Pass the dirty rect down into the blob image

This lets us know which area of the image has changed and is useful
for merging the old blob data and the new blob data.

Author: jrmuizel

webrender/examples/blob.rs

@@ -17,8 +17,8 @@ use std::collections::HashMap;
 use std::collections::hash_map::Entry;
 use std::sync::Arc;
 use std::sync::mpsc::{channel, Receiver, Sender};
-use webrender::api::{self, DisplayListBuilder, DocumentId, LayoutSize, PipelineId, RenderApi,
-                     ResourceUpdates};
+use webrender::api::{self, DeviceUintRect, DisplayListBuilder, DocumentId, LayoutSize, PipelineId,
+                     RenderApi, ResourceUpdates};
 
 // This example shows how to implement a very basic BlobImageRenderer that can only render
 // a checkerboard pattern.
@@ -145,7 +145,7 @@ impl api::BlobImageRenderer for CheckerboardRenderer {
             .insert(key, Arc::new(deserialize_blob(&cmds[..]).unwrap()));
     }
 
-    fn update(&mut self, key: api::ImageKey, cmds: api::BlobImageData) {
+    fn update(&mut self, key: api::ImageKey, cmds: api::BlobImageData, _dirty_rect: Option<DeviceUintRect>) {
         // Here, updating is just replacing the current version of the commands with
         // the new one (no incremental updates).
         self.image_cmds

webrender/src/resource_cache.rs

@@ -430,7 +430,7 @@ impl ResourceCache {
                 self.blob_image_renderer
                     .as_mut()
                     .unwrap()
-                    .update(image_key, mem::replace(blob, BlobImageData::new()));
+                    .update(image_key, mem::replace(blob, BlobImageData::new()), dirty_rect);
             }
 
             ImageResource {

webrender_api/src/image.rs

@@ -151,7 +151,7 @@ pub trait BlobImageResources {
 pub trait BlobImageRenderer: Send {
     fn add(&mut self, key: ImageKey, data: BlobImageData, tiling: Option<TileSize>);
 
-    fn update(&mut self, key: ImageKey, data: BlobImageData);
+    fn update(&mut self, key: ImageKey, data: BlobImageData, dirty_rect: Option<DeviceUintRect>);
 
     fn delete(&mut self, key: ImageKey);
 

wrench/src/blob.rs

@@ -105,7 +105,7 @@ impl BlobImageRenderer for CheckerboardRenderer {
             .insert(key, deserialize_blob(&cmds[..]).unwrap());
     }
 
-    fn update(&mut self, key: ImageKey, cmds: BlobImageData) {
+    fn update(&mut self, key: ImageKey, cmds: BlobImageData, _dirty_rect: Option<DeviceUintRect>) {
         // Here, updating is just replacing the current version of the commands with
         // the new one (no incremental updates).
         self.image_cmds