[librsvg] rsvg_path_arc(): take an RsvgPathBuilder, not a full RSVGParsePathCtx

[Federico Mena Quintero <federico src gnome org>]

commit 529bc934ce00ea4a21539fc080f45d3be0ee49fb
Author: Federico Mena Quintero <federico gnome org>
Date:   Fri Feb 20 14:42:59 2015 -0600

    rsvg_path_arc(): take an RsvgPathBuilder, not a full RSVGParsePathCtx
    
    The ctx was used to extract the start point for the arc, and to
    set the 'current point' to the arc's end point when the drawing
    is finished.
    
    We now pass in extra arguments for the start point (which don't come
    with the path builder).
    
    Also, added whitespace in the math-y part, because without whitespace
    it makes me sad.
    
    Signed-off-by: Federico Mena Quintero <federico gnome org>

 rsvg-path.c |  155 ++++++++++++++++++++++++++++++++++-------------------------
 1 files changed, 90 insertions(+), 65 deletions(-)
---
diff --git a/rsvg-path.c b/rsvg-path.c
index 859d0b8..2a0775a 100644
--- a/rsvg-path.c
+++ b/rsvg-path.c
@@ -202,28 +202,32 @@ rsvg_path_arc_segment (RsvgPathBuilder *builder,
 
 /**
  * rsvg_path_arc:
- * @ctx: Path context.
+ * @builder: Path builder.
+ * @x1: Starting x coordinate
+ * @y1: Starting y coordinate
  * @rx: Radius in x direction (before rotation).
  * @ry: Radius in y direction (before rotation).
  * @x_axis_rotation: Rotation angle for axes.
  * @large_arc_flag: 0 for arc length <= 180, 1 for arc >= 180.
- * @sweep: 0 for "negative angle", 1 for "positive angle".
- * @x: New x coordinate.
- * @y: New y coordinate.
+ * @sweep_flag: 0 for "negative angle", 1 for "positive angle".
+ * @x2: Ending x coordinate
+ * @y2: Ending y coordinate
  *
  * Add an RSVG arc to the path context.
  **/
 static void
-rsvg_path_arc (RSVGParsePathCtx * ctx,
-               double rx, double ry, double x_axis_rotation,
-               int large_arc_flag, int sweep_flag, double x, double y)
+rsvg_path_arc (RsvgPathBuilder *builder,
+               double x1, double y1,
+               double rx, double ry,
+               double x_axis_rotation,
+               gboolean large_arc_flag, gboolean sweep_flag,
+               double x2, double y2)
 {
 
     /* See Appendix F.6 Elliptical arc implementation notes
        http://www.w3.org/TR/SVG/implnote.html#ArcImplementationNotes */
 
     double f, sinf, cosf;
-    double x1, y1, x2, y2;
     double x1_, y1_;
     double cx_, cy_, cx, cy;
     double gamma;
@@ -232,103 +236,95 @@ rsvg_path_arc (RSVGParsePathCtx * ctx,
 
     int i, n_segs;
 
-    /* Start and end of path segment */
-    x1 = ctx->cp.point.x;
-    y1 = ctx->cp.point.y;
-
-    x2 = x;
-    y2 = y;
-
-    if(x1 == x2 && y1 == y2)
+    if (x1 == x2 && y1 == y2)
         return;
 
     /* X-axis */
     f = x_axis_rotation * M_PI / 180.0;
-    sinf = sin(f);
-    cosf = cos(f);
+    sinf = sin (f);
+    cosf = cos (f);
+
+    rx = fabs (rx);
+    ry = fabs (ry);
 
     /* Check the radius against floading point underflow.
        See http://bugs.debian.org/508443 */
-    if ((fabs(rx) < DBL_EPSILON) || (fabs(ry) < DBL_EPSILON)) {
-        rsvg_path_builder_line_to (&ctx->builder, x, y);
+    if ((rx < DBL_EPSILON) || (ry < DBL_EPSILON)) {
+        rsvg_path_builder_line_to (builder, x2, y2);
         return;
     }
 
-    if(rx < 0)rx = -rx;
-    if(ry < 0)ry = -ry;
-
-    k1 = (x1 - x2)/2;
-    k2 = (y1 - y2)/2;
+    k1 = (x1 - x2) / 2;
+    k2 = (y1 - y2) / 2;
 
     x1_ = cosf * k1 + sinf * k2;
     y1_ = -sinf * k1 + cosf * k2;
 
-    gamma = (x1_*x1_)/(rx*rx) + (y1_*y1_)/(ry*ry);
+    gamma = (x1_ * x1_) / (rx * rx) + (y1_ * y1_) / (ry * ry);
     if (gamma > 1) {
-        rx *= sqrt(gamma);
-        ry *= sqrt(gamma);
+        rx *= sqrt (gamma);
+        ry *= sqrt (gamma);
     }
 
     /* Compute the center */
 
-    k1 = rx*rx*y1_*y1_ + ry*ry*x1_*x1_;
-    if(k1 == 0)    
+    k1 = rx * rx * y1_ * y1_ + ry * ry * x1_ * x1_;
+    if (k1 == 0)
         return;
 
-    k1 = sqrt(fabs((rx*rx*ry*ry)/k1 - 1));
-    if(sweep_flag == large_arc_flag)
+    k1 = sqrt (fabs ((rx * rx * ry * ry) / k1 - 1));
+    if (sweep_flag == large_arc_flag)
         k1 = -k1;
 
-    cx_ = k1*rx*y1_/ry;
-    cy_ = -k1*ry*x1_/rx;
+    cx_ = k1 * rx * y1_ / ry;
+    cy_ = -k1 * ry * x1_ / rx;
     
-    cx = cosf*cx_ - sinf*cy_ + (x1+x2)/2;
-    cy = sinf*cx_ + cosf*cy_ + (y1+y2)/2;
+    cx = cosf * cx_ - sinf * cy_ + (x1 + x2) / 2;
+    cy = sinf * cx_ + cosf * cy_ + (y1 + y2) / 2;
 
     /* Compute start angle */
 
-    k1 = (x1_ - cx_)/rx;
-    k2 = (y1_ - cy_)/ry;
-    k3 = (-x1_ - cx_)/rx;
-    k4 = (-y1_ - cy_)/ry;
+    k1 = (x1_ - cx_) / rx;
+    k2 = (y1_ - cy_) / ry;
+    k3 = (-x1_ - cx_) / rx;
+    k4 = (-y1_ - cy_) / ry;
 
-    k5 = sqrt(fabs(k1*k1 + k2*k2));
-    if(k5 == 0)return;
+    k5 = sqrt (fabs (k1 * k1 + k2 * k2));
+    if (k5 == 0)
+        return;
 
-    k5 = k1/k5;
-    if(k5 < -1)k5 = -1;
-    else if(k5 > 1)k5 = 1;
-    theta1 = acos(k5);
-    if(k2 < 0)theta1 = -theta1;
+    k5 = k1 / k5;
+    k5 = CLAMP (k5, -1, 1);
+    theta1 = acos (k5);
+    if (k2 < 0)
+        theta1 = -theta1;
 
     /* Compute delta_theta */
 
-    k5 = sqrt(fabs((k1*k1 + k2*k2)*(k3*k3 + k4*k4)));
-    if(k5 == 0)return;
+    k5 = sqrt (fabs ((k1 * k1 + k2 * k2) * (k3 * k3 + k4 * k4)));
+    if (k5 == 0)
+        return;
 
-    k5 = (k1*k3 + k2*k4)/k5;
-    if(k5 < -1)k5 = -1;
-    else if(k5 > 1)k5 = 1;
-    delta_theta = acos(k5);
-    if(k1*k4 - k3*k2 < 0)delta_theta = -delta_theta;
+    k5 = (k1 * k3 + k2 * k4) / k5;
+    k5 = CLAMP (k5, -1, 1);
+    delta_theta = acos (k5);
+    if (k1 * k4 - k3 * k2 < 0)
+        delta_theta = -delta_theta;
 
-    if(sweep_flag && delta_theta < 0)
-        delta_theta += M_PI*2;
-    else if(!sweep_flag && delta_theta > 0)
-        delta_theta -= M_PI*2;
+    if (sweep_flag && delta_theta < 0)
+        delta_theta += M_PI * 2;
+    else if (!sweep_flag && delta_theta > 0)
+        delta_theta -= M_PI * 2;
    
     /* Now draw the arc */
 
     n_segs = ceil (fabs (delta_theta / (M_PI * 0.5 + 0.001)));
 
     for (i = 0; i < n_segs; i++)
-        rsvg_path_arc_segment (&ctx->builder, cx, cy,
+        rsvg_path_arc_segment (builder, cx, cy,
                                           theta1 + i * delta_theta / n_segs,
                                theta1 + (i + 1) * delta_theta / n_segs,
                                rx, ry, x_axis_rotation);
-
-    ctx->cp.point.x = x;
-    ctx->cp.point.y = y;
 }
 
 
@@ -504,9 +500,38 @@ rsvg_parse_path_do_cmd (RSVGParsePathCtx * ctx, gboolean final)
         break;
     case 'a':
         if (ctx->param == 7 || final) {
-            rsvg_path_arc (ctx,
-                           ctx->params[0], ctx->params[1], ctx->params[2],
-                           ctx->params[3], ctx->params[4], ctx->params[5], ctx->params[6]);
+            double x1, y1;
+            double rx, ry;
+            double x_axis_rotation;
+            gboolean large_arc_flag;
+            gboolean sweep_flag;
+            double x2, y2;
+
+            x1 = ctx->cp.point.x;
+            y1 = ctx->cp.point.y;
+
+            rx = ctx->params[0];
+            ry = ctx->params[1];
+
+            x_axis_rotation = ctx->params[2];
+
+            large_arc_flag = (ctx->params[3] == 0 ? FALSE : TRUE);
+            sweep_flag = (ctx->params[4] == 0 ? FALSE : TRUE);
+
+            x2 = ctx->params[5];
+            y2 = ctx->params[6];
+
+            rsvg_path_arc (&ctx->builder,
+                           x1, y1,
+                           rx, ry,
+                           x_axis_rotation,
+                           large_arc_flag,
+                           sweep_flag,
+                           x2, y2);
+
+            ctx->cp.point.x = x2;
+            ctx->cp.point.y = y2;
+
             ctx->param = 0;
         }
         break;