scroll, SetScrollTop, SetScrollLeft in `dom-element-scroll` with test

1 files changed, 48 insertions, 3 deletions

diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index a56e16356bf..f443fb71da9 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -363,6 +363,19 @@ impl Element {
         !self.overflow_y_is_visible()
     }
 
+    // https://drafts.csswg.org/cssom-view/#scrolling-box
+    fn has_scrolling_box(&self) -> bool {
+        // TODO: scrolling mechanism, such as scrollbar (We don't have scrollbar yet)
+        //       self.has_scrolling_mechanism()
+        self.overflow_x_is_hidden() ||
+        self.overflow_y_is_hidden()
+    }
+
+    fn has_overflow(&self) -> bool {
+        self.ScrollHeight() > self.ClientHeight() ||
+        self.ScrollWidth() > self.ClientWidth()
+    }
+
     // used value of overflow-x is "visible"
     fn overflow_x_is_visible(&self) -> bool {
         let window = window_from_node(self);
@@ -376,6 +389,20 @@ impl Element {
         let overflow_pair = window.overflow_query(self.upcast::<Node>().to_trusted_node_address());
         overflow_pair.y == overflow_y::computed_value::T::visible
     }
+
+    // used value of overflow-x is "hidden"
+    fn overflow_x_is_hidden(&self) -> bool {
+        let window = window_from_node(self);
+        let overflow_pair = window.overflow_query(self.upcast::<Node>().to_trusted_node_address());
+        overflow_pair.x == overflow_x::computed_value::T::hidden
+    }
+
+    // used value of overflow-y is "hidden"
+    fn overflow_y_is_hidden(&self) -> bool {
+        let window = window_from_node(self);
+        let overflow_pair = window.overflow_query(self.upcast::<Node>().to_trusted_node_address());
+        overflow_pair.y == overflow_y::computed_value::T::hidden
+    }
 }
 
 #[allow(unsafe_code)]
@@ -1471,7 +1498,13 @@ impl Element {
                return;
         }
 
-        // Step 10 (TODO)
+        // Step 10
+        if !self.has_css_layout_box() ||
+           !self.has_scrolling_box() ||
+           !self.has_overflow()
+        {
+            return;
+        }
 
         // Step 11
         win.scroll_node(node, x, y, behavior);
@@ -1927,7 +1960,13 @@ impl ElementMethods for Element {
                return;
         }
 
-        // Step 10 (TODO)
+        // Step 10
+        if !self.has_css_layout_box() ||
+           !self.has_scrolling_box() ||
+           !self.has_overflow()
+        {
+            return;
+        }
 
         // Step 11
         win.scroll_node(node, self.ScrollLeft(), y, behavior);
@@ -2020,7 +2059,13 @@ impl ElementMethods for Element {
                return;
         }
 
-        // Step 10 (TODO)
+        // Step 10
+        if !self.has_css_layout_box() ||
+           !self.has_scrolling_box() ||
+           !self.has_overflow()
+        {
+            return;
+        }
 
         // Step 11
         win.scroll_node(node, x, self.ScrollTop(), behavior);