Fix transform crash in rare cases

In some cases transform modes would use the custom-data pointer,
other times the transform conversion functions would.

However with some combinations (bone mirror + bend for eg),
both conversion & transform mode would use this pointer causing a crash.

Fix this by having 2 custom-data pointers:
one for the mode, another for the data-type.

This also simplifies time-slide which was conditionally mixing mode/type data in the one array.

5 files changed, 160 insertions, 151 deletions

diff --git a/source/blender/editors/transform/transform.c b/source/blender/editors/transform/transform.c
index bc60a0c6107..307194ca592 100644
--- a/source/blender/editors/transform/transform.c
+++ b/source/blender/editors/transform/transform.c
@@ -2858,7 +2858,7 @@ static void initBend(TransInfo *t)
 	t->num.unit_type[0] = B_UNIT_ROTATION;
 	t->num.unit_type[1] = B_UNIT_LENGTH;
 
-	t->flag |= T_NO_CONSTRAINT | T_FREE_CUSTOMDATA;
+	t->flag |= T_NO_CONSTRAINT;
 
 	//copy_v3_v3(t->center, ED_view3d_cursor3d_get(t->scene, t->view));
 	calculateCenterCursor(t, t->center);
@@ -2886,7 +2886,8 @@ static void initBend(TransInfo *t)
 
 	data->warp_init_dist = len_v3v3(data->warp_end, data->warp_sta);
 
-	t->customData = data;
+	t->custom.mode.data = data;
+	t->custom.mode.use_free = true;
 }
 
 static eRedrawFlag handleEventBend(TransInfo *UNUSED(t), const wmEvent *event)
@@ -2908,7 +2909,7 @@ static void Bend(TransInfo *t, const int UNUSED(mval[2]))
 	float warp_end_radius[3];
 	int i;
 	char str[MAX_INFO_LEN];
-	const struct BendCustomData *data = t->customData;
+	const struct BendCustomData *data = t->custom.mode.data;
 	const bool is_clamp = (t->flag & T_ALT_TRANSFORM) == 0;
 
 	union {
@@ -3065,27 +3066,27 @@ static eRedrawFlag handleEventShear(TransInfo *t, const wmEvent *event)
 	eRedrawFlag status = TREDRAW_NOTHING;
 	
 	if (event->type == MIDDLEMOUSE && event->val == KM_PRESS) {
-		// Use customData pointer to signal Shear direction
-		if (t->customData == NULL) {
+		/* Use custom.mode.data pointer to signal Shear direction */
+		if (t->custom.mode.data == NULL) {
 			initMouseInputMode(t, &t->mouse, INPUT_VERTICAL_ABSOLUTE);
-			t->customData = (void *)1;
+			t->custom.mode.data = (void *)1;
 		}
 		else {
 			initMouseInputMode(t, &t->mouse, INPUT_HORIZONTAL_ABSOLUTE);
-			t->customData = NULL;
+			t->custom.mode.data = NULL;
 		}
 
 		status = TREDRAW_HARD;
 	}
 	else if (event->type == XKEY && event->val == KM_PRESS) {
 		initMouseInputMode(t, &t->mouse, INPUT_HORIZONTAL_ABSOLUTE);
-		t->customData = NULL;
+		t->custom.mode.data = NULL;
 		
 		status = TREDRAW_HARD;
 	}
 	else if (event->type == YKEY && event->val == KM_PRESS) {
 		initMouseInputMode(t, &t->mouse, INPUT_VERTICAL_ABSOLUTE);
-		t->customData = (void *)1;
+		t->custom.mode.data = (void *)1;
 		
 		status = TREDRAW_HARD;
 	}
@@ -3131,7 +3132,7 @@ static void applyShear(TransInfo *t, const int UNUSED(mval[2]))
 	unit_m3(smat);
 	
 	// Custom data signals shear direction
-	if (t->customData == NULL)
+	if (t->custom.mode.data == NULL)
 		smat[1][0] = value;
 	else
 		smat[0][1] = value;
@@ -5680,7 +5681,7 @@ static void slide_origdata_free_date(
 
 static void calcEdgeSlideCustomPoints(struct TransInfo *t)
 {
-	EdgeSlideData *sld = t->customData;
+	EdgeSlideData *sld = t->custom.mode.data;
 
 	setCustomPoints(t, &t->mouse, sld->mval_end, sld->mval_start);
 
@@ -6425,7 +6426,7 @@ static bool createEdgeSlideVerts_double_side(TransInfo *t, bool use_even, bool f
 	
 	sld->perc = 0.0f;
 	
-	t->customData = sld;
+	t->custom.mode.data = sld;
 	
 	MEM_freeN(sv_table);
 
@@ -6627,7 +6628,7 @@ static bool createEdgeSlideVerts_single_side(TransInfo *t, bool use_even, bool f
 
 	sld->perc = 0.0f;
 
-	t->customData = sld;
+	t->custom.mode.data = sld;
 
 	MEM_freeN(sv_table);
 
@@ -6636,7 +6637,7 @@ static bool createEdgeSlideVerts_single_side(TransInfo *t, bool use_even, bool f
 
 void projectEdgeSlideData(TransInfo *t, bool is_final)
 {
-	EdgeSlideData *sld = t->customData;
+	EdgeSlideData *sld = t->custom.mode.data;
 	SlideOrigData *sod = &sld->orig_data;
 
 	if (sod->use_origfaces == false) {
@@ -6651,9 +6652,9 @@ void freeEdgeSlideTempFaces(EdgeSlideData *sld)
 	slide_origdata_free_date(&sld->orig_data);
 }
 
-void freeEdgeSlideVerts(TransInfo *t)
+void freeEdgeSlideVerts(TransInfo *UNUSED(t), TransCustomData *custom_data)
 {
-	EdgeSlideData *sld = t->customData;
+	EdgeSlideData *sld = custom_data->data;
 	
 	if (!sld)
 		return;
@@ -6665,7 +6666,7 @@ void freeEdgeSlideVerts(TransInfo *t)
 	MEM_freeN(sld->sv);
 	MEM_freeN(sld);
 	
-	t->customData = NULL;
+	custom_data->data = NULL;
 }
 
 static void initEdgeSlide_ex(TransInfo *t, bool use_double_side, bool use_even, bool flipped, bool use_clamp)
@@ -6689,12 +6690,12 @@ static void initEdgeSlide_ex(TransInfo *t, bool use_double_side, bool use_even,
 		return;
 	}
 	
-	sld = t->customData;
+	sld = t->custom.mode.data;
 
 	if (!sld)
 		return;
 
-	t->customFree = freeEdgeSlideVerts;
+	t->custom.mode.free_cb = freeEdgeSlideVerts;
 
 	/* set custom point first if you want value to be initialized by init */
 	calcEdgeSlideCustomPoints(t);
@@ -6721,7 +6722,7 @@ static void initEdgeSlide(TransInfo *t)
 static eRedrawFlag handleEventEdgeSlide(struct TransInfo *t, const struct wmEvent *event)
 {
 	if (t->mode == TFM_EDGE_SLIDE) {
-		EdgeSlideData *sld = t->customData;
+		EdgeSlideData *sld = t->custom.mode.data;
 
 		if (sld) {
 			switch (event->type) {
@@ -6770,8 +6771,8 @@ static eRedrawFlag handleEventEdgeSlide(struct TransInfo *t, const struct wmEven
 
 static void drawEdgeSlide(TransInfo *t)
 {
-	if ((t->mode == TFM_EDGE_SLIDE) && t->customData) {
-		EdgeSlideData *sld = t->customData;
+	if ((t->mode == TFM_EDGE_SLIDE) && t->custom.mode.data) {
+		EdgeSlideData *sld = t->custom.mode.data;
 		const bool is_clamp = !(t->flag & T_ALT_TRANSFORM);
 
 		/* Even mode */
@@ -6886,7 +6887,7 @@ static void drawEdgeSlide(TransInfo *t)
 
 static void doEdgeSlide(TransInfo *t, float perc)
 {
-	EdgeSlideData *sld = t->customData;
+	EdgeSlideData *sld = t->custom.mode.data;
 	TransDataEdgeSlideVert *svlist = sld->sv, *sv;
 	int i;
 
@@ -6959,7 +6960,7 @@ static void applyEdgeSlide(TransInfo *t, const int UNUSED(mval[2]))
 	char str[MAX_INFO_LEN];
 	size_t ofs = 0;
 	float final;
-	EdgeSlideData *sld =  t->customData;
+	EdgeSlideData *sld =  t->custom.mode.data;
 	bool flipped = sld->flipped;
 	bool use_even = sld->use_even;
 	const bool is_clamp = !(t->flag & T_ALT_TRANSFORM);
@@ -7013,7 +7014,7 @@ static void applyEdgeSlide(TransInfo *t, const int UNUSED(mval[2]))
 
 static void calcVertSlideCustomPoints(struct TransInfo *t)
 {
-	VertSlideData *sld = t->customData;
+	VertSlideData *sld = t->custom.mode.data;
 	TransDataVertSlideVert *sv = &sld->sv[sld->curr_sv_index];
 
 	const float *co_orig_3d = sv->co_orig_3d;
@@ -7048,7 +7049,7 @@ static void calcVertSlideCustomPoints(struct TransInfo *t)
  */
 static void calcVertSlideMouseActiveVert(struct TransInfo *t, const int mval[2])
 {
-	VertSlideData *sld = t->customData;
+	VertSlideData *sld = t->custom.mode.data;
 	float mval_fl[2] = {UNPACK2(mval)};
 	TransDataVertSlideVert *sv;
 
@@ -7075,7 +7076,7 @@ static void calcVertSlideMouseActiveVert(struct TransInfo *t, const int mval[2])
  */
 static void calcVertSlideMouseActiveEdges(struct TransInfo *t, const int mval[2])
 {
-	VertSlideData *sld = t->customData;
+	VertSlideData *sld = t->custom.mode.data;
 	float imval_fl[2] = {UNPACK2(t->mouse.imval)};
 	float  mval_fl[2] = {UNPACK2(mval)};
 
@@ -7209,7 +7210,7 @@ static bool createVertSlideVerts(TransInfo *t, bool use_even, bool flipped, bool
 
 	sld->perc = 0.0f;
 
-	t->customData = sld;
+	t->custom.mode.data = sld;
 
 	/* most likely will be set below */
 	unit_m4(sld->proj_mat);
@@ -7233,7 +7234,7 @@ static bool createVertSlideVerts(TransInfo *t, bool use_even, bool flipped, bool
 
 void projectVertSlideData(TransInfo *t, bool is_final)
 {
-	VertSlideData *sld = t->customData;
+	VertSlideData *sld = t->custom.mode.data;
 	SlideOrigData *sod = &sld->orig_data;
 
 	if (sod->use_origfaces == false) {
@@ -7248,9 +7249,9 @@ void freeVertSlideTempFaces(VertSlideData *sld)
 	slide_origdata_free_date(&sld->orig_data);
 }
 
-void freeVertSlideVerts(TransInfo *t)
+void freeVertSlideVerts(TransInfo *UNUSED(t), TransCustomData *custom_data)
 {
-	VertSlideData *sld = t->customData;
+	VertSlideData *sld = custom_data->data;
 
 	if (!sld)
 		return;
@@ -7270,7 +7271,7 @@ void freeVertSlideVerts(TransInfo *t)
 	MEM_freeN(sld->sv);
 	MEM_freeN(sld);
 
-	t->customData = NULL;
+	custom_data->data = NULL;
 }
 
 static void initVertSlide_ex(TransInfo *t, bool use_even, bool flipped, bool use_clamp)
@@ -7286,12 +7287,12 @@ static void initVertSlide_ex(TransInfo *t, bool use_even, bool flipped, bool use
 		return;
 	}
 
-	sld = t->customData;
+	sld = t->custom.mode.data;
 
 	if (!sld)
 		return;
 
-	t->customFree = freeVertSlideVerts;
+	t->custom.mode.free_cb = freeVertSlideVerts;
 
 	/* set custom point first if you want value to be initialized by init */
 	calcVertSlideCustomPoints(t);
@@ -7318,7 +7319,7 @@ static void initVertSlide(TransInfo *t)
 static eRedrawFlag handleEventVertSlide(struct TransInfo *t, const struct wmEvent *event)
 {
 	if (t->mode == TFM_VERT_SLIDE) {
-		VertSlideData *sld = t->customData;
+		VertSlideData *sld = t->custom.mode.data;
 
 		if (sld) {
 			switch (event->type) {
@@ -7378,8 +7379,8 @@ static eRedrawFlag handleEventVertSlide(struct TransInfo *t, const struct wmEven
 
 static void drawVertSlide(TransInfo *t)
 {
-	if ((t->mode == TFM_VERT_SLIDE) && t->customData) {
-		VertSlideData *sld = t->customData;
+	if ((t->mode == TFM_VERT_SLIDE) && t->custom.mode.data) {
+		VertSlideData *sld = t->custom.mode.data;
 		const bool is_clamp = !(t->flag & T_ALT_TRANSFORM);
 
 		/* Non-Prop mode */
@@ -7483,7 +7484,7 @@ static void drawVertSlide(TransInfo *t)
 
 static void doVertSlide(TransInfo *t, float perc)
 {
-	VertSlideData *sld = t->customData;
+	VertSlideData *sld = t->custom.mode.data;
 	TransDataVertSlideVert *svlist = sld->sv, *sv;
 	int i;
 
@@ -7527,7 +7528,7 @@ static void applyVertSlide(TransInfo *t, const int UNUSED(mval[2]))
 	char str[MAX_INFO_LEN];
 	size_t ofs = 0;
 	float final;
-	VertSlideData *sld =  t->customData;
+	VertSlideData *sld =  t->custom.mode.data;
 	const bool flipped = sld->flipped;
 	const bool use_even = sld->use_even;
 	const bool is_clamp = !(t->flag & T_ALT_TRANSFORM);
@@ -8277,10 +8278,34 @@ static void initTimeSlide(TransInfo *t)
 
 	t->mode = TFM_TIME_SLIDE;
 	t->transform = applyTimeSlide;
-	t->flag |= T_FREE_CUSTOMDATA;
 
 	initMouseInputMode(t, &t->mouse, INPUT_NONE);
 
+	{
+		Scene *scene = t->scene;
+		float *range;
+		t->custom.mode.data = range = MEM_mallocN(sizeof(float[2]), "TimeSlide Min/Max");
+		t->custom.mode.use_free = true;
+
+		float min = 999999999.0f, max = -999999999.0f;
+		int i;
+
+		TransData  *td = t->data;
+		for (i = 0; i < t->total; i++, td++) {
+			if (min > *(td->val)) min = *(td->val);
+			if (max < *(td->val)) max = *(td->val);
+		}
+
+		if (min == max) {
+			/* just use the current frame ranges */
+			min = (float)PSFRA;
+			max = (float)PEFRA;
+		}
+
+		range[0] = min;
+		range[1] = max;
+	}
+
 	/* num-input has max of (n-1) */
 	t->idx_max = 0;
 	t->num.flag = 0;
@@ -8304,8 +8329,9 @@ static void headerTimeSlide(TransInfo *t, const float sval, char str[MAX_INFO_LE
 		outputNumInput(&(t->num), tvec, &t->scene->unit);
 	}
 	else {
-		float minx = *((float *)(t->customData));
-		float maxx = *((float *)(t->customData) + 1);
+		const float *range = t->custom.mode.data;
+		float minx = range[0];
+		float maxx = range[1];
 		float cval = t->values[0];
 		float val;
 
@@ -8322,9 +8348,9 @@ static void applyTimeSlideValue(TransInfo *t, float sval)
 {
 	TransData *td = t->data;
 	int i;
-
-	float minx = *((float *)(t->customData));
-	float maxx = *((float *)(t->customData) + 1);
+	const float *range = t->custom.mode.data;
+	float minx = range[0];
+	float maxx = range[1];
 
 	/* set value for drawing black line */
 	if (t->spacetype == SPACE_ACTION) {
@@ -8369,8 +8395,9 @@ static void applyTimeSlide(TransInfo *t, const int mval[2])
 {
 	View2D *v2d = (View2D *)t->view;
 	float cval[2], sval[2];
-	float minx = *((float *)(t->customData));
-	float maxx = *((float *)(t->customData) + 1);
+	const float *range = t->custom.mode.data;
+	float minx = range[0];
+	float maxx = range[1];
 	char str[MAX_INFO_LEN];
 
 	/* calculate mouse co-ordinates */
diff --git a/source/blender/editors/transform/transform.h b/source/blender/editors/transform/transform.h
index f6b4d7da57f..c6d801f7160 100644
--- a/source/blender/editors/transform/transform.h
+++ b/source/blender/editors/transform/transform.h
@@ -357,6 +357,12 @@ typedef struct MouseInput {
 	} virtual_mval;
 } MouseInput;
 
+typedef struct TransCustomData {
+	void       *data;
+	void      (*free_cb)(struct TransInfo *, struct TransCustomData *);
+	unsigned int use_free : 1;
+} TransCustomData;
+
 typedef struct TransInfo {
 	int         mode;           /* current mode                         */
 	int	        flag;           /* generic flags for special behaviors  */
@@ -408,8 +414,22 @@ typedef struct TransInfo {
 
 	struct Object *poseobj;		/* if t->flag & T_POSE, this denotes pose object */
 
-	void       *customData;		/* Per Transform custom data */
-	void  	  (*customFree)(struct TransInfo *); /* if a special free function is needed */
+	/**
+	 * Rule of thumb for choosing between mode/type:
+	 * - If transform mode uses the data, assign to `mode`
+	 *   (typically in transform.c).
+	 * - If conversion uses the data as an extension to the #TransData, assign to `type`
+	 *   (typically in transform_conversion.c).
+	 */
+	struct {
+		/* owned by the mode (grab, scale, bend... )*/
+		union {
+			TransCustomData mode, first_elem;
+		};
+		/* owned by the type (mesh, armature, nla...) */
+		TransCustomData type;
+	} custom;
+#define TRANS_CUSTOM_DATA_ELEM_MAX (sizeof(((TransInfo *)NULL)->custom) / sizeof(TransCustomData))
 
 	/*************** NEW STUFF *********************/
 	short		launch_event; 	/* event type used to launch transform */
@@ -484,7 +504,6 @@ typedef struct TransInfo {
 #define T_2D_EDIT			(1 << 15)
 #define T_CLIP_UV			(1 << 16)
 
-#define T_FREE_CUSTOMDATA	(1 << 17)
 	/* auto-ik is on */
 #define T_AUTOIK			(1 << 18)
 
@@ -758,11 +777,11 @@ int getTransformOrientation_ex(const struct bContext *C, float normal[3], float
 int getTransformOrientation(const struct bContext *C, float normal[3], float plane[3]);
 
 void freeEdgeSlideTempFaces(EdgeSlideData *sld);
-void freeEdgeSlideVerts(TransInfo *t);
+void freeEdgeSlideVerts(TransInfo *t, TransCustomData *custom_data);
 void projectEdgeSlideData(TransInfo *t, bool is_final);
 
 void freeVertSlideTempFaces(VertSlideData *sld);
-void freeVertSlideVerts(TransInfo *t);
+void freeVertSlideVerts(TransInfo *t, TransCustomData *custom_data);
 void projectVertSlideData(TransInfo *t, bool is_final);
 
 
diff --git a/source/blender/editors/transform/transform_conversions.c b/source/blender/editors/transform/transform_conversions.c
index 4514171c991..df0edae9a56 100644
--- a/source/blender/editors/transform/transform_conversions.c
+++ b/source/blender/editors/transform/transform_conversions.c
@@ -1088,7 +1088,7 @@ static void createTransPose(TransInfo *t, Object *ob)
 void restoreBones(TransInfo *t)
 {
 	bArmature *arm = t->obedit->data;
-	BoneInitData *bid = t->customData;
+	BoneInitData *bid = t->custom.type.data;
 	EditBone *ebo;
 
 	while (bid->bone) {
@@ -1177,8 +1177,8 @@ static void createTransArmatureVerts(TransInfo *t)
 	td = t->data = MEM_callocN(t->total * sizeof(TransData), "TransEditBone");
 
 	if (mirror) {
-		t->customData = bid = MEM_mallocN((total_mirrored + 1) * sizeof(BoneInitData), "BoneInitData");
-		t->flag |= T_FREE_CUSTOMDATA;
+		t->custom.type.data = bid = MEM_mallocN((total_mirrored + 1) * sizeof(BoneInitData), "BoneInitData");
+		t->custom.type.use_free = true;
 	}
 
 	i = 0;
@@ -3087,9 +3087,8 @@ static void createTransNlaData(bContext *C, TransInfo *t)
 	
 	t->data = MEM_callocN(t->total * sizeof(TransData), "TransData(NLA Editor)");
 	td = t->data;
-	t->customData = MEM_callocN(t->total * sizeof(TransDataNla), "TransDataNla (NLA Editor)");
-	tdn = t->customData;
-	t->flag |= T_FREE_CUSTOMDATA;
+	t->custom.type.data = tdn = MEM_callocN(t->total * sizeof(TransDataNla), "TransDataNla (NLA Editor)");
+	t->custom.type.use_free = true;
 	
 	/* loop 2: build transdata array */
 	for (ale = anim_data.first; ale; ale = ale->next) {
@@ -3550,15 +3549,9 @@ typedef struct tGPFtransdata {
 /* This function helps flush transdata written to tempdata into the gp-frames  */
 void flushTransIntFrameActionData(TransInfo *t)
 {
-	tGPFtransdata *tfd;
+	tGPFtransdata *tfd = t->custom.type.data;
 	int i;
 
-	/* find the first one to start from */
-	if (t->mode == TFM_TIME_SLIDE)
-		tfd = (tGPFtransdata *)((float *)(t->customData) + 2);
-	else
-		tfd = (tGPFtransdata *)(t->customData);
-
 	/* flush data! */
 	for (i = 0; i < t->total; i++, tfd++) {
 		*(tfd->sdata) = iroundf(tfd->val);
@@ -3726,20 +3719,8 @@ static void createTransActionData(bContext *C, TransInfo *t)
 	td2d = t->data2d;
 	
 	if (ELEM(ac.datatype, ANIMCONT_GPENCIL, ANIMCONT_MASK)) {
-		if (t->mode == TFM_TIME_SLIDE) {
-			t->customData = MEM_callocN((sizeof(float) * 2) + (sizeof(tGPFtransdata) * count), "TimeSlide + tGPFtransdata");
-			t->flag |= T_FREE_CUSTOMDATA;
-			tfd = (tGPFtransdata *)((float *)(t->customData) + 2);
-		}
-		else {
-			t->customData = MEM_callocN(sizeof(tGPFtransdata) * count, "tGPFtransdata");
-			t->flag |= T_FREE_CUSTOMDATA;
-			tfd = (tGPFtransdata *)(t->customData);
-		}
-	}
-	else if (t->mode == TFM_TIME_SLIDE) {
-		t->customData = MEM_callocN(sizeof(float) * 2, "TimeSlide Min/Max");
-		t->flag |= T_FREE_CUSTOMDATA;
+		t->custom.type.data = tfd = MEM_callocN(sizeof(tGPFtransdata) * count, "tGPFtransdata");
+		t->custom.type.use_free = true;
 	}
 	
 	/* loop 2: build transdata array */
@@ -3781,31 +3762,6 @@ static void createTransActionData(bContext *C, TransInfo *t)
 			td = ActionFCurveToTransData(td, &td2d, fcu, adt, t->frame_side, cfra, is_prop_edit, ypos);
 		}
 	}
-	
-	/* check if we're supposed to be setting minx/maxx for TimeSlide */
-	if (t->mode == TFM_TIME_SLIDE) {
-		float min = 999999999.0f, max = -999999999.0f;
-		int i;
-		
-		td = t->data;
-		for (i = 0; i < count; i++, td++) {
-			if (min > *(td->val)) min = *(td->val);
-			if (max < *(td->val)) max = *(td->val);
-		}
-		
-		if (min == max) {
-			/* just use the current frame ranges */
-			min = (float)PSFRA;
-			max = (float)PEFRA;
-		}
-		
-		/* minx/maxx values used by TimeSlide are stored as a
-		 * calloced 2-float array in t->customData. This gets freed
-		 * in postTrans (T_FREE_CUSTOMDATA).
-		 */
-		*((float *)(t->customData)) = min;
-		*((float *)(t->customData) + 1) = max;
-	}
 
 	/* calculate distances for proportional editing */
 	if (is_prop_edit) {
@@ -4158,12 +4114,12 @@ static void createTransGraphEditData(bContext *C, TransInfo *t)
 	t->data = MEM_callocN(t->total * sizeof(TransData), "TransData (Graph Editor)");
 	/* for each 2d vert a 3d vector is allocated, so that they can be treated just as if they were 3d verts */
 	t->data2d = MEM_callocN(t->total * sizeof(TransData2D), "TransData2D (Graph Editor)");
-	t->customData = MEM_callocN(t->total * sizeof(TransDataGraph), "TransDataGraph");
-	t->flag |= T_FREE_CUSTOMDATA;
+	t->custom.type.data = MEM_callocN(t->total * sizeof(TransDataGraph), "TransDataGraph");
+	t->custom.type.use_free = true;
 	
 	td = t->data;
 	td2d = t->data2d;
-	tdg = t->customData;
+	tdg = t->custom.type.data;
 	
 	/* precompute space-conversion matrices for dealing with non-uniform scaling of Graph Editor */
 	unit_m3(mtx);
@@ -4565,7 +4521,7 @@ void flushTransGraphData(TransInfo *t)
 	int a;
 
 	/* flush to 2d vector from internally used 3d vector */
-	for (a = 0, td = t->data, td2d = t->data2d, tdg = t->customData;
+	for (a = 0, td = t->data, td2d = t->data2d, tdg = t->custom.type.data;
 	     a < t->total;
 	     a++, td++, td2d++, tdg++)
 	{
@@ -4928,7 +4884,7 @@ static void SeqTransDataBounds(TransInfo *t, ListBase *seqbase, TransSeq *ts)
 }
 
 
-static void freeSeqData(TransInfo *t)
+static void freeSeqData(TransInfo *t, TransCustomData *custom_data)
 {
 	Editing *ed = BKE_sequencer_editing_get(t->scene, false);
 
@@ -5089,11 +5045,11 @@ static void freeSeqData(TransInfo *t)
 		}
 	}
 
-	if ((t->customData != NULL) && (t->flag & T_FREE_CUSTOMDATA)) {
-		TransSeq *ts = t->customData;
+	if ((custom_data->data != NULL) && custom_data->use_free) {
+		TransSeq *ts = custom_data->data;
 		MEM_freeN(ts->tdseq);
-		MEM_freeN(t->customData);
-		t->customData = NULL;
+		MEM_freeN(custom_data->data);
+		custom_data->data = NULL;
 	}
 	if (t->data) {
 		MEM_freeN(t->data); // XXX postTrans usually does this
@@ -5121,7 +5077,7 @@ static void createTransSeqData(bContext *C, TransInfo *t)
 		return;
 	}
 
-	t->customFree = freeSeqData;
+	t->custom.type.free_cb = freeSeqData;
 
 	xmouse = (int)UI_view2d_region_to_view_x(v2d, t->mouse.imval[0]);
 
@@ -5167,11 +5123,11 @@ static void createTransSeqData(bContext *C, TransInfo *t)
 		return;
 	}
 
-	t->customData = ts = MEM_mallocN(sizeof(TransSeq), "transseq");
+	t->custom.type.data = ts = MEM_mallocN(sizeof(TransSeq), "transseq");
+	t->custom.type.use_free = true;
 	td = t->data = MEM_callocN(t->total * sizeof(TransData), "TransSeq TransData");
 	td2d = t->data2d = MEM_callocN(t->total * sizeof(TransData2D), "TransSeq TransData2D");
 	ts->tdseq = tdsq = MEM_callocN(t->total * sizeof(TransDataSeq), "TransSeq TransDataSeq");
-	t->flag |= T_FREE_CUSTOMDATA;
 
 	/* loop 2: build transdata array */
 	SeqToTransData_Recursive(t, ed->seqbasep, td, td2d, tdsq);
@@ -5956,10 +5912,13 @@ void special_aftertrans_update(bContext *C, TransInfo *t)
 	
 	if (t->spacetype == SPACE_VIEW3D) {
 		if (t->obedit) {
+			/* Special Exception:
+			 * We don't normally access 't->custom.mode' here, but its needed in this case. */
+
 			if (canceled == 0) {
 				/* we need to delete the temporary faces before automerging */
 				if (t->mode == TFM_EDGE_SLIDE) {
-					EdgeSlideData *sld = t->customData;
+					EdgeSlideData *sld = t->custom.mode.data;
 
 					/* handle multires re-projection, done
 					 * on transform completion since it's
@@ -5972,7 +5931,7 @@ void special_aftertrans_update(bContext *C, TransInfo *t)
 				}
 				else if (t->mode == TFM_VERT_SLIDE) {
 					/* as above */
-					VertSlideData *sld = t->customData;
+					VertSlideData *sld = t->custom.mode.data;
 					projectVertSlideData(t, true);
 					freeVertSlideTempFaces(sld);
 				}
@@ -5983,13 +5942,13 @@ void special_aftertrans_update(bContext *C, TransInfo *t)
 			}
 			else {
 				if (t->mode == TFM_EDGE_SLIDE) {
-					EdgeSlideData *sld = t->customData;
+					EdgeSlideData *sld = t->custom.mode.data;
 
 					sld->perc = 0.0;
 					projectEdgeSlideData(t, false);
 				}
 				else if (t->mode == TFM_VERT_SLIDE) {
-					VertSlideData *sld = t->customData;
+					VertSlideData *sld = t->custom.mode.data;
 
 					sld->perc = 0.0;
 					projectVertSlideData(t, false);
@@ -6749,16 +6708,15 @@ static void planeTrackToTransData(const int framenr, TransData *td, TransData2D
 	}
 }
 
-static void transDataTrackingFree(TransInfo *t)
+static void transDataTrackingFree(TransInfo *UNUSED(t), TransCustomData *custom_data)
 {
-	TransDataTracking *tdt = t->customData;
-
-	if (tdt) {
+	if (custom_data->data) {
+		TransDataTracking *tdt = custom_data->data;
 		if (tdt->smarkers)
 			MEM_freeN(tdt->smarkers);
 
 		MEM_freeN(tdt);
-		t->customData = NULL;
+		custom_data->data = NULL;
 	}
 }
 
@@ -6810,9 +6768,9 @@ static void createTransTrackingTracksData(bContext *C, TransInfo *t)
 
 	td = t->data = MEM_callocN(t->total * sizeof(TransData), "TransTracking TransData");
 	td2d = t->data2d = MEM_callocN(t->total * sizeof(TransData2D), "TransTracking TransData2D");
-	tdt = t->customData = MEM_callocN(t->total * sizeof(TransDataTracking), "TransTracking TransDataTracking");
+	tdt = t->custom.type.data = MEM_callocN(t->total * sizeof(TransDataTracking), "TransTracking TransDataTracking");
 
-	t->customFree = transDataTrackingFree;
+	t->custom.type.free_cb = transDataTrackingFree;
 
 	/* create actual data */
 	track = tracksbase->first;
@@ -6947,9 +6905,8 @@ static void createTransTrackingCurvesData(bContext *C, TransInfo *t)
 
 	td = t->data = MEM_callocN(t->total * sizeof(TransData), "TransTracking TransData");
 	td2d = t->data2d = MEM_callocN(t->total * sizeof(TransData2D), "TransTracking TransData2D");
-	tdt = t->customData = MEM_callocN(t->total * sizeof(TransDataTracking), "TransTracking TransDataTracking");
-
-	t->customFree = transDataTrackingFree;
+	t->custom.type.data = tdt = MEM_callocN(t->total * sizeof(TransDataTracking), "TransTracking TransDataTracking");
+	t->custom.type.free_cb = transDataTrackingFree;
 
 	/* create actual data */
 	track = tracksbase->first;
@@ -7013,10 +6970,11 @@ static void cancelTransTracking(TransInfo *t)
 {
 	SpaceClip *sc = t->sa->spacedata.first;
 	int i, framenr = ED_space_clip_get_clip_frame_number(sc);
+	TransDataTracking *tdt_array = t->custom.type.data;
 
 	i = 0;
 	while (i < t->total) {
-		TransDataTracking *tdt = (TransDataTracking *) t->customData + i;
+		TransDataTracking *tdt = &tdt_array[i];
 
 		if (tdt->mode == transDataTracking_ModeTracks) {
 			MovieTrackingTrack *track = tdt->track;
@@ -7073,7 +7031,7 @@ void flushTransTracking(TransInfo *t)
 		cancelTransTracking(t);
 
 	/* flush to 2d vector from internally used 3d vector */
-	for (a = 0, td = t->data, td2d = t->data2d, tdt = t->customData; a < t->total; a++, td2d++, td++, tdt++) {
+	for (a = 0, td = t->data, td2d = t->data2d, tdt = t->custom.type.data; a < t->total; a++, td2d++, td++, tdt++) {
 		if (tdt->mode == transDataTracking_ModeTracks) {
 			float loc2d[2];
 
@@ -7404,9 +7362,8 @@ static void createTransMaskingData(bContext *C, TransInfo *t)
 	/* for each 2d uv coord a 3d vector is allocated, so that they can be
 	 * treated just as if they were 3d verts */
 	td2d = t->data2d = MEM_callocN(t->total * sizeof(TransData2D), "TransObData2D(Mask Editing)");
-	tdm = t->customData = MEM_callocN(t->total * sizeof(TransDataMasking), "TransDataMasking(Mask Editing)");
-
-	t->flag |= T_FREE_CUSTOMDATA;
+	t->custom.type.data = tdm = MEM_callocN(t->total * sizeof(TransDataMasking), "TransDataMasking(Mask Editing)");
+	t->custom.type.use_free = true;
 
 	/* create data */
 	for (masklay = mask->masklayers.first; masklay; masklay = masklay->next) {
@@ -7468,7 +7425,7 @@ void flushTransMasking(TransInfo *t)
 	inv[1] = 1.0f / asp[1];
 
 	/* flush to 2d vector from internally used 3d vector */
-	for (a = 0, td = t->data2d, tdm = t->customData; a < t->total; a++, td++, tdm++) {
+	for (a = 0, td = t->data2d, tdm = t->custom.type.data; a < t->total; a++, td++, tdm++) {
 		td->loc2d[0] = td->loc[0] * inv[0];
 		td->loc2d[1] = td->loc[1] * inv[1];
 		mul_m3_v2(tdm->parent_inverse_matrix, td->loc2d);
@@ -7616,8 +7573,8 @@ static void createTransPaintCurveVerts(bContext *C, TransInfo *t)
 	t->total = total;
 	td2d = t->data2d = MEM_callocN(t->total * sizeof(TransData2D), "TransData2D");
 	td = t->data = MEM_callocN(t->total * sizeof(TransData), "TransData");
-	tdpc = t->customData = MEM_callocN(t->total * sizeof(TransDataPaintCurve), "TransDataPaintCurve");
-	t->flag |= T_FREE_CUSTOMDATA;
+	t->custom.type.data = tdpc = MEM_callocN(t->total * sizeof(TransDataPaintCurve), "TransDataPaintCurve");
+	t->custom.type.use_free = true;
 
 	for (pcp = pc->points, i = 0; i < pc->tot_points; i++, pcp++) {
 		if (PC_IS_ANY_SEL(pcp)) {
@@ -7649,7 +7606,7 @@ void flushTransPaintCurve(TransInfo *t)
 {
 	int i;
 	TransData2D *td2d = t->data2d;
-	TransDataPaintCurve *tdpc = (TransDataPaintCurve *)t->customData;
+	TransDataPaintCurve *tdpc = t->custom.type.data;
 
 	for (i = 0; i < t->total; i++, tdpc++, td2d++) {
 		PaintCurvePoint *pcp = tdpc->pcp;
diff --git a/source/blender/editors/transform/transform_generics.c b/source/blender/editors/transform/transform_generics.c
index d43ec0994cb..8d1db148ce5 100644
--- a/source/blender/editors/transform/transform_generics.c
+++ b/source/blender/editors/transform/transform_generics.c
@@ -422,7 +422,7 @@ static void recalcData_graphedit(TransInfo *t)
 /* helper for recalcData() - for NLA Editor transforms */
 static void recalcData_nla(TransInfo *t)
 {
-	TransDataNla *tdn = (TransDataNla *)t->customData;
+	TransDataNla *tdn = t->custom.type.data;
 	SpaceNla *snla = (SpaceNla *)t->sa->spacedata.first;
 	Scene *scene = t->scene;
 	double secf = FPS;
@@ -1055,10 +1055,10 @@ void drawLine(TransInfo *t, const float center[3], const float dir[3], char axis
 void resetTransModal(TransInfo *t)
 {
 	if (t->mode == TFM_EDGE_SLIDE) {
-		freeEdgeSlideVerts(t);
+		freeEdgeSlideVerts(t, &t->custom.mode);
 	}
 	else if (t->mode == TFM_VERT_SLIDE) {
-		freeVertSlideVerts(t);
+		freeVertSlideVerts(t, &t->custom.mode);
 	}
 }
 
@@ -1441,14 +1441,20 @@ void postTrans(bContext *C, TransInfo *t)
 	if (t->draw_handle_cursor)
 		WM_paint_cursor_end(CTX_wm_manager(C), t->draw_handle_cursor);
 
-	if (t->customFree) {
-		/* Can take over freeing t->data and data2d etc... */
-		t->customFree(t);
-		BLI_assert(t->customData == NULL);
-	}
-	else if ((t->customData != NULL) && (t->flag & T_FREE_CUSTOMDATA)) {
-		MEM_freeN(t->customData);
-		t->customData = NULL;
+	/* Free all custom-data */
+	{
+		TransCustomData *custom_data = &t->custom.first_elem;
+		for (int i = 0; i < TRANS_CUSTOM_DATA_ELEM_MAX; i++, custom_data++) {
+			if (custom_data->free_cb) {
+				/* Can take over freeing t->data and data2d etc... */
+				custom_data->free_cb(t, custom_data);
+				BLI_assert(custom_data->data == NULL);
+			}
+			else if ((custom_data->data != NULL) && custom_data->use_free) {
+				MEM_freeN(custom_data->data);
+				custom_data->data = NULL;
+			}
+		}
 	}
 
 	/* postTrans can be called when nothing is selected, so data is NULL already */
diff --git a/source/blender/editors/transform/transform_snap.c b/source/blender/editors/transform/transform_snap.c
index 8e02a402bf8..eb3b08ef5ef 100644
--- a/source/blender/editors/transform/transform_snap.c
+++ b/source/blender/editors/transform/transform_snap.c
@@ -2528,7 +2528,7 @@ void snapSequenceBounds(TransInfo *t, const int mval[2])
 	float xmouse, ymouse;
 	int frame;
 	int mframe;
-	TransSeq *ts = t->customData;
+	TransSeq *ts = t->custom.type.data;
 	/* reuse increment, strictly speaking could be another snap mode, but leave as is */
 	if (!(t->modifiers & MOD_SNAP_INVERT))
 		return;