2.5 - Grease Pencil Version 2 (Crude rebirth)

This commit is the start of the new Grease Pencil implementation. I've just ported the old code to make it work with operators, and to store its data in Grease-Pencil datablocks.

However, this is currently still really buggy, with only the barebones of the drawing/creation tools restored (no UI panels, no options). To use (not recommended), use D+S+move_mouse (and click when finished) for now. There are some rather serious event handling errors going on here... 

9 files changed, 1407 insertions, 12 deletions

diff --git a/source/blender/editors/gpencil/drawgpencil.c b/source/blender/editors/gpencil/drawgpencil.c
index 735f1ffddb9..242be943507 100644
--- a/source/blender/editors/gpencil/drawgpencil.c
+++ b/source/blender/editors/gpencil/drawgpencil.c
@@ -933,7 +933,7 @@ void draw_gpencil_2dimage (bContext *C, ImBuf *ibuf)
 	
 	/* check that we have grease-pencil stuff to draw */
 	if (ELEM(NULL, sa, ibuf)) return;
-	gpd= gpencil_data_getactive(sa);
+	gpd= gpencil_data_getactive(C);
 	if (gpd == NULL) return;
 	
 	/* calculate rect */
@@ -1007,7 +1007,7 @@ void draw_gpencil_2dview (bContext *C, short onlyv2d)
 	
 	/* check that we have grease-pencil stuff to draw */
 	if (sa == NULL) return;
-	gpd= gpencil_data_getactive(sa);
+	gpd= gpencil_data_getactive(C);
 	if (gpd == NULL) return;
 	
 	/* draw it! */
@@ -1020,14 +1020,13 @@ void draw_gpencil_2dview (bContext *C, short onlyv2d)
  */
 void draw_gpencil_3dview (bContext *C, short only3d)
 {
-	ScrArea *sa= CTX_wm_area(C);
 	ARegion *ar= CTX_wm_region(C);
 	Scene *scene= CTX_data_scene(C);
 	bGPdata *gpd;
 	int dflag = 0;
 	
 	/* check that we have grease-pencil stuff to draw */
-	gpd= gpencil_data_getactive(sa);
+	gpd= gpencil_data_getactive(C);
 	if (gpd == NULL) return;
 	
 	/* draw it! */
@@ -1047,7 +1046,7 @@ void draw_gpencil_oglrender (bContext *C)
 	
 	/* assume gpencil data comes from v3d */
 	if (v3d == NULL) return;
-	gpd= v3d->gpd;
+	gpd= gpencil_data_getactive(C);
 	if (gpd == NULL) return;
 	
 	/* pass 1: draw 3d-strokes ------------ > */
diff --git a/source/blender/editors/gpencil/gpencil_edit.c b/source/blender/editors/gpencil/gpencil_edit.c
index ef4e09274f2..4480da45572 100644
--- a/source/blender/editors/gpencil/gpencil_edit.c
+++ b/source/blender/editors/gpencil/gpencil_edit.c
@@ -25,6 +25,8 @@
  * ***** END GPL LICENSE BLOCK *****
  */
  
+#if 0 // XXX COMPILE GUARDS FOR OLD CODE
+ 
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
@@ -1697,3 +1699,4 @@ short gpencil_do_paint (bContext *C)
 }
 
 /* ************************************************** */
+#endif // XXX COMPILE GUARDS FOR OLD CODE
diff --git a/source/blender/editors/gpencil/gpencil_intern.h b/source/blender/editors/gpencil/gpencil_intern.h
index 721d8544225..b134328c8a0 100644
--- a/source/blender/editors/gpencil/gpencil_intern.h
+++ b/source/blender/editors/gpencil/gpencil_intern.h
@@ -29,8 +29,20 @@
 #define ED_GPENCIL_INTERN_H
 
 /* internal exports only */
+
+
+/* ***************************************************** */
+/* Operator Defines */
+
+struct wmOperatorType;
+
+/* drawing ---------- */
+
+void GPENCIL_OT_draw(struct wmOperatorType *ot);
+
+
 /******************************************************* */
-/* FILTERED ACTION DATA - TYPES */
+/* FILTERED ACTION DATA - TYPES  ---> XXX DEPRECEATED OLD ANIM SYSTEM CODE! */
 
 /* XXX - TODO: replace this with the modern bAnimListElem... */
 /* This struct defines a structure used for quick access */
diff --git a/source/blender/editors/gpencil/gpencil_ops.c b/source/blender/editors/gpencil/gpencil_ops.c
new file mode 100644
index 00000000000..cb6d66b2fcc
--- /dev/null
+++ b/source/blender/editors/gpencil/gpencil_ops.c
@@ -0,0 +1,68 @@
+/**
+ * $Id: gpencil_ops.c 21617 2009-07-16 04:45:52Z aligorith $
+ *
+ * ***** 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ *
+ * The Original Code is Copyright (C) 2009, Blender Foundation, Joshua Leung
+ * This is a new part of Blender
+ *
+ * Contributor(s): Joshua Leung
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+#include <stdlib.h>
+#include <stddef.h>
+#include <stdio.h>
+
+#include "BLI_blenlib.h"
+
+#include "DNA_windowmanager_types.h" 
+
+#include "WM_api.h"
+#include "WM_types.h"
+
+#include "RNA_access.h"
+#include "RNA_define.h"
+#include "RNA_enum_types.h"
+
+#include "gpencil_intern.h"
+
+/* ****************************************** */
+/* Generic Editing Keymap */
+
+void gpencil_common_keymap(wmWindowManager *wm, ListBase *keymap)
+{
+	wmKeymapItem *km;
+	
+	/* if no keymap provided, use default */
+	if (keymap == NULL)
+		keymap= WM_keymap_listbase(wm, "Grease Pencil Generic", 0, 0);
+	
+	/* Draw */
+	WM_keymap_add_item(keymap, "GPENCIL_OT_draw", SKEY, KM_PRESS, 0, DKEY);
+}
+
+/* ****************************************** */
+
+void ED_operatortypes_gpencil (void)
+{
+	/* Drawing ----------------------- */
+	WM_operatortype_append(GPENCIL_OT_draw);
+}
+
+/* ****************************************** */
diff --git a/source/blender/editors/gpencil/gpencil_paint.c b/source/blender/editors/gpencil/gpencil_paint.c
new file mode 100644
index 00000000000..dc701924b3e
--- /dev/null
+++ b/source/blender/editors/gpencil/gpencil_paint.c
@@ -0,0 +1,1296 @@
+/* Grease Pencil  - version 2
+ * By Joshua Leung
+ */
+
+#include <stdio.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+#include "MEM_guardedalloc.h"
+
+#include "BLI_blenlib.h"
+#include "BLI_arithb.h"
+
+#include "BKE_gpencil.h"
+#include "BKE_context.h"
+#include "BKE_global.h"
+#include "BKE_report.h"
+#include "BKE_utildefines.h"
+
+#include "DNA_gpencil_types.h"
+#include "DNA_action_types.h"
+#include "DNA_object_types.h"
+#include "DNA_scene_types.h"
+#include "DNA_screen_types.h"
+#include "DNA_space_types.h"
+#include "DNA_view2d_types.h"
+#include "DNA_view3d_types.h"
+#include "DNA_windowmanager_types.h"
+
+#include "UI_view2d.h"
+
+#include "ED_armature.h"
+#include "ED_gpencil.h"
+#include "ED_sequencer.h"
+#include "ED_screen.h"
+#include "ED_view3d.h"
+
+#include "RNA_access.h"
+#include "RNA_define.h"
+
+#include "WM_api.h"
+#include "WM_types.h"
+
+#include "gpencil_intern.h"
+
+/* ******************************************* */
+/* Context Wrangling... */
+
+/* Get the active Grease Pencil datablock */
+// TODO: move this to a gpencil_utils.c? 
+bGPdata *gpencil_data_getactive (bContext *C)
+{
+	Scene *scene= CTX_data_scene(C);
+	ScrArea *sa= CTX_wm_area(C);
+	
+	/* if there's an active area, check if the particular editor may
+	 * have defined any special Grease Pencil context for editing...
+	 */
+	if (sa) {
+		switch (sa->spacetype) {
+			case SPACE_VIEW3D: /* 3D-View */
+			{
+				Object *ob= CTX_data_active_object(C);
+				
+				/* just in case... */
+				if (ob) {
+					/* depending on the mode of the object, we may be able to get some GP data 
+					 * from different elements - i.e. bones...
+					 */
+					if (ob->mode & OB_MODE_POSE) {
+						//bPoseChannel *pchan= CTX_data_active_pchan(C);
+						
+						/* if posechannel has GP data, use that... */
+						//if (pchan && pchan->gpd)
+						//	return pchan->gpd;
+					}
+					
+					/* still here, so check if active Object has GP data */
+					//if (ob->gpd)
+					//	return ob->gpd;
+				}
+			}
+				break;
+			
+			case SPACE_NODE: /* Nodes Editor */
+			{
+				//SpaceNode *snode= (SpaceNode *)CTX_wm_space_data(C);
+				
+				/* return the GP data for the active node block/node */
+			}
+				break;
+				
+			case SPACE_SEQ: /* Sequencer */
+			{
+				//SpaceSeq *sseq= (SpaceSeq *)CTX_wm_space_data(C);
+				
+				/* return the GP data for the active strips/image/etc. */
+			}
+				break;
+		}
+	}
+	
+	/* just fall back on the scene's GP data */
+	return (scene) ? scene->gpd : NULL;
+}
+
+
+/* check if context is suitable for drawing */
+static int gpencil_draw_poll (bContext *C)
+{
+	// TODO: must check context for Grease Pencil data...
+	return 1;
+}
+
+/* ******************************************* */
+/* 'Globals' and Defines */
+
+/* Temporary 'Stroke' Operation data */
+typedef struct tGPsdata {
+	Scene *scene;       /* current scene from context */
+	ScrArea *sa;		/* area where painting originated */
+	ARegion *ar;        /* region where painting originated */
+	View2D *v2d;		/* needed for GP_STROKE_2DSPACE */
+	
+#if 0 // XXX review this 2d image stuff...
+	ImBuf *ibuf;		/* needed for GP_STROKE_2DIMAGE */
+	struct IBufViewSettings {
+		int offsx, offsy;			/* offsets */
+		int sizex, sizey;			/* dimensions to use as scale-factor */
+	} im2d_settings;	/* needed for GP_STROKE_2DIMAGE */
+#endif
+	
+	bGPdata *gpd;		/* gp-datablock layer comes from */
+	bGPDlayer *gpl;		/* layer we're working on */
+	bGPDframe *gpf;		/* frame we're working on */
+	
+	short status;		/* current status of painting */
+	short paintmode;	/* mode for painting */
+	
+	int mval[2];		/* current mouse-position */
+	int mvalo[2];		/* previous recorded mouse-position */
+	
+	float pressure;		/* current stylus pressure */
+	float opressure;	/* previous stylus pressure */
+	
+	short radius;		/* radius of influence for eraser */
+	short flags;		/* flags that can get set during runtime */
+} tGPsdata;
+
+/* values for tGPsdata->status */
+enum {
+	GP_STATUS_NORMAL = 0,	/* running normally */
+	GP_STATUS_ERROR,		/* something wasn't correctly set up */
+	GP_STATUS_DONE			/* painting done */
+};
+
+/* values for tGPsdata->paintmode */
+enum {
+	GP_PAINTMODE_DRAW = 0,
+	GP_PAINTMODE_ERASER
+};
+
+/* Return flags for adding points to stroke buffer */
+enum {
+	GP_STROKEADD_INVALID	= -2,		/* error occurred - insufficient info to do so */
+	GP_STROKEADD_OVERFLOW	= -1,		/* error occurred - cannot fit any more points */
+	GP_STROKEADD_NORMAL,				/* point was successfully added */
+	GP_STROKEADD_FULL					/* cannot add any more points to buffer */
+};
+
+/* Runtime flags */
+enum {
+	GP_PAINTFLAG_FIRSTRUN		= (1<<0),	/* operator just started */
+	GP_PAINTFLAG_STRAIGHTLINES	= (1<<1),	/* only take the endpoints of a stroke */
+};
+
+/* ------ */
+
+/* maximum sizes of gp-session buffer */
+#define GP_STROKE_BUFFER_MAX	5000
+
+/* Macros for accessing sensitivity thresholds... */
+	/* minimum number of pixels mouse should move before new point created */
+#define MIN_MANHATTEN_PX	(U.gp_manhattendist)
+	/* minimum length of new segment before new point can be added */
+#define MIN_EUCLIDEAN_PX	(U.gp_euclideandist)
+
+/* macro to test if only converting endpoints - only for use when converting!  */	
+// XXX for now, don't test for editpaint too...
+//#define GP_BUFFER2STROKE_ENDPOINTS ((gpd->flag & GP_DATA_EDITPAINT) && (p->flags & GP_PAINTFLAG_STRAIGHTLINES))
+#define GP_BUFFER2STROKE_ENDPOINTS ((p->flags & GP_PAINTFLAG_STRAIGHTLINES))
+
+/* ------ */
+/* Forward defines for some functions... */
+
+static void gp_session_validatebuffer(tGPsdata *p);
+
+/* ******************************************* */
+/* Calculations/Conversions */
+
+/* Stroke Editing ---------------------------- */
+
+/* check if the current mouse position is suitable for adding a new point */
+static short gp_stroke_filtermval (tGPsdata *p, int mval[2], int pmval[2])
+{
+	int dx= abs(mval[0] - pmval[0]);
+	int dy= abs(mval[1] - pmval[1]);
+	
+	/* check if mouse moved at least certain distance on both axes (best case) */
+	if ((dx > MIN_MANHATTEN_PX) && (dy > MIN_MANHATTEN_PX))
+		return 1;
+	
+	/* check if the distance since the last point is significant enough */
+	// future optimisation: sqrt here may be too slow?
+	else if (sqrt(dx*dx + dy*dy) > MIN_EUCLIDEAN_PX)
+		return 1;
+	
+	/* mouse 'didn't move' */
+	else
+		return 0;
+}
+
+/* convert screen-coordinates to buffer-coordinates */
+// XXX this method needs a total overhaul!
+static void gp_stroke_convertcoords (tGPsdata *p, short mval[], float out[])
+{
+	bGPdata *gpd= p->gpd;
+	
+	/* in 3d-space - pt->x/y/z are 3 side-by-side floats */
+	if (gpd->sbuffer_sflag & GP_STROKE_3DSPACE) {
+		View3D *v3d= p->sa->spacedata.first;
+		const short mx=mval[0], my=mval[1];
+		float *fp= give_cursor(p->scene, v3d); // XXX NULL could be v3d
+		float dvec[3];
+		
+		/* Current method just converts each point in screen-coordinates to 
+		 * 3D-coordinates using the 3D-cursor as reference. In general, this 
+		 * works OK, but it could of course be improved.
+		 *
+		 * TODO:
+		 *	- investigate using nearest point(s) on a previous stroke as
+		 *	  reference point instead or as offset, for easier stroke matching
+		 *	- investigate projection onto geometry (ala retopo)
+		 */
+		
+		/* method taken from editview.c - mouse_cursor() */
+		project_short_noclip(p->ar, fp, mval);
+		window_to_3d_delta(p->ar, dvec, mval[0]-mx, mval[1]-my);
+		VecSubf(out, fp, dvec);
+	}
+	
+	/* 2d - on 'canvas' (assume that p->v2d is set) */
+	else if ((gpd->sbuffer_sflag & GP_STROKE_2DSPACE) && (p->v2d)) {
+		float x, y;
+		
+		UI_view2d_region_to_view(p->v2d, mval[0], mval[1], &x, &y);
+		
+		out[0]= x;
+		out[1]= y;
+	}
+	
+#if 0
+	/* 2d - on image 'canvas' (assume that p->v2d is set) */
+	else if (gpd->sbuffer_sflag & GP_STROKE_2DIMAGE) {
+		int sizex, sizey, offsx, offsy;
+		
+		/* get stored settings 
+		 *	- assume that these have been set already (there are checks that set sane 'defaults' just in case)
+		 */
+		sizex= p->im2d_settings.sizex;
+		sizey= p->im2d_settings.sizey;
+		offsx= p->im2d_settings.offsx;
+		offsy= p->im2d_settings.offsy;
+		
+		/* calculate new points */
+		out[0]= (float)(mval[0] - offsx) / (float)sizex;
+		out[1]= (float)(mval[1] - offsy) / (float)sizey;
+	}
+#endif
+	
+	/* 2d - relative to screen (viewport area) */
+	else {
+		out[0] = (float)(mval[0]) / (float)(p->sa->winx) * 1000;
+		out[1] = (float)(mval[1]) / (float)(p->sa->winy) * 1000;
+	}
+}
+
+/* add current stroke-point to buffer (returns whether point was successfully added) */
+static short gp_stroke_addpoint (tGPsdata *p, int mval[2], float pressure)
+{
+	bGPdata *gpd= p->gpd;
+	tGPspoint *pt;
+	
+	/* check if still room in buffer */
+	if (gpd->sbuffer_size >= GP_STROKE_BUFFER_MAX)
+		return GP_STROKEADD_OVERFLOW;
+	
+	/* get pointer to destination point */
+	pt= ((tGPspoint *)(gpd->sbuffer) + gpd->sbuffer_size);
+	
+	/* store settings */
+	pt->x= mval[0];
+	pt->y= mval[1];
+	pt->pressure= pressure;
+	
+	/* increment counters */
+	gpd->sbuffer_size++;
+	
+	/* check if another operation can still occur */
+	if (gpd->sbuffer_size == GP_STROKE_BUFFER_MAX)
+		return GP_STROKEADD_FULL;
+	else
+		return GP_STROKEADD_NORMAL;
+}
+
+/* smooth a stroke (in buffer) before storing it */
+static void gp_stroke_smooth (tGPsdata *p)
+{
+	bGPdata *gpd= p->gpd;
+	int i=0, cmx=gpd->sbuffer_size;
+	
+	/* only smooth if smoothing is enabled, and we're not doing a straight line */
+	if (!(U.gp_settings & GP_PAINT_DOSMOOTH) || GP_BUFFER2STROKE_ENDPOINTS)
+		return;
+	
+	/* don't try if less than 2 points in buffer */
+	if ((cmx <= 2) || (gpd->sbuffer == NULL))
+		return;
+	
+	/* apply weighting-average (note doing this along path sequentially does introduce slight error) */
+	for (i=0; i < gpd->sbuffer_size; i++) {
+		tGPspoint *pc= (((tGPspoint *)gpd->sbuffer) + i);
+		tGPspoint *pb= (i-1 > 0)?(pc-1):(pc);
+		tGPspoint *pa= (i-2 > 0)?(pc-2):(pb);
+		tGPspoint *pd= (i+1 < cmx)?(pc+1):(pc);
+		tGPspoint *pe= (i+2 < cmx)?(pc+2):(pd);
+		
+		pc->x= (short)(0.1*pa->x + 0.2*pb->x + 0.4*pc->x + 0.2*pd->x + 0.1*pe->x);
+		pc->y= (short)(0.1*pa->y + 0.2*pb->y + 0.4*pc->y + 0.2*pd->y + 0.1*pe->y);
+	}
+}
+
+/* simplify a stroke (in buffer) before storing it 
+ *	- applies a reverse Chaikin filter
+ *	- code adapted from etch-a-ton branch (editarmature_sketch.c)
+ */
+static void gp_stroke_simplify (tGPsdata *p)
+{
+	bGPdata *gpd= p->gpd;
+	tGPspoint *old_points= (tGPspoint *)gpd->sbuffer;
+	short num_points= gpd->sbuffer_size;
+	short flag= gpd->sbuffer_sflag;
+	short i, j;
+	
+	/* only simplify if simlification is enabled, and we're not doing a straight line */
+	if (!(U.gp_settings & GP_PAINT_DOSIMPLIFY) || GP_BUFFER2STROKE_ENDPOINTS)
+		return;
+	
+	/* don't simplify if less than 4 points in buffer */
+	if ((num_points <= 2) || (old_points == NULL))
+		return;
+		
+	/* clear buffer (but don't free mem yet) so that we can write to it 
+	 *	- firstly set sbuffer to NULL, so a new one is allocated
+	 *	- secondly, reset flag after, as it gets cleared auto
+	 */
+	gpd->sbuffer= NULL;
+	gp_session_validatebuffer(p);
+	gpd->sbuffer_sflag = flag;
+	
+/* macro used in loop to get position of new point
+ *	- used due to the mixture of datatypes in use here
+ */
+#define GP_SIMPLIFY_AVPOINT(offs, sfac) \
+	{ \
+		co[0] += (float)(old_points[offs].x * sfac); \
+		co[1] += (float)(old_points[offs].y * sfac); \
+		pressure += old_points[offs].pressure * sfac; \
+	}
+	
+	for (i = 0, j = 0; i < num_points; i++)
+	{
+		if (i - j == 3)
+		{
+			float co[2], pressure;
+			int mco[2];
+			
+			/* initialise values */
+			co[0]= 0;
+			co[1]= 0;
+			pressure = 0;
+			
+			/* using macro, calculate new point */
+			GP_SIMPLIFY_AVPOINT(j, -0.25f);
+			GP_SIMPLIFY_AVPOINT(j+1, 0.75f);
+			GP_SIMPLIFY_AVPOINT(j+2, 0.75f);
+			GP_SIMPLIFY_AVPOINT(j+3, -0.25f);
+			
+			/* set values for adding */
+			mco[0]= (int)co[0];
+			mco[1]= (int)co[1];
+			
+			/* ignore return values on this... assume to be ok for now */
+			gp_stroke_addpoint(p, mco, pressure);
+			
+			j += 2;
+		}
+	} 
+	
+	/* free old buffer */
+	MEM_freeN(old_points);
+}
+
+
+/* make a new stroke from the buffer data */
+static void gp_stroke_newfrombuffer (tGPsdata *p)
+{
+	bGPdata *gpd= p->gpd;
+	bGPDstroke *gps;
+	bGPDspoint *pt;
+	tGPspoint *ptc;
+	int i, totelem;
+	
+	/* get total number of points to allocate space for:
+	 *	- in 'Draw Mode', holding the Ctrl-Modifier will only take endpoints
+	 *	- otherwise, do whole stroke
+	 */
+	if (GP_BUFFER2STROKE_ENDPOINTS)
+		totelem = (gpd->sbuffer_size >= 2) ? 2: gpd->sbuffer_size;
+	else
+		totelem = gpd->sbuffer_size;
+	
+	/* exit with error if no valid points from this stroke */
+	if (totelem == 0) {
+		if (G.f & G_DEBUG) 
+			printf("Error: No valid points in stroke buffer to convert (tot=%d) \n", gpd->sbuffer_size);
+		return;
+	}
+	
+	/* allocate memory for a new stroke */
+	gps= MEM_callocN(sizeof(bGPDstroke), "gp_stroke");
+	
+	/* allocate enough memory for a continuous array for storage points */
+	pt= gps->points= MEM_callocN(sizeof(bGPDspoint)*totelem, "gp_stroke_points");
+	
+	/* copy appropriate settings for stroke */
+	gps->totpoints= totelem;
+	gps->thickness= p->gpl->thickness;
+	gps->flag= gpd->sbuffer_sflag;
+	
+	/* copy points from the buffer to the stroke */
+	if (GP_BUFFER2STROKE_ENDPOINTS) {
+		/* 'Draw Mode' + Ctrl-Modifier - only endpoints */
+		{
+			/* first point */
+			ptc= gpd->sbuffer;
+			
+			/* convert screen-coordinates to appropriate coordinates (and store them) */
+			gp_stroke_convertcoords(p, &ptc->x, &pt->x);
+			
+			/* copy pressure */
+			pt->pressure= ptc->pressure;
+			
+			pt++;
+		}
+			
+		if (totelem == 2) {
+			/* last point if applicable */
+			ptc= ((tGPspoint *)gpd->sbuffer) + (gpd->sbuffer_size - 1);
+			
+			/* convert screen-coordinates to appropriate coordinates (and store them) */
+			gp_stroke_convertcoords(p, &ptc->x, &pt->x);
+			
+			/* copy pressure */
+			pt->pressure= ptc->pressure;
+		}
+	}
+	else {
+		/* convert all points (normal behaviour) */
+		for (i=0, ptc=gpd->sbuffer; i < gpd->sbuffer_size && ptc; i++, ptc++) {
+			/* convert screen-coordinates to appropriate coordinates (and store them) */
+			gp_stroke_convertcoords(p, &ptc->x, &pt->x);
+			
+			/* copy pressure */
+			pt->pressure= ptc->pressure;
+			
+			pt++;
+		}
+	}
+	
+	/* add stroke to frame */
+	BLI_addtail(&p->gpf->strokes, gps);
+}
+
+/* --- 'Eraser' for 'Paint' Tool ------ */
+
+/* eraser tool - remove segment from stroke/split stroke (after lasso inside) */
+static short gp_stroke_eraser_splitdel (bGPDframe *gpf, bGPDstroke *gps, int i)
+{
+	bGPDspoint *pt_tmp= gps->points;
+	bGPDstroke *gsn = NULL;
+
+	/* if stroke only had two points, get rid of stroke */
+	if (gps->totpoints == 2) {
+		/* free stroke points, then stroke */
+		MEM_freeN(pt_tmp);
+		BLI_freelinkN(&gpf->strokes, gps);
+		
+		/* nothing left in stroke, so stop */
+		return 1;
+	}
+
+	/* if last segment, just remove segment from the stroke */
+	else if (i == gps->totpoints - 2) {
+		/* allocate new points array, and assign most of the old stroke there */
+		gps->totpoints--;
+		gps->points= MEM_callocN(sizeof(bGPDspoint)*gps->totpoints, "gp_stroke_points");
+		memcpy(gps->points, pt_tmp, sizeof(bGPDspoint)*gps->totpoints);
+		
+		/* free temp buffer */
+		MEM_freeN(pt_tmp);
+		
+		/* nothing left in stroke, so stop */
+		return 1;
+	}
+
+	/* if first segment, just remove segment from the stroke */
+	else if (i == 0) {
+		/* allocate new points array, and assign most of the old stroke there */
+		gps->totpoints--;
+		gps->points= MEM_callocN(sizeof(bGPDspoint)*gps->totpoints, "gp_stroke_points");
+		memcpy(gps->points, pt_tmp + 1, sizeof(bGPDspoint)*gps->totpoints);
+		
+		/* free temp buffer */
+		MEM_freeN(pt_tmp);
+		
+		/* no break here, as there might still be stuff to remove in this stroke */
+		return 0;
+	}
+
+	/* segment occurs in 'middle' of stroke, so split */
+	else {
+		/* duplicate stroke, and assign 'later' data to that stroke */
+		gsn= MEM_dupallocN(gps);
+		gsn->prev= gsn->next= NULL;
+		BLI_insertlinkafter(&gpf->strokes, gps, gsn);
+		
+		gsn->totpoints= gps->totpoints - i;
+		gsn->points= MEM_callocN(sizeof(bGPDspoint)*gsn->totpoints, "gp_stroke_points");
+		memcpy(gsn->points, pt_tmp + i, sizeof(bGPDspoint)*gsn->totpoints);
+		
+		/* adjust existing stroke  */
+		gps->totpoints= i;
+		gps->points= MEM_callocN(sizeof(bGPDspoint)*gps->totpoints, "gp_stroke_points");
+		memcpy(gps->points, pt_tmp, sizeof(bGPDspoint)*i);
+		
+		/* free temp buffer */
+		MEM_freeN(pt_tmp);
+		
+		/* nothing left in stroke, so stop */
+		return 1;
+	}
+}
+
+/* eraser tool - check if part of stroke occurs within last segment drawn by eraser */
+static short gp_stroke_eraser_strokeinside (int mval[], int mvalo[], short rad, short x0, short y0, short x1, short y1)
+{
+	/* simple within-radius check for now */
+	if (edge_inside_circle(mval[0], mval[1], rad, x0, y0, x1, y1))
+		return 1;
+	
+	/* not inside */
+	return 0;
+} 
+
+/* eraser tool - evaluation per stroke */
+// TODO: this could really do with some optimisation (KD-Tree/BVH?)
+static void gp_stroke_eraser_dostroke (tGPsdata *p, int mval[], int mvalo[], short rad, rcti *rect, bGPDframe *gpf, bGPDstroke *gps)
+{
+	bGPDspoint *pt1, *pt2;
+	int x0=0, y0=0, x1=0, y1=0;
+	short xyval[2];
+	int i;
+	
+	if (gps->totpoints == 0) {
+		/* just free stroke */
+		if (gps->points) 
+			MEM_freeN(gps->points);
+		BLI_freelinkN(&gpf->strokes, gps);
+	}
+	else if (gps->totpoints == 1) {
+		/* get coordinates */
+		if (gps->flag & GP_STROKE_3DSPACE) {
+			project_short(p->ar, &gps->points->x, xyval);
+			x0= xyval[0];
+			y0= xyval[1];
+		}
+		else if (gps->flag & GP_STROKE_2DSPACE) {			
+			UI_view2d_view_to_region(p->v2d, gps->points->x, gps->points->y, &x0, &y0);
+		}
+#if 0
+		else if (gps->flag & GP_STROKE_2DIMAGE) {			
+			int offsx, offsy, sizex, sizey;
+			
+			/* get stored settings */
+			sizex= p->im2d_settings.sizex;
+			sizey= p->im2d_settings.sizey;
+			offsx= p->im2d_settings.offsx;
+			offsy= p->im2d_settings.offsy;
+			
+			/* calculate new points */
+			x0= (int)((gps->points->x * sizex) + offsx);
+			y0= (int)((gps->points->y * sizey) + offsy);
+		}
+#endif
+		else {
+			x0= (int)(gps->points->x / 1000 * p->sa->winx);
+			y0= (int)(gps->points->y / 1000 * p->sa->winy);
+		}
+		
+		/* do boundbox check first */
+		if (BLI_in_rcti(rect, x0, y0)) {
+			/* only check if point is inside */
+			if ( ((x0-mval[0])*(x0-mval[0]) + (y0-mval[1])*(y0-mval[1])) <= rad*rad ) {
+				/* free stroke */
+				MEM_freeN(gps->points);
+				BLI_freelinkN(&gpf->strokes, gps);
+			}
+		}
+	}
+	else {	
+		/* loop over the points in the stroke, checking for intersections 
+		 * 	- an intersection will require the stroke to be split
+		 */
+		for (i=0; (i+1) < gps->totpoints; i++) {
+			/* get points to work with */
+			pt1= gps->points + i;
+			pt2= gps->points + i + 1;
+			
+			/* get coordinates */
+			if (gps->flag & GP_STROKE_3DSPACE) {
+				project_short(p->ar, &pt1->x, xyval);
+				x0= xyval[0];
+				y0= xyval[1];
+				
+				project_short(p->ar, &pt2->x, xyval);
+				x1= xyval[0];
+				y1= xyval[1];
+			}
+			else if (gps->flag & GP_STROKE_2DSPACE) {
+				UI_view2d_view_to_region(p->v2d, pt1->x, pt1->y, &x0, &y0);
+				
+				UI_view2d_view_to_region(p->v2d, pt2->x, pt2->y, &x1, &y1);
+			}
+#if 0
+			else if (gps->flag & GP_STROKE_2DIMAGE) {
+				int offsx, offsy, sizex, sizey;
+				
+				/* get stored settings */
+				sizex= p->im2d_settings.sizex;
+				sizey= p->im2d_settings.sizey;
+				offsx= p->im2d_settings.offsx;
+				offsy= p->im2d_settings.offsy;
+				
+				/* calculate new points */
+				x0= (int)((pt1->x * sizex) + offsx);
+				y0= (int)((pt1->y * sizey) + offsy);
+				
+				x1= (int)((pt2->x * sizex) + offsx);
+				y1= (int)((pt2->y * sizey) + offsy);
+			}
+#endif
+			else {
+				x0= (int)(pt1->x / 1000 * p->sa->winx);
+				y0= (int)(pt1->y / 1000 * p->sa->winy);
+				x1= (int)(pt2->x / 1000 * p->sa->winx);
+				y1= (int)(pt2->y / 1000 * p->sa->winy);
+			}
+			
+			/* check that point segment of the boundbox of the eraser stroke */
+			if (BLI_in_rcti(rect, x0, y0) || BLI_in_rcti(rect, x1, y1)) {
+				/* check if point segment of stroke had anything to do with
+				 * eraser region  (either within stroke painted, or on its lines)
+				 * 	- this assumes that linewidth is irrelevant
+				 */
+				if (gp_stroke_eraser_strokeinside(mval, mvalo, rad, x0, y0, x1, y1)) {
+					/* if function returns true, break this loop (as no more point to check) */
+					if (gp_stroke_eraser_splitdel(gpf, gps, i))
+						break;
+				}
+			}
+		}
+	}
+}
+
+/* erase strokes which fall under the eraser strokes */
+static void gp_stroke_doeraser (tGPsdata *p)
+{
+	bGPDframe *gpf= p->gpf;
+	bGPDstroke *gps, *gpn;
+	rcti rect;
+	
+	/* rect is rectangle of eraser */
+	rect.xmin= p->mval[0] - p->radius;
+	rect.ymin= p->mval[1] - p->radius;
+	rect.xmax= p->mval[0] + p->radius;
+	rect.ymax= p->mval[1] + p->radius;
+	
+	/* loop over strokes, checking segments for intersections */
+	for (gps= gpf->strokes.first; gps; gps= gpn) {
+		gpn= gps->next;
+		gp_stroke_eraser_dostroke(p, p->mval, p->mvalo, p->radius, &rect, gpf, gps);
+	}
+}
+
+/* ******************************************* */
+/* Sketching Operator */
+
+/* clear the session buffers (call this before AND after a paint operation) */
+static void gp_session_validatebuffer (tGPsdata *p)
+{
+	bGPdata *gpd= p->gpd;
+	
+	/* clear memory of buffer (or allocate it if starting a new session) */
+	if (gpd->sbuffer)
+		memset(gpd->sbuffer, 0, sizeof(tGPspoint)*GP_STROKE_BUFFER_MAX);
+	else
+		gpd->sbuffer= MEM_callocN(sizeof(tGPspoint)*GP_STROKE_BUFFER_MAX, "gp_session_strokebuffer");
+	
+	/* reset indices */
+	gpd->sbuffer_size = 0;
+	
+	/* reset flags */
+	gpd->sbuffer_sflag= 0;
+}
+
+/* init new painting session */
+static tGPsdata *gp_session_initpaint (bContext *C)
+{
+	tGPsdata *p = NULL;
+	ScrArea *curarea= CTX_wm_area(C);
+	ARegion *ar= CTX_wm_region(C);
+	
+	/* make sure the active view (at the starting time) is a 3d-view */
+	if (curarea == NULL) {
+		if (G.f & G_DEBUG) 
+			printf("Error: No active view for painting \n");
+		return NULL;
+	}
+	
+	/* create new context data */
+	p= MEM_callocN(sizeof(tGPsdata), "GPencil Drawing Data");
+	
+	/* pass on current scene */
+	p->scene= CTX_data_scene(C);
+	
+	switch (curarea->spacetype) {
+		/* supported views first */
+		case SPACE_VIEW3D:
+		{
+			//View3D *v3d= curarea->spacedata.first;
+			
+			/* set current area */
+			p->sa= curarea;
+			p->ar= ar;
+			
+#if 0 // XXX will this sort of antiquated stuff be restored?
+			/* check that gpencil data is allowed to be drawn */
+			if ((v3d->flag2 & V3D_DISPGP)==0) {
+				p->status= GP_STATUS_ERROR;
+				if (G.f & G_DEBUG) 
+					printf("Error: In active view, Grease Pencil not shown \n");
+				return p;
+			}
+#endif
+		}
+			break;
+#if 0 // XXX these other spaces will come over time...
+		case SPACE_NODE:
+		{
+			SpaceNode *snode= curarea->spacedata.first;
+			
+			/* set current area */
+			p->sa= curarea;
+			p->ar= ar;
+			p->v2d= &ar->v2d;
+			
+			/* check that gpencil data is allowed to be drawn */
+			if ((snode->flag & SNODE_DISPGP)==0) {
+				p->status= GP_STATUS_ERROR;
+				if (G.f & G_DEBUG) 
+					printf("Error: In active view, Grease Pencil not shown \n");
+				return;
+			}
+		}
+			break;
+		case SPACE_SEQ:
+		{
+			SpaceSeq *sseq= curarea->spacedata.first;
+			
+			/* set current area */
+			p->sa= curarea;
+			p->ar= ar;
+			p->v2d= &ar->v2d;
+			
+			/* check that gpencil data is allowed to be drawn */
+			if (sseq->mainb == SEQ_DRAW_SEQUENCE) {
+				p->status= GP_STATUS_ERROR;
+				if (G.f & G_DEBUG) 
+					printf("Error: In active view (sequencer), active mode doesn't support Grease Pencil \n");
+				return;
+			}
+			if ((sseq->flag & SEQ_DRAW_GPENCIL)==0) {
+				p->status= GP_STATUS_ERROR;
+				if (G.f & G_DEBUG) 
+					printf("Error: In active view, Grease Pencil not shown \n");
+				return;
+			}
+		}
+			break;	
+		case SPACE_IMAGE:
+		{
+			SpaceImage *sima= curarea->spacedata.first;
+			
+			/* set the current area */
+			p->sa= curarea;
+			p->ar= ar;
+			p->v2d= &ar->v2d;
+			p->ibuf= BKE_image_get_ibuf(sima->image, &sima->iuser);
+			
+			/* check that gpencil data is allowed to be drawn */
+			if ((sima->flag & SI_DISPGP)==0) {
+				p->status= GP_STATUS_ERROR;
+				if (G.f & G_DEBUG)
+					printf("Error: In active view, Grease Pencil not shown \n");
+				return;
+			}
+		}
+			break;
+#endif
+		/* unsupported views */
+		default:
+		{
+			p->status= GP_STATUS_ERROR;
+			if (G.f & G_DEBUG) 
+				printf("Error: Active view not appropriate for Grease Pencil drawing \n");
+			return p;
+		}
+			break;
+	}
+	
+	/* get gp-data */
+	p->gpd= gpencil_data_getactive(C);
+	if (p->gpd == NULL) {
+		/* add new GPencil block for the active scene for now... */
+		p->gpd= gpencil_data_addnew("GPencil");
+		p->scene->gpd= p->gpd;
+	}
+	
+	/* set edit flags */
+	G.f |= G_GREASEPENCIL;
+	
+	/* set initial run flag */
+	p->flags |= GP_PAINTFLAG_FIRSTRUN;
+	
+	/* clear out buffer (stored in gp-data), in case something contaminated it */
+	gp_session_validatebuffer(p);
+	
+#if 0
+	/* set 'default' im2d_settings just in case something that uses this doesn't set it */
+	p->im2d_settings.sizex= 1;
+	p->im2d_settings.sizey= 1;
+#endif
+	
+	/* return context data for running paint operator */
+	return p;
+}
+
+/* cleanup after a painting session */
+static void gp_session_cleanup (tGPsdata *p)
+{
+	bGPdata *gpd= (p) ? p->gpd : NULL;
+	
+	/* error checking */
+	if (gpd == NULL)
+		return;
+	
+	/* free stroke buffer */
+	if (gpd->sbuffer) {
+		MEM_freeN(gpd->sbuffer);
+		gpd->sbuffer= NULL;
+	}
+	
+	/* clear flags */
+	gpd->sbuffer_size= 0;
+	gpd->sbuffer_sflag= 0;
+}
+
+/* init new stroke */
+static void gp_paint_initstroke (tGPsdata *p, short paintmode)
+{	
+	/* get active layer (or add a new one if non-existent) */
+	p->gpl= gpencil_layer_getactive(p->gpd);
+	if (p->gpl == NULL)
+		p->gpl= gpencil_layer_addnew(p->gpd);
+	if (p->gpl->flag & GP_LAYER_LOCKED) {
+		p->status= GP_STATUS_ERROR;
+		if (G.f & G_DEBUG)
+			printf("Error: Cannot paint on locked layer \n");
+		return;
+	}
+		
+	/* get active frame (add a new one if not matching frame) */
+	p->gpf= gpencil_layer_getframe(p->gpl, p->scene->r.cfra, 1);
+	if (p->gpf == NULL) {
+		p->status= GP_STATUS_ERROR;
+		if (G.f & G_DEBUG) 
+			printf("Error: No frame created (gpencil_paint_init) \n");
+		return;
+	}
+	else
+		p->gpf->flag |= GP_FRAME_PAINT;
+	
+	/* set 'eraser' for this stroke if using eraser */
+	p->paintmode= paintmode;
+	if (p->paintmode == GP_PAINTMODE_ERASER)
+		p->gpd->sbuffer_sflag |= GP_STROKE_ERASER;
+	
+	/* check if points will need to be made in view-aligned space */
+	// XXX this should be the default? this is something that needs review
+	/*if (p->gpd->flag & GP_DATA_VIEWALIGN)*/ {
+		switch (p->sa->spacetype) {
+			case SPACE_VIEW3D:
+			{
+				View3D *v3d= (View3D *)p->sa->spacedata.first;
+				RegionView3D *rv3d= p->ar->regiondata;
+				
+				// TODO: this should only happen for scene... otherwise use object center!
+				float *fp= give_cursor(p->scene, v3d);
+				initgrabz(rv3d, fp[0], fp[1], fp[2]);
+				
+				p->gpd->sbuffer_sflag |= GP_STROKE_3DSPACE;
+			}
+				break;
+#if 0 // XXX other spacetypes to be restored in due course
+			case SPACE_NODE:
+			{
+				p->gpd->sbuffer_sflag |= GP_STROKE_2DSPACE;
+			}
+				break;
+			case SPACE_SEQ:
+			{
+				SpaceSeq *sseq= (SpaceSeq *)p->sa->spacedata.first;
+				int rectx, recty;
+				float zoom, zoomx, zoomy;
+				
+				/* set draw 2d-stroke flag */
+				p->gpd->sbuffer_sflag |= GP_STROKE_2DIMAGE;
+				
+				/* calculate zoom factor */
+				zoom= (float)(SEQ_ZOOM_FAC(sseq->zoom));
+				if (sseq->mainb == SEQ_DRAW_IMG_IMBUF) {
+					zoomx = zoom * ((float)p->scene->r.xasp / (float)p->scene->r.yasp);
+					zoomy = zoom;
+				} 
+				else
+					zoomx = zoomy = zoom;
+				
+				/* calculate rect size to use to calculate the size of the drawing area
+				 *	- We use the size of the output image not the size of the ibuf being shown
+				 *	  as it is too messy getting the ibuf (and could be too slow). This should be
+				 *	  a reasonable for most cases anyway.
+				 */
+				rectx= (p->scene->r.size * p->scene->r.xsch) / 100;
+				recty= (p->scene->r.size * p->scene->r.ysch) / 100; 
+				
+				/* set offset and scale values for opertations to use */
+				p->im2d_settings.sizex= (int)(zoomx * rectx);
+				p->im2d_settings.sizey= (int)(zoomy * recty);
+				p->im2d_settings.offsx= (int)((p->sa->winx-p->im2d_settings.sizex)/2 + sseq->xof);
+				p->im2d_settings.offsy= (int)((p->sa->winy-p->im2d_settings.sizey)/2 + sseq->yof);
+			}
+				break;
+			case SPACE_IMAGE:
+			{
+				/* check if any ibuf available */
+				if (p->ibuf)
+					p->gpd->sbuffer_sflag |= GP_STROKE_2DSPACE;
+			}
+				break;
+#endif
+		}
+	}
+}
+
+/* finish off a stroke (clears buffer, but doesn't finish the paint operation) */
+static void gp_paint_strokeend (tGPsdata *p)
+{
+	/* check if doing eraser or not */
+	if ((p->gpd->sbuffer_sflag & GP_STROKE_ERASER) == 0) {
+		/* smooth stroke before transferring? */
+		gp_stroke_smooth(p);
+		
+		/* simplify stroke before transferring? */
+		gp_stroke_simplify(p);
+		
+		/* transfer stroke to frame */
+		gp_stroke_newfrombuffer(p);
+	}
+	
+	/* clean up buffer now */
+	gp_session_validatebuffer(p);
+}
+
+/* finish off stroke painting operation */
+static void gp_paint_cleanup (tGPsdata *p)
+{
+	/* finish off a stroke */
+	gp_paint_strokeend(p);
+	
+	/* "unlock" frame */
+	p->gpf->flag &= ~GP_FRAME_PAINT;
+}
+
+/* ------------------------------- */
+
+
+static int gpencil_draw_init (bContext *C, wmOperator *op)
+{
+	tGPsdata *p;
+	int paintmode= RNA_enum_get(op->ptr, "mode");
+	
+	/* check context */
+	p= op->customdata= gp_session_initpaint(C);
+	if ((p == NULL) || (p->status == GP_STATUS_ERROR)) {
+		/* something wasn't set correctly in context */
+		gp_session_cleanup(p);
+		return 0;
+	}
+	
+	/* init painting data */
+	gp_paint_initstroke(p, paintmode);
+	if (p->status == GP_STATUS_ERROR) {
+		gp_session_cleanup(p);
+		return 0;
+	}
+	
+	/* radius for eraser circle is defined in userprefs now */
+	// TODO: make this more easily tweaked... 
+	p->radius= U.gp_eraser;
+	
+	/* everything is now setup ok */
+	return 1;
+}
+
+/* ------------------------------- */
+
+static void gpencil_draw_exit (bContext *C, wmOperator *op)
+{
+	tGPsdata *p= op->customdata;
+	
+	/* clear edit flags */
+	G.f &= ~G_GREASEPENCIL;
+	
+	/* restore cursor to indicate end of drawing */
+	// XXX  (cursor callbacks in regiontype) setcursor_space(p.sa->spacetype, CURSOR_STD);
+	
+	/* check size of buffer before cleanup, to determine if anything happened here */
+	if (p->paintmode == GP_PAINTMODE_ERASER) {
+		// TODO clear radial cursor thing
+		// XXX draw_sel_circle(NULL, p.mvalo, 0, p.radius, 0);
+	}
+	
+	/* cleanup */
+	gp_paint_cleanup(p);
+	gp_session_cleanup(p);
+	
+	/* finally, free the temp data */
+	MEM_freeN(p);
+	op->customdata= NULL;
+}
+
+static int gpencil_draw_cancel (bContext *C, wmOperator *op)
+{
+	/* this is just a wrapper around exit() */
+	gpencil_draw_exit(C, op);
+	return OPERATOR_CANCELLED;
+}
+
+/* ------------------------------- */
+
+static void gpencil_draw_apply_event (bContext *C, wmOperator *op, wmEvent *event)
+{
+	tGPsdata *p= op->customdata;
+	ARegion *ar= p->ar;
+	int tablet=0;
+
+	/* convert from window-space to area-space mouse coordintes */
+	// NOTE: float to ints conversions, +1 factor is probably used to ensure a bit more accurate rounding...
+	p->mval[0]= event->x - ar->winrct.xmin + 1;
+	p->mval[1]= event->y - ar->winrct.ymin + 1;
+	
+	/* handle pressure sensitivity (which is supplied by tablets) */
+	if (event->custom == EVT_DATA_TABLET) {
+		wmTabletData *wmtab= event->customdata;
+		
+		tablet= (wmtab->Active != EVT_TABLET_NONE);
+		p->pressure= wmtab->Pressure;
+		//if (wmtab->Active == EVT_TABLET_ERASER)
+			// TODO... this should get caught by the keymaps which call drawing in the first place
+	}
+	else
+		p->pressure= 1.0f;
+	
+	/* special exception for start of strokes (i.e. maybe for just a dot) */
+	if (p->flags & GP_PAINTFLAG_FIRSTRUN) {
+		p->flags &= ~GP_PAINTFLAG_FIRSTRUN;
+		
+		p->mvalo[0]= p->mval[0];
+		p->mvalo[1]= p->mval[1];
+		p->opressure= p->pressure;
+		
+		/* special exception here for too high pressure values on first touch in
+		 *  windows for some tablets, then we just skip first touch ..  
+		 */
+		if (tablet && (p->pressure >= 0.99f))
+			return;
+	}
+	
+	
+	/* handle drawing/erasing -> test for erasing first */
+	if (p->paintmode == GP_PAINTMODE_ERASER) {
+		/* do 'live' erasing now */
+		gp_stroke_doeraser(p);
+		
+		/* store used values */
+		p->mvalo[0]= p->mval[0];
+		p->mvalo[1]= p->mval[1];
+		p->opressure= p->pressure;
+	}
+	/* only add current point to buffer if mouse moved (even though we got an event, it might be just noise) */
+	else if (gp_stroke_filtermval(p, p->mval, p->mvalo)) {
+		/* try to add point */
+		short ok= gp_stroke_addpoint(p, p->mval, p->pressure);
+		
+		/* handle errors while adding point */
+		if ((ok == GP_STROKEADD_FULL) || (ok == GP_STROKEADD_OVERFLOW)) {
+			/* finish off old stroke */
+			gp_paint_strokeend(p);
+			
+			/* start a new stroke, starting from previous point */
+			gp_stroke_addpoint(p, p->mvalo, p->opressure);
+			ok= gp_stroke_addpoint(p, p->mval, p->pressure);
+		}
+		else if (ok == GP_STROKEADD_INVALID) {
+			/* the painting operation cannot continue... */
+			BKE_report(op->reports, RPT_ERROR, "Cannot paint stroke");
+			p->status = GP_STATUS_ERROR;
+			
+			if (G.f & G_DEBUG) 
+				printf("Error: Grease-Pencil Paint - Add Point Invalid \n");
+			// XXX break!
+		}
+		
+		/* store used values */
+		p->mvalo[0]= p->mval[0];
+		p->mvalo[1]= p->mval[1];
+		p->opressure= p->pressure;
+	}
+	
+	/* force refresh */
+	ED_area_tag_redraw(p->sa); // XXX this is crude
+}
+
+/* ------------------------------- */
+
+static int gpencil_draw_invoke (bContext *C, wmOperator *op, wmEvent *event)
+{
+	tGPsdata *p = NULL;
+	
+	printf("GPencil - Starting Drawing \n");
+	
+	/* try to initialise context data needed while drawing */
+	if (!gpencil_draw_init(C, op)) {
+		if (op->customdata) MEM_freeN(op->customdata);
+		printf("\tGP - no valid data \n");
+		return OPERATOR_CANCELLED;
+	}
+	else
+		p= op->customdata;
+	
+	// TODO: set any additional settings that we can take from the events?
+	// TODO? if tablet is erasing, force eraser to be on?
+	
+	/* if eraser is on, draw radial aid */
+	if (p->paintmode == GP_PAINTMODE_ERASER) {
+		// TODO: this involves mucking around with radial control, so we leave this for now..
+	}
+	
+	printf("\tGP - set first spot\n");
+	
+	/* handle the initial drawing - i.e. for just doing a simple dot */
+	gpencil_draw_apply_event(C, op, event);
+	
+	/* add a modal handler for this operator, so that we can then draw continuous strokes */
+	WM_event_add_modal_handler(C, &CTX_wm_window(C)->handlers, op);
+	return OPERATOR_RUNNING_MODAL;
+}
+
+static int gpencil_draw_modal (bContext *C, wmOperator *op, wmEvent *event)
+{
+	tGPsdata *p= op->customdata;
+	
+	printf("\tGP - handle modal event...\n");
+	
+	switch (event->type) {
+		/* moving mouse - assumed that mouse button is down */
+		case MOUSEMOVE:
+			/* handle drawing event */
+			printf("\t\tGP - add point\n");
+			gpencil_draw_apply_event(C, op, event);
+			
+			/* finish painting operation if anything went wrong just now */
+			if (p->status == GP_STATUS_ERROR) {
+				printf("\t\t\tGP - error done! \n");
+				gpencil_draw_exit(C, op);
+				return OPERATOR_CANCELLED;
+			}
+			break;
+		
+		/* end of stroke - i.e. when a mouse-button release occurs */
+		case LEFTMOUSE:
+		case MIDDLEMOUSE:
+		case RIGHTMOUSE: 
+			printf("\t\tGP - end of stroke \n");
+			gpencil_draw_exit(C, op);
+			return OPERATOR_FINISHED;
+			
+		/* scrolling mouse-wheel increases radius of eraser 
+		 * 	- though this is quite a difficult action to perform
+		 */
+		case WHEELUPMOUSE:
+			p->radius += 1.5f;
+			break;
+		case WHEELDOWNMOUSE:
+			p->radius -= 1.5f;
+			break;
+			
+		/* handle ctrl key - used to toggle straight-lines only (for drawing) */
+		// XXX hardcoded keymap stuff
+		case LEFTCTRLKEY:
+		case RIGHTCTRLKEY:
+			if (event->val == KM_PRESS)
+				p->flags |= GP_PAINTFLAG_STRAIGHTLINES;
+			else if (event->val == KM_RELEASE)
+				p->flags &= ~GP_PAINTFLAG_STRAIGHTLINES;
+			break;
+			
+		default:
+			return OPERATOR_RUNNING_MODAL|OPERATOR_PASS_THROUGH;
+			break;
+	}
+	
+	return OPERATOR_RUNNING_MODAL;
+}
+
+/* ------------------------------- */
+
+static EnumPropertyItem prop_gpencil_drawmodes[] = {
+	{GP_PAINTMODE_DRAW, "DRAW", 0, "Draw", ""},
+	{GP_PAINTMODE_ERASER, "ERASER", 0, "Eraser", ""},
+	{0, NULL, 0, NULL, NULL}
+};
+
+void GPENCIL_OT_draw (wmOperatorType *ot)
+{
+	/* identifiers */
+	ot->name= "Grease Pencil Draw";
+	ot->idname= "GPENCIL_OT_draw";
+	ot->description= "Make annotations on the active data.";
+	
+	/* api callbacks */
+	//ot->exec= gpencil_draw_exec;
+	ot->invoke= gpencil_draw_invoke;
+	ot->modal= gpencil_draw_modal;
+	ot->cancel= gpencil_draw_cancel;
+	ot->poll= gpencil_draw_poll;
+	
+	/* flags */
+	ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO|OPTYPE_BLOCKING;
+	
+	/* settings for drawing */
+	RNA_def_enum(ot->srna, "mode", prop_gpencil_drawmodes, 0, "Mode", "Way to intepret mouse movements.");
+}
diff --git a/source/blender/editors/include/ED_gpencil.h b/source/blender/editors/include/ED_gpencil.h
index ad8124c89d7..c1e37ce2e81 100644
--- a/source/blender/editors/include/ED_gpencil.h
+++ b/source/blender/editors/include/ED_gpencil.h
@@ -41,7 +41,7 @@ struct bGPDframe;
 struct bGPdata;
 struct uiBlock;
 struct ImBuf;
-
+struct wmWindowManager;
 
 
 /* ------------- Grease-Pencil Helpers -------------- */
@@ -52,9 +52,19 @@ typedef struct tGPspoint {
 	float pressure;			/* pressure of tablet at this point */
 } tGPspoint;
 
+/* ----------- Grease Pencil New Tools ------------- */
+
+struct bGPdata *gpencil_data_getactive(struct bContext *C);
+
+/* ----------- Grease Pencil Operators ------------- */
+
+void gpencil_common_keymap(struct wmWindowManager *wm, ListBase *keymap);
+
+void ED_operatortypes_gpencil(void);
+
 /* ------------ Grease-Pencil Depreceated Stuff ------------------ */
 
-struct bGPdata *gpencil_data_getactive(struct ScrArea *sa);
+//struct bGPdata *gpencil_data_getactive(struct ScrArea *sa);
 short gpencil_data_setactive(struct ScrArea *sa, struct bGPdata *gpd);
 struct ScrArea *gpencil_data_findowner(struct bGPdata *gpd);
 
diff --git a/source/blender/editors/space_api/spacetypes.c b/source/blender/editors/space_api/spacetypes.c
index 041e6a09323..61b6fe391ae 100644
--- a/source/blender/editors/space_api/spacetypes.c
+++ b/source/blender/editors/space_api/spacetypes.c
@@ -42,6 +42,7 @@
 #include "ED_anim_api.h"
 #include "ED_armature.h"
 #include "ED_curve.h"
+#include "ED_gpencil.h"
 #include "ED_markers.h"
 #include "ED_mesh.h"
 #include "ED_object.h"
@@ -83,7 +84,7 @@ void ED_spacetypes_init(void)
 	/* register operator types for screen and all spaces */
 	ED_operatortypes_screen();
 	ED_operatortypes_anim();
-	ED_operatortypes_animchannels(); // XXX have this as part of anim() ones instead?
+	ED_operatortypes_animchannels();
 	ED_operatortypes_object();
 	ED_operatortypes_mesh();
 	ED_operatortypes_sculpt();
@@ -97,6 +98,7 @@ void ED_spacetypes_init(void)
 	ED_operatortypes_fluid();
 	ED_operatortypes_metaball();
 	ED_operatortypes_boids();
+	ED_operatortypes_gpencil();
 	
 	ui_view2d_operatortypes();
 	
diff --git a/source/blender/editors/space_view3d/view3d_draw.c b/source/blender/editors/space_view3d/view3d_draw.c
index 905657910b8..07ffb35f807 100644
--- a/source/blender/editors/space_view3d/view3d_draw.c
+++ b/source/blender/editors/space_view3d/view3d_draw.c
@@ -78,6 +78,7 @@
 
 #include "ED_armature.h"
 #include "ED_keyframing.h"
+#include "ED_gpencil.h"
 #include "ED_mesh.h"
 #include "ED_screen.h"
 #include "ED_space_api.h"
@@ -2082,8 +2083,8 @@ void view3d_main_area_draw(const bContext *C, ARegion *ar)
 	}
 	
 	/* draw grease-pencil stuff */
-//	if (v3d->flag2 & V3D_DISPGP)
-//		draw_gpencil_3dview(ar, 1);
+	//if (v3d->flag2 & V3D_DISPGP)
+		draw_gpencil_3dview(C, 1);
 	
 	BDR_drawSketch(C);
 	
diff --git a/source/blender/editors/space_view3d/view3d_ops.c b/source/blender/editors/space_view3d/view3d_ops.c
index e9d1f6406b0..19a70834587 100644
--- a/source/blender/editors/space_view3d/view3d_ops.c
+++ b/source/blender/editors/space_view3d/view3d_ops.c
@@ -52,6 +52,7 @@
 #include "WM_api.h"
 #include "WM_types.h"
 
+#include "ED_gpencil.h"
 #include "ED_screen.h"
 #include "ED_transform.h"
 
@@ -131,7 +132,10 @@ void view3d_keymap(wmWindowManager *wm)
 	WM_keymap_add_item(keymap, "SKETCH_OT_draw_preview", MOUSEMOVE, KM_ANY, 0, 0);
 	km = WM_keymap_add_item(keymap, "SKETCH_OT_draw_preview", MOUSEMOVE, KM_ANY, KM_CTRL, 0);
 	RNA_boolean_set(km->ptr, "snap", 1);
-
+	
+	/* grease pencil */
+	gpencil_common_keymap(wm, keymap); // XXX
+	
 	WM_keymap_verify_item(keymap, "VIEW3D_OT_manipulator", LEFTMOUSE, KM_PRESS, 0, 0); /* manipulator always on left mouse, not on action mouse*/
 	
 	WM_keymap_verify_item(keymap, "VIEW3D_OT_cursor3d", ACTIONMOUSE, KM_PRESS, 0, 0);