1 files changed, 285 insertions, 0 deletions
diff --git a/layout/base/ZoomConstraintsClient.cpp b/layout/base/ZoomConstraintsClient.cpp
new file mode 100644
index 0000000000..183f3eb22e
--- /dev/null
+++ b/layout/base/ZoomConstraintsClient.cpp
@@ -0,0 +1,285 @@
+/* -*- 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 "ZoomConstraintsClient.h"
+
+#include <inttypes.h>
+#include "mozilla/layers/APZCCallbackHelper.h"
+#include "mozilla/layers/ScrollableLayerGuid.h"
+#include "mozilla/layers/ZoomConstraints.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/StaticPrefs_apz.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/Event.h"
+#include "nsIFrame.h"
+#include "nsIScrollableFrame.h"
+#include "nsLayoutUtils.h"
+#include "nsPoint.h"
+#include "nsView.h"
+#include "nsViewportInfo.h"
+#include "Units.h"
+#include "UnitTransforms.h"
+
+static mozilla::LazyLogModule sApzZoomLog("apz.zoom");
+#define ZCC_LOG(...) MOZ_LOG(sApzZoomLog, LogLevel::Debug, (__VA_ARGS__))
+
+NS_IMPL_ISUPPORTS(ZoomConstraintsClient, nsIDOMEventListener, nsIObserver)
+
+#define DOM_META_ADDED u"DOMMetaAdded"_ns
+#define DOM_META_CHANGED u"DOMMetaChanged"_ns
+#define FULLSCREEN_CHANGED u"fullscreenchange"_ns
+#define BEFORE_FIRST_PAINT "before-first-paint"_ns
+#define COMPOSITOR_REINITIALIZED "compositor-reinitialized"_ns
+#define NS_PREF_CHANGED "nsPref:changed"_ns
+
+using namespace mozilla;
+using namespace mozilla::dom;
+using namespace mozilla::layers;
+
+ZoomConstraintsClient::ZoomConstraintsClient()
+    : mDocument(nullptr),
+      mPresShell(nullptr),
+      mZoomConstraints(false, false, CSSToParentLayerScale(1.f),
+                       CSSToParentLayerScale(1.f)) {}
+
+ZoomConstraintsClient::~ZoomConstraintsClient() = default;
+
+static nsIWidget* GetWidget(PresShell* aPresShell) {
+  if (!aPresShell) {
+    return nullptr;
+  }
+  if (nsIFrame* rootFrame = aPresShell->GetRootFrame()) {
+#if defined(MOZ_WIDGET_ANDROID) || defined(MOZ_WIDGET_UIKIT)
+    return rootFrame->GetNearestWidget();
+#else
+    if (nsView* view = rootFrame->GetView()) {
+      return view->GetWidget();
+    }
+#endif
+  }
+  return nullptr;
+}
+
+void ZoomConstraintsClient::Destroy() {
+  if (!(mPresShell && mDocument)) {
+    return;
+  }
+
+  ZCC_LOG("Destroying %p\n", this);
+
+  if (mEventTarget) {
+    mEventTarget->RemoveEventListener(DOM_META_ADDED, this, false);
+    mEventTarget->RemoveEventListener(DOM_META_CHANGED, this, false);
+    mEventTarget->RemoveSystemEventListener(FULLSCREEN_CHANGED, this, false);
+    mEventTarget = nullptr;
+  }
+
+  nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+  if (observerService) {
+    observerService->RemoveObserver(this, BEFORE_FIRST_PAINT.Data());
+    observerService->RemoveObserver(this, COMPOSITOR_REINITIALIZED.Data());
+  }
+
+  Preferences::RemoveObserver(this, "browser.ui.zoom.force-user-scalable");
+
+  if (mGuid) {
+    if (nsIWidget* widget = GetWidget(mPresShell)) {
+      ZCC_LOG("Sending null constraints in %p for { %u, %" PRIu64 " }\n", this,
+              mGuid->mPresShellId, mGuid->mScrollId);
+      widget->UpdateZoomConstraints(mGuid->mPresShellId, mGuid->mScrollId,
+                                    Nothing());
+      mGuid = Nothing();
+    }
+  }
+
+  mDocument = nullptr;
+  mPresShell = nullptr;
+}
+
+void ZoomConstraintsClient::Init(PresShell* aPresShell, Document* aDocument) {
+  if (!(aPresShell && aDocument)) {
+    return;
+  }
+
+  mPresShell = aPresShell;
+  mDocument = aDocument;
+
+  if (nsCOMPtr<nsPIDOMWindowOuter> window = mDocument->GetWindow()) {
+    mEventTarget = window->GetParentTarget();
+  }
+  if (mEventTarget) {
+    mEventTarget->AddEventListener(DOM_META_ADDED, this, false);
+    mEventTarget->AddEventListener(DOM_META_CHANGED, this, false);
+    mEventTarget->AddSystemEventListener(FULLSCREEN_CHANGED, this, false);
+  }
+
+  nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+  if (observerService) {
+    observerService->AddObserver(this, BEFORE_FIRST_PAINT.Data(), false);
+    observerService->AddObserver(this, COMPOSITOR_REINITIALIZED.Data(), false);
+  }
+
+  Preferences::AddStrongObserver(this, "browser.ui.zoom.force-user-scalable");
+}
+
+NS_IMETHODIMP
+ZoomConstraintsClient::HandleEvent(dom::Event* event) {
+  nsAutoString type;
+  event->GetType(type);
+
+  if (type.Equals(DOM_META_ADDED)) {
+    ZCC_LOG("Got a dom-meta-added event in %p\n", this);
+    RefreshZoomConstraints();
+  } else if (type.Equals(DOM_META_CHANGED)) {
+    ZCC_LOG("Got a dom-meta-changed event in %p\n", this);
+    RefreshZoomConstraints();
+  } else if (type.Equals(FULLSCREEN_CHANGED)) {
+    ZCC_LOG("Got a fullscreen-change event in %p\n", this);
+    RefreshZoomConstraints();
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+ZoomConstraintsClient::Observe(nsISupports* aSubject, const char* aTopic,
+                               const char16_t* aData) {
+  if (SameCOMIdentity(aSubject, ToSupports(mDocument)) &&
+      BEFORE_FIRST_PAINT.EqualsASCII(aTopic)) {
+    ZCC_LOG("Got a before-first-paint event in %p\n", this);
+    RefreshZoomConstraints();
+  } else if (COMPOSITOR_REINITIALIZED.EqualsASCII(aTopic)) {
+    ZCC_LOG("Got a compositor-reinitialized notification in %p\n", this);
+    RefreshZoomConstraints();
+  } else if (NS_PREF_CHANGED.EqualsASCII(aTopic)) {
+    ZCC_LOG("Got a pref-change event in %p\n", this);
+    // We need to run this later because all the pref change listeners need
+    // to execute before we can be guaranteed that
+    // StaticPrefs::browser_ui_zoom_force_user_scalable() returns the updated
+    // value.
+
+    RefPtr<nsRunnableMethod<ZoomConstraintsClient>> event =
+        NewRunnableMethod("ZoomConstraintsClient::RefreshZoomConstraints", this,
+                          &ZoomConstraintsClient::RefreshZoomConstraints);
+    mDocument->Dispatch(TaskCategory::Other, event.forget());
+  }
+  return NS_OK;
+}
+
+void ZoomConstraintsClient::ScreenSizeChanged() {
+  ZCC_LOG("Got a screen-size change notification in %p\n", this);
+  RefreshZoomConstraints();
+}
+
+static mozilla::layers::ZoomConstraints ComputeZoomConstraintsFromViewportInfo(
+    const nsViewportInfo& aViewportInfo, Document* aDocument) {
+  mozilla::layers::ZoomConstraints constraints;
+  constraints.mAllowZoom = aViewportInfo.IsZoomAllowed() &&
+                           nsLayoutUtils::AllowZoomingForDocument(aDocument);
+  constraints.mAllowDoubleTapZoom =
+      constraints.mAllowZoom && StaticPrefs::apz_allow_double_tap_zooming();
+  if (constraints.mAllowZoom) {
+    constraints.mMinZoom.scale = aViewportInfo.GetMinZoom().scale;
+    constraints.mMaxZoom.scale = aViewportInfo.GetMaxZoom().scale;
+  } else {
+    constraints.mMinZoom.scale = aViewportInfo.GetDefaultZoom().scale;
+    constraints.mMaxZoom.scale = aViewportInfo.GetDefaultZoom().scale;
+  }
+  return constraints;
+}
+
+void ZoomConstraintsClient::RefreshZoomConstraints() {
+  mZoomConstraints = ZoomConstraints(false, false, CSSToParentLayerScale(1.f),
+                                     CSSToParentLayerScale(1.f));
+
+  nsIWidget* widget = GetWidget(mPresShell);
+  if (!widget) {
+    return;
+  }
+
+  uint32_t presShellId = 0;
+  ScrollableLayerGuid::ViewID viewId = ScrollableLayerGuid::NULL_SCROLL_ID;
+  bool scrollIdentifiersValid =
+      APZCCallbackHelper::GetOrCreateScrollIdentifiers(
+          mDocument->GetDocumentElement(), &presShellId, &viewId);
+  if (!scrollIdentifiersValid) {
+    return;
+  }
+
+  LayoutDeviceIntSize screenSize;
+  if (!nsLayoutUtils::GetContentViewerSize(mPresShell->GetPresContext(),
+                                           screenSize)) {
+    return;
+  }
+
+  nsViewportInfo viewportInfo = mDocument->GetViewportInfo(ViewAs<ScreenPixel>(
+      screenSize, PixelCastJustification::LayoutDeviceIsScreenForBounds));
+
+  mZoomConstraints =
+      ComputeZoomConstraintsFromViewportInfo(viewportInfo, mDocument);
+
+  if (mDocument->Fullscreen()) {
+    ZCC_LOG("%p is in fullscreen, disallowing zooming\n", this);
+    mZoomConstraints.mAllowZoom = false;
+    mZoomConstraints.mAllowDoubleTapZoom = false;
+  }
+
+  if (mDocument->IsStaticDocument()) {
+    ZCC_LOG("%p is in print or print preview, disallowing double tap zooming\n",
+            this);
+    mZoomConstraints.mAllowDoubleTapZoom = false;
+  }
+
+  if (nsContentUtils::IsPDFJS(mDocument->GetPrincipal())) {
+    ZCC_LOG("%p is pdf.js viewer, disallowing double tap zooming\n", this);
+    mZoomConstraints.mAllowDoubleTapZoom = false;
+  }
+
+  // On macOS the OS can send us a double tap zoom event from the touchpad and
+  // there are no touch screen macOS devices so we never wait to see if a second
+  // tap is coming so we can always allow double tap zooming on mac. We need
+  // this because otherwise the width check usually disables it.
+  bool allow_double_tap_always = false;
+#ifdef XP_MACOSX
+  allow_double_tap_always =
+      StaticPrefs::apz_mac_enable_double_tap_zoom_touchpad_gesture();
+#endif
+  if (!allow_double_tap_always && mZoomConstraints.mAllowDoubleTapZoom) {
+    // If the CSS viewport is narrower than the screen (i.e. width <=
+    // device-width) then we disable double-tap-to-zoom behaviour.
+    CSSToLayoutDeviceScale scale =
+        mPresShell->GetPresContext()->CSSToDevPixelScale();
+    if ((viewportInfo.GetSize() * scale).width <= screenSize.width) {
+      mZoomConstraints.mAllowDoubleTapZoom = false;
+    }
+  }
+
+  // We only ever create a ZoomConstraintsClient for an RCD, so the RSF of
+  // the presShell must be the RCD-RSF (if it exists).
+  MOZ_ASSERT(mPresShell->GetPresContext()->IsRootContentDocumentCrossProcess());
+  if (nsIScrollableFrame* rcdrsf =
+          mPresShell->GetRootScrollFrameAsScrollable()) {
+    ZCC_LOG("Notifying RCD-RSF that it is zoomable: %d\n",
+            mZoomConstraints.mAllowZoom);
+    rcdrsf->SetZoomableByAPZ(mZoomConstraints.mAllowZoom);
+  }
+
+  ScrollableLayerGuid newGuid(LayersId{0}, presShellId, viewId);
+  if (mGuid && mGuid.value() != newGuid) {
+    ZCC_LOG("Clearing old constraints in %p for { %u, %" PRIu64 " }\n", this,
+            mGuid->mPresShellId, mGuid->mScrollId);
+    // If the guid changes, send a message to clear the old one
+    widget->UpdateZoomConstraints(mGuid->mPresShellId, mGuid->mScrollId,
+                                  Nothing());
+  }
+  mGuid = Some(newGuid);
+  ZCC_LOG("Sending constraints %s in %p for { %u, %" PRIu64 " }\n",
+          ToString(mZoomConstraints).c_str(), this, presShellId, viewId);
+  widget->UpdateZoomConstraints(presShellId, viewId, Some(mZoomConstraints));
+}