1 files changed, 29 insertions, 9 deletions
diff --git a/components/script/dom/webglrenderingcontext.rs b/components/script/dom/webglrenderingcontext.rs
index 204426f8063..a3a6764996c 100644
--- a/components/script/dom/webglrenderingcontext.rs
+++ b/components/script/dom/webglrenderingcontext.rs
@@ -1237,21 +1237,41 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
 
     #[allow(unsafe_code)]
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.5
-    unsafe fn GetBufferParameter(&self, _cx: *mut JSContext, target: u32, parameter: u32) -> JSVal {
-        let parameter_matches = match parameter {
-            constants::BUFFER_SIZE |
-            constants::BUFFER_USAGE => true,
-            _ => false,
+    unsafe fn GetBufferParameter(
+        &self,
+        _cx: *mut JSContext,
+        target: u32,
+        parameter: u32,
+    ) -> JSVal {
+        let buffer = match target {
+            constants::ARRAY_BUFFER => self.bound_buffer_array.get(),
+            constants::ELEMENT_ARRAY_BUFFER => self.bound_buffer_element_array.get(),
+            _ => {
+                self.webgl_error(InvalidEnum);
+                return NullValue();
+            }
+        };
+        match parameter {
+            constants::BUFFER_SIZE | constants::BUFFER_USAGE => {},
+            _ => {
+                self.webgl_error(InvalidEnum);
+                return NullValue();
+            }
+        }
+        let buffer = match buffer {
+            Some(buffer) => buffer,
+            None => {
+                self.webgl_error(InvalidOperation);
+                return NullValue();
+            }
         };
 
-        if !parameter_matches {
-            self.webgl_error(InvalidEnum);
-            return NullValue();
+        if parameter == constants::BUFFER_SIZE {
+            return Int32Value(buffer.capacity() as i32);
         }
 
         let (sender, receiver) = webgl_channel().unwrap();
         self.send_command(WebGLCommand::GetBufferParameter(target, parameter, sender));
-
         Int32Value(receiver.recv().unwrap())
     }