[seed] I don't understand canvas...some more work on handling state correctly

[Robert Carr <racarr src gnome org>]

commit 2dd8699f08cecceeecc68115797f0571a47afbd0
Author: Robert Carr <racarr mireia (none)>
Date:   Tue Apr 14 19:18:22 2009 -0400

    I don't understand canvas...some more work on handling state correctly
---
 modules/canvas/run-tests.js  |   38 ++++++++++++++++++++------------------
 modules/canvas/seed-canvas.c |   17 ++++++++---------
 2 files changed, 28 insertions(+), 27 deletions(-)

diff --git a/modules/canvas/run-tests.js b/modules/canvas/run-tests.js
index a36b8fb..9a0c47a 100755
--- a/modules/canvas/run-tests.js
+++ b/modules/canvas/run-tests.js
@@ -377,25 +377,27 @@ var compositeTypes = [
   'destination-over','destination-in','destination-out','destination-atop',
   'lighter','darker','copy','xor'
 ];
-function test17(ctx){
-  for (var i=0;i<3;i++){
-    for (var j = 0;j<4;j++){
-        // draw rectangle
-      ctx.fillStyle = "#09f";
-      ctx.fillRect(70*i,70*j,40,40);
-
-      // set composite property
-      Seed.print(compositeTypes[i*4+j])
-      ctx.globalCompositeOperation = compositeTypes[i*4+j];
-
-      // draw circle
-      ctx.fillStyle = "#f30";
-      ctx.beginPath();
-      ctx.arc(35+70*i,35+70*j,17,0,Math.PI*2,true);
-      ctx.fill();
-	}
+  function test17(ctx){
+    for (var i=0;i<3;i++){
+      for (var j = 0;j<4;j++){
+          // draw rectangle
+	ctx.save();
+	ctx.fillStyle = "#09f";
+	ctx.fillRect(70*i,70*j,40,40);
+
+	// set composite property
+//	Seed.print(compositeTypes[i*4+j])
+	ctx.globalCompositeOperation = compositeTypes[i*4+j];
+
+	// draw circle
+	ctx.fillStyle = "#f30";
+	ctx.beginPath();
+	ctx.arc(30+70*i,30+70*j,17,0,Math.PI*2,true);
+	ctx.fill();
+	ctx.restore();
+      }
+    }
   }
-}
 
 
 tests = [test1, test2, test3, test4,
diff --git a/modules/canvas/seed-canvas.c b/modules/canvas/seed-canvas.c
index 5f4daec..87ed220 100644
--- a/modules/canvas/seed-canvas.c
+++ b/modules/canvas/seed-canvas.c
@@ -281,6 +281,7 @@ seed_canvas_update_stroke_style (SeedContext ctx,
       priv->styles = g_slist_prepend(priv->styles, g_new0(SeedCanvasStyle, 1));
       ((SeedCanvasStyle *) priv->styles->data)->global_opacity = 1;
       ((SeedCanvasStyle *) priv->styles->data)->fill.a = 1;
+      ((SeedCanvasStyle *) priv->styles->data)->operator = CAIRO_OPERATOR_OVER;
     }
   
   style = (SeedCanvasStyle *)priv->styles->data;
@@ -309,6 +310,7 @@ seed_canvas_update_fill_style (SeedContext ctx,
       priv->styles = g_slist_prepend(priv->styles, g_new0(SeedCanvasStyle, 1));
       ((SeedCanvasStyle *) priv->styles->data)->global_opacity = 1;
       ((SeedCanvasStyle *) priv->styles->data)->stroke.a = 1;
+      ((SeedCanvasStyle *) priv->styles->data)->operator = CAIRO_OPERATOR_OVER;
     }
   
   style = (SeedCanvasStyle *)priv->styles->data;
@@ -338,6 +340,7 @@ seed_canvas_update_global_alpha (SeedContext ctx,
       ((SeedCanvasStyle *) priv->styles->data)->global_opacity = 1;
       ((SeedCanvasStyle *) priv->styles->data)->stroke.a = 1;
       ((SeedCanvasStyle *) priv->styles->data)->fill.a = 1;
+      ((SeedCanvasStyle *) priv->styles->data)->operator = CAIRO_OPERATOR_OVER;
     }
 
   style = (SeedCanvasStyle *)priv->styles->data;
@@ -363,6 +366,7 @@ seed_canvas_update_global_composite (SeedContext ctx,
       ((SeedCanvasStyle *) priv->styles->data)->global_opacity = 1;
       ((SeedCanvasStyle *) priv->styles->data)->stroke.a = 1;
       ((SeedCanvasStyle *) priv->styles->data)->fill.a = 1;
+      ((SeedCanvasStyle *) priv->styles->data)->operator = CAIRO_OPERATOR_OVER;
     }
 
   style = (SeedCanvasStyle *)priv->styles->data;
@@ -394,6 +398,8 @@ seed_canvas_update_global_composite (SeedContext ctx,
   else
     style->operator = CAIRO_OPERATOR_OVER;
   
+  cairo_set_operator (cr, style->operator);
+  
   g_free (composite_op);
   
   return TRUE;
@@ -473,10 +479,7 @@ seed_canvas_apply_stroke_style (SeedCanvasStyle *style,
 			style->stroke.g,
 			style->stroke.b,
 			style->stroke.a * style->global_opacity);
-  if (style->operator)
-    cairo_set_operator (cr, style->operator);
-  else
-    cairo_set_operator (cr, CAIRO_OPERATOR_OVER);
+  cairo_set_operator (cr, style->operator);
 }
 
 void
@@ -488,11 +491,7 @@ seed_canvas_apply_fill_style (SeedCanvasStyle *style,
 			style->fill.g,
 			style->fill.b,
 			style->fill.a * style->global_opacity);
-  if (style->operator)
-    cairo_set_operator (cr, style->operator);
-  else
-    cairo_set_operator (cr, CAIRO_OPERATOR_OVER);
-      
+  cairo_set_operator (cr, style->operator);
 }
 
 SeedValue