app: add "gboolean gamma_corrected" to gimp_histogram_new()

so we can make histograms of the gamma-corrected image data. Pass
TRUE all over the place so the histogram works perceptually. This
needs more thinking...

app/core/gimpdrawable-equalize.c

@@ -40,7 +40,7 @@ gimp_drawable_equalize (GimpDrawable *drawable,
   g_return_if_fail (GIMP_IS_DRAWABLE (drawable));
   g_return_if_fail (gimp_item_is_attached (GIMP_ITEM (drawable)));
 
-  hist = gimp_histogram_new ();
+  hist = gimp_histogram_new (TRUE);
   gimp_drawable_calculate_histogram (drawable, hist);
 
   equalize = gegl_node_new_child (NULL,

app/core/gimpdrawable-levels.c

@@ -52,7 +52,7 @@ gimp_drawable_levels_stretch (GimpDrawable *drawable,
 
   config = g_object_new (GIMP_TYPE_LEVELS_CONFIG, NULL);
 
-  histogram = gimp_histogram_new ();
+  histogram = gimp_histogram_new (TRUE);
   gimp_drawable_calculate_histogram (drawable, histogram);
 
   gimp_levels_config_stretch (config, histogram,

app/core/gimphistogram.c

@@ -42,6 +42,7 @@ enum
 
 struct _GimpHistogramPrivate
 {
+  gboolean gamma_correct;
   gint     n_channels;
   gint     n_bins;
   gdouble *values;
@@ -185,9 +186,13 @@ gimp_histogram_get_memsize (GimpObject *object,
 /*  public functions  */
 
 GimpHistogram *
-gimp_histogram_new (void)
+gimp_histogram_new (gboolean gamma_correct)
 {
-  return g_object_new (GIMP_TYPE_HISTOGRAM, NULL);
+  GimpHistogram *histogram = g_object_new (GIMP_TYPE_HISTOGRAM, NULL);
+
+  histogram->priv->gamma_correct = gamma_correct;
+
+  return histogram;
 }
 
 /**
@@ -206,7 +211,7 @@ gimp_histogram_duplicate (GimpHistogram *histogram)
 
   g_return_val_if_fail (GIMP_IS_HISTOGRAM (histogram), NULL);
 
-  dup = gimp_histogram_new ();
+  dup = gimp_histogram_new (histogram->priv->gamma_correct);
 
   dup->priv->n_channels = histogram->priv->n_channels;
   dup->priv->n_bins     = histogram->priv->n_bins;
@@ -257,7 +262,10 @@ gimp_histogram_calculate (GimpHistogram       *histogram,
 
       if (model == babl_model ("Y"))
         {
-          format = babl_format ("Y float");
+          if (priv->gamma_correct)
+            format = babl_format ("Y' float");
+          else
+            format = babl_format ("Y float");
         }
       else if (model == babl_model ("Y'"))
         {
@@ -265,7 +273,10 @@ gimp_histogram_calculate (GimpHistogram       *histogram,
         }
       else if (model == babl_model ("YA"))
         {
-          format = babl_format ("YA float");
+          if (priv->gamma_correct)
+            format = babl_format ("Y'A float");
+          else
+            format = babl_format ("YA float");
         }
       else if (model == babl_model ("Y'A"))
         {
@@ -273,7 +284,10 @@ gimp_histogram_calculate (GimpHistogram       *histogram,
         }
       else if (model == babl_model ("RGB"))
         {
-          format = babl_format ("RGB float");
+          if (priv->gamma_correct)
+            format = babl_format ("R'G'B' float");
+          else
+            format = babl_format ("RGB float");
         }
       else if (model == babl_model ("R'G'B'"))
         {
@@ -281,7 +295,10 @@ gimp_histogram_calculate (GimpHistogram       *histogram,
         }
       else if (model == babl_model ("RGBA"))
         {
-          format = babl_format ("RGBA float");
+          if (priv->gamma_correct)
+            format = babl_format ("R'G'B'A float");
+          else
+            format = babl_format ("RGBA float");
         }
       else if (model == babl_model ("R'G'B'A"))
         {

app/core/gimphistogram.h

@@ -50,7 +50,7 @@ struct _GimpHistogramClass
 
 GType           gimp_histogram_get_type      (void) G_GNUC_CONST;
 
-GimpHistogram * gimp_histogram_new           (void);
+GimpHistogram * gimp_histogram_new           (gboolean              gamma_correct);
 
 GimpHistogram * gimp_histogram_duplicate     (GimpHistogram        *histogram);
 

app/pdb/color-cmds.c

@@ -623,7 +623,7 @@ histogram_invoker (GimpProcedure         *procedure,
 
       if (success)
         {
-          GimpHistogram *histogram = gimp_histogram_new ();
+          GimpHistogram *histogram = gimp_histogram_new (TRUE);
 
           gimp_drawable_calculate_histogram (drawable, histogram);
 

app/tools/gimpcurvestool.c

@@ -212,7 +212,7 @@ gimp_curves_tool_initialize (GimpTool     *tool,
   gimp_int_combo_box_set_sensitivity (GIMP_INT_COMBO_BOX (c_tool->channel_menu),
                                       curves_menu_sensitivity, drawable, NULL);
 
-  histogram = gimp_histogram_new ();
+  histogram = gimp_histogram_new (TRUE);
   gimp_drawable_calculate_histogram (drawable, histogram);
   gimp_histogram_view_set_background (GIMP_HISTOGRAM_VIEW (c_tool->graph),
                                       histogram);

app/tools/gimplevelstool.c

@@ -177,7 +177,7 @@ gimp_levels_tool_class_init (GimpLevelsToolClass *klass)
 static void
 gimp_levels_tool_init (GimpLevelsTool *tool)
 {
-  tool->histogram = gimp_histogram_new ();
+  tool->histogram = gimp_histogram_new (TRUE);
 }
 
 static void

app/tools/gimpthresholdtool.c

@@ -116,7 +116,7 @@ gimp_threshold_tool_class_init (GimpThresholdToolClass *klass)
 static void
 gimp_threshold_tool_init (GimpThresholdTool *t_tool)
 {
-  t_tool->histogram = gimp_histogram_new ();
+  t_tool->histogram = gimp_histogram_new (TRUE);
 }
 
 static void

app/widgets/gimphistogrameditor.c

@@ -280,7 +280,7 @@ gimp_histogram_editor_set_image (GimpImageEditor *image_editor,
 
   if (image)
     {
-      editor->histogram = gimp_histogram_new ();
+      editor->histogram = gimp_histogram_new (TRUE);
 
       gimp_histogram_view_set_histogram (view, editor->histogram);