[gimp] app: allow to show an arbitrary number of "background curves"

[Michael Natterer <mitch src gnome org>]

commit 2352037dbdf059450f9be0095bc7badd964e47c0
Author: Michael Natterer <mitch gimp org>
Date:   Sat Feb 20 20:31:22 2010 +0100

    app: allow to show an arbitrary number of "background curves"
    
    which are drawn with a configurable color at 50% opacity.

 app/widgets/gimpcurveview.c |  129 +++++++++++++++++++++++++++++++++++++------
 app/widgets/gimpcurveview.h |   26 ++++++---
 2 files changed, 129 insertions(+), 26 deletions(-)
---
diff --git a/app/widgets/gimpcurveview.c b/app/widgets/gimpcurveview.c
index cdf7b54..d132acc 100644
--- a/app/widgets/gimpcurveview.c
+++ b/app/widgets/gimpcurveview.c
@@ -54,6 +54,13 @@ enum
 };
 
 
+typedef struct
+{
+  GimpCurve *curve;
+  GimpRGB    color;
+} BGCurve;
+
+
 static void       gimp_curve_view_finalize        (GObject          *object);
 static void       gimp_curve_view_dispose         (GObject          *object);
 static void       gimp_curve_view_set_property    (GObject          *object,
@@ -233,6 +240,13 @@ gimp_curve_view_dispose (GObject *object)
 
   gimp_curve_view_set_curve (view, NULL);
 
+  while (view->bg_curves)
+    {
+      BGCurve *bg = view->bg_curves->data;
+
+      gimp_curve_view_remove_background (view, bg->curve);
+    }
+
   G_OBJECT_CLASS (parent_class)->dispose (object);
 }
 
@@ -405,6 +419,37 @@ gimp_curve_view_draw_point (GimpCurveView *view,
              0, 2 * G_PI);
 }
 
+static void
+gimp_curve_view_draw_curve (GimpCurveView *view,
+                            cairo_t       *cr,
+                            GimpCurve     *curve,
+                            gint           width,
+                            gint           height,
+                            gint           border)
+{
+  gdouble x, y;
+  gint    i;
+
+  x = 0.0;
+  y = 1.0 - gimp_curve_map_value (curve, 0.0);
+
+  cairo_move_to (cr,
+                 border + (gdouble) width  * x,
+                 border + (gdouble) height * y);
+
+  for (i = 1; i < 256; i++)
+    {
+      x = (gdouble) i / 255.0;
+      y = 1.0 - gimp_curve_map_value (curve, x);
+
+      cairo_line_to (cr,
+                     border + (gdouble) width  * x,
+                     border + (gdouble) height * y);
+    }
+
+  cairo_stroke (cr);
+}
+
 static gboolean
 gimp_curve_view_expose (GtkWidget      *widget,
                         GdkEventExpose *event)
@@ -414,6 +459,7 @@ gimp_curve_view_expose (GtkWidget      *widget,
   GtkStyle      *style  = gtk_widget_get_style (widget);
   GtkAllocation  allocation;
   cairo_t       *cr;
+  GList         *list;
   gint           border;
   gint           width;
   gint           height;
@@ -467,28 +513,28 @@ gimp_curve_view_expose (GtkWidget      *widget,
   /*  Draw the grid lines  */
   gimp_curve_view_draw_grid (view, style, cr, width, height, border);
 
-  /*  Draw the curve  */
-  gdk_cairo_set_source_color (cr, &style->text[GTK_STATE_NORMAL]);
-
-  x = 0.0;
-  y = 1.0 - gimp_curve_map_value (view->curve, 0.0);
-
-  cairo_move_to (cr,
-                 border + (gdouble) width  * x,
-                 border + (gdouble) height * y);
-
-  for (i = 1; i < 256; i++)
+  /*  Draw the background curves  */
+  for (list = view->bg_curves; list; list = g_list_next (list))
     {
-      x = (gdouble) i / 255.0;
-      y = 1.0 - gimp_curve_map_value (view->curve, x);
+      BGCurve *bg = list->data;
 
-      cairo_line_to (cr,
-                     border + (gdouble) width  * x,
-                     border + (gdouble) height * y);
+      cairo_set_source_rgba (cr,
+                             bg->color.r,
+                             bg->color.g,
+                             bg->color.b,
+                             0.5);
+
+      gimp_curve_view_draw_curve (view, cr, bg->curve,
+                                  width, height, border);
     }
 
-  cairo_stroke (cr);
+  /*  Draw the curve  */
+  gdk_cairo_set_source_color (cr, &style->text[GTK_STATE_NORMAL]);
+
+  gimp_curve_view_draw_curve (view, cr, view->curve,
+                              width, height, border);
 
+  /*  Draw the points  */
   if (gimp_curve_get_curve_type (view->curve) == GIMP_CURVE_SMOOTH)
     {
       gdk_cairo_set_source_color (cr, &style->text[GTK_STATE_NORMAL]);
@@ -1059,6 +1105,55 @@ gimp_curve_view_get_curve (GimpCurveView *view)
 }
 
 void
+gimp_curve_view_add_background (GimpCurveView *view,
+                                GimpCurve     *curve,
+                                const GimpRGB *color)
+{
+  BGCurve *bg;
+
+  g_return_if_fail (GIMP_IS_CURVE_VIEW (view));
+  g_return_if_fail (GIMP_IS_CURVE (curve));
+  g_return_if_fail (color != NULL);
+
+  bg = g_slice_new0 (BGCurve);
+
+  bg->curve = g_object_ref (curve);
+  bg->color = *color;
+
+  view->bg_curves = g_list_append (view->bg_curves, bg);
+
+  gtk_widget_queue_draw (GTK_WIDGET (view));
+}
+
+void
+gimp_curve_view_remove_background (GimpCurveView *view,
+                                   GimpCurve     *curve)
+{
+  GList *list;
+
+  g_return_if_fail (GIMP_IS_CURVE_VIEW (view));
+  g_return_if_fail (GIMP_IS_CURVE (curve));
+
+  for (list = view->bg_curves; list; list = g_list_next (list))
+    {
+      BGCurve *bg = list->data;
+
+      if (bg->curve == curve)
+        {
+          g_object_unref (bg->curve);
+
+          view->bg_curves = g_list_remove (view->bg_curves, bg);
+
+          g_slice_free (BGCurve, bg);
+
+          gtk_widget_queue_draw (GTK_WIDGET (view));
+
+          break;
+        }
+    }
+}
+
+void
 gimp_curve_view_set_selected (GimpCurveView *view,
                               gint           selected)
 {
diff --git a/app/widgets/gimpcurveview.h b/app/widgets/gimpcurveview.h
index 98df87c..b313d53 100644
--- a/app/widgets/gimpcurveview.h
+++ b/app/widgets/gimpcurveview.h
@@ -40,6 +40,8 @@ struct _GimpCurveView
 
   GimpCurve         *curve;
 
+  GList             *bg_curves;
+
   gboolean           draw_base_line;
   gint               grid_rows;
   gint               grid_columns;
@@ -72,18 +74,24 @@ struct _GimpCurveViewClass
 };
 
 
-GType       gimp_curve_view_get_type     (void) G_GNUC_CONST;
+GType       gimp_curve_view_get_type          (void) G_GNUC_CONST;
+
+GtkWidget * gimp_curve_view_new               (void);
 
-GtkWidget * gimp_curve_view_new          (void);
+void        gimp_curve_view_set_curve         (GimpCurveView *view,
+                                               GimpCurve     *curve);
+GimpCurve * gimp_curve_view_get_curve         (GimpCurveView *view);
 
-void        gimp_curve_view_set_curve    (GimpCurveView *view,
-                                          GimpCurve     *curve);
-GimpCurve * gimp_curve_view_get_curve    (GimpCurveView *view);
+void        gimp_curve_view_add_background    (GimpCurveView *view,
+                                               GimpCurve     *curve,
+                                               const GimpRGB *color);
+void        gimp_curve_view_remove_background (GimpCurveView *view,
+                                               GimpCurve     *curve);
 
-void        gimp_curve_view_set_selected (GimpCurveView *view,
-                                          gint           selected);
-void        gimp_curve_view_set_xpos     (GimpCurveView *view,
-                                          gdouble        x);
+void        gimp_curve_view_set_selected      (GimpCurveView *view,
+                                               gint           selected);
+void        gimp_curve_view_set_xpos          (GimpCurveView *view,
+                                               gdouble        x);
 
 
 #endif /* __GIMP_CURVE_VIEW_H__ */