Update SVG document handler; circles.

Cope with circles, rounded rects, etc. Not the worlds best
approximation to a circular arc, but it's better than nothing.

1 files changed, 41 insertions, 19 deletions

diff --git a/source/svg/svg-run.c b/source/svg/svg-run.c
index 0a72e508..c65a808f 100644
--- a/source/svg/svg-run.c
+++ b/source/svg/svg-run.c
@@ -51,6 +51,25 @@ static void svg_draw_path(fz_context *ctx, fz_device *dev, svg_document *doc, fz
 		svg_stroke(ctx, dev, doc, path, state);
 }
 
+/*
+	We use the MAGIC number 0.551915 as a bezier subdivision to approximate
+	a quarter circle arc. The reasons for this can be found here:
+	http://mechanicalexpressions.com/explore/geometric-modeling/circle-spline-approximation.pdf
+*/
+static const float MAGIC_CIRCLE = 0.551915f;
+
+static void approx_circle(fz_context *ctx, fz_path *path, float cx, float cy, float rx, float ry)
+{
+	float rxs = rx * MAGIC_CIRCLE;
+	float rys = ry * MAGIC_CIRCLE;
+	fz_moveto(ctx, path, cx, cy+ry);
+	fz_curveto(ctx, path, cx + rxs, cy + ry, cx + rx, cy + rys, cx + rx, cy);
+	fz_curveto(ctx, path, cx + rx, cy - rys, cx + rxs, cy - rys, cx, cy - ry);
+	fz_curveto(ctx, path, cx - rxs, cy - ry, cx - rx, cy - rys, cx - rx, cy);
+	fz_curveto(ctx, path, cx - rx, cy + rys, cx - rxs, cy + rys, cx, cy + ry);
+	fz_closepath(ctx, path);
+}
+
 static void
 svg_run_rect(fz_context *ctx, fz_device *dev, svg_document *doc, fz_xml *node, const svg_state *inherit_state)
 {
@@ -93,13 +112,27 @@ svg_run_rect(fz_context *ctx, fz_device *dev, svg_document *doc, fz_xml *node, c
 	if (w <= 0 || h <= 0)
 		return;
 
-	/* TODO: we need elliptical arcs to draw rounded corners */
-
 	path = fz_new_path(ctx);
-	fz_moveto(ctx, path, x, y);
-	fz_lineto(ctx, path, x + w, y);
-	fz_lineto(ctx, path, x + w, y + h);
-	fz_lineto(ctx, path, x, y + h);
+	if (rx == 0 || ry == 0)
+	{
+		fz_moveto(ctx, path, x, y);
+		fz_lineto(ctx, path, x + w, y);
+		fz_lineto(ctx, path, x + w, y + h);
+		fz_lineto(ctx, path, x, y + h);
+	}
+	else
+	{
+		float rxs = rx * MAGIC_CIRCLE;
+		float rys = rx * MAGIC_CIRCLE;
+		fz_moveto(ctx, path, x + w - rx, y);
+		fz_curveto(ctx, path, x + w - rxs, y, x + w, y + rys, x + w, y + ry);
+		fz_lineto(ctx, path, x + w, y + h - ry);
+		fz_curveto(ctx, path, x + w, y + h - rys, x + w - rxs, y + h, x + w - rx, y + h);
+		fz_lineto(ctx, path, x + rx, y + h);
+		fz_curveto(ctx, path, x + rxs, y + h, x, y + h - rys, x, y + h - rx);
+		fz_lineto(ctx, path, x, y + rx);
+		fz_curveto(ctx, path, x, y + rxs, x + rxs, y, x + rx, y);
+	}
 	fz_closepath(ctx, path);
 
 	svg_draw_path(ctx, dev, doc, path, &local_state);
@@ -131,15 +164,7 @@ svg_run_circle(fz_context *ctx, fz_device *dev, svg_document *doc, fz_xml *node,
 		return;
 
 	path = fz_new_path(ctx);
-	// FIXME!
-	//fz_moveto(ctx, path, cx + r, cy);
-	//fz_arcn(ctx, path, cx, cy, r, 0, 90);
-	//fz_arcn(ctx, path, cx, cy, r, 90, 180);
-	//fz_arcn(ctx, path, cx, cy, r, 180, 270);
-	//fz_arcn(ctx, path, cx, cy, r, 270, 360);
-	//fz_closepath(ctx, path);
-	(void)cx; // avoid compiler warning until this is fixed
-	(void)cy;
+	approx_circle(ctx, path, cx, cy, r, r);
 	svg_draw_path(ctx, dev, doc, path, &local_state);
 	fz_drop_path(ctx, path);
 }
@@ -172,10 +197,7 @@ svg_run_ellipse(fz_context *ctx, fz_device *dev, svg_document *doc, fz_xml *node
 		return;
 
 	path = fz_new_path(ctx);
-	/* TODO: we need elliptic arcs */
-	// TODO: arc...
-	(void)cx; // avoid compiler warning until this is fixed
-	(void)cy;
+	approx_circle(ctx, path, cx, cy, rx, ry);
 	svg_draw_path(ctx, dev, doc, path, &local_state);
 	fz_drop_path(ctx, path);
 }