Math Lib: use x-span for fill_poly_v2i_n callback

Instead of running the callback per-pixel,
pass the x-span to the callback.

source/blender/blenkernel/intern/tracking.c

@@ -814,11 +814,14 @@ typedef struct TrackMaskSetPixelData {
 	int mask_height;
 } TrackMaskSetPixelData;
 
-static void track_mask_set_pixel_cb(int x, int y, void *user_data)
+static void track_mask_set_pixel_cb(int x, int x_end, int y, void *user_data)
 {
 	TrackMaskSetPixelData *data = (TrackMaskSetPixelData *)user_data;
-	size_t index = (size_t)y * data->mask_width + x;
-	data->mask[index] = 1.0f;
+	size_t index =     (size_t)y * data->mask_width + x;
+	size_t index_end = (size_t)y * data->mask_width + x_end;
+	do {
+		data->mask[index] = 1.0f;
+	} while (++index != index_end);
 }
 
 static void track_mask_gpencil_layer_rasterize(int frame_width, int frame_height,

source/blender/blenlib/BLI_math_geom.h

@@ -291,7 +291,7 @@ void plot_line_v2v2i(const int p1[2], const int p2[2], bool (*callback)(int, int
 void fill_poly_v2i_n(
         const int xmin, const int ymin, const int xmax, const int ymax,
         const int polyXY[][2], const int polyCorners,
-        void (*callback)(int, int, void *), void *userData);
+        void (*callback)(int x, int x_end, int y, void *), void *userData);
 /****************************** Interpolation ********************************/
 
 /* tri or quad, d can be NULL */

source/blender/blenlib/intern/math_geom.c

@@ -2642,10 +2642,20 @@ void plot_line_v2v2i(const int p1[2], const int p2[2], bool (*callback)(int, int
 	}
 }
 
+/**
+ * \param callback: Takes the x, y coords and x-span (\a x_end is not inclusive),
+ * note that \a x_end will always be greater than \a x, so we can use:
+ *
+ * \code{.c}
+ * do {
+ *     func(x, y);
+ * } while (++x != x_end);
+ * \endcode
+ */
 void fill_poly_v2i_n(
         const int xmin, const int ymin, const int xmax, const int ymax,
         const int verts[][2], const int nr,
-        void (*callback)(int, int, void *), void *userData)
+        void (*callback)(int x, int x_end, int y, void *), void *userData)
 {
 	/* originally by Darel Rex Finley, 2007 */
 
@@ -2686,9 +2696,18 @@ void fill_poly_v2i_n(
 			if (node_x[i + 1] >  xmin) {
 				if (node_x[i    ] < xmin) node_x[i    ] = xmin;
 				if (node_x[i + 1] > xmax) node_x[i + 1] = xmax;
+
+#if 0
+				/* for many x/y calls */
 				for (j = node_x[i]; j < node_x[i + 1]; j++) {
 					callback(j - xmin, pixel_y - ymin, userData);
 				}
+#else
+				/* for single call per x-span */
+				if (node_x[i] < node_x[i + 1]) {
+					callback(node_x[i] - xmin, node_x[i + 1] - xmin, pixel_y - ymin, userData);
+				}
+#endif
 			}
 		}
 	}

source/blender/editors/mesh/editmesh_select.c

@@ -249,10 +249,14 @@ struct LassoMaskData {
 	int width;
 };
 
-static void edbm_mask_lasso_px_cb(int x, int y, void *user_data)
+static void edbm_mask_lasso_px_cb(int x, int x_end, int y, void *user_data)
 {
 	struct LassoMaskData *data = user_data;
-	data->px[(y * data->width) + x] = true;
+	unsigned int *px = &data->px[(y * data->width) + x];
+	do {
+		*px = true;
+		px++;
+	} while (++x != x_end);
 }
 
 

source/blender/editors/sculpt_paint/paint_mask.c

@@ -315,10 +315,14 @@ static bool is_effected_lasso(LassoMaskData *data, float co[3])
 	return BLI_BITMAP_TEST_BOOL(data->px, scr_co_s[1] * data->width + scr_co_s[0]);
 }
 
-static void mask_lasso_px_cb(int x, int y, void *user_data)
+static void mask_lasso_px_cb(int x, int x_end, int y, void *user_data)
 {
 	struct LassoMaskData *data = user_data;
-	BLI_BITMAP_ENABLE(data->px, (y * data->width) + x);
+	int index     = (y * data->width) + x;
+	int index_end = (y * data->width) + x_end;
+	do {
+		BLI_BITMAP_ENABLE(data->px, index);
+	} while (++index != index_end);
 }
 
 static int paint_mask_gesture_lasso_exec(bContext *C, wmOperator *op)

source/blender/windowmanager/intern/wm_gesture.c

@@ -235,12 +235,15 @@ struct LassoFillData {
 	int width;
 };
 
-static void draw_filled_lasso_px_cb(int x, int y, void *user_data)
+static void draw_filled_lasso_px_cb(int x, int x_end, int y, void *user_data)
 {
 	struct LassoFillData *data = user_data;
 	unsigned char *col = (unsigned char *)&(data->px[(y * data->width) + x]);
-	col[0] = col[1] = col[2] = 0xff;
-	col[3] = 0x10;
+	do {
+		col[0] = col[1] = col[2] = 0xff;
+		col[3] = 0x10;
+		col += 4;
+	} while (++x != x_end);
 }
 
 static void draw_filled_lasso(wmWindow *win, wmGesture *gt)