[Commit] cairo-demo/X11 cairo-knockout.c,1.3,1.4

[Carl Worth]

Committed by: cworth

Update of /local/src/CVS/cairo-demo/X11
In directory home.keithp.com:/tmp/cvs-serv7168

Modified Files:
	cairo-knockout.c 
Log Message:
Use cairo_arc in oval_path

Index: cairo-knockout.c
===================================================================
RCS file: /local/src/CVS/cairo-demo/X11/cairo-knockout.c,v
retrieving revision 1.3
retrieving revision 1.4
diff -u -d -r1.3 -r1.4
--- cairo-knockout.c	29 Sep 2003 15:01:03 -0000	1.3
+++ cairo-knockout.c	29 Sep 2003 15:17:00 -0000	1.4
@@ -9,50 +9,37 @@
  * v0.2   1 December  2002 - typo fixes from Keith Packard
  * v0.3  17 April     2003 - Tracking changes in Xr, (Removal of Xr{Push,Pop}Group)
  * v0.4  29 September 2003 - Use cairo_rectangle rather than private rect_path
+ *			     Use cairo_arc for oval_path
  */
 #include <X11/Xlib.h>
 #include <cairo.h>
 #include <math.h>
 #include <stdio.h>
 
-/* Create a path that is roughly a circular oval with
- * radii xr, yr at xc, yc. We only use 4 bezier's
- * but the deviation is already pretty darn small.
- * (max of about 0.02%)
+/* Create a path that is a circular oval with radii xr, yr at xc,
+ * yc. Since we use cairo_arc here it will provide as many splines as
+ * necessary to be extremely accurate. 
  */
 static void
 oval_path (cairo_t *r,
            double xc, double yc,
            double xr, double yr)
 {
-    int i;
-    
-    cairo_new_path (r);
-    cairo_move_to (r, xc + xr, yc);
+    cairo_matrix_t *matrix;
 
-#define TANGENT_MULT (1.65591 / 3.)
-    
-    for (i = 0; i < 4; i++)
-        {
-            double angle1 = ((i + 0) / 2.) * M_PI;
-            double angle2 = ((i + 1) / 2.) * M_PI;
+    matrix = cairo_matrix_create ();
+    cairo_current_matrix (r, matrix);
 
-            double x0 = xc + xr * cos (angle1);
-            double y0 = yc - yr * sin (angle1);
+    cairo_translate (r, xc, yc);
+    cairo_scale (r, 1.0, yr / xr);
+    cairo_move_to (r, 0.0, 0.0);
+    cairo_arc (r,
+               0, 0,
+               xr,
+               0, 2 * M_PI);
 
-            double x1 = x0 - xr * sin (angle1) * TANGENT_MULT;
-            double y1 = y0 - yr * cos (angle1) * TANGENT_MULT;
-            
-            double x3 = xc + xr * cos (angle2);
-            double y3 = yc - yr * sin (angle2);
-            
-            double x2 = x3 + xr * sin (angle2) * TANGENT_MULT;
-            double y2 = y3 + yr * cos (angle2) * TANGENT_MULT;
-            
-            cairo_curve_to (r, x1, y1, x2, y2, x3, y3);
-        }
-    
-    cairo_close_path (r);
+    cairo_set_matrix (r, matrix);
+    cairo_matrix_destroy (matrix);
 }
 
 /* Fill the given area with checks in the standard style
@@ -251,7 +238,7 @@
 
     /* It would be nice to be able to set 'region' as
      * clip for our drawing, then only copy that portion
-     * of our drawing, but Xr doesn't expose the clipping
+     * of our drawing, but Cairo doesn't expose the clipping
      * features of Xrender. So, we redraw the entire
      * bounding rectangle, even if the area is, e.g., L shaped,
      * as frequently happens for exposes.x