separate generate_image_key from add_image for custom image key gener…

…ation

sample/src/main.rs

@@ -102,7 +102,9 @@ fn main() {
     let epoch = Epoch(0);
     let root_background_color = ColorF::new(0.3, 0.0, 0.0, 1.0);
 
-    let vector_img = api.add_image(
+    let vector_img = api.generate_image_key();
+    api.add_image(
+        vector_img,
         ImageDescriptor {
             format: ImageFormat::RGBA8,
             width: 100,
@@ -143,17 +145,20 @@ fn main() {
     );
 
     let sub_clip = {
+        let mask_image = api.generate_image_key();
+        api.add_image(
+            mask_image,
+            ImageDescriptor {
+                width: 2,
+                height: 2,
+                stride: None,
+                format: ImageFormat::A8,
+                is_opaque: true,
+            },
+            ImageData::new(vec![0, 80, 180, 255])
+        );
         let mask = webrender_traits::ImageMask {
-            image: api.add_image(
-                ImageDescriptor {
-                    width: 2,
-                    height: 2,
-                    stride: None,
-                    format: ImageFormat::A8,
-                    is_opaque: true,
-                },
-                ImageData::new(vec![0, 80, 180, 255])
-            ),
+            image: mask_image,
             rect: LayoutRect::new(LayoutPoint::new(75.0, 75.0), LayoutSize::new(100.0, 100.0)),
             repeat: false,
         };

webrender_traits/src/api.rs

@@ -83,19 +83,18 @@ impl RenderApi {
     }
 
     /// Creates an `ImageKey`.
-    pub fn alloc_image(&self) -> ImageKey {
+    pub fn generate_image_key(&self) -> ImageKey {
         let new_id = self.next_unique_id();
         ImageKey::new(new_id.0, new_id.1)
     }
 
-    /// Adds an image and returns the corresponding `ImageKey`.
+    /// Adds an image identified by the `ImageKey`.
     pub fn add_image(&self,
+                     key: ImageKey,
                      descriptor: ImageDescriptor,
-                     data: ImageData) -> ImageKey {
-        let key = self.alloc_image();
+                     data: ImageData) {
         let msg = ApiMsg::AddImage(key, descriptor, data);
         self.api_sender.send(msg).unwrap();
-        key
     }
 
     /// Updates a specific image.

wrench/src/wrench.rs

@@ -302,7 +302,9 @@ impl Wrench {
             _ => panic!("We don't support whatever your crazy image type is, come on"),
         };
         let bytes = image.raw_pixels();
-        let image_key = self.api.add_image(
+        let image_key = self.api.generate_image_key();
+        self.api.add_image(
+            image_key,
             ImageDescriptor {
                 width: image_dims.0,
                 height: image_dims.1,