script: add Image.Crop(x, y, width, height)

The script plugin currently allows pixel buffers to be resized and
scaled, but provides no mechanism for script theme authors to just crop
the buffer, which is necessary for images that cannot be stretched,
such as progress bars with gradients.

This commit adds that feature as a new Crop method.

src/plugins/splash/script/script-lib-image.c

@@ -131,6 +131,25 @@ static script_return_t image_rotate (script_state_t *state,
         return script_return_obj_null ();
 }
 
+static script_return_t image_crop (script_state_t *state,
+                                   void           *user_data)
+{
+        script_lib_image_data_t *data = user_data;
+        ply_pixel_buffer_t *image = script_obj_as_native_of_class (state->this, data->class);
+        int x = script_obj_hash_get_number (state->local, "x");
+        int y = script_obj_hash_get_number (state->local, "y");
+        int width = script_obj_hash_get_number (state->local, "width");
+        int height = script_obj_hash_get_number (state->local, "height");
+
+        if (image) {
+                ply_rectangle_t clip_area = { 0, 0, width, height };
+                ply_pixel_buffer_t *new_image = ply_pixel_buffer_new (width, height);
+                ply_pixel_buffer_fill_with_buffer_with_clip (new_image, image, -x, -y, &clip_area);
+                return script_return_obj (script_obj_new_native (new_image, data->class));
+        }
+        return script_return_obj_null ();
+}
+
 static script_return_t image_scale (script_state_t *state,
                                     void           *user_data)
 {
@@ -263,6 +282,15 @@ script_lib_image_data_t *script_lib_image_setup (script_state_t *state,
                                     data,
                                     "angle",
                                     NULL);
+        script_add_native_function (image_hash,
+                                    "_Crop",
+                                    image_crop,
+                                    data,
+                                    "x",
+                                    "y",
+                                    "width",
+                                    "height",
+                                    NULL);
         script_add_native_function (image_hash,
                                     "_Scale",
                                     image_scale,

src/plugins/splash/script/script-lib-image.script

@@ -9,6 +9,11 @@ Image.Rotate = fun (angle)
   return Image.Adopt (this._Rotate(angle));
 };
 
+Image.Crop = fun (x, y, width, height)
+{
+  return Image.Adopt (this._Crop(x, y, width, height));
+};
+
 Image.Scale = fun (width, height)
 {
   return Image.Adopt (this._Scale(width, height));