for @self.
+ *
+ * Returns: the xalign property
+ *
+ * Since: 1.0
+ */
+gfloat
+hdy_squeezer_get_xalign (HdySqueezer *self)
+{
+  g_return_val_if_fail (HDY_IS_SQUEEZER (self), 0.5);
+
+  return self->xalign;
+}
+
+/**
+ * hdy_squeezer_set_xalign:
+ * @self: a #HdySqueezer
+ * @xalign: the new xalign value, between 0 and 1
+ *
+ * Sets the #HdySqueezer:xalign property for @self.
+ *
+ * Since: 1.0
+ */
+void
+hdy_squeezer_set_xalign (HdySqueezer *self,
+                         gfloat       xalign)
+{
+  g_return_if_fail (HDY_IS_SQUEEZER (self));
+
+  xalign = CLAMP (xalign, 0.0, 1.0);
+
+  if (self->xalign == xalign)
+    return;
+
+  self->xalign = xalign;
+  gtk_widget_queue_draw (GTK_WIDGET (self));
+  g_object_notify_by_pspec (G_OBJECT (self), props[PROP_XALIGN]);
+}
+
+/**
+ * hdy_squeezer_get_yalign:
+ * @self: a #HdySqueezer
+ *
+ * Gets the #HdySqueezer:yalign property for @self.
+ *
+ * Returns: the yalign property
+ *
+ * Since: 1.0
+ */
+gfloat
+hdy_squeezer_get_yalign (HdySqueezer *self)
+{
+  g_return_val_if_fail (HDY_IS_SQUEEZER (self), 0.5);
+
+  return self->yalign;
+}
+
+/**
+ * hdy_squeezer_set_yalign:
+ * @self: a #HdySqueezer
+ * @yalign: the new yalign value, between 0 and 1
+ *
+ * Sets the #HdySqueezer:yalign property for @self.
+ *
+ * Since: 1.0
+ */
+void
+hdy_squeezer_set_yalign (HdySqueezer *self,
+                         gfloat       yalign)
+{
+  g_return_if_fail (HDY_IS_SQUEEZER (self));
+
+  yalign = CLAMP (yalign, 0.0, 1.0);
+
+  if (self->yalign == yalign)
+    return;
+
+  self->yalign = yalign;
+  gtk_widget_queue_draw (GTK_WIDGET (self));
+  g_object_notify_by_pspec (G_OBJECT (self), props[PROP_YALIGN]);
+}
diff --git a/src/hdy-squeezer.h b/src/hdy-squeezer.h
index 251b7910..9b981163 100644
--- a/src/hdy-squeezer.h
+++ b/src/hdy-squeezer.h
@@ -68,4 +68,16 @@ void     hdy_squeezer_set_child_enabled (HdySqueezer *self,
                                          GtkWidget   *child,
                                          gboolean     enabled);
 
+HDY_AVAILABLE_IN_ALL
+gfloat hdy_squeezer_get_xalign (HdySqueezer *self);
+HDY_AVAILABLE_IN_ALL
+void   hdy_squeezer_set_xalign (HdySqueezer *self,
+                                gfloat       xalign);
+
+HDY_AVAILABLE_IN_ALL
+gfloat hdy_squeezer_get_yalign (HdySqueezer *self);
+HDY_AVAILABLE_IN_ALL
+void   hdy_squeezer_set_yalign (HdySqueezer *self,
+                                gfloat       yalign);
+
 G_END_DECLS