Issue #2714 - Implement the Visual Viewport API

This DOM/Web API is entirely irrelevant for desktop use. We give back the width/height of the root scrollframe of content and for scale we pass forward our dpp resolution (usually 1.0). Since we have no "no touch" zones in our content on desktop,. the rest (origin and offset) is hard-coded to (0,0).
2026-09-05 15:28:39 +09:00 · 2025-07-21 11:08:16 +02:00 · 2025-07-21 11:08:16 +02:00 · a036cfeb69
commit a036cfeb69
parent ace2c1c1ee
11 changed files with 246 additions and 0 deletions
--- a/dom/base/VisualViewport.cpp
+++ b/dom/base/VisualViewport.cpp
@ -0,0 +1,144 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "VisualViewport.h"
+#include "nsIScrollableFrame.h"
+#include "nsIDocShell.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+VisualViewport::VisualViewport(nsPIDOMWindowInner* aWindow)
+  : DOMEventTargetHelper(aWindow)
+{
+}
+
+VisualViewport::VisualViewport(nsIGlobalObject* aGlobal)
+  : DOMEventTargetHelper(aGlobal)
+{
+}
+
+VisualViewport::~VisualViewport()
+{
+}
+
+/* virtual */
+JSObject*
+VisualViewport::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return VisualViewportBinding::Wrap(aCx, this, aGivenProto);
+}
+
+/* XXXMC: We are effectively getting the size from the root scrollframe of the content
+ * and the scale from our DPP resolution.
+ * Since we are only on desktop, by definition have full view size (no "notch" or
+ * other mobile "don't touch" areas), we are hard-coding:
+ * - VisualViewportOffset = (0,0)
+ * - PageLeft/PageTop = 0.0
+ * - OffsetLeft/OffsetTop = 0.0
+ */
+ 
+CSSSize
+VisualViewport::VisualViewportSize() const
+{
+  CSSSize size = CSSSize(0,0);
+
+  nsIPresShell* presShell = GetPresShell();
+  if (presShell) {
+    nsIScrollableFrame* sf = presShell->GetRootScrollFrameAsScrollable();
+    if (sf) {
+      size = CSSRect::FromAppUnits(sf->GetScrollPortRect().Size());
+    }
+  }
+  return size;
+}
+
+double
+VisualViewport::Width() const
+{
+  CSSSize size = VisualViewportSize();
+  return size.width;
+}
+
+double
+VisualViewport::Height() const
+{
+  CSSSize size = VisualViewportSize();
+  return size.height;
+}
+
+double
+VisualViewport::Scale() const
+{
+  double scale = 1;
+  nsIPresShell* presShell = GetPresShell();
+  if (presShell) {
+    scale = presShell->GetResolution();
+  }
+  return scale;
+}
+
+CSSPoint
+VisualViewport::VisualViewportOffset() const
+{
+  CSSPoint offset = CSSPoint(0,0);
+  return offset;
+}
+
+CSSPoint
+VisualViewport::LayoutViewportOffset() const
+{
+  CSSPoint offset = CSSPoint(0,0);
+
+  nsIPresShell* presShell = GetPresShell();
+  if (presShell) {
+    nsIScrollableFrame* sf = presShell->GetRootScrollFrameAsScrollable();
+    if (sf) {
+      offset = CSSPoint::FromAppUnits(sf->GetScrollPosition());
+    }
+  }
+  return offset;
+}
+
+double
+VisualViewport::PageLeft() const
+{
+  return 0.0;
+}
+
+double
+VisualViewport::PageTop() const
+{
+  return 0.0;
+}
+
+double
+VisualViewport::OffsetLeft() const
+{
+  return 0.0;
+}
+
+double
+VisualViewport::OffsetTop() const
+{
+  return 0.0;
+}
+
+nsIPresShell*
+VisualViewport::GetPresShell() const
+{
+  nsCOMPtr<nsPIDOMWindowInner> window = GetOwner();
+  if (!window) {
+    return nullptr;
+  }
+
+  nsIDocShell* docShell = window->GetDocShell();
+  if (!docShell) {
+    return nullptr;
+  }
+
+  return docShell->GetPresShell();
+}