nsView.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */

#ifndef nsView_h__
#define nsView_h__

#include "nsCoord.h"
#include "nsRect.h"
#include "nsPoint.h"
#include "nsRegion.h"
#include "nsCRT.h"
#include "nsCOMPtr.h"
#include "nsIWidgetListener.h"
#include "Units.h"
#include "mozilla/Attributes.h"
#include "mozilla/EventForwards.h"
#include "mozilla/UniquePtr.h"

class nsViewManager;
class nsIWidget;
class nsIFrame;

namespace mozilla {
class PresShell;
namespace widget {
struct InitData;
enum class TransparencyMode : uint8_t;
enum class WindowType : uint8_t;
}  // namespace widget
}  // namespace mozilla

/**
 * nsView's serve two main purposes: 1) a bridge between nsIFrame's and
 * nsIWidget's, 2) linking the frame tree of a(n) (in-process) subdocument with
 * its parent document frame tree. Historically views were used for more things,
 * but their role has been reduced, and could be reduced to nothing in the
 * future (bug 337801 tracks removing views). Views are generally associated
 * with a frame. A view that does not have a frame is called an anonymous view.
 * Some frames also have associated widgets (think os level windows). If a frame
 * has a widget it must also have a view, but not all frames with views will
 * have widgets.
 *
 * Only four types of frames can have a view: root frames (ViewportFrame),
 * subdocument frames (nsSubDocumentFrame),
 * menu popup frames (nsMenuPopupFrame), and list control frames
 * (nsListControlFrame). Root frames and subdocument frames have views to link
 * the two documents together (the frame trees do not link up otherwise).
 * Menu popup frames, and list control frames have views because
 * they (sometimes) need to create widgets.
 * Menu popup frames handles xul popups, which is anything
 * where we need content to go over top the main window at an os level. List
 * control frames handle select popups/dropdowns in non-e10s mode.
 *
 * The term "root view" refers to the root view of a document. Just like root
 * frames, root views can have parent views. Only the root view of the root
 * document in the process will not have a parent.
 *
 * All views are created by their frames except root views. Root views are
 * special. Root views are created in nsDocumentViewer::MakeWindow before the
 * root frame is created, so the root view will not have a frame very early in
 * document creation.
 *
 * Subdocument frames have an anonymous (no frame associated
 * with it) inner view that is a child of their "outer" view.
 *
 * On a subdocument frame the inner view serves as the parent of the
 * root view of the subdocument. The outer and inner view of the subdocument
 * frame belong to the subdocument frame and hence to the parent document. The
 * root view of the subdocument belongs to the subdocument.
 * nsLayoutUtils::GetCrossDocParentFrame and nsPresContext::GetParentPresContext
 * depend on this view structure and are the main way that we traverse across
 * the document boundary in layout.
 *
 * When the load of a new document is started in the subdocument, the creation
 * of the new subdocument and destruction of the old subdocument are not
 * linked. (This creation and destruction is handled in nsDocumentViewer.cpp.)
 * This means that the old and new document will both exist at the same time
 * during the loading of the new document. During this period the inner view of
 * the subdocument parent will be the parent of two root views. This means that
 * during this period there is a choice for which subdocument we draw,
 * nsSubDocumentFrame::GetSubdocumentPresShellForPainting is what makes that
 * choice. Note that this might not be a totally free choice, ie there might be
 * hidden dependencies and bugs if the way we choose is changed.
 *
 * One thing that is special about the root view of a chrome window is that
 * instead of creating a widget for the view, they can "attach" to the
 * existing widget that was created by appshell code or something else. (see
 * nsDocumentViewer::ShouldAttachToTopLevel)
 */

// Enumerated type to indicate the visibility of a layer.
// hide - the layer is not shown.
// show - the layer is shown irrespective of the visibility of
//        the layer's parent.
enum class ViewVisibility : uint8_t { Hide = 0, Show = 1 };

// Public view flags

// Indicates that the view is using auto z-indexing
#define NS_VIEW_FLAG_AUTO_ZINDEX 0x0004

// Indicates that the view is a floating view.
#define NS_VIEW_FLAG_FLOATING 0x0008

//----------------------------------------------------------------------

/**
 * View interface
 *
 * Views are NOT reference counted. Use the Destroy() member function to
 * destroy a view.
 *
 * The lifetime of the view hierarchy is bounded by the lifetime of the
 * view manager that owns the views.
 *
 * Most of the methods here are read-only. To set the corresponding properties
 * of a view, go through nsViewManager.
 */

class nsView final : public nsIWidgetListener {
 public:
  friend class nsViewManager;

  typedef mozilla::LayoutDeviceIntRect LayoutDeviceIntRect;
  typedef mozilla::LayoutDeviceIntRegion LayoutDeviceIntRegion;

  void operator delete(void* ptr) { ::operator delete(ptr); }

  /**
   * Get the view manager which "owns" the view.
   * This method might require some expensive traversal work in the future. If
   * you can get the view manager from somewhere else, do that instead.
   * @result the view manager
   */
  nsViewManager* GetViewManager() const { return mViewManager; }

  /**
   * Find the view for the given widget, if there is one.
   * @return the view the widget belongs to, or null if the widget doesn't
   * belong to any view.
   */
  static nsView* GetViewFor(const nsIWidget* aWidget);

  /**
   * Destroy the view.
   *
   * The view destroys its child views, and destroys and releases its
   * widget (if it has one).
   *
   * Also informs the view manager that the view is destroyed by calling
   * SetRootView(NULL) if the view is the root view and calling RemoveChild()
   * otherwise.
   */
  void Destroy();

  /**
   * Called to get the position of a view.
   * The specified coordinates are relative to the parent view's origin, but
   * are in appunits of this.
   * This is the (0, 0) origin of the coordinate space established by this view.
   * @param x out parameter for x position
   * @param y out parameter for y position
   */
  nsPoint GetPosition() const {
    NS_ASSERTION(!IsRoot() || (mPosX == 0 && mPosY == 0),
                 "root views should always have explicit position of (0,0)");
    return nsPoint(mPosX, mPosY);
  }

  /**
   * Called to get the dimensions and position of the view's bounds.
   * The view's bounds (x,y) are relative to the origin of the parent view, but
   * are in appunits of this.
   * The view's bounds (x,y) might not be the same as the view's position,
   * if the view has content above or to the left of its origin.
   * @param aBounds out parameter for bounds
   */
  nsRect GetBounds() const { return mDimBounds; }

  /**
   * The bounds of this view relative to this view. So this is the same as
   * GetBounds except this is relative to this view instead of the parent view.
   */
  nsRect GetDimensions() const {
    nsRect r = mDimBounds;
    r.MoveBy(-mPosX, -mPosY);
    return r;
  }

  /**
   * Get the offset between the coordinate systems of |this| and aOther.
   * Adding the return value to a point in the coordinate system of |this|
   * will transform the point to the coordinate system of aOther.
   *
   * The offset is expressed in appunits of |this|. So if you are getting the
   * offset between views in different documents that might have different
   * appunits per devpixel ratios you need to be careful how you use the
   * result.
   *
   * If aOther is null, this will return the offset of |this| from the
   * root of the viewmanager tree.
   *
   * This function is fastest when aOther is an ancestor of |this|.
   *
   * NOTE: this actually returns the offset from aOther to |this|, but
   * that offset is added to transform _coordinates_ from |this| to aOther.
   */
  nsPoint GetOffsetTo(const nsView* aOther) const;

  /**
   * Get the offset between the origin of |this| and the origin of aWidget.
   * Adding the return value to a point in the coordinate system of |this|
   * will transform the point to the coordinate system of aWidget.
   *
   * The offset is expressed in appunits of |this|.
   */
  nsPoint GetOffsetToWidget(nsIWidget* aWidget) const;

  /**
   * Takes a point aPt that is in the coordinate system of |this|'s parent view
   * and converts it to be in the coordinate system of |this| taking into
   * account the offset and any app unit per dev pixel ratio differences.
   */
  nsPoint ConvertFromParentCoords(nsPoint aPt) const;

  /**
   * Called to query the visibility state of a view.
   * @result current visibility state
   */
  ViewVisibility GetVisibility() const { return mVis; }

  /**
   * Get whether the view "floats" above all other views,
   * which tells the compositor not to consider higher views in
   * the view hierarchy that would geometrically intersect with
   * this view. This is a hack, but it fixes some problems with
   * views that need to be drawn in front of all other views.
   * @result true if the view floats, false otherwise.
   */
  bool GetFloating() const { return (mVFlags & NS_VIEW_FLAG_FLOATING) != 0; }

  /**
   * Called to query the parent of the view.
   * @result view's parent
   */
  nsView* GetParent() const { return mParent; }

  /**
   * The view's first child is the child which is earliest in document order.
   * @result first child
   */
  nsView* GetFirstChild() const { return mFirstChild; }

  /**
   * Called to query the next sibling of the view.
   * @result view's next sibling
   */
  nsView* GetNextSibling() const { return mNextSibling; }

  /**
   * Set the view's frame.
   */
  void SetFrame(nsIFrame* aRootFrame) { mFrame = aRootFrame; }

  /**
   * Retrieve the view's frame.
   */
  nsIFrame* GetFrame() const { return mFrame; }

  /**
   * Get the nearest widget in this view or a parent of this view and
   * the offset from the widget's origin to this view's origin
   * @param aOffset - if non-null the offset from this view's origin to the
   * widget's origin (usually positive) expressed in appunits of this will be
   * returned in aOffset.
   * @return the widget closest to this view; can be null because some view
   * trees don't have widgets at all (e.g., printing), but if any view in the
   * view tree has a widget, then it's safe to assume this will not return null
   */
  nsIWidget* GetNearestWidget(nsPoint* aOffset) const;

  /**
   * Create a widget to associate with this view.  This variant of
   * CreateWidget*() will look around in the view hierarchy for an
   * appropriate parent widget for the view.
   *
   * @param aWidgetInitData data used to initialize this view's widget before
   *        its create is called.
   * @return error status
   */
  nsresult CreateWidget(mozilla::widget::InitData* aWidgetInitData = nullptr,
                        bool aEnableDragDrop = true,
                        bool aResetVisibility = true);

  /**
   * Create a widget for this view with an explicit parent widget.
   * |aParentWidget| must be nonnull.  The other params are the same
   * as for |CreateWidget()|.
   */
  nsresult CreateWidgetForParent(nsIWidget* aParentWidget,
                                 mozilla::widget::InitData* = nullptr,
                                 bool aEnableDragDrop = true,
                                 bool aResetVisibility = true);

  /**
   * Create a popup widget for this view.  Pass |aParentWidget| to
   * explicitly set the popup's parent.  If it's not passed, the view
   * hierarchy will be searched for an appropriate parent widget.  The
   * other params are the same as for |CreateWidget()|, except that
   * |aWidgetInitData| must be nonnull.
   */
  nsresult CreateWidgetForPopup(mozilla::widget::InitData*,
                                nsIWidget* aParentWidget = nullptr);

  /**
   * Destroys the associated widget for this view.  If this method is
   * not called explicitly, the widget when be destroyed when its
   * view gets destroyed.
   */
  void DestroyWidget();

  /**
   * Attach/detach a top level widget from this view. When attached, the view
   * updates the widget's device context and allows the view to begin receiving
   * gecko events. The underlying base window associated with the widget will
   * continues to receive events it expects.
   *
   * An attached widget will not be destroyed when the view is destroyed,
   * allowing the recycling of a single top level widget over multiple views.
   *
   * @param aWidget The widget to attach to / detach from.
   */
  nsresult AttachToTopLevelWidget(nsIWidget* aWidget);
  nsresult DetachFromTopLevelWidget();

  /**
   * Returns a flag indicating whether the view owns it's widget
   * or is attached to an existing top level widget.
   */
  bool IsAttachedToTopLevel() const { return mWidgetIsTopLevel; }

  /**
   * In 4.0, the "cutout" nature of a view is queryable.
   * If we believe that all cutout view have a native widget, this
   * could be a replacement.
   * @param aWidget out parameter for widget that this view contains,
   *        or nullptr if there is none.
   */
  nsIWidget* GetWidget() const { return mWindow; }

  /**
   * The widget which we have attached a listener to can also have a "previous"
   * listener set on it. This is to keep track of the last nsView when
   * navigating to a new one so that we can continue to paint that if the new
   * one isn't ready yet.
   */
  void SetPreviousWidget(nsIWidget* aWidget) { mPreviousWindow = aWidget; }

  /**
   * Returns true if the view has a widget associated with it.
   */
  bool HasWidget() const { return mWindow != nullptr; }

  void SetForcedRepaint(bool aForceRepaint) { mForcedRepaint = aForceRepaint; }

  void SetNeedsWindowPropertiesSync();

  /**
   * Make aWidget direct its events to this view.
   * The caller must call DetachWidgetEventHandler before this view
   * is destroyed.
   */
  void AttachWidgetEventHandler(nsIWidget* aWidget);
  /**
   * Stop aWidget directing its events to this view.
   */
  void DetachWidgetEventHandler(nsIWidget* aWidget);

#ifdef DEBUG
  /**
   * Output debug info to FILE
   * @param out output file handle
   * @param aIndent indentation depth
   * NOTE: virtual so that debugging tools not linked into gklayout can access
   * it
   */
  virtual void List(FILE* out, int32_t aIndent = 0) const;
#endif  // DEBUG

  /**
   * @result true iff this is the root view for its view manager
   */
  bool IsRoot() const;

  LayoutDeviceIntRect CalcWidgetBounds(mozilla::widget::WindowType,
                                       mozilla::widget::TransparencyMode);

  LayoutDeviceIntRect RecalcWidgetBounds();

  // This is an app unit offset to add when converting view coordinates to
  // widget coordinates.  It is the offset in view coordinates from widget
  // origin (unlike views, widgets can't extend above or to the left of their
  // origin) to view origin expressed in appunits of this.
  nsPoint ViewToWidgetOffset() const { return mViewToWidgetOffset; }

  /**
   * Called to indicate that the position of the view has been changed.
   * The specified coordinates are in the parent view's coordinate space.
   * @param x new x position
   * @param y new y position
   */
  void SetPosition(nscoord aX, nscoord aY);

  /**
   * Called to indicate that the z-index of a view has been changed.
   * The z-index is relative to all siblings of the view.
   * @param aAuto Indicate that the z-index of a view is "auto". An "auto"
   *              z-index means that the view does not define a new stacking
   *              context, which means that the z-indicies of the view's
   *              children are relative to the view's siblings.
   * @param zindex new z depth
   */
  void SetZIndex(bool aAuto, int32_t aZIndex);
  bool GetZIndexIsAuto() const {
    return (mVFlags & NS_VIEW_FLAG_AUTO_ZINDEX) != 0;
  }
  int32_t GetZIndex() const { return mZIndex; }

  void SetParent(nsView* aParent) { mParent = aParent; }
  void SetNextSibling(nsView* aSibling) {
    NS_ASSERTION(aSibling != this, "Can't be our own sibling!");
    mNextSibling = aSibling;
  }

  nsRegion& GetDirtyRegion() {
    if (!mDirtyRegion) {
      NS_ASSERTION(!mParent || GetFloating(),
                   "Only display roots should have dirty regions");
      mDirtyRegion = mozilla::MakeUnique<nsRegion>();
    }
    return *mDirtyRegion;
  }

  // nsIWidgetListener
  virtual mozilla::PresShell* GetPresShell() override;
  virtual nsView* GetView() override { return this; }
  virtual bool WindowMoved(nsIWidget* aWidget, int32_t x, int32_t y,
                           ByMoveToRect) override;
  virtual bool WindowResized(nsIWidget* aWidget, int32_t aWidth,
                             int32_t aHeight) override;
#if defined(MOZ_WIDGET_ANDROID)
  virtual void DynamicToolbarMaxHeightChanged(
      mozilla::ScreenIntCoord aHeight) override;
  virtual void DynamicToolbarOffsetChanged(
      mozilla::ScreenIntCoord aOffset) override;
#endif
  virtual bool RequestWindowClose(nsIWidget* aWidget) override;
  MOZ_CAN_RUN_SCRIPT_BOUNDARY
  virtual void WillPaintWindow(nsIWidget* aWidget) override;
  MOZ_CAN_RUN_SCRIPT_BOUNDARY
  virtual bool PaintWindow(nsIWidget* aWidget,
                           LayoutDeviceIntRegion aRegion) override;
  MOZ_CAN_RUN_SCRIPT_BOUNDARY
  virtual void DidPaintWindow() override;
  virtual void DidCompositeWindow(
      mozilla::layers::TransactionId aTransactionId,
      const mozilla::TimeStamp& aCompositeStart,
      const mozilla::TimeStamp& aCompositeEnd) override;
  virtual void RequestRepaint() override;
  virtual bool ShouldNotBeVisible() override;
  MOZ_CAN_RUN_SCRIPT_BOUNDARY
  virtual nsEventStatus HandleEvent(mozilla::WidgetGUIEvent* aEvent,
                                    bool aUseAttachedEvents) override;
  virtual void SafeAreaInsetsChanged(const mozilla::ScreenIntMargin&) override;

  virtual ~nsView();

  nsPoint GetOffsetTo(const nsView* aOther, const int32_t aAPD) const;
  nsIWidget* GetNearestWidget(nsPoint* aOffset, const int32_t aAPD) const;

  bool IsPrimaryFramePaintSuppressed();

 private:
  explicit nsView(nsViewManager* = nullptr,
                  ViewVisibility = ViewVisibility::Show);

  bool ForcedRepaint() { return mForcedRepaint; }

  // Do the actual work of ResetWidgetBounds, unconditionally.  Don't
  // call this method if we have no widget.
  void DoResetWidgetBounds(bool aMoveOnly, bool aInvalidateChangedSize);
  void InitializeWindow(bool aEnableDragDrop, bool aResetVisibility);

  bool IsEffectivelyVisible();

  /**
   * Called to indicate that the dimensions of the view have been changed.
   * The x and y coordinates may be < 0, indicating that the view extends above
   * or to the left of its origin position. The term 'dimensions' indicates it
   * is relative to this view.
   */
  void SetDimensions(const nsRect& aRect, bool aPaint = true,
                     bool aResizeWidget = true);

  /**
   * Called to indicate that the visibility of a view has been
   * changed.
   * @param visibility new visibility state
   */
  void SetVisibility(ViewVisibility visibility);

  /**
   * Set/Get whether the view "floats" above all other views,
   * which tells the compositor not to consider higher views in
   * the view hierarchy that would geometrically intersect with
   * this view. This is a hack, but it fixes some problems with
   * views that need to be drawn in front of all other views.
   * @result true if the view floats, false otherwise.
   */
  void SetFloating(bool aFloatingView);

  // Helper function to get mouse grabbing off this view (by moving it to the
  // parent, if we can)
  void DropMouseGrabbing();

  // Same as GetBounds but converts to parent appunits if they are different.
  nsRect GetBoundsInParentUnits() const;

  bool HasNonEmptyDirtyRegion() {
    return mDirtyRegion && !mDirtyRegion->IsEmpty();
  }

  void InsertChild(nsView* aChild, nsView* aSibling);
  void RemoveChild(nsView* aChild);

  void ResetWidgetBounds(bool aRecurse, bool aForceSync);
  void AssertNoWindow();

  void NotifyEffectiveVisibilityChanged(bool aEffectivelyVisible);

  // Update the cached RootViewManager for all view manager descendents.
  void InvalidateHierarchy();

  nsViewManager* mViewManager;
  nsView* mParent;
  nsCOMPtr<nsIWidget> mWindow;
  nsCOMPtr<nsIWidget> mPreviousWindow;
  nsView* mNextSibling;
  nsView* mFirstChild;
  nsIFrame* mFrame;
  mozilla::UniquePtr<nsRegion> mDirtyRegion;
  int32_t mZIndex;
  ViewVisibility mVis;
  // position relative our parent view origin but in our appunits
  nscoord mPosX, mPosY;
  // relative to parent, but in our appunits
  nsRect mDimBounds;
  // in our appunits
  nsPoint mViewToWidgetOffset;
  uint32_t mVFlags;
  bool mWidgetIsTopLevel;
  bool mForcedRepaint;
  bool mNeedsWindowPropertiesSync;
};

#endif