/* -*- Mode: C++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#ifndef nsIWidget_h__
#define nsIWidget_h__

#include "nsISupports.h"
#include "nsColor.h"
#include "nsCoord.h"
#include "nsRect.h"
#include "nsPoint.h"

#include "prthread.h"
#include "nsEvent.h"
#include "nsCOMPtr.h"
#include "nsITheme.h"
#include "nsNativeWidget.h"
#include "nsWidgetInitData.h"
#include "nsTArray.h"

// forward declarations
class   nsIAppShell;
class   nsIToolkit;
class   nsIFontMetrics;
class   nsIRenderingContext;
class   nsIDeviceContext;
struct  nsFont;
class   nsIRollupListener;
class   nsGUIEvent;
class   imgIContainer;
class   gfxASurface;
class   nsIContent;

/**
 * Callback function that processes events.
 *
 * The argument is actually a subtype (subclass) of nsEvent which carries
 * platform specific information about the event. Platform specific code
 * knows how to deal with it.
 *
 * The return value determines whether or not the default action should take
 * place.
 */
typedef nsEventStatus (* EVENT_CALLBACK)(nsGUIEvent *event);

/**
 * Flags for the getNativeData function.
 * See getNativeData()
 */
#define NS_NATIVE_WINDOW      0
#define NS_NATIVE_GRAPHIC     1
#define NS_NATIVE_WIDGET      3
#define NS_NATIVE_DISPLAY     4
#define NS_NATIVE_REGION      5
#define NS_NATIVE_OFFSETX     6
#define NS_NATIVE_OFFSETY     7
#define NS_NATIVE_PLUGIN_PORT 8
#define NS_NATIVE_SCREEN      9
#define NS_NATIVE_SHELLWIDGET 10      // Get the shell GtkWidget
#ifdef XP_MACOSX
#define NS_NATIVE_PLUGIN_PORT_QD    100
#define NS_NATIVE_PLUGIN_PORT_CG    101
#endif
#ifdef XP_WIN
#define NS_NATIVE_TSF_THREAD_MGR       100
#define NS_NATIVE_TSF_CATEGORY_MGR     101
#define NS_NATIVE_TSF_DISPLAY_ATTR_MGR 102
#endif

#define NS_IWIDGET_IID \
{ 0x6bdb96ba, 0x1727, 0x40ae, \
  { 0x85, 0x55, 0x9c, 0x53, 0x4b, 0x95, 0x23, 0x98 } }

/*
 * Window shadow styles
 * Also used for the -moz-window-shadow CSS property
 */

#define NS_STYLE_WINDOW_SHADOW_NONE             0
#define NS_STYLE_WINDOW_SHADOW_DEFAULT          1

/**
 * Cursor types.
 */

enum nsCursor {   ///(normal cursor,       usually rendered as an arrow)
                eCursor_standard, 
                  ///(system is busy,      usually rendered as a hourglass or watch)
                eCursor_wait, 
                  ///(Selecting something, usually rendered as an IBeam)
                eCursor_select, 
                  ///(can hyper-link,      usually rendered as a human hand)
                eCursor_hyperlink, 
                  ///(north/south/west/east edge sizing)
                eCursor_n_resize,
                eCursor_s_resize,
                eCursor_w_resize,
                eCursor_e_resize,
                  ///(corner sizing)
                eCursor_nw_resize,
                eCursor_se_resize,
                eCursor_ne_resize,
                eCursor_sw_resize,
                eCursor_crosshair,
                eCursor_move,
                eCursor_help,
                eCursor_copy, // CSS3
                eCursor_alias,
                eCursor_context_menu,
                eCursor_cell,
                eCursor_grab,
                eCursor_grabbing,
                eCursor_spinning,
                eCursor_zoom_in,
                eCursor_zoom_out,
                eCursor_not_allowed,
                eCursor_col_resize,
                eCursor_row_resize,
                eCursor_no_drop,
                eCursor_vertical_text,
                eCursor_all_scroll,
                eCursor_nesw_resize,
                eCursor_nwse_resize,
                eCursor_ns_resize,
                eCursor_ew_resize,
                eCursor_none,
                // This one better be the last one in this list.
                eCursorCount
                }; 

enum nsTopLevelWidgetZPlacement { // for PlaceBehind()
  eZPlacementBottom = 0,  // bottom of the window stack
  eZPlacementBelow,       // just below another widget
  eZPlacementTop          // top of the window stack
};


/**
 * The base class for all the widgets. It provides the interface for
 * all basic and necessary functionality.
 */
class nsIWidget : public nsISupports {

  public:

    NS_DECLARE_STATIC_IID_ACCESSOR(NS_IWIDGET_IID)

    nsIWidget()
      : mLastChild(nsnull)
      , mPrevSibling(nsnull)
    {}

        
    /**
     * Create and initialize a widget. 
     *
     * All the arguments can be NULL in which case a top level window
     * with size 0 is created. The event callback function has to be
     * provided only if the caller wants to deal with the events this
     * widget receives.  The event callback is basically a preprocess
     * hook called synchronously. The return value determines whether
     * the event goes to the default window procedure or it is hidden
     * to the os. The assumption is that if the event handler returns
     * false the widget does not see the event. The widget should not 
     * automatically clear the window to the background color. The 
     * calling code must handle paint messages and clear the background 
     * itself. 
     *
     * In practice at least one of aParent and aNativeParent will be null. If
     * both are null the widget isn't parented (e.g. context menus or
     * independent top level windows).
     *
     * @param     aParent       parent nsIWidget
     * @param     aNativeParent native parent widget
     * @param     aRect         the widget dimension
     * @param     aHandleEventFunction the event handler callback function
     * @param     aContext
     * @param     aAppShell     the parent application shell. If nsnull,
     *                          the parent window's application shell will be used.
     * @param     aToolkit
     * @param     aInitData     data that is used for widget initialization
     *
     */
    NS_IMETHOD Create(nsIWidget        *aParent,
                      nsNativeWidget   aNativeParent,
                      const nsIntRect  &aRect,
                      EVENT_CALLBACK   aHandleEventFunction,
                      nsIDeviceContext *aContext,
                      nsIAppShell      *aAppShell = nsnull,
                      nsIToolkit       *aToolkit = nsnull,
                      nsWidgetInitData *aInitData = nsnull) = 0;

    /**
     * Accessor functions to get and set the client data associated with the
     * widget.
     */
    //@{
    NS_IMETHOD  GetClientData(void*& aClientData) = 0;
    NS_IMETHOD  SetClientData(void* aClientData) = 0;
    //@}

    /**
     * Close and destroy the internal native window. 
     * This method does not delete the widget.
     */

    NS_IMETHOD Destroy(void) = 0;


    /**
     * Reparent a widget
     *
     * Change the widgets parent
     *
     * @param     aNewParent   new parent 
     */
    NS_IMETHOD SetParent(nsIWidget* aNewParent) = 0;


    /**
     * Return the parent Widget of this Widget or nsnull if this is a 
     * top level window
     *
     * @return the parent widget or nsnull if it does not have a parent
     *
     */
    virtual nsIWidget* GetParent(void) = 0;

    /**
     * Return the top level Widget of this Widget
     *
     * @return the top level widget
     */
    virtual nsIWidget* GetTopLevelWidget() = 0;

    /**
     * Return the top (non-sheet) parent of this Widget if it's a sheet,
     * or nsnull if this isn't a sheet (or some other error occurred).
     * Sheets are only supported on some platforms (currently only OS X).
     *
     * @return the top (non-sheet) parent widget or nsnull
     *
     */
    virtual nsIWidget* GetSheetWindowParent(void) = 0;

    /**
     * Return the first child of this widget.  Will return null if
     * there are no children.
     */
    nsIWidget* GetFirstChild() const {
        return mFirstChild;
    }
    
    /**
     * Return the last child of this widget.  Will return null if
     * there are no children.
     */
    nsIWidget* GetLastChild() const {
        return mLastChild;
    }

    /**
     * Return the next sibling of this widget
     */
    nsIWidget* GetNextSibling() const {
        return mNextSibling;
    }
    
    /**
     * Set the next sibling of this widget
     */
    void SetNextSibling(nsIWidget* aSibling) {
        mNextSibling = aSibling;
    }
    
    /**
     * Return the previous sibling of this widget
     */
    nsIWidget* GetPrevSibling() const {
        return mPrevSibling;
    }

    /**
     * Set the previous sibling of this widget
     */
    void SetPrevSibling(nsIWidget* aSibling) {
        mPrevSibling = aSibling;
    }

    /**
     * Show or hide this widget
     *
     * @param aState PR_TRUE to show the Widget, PR_FALSE to hide it
     *
     */
    NS_IMETHOD Show(PRBool aState) = 0;

    /**
     * Make the window modal
     *
     */
    NS_IMETHOD SetModal(PRBool aModal) = 0;

    /**
     * Returns whether the window is visible
     *
     */
    NS_IMETHOD IsVisible(PRBool & aState) = 0;

    /**
     * Perform platform-dependent sanity check on a potential window position.
     * This is guaranteed to work only for top-level windows.
     *
     * @param aAllowSlop: if true, allow the window to slop offscreen;
     *                    the window should be partially visible. if false,
     *                    force the entire window onscreen (or at least
     *                    the upper-left corner, if it's too large).
     * @param aX in: an x position expressed in screen coordinates.
     *           out: the x position constrained to fit on the screen(s).
     * @param aY in: an y position expressed in screen coordinates.
     *           out: the y position constrained to fit on the screen(s).
     * @return vapid success indication. but see also the parameters.
     *
     **/
    NS_IMETHOD ConstrainPosition(PRBool aAllowSlop,
                                 PRInt32 *aX,
                                 PRInt32 *aY) = 0;

    /**
     * Move this widget.
     *
     * @param aX the new x position expressed in the parent's coordinate system
     * @param aY the new y position expressed in the parent's coordinate system
     *
     **/
    NS_IMETHOD Move(PRInt32 aX, PRInt32 aY) = 0;

    /**
     * Resize this widget. 
     *
     * @param aWidth  the new width expressed in the parent's coordinate system
     * @param aHeight the new height expressed in the parent's coordinate system
     * @param aRepaint whether the widget should be repainted
     *
     */
    NS_IMETHOD Resize(PRInt32 aWidth,
                      PRInt32 aHeight,
                      PRBool   aRepaint) = 0;

    /**
     * Move or resize this widget.
     *
     * @param aX       the new x position expressed in the parent's coordinate system
     * @param aY       the new y position expressed in the parent's coordinate system
     * @param aWidth   the new width expressed in the parent's coordinate system
     * @param aHeight  the new height expressed in the parent's coordinate system
     * @param aRepaint whether the widget should be repainted if the size changes
     *
     */
    NS_IMETHOD Resize(PRInt32 aX,
                      PRInt32 aY,
                      PRInt32 aWidth,
                      PRInt32 aHeight,
                      PRBool   aRepaint) = 0;

    /**
     * Sets the widget's z-index.
     */
    NS_IMETHOD SetZIndex(PRInt32 aZIndex) = 0;

    /**
     * Gets the widget's z-index. 
     */
    NS_IMETHOD GetZIndex(PRInt32* aZIndex) = 0;

    /**
     * Position this widget just behind the given widget. (Used to
     * control z-order for top-level widgets. Get/SetZIndex by contrast
     * control z-order for child widgets of other widgets.)
     * @param aPlacement top, bottom, or below a widget
     *                   (if top or bottom, param aWidget is ignored)
     * @param aWidget    widget to place this widget behind
     *                   (only if aPlacement is eZPlacementBelow).
     *                   null is equivalent to aPlacement of eZPlacementTop
     * @param aActivate  true to activate the widget after placing it
     */
    NS_IMETHOD PlaceBehind(nsTopLevelWidgetZPlacement aPlacement,
                           nsIWidget *aWidget, PRBool aActivate) = 0;

    /**
     * Minimize, maximize or normalize the window size.
     * Takes a value from nsSizeMode (see nsGUIEvent.h)
     */
    NS_IMETHOD SetSizeMode(PRInt32 aMode) = 0;

    /**
     * Return size mode (minimized, maximized, normalized).
     * Returns a value from nsSizeMode (see nsGUIEvent.h)
     */
    NS_IMETHOD GetSizeMode(PRInt32* aMode) = 0;

    /**
     * Enable or disable this Widget
     *
     * @param aState PR_TRUE to enable the Widget, PR_FALSE to disable it.
     *
     */
    NS_IMETHOD Enable(PRBool aState) = 0;

    /**
     * Ask whether the widget is enabled
     * @param aState returns PR_TRUE if the widget is enabled
     */
    NS_IMETHOD IsEnabled(PRBool *aState) = 0;

    /**
     * Give focus to this widget.
     */
    NS_IMETHOD SetFocus(PRBool aRaise = PR_FALSE) = 0;

    /**
     * Get this widget's outside dimensions relative to its parent widget
     *
     * @param aRect on return it holds the  x, y, width and height of this widget
     *
     */
    NS_IMETHOD GetBounds(nsIntRect &aRect) = 0;


    /**
     * Get this widget's outside dimensions in global coordinates. (One might think this
     * could be accomplished by stringing together other methods in this interface, but
     * then one would bloody one's nose on different coordinate system handling by different
     * platforms.) This includes any title bar on the window.
     *
     *
     * @param aRect on return it holds the  x, y, width and height of this widget
     *
     */
    NS_IMETHOD GetScreenBounds(nsIntRect &aRect) = 0;


    /**
     * Get this widget's client area dimensions, if the window has a 3D border appearance
     * this returns the area inside the border, The x and y are always zero
     *
     * @param aRect on return it holds the  x. y, width and height of the client area of this widget
     *
     */
    NS_IMETHOD GetClientBounds(nsIntRect &aRect) = 0;

    /**
     * Get the foreground color for this widget
     *
     * @return this widget's foreground color
     *
     */
    virtual nscolor GetForegroundColor(void) = 0;

    /**
     * Set the foreground color for this widget
     *
     * @param aColor the new foreground color
     *
     */

    NS_IMETHOD SetForegroundColor(const nscolor &aColor) = 0;

    /**
     * Get the background color for this widget
     *
     * @return this widget's background color
     *
     */

    virtual nscolor GetBackgroundColor(void) = 0;

    /**
     * Set the background color for this widget
     *
     * @param aColor the new background color
     *
     */

    NS_IMETHOD SetBackgroundColor(const nscolor &aColor) = 0;

    /**
     * Get the cursor for this widget.
     *
     * @return this widget's cursor.
     */

    virtual nsCursor GetCursor(void) = 0;

    /**
     * Set the cursor for this widget
     *
     * @param aCursor the new cursor for this widget
     */

    NS_IMETHOD SetCursor(nsCursor aCursor) = 0;

    /**
     * Sets an image as the cursor for this widget.
     *
     * @param aCursor the cursor to set
     * @param aX the X coordinate of the hotspot (from left).
     * @param aY the Y coordinate of the hotspot (from top).
     * @retval NS_ERROR_NOT_IMPLEMENTED if setting images as cursors is not
     *         supported
     */
    NS_IMETHOD SetCursor(imgIContainer* aCursor,
                         PRUint32 aHotspotX, PRUint32 aHotspotY) = 0;

    /** 
     * Get the window type of this widget
     *
     * @param aWindowType the window type of the widget
     */
    NS_IMETHOD GetWindowType(nsWindowType& aWindowType) = 0;

    /**
     * Set the transparency mode of the top-level window containing this widget.
     * So, e.g., if you call this on the widget for an IFRAME, the top level
     * browser window containing the IFRAME actually gets set. Be careful.
     *
     * This can fail if the platform doesn't support
     * transparency/glass. By default widgets are not
     * transparent.  This will also fail if the toplevel window is not
     * a Mozilla window, e.g., if the widget is in an embedded
     * context.
     *
     * After transparency/glass has been enabled, the initial alpha channel
     * value for all pixels is 1, i.e., opaque.
     * If the window is resized then the alpha channel values for
     * all pixels are reset to 1.
     * Pixel RGB color values are already premultiplied with alpha channel values.
     */
    virtual void SetTransparencyMode(nsTransparencyMode aMode) = 0;

    /**
     * Get the transparency mode of the top-level window that contains this
     * widget.
     */
    virtual nsTransparencyMode GetTransparencyMode() = 0;

    /**
     * This represents a command to set the bounds and clip region of
     * a child widget.
     */
    struct Configuration {
        nsIWidget* mChild;
        nsIntRect mBounds;
        nsTArray<nsIntRect> mClipRegion;
    };

    /**
     * Sets the clip region of each mChild (which must actually be a child
     * of this widget) to the union of the pixel rects given in
     * mClipRegion, all relative to the top-left of the child
     * widget. Clip regions are not implemented on all platforms and only
     * need to actually work for children that are plugins.
     * 
     * Also sets the bounds of each child to mBounds.
     * 
     * This will invalidate areas of the children that have changed, but
     * does not need to invalidate any part of this widget.
     */
    virtual nsresult ConfigureChildren(const nsTArray<Configuration>& aConfigurations) = 0;

    /**
     * Appends to aRects the rectangles constituting this widget's clip
     * region. If this widget is not clipped, appends a single rectangle
     * (0, 0, bounds.width, bounds.height).
     */
    virtual void GetWindowClipRegion(nsTArray<nsIntRect>* aRects) = 0;

    /**
     * Set the shadow style of the window.
     *
     * Ignored on child widgets and on non-Mac platforms.
     */
    NS_IMETHOD SetWindowShadowStyle(PRInt32 aStyle) = 0;

    /*
     * On Mac OS X, this method shows or hides the pill button in the titlebar
     * that's used to collapse the toolbar.
     *
     * Ignored on child widgets and on non-Mac platforms.
     */
    virtual void SetShowsToolbarButton(PRBool aShow) = 0;

    /** 
     * Hide window chrome (borders, buttons) for this widget.
     *
     */
    NS_IMETHOD HideWindowChrome(PRBool aShouldHide) = 0;

    /**
     * Put the toplevel window into or out of fullscreen mode.
     *
     */
    NS_IMETHOD MakeFullScreen(PRBool aFullScreen) = 0;

    /**
     * Invalidate a specified rect for a widget and repaints it.
     *
     * @param aIsSynchronouse PR_TRUE then repaint synchronously. If PR_FALSE repaint later.
     * @see #Update()
     */

    NS_IMETHOD Invalidate(const nsIntRect & aRect, PRBool aIsSynchronous) = 0;

    /**
     * Force a synchronous repaint of the window if there are dirty rects.
     *
     * @see Invalidate()
     */

     NS_IMETHOD Update() = 0;

    /**
     * Return the widget's toolkit
     *
     * An AddRef has NOT been done for the caller.
     *
     * @return the toolkit this widget was created in. See nsToolkit.
     */

    virtual nsIToolkit* GetToolkit() = 0;    

    /**
     * Scroll a set of rectangles in this widget and (as simultaneously as
     * possible) modify the specified child widgets.
     * 
     * This will invalidate areas of the children that have changed, unless
     * they have just moved by the scroll amount, but does not need to
     * invalidate any part of this widget, except where the scroll
     * operation fails to blit because part of the window is unavailable
     * (e.g. partially offscreen).
     * 
     * The caller guarantees that the rectangles in aDestRects are ordered
     * so that copying from aDestRects[i] - aDelta to aDestRects[i] does
     * not alter anything in aDestRects[j] - aDelta for j > i. That is,
     * it's safe to just copy the rectangles in the order given in
     * aDestRects.
     *
     * @param aDelta amount to scroll (device pixels)
     * @param aDestRects rectangles to copy into
     * (device pixels relative to this widget)
     * @param aReconfigureChildren commands to set the bounds and clip
     * region of a subset of the children of this widget; these should
     * be performed simultaneously with the scrolling, as far as possible,
     * to avoid visual artifacts.
     */
    virtual void Scroll(const nsIntPoint& aDelta,
                        const nsTArray<nsIntRect>& aDestRects,
                        const nsTArray<Configuration>& aReconfigureChildren) = 0;

    /** 
     * Internal methods
     */

    //@{
    virtual void AddChild(nsIWidget* aChild) = 0;
    virtual void RemoveChild(nsIWidget* aChild) = 0;
    virtual void* GetNativeData(PRUint32 aDataType) = 0;
    virtual void FreeNativeData(void * data, PRUint32 aDataType) = 0;//~~~
    virtual nsIRenderingContext* GetRenderingContext() = 0;

    // GetDeviceContext returns a weak pointer to this widget's device context
    virtual nsIDeviceContext* GetDeviceContext() = 0;

    //@}

    /**
     * Set the widget's title.
     * Must be called after Create.
     *
     * @param aTitle string displayed as the title of the widget
     */

    NS_IMETHOD SetTitle(const nsAString& aTitle) = 0;

    /**
     * Set the widget's icon.
     * Must be called after Create.
     *
     * @param anIconSpec string specifying the icon to use; convention is to pass
     *                   a resource: URL from which a platform-dependent resource
     *                   file name will be constructed
     */

    NS_IMETHOD SetIcon(const nsAString& anIconSpec) = 0;

    /**
     * Return this widget's origin in screen coordinates.
     *
     * @return screen coordinates stored in the x,y members
     */

    virtual nsIntPoint WidgetToScreenOffset() = 0;

    /**
     * Dispatches an event to the widget
     *
     */
    NS_IMETHOD DispatchEvent(nsGUIEvent* event, nsEventStatus & aStatus) = 0;

    /**
     * Enables the dropping of files to a widget (XXX this is temporary)
     *
     */
    NS_IMETHOD EnableDragDrop(PRBool aEnable) = 0;
   
    /**
     * Enables/Disables system mouse capture.
     * @param aCapture PR_TRUE enables mouse capture, PR_FALSE disables mouse capture 
     *
     */
    NS_IMETHOD CaptureMouse(PRBool aCapture) = 0;

    /**
     * Classify the window for the window manager. Mostly for X11.
     */
    NS_IMETHOD SetWindowClass(const nsAString& xulWinType) = 0;

    /**
     * Enables/Disables system capture of any and all events that would cause a
     * dropdown to be rolled up, This method ignores the aConsumeRollupEvent 
     * parameter when aDoCapture is FALSE
     * @param aDoCapture PR_TRUE enables capture, PR_FALSE disables capture 
     * @param aConsumeRollupEvent PR_TRUE consumes the rollup event, PR_FALSE dispatches rollup event
     *
     */
    NS_IMETHOD CaptureRollupEvents(nsIRollupListener * aListener, PRBool aDoCapture, PRBool aConsumeRollupEvent) = 0;

    /**
     * Bring this window to the user's attention.  This is intended to be a more
     * gentle notification than popping the window to the top or putting up an
     * alert.  See, for example, Win32 FlashWindow or the NotificationManager on
     * the Mac.  The notification should be suppressed if the window is already
     * in the foreground and should be dismissed when the user brings this window
     * to the foreground.
     * @param aCycleCount Maximum number of times to animate the window per system 
     *                    conventions. If set to -1, cycles indefinitely until 
     *                    window is brought into the foreground.
     */
    NS_IMETHOD GetAttention(PRInt32 aCycleCount) = 0;

    /**
     * Ask whether there user input events pending.  All input events are
     * included, including those not targeted at this nsIwidget instance.
     */
    virtual PRBool HasPendingInputEvent() = 0;

    /**
     * Called when when we need to begin secure keyboard input, such as when a password field
     * gets focus.
     *
     * NOTE: Calls to this method may not be nested and you can only enable secure keyboard input
     * for one widget at a time.
     */
    NS_IMETHOD BeginSecureKeyboardInput() = 0;

    /**
     * Called when when we need to end secure keyboard input, such as when a password field
     * loses focus.
     *
     * NOTE: Calls to this method may not be nested and you can only enable secure keyboard input
     * for one widget at a time.
     */
    NS_IMETHOD EndSecureKeyboardInput() = 0;

    /**
     * Set the background color of the window titlebar for this widget. On Mac,
     * for example, this will remove the grey gradient and bottom border and
     * instead show a single, solid color.
     *
     * Ignored on any platform that does not support it. Ignored by widgets that
     * do not represent windows.
     *
     * @param aColor  The color to set the title bar background to. Alpha values 
     *                other than fully transparent (0) are respected if possible  
     *                on the platform. An alpha of 0 will cause the window to 
     *                draw with the default style for the platform.
     *
     * @param aActive Whether the color should be applied to active or inactive
     *                windows.
     */
    NS_IMETHOD SetWindowTitlebarColor(nscolor aColor, PRBool aActive) = 0;

    /**
     * If set to true, the window will draw its contents into the titlebar
     * instead of below it.
     *
     * Ignored on any platform that does not support it. Ignored by widgets that
     * do not represent windows.
     * May result in a resize event, so should only be called from places where
     * reflow and painting is allowed.
     *
     * @param aState Whether drawing into the titlebar should be activated.
     */
    virtual void SetDrawsInTitlebar(PRBool aState) = 0;

    /*
     * Determine whether the widget shows a resize widget. If it does,
     * aResizerRect returns the resizer's rect.
     *
     * Returns false on any platform that does not support it.
     *
     * @param aResizerRect The resizer's rect in device pixels.
     * @return Whether a resize widget is shown.
     */
    virtual PRBool ShowsResizeIndicator(nsIntRect* aResizerRect) = 0;

    /**
     * Get the Thebes surface associated with this widget.
     */
    virtual gfxASurface *GetThebesSurface() = 0;

    /**
     * Return the popup that was last rolled up, or null if there isn't one.
     */
    virtual nsIContent* GetLastRollup() = 0;

    /**
     * Begin a window resizing drag, based on the event passed in.
     */
    NS_IMETHOD BeginResizeDrag(nsGUIEvent* aEvent, PRInt32 aHorizontal, PRInt32 aVertical) = 0;

    enum Modifiers {
        CAPS_LOCK = 0x01, // when CapsLock is active
        NUM_LOCK = 0x02, // when NumLock is active
        SHIFT_L = 0x0100,
        SHIFT_R = 0x0200,
        CTRL_L = 0x0400,
        CTRL_R = 0x0800,
        ALT_L = 0x1000, // includes Option
        ALT_R = 0x2000,
        COMMAND_L = 0x4000,
        COMMAND_R = 0x8000,
        HELP = 0x10000,
        FUNCTION = 0x100000,
        NUMERIC_KEY_PAD = 0x01000000 // when the key is coming from the keypad
    };
    /**
     * Utility method intended for testing. Dispatches native key events
     * to this widget to simulate the press and release of a key.
     * @param aNativeKeyboardLayout a *platform-specific* constant.
     * On Mac, this is the resource ID for a 'uchr' or 'kchr' resource.
     * On Windows, it is converted to a hex string and passed to
     * LoadKeyboardLayout, see
     * http://msdn.microsoft.com/en-us/library/ms646305(VS.85).aspx
     * @param aNativeKeyCode a *platform-specific* keycode.
     * On Windows, this is the virtual key code.
     * @param aModifiers some combination of the above 'Modifiers' flags;
     * not all flags will apply to all platforms. Mac ignores the _R
     * modifiers. Windows ignores COMMAND, NUMERIC_KEY_PAD, HELP and
     * FUNCTION.
     * @param aCharacters characters that the OS would decide to generate
     * from the event. On Windows, this is the charCode passed by
     * WM_CHAR.
     * @param aUnmodifiedCharacters characters that the OS would decide
     * to generate from the event if modifier keys (other than shift)
     * were assumed inactive. Needed on Mac, ignored on Windows.
     * @return NS_ERROR_NOT_AVAILABLE to indicate that the keyboard
     * layout is not supported and the event was not fired
     */
    virtual nsresult SynthesizeNativeKeyEvent(PRInt32 aNativeKeyboardLayout,
                                              PRInt32 aNativeKeyCode,
                                              PRUint32 aModifierFlags,
                                              const nsAString& aCharacters,
                                              const nsAString& aUnmodifiedCharacters) = 0;

    /**
     * Utility method intended for testing. Dispatches native mouse events
     * may even move the mouse cursor. On Mac the events are guaranteed to
     * be sent to the window containing this widget, but on Windows they'll go
     * to whatever's topmost on the screen at that position, so for
     * cross-platform testing ensure that your window is at the top of the
     * z-order.
     * @param aPoint screen location of the mouse, in device
     * pixels, with origin at the top left
     * @param aNativeMessage *platform-specific* event type (e.g. on Mac,
     * NSMouseMoved; on Windows, MOUSEEVENTF_MOVE, MOUSEEVENTF_LEFTDOWN etc)
     * @param aModifierFlags *platform-specific* modifier flags (ignored
     * on Windows)
     */
    virtual nsresult SynthesizeNativeMouseEvent(nsIntPoint aPoint,
                                                PRUint32 aNativeMessage,
                                                PRUint32 aModifierFlags) = 0;

    /**
     * Activates a native menu item at the position specified by the index
     * string. The index string is a string of positive integers separated
     * by the "|" (pipe) character. The last integer in the string represents
     * the item index in a submenu located using the integers preceeding it.
     *
     * Example: 1|0|4
     * In this string, the first integer represents the top-level submenu
     * in the native menu bar. Since the integer is 1, it is the second submeu
     * in the native menu bar. Within that, the first item (index 0) is a
     * submenu, and we want to activate the 5th item within that submenu.
     */
    virtual nsresult ActivateNativeMenuItemAt(const nsAString& indexString) = 0;

    /**
     * This is used for native menu system testing.
     *
     * Updates a native menu at the position specified by the index string.
     * The index string is a string of positive integers separated by the "|" 
     * (pipe) character.
     *
     * Example: 1|0|4
     * In this string, the first integer represents the top-level submenu
     * in the native menu bar. Since the integer is 1, it is the second submeu
     * in the native menu bar. Within that, the first item (index 0) is a
     * submenu, and we want to update submenu at index 4 within that submenu.
     *
     * If this is called with an empty string it forces a full reload of the
     * menu system.
     */
    virtual nsresult ForceUpdateNativeMenuAt(const nsAString& indexString) = 0;

    /*
     * Force Input Method Editor to commit the uncommitted input
     */
    NS_IMETHOD ResetInputState()=0;

    /*
     * Following methods relates to IME 'Opened'/'Closed' state.
     * 'Opened' means the user can input any character. I.e., users can input Japanese  
     * and other characters. The user can change the state to 'Closed'.
     * 'Closed' means the user can input ASCII characters only. This is the same as a
     * non-IME environment. The user can change the state to 'Opened'.
     * For more information is here.
     * http://bugzilla.mozilla.org/show_bug.cgi?id=16940#c48
     */

    /*
     * Set the state to 'Opened' or 'Closed'.
     * If aState is TRUE, IME open state is set to 'Opened'.
     * If aState is FALSE, set to 'Closed'.
     */
    NS_IMETHOD SetIMEOpenState(PRBool aState) = 0;

    /*
     * Get IME is 'Opened' or 'Closed'.
     * If IME is 'Opened', aState is set PR_TRUE.
     * If IME is 'Closed', aState is set PR_FALSE.
     */
    NS_IMETHOD GetIMEOpenState(PRBool* aState) = 0;

    /*
     * IME enabled states, the aState value of SetIMEEnabled/GetIMEEnabled
     * should be one value of following values.
     *
     * WARNING: If you change these values, you also need to edit:
     *   nsIDOMWindowUtils.idl
     *   nsDOMWindowUtils::SetIMEEnabled
     *   nsContentUtils::GetWidgetStatusFromIMEStatus
     */
    enum IMEStatus {
      /*
       * 'Disabled' means the user cannot use IME. So, the open state should be
       * 'closed' during 'disabled'.
       */
      IME_STATUS_DISABLED = 0,
      /*
       * 'Enabled' means the user can use IME.
       */
      IME_STATUS_ENABLED = 1,
      /*
       * 'Password' state is a special case for the password editors.
       * E.g., on mac, the password editors should disable the non-Roman
       * keyboard layouts at getting focus. Thus, the password editor may have
       * special rules on some platforms.
       */
      IME_STATUS_PASSWORD = 2,
      /*
       * This state is used when a plugin is focused.
       * When a plug-in is focused content, we should send native events
       * directly. Because we don't process some native events, but they may
       * be needed by the plug-in.
       */
      IME_STATUS_PLUGIN = 3
    };

    /*
     * Set the state to 'Enabled' or 'Disabled' or 'Password'.
     */
    NS_IMETHOD SetIMEEnabled(PRUint32 aState) = 0;

    /*
     * Get IME is 'Enabled' or 'Disabled' or 'Password'.
     */
    NS_IMETHOD GetIMEEnabled(PRUint32* aState) = 0;

    /*
     * Destruct and don't commit the IME composition string.
     */
    NS_IMETHOD CancelIMEComposition() = 0;

    /*
     * Get toggled key states.
     * aKeyCode should be NS_VK_CAPS_LOCK or  NS_VK_NUM_LOCK or
     * NS_VK_SCROLL_LOCK.
     * aLEDState is the result for current LED state of the key.
     * If the LED is 'ON', it returns TRUE, otherwise, FALSE.
     * If the platform doesn't support the LED state (or we cannot get the
     * state), this method returns NS_ERROR_NOT_IMPLEMENTED.
     */
    NS_IMETHOD GetToggledKeyState(PRUint32 aKeyCode, PRBool* aLEDState) = 0;

    /*
     * An editable node (i.e. input/textarea/design mode document)
     *  is receiving or giving up focus
     * aFocus is true if node is receiving focus
     * aFocus is false if node is giving up focus (blur)
     *
     * If this returns NS_ERROR_*, OnIMETextChange and OnIMESelectionChange
     * and OnIMEFocusChange(PR_FALSE) will be never called.
     */
    NS_IMETHOD OnIMEFocusChange(PRBool aFocus) = 0;

    /*
     * Text content of the focused node has changed
     * aStart is the starting offset of the change
     * aOldEnd is the ending offset of the change
     * aNewEnd is the caret offset after the change
     */
    NS_IMETHOD OnIMETextChange(PRUint32 aStart,
                               PRUint32 aOldEnd,
                               PRUint32 aNewEnd) = 0;

    /*
     * Selection has changed in the focused node
     */
    NS_IMETHOD OnIMESelectionChange(void) = 0;

    /*
     * Call this method when a dialog is opened which has a default button.
     * The button's rectangle should be supplied in aButtonRect.
     */ 
    NS_IMETHOD OnDefaultButtonLoaded(const nsIntRect &aButtonRect) = 0;

    /**
     * Compute the overridden system mouse scroll speed on the root content of
     * web pages.  The widget may set the same value as aOriginalDelta.  E.g.,
     * when the system scrolling settings were customized, widget can respect
     * the will of the user.
     *
     * This is called only when the mouse wheel event scrolls the root content
     * of the web pages by line.  In other words, this isn't called when the
     * mouse wheel event is used for zoom, page scroll and other special
     * actions.  And also this isn't called when the user doesn't use the
     * system wheel speed settings.
     *
     * @param aOriginalDelta   The delta value of the current mouse wheel
     *                         scrolling event.
     * @param aIsHorizontal    If TRUE, the scrolling direction is horizontal.
     *                         Otherwise, it's vertical.
     * @param aOverriddenDelta The overridden mouse scrolling speed.  This value
     *                         may be same as aOriginalDelta.
     */
    NS_IMETHOD OverrideSystemMouseScrollSpeed(PRInt32 aOriginalDelta,
                                              PRBool aIsHorizontal,
                                              PRInt32 &aOverriddenDelta) = 0;

protected:
    // keep the list of children.  We also keep track of our siblings.
    // The ownership model is as follows: parent holds a strong ref to
    // the first element of the list, and each element holds a strong
    // ref to the next element in the list.  The prevsibling and
    // lastchild pointers are weak, which is fine as long as they are
    // maintained properly.
    nsCOMPtr<nsIWidget> mFirstChild;
    nsIWidget* mLastChild;
    nsCOMPtr<nsIWidget> mNextSibling;
    nsIWidget* mPrevSibling;
};

NS_DEFINE_STATIC_IID_ACCESSOR(nsIWidget, NS_IWIDGET_IID)

#endif // nsIWidget_h__
