[gimp/gimp-2-10] app: expand functionality of merge-down button

[Michael Natterer <mitch src gnome org>]

commit b419aa5d10f7fc592de013bc0620522f277e45a4
Author: woob <thetoastcaper gmail com>
Date:   Thu Dec 19 22:58:31 2019 -0500

    app: expand functionality of merge-down button
    
    Adds a number of modifier keys to the layer dockable's new "Merge Down"
    button to access further functions, and adds among them a new action to
    merge visible layers using the dialog's last values, akin to those
    accompanying the New Layer and Add Layer Mask dialogs.
    
    Modifier keys are bound as follows:
      Shift -> Merge layer group
      Ctrl -> Merge visible layers
      Ctrl + Shift -> Merge visible layers from last used values
    
    The Merge Down button is kept sensitive even when the current layer
    can't be merged down to allow access to these functions
    
    (cherry picked from commit a11ada4ce2fa47d7e0a5e617abaff48d5cea06f3)

 app/actions/image-commands.c    | 22 ++++++++++++++++++++++
 app/actions/image-commands.h    |  3 +++
 app/actions/layers-actions.c    | 31 ++++++++++++++++++++++++-------
 app/widgets/gimplayertreeview.c | 10 +++++++++-
 4 files changed, 58 insertions(+), 8 deletions(-)
---
diff --git a/app/actions/image-commands.c b/app/actions/image-commands.c
index 07b2f7ef76..6dae5f540c 100644
--- a/app/actions/image-commands.c
+++ b/app/actions/image-commands.c
@@ -954,6 +954,28 @@ image_merge_layers_cmd_callback (GimpAction *action,
   gtk_window_present (GTK_WINDOW (dialog));
 }
 
+void
+image_merge_layers_last_vals_cmd_callback (GimpAction *action,
+                                           GVariant   *value,
+                                           gpointer    data)
+{
+  GimpImage        *image;
+  GimpDisplay      *display;
+  GimpDialogConfig *config;
+  return_if_no_image (image, data);
+  return_if_no_display (display, data);
+
+  config = GIMP_DIALOG_CONFIG (image->gimp->config);
+
+  image_merge_layers_callback (NULL,
+                               image,
+                               action_data_get_context (data),
+                               config->layer_merge_type,
+                               config->layer_merge_active_group_only,
+                               config->layer_merge_discard_invisible,
+                               display);
+}
+
 void
 image_flatten_image_cmd_callback (GimpAction *action,
                                   GVariant   *value,
diff --git a/app/actions/image-commands.h b/app/actions/image-commands.h
index d2e3e1f345..018dec7e7b 100644
--- a/app/actions/image-commands.h
+++ b/app/actions/image-commands.h
@@ -83,6 +83,9 @@ void   image_crop_to_content_cmd_callback          (GimpAction *action,
 void   image_merge_layers_cmd_callback             (GimpAction *action,
                                                     GVariant   *value,
                                                     gpointer    data);
+void   image_merge_layers_last_vals_cmd_callback   (GimpAction *action,
+                                                    GVariant   *value,
+                                                    gpointer    data);
 void   image_flatten_image_cmd_callback            (GimpAction *action,
                                                     GVariant   *value,
                                                     gpointer    data);
diff --git a/app/actions/layers-actions.c b/app/actions/layers-actions.c
index 86a3c7c18b..2100696b17 100644
--- a/app/actions/layers-actions.c
+++ b/app/actions/layers-actions.c
@@ -177,6 +177,15 @@ static const GimpActionEntry layers_actions[] =
     layers_merge_down_cmd_callback,
     GIMP_HELP_LAYER_MERGE_DOWN },
 
+  /* this is the same as layers-merge-down, except it's sensitive even if
+   * the layer can't be merged down
+   */
+  { "layers-merge-down-button", GIMP_ICON_LAYER_MERGE_DOWN,
+    NC_("layers-action", "Merge Do_wn"), NULL,
+    NC_("layers-action", "Merge this layer with the first visible layer below it"),
+    layers_merge_down_cmd_callback,
+    GIMP_HELP_LAYER_MERGE_DOWN },
+
   { "layers-merge-group", NULL,
     NC_("layers-action", "Merge Layer Group"), NULL,
     NC_("layers-action", "Merge the layer group's layers into one normal layer"),
@@ -189,6 +198,12 @@ static const GimpActionEntry layers_actions[] =
     image_merge_layers_cmd_callback,
     GIMP_HELP_IMAGE_MERGE_LAYERS },
 
+  { "layers-merge-layers-last-values", NULL,
+    NC_("layers-action", "Merge _Visible Layers"), NULL,
+    NC_("layers-action", "Merge all visible layers with last used values"),
+    image_merge_layers_last_vals_cmd_callback,
+    GIMP_HELP_IMAGE_MERGE_LAYERS },
+
   { "layers-flatten-image", NULL,
     NC_("layers-action", "_Flatten Image"), NULL,
     NC_("layers-action", "Merge all layers into one and remove transparency"),
@@ -937,13 +952,15 @@ layers_actions_update (GimpActionGroup *group,
   SET_SENSITIVE ("layers-lower",            layer && !fs && !ac && next);
   SET_SENSITIVE ("layers-lower-to-bottom",  layer && !fs && !ac && next);
 
-  SET_VISIBLE   ("layers-anchor",           layer &&  fs && !ac);
-  SET_VISIBLE   ("layers-merge-down",       !fs);
-  SET_SENSITIVE ("layers-merge-down",       layer && !fs && !ac && visible && next_visible);
-  SET_VISIBLE   ("layers-merge-group",      children);
-  SET_SENSITIVE ("layers-merge-group",      layer && !fs && !ac && children);
-  SET_SENSITIVE ("layers-merge-layers",     layer && !fs && !ac);
-  SET_SENSITIVE ("layers-flatten-image",    layer && !fs && !ac);
+  SET_VISIBLE   ("layers-anchor",            layer &&  fs && !ac);
+  SET_VISIBLE   ("layers-merge-down",        !fs);
+  SET_SENSITIVE ("layers-merge-down",        layer && !fs && !ac && visible && next_visible);
+  SET_VISIBLE   ("layers-merge-down-button", !fs);
+  SET_SENSITIVE ("layers-merge-down-button", layer && !fs && !ac);
+  SET_VISIBLE   ("layers-merge-group",       children);
+  SET_SENSITIVE ("layers-merge-group",       layer && !fs && !ac && children);
+  SET_SENSITIVE ("layers-merge-layers",      layer && !fs && !ac);
+  SET_SENSITIVE ("layers-flatten-image",     layer && !fs && !ac);
 
   SET_VISIBLE   ("layers-text-discard",       text_layer && !ac);
   SET_VISIBLE   ("layers-text-to-vectors",    text_layer && !ac);
diff --git a/app/widgets/gimplayertreeview.c b/app/widgets/gimplayertreeview.c
index 35cdc7cb92..9b615040dc 100644
--- a/app/widgets/gimplayertreeview.c
+++ b/app/widgets/gimplayertreeview.c
@@ -401,7 +401,15 @@ gimp_layer_tree_view_constructed (GObject *object)
                          button, 5);
 
   button = gimp_editor_add_action_button (GIMP_EDITOR (layer_view), "layers",
-                                          "layers-merge-down", NULL);
+                                          "layers-merge-down-button",
+                                          "layers-merge-group",
+                                          GDK_SHIFT_MASK,
+                                          "layers-merge-layers",
+                                          GDK_CONTROL_MASK,
+                                          "layers-merge-layers-last-values",
+                                          GDK_CONTROL_MASK |
+                                          GDK_SHIFT_MASK,
+                                          NULL);
   gimp_container_view_enable_dnd (GIMP_CONTAINER_VIEW (layer_view),
                                   GTK_BUTTON (button),
                                   GIMP_TYPE_LAYER);