Adding upstream version 2.10.36.upstream/2.10.36

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1055 insertions, 0 deletions

diff --git a/app/tools/gimplevelstool.c b/app/tools/gimplevelstool.c
new file mode 100644
index 0000000..4e97f71
--- /dev/null
+++ b/app/tools/gimplevelstool.c
@@ -0,0 +1,1055 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * 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 3 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, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gegl.h>
+#include <gtk/gtk.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+#include "libgimpconfig/gimpconfig.h"
+#include "libgimpwidgets/gimpwidgets.h"
+
+#include "tools-types.h"
+
+#include "gegl/gimp-babl.h"
+
+#include "operations/gimplevelsconfig.h"
+#include "operations/gimpoperationlevels.h"
+
+#include "core/gimp-gui.h"
+#include "core/gimpasync.h"
+#include "core/gimpcancelable.h"
+#include "core/gimpdrawable.h"
+#include "core/gimpdrawable-histogram.h"
+#include "core/gimperror.h"
+#include "core/gimphistogram.h"
+#include "core/gimpimage.h"
+#include "core/gimptoolinfo.h"
+#include "core/gimptriviallycancelablewaitable.h"
+#include "core/gimpwaitable.h"
+
+#include "widgets/gimpcolorbar.h"
+#include "widgets/gimphandlebar.h"
+#include "widgets/gimphelp-ids.h"
+#include "widgets/gimphistogramview.h"
+#include "widgets/gimppropwidgets.h"
+#include "widgets/gimpwidgets-constructors.h"
+
+#include "display/gimpdisplay.h"
+
+#include "gimphistogramoptions.h"
+#include "gimplevelstool.h"
+
+#include "gimp-intl.h"
+
+
+#define PICK_LOW_INPUT    (1 << 0)
+#define PICK_GAMMA        (1 << 1)
+#define PICK_HIGH_INPUT   (1 << 2)
+#define PICK_ALL_CHANNELS (1 << 8)
+
+#define HISTOGRAM_WIDTH    256
+#define GRADIENT_HEIGHT     12
+#define CONTROL_HEIGHT      10
+
+
+/*  local function prototypes  */
+
+static void       gimp_levels_tool_finalize       (GObject          *object);
+
+static gboolean   gimp_levels_tool_initialize     (GimpTool         *tool,
+                                                   GimpDisplay      *display,
+                                                   GError          **error);
+
+static gchar    * gimp_levels_tool_get_operation  (GimpFilterTool   *filter_tool,
+                                                   gchar           **description);
+static void       gimp_levels_tool_dialog         (GimpFilterTool   *filter_tool);
+static void       gimp_levels_tool_reset          (GimpFilterTool   *filter_tool);
+static void       gimp_levels_tool_config_notify  (GimpFilterTool   *filter_tool,
+                                                   GimpConfig       *config,
+                                                   const GParamSpec *pspec);
+static gboolean   gimp_levels_tool_settings_import(GimpFilterTool   *filter_tool,
+                                                   GInputStream     *input,
+                                                   GError          **error);
+static gboolean   gimp_levels_tool_settings_export(GimpFilterTool   *filter_tool,
+                                                   GOutputStream    *output,
+                                                   GError          **error);
+static void       gimp_levels_tool_color_picked   (GimpFilterTool   *filter_tool,
+                                                   gpointer          identifier,
+                                                   gdouble           x,
+                                                   gdouble           y,
+                                                   const Babl       *sample_format,
+                                                   const GimpRGB    *color);
+
+static void       gimp_levels_tool_export_setup   (GimpSettingsBox  *settings_box,
+                                                   GtkFileChooserDialog *dialog,
+                                                   gboolean          export,
+                                                   GimpLevelsTool   *tool);
+
+static void       levels_update_input_bar         (GimpLevelsTool   *tool);
+
+static void       levels_channel_callback         (GtkWidget        *widget,
+                                                   GimpFilterTool   *filter_tool);
+static void       levels_channel_reset_callback   (GtkWidget        *widget,
+                                                   GimpFilterTool   *filter_tool);
+
+static gboolean   levels_menu_sensitivity         (gint              value,
+                                                   gpointer          data);
+
+static void       levels_stretch_callback         (GtkWidget        *widget,
+                                                   GimpLevelsTool   *tool);
+static void       levels_linear_gamma_changed     (GtkAdjustment    *adjustment,
+                                                   GimpLevelsTool   *tool);
+
+static void       levels_to_curves_callback       (GtkWidget        *widget,
+                                                   GimpFilterTool   *filter_tool);
+
+
+G_DEFINE_TYPE (GimpLevelsTool, gimp_levels_tool, GIMP_TYPE_FILTER_TOOL)
+
+#define parent_class gimp_levels_tool_parent_class
+
+
+void
+gimp_levels_tool_register (GimpToolRegisterCallback  callback,
+                           gpointer                  data)
+{
+  (* callback) (GIMP_TYPE_LEVELS_TOOL,
+                GIMP_TYPE_HISTOGRAM_OPTIONS,
+                gimp_color_options_gui,
+                0,
+                "gimp-levels-tool",
+                _("Levels"),
+                _("Adjust color levels"),
+                N_("_Levels..."), NULL,
+                NULL, GIMP_HELP_TOOL_LEVELS,
+                GIMP_ICON_TOOL_LEVELS,
+                data);
+}
+
+static void
+gimp_levels_tool_class_init (GimpLevelsToolClass *klass)
+{
+  GObjectClass        *object_class      = G_OBJECT_CLASS (klass);
+  GimpToolClass       *tool_class        = GIMP_TOOL_CLASS (klass);
+  GimpFilterToolClass *filter_tool_class = GIMP_FILTER_TOOL_CLASS (klass);
+
+  object_class->finalize             = gimp_levels_tool_finalize;
+
+  tool_class->initialize             = gimp_levels_tool_initialize;
+
+  filter_tool_class->get_operation   = gimp_levels_tool_get_operation;
+  filter_tool_class->dialog          = gimp_levels_tool_dialog;
+  filter_tool_class->reset           = gimp_levels_tool_reset;
+  filter_tool_class->config_notify   = gimp_levels_tool_config_notify;
+  filter_tool_class->settings_import = gimp_levels_tool_settings_import;
+  filter_tool_class->settings_export = gimp_levels_tool_settings_export;
+  filter_tool_class->color_picked    = gimp_levels_tool_color_picked;
+}
+
+static void
+gimp_levels_tool_init (GimpLevelsTool *tool)
+{
+}
+
+static void
+gimp_levels_tool_finalize (GObject *object)
+{
+  GimpLevelsTool *tool = GIMP_LEVELS_TOOL (object);
+
+  g_clear_object (&tool->histogram);
+  g_clear_object (&tool->histogram_async);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static gboolean
+gimp_levels_tool_initialize (GimpTool     *tool,
+                             GimpDisplay  *display,
+                             GError      **error)
+{
+  GimpFilterTool   *filter_tool = GIMP_FILTER_TOOL (tool);
+  GimpLevelsTool   *l_tool      = GIMP_LEVELS_TOOL (tool);
+  GimpImage        *image       = gimp_display_get_image (display);
+  GimpDrawable     *drawable    = gimp_image_get_active_drawable (image);
+  GimpLevelsConfig *config;
+  gdouble           scale_factor;
+  gdouble           step_increment;
+  gdouble           page_increment;
+  gint              digits;
+
+  if (! GIMP_TOOL_CLASS (parent_class)->initialize (tool, display, error))
+    {
+      return FALSE;
+    }
+
+  config = GIMP_LEVELS_CONFIG (filter_tool->config);
+
+  g_clear_object (&l_tool->histogram);
+  g_clear_object (&l_tool->histogram_async);
+  l_tool->histogram = gimp_histogram_new (config->linear);
+
+  l_tool->histogram_async = gimp_drawable_calculate_histogram_async (
+    drawable, l_tool->histogram, FALSE);
+  gimp_histogram_view_set_histogram (GIMP_HISTOGRAM_VIEW (l_tool->histogram_view),
+                                     l_tool->histogram);
+
+  if (gimp_drawable_get_component_type (drawable) == GIMP_COMPONENT_TYPE_U8)
+    {
+      scale_factor   = 255.0;
+      step_increment = 1.0;
+      page_increment = 8.0;
+      digits         = 0;
+    }
+  else
+    {
+      scale_factor   = 100;
+      step_increment = 0.01;
+      page_increment = 1.0;
+      digits         = 2;
+    }
+
+  gimp_prop_widget_set_factor (l_tool->low_input_spinbutton,
+                               scale_factor, step_increment, page_increment,
+                               digits);
+  gimp_prop_widget_set_factor (l_tool->high_input_spinbutton,
+                               scale_factor, step_increment, page_increment,
+                               digits);
+  gimp_prop_widget_set_factor (l_tool->low_output_spinbutton,
+                               scale_factor, step_increment, page_increment,
+                               digits);
+  gimp_prop_widget_set_factor (l_tool->high_output_spinbutton,
+                               scale_factor, step_increment, page_increment,
+                               digits);
+
+  gtk_adjustment_configure (l_tool->gamma_linear,
+                            scale_factor / 2.0,
+                            0, scale_factor, 0.1, 1.0, 0);
+
+  return TRUE;
+}
+
+static gchar *
+gimp_levels_tool_get_operation (GimpFilterTool  *filter_tool,
+                                gchar          **description)
+{
+  *description = g_strdup (_("Adjust Color Levels"));
+
+  return g_strdup ("gimp:levels");
+}
+
+
+/*******************/
+/*  Levels dialog  */
+/*******************/
+
+static GtkWidget *
+gimp_levels_tool_color_picker_new (GimpLevelsTool *tool,
+                                   guint           value)
+{
+  const gchar *icon_name;
+  const gchar *help;
+  gboolean     all_channels = (value & PICK_ALL_CHANNELS) != 0;
+
+  switch (value & 0xF)
+    {
+    case PICK_LOW_INPUT:
+      icon_name = GIMP_ICON_COLOR_PICKER_BLACK;
+
+      if (all_channels)
+        help = _("Pick black point for all channels");
+      else
+        help = _("Pick black point for the selected channel");
+      break;
+
+    case PICK_GAMMA:
+      icon_name = GIMP_ICON_COLOR_PICKER_GRAY;
+
+      if (all_channels)
+        help = _("Pick gray point for all channels");
+      else
+        help = _("Pick gray point for the selected channel");
+      break;
+
+    case PICK_HIGH_INPUT:
+      icon_name = GIMP_ICON_COLOR_PICKER_WHITE;
+
+      if (all_channels)
+        help = _("Pick white point for all channels");
+      else
+        help = _("Pick white point for the selected channel");
+      break;
+
+    default:
+      return NULL;
+    }
+
+  return gimp_filter_tool_add_color_picker (GIMP_FILTER_TOOL (tool),
+                                            GUINT_TO_POINTER (value),
+                                            icon_name,
+                                            help,
+                                            /* pick_abyss = */ FALSE,
+                                            NULL, NULL);
+}
+
+static void
+gimp_levels_tool_dialog (GimpFilterTool *filter_tool)
+{
+  GimpLevelsTool   *tool         = GIMP_LEVELS_TOOL (filter_tool);
+  GimpToolOptions  *tool_options = GIMP_TOOL_GET_OPTIONS (filter_tool);
+  GimpLevelsConfig *config       = GIMP_LEVELS_CONFIG (filter_tool->config);
+  GtkListStore     *store;
+  GtkWidget        *main_vbox;
+  GtkWidget        *frame_vbox;
+  GtkWidget        *vbox;
+  GtkWidget        *vbox2;
+  GtkWidget        *vbox3;
+  GtkWidget        *hbox;
+  GtkWidget        *hbox2;
+  GtkWidget        *label;
+  GtkWidget        *main_frame;
+  GtkWidget        *frame;
+  GtkWidget        *button;
+  GtkWidget        *spinbutton;
+  GtkAdjustment    *adjustment;
+  GtkWidget        *bar;
+  GtkWidget        *handle_bar;
+  gint              border;
+
+  g_signal_connect (filter_tool->settings_box, "file-dialog-setup",
+                    G_CALLBACK (gimp_levels_tool_export_setup),
+                    filter_tool);
+
+  main_vbox = gimp_filter_tool_dialog_get_vbox (filter_tool);
+
+  /*  The combo box for selecting channels  */
+  main_frame = gimp_frame_new (NULL);
+  gtk_box_pack_start (GTK_BOX (main_vbox), main_frame, TRUE, TRUE, 0);
+  gtk_widget_show (main_frame);
+
+  hbox = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 6);
+  gtk_frame_set_label_widget (GTK_FRAME (main_frame), hbox);
+  gtk_widget_show (hbox);
+
+  label = gtk_label_new_with_mnemonic (_("Cha_nnel:"));
+  gimp_label_set_attributes (GTK_LABEL (label),
+                             PANGO_ATTR_WEIGHT, PANGO_WEIGHT_BOLD,
+                             -1);
+  gtk_box_pack_start (GTK_BOX (hbox), label, FALSE, FALSE, 0);
+  gtk_widget_show (label);
+
+  store = gimp_enum_store_new_with_range (GIMP_TYPE_HISTOGRAM_CHANNEL,
+                                          GIMP_HISTOGRAM_VALUE,
+                                          GIMP_HISTOGRAM_ALPHA);
+  tool->channel_menu =
+    gimp_enum_combo_box_new_with_model (GIMP_ENUM_STORE (store));
+  g_object_unref (store);
+
+  g_object_add_weak_pointer (G_OBJECT (tool->channel_menu),
+                             (gpointer) &tool->channel_menu);
+
+  gimp_enum_combo_box_set_icon_prefix (GIMP_ENUM_COMBO_BOX (tool->channel_menu),
+                                       "gimp-channel");
+  gimp_int_combo_box_set_sensitivity (GIMP_INT_COMBO_BOX (tool->channel_menu),
+                                      levels_menu_sensitivity, filter_tool, NULL);
+  gtk_box_pack_start (GTK_BOX (hbox), tool->channel_menu, FALSE, FALSE, 0);
+  gtk_widget_show (tool->channel_menu);
+
+  g_signal_connect (tool->channel_menu, "changed",
+                    G_CALLBACK (levels_channel_callback),
+                    tool);
+
+  gtk_label_set_mnemonic_widget (GTK_LABEL (label), tool->channel_menu);
+
+  button = gtk_button_new_with_mnemonic (_("R_eset Channel"));
+  gtk_box_pack_start (GTK_BOX (hbox), button, FALSE, FALSE, 0);
+  gtk_widget_show (button);
+
+  g_signal_connect (button, "clicked",
+                    G_CALLBACK (levels_channel_reset_callback),
+                    tool);
+
+  /*  The histogram scale radio buttons  */
+  hbox2 = gimp_prop_enum_icon_box_new (G_OBJECT (tool_options),
+                                       "histogram-scale", "gimp-histogram",
+                                       0, 0);
+  gtk_box_pack_end (GTK_BOX (hbox), hbox2, FALSE, FALSE, 0);
+  gtk_widget_show (hbox2);
+
+  /*  The linear/perceptual radio buttons  */
+  hbox2 = gimp_prop_boolean_icon_box_new (G_OBJECT (config),
+                                          "linear",
+                                          GIMP_ICON_COLOR_SPACE_LINEAR,
+                                          GIMP_ICON_COLOR_SPACE_PERCEPTUAL,
+                                          _("Adjust levels in linear light"),
+                                          _("Adjust levels perceptually"));
+  gtk_box_pack_end (GTK_BOX (hbox), hbox2, FALSE, FALSE, 0);
+  gtk_widget_show (hbox2);
+
+  frame_vbox = gtk_box_new (GTK_ORIENTATION_VERTICAL, 4);
+  gtk_container_add (GTK_CONTAINER (main_frame), frame_vbox);
+  gtk_widget_show (frame_vbox);
+
+  /*  Input levels frame  */
+  frame = gimp_frame_new (_("Input Levels"));
+  gtk_box_pack_start (GTK_BOX (frame_vbox), frame, TRUE, TRUE, 0);
+  gtk_widget_show (frame);
+
+  vbox = gtk_box_new (GTK_ORIENTATION_VERTICAL, 2);
+  gtk_container_add (GTK_CONTAINER (frame), vbox);
+  gtk_widget_show (vbox);
+
+  frame = gtk_frame_new (NULL);
+  gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
+  gtk_box_pack_start (GTK_BOX (vbox), frame, TRUE, TRUE, 0);
+  gtk_widget_show (frame);
+
+  vbox2 = gtk_box_new (GTK_ORIENTATION_VERTICAL, 0);
+  gtk_container_add (GTK_CONTAINER (frame), vbox2);
+  gtk_widget_show (vbox2);
+
+  tool->histogram_view = gimp_histogram_view_new (FALSE);
+
+  g_object_add_weak_pointer (G_OBJECT (tool->histogram_view),
+                             (gpointer) &tool->histogram_view);
+
+  gtk_box_pack_start (GTK_BOX (vbox2), tool->histogram_view, TRUE, TRUE, 0);
+  gtk_widget_show (GTK_WIDGET (tool->histogram_view));
+
+  g_object_bind_property (G_OBJECT (tool_options),         "histogram-scale",
+                          G_OBJECT (tool->histogram_view), "histogram-scale",
+                          G_BINDING_SYNC_CREATE |
+                          G_BINDING_BIDIRECTIONAL);
+
+  g_object_get (tool->histogram_view, "border-width", &border, NULL);
+
+  vbox3 = gtk_box_new (GTK_ORIENTATION_VERTICAL, 0);
+  gtk_container_set_border_width (GTK_CONTAINER (vbox3), border);
+  gtk_box_pack_start (GTK_BOX (vbox2), vbox3, FALSE, FALSE, 0);
+  gtk_widget_show (vbox3);
+
+  tool->input_bar = g_object_new (GIMP_TYPE_COLOR_BAR, NULL);
+  gtk_widget_set_size_request (tool->input_bar, -1, GRADIENT_HEIGHT / 2);
+  gtk_box_pack_start (GTK_BOX (vbox3), tool->input_bar, FALSE, FALSE, 0);
+  gtk_widget_show (tool->input_bar);
+
+  bar = g_object_new (GIMP_TYPE_COLOR_BAR, NULL);
+  gtk_widget_set_size_request (bar, -1, GRADIENT_HEIGHT / 2);
+  gtk_box_pack_start (GTK_BOX (vbox3), bar, FALSE, FALSE, 0);
+  gtk_widget_show (bar);
+
+  handle_bar = g_object_new (GIMP_TYPE_HANDLE_BAR, NULL);
+  gtk_widget_set_size_request (handle_bar, -1, CONTROL_HEIGHT);
+  gtk_box_pack_start (GTK_BOX (vbox3), handle_bar, FALSE, FALSE, 0);
+  gtk_widget_show (handle_bar);
+
+  gimp_handle_bar_connect_events (GIMP_HANDLE_BAR (handle_bar),
+                                  tool->input_bar);
+  gimp_handle_bar_connect_events (GIMP_HANDLE_BAR (handle_bar),
+                                  bar);
+
+  /*  Horizontal box for input levels spinbuttons  */
+  hbox = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 6);
+  gtk_box_pack_start (GTK_BOX (vbox), hbox, FALSE, FALSE, 0);
+  gtk_widget_show (hbox);
+
+  /*  low input spin  */
+  hbox2 = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 2);
+  gtk_box_pack_start (GTK_BOX (hbox), hbox2, FALSE, FALSE, 0);
+  gtk_widget_show (hbox2);
+
+  button = gimp_levels_tool_color_picker_new (tool, PICK_LOW_INPUT);
+  gtk_box_pack_start (GTK_BOX (hbox2), button, FALSE, FALSE, 0);
+  gtk_widget_show (button);
+
+  tool->low_input_spinbutton = spinbutton =
+    gimp_prop_spin_button_new (filter_tool->config, "low-input",
+                               0.01, 0.1, 1);
+  gtk_box_pack_start (GTK_BOX (hbox2), spinbutton, FALSE, FALSE, 0);
+  gtk_widget_show (spinbutton);
+
+  tool->low_input = gtk_spin_button_get_adjustment (GTK_SPIN_BUTTON (spinbutton));
+  gimp_handle_bar_set_adjustment (GIMP_HANDLE_BAR (handle_bar), 0,
+                                  tool->low_input);
+
+  /*  clamp input toggle  */
+  hbox2 = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 2);
+  gtk_box_pack_start (GTK_BOX (hbox), hbox2, TRUE, FALSE, 0);
+  gtk_widget_show (hbox2);
+
+  button = gimp_prop_check_button_new (filter_tool->config, "clamp-input",
+                                       _("Clamp _input"));
+  gtk_box_pack_start (GTK_BOX (hbox2), button, FALSE, FALSE, 0);
+  gtk_widget_show (button);
+
+  /*  input gamma spin  */
+  spinbutton = gimp_prop_spin_button_new (filter_tool->config, "gamma",
+                                          0.01, 0.1, 2);
+  gtk_box_pack_start (GTK_BOX (hbox2), spinbutton, FALSE, FALSE, 0);
+  gimp_help_set_help_data (spinbutton, _("Gamma"), NULL);
+  gtk_widget_show (spinbutton);
+
+  tool->gamma = gtk_spin_button_get_adjustment (GTK_SPIN_BUTTON (spinbutton));
+
+  tool->gamma_linear = GTK_ADJUSTMENT (gtk_adjustment_new (127, 0, 255,
+                                                           0.1, 1.0, 0.0));
+  g_signal_connect (tool->gamma_linear, "value-changed",
+                    G_CALLBACK (levels_linear_gamma_changed),
+                    tool);
+
+  gimp_handle_bar_set_adjustment (GIMP_HANDLE_BAR (handle_bar), 1,
+                                  tool->gamma_linear);
+  g_object_unref (tool->gamma_linear);
+
+  /*  high input spin  */
+  hbox2 = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 2);
+  gtk_box_pack_end (GTK_BOX (hbox), hbox2, FALSE, FALSE, 0);
+  gtk_widget_show (hbox2);
+
+  button = gimp_levels_tool_color_picker_new (tool, PICK_HIGH_INPUT);
+  gtk_box_pack_start (GTK_BOX (hbox2), button, FALSE, FALSE, 0);
+  gtk_widget_show (button);
+
+  spinbutton = gimp_prop_spin_button_new (filter_tool->config, "high-input",
+                                          0.01, 0.1, 1);
+  gtk_box_pack_start (GTK_BOX (hbox2), spinbutton, FALSE, FALSE, 0);
+  gtk_widget_show (spinbutton);
+  tool->high_input_spinbutton = spinbutton;
+
+  tool->high_input = gtk_spin_button_get_adjustment (GTK_SPIN_BUTTON (spinbutton));
+  gimp_handle_bar_set_adjustment (GIMP_HANDLE_BAR (handle_bar), 2,
+                                  tool->high_input);
+
+  /*  Output levels frame  */
+  frame = gimp_frame_new (_("Output Levels"));
+  gtk_box_pack_start (GTK_BOX (frame_vbox), frame, FALSE, FALSE, 0);
+  gtk_widget_show (frame);
+
+  vbox = gtk_box_new (GTK_ORIENTATION_VERTICAL, 4);
+  gtk_container_add (GTK_CONTAINER (frame), vbox);
+  gtk_widget_show (vbox);
+
+  frame = gtk_frame_new (NULL);
+  gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
+  gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
+  gtk_widget_show (frame);
+
+  vbox2 = gtk_box_new (GTK_ORIENTATION_VERTICAL, 0);
+  gtk_container_set_border_width (GTK_CONTAINER (vbox2), border);
+  gtk_container_add (GTK_CONTAINER (frame), vbox2);
+  gtk_widget_show (vbox2);
+
+  tool->output_bar = g_object_new (GIMP_TYPE_COLOR_BAR, NULL);
+  gtk_widget_set_size_request (tool->output_bar, -1, GRADIENT_HEIGHT);
+  gtk_box_pack_start (GTK_BOX (vbox2), tool->output_bar, FALSE, FALSE, 0);
+  gtk_widget_show (tool->output_bar);
+
+  handle_bar = g_object_new (GIMP_TYPE_HANDLE_BAR, NULL);
+  gtk_widget_set_size_request (handle_bar, -1, CONTROL_HEIGHT);
+  gtk_box_pack_start (GTK_BOX (vbox2), handle_bar, FALSE, FALSE, 0);
+  gtk_widget_show (handle_bar);
+
+  gimp_handle_bar_connect_events (GIMP_HANDLE_BAR (handle_bar),
+                                  tool->output_bar);
+
+  /*  Horizontal box for levels spin widgets  */
+  hbox = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 6);
+  gtk_box_pack_start (GTK_BOX (vbox), hbox, FALSE, FALSE, 0);
+  gtk_widget_show (hbox);
+
+  /*  low output spin  */
+  tool->low_output_spinbutton = spinbutton =
+    gimp_prop_spin_button_new (filter_tool->config, "low-output",
+                               0.01, 0.1, 1);
+  gtk_box_pack_start (GTK_BOX (hbox), spinbutton, FALSE, FALSE, 0);
+  gtk_widget_show (spinbutton);
+
+  adjustment = gtk_spin_button_get_adjustment (GTK_SPIN_BUTTON (spinbutton));
+  gimp_handle_bar_set_adjustment (GIMP_HANDLE_BAR (handle_bar), 0, adjustment);
+
+  /*  clamp output toggle  */
+  button = gimp_prop_check_button_new (filter_tool->config, "clamp-output",
+                                       _("Clamp outpu_t"));
+  gtk_box_pack_start (GTK_BOX (hbox), button, TRUE, FALSE, 0);
+  gtk_widget_show (button);
+
+  /*  high output spin  */
+  tool->high_output_spinbutton = spinbutton =
+    gimp_prop_spin_button_new (filter_tool->config, "high-output",
+                               0.01, 0.1, 1);
+  gtk_box_pack_end (GTK_BOX (hbox), spinbutton, FALSE, FALSE, 0);
+  gtk_widget_show (spinbutton);
+
+  adjustment = gtk_spin_button_get_adjustment (GTK_SPIN_BUTTON (spinbutton));
+  gimp_handle_bar_set_adjustment (GIMP_HANDLE_BAR (handle_bar), 2, adjustment);
+
+  /*  all channels frame  */
+  main_frame = gimp_frame_new (_("All Channels"));
+  gtk_box_pack_start (GTK_BOX (main_vbox), main_frame, FALSE, FALSE, 0);
+  gtk_widget_show (main_frame);
+
+  frame_vbox = gtk_box_new (GTK_ORIENTATION_VERTICAL, 4);
+  gtk_container_add (GTK_CONTAINER (main_frame), frame_vbox);
+  gtk_widget_show (frame_vbox);
+
+  hbox = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 6);
+  gtk_box_pack_start (GTK_BOX (frame_vbox), hbox, FALSE, FALSE, 0);
+  gtk_widget_show (hbox);
+
+  button = gtk_button_new_with_mnemonic (_("_Auto Input Levels"));
+  gtk_box_pack_start (GTK_BOX (hbox), button, FALSE, FALSE, 0);
+  gimp_help_set_help_data (button,
+                           _("Adjust levels for all channels automatically"),
+                           NULL);
+  gtk_widget_show (button);
+
+  g_signal_connect (button, "clicked",
+                    G_CALLBACK (levels_stretch_callback),
+                    tool);
+
+  button = gimp_levels_tool_color_picker_new (tool,
+                                              PICK_HIGH_INPUT |
+                                              PICK_ALL_CHANNELS);
+  gtk_box_pack_end (GTK_BOX (hbox), button, FALSE, FALSE, 0);
+  gtk_widget_show (button);
+
+  button = gimp_levels_tool_color_picker_new (tool,
+                                              PICK_GAMMA |
+                                              PICK_ALL_CHANNELS);
+  gtk_box_pack_end (GTK_BOX (hbox), button, FALSE, FALSE, 0);
+  gtk_widget_show (button);
+
+  button = gimp_levels_tool_color_picker_new (tool,
+                                              PICK_LOW_INPUT |
+                                              PICK_ALL_CHANNELS);
+  gtk_box_pack_end (GTK_BOX (hbox), button, FALSE, FALSE, 0);
+  gtk_widget_show (button);
+
+  button = gimp_icon_button_new (GIMP_ICON_TOOL_CURVES,
+                                 _("Edit these Settings as Curves"));
+  gtk_box_pack_start (GTK_BOX (main_vbox), button, FALSE, FALSE, 0);
+  gtk_widget_show (button);
+
+  g_signal_connect (button, "clicked",
+                    G_CALLBACK (levels_to_curves_callback),
+                    tool);
+
+  gimp_int_combo_box_set_active (GIMP_INT_COMBO_BOX (tool->channel_menu),
+                                 config->channel);
+}
+
+static void
+gimp_levels_tool_reset (GimpFilterTool *filter_tool)
+{
+  GimpHistogramChannel channel;
+
+  g_object_get (filter_tool->config,
+                "channel", &channel,
+                NULL);
+
+  GIMP_FILTER_TOOL_CLASS (parent_class)->reset (filter_tool);
+
+  g_object_set (filter_tool->config,
+                "channel", channel,
+                NULL);
+}
+
+static void
+gimp_levels_tool_config_notify (GimpFilterTool   *filter_tool,
+                                GimpConfig       *config,
+                                const GParamSpec *pspec)
+{
+  GimpLevelsTool   *levels_tool   = GIMP_LEVELS_TOOL (filter_tool);
+  GimpLevelsConfig *levels_config = GIMP_LEVELS_CONFIG (config);
+
+  GIMP_FILTER_TOOL_CLASS (parent_class)->config_notify (filter_tool,
+                                                        config, pspec);
+
+  if (! levels_tool->channel_menu ||
+      ! levels_tool->histogram_view)
+    return;
+
+  if (! strcmp (pspec->name, "linear"))
+    {
+      g_clear_object (&levels_tool->histogram);
+      g_clear_object (&levels_tool->histogram_async);
+      levels_tool->histogram = gimp_histogram_new (levels_config->linear);
+
+      levels_tool->histogram_async = gimp_drawable_calculate_histogram_async (
+        GIMP_TOOL (filter_tool)->drawable, levels_tool->histogram, FALSE);
+      gimp_histogram_view_set_histogram (GIMP_HISTOGRAM_VIEW (levels_tool->histogram_view),
+                                         levels_tool->histogram);
+    }
+  else if (! strcmp (pspec->name, "channel"))
+    {
+      gimp_histogram_view_set_channel (GIMP_HISTOGRAM_VIEW (levels_tool->histogram_view),
+                                       levels_config->channel);
+      gimp_color_bar_set_channel (GIMP_COLOR_BAR (levels_tool->output_bar),
+                                  levels_config->channel);
+      gimp_int_combo_box_set_active (GIMP_INT_COMBO_BOX (levels_tool->channel_menu),
+                                     levels_config->channel);
+    }
+  else if (! strcmp (pspec->name, "gamma")     ||
+           ! strcmp (pspec->name, "low-input") ||
+           ! strcmp (pspec->name, "high-input"))
+    {
+      gdouble low  = gtk_adjustment_get_value (levels_tool->low_input);
+      gdouble high = gtk_adjustment_get_value (levels_tool->high_input);
+      gdouble delta, mid, tmp, value;
+
+      gtk_adjustment_set_lower (levels_tool->high_input,   low);
+      gtk_adjustment_set_lower (levels_tool->gamma_linear, low);
+
+      gtk_adjustment_set_upper (levels_tool->low_input,    high);
+      gtk_adjustment_set_upper (levels_tool->gamma_linear, high);
+
+      levels_update_input_bar (levels_tool);
+
+      delta = (high - low) / 2.0;
+      mid   = low + delta;
+      tmp   = log10 (1.0 / levels_config->gamma[levels_config->channel]);
+      value = mid + delta * tmp;
+
+      gtk_adjustment_set_value (levels_tool->gamma_linear, value);
+    }
+}
+
+static gboolean
+gimp_levels_tool_settings_import (GimpFilterTool  *filter_tool,
+                                  GInputStream    *input,
+                                  GError         **error)
+{
+  GimpLevelsConfig *config = GIMP_LEVELS_CONFIG (filter_tool->config);
+  gchar             header[64];
+  gsize             bytes_read;
+
+  if (! g_input_stream_read_all (input, header, sizeof (header),
+                                 &bytes_read, NULL, error) ||
+      bytes_read != sizeof (header))
+    {
+      g_prefix_error (error, _("Could not read header: "));
+      return FALSE;
+    }
+
+  g_seekable_seek (G_SEEKABLE (input), 0, G_SEEK_SET, NULL, NULL);
+
+  if (g_str_has_prefix (header, "# GIMP Levels File\n"))
+    return gimp_levels_config_load_cruft (config, input, error);
+
+  return GIMP_FILTER_TOOL_CLASS (parent_class)->settings_import (filter_tool,
+                                                                 input,
+                                                                 error);
+}
+
+static gboolean
+gimp_levels_tool_settings_export (GimpFilterTool  *filter_tool,
+                                  GOutputStream   *output,
+                                  GError         **error)
+{
+  GimpLevelsTool   *tool   = GIMP_LEVELS_TOOL (filter_tool);
+  GimpLevelsConfig *config = GIMP_LEVELS_CONFIG (filter_tool->config);
+
+  if (tool->export_old_format)
+    return gimp_levels_config_save_cruft (config, output, error);
+
+  return GIMP_FILTER_TOOL_CLASS (parent_class)->settings_export (filter_tool,
+                                                                 output,
+                                                                 error);
+}
+
+static void
+levels_input_adjust_by_color (GimpLevelsConfig     *config,
+                              guint                 value,
+                              GimpHistogramChannel  channel,
+                              const GimpRGB        *color)
+{
+  switch (value & 0xF)
+    {
+    case PICK_LOW_INPUT:
+      gimp_levels_config_adjust_by_colors (config, channel, color, NULL, NULL);
+      break;
+    case PICK_GAMMA:
+      gimp_levels_config_adjust_by_colors (config, channel, NULL, color, NULL);
+      break;
+    case PICK_HIGH_INPUT:
+      gimp_levels_config_adjust_by_colors (config, channel, NULL, NULL, color);
+      break;
+    default:
+      break;
+    }
+}
+
+static void
+gimp_levels_tool_color_picked (GimpFilterTool *color_tool,
+                               gpointer        identifier,
+                               gdouble         x,
+                               gdouble         y,
+                               const Babl     *sample_format,
+                               const GimpRGB  *color)
+{
+  GimpFilterTool   *filter_tool = GIMP_FILTER_TOOL (color_tool);
+  GimpLevelsConfig *config      = GIMP_LEVELS_CONFIG (filter_tool->config);
+  GimpRGB           rgb         = *color;
+  guint             value       = GPOINTER_TO_UINT (identifier);
+
+  if (config->linear)
+    babl_process (babl_fish (babl_format ("R'G'B'A double"),
+                             babl_format ("RGBA double")),
+                  &rgb, &rgb, 1);
+
+  if (value & PICK_ALL_CHANNELS &&
+      gimp_babl_format_get_base_type (sample_format) == GIMP_RGB)
+    {
+      GimpHistogramChannel  channel;
+
+      /*  first reset the value channel  */
+      switch (value & 0xF)
+        {
+        case PICK_LOW_INPUT:
+          config->low_input[GIMP_HISTOGRAM_VALUE] = 0.0;
+          break;
+        case PICK_GAMMA:
+          config->gamma[GIMP_HISTOGRAM_VALUE] = 1.0;
+          break;
+        case PICK_HIGH_INPUT:
+          config->high_input[GIMP_HISTOGRAM_VALUE] = 1.0;
+          break;
+        default:
+          break;
+        }
+
+      /*  then adjust all color channels  */
+      for (channel = GIMP_HISTOGRAM_RED;
+           channel <= GIMP_HISTOGRAM_BLUE;
+           channel++)
+        {
+          levels_input_adjust_by_color (config, value, channel, &rgb);
+        }
+    }
+  else
+    {
+      levels_input_adjust_by_color (config, value, config->channel, &rgb);
+    }
+}
+
+static void
+gimp_levels_tool_export_setup (GimpSettingsBox      *settings_box,
+                               GtkFileChooserDialog *dialog,
+                               gboolean              export,
+                               GimpLevelsTool       *tool)
+{
+  GtkWidget *button;
+
+  if (! export)
+    return;
+
+  button = gtk_check_button_new_with_mnemonic (_("Use _old levels file format"));
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (button),
+                                tool->export_old_format);
+  gtk_file_chooser_set_extra_widget (GTK_FILE_CHOOSER (dialog), button);
+  gtk_widget_show (button);
+
+  g_signal_connect (button, "toggled",
+                    G_CALLBACK (gimp_toggle_button_update),
+                    &tool->export_old_format);
+}
+
+static void
+levels_update_input_bar (GimpLevelsTool *tool)
+{
+  GimpFilterTool   *filter_tool = GIMP_FILTER_TOOL (tool);
+  GimpLevelsConfig *config      = GIMP_LEVELS_CONFIG (filter_tool->config);
+
+  switch (config->channel)
+    {
+      gdouble value;
+
+    case GIMP_HISTOGRAM_VALUE:
+    case GIMP_HISTOGRAM_ALPHA:
+    case GIMP_HISTOGRAM_RGB:
+    case GIMP_HISTOGRAM_LUMINANCE:
+      {
+        guchar v[256];
+        gint   i;
+
+        for (i = 0; i < 256; i++)
+          {
+            value = gimp_operation_levels_map_input (config,
+                                                     config->channel,
+                                                     i / 255.0);
+            v[i] = CLAMP (value, 0.0, 1.0) * 255.999;
+          }
+
+        gimp_color_bar_set_buffers (GIMP_COLOR_BAR (tool->input_bar),
+                                    v, v, v);
+      }
+      break;
+
+    case GIMP_HISTOGRAM_RED:
+    case GIMP_HISTOGRAM_GREEN:
+    case GIMP_HISTOGRAM_BLUE:
+      {
+        guchar r[256];
+        guchar g[256];
+        guchar b[256];
+        gint   i;
+
+        for (i = 0; i < 256; i++)
+          {
+            value = gimp_operation_levels_map_input (config,
+                                                     GIMP_HISTOGRAM_RED,
+                                                     i / 255.0);
+            r[i] = CLAMP (value, 0.0, 1.0) * 255.999;
+
+            value = gimp_operation_levels_map_input (config,
+                                                     GIMP_HISTOGRAM_GREEN,
+                                                     i / 255.0);
+            g[i] = CLAMP (value, 0.0, 1.0) * 255.999;
+
+            value = gimp_operation_levels_map_input (config,
+                                                     GIMP_HISTOGRAM_BLUE,
+                                                     i / 255.0);
+            b[i] = CLAMP (value, 0.0, 1.0) * 255.999;
+          }
+
+        gimp_color_bar_set_buffers (GIMP_COLOR_BAR (tool->input_bar),
+                                    r, g, b);
+      }
+      break;
+    }
+}
+
+static void
+levels_channel_callback (GtkWidget      *widget,
+                         GimpFilterTool *filter_tool)
+{
+  GimpLevelsConfig *config = GIMP_LEVELS_CONFIG (filter_tool->config);
+  gint              value;
+
+  if (gimp_int_combo_box_get_active (GIMP_INT_COMBO_BOX (widget), &value) &&
+      config->channel != value)
+    {
+      g_object_set (config,
+                    "channel", value,
+                    NULL);
+    }
+}
+
+static void
+levels_channel_reset_callback (GtkWidget      *widget,
+                               GimpFilterTool *filter_tool)
+{
+  gimp_levels_config_reset_channel (GIMP_LEVELS_CONFIG (filter_tool->config));
+}
+
+static gboolean
+levels_menu_sensitivity (gint      value,
+                         gpointer  data)
+{
+  GimpDrawable         *drawable = GIMP_TOOL (data)->drawable;
+  GimpHistogramChannel  channel  = value;
+
+  if (!drawable)
+    return FALSE;
+
+  switch (channel)
+    {
+    case GIMP_HISTOGRAM_VALUE:
+      return TRUE;
+
+    case GIMP_HISTOGRAM_RED:
+    case GIMP_HISTOGRAM_GREEN:
+    case GIMP_HISTOGRAM_BLUE:
+      return gimp_drawable_is_rgb (drawable);
+
+    case GIMP_HISTOGRAM_ALPHA:
+      return gimp_drawable_has_alpha (drawable);
+
+    case GIMP_HISTOGRAM_RGB:
+      return FALSE;
+
+    case GIMP_HISTOGRAM_LUMINANCE:
+      return FALSE;
+    }
+
+  return FALSE;
+}
+
+static void
+levels_stretch_callback (GtkWidget      *widget,
+                         GimpLevelsTool *levels_tool)
+{
+  GimpTool       *tool        = GIMP_TOOL (levels_tool);
+  GimpFilterTool *filter_tool = GIMP_FILTER_TOOL (levels_tool);
+  GimpWaitable   *waitable;
+
+  waitable = gimp_trivially_cancelable_waitable_new (
+    GIMP_WAITABLE (levels_tool->histogram_async));
+
+  gimp_wait (tool->tool_info->gimp, waitable, _("Calculating histogram..."));
+
+  g_object_unref (waitable);
+
+  if (gimp_async_is_synced   (levels_tool->histogram_async) &&
+      gimp_async_is_finished (levels_tool->histogram_async))
+    {
+      gimp_levels_config_stretch (GIMP_LEVELS_CONFIG (filter_tool->config),
+                                  levels_tool->histogram,
+                                  gimp_drawable_is_rgb (tool->drawable));
+    }
+}
+
+static void
+levels_linear_gamma_changed (GtkAdjustment  *adjustment,
+                             GimpLevelsTool *tool)
+{
+  gdouble low_input  = gtk_adjustment_get_value (tool->low_input);
+  gdouble high_input = gtk_adjustment_get_value (tool->high_input);
+  gdouble delta, mid, tmp, value;
+
+  delta = (high_input - low_input) / 2.0;
+
+  if (delta >= 0.5)
+    {
+      mid   = low_input + delta;
+      tmp   = (gtk_adjustment_get_value (adjustment) - mid) / delta;
+      value = 1.0 / pow (10, tmp);
+
+      /*  round the gamma value to the nearest 1/100th  */
+      value = floor (value * 100 + 0.5) / 100.0;
+
+      gtk_adjustment_set_value (tool->gamma, value);
+    }
+}
+
+static void
+levels_to_curves_callback (GtkWidget      *widget,
+                           GimpFilterTool *filter_tool)
+{
+  GimpLevelsConfig *config = GIMP_LEVELS_CONFIG (filter_tool->config);
+  GimpCurvesConfig *curves;
+
+  curves = gimp_levels_config_to_curves_config (config);
+
+  gimp_filter_tool_edit_as (filter_tool,
+                            "gimp-curves-tool",
+                            GIMP_CONFIG (curves));
+
+  g_object_unref (curves);
+}