[dia] [gradient] introduce DiaPattern object

[Hans Breuer <hans src gnome org>]

commit b053d7a17506f5a88e94ec6b5c8cce2265e4e69c
Author: Hans Breuer <hans breuer org>
Date:   Tue Dec 24 15:11:21 2013 +0100

    [gradient] introduce DiaPattern object
    
    Step 1 of 7 for gradient support in Dia: the basic object currently can
    hold radial and linear gradient information.

 lib/diatypes.h |    3 +
 lib/libdia.def |   15 +++
 lib/pattern.c  |  260 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/pattern.h  |   63 ++++++++++++++
 4 files changed, 341 insertions(+), 0 deletions(-)
---
diff --git a/lib/diatypes.h b/lib/diatypes.h
index af000af..35b38fc 100644
--- a/lib/diatypes.h
+++ b/lib/diatypes.h
@@ -136,6 +136,9 @@ typedef struct _OrthConn OrthConn;
 /* In paper.h: */
 typedef struct _PaperInfo PaperInfo;
 
+/* In pattern.h: */
+typedef struct _DiaPattern DiaPattern;
+
 /* In plug-ins.h: */
 typedef struct _PluginInfo PluginInfo;
 
diff --git a/lib/libdia.def b/lib/libdia.def
index b50df4e..1578535 100644
--- a/lib/libdia.def
+++ b/lib/libdia.def
@@ -295,6 +295,21 @@ EXPORTS
 
  dia_path_renderer_get_type
 
+ dia_pattern_new
+ dia_pattern_add_color
+ dia_pattern_foreach
+ dia_pattern_get_fallback_color
+ dia_pattern_get_points
+ dia_pattern_get_radius
+ dia_pattern_get_settings
+ dia_pattern_set_pattern
+ dia_pattern_set_point
+ dia_pattern_set_radius
+ dia_pattern_release
+ data_add_pattern
+ data_pattern
+ dia_object_set_pattern
+
  dia_interactive_renderer_interface_get_type
  
  dialog_make
diff --git a/lib/pattern.c b/lib/pattern.c
new file mode 100644
index 0000000..a7f93e5
--- /dev/null
+++ b/lib/pattern.c
@@ -0,0 +1,260 @@
+/* Dia -- an diagram creation/manipulation program
+ * Copyright (C) 1998 Alexander Larsson
+ *
+ * pattern.h - implementation of DiaPattern object
+ * Copyright (C) 2013 Hans Breuer
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+#include <config.h> 
+#include "diatypes.h"
+#include "pattern.h"
+#include "color.h"
+#include <glib-object.h>
+
+typedef struct _DiaPatternClass DiaPatternClass;
+#define DIA_TYPE_PATTERN (_dia_pattern_get_type ())
+static GType _dia_pattern_get_type (void) G_GNUC_CONST;
+
+typedef struct _ColorStop
+{
+  Color color;
+  real  offset;
+} ColorStop;
+
+struct _DiaPattern
+{
+  GObject parent_instance;
+  /*< private >*/
+  DiaPatternType type;
+  Point          start;
+  real           radius;
+  Point          other;
+  GArray        *stops;
+
+  guint          flags;
+};
+
+struct _DiaPatternClass
+{
+  GObjectClass parent_class;
+};
+
+G_DEFINE_TYPE (DiaPattern, _dia_pattern, G_TYPE_OBJECT);
+static gpointer parent_class = NULL;
+
+static void
+_dia_pattern_finalize(GObject *object)
+{
+  DiaPattern *pattern = (DiaPattern *)object;
+
+  g_array_free (pattern->stops, TRUE);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+};
+
+static void
+_dia_pattern_class_init(DiaPatternClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  parent_class = g_type_class_peek_parent (klass);
+  object_class->finalize = _dia_pattern_finalize;
+}
+static void
+_dia_pattern_init(DiaPattern *self)
+{
+  self->other.x = 1.0;
+  self->other.y = 0.0;
+  self->radius  = 0.5;
+  self->stops = g_array_new (FALSE, FALSE, sizeof(ColorStop));
+}
+
+/*!
+ * \brief Create a new gradient object
+ *
+ * Create a default initialized pattern object. For gradients at least
+ * dia_pattern_add_color() should be called on it.
+ *
+ * \ingroup DiaPattern
+ */
+DiaPattern *
+dia_pattern_new (DiaPatternType pt, guint flags, real x, real y)
+{
+  DiaPattern *pat = g_object_new (DIA_TYPE_PATTERN, NULL);
+  pat->type = pt;
+  pat->start.x = x;
+  pat->start.y = y;
+  pat->flags = flags;
+
+  return pat;
+}
+
+/*!
+ * \brief Set the other point of the pattern
+ *
+ * The meaning of the point depends on the type of the pattern.
+ * For line gradient it is the second point giving the direction.
+ * With a radial gradient it is the focal point.
+ *
+ * \ingroup DiaPattern
+ */
+void
+dia_pattern_set_point (DiaPattern *self, real x, real y)
+{
+  self->other.x = x;
+  self->other.y = y;
+  /* with radial we have to ensure the point is in circle */
+  if (self->type == DIA_RADIAL_GRADIENT) {
+    real dist = distance_ellipse_point (&self->start, self->radius*2, self->radius*2, 0.0, &self->other);
+    if (dist > 0) {
+      /* If the point defined by �fx� and �fy� lies outside the circle defined
+       * by �cx�, �cy� and �r�, then the user agent shall set the focal point to
+       * the intersection of the line from (�cx�, �cy�) to (�fx�, �fy�) with the
+       * circle defined by �cx�, �cy� and �r�
+       */
+      Point p1 = self->start;
+      Point p2 = self->other;
+      point_sub (&p2, &p1);
+      point_normalize (&p2);
+      point_add_scaled (&p1, &p2, self->radius);
+      self->other = p1;
+    }
+  }
+}
+/*!
+ * \brief Set the radius of a radial gradient
+ * \ingroup DiaPattern
+ */
+void
+dia_pattern_set_radius (DiaPattern *self, real r)
+{
+  g_return_if_fail (self != NULL);
+  self->radius = r;
+}
+/*!
+ * \brief Get construction parameters of the pattern
+ * \ingroup DiaPattern
+ */
+void
+dia_pattern_get_settings (DiaPattern *self, DiaPatternType *type, guint *flags)
+{
+  g_return_if_fail (self != NULL);
+
+  if (type)
+    *type = self->type;
+  if (flags)
+    *flags = self->flags;
+}
+/*!
+ * \brief Get both points of the pattern definition
+ * The meaning of p2 is gradient type specific. 
+ * \ingroup DiaPattern
+ */
+void
+dia_pattern_get_points (DiaPattern *self, Point *p1, Point *p2)
+{
+  g_return_if_fail (self != NULL);
+
+  if (p1)
+    *p1 = self->start;
+  if (p2)
+    *p2 = self->other;
+}
+/*!
+ * \brief Get the radius of a radial gradient
+ * \ingroup DiaPattern
+ */
+void
+dia_pattern_get_radius (DiaPattern *self, real *r)
+{
+  g_return_if_fail (self != NULL);
+
+  if (r)
+    *r = self->radius;
+}
+
+/*!
+ * \brief Add a color stop to the gradient
+ * \ingroup DiaPattern
+ */
+void
+dia_pattern_add_color (DiaPattern *self, real pos, const Color *color)
+{
+  ColorStop stop;
+
+  g_return_if_fail (self != NULL && color != NULL);
+  stop.color  = *color;
+  stop.offset = pos;
+  g_array_append_val (self->stops, stop);
+}
+
+/*!
+ * \brief Inherit color stops from one gradient to the other
+ * \ingroup DiaPattern
+ */
+void
+dia_pattern_set_pattern (DiaPattern *self, DiaPattern *pat)
+{
+  gsize i;
+ 
+  g_return_if_fail (self != NULL && pat != NULL);
+
+  for (i = 0; i < pat->stops->len; ++i) {
+    ColorStop *stop = &g_array_index (pat->stops, ColorStop, i);
+    g_array_append_val (self->stops, *stop);
+  }
+}
+
+/*!
+ * \brief Get a good color to emulate the gradient with a solid fill
+ * \ingroup DiaPattern
+ */
+void
+dia_pattern_get_fallback_color (DiaPattern *self, Color *color)
+{
+  g_return_if_fail (self != NULL && color != NULL);
+  if (self->stops->len > 0)
+    *color = g_array_index (self->stops, ColorStop, 0).color;
+  else
+    *color = color_black;
+}
+
+/*!
+ * \brief Drop the reference count
+ * \ingroup DiaPattern
+ */
+void
+dia_pattern_release (DiaPattern *pattern)
+{
+  g_object_unref (pattern);
+}
+
+/*!
+ * \brief Call the given callback for each color stop
+ * \ingroup DiaPattern
+ */
+void
+dia_pattern_foreach (DiaPattern *pattern, DiaColorStopFunc fn, gpointer user_data)
+{
+  gsize i;
+  g_return_if_fail (pattern != NULL && fn != NULL);
+
+  for (i = 0; i < pattern->stops->len; ++i) {
+    ColorStop *stop = &g_array_index (pattern->stops, ColorStop, i);
+
+    (*fn)(stop->offset, &stop->color, user_data);
+  }
+}
diff --git a/lib/pattern.h b/lib/pattern.h
new file mode 100644
index 0000000..0815f1b
--- /dev/null
+++ b/lib/pattern.h
@@ -0,0 +1,63 @@
+/* Dia -- an diagram creation/manipulation program
+ * Copyright (C) 1998 Alexander Larsson
+ *
+ * pattern.h - interface definition for DiaPattern object
+ * Copyright (C) 2013 Hans Breuer
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+#ifndef PATTERN_H
+#define PATTERN_H
+ 
+#include "diatypes.h"
+#include "geometry.h"
+#include <glib.h>
+
+G_BEGIN_DECLS
+
+typedef enum
+{
+  DIA_LINEAR_GRADIENT = 1,
+  DIA_RADIAL_GRADIENT
+} DiaPatternType;
+
+typedef enum
+{
+  DIA_PATTERN_USER_SPACE     = (1<<0),
+  DIA_PATTERN_EXTEND_REPEAT  = (1<<1),
+  DIA_PATTERN_EXTEND_REFLECT = (1<<2),
+  DIA_PATTERN_EXTEND_PAD     = (1<<3)
+} DiaPatternFlags;
+
+DiaPattern *dia_pattern_new (DiaPatternType pt, guint flags, real x, real y);
+
+void dia_pattern_set_radius (DiaPattern *self, real r);
+void dia_pattern_set_point (DiaPattern *pattern, real x, real y); 
+void dia_pattern_add_color (DiaPattern *pattern, real pos, const Color *stop);
+void dia_pattern_set_pattern (DiaPattern *pattern, DiaPattern *pat);
+
+void dia_pattern_get_fallback_color (DiaPattern *pattern, Color *color);
+void dia_pattern_get_points (DiaPattern *pattern, Point *p1, Point *p2);
+void dia_pattern_get_radius (DiaPattern *pattern, real *r);
+void dia_pattern_get_settings (DiaPattern *pattern, DiaPatternType *type, guint *flags);
+
+typedef gboolean (*DiaColorStopFunc) (real ofs, const Color *col, gpointer user_data);
+void dia_pattern_foreach (DiaPattern *pattern, DiaColorStopFunc fn, gpointer user_data);
+
+void dia_pattern_release (DiaPattern *pattern);
+
+G_END_DECLS
+
+#endif /* PATTERN_H */