Fix T42859 smart UV unwrap does not support aspect correction.

Can be considered TODO but it's not bad to support either. Also added
RNA api to get aspect ratio of assigned UV image - returns aspect
corrected image dimensions so needs adjustments for uv editing.

release/scripts/startup/bl_operators/uvcalc_smart_project.py

@@ -708,6 +708,7 @@ def main(context,
          island_margin,
          projection_limit,
          user_area_weight,
+         use_aspect
          ):
     global USER_FILL_HOLES
     global USER_FILL_HOLES_QUALITY
@@ -720,7 +721,6 @@ def main(context,
     global dict_matrix
     dict_matrix = {}
 
-
     # Constants:
     # Takes a list of faces that make up a UV island and rotate
     # until they optimally fit inside a square.
@@ -992,9 +992,31 @@ def main(context,
     print("Smart Projection time: %.2f" % (time.time() - time1))
     # Window.DrawProgressBar(0.9, "Smart Projections done, time: %.2f sec" % (time.time() - time1))
 
+    # aspect correction is only done in edit mode - and only smart unwrap supports currently
     if is_editmode:
         bpy.ops.object.mode_set(mode='EDIT')
 
+        if use_aspect:
+           import bmesh
+           aspect = context.scene.uvedit_aspect(context.active_object)
+           if aspect[0] > aspect[1]:
+               aspect[0] = aspect[1]/aspect[0];
+               aspect[1] = 1.0
+           else:
+               aspect[1] = aspect[0]/aspect[1];
+               aspect[0] = 1.0
+
+           bm = bmesh.from_edit_mesh(me)
+
+           uv_act = bm.loops.layers.uv.active
+
+           faces = [f for f in bm.faces if f.select]
+
+           for f in faces:
+               for l in f.loops:
+                   l[uv_act].uv[0] *= aspect[0]
+                   l[uv_act].uv[1] *= aspect[1]
+
     dict_matrix.clear()
 
 #XXX	Window.DrawProgressBar(1.0, "")
@@ -1017,7 +1039,7 @@ def main(context,
     ]
 """
 
-from bpy.props import FloatProperty
+from bpy.props import FloatProperty, BoolProperty
 
 
 class SmartProject(Operator):
@@ -1046,6 +1068,11 @@ class SmartProject(Operator):
             min=0.0, max=1.0,
             default=0.0,
             )
+    use_aspect = BoolProperty(
+            name="Correct Aspect",
+            description="Map UVs taking image aspect ratio into account",
+            default=True
+            )
 
     @classmethod
     def poll(cls, context):
@@ -1056,6 +1083,7 @@ class SmartProject(Operator):
              self.island_margin,
              self.angle_limit,
              self.user_area_weight,
+             self.use_aspect
              )
         return {'FINISHED'}
 

source/blender/editors/include/ED_uvedit.h

@@ -94,6 +94,8 @@ void uvedit_uv_select_disable(struct BMEditMesh *em, struct Scene *scene, struct
 bool ED_uvedit_nearest_uv(struct Scene *scene, struct Object *obedit, struct Image *ima,
                           const float co[2], float r_uv[2]);
 
+void ED_uvedit_get_aspect(struct Scene *scene, struct Object *ob, struct BMesh *em, float *aspx, float *aspy);
+
 /* uvedit_unwrap_ops.c */
 void ED_uvedit_live_unwrap_begin(struct Scene *scene, struct Object *obedit);
 void ED_uvedit_live_unwrap_re_solve(void);

source/blender/editors/uvedit/uvedit_intern.h

@@ -72,7 +72,6 @@ void uv_find_nearest_edge(struct Scene *scene, struct Image *ima, struct BMEditM
 /* utility tool functions */
 
 void uvedit_live_unwrap_update(struct SpaceImage *sima, struct Scene *scene, struct Object *obedit);
-void uvedit_get_aspect(struct Scene *scene, struct Object *ob, struct BMesh *em, float *aspx, float *aspy);
 
 /* operators */
 

source/blender/editors/uvedit/uvedit_smart_stitch.c

@@ -1660,7 +1660,7 @@ static int stitch_init(bContext *C, wmOperator *op)
 		return 0;
 	}
 
-	uvedit_get_aspect(scene, obedit, em->bm, &aspx, &aspy);
+	ED_uvedit_get_aspect(scene, obedit, em->bm, &aspx, &aspy);
 	state->aspect = aspx / aspy;
 
 	/* Entirely possible if redoing last operator that static island is bigger than total number of islands.

source/blender/editors/uvedit/uvedit_unwrap_ops.c

@@ -190,7 +190,7 @@ static bool uvedit_have_selection(Scene *scene, BMEditMesh *em, bool implicit)
 	return false;
 }
 
-void uvedit_get_aspect(Scene *scene, Object *ob, BMesh *bm, float *aspx, float *aspy)
+void ED_uvedit_get_aspect(Scene *scene, Object *ob, BMesh *bm, float *aspx, float *aspy)
 {
 	bool sloppy = true;
 	bool selected = false;
@@ -264,7 +264,7 @@ static ParamHandle *construct_param_handle(Scene *scene, Object *ob, BMesh *bm,
 	if (correct_aspect) {
 		float aspx, aspy;
 
-		uvedit_get_aspect(scene, ob, bm, &aspx, &aspy);
+		ED_uvedit_get_aspect(scene, ob, bm, &aspx, &aspy);
 
 		if (aspx != aspy)
 			param_aspect_ratio(handle, aspx, aspy);
@@ -376,7 +376,7 @@ static ParamHandle *construct_param_handle_subsurfed(Scene *scene, Object *ob, B
 	if (correct_aspect) {
 		float aspx, aspy;
 
-		uvedit_get_aspect(scene, ob, em->bm, &aspx, &aspy);
+		ED_uvedit_get_aspect(scene, ob, em->bm, &aspx, &aspy);
 
 		if (aspx != aspy)
 			param_aspect_ratio(handle, aspx, aspy);
@@ -1010,7 +1010,7 @@ static void correct_uv_aspect(Scene *scene, Object *ob, BMEditMesh *em)
 	
 	const int cd_loop_uv_offset = CustomData_get_offset(&em->bm->ldata, CD_MLOOPUV);
 
-	uvedit_get_aspect(scene, ob, em->bm, &aspx, &aspy);
+	ED_uvedit_get_aspect(scene, ob, em->bm, &aspx, &aspy);
 	
 	if (aspx == aspy)
 		return;

source/blender/makesrna/intern/rna_scene_api.c

@@ -47,12 +47,14 @@
 
 #include "BKE_animsys.h"
 #include "BKE_depsgraph.h"
+#include "BKE_editmesh.h"
 #include "BKE_global.h"
 #include "BKE_image.h"
 #include "BKE_scene.h"
 #include "BKE_writeavi.h"
 
 #include "ED_transform.h"
+#include "ED_uvedit.h"
 
 #ifdef WITH_PYTHON
 #  include "BPY_extern.h"
@@ -90,6 +92,23 @@ static void rna_Scene_frame_set(Scene *scene, int frame, float subframe)
 	}
 }
 
+static void rna_Scene_uvedit_aspect(Scene *scene, Object *ob, float *aspect)
+{
+	BMEditMesh *em;
+	if (!(ob && ob->type == OB_MESH && ob->mode == OB_MODE_EDIT)) {
+		aspect[0] = aspect[1]= 1.0f;
+		return;
+	}
+	
+	em = BKE_editmesh_from_object(ob);
+	if (!EDBM_mtexpoly_check(em)) {
+		aspect[0] = aspect[1]= 1.0f;
+		return;
+	}
+	
+	ED_uvedit_get_aspect(scene, ob, em->bm, aspect, aspect + 1);
+}
+
 static void rna_Scene_update_tagged(Scene *scene)
 {
 #ifdef WITH_PYTHON
@@ -191,6 +210,15 @@ void RNA_api_scene(StructRNA *srna)
 	RNA_def_function_ui_description(func,
 	                                "Update data tagged to be updated from previous access to data or operators");
 
+	func = RNA_def_function(srna, "uvedit_aspect", "rna_Scene_uvedit_aspect");
+	RNA_def_function_ui_description(func, "Get uv aspect for current object");
+	parm = RNA_def_pointer(func, "object", "Object", "", "Object");
+	RNA_def_property_flag(parm, PROP_REQUIRED);
+
+	parm = RNA_def_float_vector(func, "aspect", 2, NULL, 0.0f, FLT_MAX, "", "aspect", 0.0f, FLT_MAX);
+	RNA_def_property_flag(parm, PROP_THICK_WRAP);
+	RNA_def_function_output(func, parm);
+	
 	/* Ray Cast */
 	func = RNA_def_function(srna, "ray_cast", "rna_Scene_ray_cast");
 	RNA_def_function_ui_description(func, "Cast a ray onto in object space");