Update documentation and implementations of bounding box calculations. Rename functions to fit their behavior

geometric/bounding-box.c

@@ -145,7 +145,7 @@ static void calculate_path_miter_points(struct vector_2d *a, struct vector_2d *b
 	vector_2d_subtract(m2, m2, &v_vec);
 }
 
-void bounding_box_calculate_path_box(GList *vertices, double thickness,
+void bounding_box_update_with_path(GList *vertices, double thickness,
 					conv_generic_to_vector_2d_t conv_func, union bounding_box *box)
 {
 	GList *vertex_iterator;
@@ -191,24 +191,40 @@ void bounding_box_update_point(union bounding_box *destination, conv_generic_to_
 	destination->vectors.upper_right.y = MAX(destination->vectors.upper_right.y, point.y);
 }
 
-/**
- * @brief Apply transformations onto bounding box.
- * @param scale Scaling factor
- * @param rotation_deg Roation of bounding box around the origin in degrees (counterclockwise)
- * @param flip_at_x Flip the boundig box on the x axis before rotating.
- * @param box Bounding box the operations should be applied to.
- */
+void bounding_box_get_all_points(struct vector_2d *points, union bounding_box *box)
+{
+	if (!points || !box)
+		return;
+
+	points[0].x = box->vectors.lower_left.x;
+	points[0].y = box->vectors.lower_left.y;
+	points[1].x = box->vectors.upper_right.x;
+	points[1].y = box->vectors.lower_left.y;
+	points[2].x = box->vectors.upper_right.x;
+	points[2].y = box->vectors.upper_right.y;
+	points[3].x = box->vectors.lower_left.x;
+	points[3].y = box->vectors.upper_right.y;
+}
+
 void bounding_box_apply_transform(double scale, double rotation_deg, bool flip_at_x, union bounding_box *box)
 {
 	int i;
+	struct vector_2d input_points[4];
 
-	/* Due to linearity, the order of the operations does not matter.
-	 * flip must be applied before rotation as defined by the GDS format
-	 */
-	for (i = 0; i < 2; i++) {
-		box->vector_array[i].y *= (flip_at_x ? -1 : 1);
-		vector_2d_rotate(&box->vector_array[i], rotation_deg * M_PI / 180);
-		vector_2d_scale(&box->vector_array[i], scale);
+	if (!box)
+		return;
+
+	bounding_box_get_all_points(input_points, box);
+
+	/* Reset box */
+	bounding_box_prepare_empty(box);
+
+	for (i = 0; i < 4; i++) {
+		input_points[i].y *= (flip_at_x ? -1 : 1);
+		vector_2d_rotate(&input_points[i], rotation_deg * M_PI / 180.0);
+		vector_2d_scale(&input_points[i], scale);
+
+		bounding_box_update_point(box, NULL, &input_points[i]);
 	}
 }
 

geometric/cell-geometrics.c

@@ -63,7 +63,7 @@ static void update_box_with_gfx(union bounding_box *box, struct gds_graphics *gf
 		 * Please be aware if paths are the outmost elements of your cell.
 		 * You might end up with a completely wrong calculated cell size.
 		 */
-		bounding_box_calculate_path_box(gfx->vertices, gfx->width_absolute,
+		bounding_box_update_with_path(gfx->vertices, gfx->width_absolute,
 							(conv_generic_to_vector_2d_t)&convert_gds_point_to_2d_vector,
 							&current_box);
 		break;

include/gds-render/geometric/bounding-box.h

@@ -46,12 +46,75 @@ union bounding_box {
 
 typedef void (*conv_generic_to_vector_2d_t)(void *, struct vector_2d *);
 
+/**
+ * @brief Calculate bounding box of polygon
+ * @param vertices List of vertices that describe the polygon
+ * @param conv_func Conversion function to convert vertices to vector_2d structs.
+ * @param box Box to write to. This box is not updated! All previous data is discarded
+ */
 void bounding_box_calculate_polygon(GList *vertices, conv_generic_to_vector_2d_t conv_func, union bounding_box *box);
+
+/**
+ * @brief Update an exisitng bounding box with another one.
+ * @param destination Target box to update
+ * @param update Box to update the target with
+ */
 void bounding_box_update_box(union bounding_box *destination, union bounding_box *update);
+
+/**
+ * @brief Prepare an empty bounding box.
+ *
+ * Updating this specially prepared box, results in a bounding box that is the same size as the update
+ *
+ * @param box Box to preapre
+ */
 void bounding_box_prepare_empty(union bounding_box *box);
+
+/**
+ * @brief Update bounding box with a point
+ * @param destination Bounding box to update
+ * @param conv_func Conversion function to convert \p pt to a vector_2d. May be NULL
+ * @param pt Point to update bounding box with
+ */
 void bounding_box_update_point(union bounding_box *destination, conv_generic_to_vector_2d_t conv_func, void *pt);
+
+/**
+ * @brief Return all four corner points of a bounding box
+ * @param[out] points Array of 4 vector_2d structs that has to be allocated by the caller
+ * @param box Bounding box
+ */
+void bounding_box_get_all_points(struct vector_2d *points, union bounding_box *box);
+
+/**
+ * @brief Apply transformations onto bounding box.
+ *
+ * All corner points of the bounding \f$ \vec{P_i} \f$ box are transformed to output points \f$ \vec{P_o} \f$ by:
+ *
+ * \f$ \vec{P_o} = s \cdot \begin{pmatrix}\cos\left(\phi\right) & -\sin\left(\phi\right)\\ \sin\left(\phi\right) & \cos\left(\phi\right)\end{pmatrix} \cdot \begin{pmatrix} 1 & 0 \\ 0 & -1^{m} \end{pmatrix} \cdot \vec{P_i} \f$, with:
+ *
+ * * \f$s\f$: Scale
+ * * \f$m\f$: 1, if flipped_at_x is True, else 0
+ * * \f$\phi\f$: Rotation angle in radians. The conversion degrees => radians is done internally
+ *
+ * The result is the bounding box generated around all output points
+ *
+ * @param scale Scaling factor
+ * @param rotation_deg Rotation of bounding box around the origin in degrees (counterclockwise)
+ * @param flip_at_x Flip the boundig box on the x axis before rotating.
+ * @param box Bounding box the operations should be applied to.
+ * @note Keep in mind, that this bounding boxy is actually the bounding box of the rotated boundig box and not the object itself.
+ *       It might be too big.
+ */
 void bounding_box_apply_transform(double scale, double rotation_deg, bool flip_at_x, union bounding_box *box);
-void bounding_box_calculate_path_box(GList *vertices, double thickness, conv_generic_to_vector_2d_t conv_func, union bounding_box *box);
+
+/**
+ * @brief Calculate the bounding box of a path and update the given bounding box
+ * @param vertices Vertices the path is made up of
+ * @param thickness Thisckness of the path
+ * @param conv_func Conversion function for vertices to vector_2d structs
+ * @param box Bounding box to write results in.
+ */
+void bounding_box_update_with_path(GList *vertices, double thickness, conv_generic_to_vector_2d_t conv_func, union bounding_box *box);
 
 #endif /* _BOUNDING_BOX_H_ */