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+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2010 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, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "config.h"
+#include "gtkgradient.h"
+#include "gtkstyleproperties.h"
+#include "gtkintl.h"
+
+/**
+ * SECTION:gtkgradient
+ * @Short_description: Gradients
+ * @Title: GtkGradient
+ *
+ * GtkGradient is a boxed type that represents a gradient.
+ * It is the result of parsing a
+ * <link linkend="gtkcssprovider-gradients">gradient expression</link>.
+ * To obtain the gradient represented by a GtkGradient, it has to
+ * be resolved with gtk_gradient_resolve(), which replaces all
+ * symbolic color references by the colors they refer to (in a given
+ * context) and constructs a #cairo_pattern_t value.
+ *
+ * It is not normally necessary to deal directly with #GtkGradients,
+ * since they are mostly used behind the scenes by #GtkStyleContext and
+ * #GtkCssProvider.
+ */
+
+G_DEFINE_BOXED_TYPE (GtkGradient, gtk_gradient,
+ gtk_gradient_ref, gtk_gradient_unref)
+
+typedef struct ColorStop ColorStop;
+
+struct ColorStop
+{
+ gdouble offset;
+ GtkSymbolicColor *color;
+};
+
+struct _GtkGradient
+{
+ gdouble x0;
+ gdouble y0;
+ gdouble x1;
+ gdouble y1;
+ gdouble radius0;
+ gdouble radius1;
+
+ GArray *stops;
+
+ guint ref_count;
+};
+
+/**
+ * gtk_gradient_new_linear:
+ * @x0: X coordinate of the starting point
+ * @y0: Y coordinate of the starting point
+ * @x1: X coordinate of the end point
+ * @y1: Y coordinate of the end point
+ *
+ * Creates a new linear gradient along the line defined by (x0, y0) and (x1, y1). Before using the gradient
+ * a number of stop colors must be added through gtk_gradient_add_color_stop().
+ *
+ * Returns: A newly created #GtkGradient
+ *
+ * Since: 3.0
+ **/
+GtkGradient *
+gtk_gradient_new_linear (gdouble x0,
+ gdouble y0,
+ gdouble x1,
+ gdouble y1)
+{
+ GtkGradient *gradient;
+
+ gradient = g_slice_new (GtkGradient);
+ gradient->stops = g_array_new (FALSE, FALSE, sizeof (ColorStop));
+
+ gradient->x0 = x0;
+ gradient->y0 = y0;
+ gradient->x1 = x1;
+ gradient->y1 = y1;
+ gradient->radius0 = 0;
+ gradient->radius1 = 0;
+
+ gradient->ref_count = 1;
+
+ return gradient;
+}
+
+/**
+ * gtk_gradient_new_radial:
+ * @x0: X coordinate of the start circle
+ * @y0: Y coordinate of the start circle
+ * @radius0: radius of the start circle
+ * @x1: X coordinate of the end circle
+ * @y1: Y coordinate of the end circle
+ * @radius1: radius of the end circle
+ *
+ * Creates a new radial gradient along the two circles defined by (x0, y0, radius0) and
+ * (x1, y1, radius1). Before using the gradient a number of stop colors must be added
+ * through gtk_gradient_add_color_stop().
+ *
+ * Returns: A newly created #GtkGradient
+ *
+ * Since: 3.0
+ **/
+GtkGradient *
+gtk_gradient_new_radial (gdouble x0,
+ gdouble y0,
+ gdouble radius0,
+ gdouble x1,
+ gdouble y1,
+ gdouble radius1)
+{
+ GtkGradient *gradient;
+
+ gradient = g_slice_new (GtkGradient);
+ gradient->stops = g_array_new (FALSE, FALSE, sizeof (ColorStop));
+
+ gradient->x0 = x0;
+ gradient->y0 = y0;
+ gradient->x1 = x1;
+ gradient->y1 = y1;
+ gradient->radius0 = radius0;
+ gradient->radius1 = radius1;
+
+ gradient->ref_count = 1;
+
+ return gradient;
+}
+
+/**
+ * gtk_gradient_add_color_stop:
+ * @gradient: a #GtkGradient
+ * @offset: offset for the color stop
+ * @color: color to use
+ *
+ * Adds a stop color to @gradient.
+ *
+ * Since: 3.0
+ **/
+void
+gtk_gradient_add_color_stop (GtkGradient *gradient,
+ gdouble offset,
+ GtkSymbolicColor *color)
+{
+ ColorStop stop;
+
+ g_return_if_fail (gradient != NULL);
+
+ stop.offset = offset;
+ stop.color = gtk_symbolic_color_ref (color);
+
+ g_array_append_val (gradient->stops, stop);
+}
+
+/**
+ * gtk_gradient_ref:
+ * @gradient: a #GtkGradient
+ *
+ * Increases the reference count of @gradient.
+ *
+ * Returns: The same @gradient
+ *
+ * Since: 3.0
+ **/
+GtkGradient *
+gtk_gradient_ref (GtkGradient *gradient)
+{
+ g_return_val_if_fail (gradient != NULL, NULL);
+
+ gradient->ref_count++;
+
+ return gradient;
+}
+
+/**
+ * gtk_gradient_unref:
+ * @gradient: a #GtkGradient
+ *
+ * Decreases the reference count of @gradient, freeing its memory
+ * if the reference count reaches 0.
+ *
+ * Since: 3.0
+ **/
+void
+gtk_gradient_unref (GtkGradient *gradient)
+{
+ g_return_if_fail (gradient != NULL);
+
+ gradient->ref_count--;
+
+ if (gradient->ref_count == 0)
+ {
+ guint i;
+
+ for (i = 0; i < gradient->stops->len; i++)
+ {
+ ColorStop *stop;
+
+ stop = &g_array_index (gradient->stops, ColorStop, i);
+ gtk_symbolic_color_unref (stop->color);
+ }
+
+ g_array_free (gradient->stops, TRUE);
+ g_slice_free (GtkGradient, gradient);
+ }
+}
+
+/**
+ * gtk_gradient_resolve:
+ * @gradient: a #GtkGradient
+ * @props: #GtkStyleProperties to use when resolving named colors
+ * @resolved_gradient: (out): return location for the resolved pattern
+ *
+ * If @gradient is resolvable, @resolved_gradient will be filled in
+ * with the resolved gradient as a cairo_pattern_t, and %TRUE will
+ * be returned. Generally, if @gradient can't be resolved, it is
+ * due to it being defined on top of a named color that doesn't
+ * exist in @props.
+ *
+ * Returns: %TRUE if the gradient has been resolved
+ *
+ * Since: 3.0
+ **/
+gboolean
+gtk_gradient_resolve (GtkGradient *gradient,
+ GtkStyleProperties *props,
+ cairo_pattern_t **resolved_gradient)
+{
+ cairo_pattern_t *pattern;
+ guint i;
+
+ g_return_val_if_fail (gradient != NULL, FALSE);
+ g_return_val_if_fail (GTK_IS_STYLE_PROPERTIES (props), FALSE);
+ g_return_val_if_fail (resolved_gradient != NULL, FALSE);
+
+ if (gradient->radius0 == 0 && gradient->radius1 == 0)
+ pattern = cairo_pattern_create_linear (gradient->x0, gradient->y0,
+ gradient->x1, gradient->y1);
+ else
+ pattern = cairo_pattern_create_radial (gradient->x0, gradient->y0,
+ gradient->radius0,
+ gradient->x1, gradient->y1,
+ gradient->radius1);
+
+ for (i = 0; i < gradient->stops->len; i++)
+ {
+ ColorStop *stop;
+ GdkRGBA color;
+
+ stop = &g_array_index (gradient->stops, ColorStop, i);
+
+ if (!gtk_symbolic_color_resolve (stop->color, props, &color))
+ {
+ cairo_pattern_destroy (pattern);
+ return FALSE;
+ }
+
+ cairo_pattern_add_color_stop_rgba (pattern, stop->offset,
+ color.red, color.green,
+ color.blue, color.alpha);
+ }
+
+ *resolved_gradient = pattern;
+ return TRUE;
+}