/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * 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 2
 * 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, write to the Free Software  Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) Blender Foundation, 2002-2009
 * All rights reserved.
 *
 * Contributor(s): Antony Riakiotakis
 *
 * ***** END GPL LICENSE BLOCK *****
 *
 * UV Sculpt tools
 *
 */

/** \file blender/editors/sculpt_paint/sculpt_uv.c
 *  \ingroup edsculpt
 */


#include "MEM_guardedalloc.h"

#include "BLI_utildefines.h"
#include "BLI_math.h"
#include "BLI_ghash.h"

#include "DNA_object_types.h"
#include "DNA_scene_types.h"
#include "DNA_brush_types.h"
#include "DNA_meshdata_types.h"

#include "BKE_brush.h"
#include "BKE_paint.h"
#include "BKE_colortools.h"
#include "BKE_context.h"
#include "BKE_depsgraph.h"
#include "BKE_mesh_mapping.h"
#include "BKE_customdata.h"
#include "BKE_editmesh.h"

#include "ED_screen.h"
#include "ED_image.h"
#include "ED_mesh.h"

#include "WM_api.h"
#include "WM_types.h"

#include "RNA_access.h"
#include "RNA_define.h"
#include "RNA_enum_types.h"

#include "paint_intern.h"
#include "uvedit_intern.h"

#include "BIF_gl.h"
#include "BIF_glutil.h"

#include "UI_view2d.h"

#define MARK_BOUNDARY   1

typedef struct UvAdjacencyElement {
	/* pointer to original uvelement */
	UvElement *element;
	/* uv pointer for convenience. Caution, this points to the original UVs! */
	float *uv;
	/* general use flag (Used to check if Element is boundary here) */
	char flag;
} UvAdjacencyElement;

typedef struct UvEdge {
	unsigned int uv1;
	unsigned int uv2;
	/* general use flag (Used to check if edge is boundary here, and propagates to adjacency elements) */
	char flag;
} UvEdge;

typedef struct UVInitialStrokeElement {
	/* index to unique uv */
	int uv;

	/* strength of brush on initial position */
	float strength;

	/* initial uv position */
	float initial_uv[2];
} UVInitialStrokeElement;

typedef struct UVInitialStroke {
	/* Initial Selection,for grab brushes for instance */
	UVInitialStrokeElement *initialSelection;

	/* total initially selected UVs*/
	int totalInitialSelected;

	/* initial mouse coordinates */
	float init_coord[2];
} UVInitialStroke;


/* custom data for uv smoothing brush */
typedef struct UvSculptData {
	/* Contains the first of each set of coincident uvs.
	 * These will be used to perform smoothing on and propagate the changes
	 * to their coincident uvs */
	UvAdjacencyElement *uv;

	/* ...Is what it says */
	int totalUniqueUvs;

	/* Edges used for adjacency info, used with laplacian smoothing */
	UvEdge *uvedges;

	/* need I say more? */
	int totalUvEdges;

	/* data for initial stroke, used by tools like grab */
	UVInitialStroke *initial_stroke;

	/* timer to be used for airbrush-type brush */
	wmTimer *timer;

	/* to determine quickly adjacent uvs */
	UvElementMap *elementMap;

	/* uvsmooth Paint for fast reference */
	Paint *uvsculpt;
	
	/* tool to use. duplicating here to change if modifier keys are pressed */
	char tool;

	/* store invert flag here */
	char invert;
} UvSculptData;


static Brush *uv_sculpt_brush(bContext *C)
{
	Scene *scene = CTX_data_scene(C);
	ToolSettings *settings = scene->toolsettings;

	if (!settings->uvsculpt)
		return NULL;
	return BKE_paint_brush(&settings->uvsculpt->paint);
}


static int uv_sculpt_brush_poll(bContext *C)
{
	BMEditMesh *em;
	int ret;
	Object *obedit = CTX_data_edit_object(C);
	SpaceImage *sima = CTX_wm_space_image(C);
	Scene *scene = CTX_data_scene(C);
	ToolSettings *toolsettings = scene->toolsettings;

	if (!uv_sculpt_brush(C) || !obedit || obedit->type != OB_MESH ||
	    !sima || ED_space_image_show_render(sima) || (sima->mode == SI_MODE_PAINT))
	{
		return 0;
	}

	em = BKE_editmesh_from_object(obedit);
	ret = EDBM_mtexpoly_check(em);

	if (ret) {
		ARegion *ar = CTX_wm_region(C);
		if ((toolsettings->use_uv_sculpt) && ar->regiontype == RGN_TYPE_WINDOW)
			return 1;
	}

	return 0;
}

static void brush_drawcursor_uvsculpt(bContext *C, int x, int y, void *UNUSED(customdata))
{
#define PX_SIZE_FADE_MAX 12.0f
#define PX_SIZE_FADE_MIN 4.0f

	Scene *scene = CTX_data_scene(C);
	//Brush *brush = image_paint_brush(C);
	Paint *paint = BKE_paint_get_active_from_context(C);
	Brush *brush = BKE_paint_brush(paint);

	if (paint && brush && paint->flags & PAINT_SHOW_BRUSH) {
		const float size = (float)BKE_brush_size_get(scene, brush);
		float alpha = 0.5f;

		/* fade out the brush (cheap trick to work around brush interfering with sampling [#])*/
		if (size < PX_SIZE_FADE_MIN) {
			return;
		}
		else if (size < PX_SIZE_FADE_MAX) {
			alpha *= (size - PX_SIZE_FADE_MIN) / (PX_SIZE_FADE_MAX - PX_SIZE_FADE_MIN);
		}

		glPushMatrix();

		glTranslatef((float)x, (float)y, 0.0f);

		glColor4f(brush->add_col[0], brush->add_col[1], brush->add_col[2], alpha);
		glEnable(GL_LINE_SMOOTH);
		glEnable(GL_BLEND);
		glutil_draw_lined_arc(0, (float)(M_PI * 2.0), size, 40);
		glDisable(GL_BLEND);
		glDisable(GL_LINE_SMOOTH);

		glPopMatrix();
	}
#undef PX_SIZE_FADE_MAX
#undef PX_SIZE_FADE_MIN
}


void ED_space_image_uv_sculpt_update(wmWindowManager *wm, ToolSettings *settings)
{
	if (settings->use_uv_sculpt) {
		if (!settings->uvsculpt) {
			settings->uvsculpt = MEM_callocN(sizeof(*settings->uvsculpt), "UV Smooth paint");
			settings->uv_sculpt_tool = UV_SCULPT_TOOL_GRAB;
			settings->uv_sculpt_settings = UV_SCULPT_LOCK_BORDERS | UV_SCULPT_ALL_ISLANDS;
			settings->uv_relax_method = UV_SCULPT_TOOL_RELAX_LAPLACIAN;
			/* Uv sculpting does not include explicit brush view control yet, always enable */
			settings->uvsculpt->paint.flags |= PAINT_SHOW_BRUSH;
		}

		BKE_paint_init(&settings->uvsculpt->paint, PAINT_CURSOR_SCULPT);

		settings->uvsculpt->paint.paint_cursor = WM_paint_cursor_activate(wm, uv_sculpt_brush_poll,
		                                                                  brush_drawcursor_uvsculpt, NULL);
	}
	else {
		if (settings->uvsculpt) {
			WM_paint_cursor_end(wm, settings->uvsculpt->paint.paint_cursor);
			settings->uvsculpt->paint.paint_cursor = NULL;
		}
	}
}

int uv_sculpt_poll(bContext *C)
{
	return uv_sculpt_brush_poll(C);
}

/*********** Improved Laplacian Relaxation Operator ************************/
/* original code by Raul Fernandez Hernandez "farsthary"                   *
 * adapted to uv smoothing by Antony Riakiatakis                           *
 ***************************************************************************/

typedef struct Temp_UvData {
	float sum_co[2], p[2], b[2], sum_b[2];
	int ncounter;
} Temp_UVData;



static void HC_relaxation_iteration_uv(BMEditMesh *em, UvSculptData *sculptdata, float mouse_coord[2],
                                       float alpha, float radius, float aspectRatio)
{
	Temp_UVData *tmp_uvdata;
	float diff[2];
	int i;
	float radius_root = sqrt(radius);
	Brush *brush = BKE_paint_brush(sculptdata->uvsculpt);

	tmp_uvdata = (Temp_UVData *)MEM_callocN(sculptdata->totalUniqueUvs * sizeof(Temp_UVData), "Temporal data");

	/* counting neighbors */
	for (i = 0; i < sculptdata->totalUvEdges; i++) {
		UvEdge *tmpedge = sculptdata->uvedges + i;
		tmp_uvdata[tmpedge->uv1].ncounter++;
		tmp_uvdata[tmpedge->uv2].ncounter++;

		add_v2_v2(tmp_uvdata[tmpedge->uv2].sum_co, sculptdata->uv[tmpedge->uv1].uv);
		add_v2_v2(tmp_uvdata[tmpedge->uv1].sum_co, sculptdata->uv[tmpedge->uv2].uv);
	}

	for (i = 0; i < sculptdata->totalUniqueUvs; i++) {
		copy_v2_v2(diff, tmp_uvdata[i].sum_co);
		mul_v2_fl(diff, 1.f / tmp_uvdata[i].ncounter);
		copy_v2_v2(tmp_uvdata[i].p, diff);

		tmp_uvdata[i].b[0] = diff[0] - sculptdata->uv[i].uv[0];
		tmp_uvdata[i].b[1] = diff[1] - sculptdata->uv[i].uv[1];
	}

	for (i = 0; i < sculptdata->totalUvEdges; i++) {
		UvEdge *tmpedge = sculptdata->uvedges + i;
		add_v2_v2(tmp_uvdata[tmpedge->uv1].sum_b, tmp_uvdata[tmpedge->uv2].b);
		add_v2_v2(tmp_uvdata[tmpedge->uv2].sum_b, tmp_uvdata[tmpedge->uv1].b);
	}

	for (i = 0; i < sculptdata->totalUniqueUvs; i++) {
		float dist;
		/* This is supposed to happen only if "Pin Edges" is on, since we have initialization on stroke start
		 * If ever uv brushes get their own mode we should check for toolsettings option too */
		if ((sculptdata->uv[i].flag & MARK_BOUNDARY)) {
			continue;
		}

		sub_v2_v2v2(diff, sculptdata->uv[i].uv, mouse_coord);
		diff[1] /= aspectRatio;
		if ((dist = dot_v2v2(diff, diff)) <= radius) {
			UvElement *element;
			float strength;
			strength = alpha * BKE_brush_curve_strength(brush, sqrt(dist), radius_root);

			sculptdata->uv[i].uv[0] = (1.0f - strength) * sculptdata->uv[i].uv[0] + strength * (tmp_uvdata[i].p[0] - 0.5f * (tmp_uvdata[i].b[0] + tmp_uvdata[i].sum_b[0] / tmp_uvdata[i].ncounter));
			sculptdata->uv[i].uv[1] = (1.0f - strength) * sculptdata->uv[i].uv[1] + strength * (tmp_uvdata[i].p[1] - 0.5f * (tmp_uvdata[i].b[1] + tmp_uvdata[i].sum_b[1] / tmp_uvdata[i].ncounter));

			for (element = sculptdata->uv[i].element; element; element = element->next) {
				MLoopUV *luv;
				BMLoop *l;

				if (element->separate && element != sculptdata->uv[i].element)
					break;

				l = element->l;
				luv = CustomData_bmesh_get(&em->bm->ldata, l->head.data, CD_MLOOPUV);
				copy_v2_v2(luv->uv, sculptdata->uv[i].uv);
			}
		}
	}

	MEM_freeN(tmp_uvdata);

	return;
}

static void laplacian_relaxation_iteration_uv(BMEditMesh *em, UvSculptData *sculptdata, float mouse_coord[2], float alpha, float radius, float aspectRatio)
{
	Temp_UVData *tmp_uvdata;
	float diff[2];
	int i;
	float radius_root = sqrt(radius);
	Brush *brush = BKE_paint_brush(sculptdata->uvsculpt);

	tmp_uvdata = (Temp_UVData *)MEM_callocN(sculptdata->totalUniqueUvs * sizeof(Temp_UVData), "Temporal data");

	/* counting neighbors */
	for (i = 0; i < sculptdata->totalUvEdges; i++) {
		UvEdge *tmpedge = sculptdata->uvedges + i;
		tmp_uvdata[tmpedge->uv1].ncounter++;
		tmp_uvdata[tmpedge->uv2].ncounter++;

		add_v2_v2(tmp_uvdata[tmpedge->uv2].sum_co, sculptdata->uv[tmpedge->uv1].uv);
		add_v2_v2(tmp_uvdata[tmpedge->uv1].sum_co, sculptdata->uv[tmpedge->uv2].uv);
	}

	/* Original Lacplacian algorithm included removal of normal component of translation. here it is not
	 * needed since we translate along the UV plane always.*/
	for (i = 0; i < sculptdata->totalUniqueUvs; i++) {
		copy_v2_v2(tmp_uvdata[i].p, tmp_uvdata[i].sum_co);
		mul_v2_fl(tmp_uvdata[i].p, 1.f / tmp_uvdata[i].ncounter);
	}

	for (i = 0; i < sculptdata->totalUniqueUvs; i++) {
		float dist;
		/* This is supposed to happen only if "Pin Edges" is on, since we have initialization on stroke start
		 * If ever uv brushes get their own mode we should check for toolsettings option too */
		if ((sculptdata->uv[i].flag & MARK_BOUNDARY)) {
			continue;
		}

		sub_v2_v2v2(diff, sculptdata->uv[i].uv, mouse_coord);
		diff[1] /= aspectRatio;
		if ((dist = dot_v2v2(diff, diff)) <= radius) {
			UvElement *element;
			float strength;
			strength = alpha * BKE_brush_curve_strength(brush, sqrt(dist), radius_root);

			sculptdata->uv[i].uv[0] = (1.0f - strength) * sculptdata->uv[i].uv[0] + strength * tmp_uvdata[i].p[0];
			sculptdata->uv[i].uv[1] = (1.0f - strength) * sculptdata->uv[i].uv[1] + strength * tmp_uvdata[i].p[1];

			for (element = sculptdata->uv[i].element; element; element = element->next) {
				MLoopUV *luv;
				BMLoop *l;

				if (element->separate && element != sculptdata->uv[i].element)
					break;

				l = element->l;
				luv = CustomData_bmesh_get(&em->bm->ldata, l->head.data, CD_MLOOPUV);
				copy_v2_v2(luv->uv, sculptdata->uv[i].uv);
			}
		}
	}

	MEM_freeN(tmp_uvdata);

	return;
}


static void uv_sculpt_stroke_apply(bContext *C, wmOperator *op, const wmEvent *event, Object *obedit)
{
	float co[2], radius, radius_root;
	Scene *scene = CTX_data_scene(C);
	ARegion *ar = CTX_wm_region(C);
	BMEditMesh *em = BKE_editmesh_from_object(obedit);
	unsigned int tool;
	UvSculptData *sculptdata = (UvSculptData *)op->customdata;
	SpaceImage *sima;
	int invert;
	int width, height;
	float aspectRatio;
	float alpha, zoomx, zoomy;
	Brush *brush = BKE_paint_brush(sculptdata->uvsculpt);
	ToolSettings *toolsettings = CTX_data_tool_settings(C);
	tool = sculptdata->tool;
	invert = sculptdata->invert ? -1 : 1;
	alpha = BKE_brush_alpha_get(scene, brush);
	UI_view2d_region_to_view(&ar->v2d, event->mval[0], event->mval[1], &co[0], &co[1]);

	sima = CTX_wm_space_image(C);
	ED_space_image_get_size(sima, &width, &height);
	ED_space_image_get_zoom(sima, ar, &zoomx, &zoomy);

	radius = BKE_brush_size_get(scene, brush) / (width * zoomx);
	aspectRatio = width / (float)height;

	/* We will compare squares to save some computation */
	radius = radius * radius;
	radius_root = sqrt(radius);

	/*
	 * Pinch Tool
	 */
	if (tool == UV_SCULPT_TOOL_PINCH) {
		int i;
		alpha *= invert;
		for (i = 0; i < sculptdata->totalUniqueUvs; i++) {
			float dist, diff[2];
			/* This is supposed to happen only if "Lock Borders" is on, since we have initialization on stroke start
			 * If ever uv brushes get their own mode we should check for toolsettings option too */
			if (sculptdata->uv[i].flag & MARK_BOUNDARY) {
				continue;
			}

			sub_v2_v2v2(diff, sculptdata->uv[i].uv, co);
			diff[1] /= aspectRatio;
			if ((dist = dot_v2v2(diff, diff)) <= radius) {
				UvElement *element;
				float strength;
				strength = alpha * BKE_brush_curve_strength(brush, sqrt(dist), radius_root);
				normalize_v2(diff);

				sculptdata->uv[i].uv[0] -= strength * diff[0] * 0.001f;
				sculptdata->uv[i].uv[1] -= strength * diff[1] * 0.001f;

				for (element = sculptdata->uv[i].element; element; element = element->next) {
					MLoopUV *luv;
					BMLoop *l;

					if (element->separate && element != sculptdata->uv[i].element)
						break;

					l = element->l;
					luv = CustomData_bmesh_get(&em->bm->ldata, l->head.data, CD_MLOOPUV);
					copy_v2_v2(luv->uv, sculptdata->uv[i].uv);
				}
			}
		}
	}

	/*
	 * Smooth Tool
	 */
	else if (tool == UV_SCULPT_TOOL_RELAX) {
		unsigned int method = toolsettings->uv_relax_method;
		if (method == UV_SCULPT_TOOL_RELAX_HC) {
			HC_relaxation_iteration_uv(em, sculptdata, co, alpha, radius, aspectRatio);
		}
		else {
			laplacian_relaxation_iteration_uv(em, sculptdata, co, alpha, radius, aspectRatio);
		}
	}

	/*
	 * Grab Tool
	 */
	else if (tool == UV_SCULPT_TOOL_GRAB) {
		int i;
		float diff[2];
		sub_v2_v2v2(diff, co, sculptdata->initial_stroke->init_coord);

		for (i = 0; i < sculptdata->initial_stroke->totalInitialSelected; i++) {
			UvElement *element;
			int uvindex = sculptdata->initial_stroke->initialSelection[i].uv;
			float strength = sculptdata->initial_stroke->initialSelection[i].strength;
			sculptdata->uv[uvindex].uv[0] = sculptdata->initial_stroke->initialSelection[i].initial_uv[0] + strength * diff[0];
			sculptdata->uv[uvindex].uv[1] = sculptdata->initial_stroke->initialSelection[i].initial_uv[1] + strength * diff[1];

			for (element = sculptdata->uv[uvindex].element; element; element = element->next) {
				MLoopUV *luv;
				BMLoop *l;

				if (element->separate && element != sculptdata->uv[uvindex].element)
					break;

				l = element->l;
				luv = CustomData_bmesh_get(&em->bm->ldata, l->head.data, CD_MLOOPUV);
				copy_v2_v2(luv->uv, sculptdata->uv[uvindex].uv);
			}
		}
	}
}


static void uv_sculpt_stroke_exit(bContext *C, wmOperator *op)
{
	UvSculptData *data = op->customdata;
	if (data->timer) {
		WM_event_remove_timer(CTX_wm_manager(C), CTX_wm_window(C), data->timer);
	}
	if (data->elementMap) {
		BM_uv_element_map_free(data->elementMap);
	}
	if (data->uv) {
		MEM_freeN(data->uv);
	}
	if (data->uvedges) {
		MEM_freeN(data->uvedges);
	}
	if (data->initial_stroke) {
		if (data->initial_stroke->initialSelection) {
			MEM_freeN(data->initial_stroke->initialSelection);
		}
		MEM_freeN(data->initial_stroke);
	}

	MEM_freeN(data);
	op->customdata = NULL;
}

static int uv_element_offset_from_face_get(UvElementMap *map, BMFace *efa, BMLoop *l, int island_index, const bool doIslands)
{
	UvElement *element = BM_uv_element_get(map, efa, l);
	if (!element || (doIslands && element->island != island_index)) {
		return -1;
	}
	return element - map->buf;
}


static unsigned int uv_edge_hash(const void *key)
{
	UvEdge *edge = (UvEdge *)key;
	return (BLI_ghashutil_uinthash(edge->uv2) +
	        BLI_ghashutil_uinthash(edge->uv1));
}

static int uv_edge_compare(const void *a, const void *b)
{
	UvEdge *edge1 = (UvEdge *)a;
	UvEdge *edge2 = (UvEdge *)b;

	if ((edge1->uv1 == edge2->uv1) && (edge1->uv2 == edge2->uv2)) {
		return 0;
	}
	return 1;
}


static UvSculptData *uv_sculpt_stroke_init(bContext *C, wmOperator *op, const wmEvent *event)
{
	Scene *scene = CTX_data_scene(C);
	Object *obedit = CTX_data_edit_object(C);
	ToolSettings *ts = scene->toolsettings;
	UvSculptData *data = MEM_callocN(sizeof(*data), "UV Smooth Brush Data");
	BMEditMesh *em = BKE_editmesh_from_object(obedit);
	BMesh *bm = em->bm;

	op->customdata = data;

	curvemapping_initialize(ts->uvsculpt->paint.brush->curve);

	if (data) {
		int counter = 0, i;
		ARegion *ar = CTX_wm_region(C);
		float co[2];
		BMFace *efa;
		MLoopUV *luv;
		BMLoop *l;
		BMIter iter, liter;

		UvEdge *edges;
		GHash *edgeHash;
		GHashIterator *ghi;

		bool do_island_optimization = !(ts->uv_sculpt_settings & UV_SCULPT_ALL_ISLANDS);
		int island_index = 0;
		/* Holds, for each UvElement in elementMap, a pointer to its unique uv.*/
		int *uniqueUv;
		data->tool = (RNA_enum_get(op->ptr, "mode") == BRUSH_STROKE_SMOOTH) ? UV_SCULPT_TOOL_RELAX : ts->uv_sculpt_tool;
		data->invert = (RNA_enum_get(op->ptr, "mode") == BRUSH_STROKE_INVERT) ? 1 : 0;

		data->uvsculpt = &ts->uvsculpt->paint;

		if (do_island_optimization) {
			/* We will need island information */
			if (ts->uv_flag & UV_SYNC_SELECTION) {
				data->elementMap = BM_uv_element_map_create(bm, false, true);
			}
			else {
				data->elementMap = BM_uv_element_map_create(bm, true, true);
			}
		}
		else {
			if (ts->uv_flag & UV_SYNC_SELECTION) {
				data->elementMap = BM_uv_element_map_create(bm, false, false);
			}
			else {
				data->elementMap = BM_uv_element_map_create(bm, true, false);
			}
		}

		if (!data->elementMap) {
			uv_sculpt_stroke_exit(C, op);
			return NULL;
		}

		/* Mouse coordinates, useful for some functions like grab and sculpt all islands */
		UI_view2d_region_to_view(&ar->v2d, event->mval[0], event->mval[1], &co[0], &co[1]);

		/* we need to find the active island here */
		if (do_island_optimization) {
			UvElement *element;
			NearestHit hit;
			Image *ima = CTX_data_edit_image(C);
			uv_find_nearest_vert(scene, ima, em, co, NULL, &hit);

			element = BM_uv_element_get(data->elementMap, hit.efa, hit.l);
			island_index = element->island;
		}


		/* Count 'unique' uvs */
		for (i = 0; i < data->elementMap->totalUVs; i++) {
			if (data->elementMap->buf[i].separate &&
			    (!do_island_optimization || data->elementMap->buf[i].island == island_index))
			{
				counter++;
			}
		}

		/* Allocate the unique uv buffers */
		data->uv = MEM_mallocN(sizeof(*data->uv) * counter, "uv_brush_unique_uvs");
		uniqueUv = MEM_mallocN(sizeof(*uniqueUv) * data->elementMap->totalUVs, "uv_brush_unique_uv_map");
		edgeHash = BLI_ghash_new(uv_edge_hash, uv_edge_compare, "uv_brush_edge_hash");
		/* we have at most totalUVs edges */
		edges = MEM_mallocN(sizeof(*edges) * data->elementMap->totalUVs, "uv_brush_all_edges");
		if (!data->uv || !uniqueUv || !edgeHash || !edges) {
			if (edges) {
				MEM_freeN(edges);
			}
			if (uniqueUv) {
				MEM_freeN(uniqueUv);
			}
			if (edgeHash) {
				BLI_ghash_free(edgeHash, NULL, NULL);
			}
			uv_sculpt_stroke_exit(C, op);
			return NULL;
		}

		data->totalUniqueUvs = counter;
		/* So that we can use this as index for the UvElements */
		counter = -1;
		/* initialize the unique UVs */
		for (i = 0; i < bm->totvert; i++) {
			UvElement *element = data->elementMap->vert[i];
			for (; element; element = element->next) {
				if (element->separate) {
					if (do_island_optimization && (element->island != island_index)) {
						/* skip this uv if not on the active island */
						for (; element->next && !(element->next->separate); element = element->next)
							;
						continue;
					}

					l = element->l;
					luv = CustomData_bmesh_get(&em->bm->ldata, l->head.data, CD_MLOOPUV);

					counter++;
					data->uv[counter].element = element;
					data->uv[counter].flag = 0;
					data->uv[counter].uv = luv->uv;
				}
				/* pointer arithmetic to the rescue, as always :)*/
				uniqueUv[element - data->elementMap->buf] = counter;
			}
		}


		/* Now, on to generate our uv connectivity data */
		counter = 0;
		BM_ITER_MESH (efa, &iter, em->bm, BM_FACES_OF_MESH) {
			BM_ITER_ELEM (l, &liter, efa, BM_LOOPS_OF_FACE) {
				int offset1, itmp1 = uv_element_offset_from_face_get(data->elementMap, efa, l, island_index, do_island_optimization);
				int offset2, itmp2 = uv_element_offset_from_face_get(data->elementMap, efa, l->next, island_index, do_island_optimization);
				char *flag;

				/* Skip edge if not found(unlikely) or not on valid island */
				if (itmp1 == -1 || itmp2 == -1)
					continue;

				offset1 = uniqueUv[itmp1];
				offset2 = uniqueUv[itmp2];

				edges[counter].flag = 0;
				/* using an order policy, sort uvs according to address space. This avoids
				 * Having two different UvEdges with the same uvs on different positions  */
				if (offset1 < offset2) {
					edges[counter].uv1 = offset1;
					edges[counter].uv2 = offset2;
				}
				else {
					edges[counter].uv1 = offset2;
					edges[counter].uv2 = offset1;
				}
				/* Hack! Set the value of the key to its flag. Now we can set the flag when an edge exists twice :) */
				flag = BLI_ghash_lookup(edgeHash, &edges[counter]);
				if (flag) {
					*flag = 1;
				}
				else {
					/* Hack mentioned */
					BLI_ghash_insert(edgeHash, &edges[counter], &edges[counter].flag);
				}
				counter++;
			}
		}

		MEM_freeN(uniqueUv);

		/* Allocate connectivity data, we allocate edges once */
		data->uvedges = MEM_mallocN(sizeof(*data->uvedges) * BLI_ghash_size(edgeHash), "uv_brush_edge_connectivity_data");
		if (!data->uvedges) {
			BLI_ghash_free(edgeHash, NULL, NULL);
			MEM_freeN(edges);
			uv_sculpt_stroke_exit(C, op);
			return NULL;
		}
		ghi = BLI_ghashIterator_new(edgeHash);
		if (!ghi) {
			BLI_ghash_free(edgeHash, NULL, NULL);
			MEM_freeN(edges);
			uv_sculpt_stroke_exit(C, op);
			return NULL;
		}
		/* fill the edges with data */
		for (i = 0; !BLI_ghashIterator_done(ghi); BLI_ghashIterator_step(ghi)) {
			data->uvedges[i++] = *((UvEdge *)BLI_ghashIterator_getKey(ghi));
		}
		data->totalUvEdges = BLI_ghash_size(edgeHash);

		/* cleanup temporary stuff */
		BLI_ghashIterator_free(ghi);
		BLI_ghash_free(edgeHash, NULL, NULL);
		MEM_freeN(edges);

		/* transfer boundary edge property to uvs */
		if (ts->uv_sculpt_settings & UV_SCULPT_LOCK_BORDERS) {
			for (i = 0; i < data->totalUvEdges; i++) {
				if (!data->uvedges[i].flag) {
					data->uv[data->uvedges[i].uv1].flag |= MARK_BOUNDARY;
					data->uv[data->uvedges[i].uv2].flag |= MARK_BOUNDARY;
				}
			}
		}

		/* Allocate initial selection for grab tool */
		if (data->tool == UV_SCULPT_TOOL_GRAB) {
			float radius, radius_root;
			UvSculptData *sculptdata = (UvSculptData *)op->customdata;
			SpaceImage *sima;
			int width, height;
			float aspectRatio;
			float alpha, zoomx, zoomy;
			Brush *brush = BKE_paint_brush(sculptdata->uvsculpt);

			alpha = BKE_brush_alpha_get(scene, brush);

			radius = BKE_brush_size_get(scene, brush);
			sima = CTX_wm_space_image(C);
			ED_space_image_get_size(sima, &width, &height);
			ED_space_image_get_zoom(sima, ar, &zoomx, &zoomy);

			aspectRatio = width / (float)height;
			radius /= (width * zoomx);
			radius = radius * radius;
			radius_root = sqrt(radius);

			/* Allocate selection stack */
			data->initial_stroke = MEM_mallocN(sizeof(*data->initial_stroke), "uv_sculpt_initial_stroke");
			if (!data->initial_stroke) {
				uv_sculpt_stroke_exit(C, op);
			}
			data->initial_stroke->initialSelection = MEM_mallocN(sizeof(*data->initial_stroke->initialSelection) * data->totalUniqueUvs, "uv_sculpt_initial_selection");
			if (!data->initial_stroke->initialSelection) {
				uv_sculpt_stroke_exit(C, op);
			}

			copy_v2_v2(data->initial_stroke->init_coord, co);

			counter = 0;

			for (i = 0; i < data->totalUniqueUvs; i++) {
				float dist, diff[2];
				if (data->uv[i].flag & MARK_BOUNDARY) {
					continue;
				}

				sub_v2_v2v2(diff, data->uv[i].uv, co);
				diff[1] /= aspectRatio;
				if ((dist = dot_v2v2(diff, diff)) <= radius) {
					float strength;
					strength = alpha * BKE_brush_curve_strength(brush, sqrt(dist), radius_root);

					data->initial_stroke->initialSelection[counter].uv = i;
					data->initial_stroke->initialSelection[counter].strength = strength;
					copy_v2_v2(data->initial_stroke->initialSelection[counter].initial_uv, data->uv[i].uv);
					counter++;
				}
			}

			data->initial_stroke->totalInitialSelected = counter;
		}
	}

	return op->customdata;
}

static int uv_sculpt_stroke_invoke(bContext *C, wmOperator *op, const wmEvent *event)
{
	UvSculptData *data;
	Object *obedit = CTX_data_edit_object(C);

	if (!(data = uv_sculpt_stroke_init(C, op, event))) {
		return OPERATOR_CANCELLED;
	}

	uv_sculpt_stroke_apply(C, op, event, obedit);

	data->timer = WM_event_add_timer(CTX_wm_manager(C), CTX_wm_window(C), TIMER, 0.001f);

	if (!data->timer) {
		uv_sculpt_stroke_exit(C, op);
		return OPERATOR_CANCELLED;
	}
	WM_event_add_modal_handler(C, op);

	return OPERATOR_RUNNING_MODAL;
}


static int uv_sculpt_stroke_modal(bContext *C, wmOperator *op, const wmEvent *event)
{
	UvSculptData *data = (UvSculptData *)op->customdata;
	Object *obedit = CTX_data_edit_object(C);

	switch (event->type) {
		case LEFTMOUSE:
		case MIDDLEMOUSE:
		case RIGHTMOUSE:
			uv_sculpt_stroke_exit(C, op);
			return OPERATOR_FINISHED;

		case MOUSEMOVE:
		case INBETWEEN_MOUSEMOVE:
			uv_sculpt_stroke_apply(C, op, event, obedit);
			break;
		case TIMER:
			if (event->customdata == data->timer)
				uv_sculpt_stroke_apply(C, op, event, obedit);
			break;
		default:
			return OPERATOR_RUNNING_MODAL;
	}

	ED_region_tag_redraw(CTX_wm_region(C));
	WM_event_add_notifier(C, NC_GEOM | ND_DATA, obedit->data);
	DAG_id_tag_update(obedit->data, 0);
	return OPERATOR_RUNNING_MODAL;
}

void SCULPT_OT_uv_sculpt_stroke(wmOperatorType *ot)
{
	static EnumPropertyItem stroke_mode_items[] = {
		{BRUSH_STROKE_NORMAL, "NORMAL", 0, "Normal", "Apply brush normally"},
		{BRUSH_STROKE_INVERT, "INVERT", 0, "Invert", "Invert action of brush for duration of stroke"},
		{BRUSH_STROKE_SMOOTH, "RELAX", 0, "Relax", "Switch brush to relax mode for duration of stroke"},
		{0}
	};

	/* identifiers */
	ot->name = "Sculpt UVs";
	ot->description = "Sculpt UVs using a brush";
	ot->idname = "SCULPT_OT_uv_sculpt_stroke";

	/* api callbacks */
	ot->invoke = uv_sculpt_stroke_invoke;
	ot->modal = uv_sculpt_stroke_modal;
	ot->poll = uv_sculpt_poll;

	/* flags */
	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;

	/* props */
	RNA_def_enum(ot->srna, "mode", stroke_mode_items, BRUSH_STROKE_NORMAL, "Mode", "Stroke Mode");
}
