[lasem] <svg:marker> Automatic orientation computation.

[Emmanuel Pacaud <emmanuel src gnome org>]

commit 63957f66cbac787efe9b41ff75658e22e288e9f4
Author: Emmanuel Pacaud <emmanuel pacaud lapp in2p3 fr>
Date:   Tue Aug 18 10:39:08 2009 +0200

    <svg:marker> Automatic orientation computation.
    
    Thanks to librsvg code.

 src/lsmsvgmarkerelement.c |   11 +++-
 src/lsmsvgview.c          |  136 +++++++++++++++++++++++++++++---------------
 2 files changed, 98 insertions(+), 49 deletions(-)
---
diff --git a/src/lsmsvgmarkerelement.c b/src/lsmsvgmarkerelement.c
index 5c13b02..829fc18 100644
--- a/src/lsmsvgmarkerelement.c
+++ b/src/lsmsvgmarkerelement.c
@@ -88,8 +88,14 @@ _marker_element_render (LsmSvgElement *self, LsmSvgView *view)
 	lsm_debug ("[LsmSvgMarkerElement::render] stroke_width scale = %g",
 		   marker->stroke_width);
 
-	lsm_svg_matrix_init_translate (&matrix, -ref_x, -ref_y);
-	lsm_svg_matrix_rotate (&matrix, marker->vertex_angle);
+	if (marker->orientation.value.type == LSM_SVG_ANGLE_TYPE_FIXED) {
+		lsm_svg_matrix_init_rotate (&matrix, marker->orientation.value.angle);
+		lsm_debug ("[LsmSvgMarkerElement::render] fixed angle = %g", marker->orientation.value.angle);
+	} else {
+		lsm_svg_matrix_init_rotate (&matrix, marker->vertex_angle);
+		lsm_debug ("[LsmSvgMarkerElement::render] auto angle = %g", marker->vertex_angle);
+	}
+	lsm_svg_matrix_translate (&matrix, -ref_x, -ref_y);
 	lsm_svg_view_push_matrix (view, &matrix);
 
 	lsm_svg_view_push_viewport (view, &viewport, &marker->viewbox.value,
@@ -151,6 +157,7 @@ lsm_svg_marker_element_init (LsmSvgMarkerElement *self)
 	self->width.length = width_default;
 	self->height.length = width_default;
 	self->preserve_aspect_ratio.value = preserve_aspect_ratio_default;
+	self->orientation.value = orientation_default;
 }
 
 static void
diff --git a/src/lsmsvgview.c b/src/lsmsvgview.c
index b3635d0..e3e3926 100644
--- a/src/lsmsvgview.c
+++ b/src/lsmsvgview.c
@@ -800,27 +800,6 @@ _set_color (LsmSvgView *view, LsmSvgViewPaintOperation operation,
 }
 
 static void
-render_marker (LsmSvgView *view, LsmSvgMarkerElement *marker,
-	       double x, double y,
-	       double stroke_width, double vertex_angle)
-{
-	cairo_t *cairo;
-
-	if (marker == NULL)
-		return;
-
-	cairo = view->dom_view.cairo;
-
-	cairo_save (cairo);
-
-	cairo_translate (cairo, x, y);
-
-	lsm_svg_marker_element_render (marker, view,
-				       stroke_width, vertex_angle);
-	cairo_restore (cairo);
-}
-
-static void
 paint (LsmSvgView *view)
 {
 	LsmSvgElement *element;
@@ -927,6 +906,12 @@ paint (LsmSvgView *view)
 		cairo_path_data_t *data;
 		cairo_path_data_t *next_data;
 		double stroke_width;
+		double prev_x, prev_y;
+		double x, y;
+		double next_x, next_y;
+		cairo_path_data_type_t type;
+		cairo_path_data_type_t next_type;
+		double angle;
 		int i;
 
 		marker = lsm_svg_document_get_element_by_url (LSM_SVG_DOCUMENT (view->dom_view.document),
@@ -952,42 +937,99 @@ paint (LsmSvgView *view)
 
 		if (path->num_data > 0) {
 			next_data = &path->data[0];
+			next_type = next_data->header.type;
+
+			if (next_type == CAIRO_PATH_CURVE_TO) {
+				next_x = next_data[3].point.x;
+				next_y = next_data[3].point.y;
+			} else {
+				next_x = next_data[1].point.x;
+				next_y = next_data[1].point.y;
+			}
 
-				for (i = 0; i < path->num_data; i += path->data[i].header.length) {
+			for (i = 0; i < path->num_data; i += path->data[i].header.length) {
+				data = next_data;
 
-					data = next_data;
+				prev_x = x;
+				prev_y = y;
+				x = next_x;
+				y = next_y;
+				type = next_type;
 
-					if (i + path->data[i].header.length < path->num_data)
-						next_data = &path->data[i + path->data[i].header.length];
-					else
-						next_data = NULL;
-
-					if (data->header.type == CAIRO_PATH_CLOSE_PATH) {
-						marker = NULL;
-					} else if (next_data == NULL ||
-						   next_data->header.type == CAIRO_PATH_MOVE_TO) {
-						marker = marker_end;
-					} else if (data->header.type == CAIRO_PATH_MOVE_TO) {
-						marker = marker_start;
+				if (i + path->data[i].header.length < path->num_data) {
+					next_data = &path->data[i + path->data[i].header.length];
+					next_type = next_data->header.type;
+
+					if (next_type == CAIRO_PATH_CURVE_TO) {
+						next_x = next_data[3].point.x;
+						next_y = next_data[3].point.y;
 					} else {
-						marker = marker_mid;
+						next_x = next_data[1].point.x;
+						next_y = next_data[1].point.y;
 					}
+				} else {
+					next_data = NULL;
+					next_type = CAIRO_PATH_MOVE_TO;
+					next_x = 0.0;
+					next_y = 0.0;
+				}
 
-					if (marker != NULL) {
-						double x, y;
+				if (data->header.type == CAIRO_PATH_CLOSE_PATH) {
+					marker = NULL;
+				} else if (next_data == NULL ||
+					   next_data->header.type == CAIRO_PATH_MOVE_TO) {
+					marker = marker_end;
+					if (type == CAIRO_PATH_CURVE_TO)
+						angle = atan2 (y - data[2].point.y,
+							       x - data[2].point.x);
+					else
+						angle = atan2 (y - prev_y, x - prev_x);
+				} else if (data->header.type == CAIRO_PATH_MOVE_TO) {
+					marker = marker_start;
+					if (next_type == CAIRO_PATH_CURVE_TO)
+						angle = atan2 (data[1].point.y - y,
+							       data[1].point.x - x);
+					else
+						angle = atan2 (next_y - y, next_x - x);
+				} else {
+					double xdifin, ydifin, xdifout, ydifout, intot, outtot;
 
-						if (data->header.type == CAIRO_PATH_CURVE_TO) {
-							x = data[3].point.x;
-							y = data[3].point.y;
-						} else {
-							x = data[1].point.x;
-							y = data[1].point.y;
-						}
+					marker = marker_mid;
 
-						render_marker (view, LSM_SVG_MARKER_ELEMENT (marker),
-							       x, y, stroke_width, 0.0);
+					if (type == CAIRO_PATH_CURVE_TO) {
+						xdifin = x - data[2].point.x;
+						ydifin = y - data[2].point.y;
+					} else {
+						xdifin = x - prev_x;
+						ydifin = y - prev_y;
 					}
+					if (next_type == CAIRO_PATH_CURVE_TO) {
+						xdifout = data[3].point.x - x;
+						ydifout = data[3].point.y - y;
+					} else {
+						xdifout = next_x - x;
+						ydifout = next_y - y;
+					}
+
+					intot = sqrt (xdifin * xdifin + ydifin * ydifin);
+					outtot = sqrt (xdifout * xdifout + ydifout * ydifout);
+
+					xdifin /= intot;
+					ydifin /= intot;
+					xdifout /= outtot;
+					ydifout /= outtot;
+
+					angle = atan2 ((ydifin + ydifout) / 2, (xdifin + xdifout) / 2);
+				}
+
+				if (marker != NULL) {
+					cairo_save (cairo);
+					cairo_translate (cairo, x, y);
+					lsm_svg_marker_element_render (LSM_SVG_MARKER_ELEMENT (marker), view,
+								       stroke_width, angle);
+					cairo_restore (cairo);
 				}
+			}
 
 			cairo_path_destroy (path);
 		}