Add GtkMagnifier

This is a private widget that takes another widget on construction, and is able
to render parts of it, possibly at a different magnification level.

gtk/Makefile.am

@@ -490,6 +490,7 @@ gtk_private_h_sources =		\
 	gtkkeyhash.h		\
 	gtklabelprivate.h	\
 	gtklockbuttonprivate.h	\
+	gtkmagnifierprivate.h	\
 	gtkmenubuttonprivate.h	\
 	gtkmenuprivate.h	\
 	gtkmenuitemprivate.h	\
@@ -763,6 +764,7 @@ gtk_base_c_sources = 		\
 	gtkliststore.c		\
 	gtklockbutton.c		\
 	gtkmain.c		\
+	gtkmagnifier.c		\
 	gtkmarshalers.c		\
 	gtkmenu.c		\
 	gtkmenubar.c		\

gtk/gtkmagnifier.c

@@ -0,0 +1,269 @@
+/* GTK - The GIMP Toolkit
+ * Copyright © 2013 Carlos Garnacho <carlosg@gnome.org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+#include "gtk/gtk.h"
+#include "gtkmagnifierprivate.h"
+#include "gtkintl.h"
+
+enum {
+  PROP_INSPECTED = 1,
+  PROP_MAGNIFICATION
+};
+
+typedef struct _GtkMagnifierPrivate GtkMagnifierPrivate;
+
+struct _GtkMagnifierPrivate
+{
+  GtkWidget *inspected;
+  gdouble magnification;
+  gint x;
+  gint y;
+};
+
+G_DEFINE_TYPE_WITH_PRIVATE (GtkMagnifier, _gtk_magnifier,
+                            GTK_TYPE_WIDGET)
+
+static void
+_gtk_magnifier_set_property (GObject      *object,
+                             guint         param_id,
+                             const GValue *value,
+                             GParamSpec   *pspec)
+{
+  switch (param_id)
+    {
+    case PROP_INSPECTED:
+      _gtk_magnifier_set_inspected (GTK_MAGNIFIER (object),
+                                    g_value_get_object (value));
+      break;
+    case PROP_MAGNIFICATION:
+      _gtk_magnifier_set_magnification (GTK_MAGNIFIER (object),
+                                        g_value_get_double (value));
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, param_id, pspec);
+    }
+}
+
+static void
+_gtk_magnifier_get_property (GObject    *object,
+                             guint       param_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+  GtkMagnifier *magnifier;
+  GtkMagnifierPrivate *priv;
+
+  magnifier = GTK_MAGNIFIER (object);
+  priv = _gtk_magnifier_get_instance_private (magnifier);
+
+  switch (param_id)
+    {
+    case PROP_INSPECTED:
+      g_value_set_object (value, priv->inspected);
+      break;
+    case PROP_MAGNIFICATION:
+      g_value_set_double (value, priv->magnification);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, param_id, pspec);
+    }
+}
+
+static gboolean
+_gtk_magnifier_draw (GtkWidget *widget,
+                     cairo_t   *cr)
+{
+  GtkAllocation allocation, inspected_alloc;
+  GtkMagnifier *magnifier;
+  GtkMagnifierPrivate *priv;
+  gdouble x, y;
+
+  magnifier = GTK_MAGNIFIER (widget);
+  priv = _gtk_magnifier_get_instance_private (magnifier);
+
+  if (!gtk_widget_is_visible (priv->inspected))
+    return FALSE;
+
+  gtk_widget_get_allocation (widget, &allocation);
+  gtk_widget_get_allocation (priv->inspected, &inspected_alloc);
+  cairo_translate (cr, allocation.width / 2, allocation.height / 2);
+
+  x = CLAMP (priv->x, 0, inspected_alloc.width);
+  y = CLAMP (priv->y, 0, inspected_alloc.height);
+
+  cairo_save (cr);
+  cairo_scale (cr, priv->magnification, priv->magnification);
+  cairo_translate (cr, -x, -y);
+  gtk_widget_draw (priv->inspected, cr);
+  cairo_restore (cr);
+
+  return TRUE;
+}
+
+static void
+_gtk_magnifier_class_init (GtkMagnifierClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  object_class->set_property = _gtk_magnifier_set_property;
+  object_class->get_property = _gtk_magnifier_get_property;
+
+  widget_class->draw = _gtk_magnifier_draw;
+
+  g_object_class_install_property (object_class,
+                                   PROP_INSPECTED,
+                                   g_param_spec_object (P_("inspected"),
+                                                        P_("Inspected"),
+                                                        P_("Inspected widget"),
+                                                        GTK_TYPE_WIDGET,
+                                                        G_PARAM_READWRITE));
+  g_object_class_install_property (object_class,
+                                   PROP_MAGNIFICATION,
+                                   g_param_spec_double (P_("magnification"),
+                                                        P_("magnification"),
+                                                        P_("magnification"),
+                                                        1, G_MAXDOUBLE, 1,
+                                                        G_PARAM_READWRITE));
+}
+
+static void
+_gtk_magnifier_init (GtkMagnifier *magnifier)
+{
+  GtkWidget *widget = GTK_WIDGET (magnifier);
+  GtkMagnifierPrivate *priv;
+
+  priv = _gtk_magnifier_get_instance_private (magnifier);
+
+  gtk_widget_set_events (widget,
+                         gtk_widget_get_events (widget) |
+                         GDK_EXPOSURE_MASK);
+
+  gtk_widget_set_has_window (widget, FALSE);
+  priv->magnification = 1;
+}
+
+GtkWidget *
+_gtk_magnifier_new (GtkWidget *inspected)
+{
+  g_return_val_if_fail (GTK_IS_WIDGET (inspected), NULL);
+
+  return g_object_new (GTK_TYPE_MAGNIFIER,
+                       "inspected", inspected,
+                       NULL);
+}
+
+GtkWidget *
+_gtk_magnifier_get_inspected (GtkMagnifier *magnifier)
+{
+  GtkMagnifierPrivate *priv;
+
+  g_return_val_if_fail (GTK_IS_MAGNIFIER (magnifier), NULL);
+
+  priv = _gtk_magnifier_get_instance_private (magnifier);
+
+  return priv->inspected;
+}
+
+void
+_gtk_magnifier_set_inspected (GtkMagnifier *magnifier,
+                              GtkWidget    *inspected)
+{
+  GtkMagnifierPrivate *priv;
+
+  g_return_val_if_fail (GTK_IS_MAGNIFIER (magnifier), NULL);
+
+  priv = _gtk_magnifier_get_instance_private (magnifier);
+
+  if (priv->inspected == inspected)
+    return;
+
+  priv->inspected = inspected;
+  g_object_notify (G_OBJECT (magnifier), "inspected");
+}
+
+void
+_gtk_magnifier_set_coords (GtkMagnifier *magnifier,
+                           gdouble       x,
+                           gdouble       y)
+{
+  GtkMagnifierPrivate *priv;
+
+  g_return_if_fail (GTK_IS_MAGNIFIER (magnifier));
+
+  priv = _gtk_magnifier_get_instance_private (magnifier);
+
+  if (priv->x == x && priv->y == y)
+    return;
+
+  priv->x = x;
+  priv->y = y;
+
+  if (gtk_widget_is_visible (GTK_WIDGET (magnifier)))
+    gtk_widget_queue_draw (GTK_WIDGET (magnifier));
+}
+
+void
+_gtk_magnifier_get_coords (GtkMagnifier *magnifier,
+                           gdouble      *x,
+                           gdouble      *y)
+{
+  GtkMagnifierPrivate *priv;
+
+  g_return_if_fail (GTK_IS_MAGNIFIER (magnifier));
+
+  priv = _gtk_magnifier_get_instance_private (magnifier);
+
+  if (x)
+    *x = priv->x;
+
+  if (y)
+    *y = priv->y;
+}
+
+void
+_gtk_magnifier_set_magnification (GtkMagnifier *magnifier,
+                                  gdouble       magnification)
+{
+  GtkMagnifierPrivate *priv;
+
+  g_return_if_fail (GTK_IS_MAGNIFIER (magnifier));
+
+  priv = _gtk_magnifier_get_instance_private (magnifier);
+
+  if (priv->magnification == magnification)
+    return;
+
+  priv->magnification = magnification;
+  g_object_notify (G_OBJECT (magnifier), "magnification");
+
+  if (gtk_widget_is_visible (GTK_WIDGET (magnifier)))
+    gtk_widget_queue_draw (GTK_WIDGET (magnifier));
+}
+
+gdouble
+_gtk_magnifier_get_magnification (GtkMagnifier *magnifier)
+{
+  GtkMagnifierPrivate *priv;
+
+  g_return_val_if_fail (GTK_IS_MAGNIFIER (magnifier), 1);
+
+  priv = _gtk_magnifier_get_instance_private (magnifier);
+
+  return priv->magnification;
+}

gtk/gtkmagnifierprivate.h

@@ -0,0 +1,64 @@
+/* GTK - The GIMP Toolkit
+ * Copyright © 2013 Carlos Garnacho <carlosg@gnome.org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GTK_MAGNIFIER_H__
+#define __GTK_MAGNIFIER_H__
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_MAGNIFIER           (_gtk_magnifier_get_type ())
+#define GTK_MAGNIFIER(o)             (G_TYPE_CHECK_INSTANCE_CAST ((o), GTK_TYPE_MAGNIFIER, GtkMagnifier))
+#define GTK_MAGNIFIER_CLASS(c)       (G_TYPE_CHECK_CLASS_CAST ((c), GTK_TYPE_MAGNIFIER, GtkMagnifierClass))
+#define GTK_IS_MAGNIFIER(o)          (G_TYPE_CHECK_INSTANCE_TYPE ((o), GTK_TYPE_MAGNIFIER))
+#define GTK_IS_MAGNIFIER_CLASS(o)    (G_TYPE_CHECK_CLASS_TYPE ((o), GTK_TYPE_MAGNIFIER))
+#define GTK_MAGNIFIER_GET_CLASS(o)   (G_TYPE_INSTANCE_GET_CLASS ((o), GTK_TYPE_MAGNIFIER, GtkMagnifierClass))
+
+typedef struct _GtkMagnifier GtkMagnifier;
+typedef struct _GtkMagnifierClass GtkMagnifierClass;
+
+struct _GtkMagnifier
+{
+  GtkWidget parent_instance;
+};
+
+struct _GtkMagnifierClass
+{
+  GtkWidgetClass parent_class;
+};
+
+GType       _gtk_magnifier_get_type          (void) G_GNUC_CONST;
+
+GtkWidget * _gtk_magnifier_new               (GtkWidget       *inspected);
+
+GtkWidget * _gtk_magnifier_get_inspected     (GtkMagnifier *magnifier);
+void        _gtk_magnifier_set_inspected     (GtkMagnifier *magnifier,
+                                              GtkWidget    *inspected);
+
+void        _gtk_magnifier_set_coords        (GtkMagnifier *magnifier,
+                                              gdouble       x,
+                                              gdouble       y);
+void        _gtk_magnifier_get_coords        (GtkMagnifier *magnifier,
+                                              gdouble      *x,
+                                              gdouble      *y);
+
+void        _gtk_magnifier_set_magnification (GtkMagnifier *magnifier,
+                                              gdouble       magnification);
+gdouble     _gtk_magnifier_get_magnification (GtkMagnifier *magnifier);
+
+G_END_DECLS
+
+#endif /* __GTK_MAGNIFIER_H__ */