aboutsummaryrefslogtreecommitdiffstats
path: root/components/script/dom/window.rs
diff options
context:
space:
mode:
authorJosh Matthews <josh@joshmatthews.net>2015-02-19 13:08:50 -0500
committerJosh Matthews <josh@joshmatthews.net>2015-03-03 16:25:40 -0500
commite2c4f5ed6726ed7434197180b301f74a967d3ffc (patch)
tree543d4b085a38fdbc134c945d78fff2b2dec619b4 /components/script/dom/window.rs
parentd9f04180a5d9146f4486ede6fabb9da638cccd41 (diff)
downloadservo-e2c4f5ed6726ed7434197180b301f74a967d3ffc.tar.gz
servo-e2c4f5ed6726ed7434197180b301f74a967d3ffc.zip
Move everything unrelated to the frame tree out of Page and into Document or Window. Reduce the API surface of Page to a bare minimum to allow for easier future removal.
Diffstat (limited to 'components/script/dom/window.rs')
-rw-r--r--components/script/dom/window.rs421
1 files changed, 387 insertions, 34 deletions
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 27b297e21f2..30b1e6baaa0 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -8,50 +8,59 @@ use dom::bindings::codegen::Bindings::FunctionBinding::Function;
use dom::bindings::codegen::Bindings::WindowBinding;
use dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
use dom::bindings::codegen::Bindings::DocumentBinding::DocumentMethods;
-use dom::bindings::codegen::InheritTypes::EventTargetCast;
+use dom::bindings::codegen::InheritTypes::{NodeCast, EventTargetCast};
use dom::bindings::global::global_object_for_js_object;
use dom::bindings::error::{report_pending_exception, Fallible};
use dom::bindings::error::Error::InvalidCharacter;
use dom::bindings::global::GlobalRef;
-use dom::bindings::js::{MutNullableJS, JSRef, Temporary};
-use dom::bindings::utils::Reflectable;
+use dom::bindings::js::{MutNullableJS, JSRef, Temporary, OptionalRootable, RootedReference};
+use dom::bindings::utils::{GlobalStaticData, Reflectable, WindowProxyHandler};
use dom::browsercontext::BrowserContext;
use dom::console::Console;
-use dom::document::Document;
+use dom::document::{Document, DocumentHelpers};
use dom::element::Element;
use dom::eventtarget::{EventTarget, EventTargetHelpers, EventTargetTypeId};
use dom::location::Location;
use dom::navigator::Navigator;
-use dom::node::window_from_node;
+use dom::node::{window_from_node, Node, TrustedNodeAddress, NodeHelpers};
use dom::performance::Performance;
use dom::screen::Screen;
use dom::storage::Storage;
-use layout_interface::{ReflowGoal, ReflowQueryType};
+use layout_interface::{ReflowGoal, ReflowQueryType, LayoutRPC, LayoutChan, Reflow, Msg};
+use layout_interface::{ContentBoxResponse, ContentBoxesResponse};
use page::Page;
use script_task::{TimerSource, ScriptChan};
use script_task::ScriptMsg;
use script_traits::ScriptControlChan;
use timers::{IsInterval, TimerId, TimerManager, TimerCallback};
+use devtools_traits::DevtoolsControlChan;
use msg::compositor_msg::ScriptListener;
-use msg::constellation_msg::LoadData;
+use msg::constellation_msg::{LoadData, PipelineId, SubpageId, ConstellationChan, WindowSizeData};
use net::image_cache_task::ImageCacheTask;
+use net::resource_task::ResourceTask;
use net::storage_task::StorageTask;
+use util::geometry::{self, Au, MAX_RECT};
use util::str::{DOMString,HTML_SPACE_CHARACTERS};
+use geom::{Point2D, Rect, Size2D};
use js::jsapi::JS_EvaluateUCScript;
use js::jsapi::JSContext;
use js::jsapi::{JS_GC, JS_GetRuntime};
use js::jsval::{JSVal, UndefinedValue};
-use js::rust::with_compartment;
+use js::rust::{Cx, with_compartment};
use url::{Url, UrlParser};
use libc;
use rustc_serialize::base64::{FromBase64, ToBase64, STANDARD};
-use std::cell::{Ref, RefMut};
+use std::cell::{Cell, Ref, RefMut};
use std::default::Default;
use std::ffi::CString;
+use std::mem::replace;
+use std::num::Float;
use std::rc::Rc;
+use std::sync::mpsc::{channel, Receiver};
+use std::sync::mpsc::TryRecvError::{Empty, Disconnected};
use time;
#[dom_struct]
@@ -71,18 +80,80 @@ pub struct Window {
screen: MutNullableJS<Screen>,
session_storage: MutNullableJS<Storage>,
timers: TimerManager,
+
+ /// For providing instructions to an optional devtools server.
+ devtools_chan: Option<DevtoolsControlChan>,
+
+ /// A flag to indicate whether the developer tools have requested live updates of
+ /// page changes.
+ devtools_wants_updates: Cell<bool>,
+
+ next_subpage_id: Cell<SubpageId>,
+
+ /// Pending resize event, if any.
+ resize_event: Cell<Option<WindowSizeData>>,
+
+ /// Pipeline id associated with this page.
+ id: PipelineId,
+
+ /// Subpage id associated with this page, if any.
+ subpage_id: Option<SubpageId>,
+
+ /// Unique id for last reflow request; used for confirming completion reply.
+ last_reflow_id: Cell<uint>,
+
+ /// Global static data related to the DOM.
+ dom_static: GlobalStaticData,
+
+ /// The JavaScript context.
+ js_context: DOMRefCell<Option<Rc<Cx>>>,
+
+ /// A handle for communicating messages to the layout task.
+ layout_chan: LayoutChan,
+
+ /// A handle to perform RPC calls into the layout, quickly.
+ layout_rpc: Box<LayoutRPC+'static>,
+
+ /// The port that we will use to join layout. If this is `None`, then layout is not running.
+ layout_join_port: DOMRefCell<Option<Receiver<()>>>,
+
+ /// The current size of the window, in pixels.
+ window_size: Cell<WindowSizeData>,
+
+ /// Associated resource task for use by DOM objects like XMLHttpRequest
+ resource_task: ResourceTask,
+
+ /// A handle for communicating messages to the storage task.
+ storage_task: StorageTask,
+
+ /// A handle for communicating messages to the constellation task.
+ constellation_chan: ConstellationChan,
+
+ /// Pending scroll to fragment event, if any
+ fragment_name: DOMRefCell<Option<String>>,
+
+ /// An enlarged rectangle around the page contents visible in the viewport, used
+ /// to prevent creating display list items for content that is far away from the viewport.
+ page_clip_rect: Cell<Rect<Au>>,
}
impl Window {
pub fn get_cx(&self) -> *mut JSContext {
- let js_info = self.page().js_info();
- (*js_info.as_ref().unwrap().js_context).ptr
+ self.js_context.borrow().as_ref().unwrap().ptr
}
pub fn script_chan(&self) -> Box<ScriptChan+Send> {
self.script_chan.clone()
}
+ pub fn pipeline(&self) -> PipelineId {
+ self.id.clone()
+ }
+
+ pub fn subpage(&self) -> Option<SubpageId> {
+ self.subpage_id.clone()
+ }
+
pub fn control_chan<'a>(&'a self) -> &'a ScriptControlChan {
&self.control_chan
}
@@ -103,16 +174,8 @@ impl Window {
&*self.page
}
- pub fn page_clone(&self) -> Rc<Page> {
- self.page.clone()
- }
-
- pub fn get_url(&self) -> Url {
- self.page().get_url()
- }
-
pub fn storage_task(&self) -> StorageTask {
- self.page().storage_task.clone()
+ self.storage_task.clone()
}
}
@@ -197,12 +260,11 @@ impl<'a> WindowMethods for JSRef<'a, Window> {
}
fn Close(self) {
- self.script_chan.send(ScriptMsg::ExitWindow(self.page.id.clone())).unwrap();
+ self.script_chan.send(ScriptMsg::ExitWindow(self.id.clone())).unwrap();
}
fn Document(self) -> Temporary<Document> {
- let frame = self.page().frame();
- Temporary::new(frame.as_ref().unwrap().document.clone())
+ self.browser_context().as_ref().unwrap().active_document()
}
fn Location(self) -> Temporary<Location> {
@@ -230,7 +292,7 @@ impl<'a> WindowMethods for JSRef<'a, Window> {
args,
timeout,
IsInterval::NonInterval,
- TimerSource::FromWindow(self.page.id.clone()),
+ TimerSource::FromWindow(self.id.clone()),
self.script_chan.clone())
}
@@ -239,7 +301,7 @@ impl<'a> WindowMethods for JSRef<'a, Window> {
args,
timeout,
IsInterval::NonInterval,
- TimerSource::FromWindow(self.page.id.clone()),
+ TimerSource::FromWindow(self.id.clone()),
self.script_chan.clone())
}
@@ -252,7 +314,7 @@ impl<'a> WindowMethods for JSRef<'a, Window> {
args,
timeout,
IsInterval::Interval,
- TimerSource::FromWindow(self.page.id.clone()),
+ TimerSource::FromWindow(self.id.clone()),
self.script_chan.clone())
}
@@ -261,7 +323,7 @@ impl<'a> WindowMethods for JSRef<'a, Window> {
args,
timeout,
IsInterval::Interval,
- TimerSource::FromWindow(self.page.id.clone()),
+ TimerSource::FromWindow(self.id.clone()),
self.script_chan.clone())
}
@@ -330,10 +392,35 @@ impl<'a> WindowMethods for JSRef<'a, Window> {
}
pub trait WindowHelpers {
+ fn clear_js_context(self);
+ fn clear_js_context_for_script_deallocation(self);
fn flush_layout(self, goal: ReflowGoal, query: ReflowQueryType);
fn init_browser_context(self, doc: JSRef<Document>, frame_element: Option<JSRef<Element>>);
fn load_url(self, href: DOMString);
fn handle_fire_timer(self, timer_id: TimerId);
+ fn reflow(self, goal: ReflowGoal, query_type: ReflowQueryType);
+ fn join_layout(self);
+ fn layout(&self) -> &LayoutRPC;
+ fn content_box_query(self, content_box_request: TrustedNodeAddress) -> Rect<Au>;
+ fn content_boxes_query(self, content_boxes_request: TrustedNodeAddress) -> Vec<Rect<Au>>;
+ fn handle_reflow_complete_msg(self, reflow_id: uint);
+ fn handle_resize_inactive_msg(self, new_size: WindowSizeData);
+ fn set_fragment_name(self, fragment: Option<String>);
+ fn steal_fragment_name(self) -> Option<String>;
+ fn set_window_size(self, size: WindowSizeData);
+ fn window_size(self) -> WindowSizeData;
+ fn get_url(self) -> Url;
+ fn resource_task(self) -> ResourceTask;
+ fn devtools_chan(self) -> Option<DevtoolsControlChan>;
+ fn layout_chan(self) -> LayoutChan;
+ fn constellation_chan(self) -> ConstellationChan;
+ fn windowproxy_handler(self) -> WindowProxyHandler;
+ fn get_next_subpage_id(self) -> SubpageId;
+ fn layout_is_idle(self) -> bool;
+ fn set_resize_event(self, event: WindowSizeData);
+ fn steal_resize_event(self) -> Option<WindowSizeData>;
+ fn set_page_clip_rect_with_new_viewport(self, viewport: Rect<f32>) -> bool;
+ fn set_devtools_wants_updates(self, value: bool);
fn IndexedGetter(self, _index: u32, _found: &mut bool) -> Option<Temporary<Window>>;
fn thaw(self);
fn freeze(self);
@@ -373,8 +460,132 @@ impl<'a, T: Reflectable> ScriptHelpers for JSRef<'a, T> {
}
impl<'a> WindowHelpers for JSRef<'a, Window> {
+ fn clear_js_context(self) {
+ *self.js_context.borrow_mut() = None;
+ *self.browser_context.borrow_mut() = None;
+ }
+
+ #[allow(unsafe_blocks)]
+ fn clear_js_context_for_script_deallocation(self) {
+ unsafe {
+ *self.js_context.borrow_for_script_deallocation() = None;
+ *self.browser_context.borrow_for_script_deallocation() = None;
+ }
+ }
+
fn flush_layout(self, goal: ReflowGoal, query: ReflowQueryType) {
- self.page().flush_layout(goal, query);
+ self.reflow(goal, query);
+ }
+
+ /// Reflows the page if it's possible to do so and the page is dirty. This method will wait
+ /// for the layout thread to complete (but see the `TODO` below). If there is no window size
+ /// yet, the page is presumed invisible and no reflow is performed.
+ ///
+ /// TODO(pcwalton): Only wait for style recalc, since we have off-main-thread layout.
+ fn reflow(self, goal: ReflowGoal, query_type: ReflowQueryType) {
+ let document = self.Document().root();
+ let root = document.r().GetDocumentElement().root();
+ let root = match root.r() {
+ Some(root) => root,
+ None => return,
+ };
+
+ debug!("script: performing reflow for goal {:?}", goal);
+
+ let root: JSRef<Node> = NodeCast::from_ref(root);
+ if !root.get_has_dirty_descendants() {
+ debug!("root has no dirty descendants; avoiding reflow");
+ return
+ }
+
+ debug!("script: performing reflow for goal {:?}", goal);
+
+ // Layout will let us know when it's done.
+ let (join_chan, join_port) = channel();
+
+ {
+ let mut layout_join_port = self.layout_join_port.borrow_mut();
+ *layout_join_port = Some(join_port);
+ }
+
+ let last_reflow_id = &self.last_reflow_id;
+ last_reflow_id.set(last_reflow_id.get() + 1);
+
+ let window_size = self.window_size.get();
+
+ // Send new document and relevant styles to layout.
+ let reflow = box Reflow {
+ document_root: root.to_trusted_node_address(),
+ url: self.get_url(),
+ iframe: self.subpage_id.is_some(),
+ goal: goal,
+ window_size: window_size,
+ script_chan: self.control_chan.clone(),
+ script_join_chan: join_chan,
+ id: last_reflow_id.get(),
+ query_type: query_type,
+ page_clip_rect: self.page_clip_rect.get(),
+ };
+
+ let LayoutChan(ref chan) = self.layout_chan;
+ chan.send(Msg::Reflow(reflow)).unwrap();
+
+ debug!("script: layout forked");
+
+ self.join_layout();
+ }
+
+ // FIXME(cgaebel): join_layout is racey. What if the compositor triggers a
+ // reflow between the "join complete" message and returning from this
+ // function?
+
+ /// Sends a ping to layout and waits for the response. The response will arrive when the
+ /// layout task has finished any pending request messages.
+ fn join_layout(self) {
+ let mut layout_join_port = self.layout_join_port.borrow_mut();
+ if let Some(join_port) = replace(&mut *layout_join_port, None) {
+ match join_port.try_recv() {
+ Err(Empty) => {
+ info!("script: waiting on layout");
+ join_port.recv().unwrap();
+ }
+ Ok(_) => {}
+ Err(Disconnected) => {
+ panic!("Layout task failed while script was waiting for a result.");
+ }
+ }
+
+ debug!("script: layout joined")
+ }
+ }
+
+ fn layout(&self) -> &LayoutRPC {
+ &*self.layout_rpc
+ }
+
+ fn content_box_query(self, content_box_request: TrustedNodeAddress) -> Rect<Au> {
+ self.flush_layout(ReflowGoal::ForScriptQuery, ReflowQueryType::ContentBoxQuery(content_box_request));
+ self.join_layout(); //FIXME: is this necessary, or is layout_rpc's mutex good enough?
+ let ContentBoxResponse(rect) = self.layout_rpc.content_box();
+ rect
+ }
+
+ fn content_boxes_query(self, content_boxes_request: TrustedNodeAddress) -> Vec<Rect<Au>> {
+ self.flush_layout(ReflowGoal::ForScriptQuery, ReflowQueryType::ContentBoxesQuery(content_boxes_request));
+ self.join_layout(); //FIXME: is this necessary, or is layout_rpc's mutex good enough?
+ let ContentBoxesResponse(rects) = self.layout_rpc.content_boxes();
+ rects
+ }
+
+ fn handle_reflow_complete_msg(self, reflow_id: uint) {
+ let last_reflow_id = self.last_reflow_id.get();
+ if last_reflow_id == reflow_id {
+ *self.layout_join_port.borrow_mut() = None;
+ }
+ }
+
+ fn handle_resize_inactive_msg(self, new_size: WindowSizeData) {
+ self.window_size.set(new_size);
}
fn init_browser_context(self, doc: JSRef<Document>, frame_element: Option<JSRef<Element>>) {
@@ -383,17 +594,17 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
/// Commence a new URL load which will either replace this window or scroll to a fragment.
fn load_url(self, href: DOMString) {
- let base_url = self.page().get_url();
+ let base_url = self.get_url();
debug!("current page url is {}", base_url);
let url = UrlParser::new().base_url(&base_url).parse(href.as_slice());
// FIXME: handle URL parse errors more gracefully.
let url = url.unwrap();
match url.fragment {
Some(fragment) => {
- self.script_chan.send(ScriptMsg::TriggerFragment(self.page.id, fragment)).unwrap();
+ self.script_chan.send(ScriptMsg::TriggerFragment(self.id, fragment)).unwrap();
},
None => {
- self.script_chan.send(ScriptMsg::TriggerLoad(self.page.id, LoadData::new(url))).unwrap();
+ self.script_chan.send(ScriptMsg::TriggerLoad(self.id, LoadData::new(url))).unwrap();
}
}
}
@@ -403,6 +614,97 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
self.flush_layout(ReflowGoal::ForDisplay, ReflowQueryType::NoQuery);
}
+ fn set_fragment_name(self, fragment: Option<String>) {
+ *self.fragment_name.borrow_mut() = fragment;
+ }
+
+ fn steal_fragment_name(self) -> Option<String> {
+ self.fragment_name.borrow_mut().take()
+ }
+
+ fn set_window_size(self, size: WindowSizeData) {
+ self.window_size.set(size);
+ }
+
+ fn window_size(self) -> WindowSizeData {
+ self.window_size.get()
+ }
+
+ fn get_url(self) -> Url {
+ let doc = self.Document().root();
+ doc.r().url()
+ }
+
+ fn resource_task(self) -> ResourceTask {
+ self.resource_task.clone()
+ }
+
+ fn devtools_chan(self) -> Option<DevtoolsControlChan> {
+ self.devtools_chan.clone()
+ }
+
+ fn layout_chan(self) -> LayoutChan {
+ self.layout_chan.clone()
+ }
+
+ fn constellation_chan(self) -> ConstellationChan {
+ self.constellation_chan.clone()
+ }
+
+ fn windowproxy_handler(self) -> WindowProxyHandler {
+ self.dom_static.windowproxy_handler
+ }
+
+ fn get_next_subpage_id(self) -> SubpageId {
+ let subpage_id = self.next_subpage_id.get();
+ let SubpageId(id_num) = subpage_id;
+ self.next_subpage_id.set(SubpageId(id_num + 1));
+ subpage_id
+ }
+
+ fn layout_is_idle(self) -> bool {
+ self.layout_join_port.borrow().is_none()
+ }
+
+ fn set_resize_event(self, event: WindowSizeData) {
+ self.resize_event.set(Some(event));
+ }
+
+ fn steal_resize_event(self) -> Option<WindowSizeData> {
+ let event = self.resize_event.get();
+ self.resize_event.set(None);
+ event
+ }
+
+ fn set_page_clip_rect_with_new_viewport(self, viewport: Rect<f32>) -> bool {
+ // We use a clipping rectangle that is five times the size of the of the viewport,
+ // so that we don't collect display list items for areas too far outside the viewport,
+ // but also don't trigger reflows every time the viewport changes.
+ static VIEWPORT_EXPANSION: f32 = 2.0; // 2 lengths on each side plus original length is 5 total.
+ let proposed_clip_rect = geometry::f32_rect_to_au_rect(
+ viewport.inflate(viewport.size.width * VIEWPORT_EXPANSION,
+ viewport.size.height * VIEWPORT_EXPANSION));
+ let clip_rect = self.page_clip_rect.get();
+ if proposed_clip_rect == clip_rect {
+ return false;
+ }
+
+ let had_clip_rect = clip_rect != MAX_RECT;
+ if had_clip_rect && !should_move_clip_rect(clip_rect, viewport) {
+ return false;
+ }
+
+ self.page_clip_rect.set(proposed_clip_rect);
+
+ // If we didn't have a clip rect, the previous display doesn't need rebuilding
+ // because it was built for infinite clip (MAX_RECT).
+ had_clip_rect
+ }
+
+ fn set_devtools_wants_updates(self, value: bool) {
+ self.devtools_wants_updates.set(value);
+ }
+
// https://html.spec.whatwg.org/multipage/browsers.html#accessing-other-browsing-contexts
fn IndexedGetter(self, _index: u32, _found: &mut bool) -> Option<Temporary<Window>> {
None
@@ -419,13 +721,28 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
}
impl Window {
- pub fn new(cx: *mut JSContext,
+ pub fn new(js_context: Rc<Cx>,
page: Rc<Page>,
script_chan: Box<ScriptChan+Send>,
control_chan: ScriptControlChan,
compositor: Box<ScriptListener+'static>,
- image_cache_task: ImageCacheTask)
+ image_cache_task: ImageCacheTask,
+ resource_task: ResourceTask,
+ storage_task: StorageTask,
+ devtools_chan: Option<DevtoolsControlChan>,
+ constellation_chan: ConstellationChan,
+ layout_chan: LayoutChan,
+ id: PipelineId,
+ subpage_id: Option<SubpageId>,
+ window_size: WindowSizeData)
-> Temporary<Window> {
+ let layout_rpc: Box<LayoutRPC> = {
+ let (rpc_send, rpc_recv) = channel();
+ let LayoutChan(ref lchan) = layout_chan;
+ lchan.send(Msg::GetRPC(rpc_send)).unwrap();
+ rpc_recv.recv().unwrap()
+ };
+
let win = box Window {
eventtarget: EventTarget::new_inherited(EventTargetTypeId::Window),
script_chan: script_chan,
@@ -435,6 +752,7 @@ impl Window {
page: page,
navigator: Default::default(),
image_cache_task: image_cache_task,
+ devtools_chan: devtools_chan,
browser_context: DOMRefCell::new(None),
performance: Default::default(),
navigation_start: time::get_time().sec as u64,
@@ -442,8 +760,43 @@ impl Window {
screen: Default::default(),
session_storage: Default::default(),
timers: TimerManager::new(),
+ id: id,
+ subpage_id: subpage_id,
+ dom_static: GlobalStaticData::new(),
+ js_context: DOMRefCell::new(Some(js_context.clone())),
+ resource_task: resource_task,
+ storage_task: storage_task,
+ constellation_chan: constellation_chan,
+ page_clip_rect: Cell::new(MAX_RECT),
+ fragment_name: DOMRefCell::new(None),
+ last_reflow_id: Cell::new(0),
+ resize_event: Cell::new(None),
+ next_subpage_id: Cell::new(SubpageId(0)),
+ layout_chan: layout_chan,
+ layout_rpc: layout_rpc,
+ layout_join_port: DOMRefCell::new(None),
+ window_size: Cell::new(window_size),
+ devtools_wants_updates: Cell::new(false),
};
- WindowBinding::Wrap(cx, win)
+ WindowBinding::Wrap(js_context.ptr, win)
}
}
+
+fn should_move_clip_rect(clip_rect: Rect<Au>, new_viewport: Rect<f32>) -> bool{
+ let clip_rect = Rect(Point2D(geometry::to_frac_px(clip_rect.origin.x) as f32,
+ geometry::to_frac_px(clip_rect.origin.y) as f32),
+ Size2D(geometry::to_frac_px(clip_rect.size.width) as f32,
+ geometry::to_frac_px(clip_rect.size.height) as f32));
+
+ // We only need to move the clip rect if the viewport is getting near the edge of
+ // our preexisting clip rect. We use half of the size of the viewport as a heuristic
+ // for "close."
+ static VIEWPORT_SCROLL_MARGIN_SIZE: f32 = 0.5;
+ let viewport_scroll_margin = new_viewport.size * VIEWPORT_SCROLL_MARGIN_SIZE;
+
+ (clip_rect.origin.x - new_viewport.origin.x).abs() <= viewport_scroll_margin.width ||
+ (clip_rect.max_x() - new_viewport.max_x()).abs() <= viewport_scroll_margin.width ||
+ (clip_rect.origin.y - new_viewport.origin.y).abs() <= viewport_scroll_margin.height ||
+ (clip_rect.max_y() - new_viewport.max_y()).abs() <= viewport_scroll_margin.height
+}