Paint: add BKE_paint_ensure to initialize toolsettings

Each mode had its own logic for initializing paint structs,
move to a single function.

Also remove "BKE_brush_get_gpencil_paint", entering grease pencil
mode is responsible for ensuring the data is created.

source/blender/blenkernel/BKE_brush.h

@@ -62,7 +62,6 @@ void BKE_brush_sculpt_reset(struct Brush *brush);
 void BKE_brush_gpencil_presets(struct bContext *C);
 void BKE_brush_update_material(struct Main *bmain, struct Material *ma, struct Brush *exclude_brush);
 struct Brush *BKE_brush_getactive_gpencil(struct ToolSettings *ts);
-struct Paint *BKE_brush_get_gpencil_paint(struct ToolSettings *ts);
 
 /* image icon function */
 struct ImBuf *get_brush_icon(struct Brush *brush);

source/blender/blenkernel/BKE_paint.h

@@ -61,6 +61,7 @@ struct Tex;
 struct ImagePool;
 struct UnifiedPaintSettings;
 struct Depsgraph;
+struct ToolSettings;
 
 enum eOverlayFlags;
 
@@ -124,6 +125,7 @@ void BKE_paint_curve_copy_data(
 struct PaintCurve *BKE_paint_curve_copy(struct Main *bmain, const struct PaintCurve *pc);
 void               BKE_paint_curve_make_local(struct Main *bmain, struct PaintCurve *pc, const bool lib_local);
 
+bool BKE_paint_ensure(const struct ToolSettings *ts, struct Paint **r_paint);
 void BKE_paint_init(struct Main *bmain, struct Scene *sce, ePaintMode mode, const char col[3]);
 void BKE_paint_free(struct Paint *p);
 void BKE_paint_copy(struct Paint *src, struct Paint *tar, const int flag);

source/blender/blenkernel/intern/brush.c

@@ -193,7 +193,7 @@ void BKE_brush_init_gpencil_settings(Brush *brush)
 Brush *BKE_brush_add_gpencil(Main *bmain, ToolSettings *ts, const char *name)
 {
 	Brush *brush;
-	Paint *paint = BKE_brush_get_gpencil_paint(ts);
+	Paint *paint = &ts->gp_paint->paint;
 	brush = BKE_brush_add(bmain, name, OB_MODE_GPENCIL_PAINT);
 
 	BKE_paint_brush_set(paint, brush);
@@ -208,16 +208,6 @@ Brush *BKE_brush_add_gpencil(Main *bmain, ToolSettings *ts, const char *name)
 	return brush;
 }
 
-Paint *BKE_brush_get_gpencil_paint(ToolSettings *ts)
-{
-	/* alloc paint session */
-	if (ts->gp_paint == NULL) {
-		ts->gp_paint = MEM_callocN(sizeof(GpPaint), "GpPaint");
-	}
-
-	return &ts->gp_paint->paint;
-}
-
 /* grease pencil cumapping->preset */
 typedef enum eGPCurveMappingPreset {
 	GPCURVE_PRESET_PENCIL = 0,
@@ -273,7 +263,7 @@ void BKE_brush_gpencil_presets(bContext *C)
 #define SMOOTH_STROKE_FACTOR 0.9f
 
 	ToolSettings *ts = CTX_data_tool_settings(C);
-	Paint *paint = BKE_brush_get_gpencil_paint(ts);
+	Paint *paint = &ts->gp_paint->paint;
 	Main *bmain = CTX_data_main(C);
 
 	Brush *brush, *deft;

source/blender/blenkernel/intern/paint.c

@@ -570,6 +570,53 @@ eObjectMode BKE_paint_object_mode_from_paint_mode(ePaintMode mode)
 	}
 }
 
+/**
+ * Call when entering each respective paint mode.
+ */
+bool BKE_paint_ensure(const ToolSettings *ts, struct Paint **r_paint)
+{
+	Paint *paint = NULL;
+	if (*r_paint) {
+		/* Note: 'ts->imapaint' is ignored, it's not allocated. */
+		BLI_assert(
+		        ELEM(*r_paint,
+		             &ts->gp_paint->paint,
+		             &ts->sculpt->paint,
+		             &ts->vpaint->paint,
+		             &ts->wpaint->paint,
+		             &ts->uvsculpt->paint));
+		return true;
+	}
+
+	if (ELEM(*r_paint, &ts->vpaint->paint, &ts->wpaint->paint)) {
+		VPaint *data = MEM_callocN(sizeof(*data), __func__);
+		paint = &data->paint;
+	}
+	else if (*r_paint == &ts->sculpt->paint) {
+		Sculpt *data = MEM_callocN(sizeof(*data), __func__);
+		paint = &data->paint;
+
+		/* Turn on X plane mirror symmetry by default */
+		paint->symmetry_flags |= PAINT_SYMM_X;
+
+		/* Make sure at least dyntopo subdivision is enabled */
+		data->flags |= SCULPT_DYNTOPO_SUBDIVIDE | SCULPT_DYNTOPO_COLLAPSE;
+	}
+	else if (*r_paint == &ts->gp_paint->paint) {
+		GpPaint *data = MEM_callocN(sizeof(*data), __func__);
+		paint = &data->paint;
+	}
+	else if (*r_paint == &ts->uvsculpt->paint) {
+		UvSculpt *data = MEM_callocN(sizeof(*data), __func__);
+		paint = &data->paint;
+	}
+
+	paint->flags |= PAINT_SHOW_BRUSH;
+
+	*r_paint = paint;
+	return false;
+}
+
 void BKE_paint_init(Main *bmain, Scene *sce, ePaintMode mode, const char col[3])
 {
 	UnifiedPaintSettings *ups = &sce->toolsettings->unified_paint_settings;
@@ -1144,18 +1191,9 @@ int BKE_sculpt_mask_layers_ensure(Object *ob, MultiresModifierData *mmd)
 
 void BKE_sculpt_toolsettings_data_ensure(struct Scene *scene)
 {
+	BKE_paint_ensure(scene->toolsettings, (Paint **)&scene->toolsettings->sculpt);
+
 	Sculpt *sd = scene->toolsettings->sculpt;
-	if (sd == NULL) {
-		sd = scene->toolsettings->sculpt = MEM_callocN(sizeof(Sculpt), __func__);
-
-		/* Turn on X plane mirror symmetry by default */
-		sd->paint.symmetry_flags |= PAINT_SYMM_X;
-		sd->paint.flags |= PAINT_SHOW_BRUSH;
-
-		/* Make sure at least dyntopo subdivision is enabled */
-		sd->flags |= SCULPT_DYNTOPO_SUBDIVIDE | SCULPT_DYNTOPO_COLLAPSE;
-	}
-
 	if (!sd->detail_size) {
 		sd->detail_size = 12;
 	}

source/blender/blenkernel/intern/scene.c

@@ -688,9 +688,6 @@ void BKE_scene_init(Scene *sce)
 	sce->toolsettings->imapaint.normal_angle = 80;
 	sce->toolsettings->imapaint.seam_bleed = 2;
 
-	/* alloc grease pencil drawing brushes */
-	sce->toolsettings->gp_paint = MEM_callocN(sizeof(GpPaint), "GpPaint");
-
 	/* grease pencil multiframe falloff curve */
 	sce->toolsettings->gp_sculpt.cur_falloff = curvemapping_add(1, 0.0f, 0.0f, 1.0f, 1.0f);
 	CurveMapping *gp_falloff_curve = sce->toolsettings->gp_sculpt.cur_falloff;

source/blender/editors/gpencil/gpencil_data.c

@@ -1561,7 +1561,7 @@ static int gp_brush_select_exec(bContext *C, wmOperator *op)
 
 	const int index = RNA_int_get(op->ptr, "index");
 
-	Paint *paint = BKE_brush_get_gpencil_paint(ts);
+	Paint *paint = &ts->gp_paint->paint;
 	int i = 0;
 	for (Brush *brush = bmain->brush.first; brush; brush = brush->id.next) {
 		if (brush->ob_mode == OB_MODE_GPENCIL_PAINT) {

source/blender/editors/gpencil/gpencil_edit.c

@@ -319,7 +319,8 @@ static int gpencil_paintmode_toggle_exec(bContext *C, wmOperator *op)
 
 	if (mode == OB_MODE_GPENCIL_PAINT) {
 		/* be sure we have brushes */
-		Paint *paint = BKE_brush_get_gpencil_paint(ts);
+		BKE_paint_ensure(ts, (Paint **)&ts->gp_paint);
+		Paint *paint = &ts->gp_paint->paint;
 		/* if not exist, create a new one */
 		if (paint->brush == NULL) {
 			BKE_brush_gpencil_presets(C);

source/blender/editors/gpencil/gpencil_old.c

@@ -105,7 +105,6 @@ static int gpencil_convert_old_files_exec(bContext *C, wmOperator *UNUSED(op))
 {
 	Main *bmain = CTX_data_main(C);
 	Scene *scene = CTX_data_scene(C);
-	ToolSettings *ts = CTX_data_tool_settings(C);
 	ViewLayer *view_layer = CTX_data_view_layer(C);
 
 	/* Convert grease pencil scene datablock to GP object */
@@ -114,13 +113,6 @@ static int gpencil_convert_old_files_exec(bContext *C, wmOperator *UNUSED(op))
 		ob = BKE_object_add_for_data(bmain, view_layer, OB_GPENCIL, "GP_Scene", &scene->gpd->id, false);
 		zero_v3(ob->loc);
 
-		Paint *paint = BKE_brush_get_gpencil_paint(ts);
-		/* if not exist, create a new one */
-		if (paint->brush == NULL) {
-			/* create new brushes */
-			BKE_brush_gpencil_presets(C);
-		}
-
 		/* convert grease pencil palettes (version >= 2.78)  to materials and weights */
 		bGPdata *gpd = scene->gpd;
 		for (const bGPDpalette *palette = gpd->palettes.first; palette; palette = palette->next) {

source/blender/editors/gpencil/gpencil_paint.c

@@ -1641,7 +1641,7 @@ static void gp_session_validatebuffer(tGPsdata *p)
 static Brush *gp_get_default_eraser(Main *bmain, ToolSettings *ts)
 {
 	Brush *brush_dft = NULL;
-	Paint *paint = BKE_brush_get_gpencil_paint(ts);
+	Paint *paint = &ts->gp_paint->paint;
 	Brush *brush_old = paint->brush;
 	for (Brush *brush = bmain->brush.first; brush; brush = brush->id.next) {
 		if ((brush->ob_mode == OB_MODE_GPENCIL_PAINT) &&
@@ -1685,7 +1685,7 @@ static void gp_init_drawing_brush(bContext *C, tGPsdata *p)
 	Scene *scene = CTX_data_scene(C);
 	ToolSettings *ts = CTX_data_tool_settings(C);
 
-	Paint *paint = BKE_brush_get_gpencil_paint(ts);
+	Paint *paint = &ts->gp_paint->paint;
 
 	/* if not exist, create a new one */
 	if (paint->brush == NULL) {

source/blender/editors/gpencil/gpencil_primitive.c

@@ -144,7 +144,7 @@ static void gp_primitive_set_initdata(bContext *C, tGPDprimitive *tgpi)
 	Brush *brush;
 
 	/* if brush doesn't exist, create a new one */
-	Paint *paint = BKE_brush_get_gpencil_paint(ts);
+	Paint *paint = &ts->gp_paint->paint;
 	/* if not exist, create a new one */
 	if (paint->brush == NULL) {
 		/* create new brushes */

source/blender/editors/gpencil/gpencil_utils.c

@@ -1201,7 +1201,8 @@ void ED_gpencil_add_defaults(bContext *C)
 	/* ensure color exist */
 	BKE_gpencil_material_ensure(bmain, ob);
 
-	Paint *paint = BKE_brush_get_gpencil_paint(ts);
+	BKE_paint_ensure(ts, (Paint **)&ts->gp_paint);
+	Paint *paint = &ts->gp_paint->paint;
 	/* if not exist, create a new one */
 	if (paint->brush == NULL) {
 		/* create new brushes */

source/blender/editors/sculpt_paint/sculpt_uv.c

@@ -236,15 +236,12 @@ void ED_space_image_uv_sculpt_update(Main *bmain, wmWindowManager *wm, Scene *sc
 {
 	ToolSettings *settings = scene->toolsettings;
 	if (settings->use_uv_sculpt) {
-		if (!settings->uvsculpt) {
-			settings->uvsculpt = MEM_callocN(sizeof(*settings->uvsculpt), "UV Smooth paint");
+		if (settings->uvsculpt == NULL) {
 			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_ensure(settings, (Paint **)&settings->uvsculpt);
 		BKE_paint_init(bmain, scene, ePaintSculptUV, PAINT_CURSOR_SCULPT);
 
 		settings->uvsculpt->paint.paint_cursor = WM_paint_cursor_activate(