Move the document extent onto Document

A document without a frame isn't rendered, so its extent is zero. The
extent cache moves from Frame to Document with it, and the body lookup
reuses HTMLDocument.getBody.

src/browser/Frame.zig

@@ -154,14 +154,6 @@ _queued_events: *std.ArrayList(QueuedEvent) = undefined,
 _focus_fixup_pending: bool = false,
 
 _style_manager: StyleManager,
-
-// Element.documentExtent cache, keyed on style version and viewport.
-_document_extent: ?struct {
-    version: usize,
-    viewport_width: u32,
-    viewport_height: u32,
-    extent: Element.DocumentExtent,
-} = null,
 _script_manager: ScriptManager,
 
 _http_owner: HttpClient.Owner,

src/browser/webapi/Document.zig

@@ -82,6 +82,13 @@ _script_created_parser: ?Parser.Streaming = null,
 _close_requested: bool = false,
 _adopted_style_sheets: ?js.Object.Global = null,
 _selection: Selection = .{ ._rc = .init(1) },
+// extent() cache, keyed on style version and viewport.
+_extent: ?struct {
+    version: usize,
+    viewport_width: u32,
+    viewport_height: u32,
+    extent: Extent,
+} = null,
 // Ordered stack of currently-showing popovers
 _open_popovers: std.ArrayList(*Element) = .empty,
 
@@ -495,6 +502,61 @@ pub fn getDocumentElement(self: *Document) ?*Element {
     return null;
 }
 
+pub const Extent = struct { width: f64, height: f64 };
+
+/// The document's size. Height: enough for every synthetic position (5px per
+/// node) and body's stacked children. Width: body's widest child. An inline
+/// size on body stretches both. A document without a frame isn't rendered,
+/// so it has no size.
+pub fn extent(self: *Document) Extent {
+    const frame = self._frame orelse return .{ .width = 0, .height = 0 };
+    const version = frame.page.style_version;
+    const viewport = frame.page.getViewport();
+    if (self._extent) |cached| {
+        if (cached.version == version and cached.viewport_width == viewport.width and cached.viewport_height == viewport.height) {
+            return cached.extent;
+        }
+    }
+
+    var size: Extent = .{ .width = 0, .height = Element.countSubtreeNodes(self.asNode()) * 5.0 };
+    if (self.is(HTMLDocument)) |html_doc| {
+        if (html_doc.getBody()) |html_body| {
+            const body = html_body.asElement();
+            const style_manager = &frame._style_manager;
+            size.height = @max(size.height, body.contentAxis(frame, .height), style_manager.inlineSize(body, .height) orelse 0);
+            size.width = style_manager.inlineSize(body, .width) orelse 0;
+            var child = body.asNode().firstChild();
+            while (child) |node| : (child = node.nextSibling()) {
+                const el = node.is(Element) orelse continue;
+                if (!style_manager.hasDisplayNone(el)) {
+                    size.width = @max(size.width, el.getElementAxis(frame, .width).value);
+                }
+            }
+        }
+    }
+
+    // Whole pixels, like scroll offsets
+    size = .{ .width = @ceil(size.width), .height = @ceil(size.height) };
+    self._extent = .{
+        .version = version,
+        .viewport_width = viewport.width,
+        .viewport_height = viewport.height,
+        .extent = size,
+    };
+    return size;
+}
+
+/// What the viewport scrolls over: the document, at least viewport-sized.
+pub fn scrollSize(self: *Document) Extent {
+    const frame = self._frame orelse return .{ .width = 0, .height = 0 };
+    const size = self.extent();
+    const viewport = frame.page.getViewport();
+    return .{
+        .width = @max(size.width, @as(f64, @floatFromInt(viewport.width))),
+        .height = @max(size.height, @as(f64, @floatFromInt(viewport.height))),
+    };
+}
+
 fn getSelection(self: *Document) *Selection {
     return &self._selection;
 }

src/browser/webapi/Element.zig

@@ -1500,11 +1500,11 @@ pub fn getElementAxis(self: *Element, frame: *Frame, comptime axis: Axis) Axis.S
         }
     }
 
-    // Root containers span the document, see documentExtent.
+    // Root containers span the document, see Document.extent.
     if (root) {
         return .{ .value = switch (axis) {
             .width => 1920.0,
-            .height => if (self.ownerFrame(frame)) |owner| documentExtent(owner).height else 0.0,
+            .height => if (self.asNode().ownerDocument(frame)) |doc| doc.extent().height else 0.0,
         } };
     }
 
@@ -1539,11 +1539,11 @@ fn clientAxis(self: *Element, frame: *Frame, comptime axis: Axis) f64 {
     return self.viewportAxis(frame, axis) orelse self.boxAxis(frame, axis);
 }
 
-/// documentScrollSize, when self is the root scroller (see viewportAxis).
+/// Document.scrollSize, when self is the root scroller (see viewportAxis).
 fn rootScrollSize(self: *Element, frame: *Frame, comptime axis: Axis) ?f64 {
     _ = self.viewportAxis(frame, axis) orelse return null;
-    const owner = self.ownerFrame(frame) orelse return null;
-    return @field(documentScrollSize(owner), @tagName(axis));
+    const doc = self.asNode().ownerDocument(frame) orelse return null;
+    return @field(doc.scrollSize(), @tagName(axis));
 }
 
 fn viewportAxis(self: *Element, frame: *Frame, comptime axis: Axis) ?f64 {
@@ -1751,7 +1751,7 @@ fn scrollExtent(self: *Element, frame: *Frame, comptime axis: Axis) ?f64 {
 //
 // Text children add height only under an explicit width to wrap at.
 // Otherwise almost every element with text would report overflow.
-fn contentAxis(self: *Element, frame: *Frame, comptime axis: Axis) f64 {
+pub fn contentAxis(self: *Element, frame: *Frame, comptime axis: Axis) f64 {
     var total: f64 = 0;
     const owner = self.ownerFrame(frame) orelse return 0;
     const style_manager = &owner._style_manager;
@@ -1915,69 +1915,8 @@ fn calculateDocumentPosition(node: *Node) f64 {
     return position * 5.0; // 5px per node
 }
 
-pub const DocumentExtent = struct { width: f64, height: f64 };
-
-/// The document's size. Height: enough for every synthetic position (5px per
-/// node) and body's stacked children. Width: body's widest child. An inline
-/// size on body stretches both.
-pub fn documentExtent(frame: *Frame) DocumentExtent {
-    const version = frame.page.style_version;
-    const viewport = frame.page.getViewport();
-    if (frame._document_extent) |cached| {
-        if (cached.version == version and cached.viewport_width == viewport.width and cached.viewport_height == viewport.height) {
-            return cached.extent;
-        }
-    }
-
-    const doc = frame.document;
-    var extent: DocumentExtent = .{ .width = 0, .height = countSubtreeNodes(doc.asNode()) * 5.0 };
-    if (findBody(doc)) |body| {
-        const style_manager = &frame._style_manager;
-        extent.height = @max(extent.height, body.contentAxis(frame, .height), style_manager.inlineSize(body, .height) orelse 0);
-        extent.width = style_manager.inlineSize(body, .width) orelse 0;
-        var child = body.asNode().firstChild();
-        while (child) |node| : (child = node.nextSibling()) {
-            const el = node.is(Element) orelse continue;
-            if (!style_manager.hasDisplayNone(el)) {
-                extent.width = @max(extent.width, el.getElementAxis(frame, .width).value);
-            }
-        }
-    }
-
-    // Whole pixels, like scroll offsets
-    extent = .{ .width = @ceil(extent.width), .height = @ceil(extent.height) };
-    frame._document_extent = .{
-        .version = version,
-        .viewport_width = viewport.width,
-        .viewport_height = viewport.height,
-        .extent = extent,
-    };
-    return extent;
-}
-
-/// What the viewport scrolls over: the document, at least viewport-sized.
-pub fn documentScrollSize(frame: *Frame) DocumentExtent {
-    const extent = documentExtent(frame);
-    const viewport = frame.page.getViewport();
-    return .{
-        .width = @max(extent.width, @as(f64, @floatFromInt(viewport.width))),
-        .height = @max(extent.height, @as(f64, @floatFromInt(viewport.height))),
-    };
-}
-
-fn findBody(doc: *Node.Document) ?*Element {
-    const root = doc.getDocumentElement() orelse return null;
-    var child = root.asNode().firstChild();
-    while (child) |node| : (child = node.nextSibling()) {
-        if (node.is(Html.Body)) |body| {
-            return body.asElement();
-        }
-    }
-    return null;
-}
-
 // Counts total nodes in a subtree (node + all descendants)
-fn countSubtreeNodes(node: *Node) f64 {
+pub fn countSubtreeNodes(node: *Node) f64 {
     var count: f64 = 1.0; // Count this node
 
     var child = node.firstChild();

src/browser/webapi/Window.zig

@@ -951,7 +951,7 @@ fn getDevicePixelRatio(_: *const Window, frame: *Frame) f32 {
 
 pub fn scrollTo(self: *Window, opts: Element.ScrollToOpts, y: ?i32, frame: *Frame) !void {
     const o = opts.offsets(y);
-    const size = Element.documentScrollSize(self._frame);
+    const size = self._frame.document.scrollSize();
     const max_x = scrollLimit(size.width, self.getInnerWidth(self._frame));
     const max_y = scrollLimit(size.height, self.getInnerHeight(self._frame));
     const new_x: u32 = if (o.left) |left| @min(@as(u32, @intCast(@max(0, left))), max_x) else self._scroll_pos.x;