GPencil: Refactor Append operators

Now the operators work like other areas of Blender using the list of selected objects.

Also, the name has been changed to:

```Layers:
- Copy Layer to Selected
- Copy All Layers to Selected

Materials:
- Copy Material to Selected
- Copy All Materials to Selected```

Reviewed By: mendio, pablovazquez, pepeland

Differential Revision: https://developer.blender.org/D11216

3 files changed, 18 insertions, 10 deletions

diff --git a/source/blender/blenkernel/intern/gpencil.c b/source/blender/blenkernel/intern/gpencil.c
index 9c84d155330..421cb0ac4f1 100644
--- a/source/blender/blenkernel/intern/gpencil.c
+++ b/source/blender/blenkernel/intern/gpencil.c
@@ -653,9 +653,13 @@ bGPDframe *BKE_gpencil_frame_addcopy(bGPDlayer *gpl, int cframe)
  * \param gpd: Grease pencil data-block
  * \param name: Name of the layer
  * \param setactive: Set as active
+ * \param add_to_header: Used to force the layer added at header
  * \return Pointer to new layer
  */
-bGPDlayer *BKE_gpencil_layer_addnew(bGPdata *gpd, const char *name, bool setactive)
+bGPDlayer *BKE_gpencil_layer_addnew(bGPdata *gpd,
+                                    const char *name,
+                                    const bool setactive,
+                                    const bool add_to_header)
 {
   bGPDlayer *gpl = NULL;
   bGPDlayer *gpl_active = NULL;
@@ -671,14 +675,18 @@ bGPDlayer *BKE_gpencil_layer_addnew(bGPdata *gpd, const char *name, bool setacti
   gpl_active = BKE_gpencil_layer_active_get(gpd);
 
   /* Add to data-block. */
-  if (gpl_active == NULL) {
-    BLI_addtail(&gpd->layers, gpl);
+  if (add_to_header) {
+    BLI_addhead(&gpd->layers, gpl);
   }
   else {
-    /* if active layer, add after that layer */
-    BLI_insertlinkafter(&gpd->layers, gpl_active, gpl);
+    if (gpl_active == NULL) {
+      BLI_addtail(&gpd->layers, gpl);
+    }
+    else {
+      /* if active layer, add after that layer */
+      BLI_insertlinkafter(&gpd->layers, gpl_active, gpl);
+    }
   }
-
   /* annotation vs GP Object behavior is slightly different */
   if (gpd->flag & GP_DATA_ANNOTATIONS) {
     /* set default color of new strokes for this layer */
diff --git a/source/blender/blenkernel/intern/gpencil_curve.c b/source/blender/blenkernel/intern/gpencil_curve.c
index 88d3e917a7a..906d0fb0792 100644
--- a/source/blender/blenkernel/intern/gpencil_curve.c
+++ b/source/blender/blenkernel/intern/gpencil_curve.c
@@ -515,7 +515,7 @@ void BKE_gpencil_convert_curve(Main *bmain,
     if (collection != NULL) {
       gpl = BKE_gpencil_layer_named_get(gpd, collection->id.name + 2);
       if (gpl == NULL) {
-        gpl = BKE_gpencil_layer_addnew(gpd, collection->id.name + 2, true);
+        gpl = BKE_gpencil_layer_addnew(gpd, collection->id.name + 2, true, false);
       }
     }
   }
@@ -523,7 +523,7 @@ void BKE_gpencil_convert_curve(Main *bmain,
   if (gpl == NULL) {
     gpl = BKE_gpencil_layer_active_get(gpd);
     if (gpl == NULL) {
-      gpl = BKE_gpencil_layer_addnew(gpd, DATA_("GP_Layer"), true);
+      gpl = BKE_gpencil_layer_addnew(gpd, DATA_("GP_Layer"), true, false);
     }
   }
 
diff --git a/source/blender/blenkernel/intern/gpencil_geom.c b/source/blender/blenkernel/intern/gpencil_geom.c
index 04403e264a4..501ee0c2014 100644
--- a/source/blender/blenkernel/intern/gpencil_geom.c
+++ b/source/blender/blenkernel/intern/gpencil_geom.c
@@ -2439,7 +2439,7 @@ bool BKE_gpencil_convert_mesh(Main *bmain,
       /* Create Layer and Frame. */
       bGPDlayer *gpl_fill = BKE_gpencil_layer_named_get(gpd, element_name);
       if (gpl_fill == NULL) {
-        gpl_fill = BKE_gpencil_layer_addnew(gpd, element_name, true);
+        gpl_fill = BKE_gpencil_layer_addnew(gpd, element_name, true, false);
       }
       bGPDframe *gpf_fill = BKE_gpencil_layer_frame_get(
           gpl_fill, CFRA + frame_offset, GP_GETFRAME_ADD_NEW);
@@ -2492,7 +2492,7 @@ bool BKE_gpencil_convert_mesh(Main *bmain,
   /* Create Layer and Frame. */
   bGPDlayer *gpl_stroke = BKE_gpencil_layer_named_get(gpd, element_name);
   if (gpl_stroke == NULL) {
-    gpl_stroke = BKE_gpencil_layer_addnew(gpd, element_name, true);
+    gpl_stroke = BKE_gpencil_layer_addnew(gpd, element_name, true, false);
   }
   bGPDframe *gpf_stroke = BKE_gpencil_layer_frame_get(
       gpl_stroke, CFRA + frame_offset, GP_GETFRAME_ADD_NEW);