4 files changed, 25 insertions, 9 deletions
diff --git a/libdimension/canvas.c b/libdimension/canvas.c
index d53c7ef..4151a0b 100644
--- a/libdimension/canvas.c
+++ b/libdimension/canvas.c
@@ -43,6 +43,7 @@ dmnsn_new_canvas(unsigned int x, unsigned int y)
 
     /* Allocate room for the optimizers */
     canvas->optimizers = dmnsn_new_array(sizeof(dmnsn_canvas_optimizer));
+    canvas->too_late = 0;
   }
 
   return canvas;
@@ -71,10 +72,15 @@ dmnsn_delete_canvas(dmnsn_canvas *canvas)
 }
 
 /* Set a canvas optimizer */
-void
+int
 dmnsn_optimize_canvas(dmnsn_canvas *canvas, dmnsn_canvas_optimizer optimizer)
 {
-  dmnsn_array_push(canvas->optimizers, &optimizer);
+  if (canvas->too_late) {
+    return 1;
+  } else {
+    dmnsn_array_push(canvas->optimizers, &optimizer);
+    return 0;
+  }
 }
 
 /* Set the color of a pixel */
@@ -85,6 +91,9 @@ dmnsn_set_pixel(dmnsn_canvas *canvas, unsigned int x, unsigned int y,
   unsigned int i;
   dmnsn_canvas_optimizer optimizer;
 
+  /* Don't allow any more optimizers */
+  canvas->too_late = 1;
+
   /* Set the pixel */
   canvas->pixels[y*canvas->x + x] = color;
 
diff --git a/libdimension/dimension/canvas.h b/libdimension/dimension/canvas.h
index a14333d..aaf728b 100644
--- a/libdimension/dimension/canvas.h
+++ b/libdimension/dimension/canvas.h
@@ -29,14 +29,15 @@ typedef struct {
   /* width, height */
   unsigned int x, y;
 
+  /* An array of dmnsn_canvas_optimizer's */
+  dmnsn_array *optimizers;
+  int too_late; /* Is it too late to add optimizers? */
+
   /*
    * Stored in first-quadrant representation (origin is bottom-left).  The pixel
    * at (a,b) is accessible as pixels[b*x + a].
    */
   dmnsn_color *pixels;
-
-  /* An array of dmnsn_canvas_optimizer's */
-  dmnsn_array *optimizers;
 } dmnsn_canvas;
 
 typedef struct dmnsn_canvas_optimizer dmnsn_canvas_optimizer;
@@ -59,8 +60,8 @@ dmnsn_canvas *dmnsn_new_canvas(unsigned int x, unsigned int y);
 void dmnsn_delete_canvas(dmnsn_canvas *canvas);
 
 /* Set a canvas optimizer */
-void dmnsn_optimize_canvas(dmnsn_canvas *canvas,
-                           dmnsn_canvas_optimizer optimizer);
+int dmnsn_optimize_canvas(dmnsn_canvas *canvas,
+                          dmnsn_canvas_optimizer optimizer);
 
 /* Pixel accessors */
 
diff --git a/libdimension/gl.c b/libdimension/gl.c
index a37d7f7..20c9af3 100644
--- a/libdimension/gl.c
+++ b/libdimension/gl.c
@@ -51,7 +51,10 @@ dmnsn_gl_optimize_canvas(dmnsn_canvas *canvas)
     return 1;
   }
 
-  dmnsn_optimize_canvas(canvas, optimizer);
+  if (dmnsn_optimize_canvas(canvas, optimizer) != 0) {
+    free(optimizer.ptr);
+    return 1;
+  }
 
   return 0;
 }
diff --git a/libdimension/png.c b/libdimension/png.c
index c8ffc62..76308ca 100644
--- a/libdimension/png.c
+++ b/libdimension/png.c
@@ -54,7 +54,10 @@ dmnsn_png_optimize_canvas(dmnsn_canvas *canvas)
     return 1;
   }
 
-  dmnsn_optimize_canvas(canvas, optimizer);
+  if (dmnsn_optimize_canvas(canvas, optimizer) != 0) {
+    free(optimizer.ptr);
+    return 1;
+  }
 
   return 0;
 }