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 /* -*- 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/. */

 /* service providing platform-specific native rendering for widgets */

 #ifndef nsITheme_h_

 #define nsITheme_h_

 #include "nsISupports.h"

 #include "nsCOMPtr.h"

 #include "nsColor.h"

 struct nsRect;

 struct nsIntRect;

 struct nsIntSize;

 class nsIntRegion;

 struct nsFont;

 struct nsIntMargin;

 class nsPresContext;

 class nsRenderingContext;

 class nsDeviceContext;

 class nsIFrame;

 class nsIContent;

 class nsIAtom;

 class nsIWidget;

 // IID for the nsITheme interface

 // {b0f3efe9-0bd4-4f6b-8daa-0ec7f6006822}

  #define NS_ITHEME_IID     \

 { 0x4440b5c7, 0xd8bd, 0x4d9c, \

   { 0x9c, 0x3e, 0xa5, 0xe6, 0x26, 0x81, 0x10, 0xa0 } }

 // {D930E29B-6909-44e5-AB4B-AF10D6923705}

 #define NS_THEMERENDERER_CID \

 { 0x9020805b, 0x14a3, 0x4125, \

   { 0xa5, 0x63, 0x4a, 0x8c, 0x5d, 0xe0, 0xa9, 0xa3 } }

 /**

  * nsITheme is a service that provides platform-specific native

  * rendering for widgets.  In other words, it provides the necessary

  * operations to draw a rendering object (an nsIFrame) as a native

  * widget.

  *

  * All the methods on nsITheme take a rendering context or device

  * context, a frame (the rendering object), and a widget type (one of

  * the constants in nsThemeConstants.h).

  */

 class nsITheme: public nsISupports {

 public:

   NS_DECLARE_STATIC_IID_ACCESSOR(NS_ITHEME_IID)

   /**

    * Draw the actual theme background.

    * @param aContext the context to draw into

    * @param aFrame the frame for the widget that we're drawing

    * @param aWidgetType the -moz-appearance value to draw

    * @param aRect the rectangle defining the area occupied by the widget

    * @param aDirtyRect the rectangle that needs to be drawn

    */

   NS_IMETHOD DrawWidgetBackground(nsRenderingContext* aContext,

                                   nsIFrame* aFrame,

                                   uint8_t aWidgetType,

                                   const nsRect& aRect,

                                   const nsRect& aDirtyRect) = 0;

   /**

    * Get the computed CSS border for the widget, in pixels.

    */

   NS_IMETHOD GetWidgetBorder(nsDeviceContext* aContext, 

                              nsIFrame* aFrame,

                              uint8_t aWidgetType,

                              nsIntMargin* aResult)=0;

   /**

    * This method can return false to indicate that the CSS padding

    * value should be used.  Otherwise, it will fill in aResult with the

    * computed padding, in pixels, and return true.

    *

    * XXXldb This ought to be required to return true for non-containers

    * so that we don't let specified padding that has no effect change

    * the computed padding and potentially the size.

    */

   virtual bool GetWidgetPadding(nsDeviceContext* aContext,

                                   nsIFrame* aFrame,

                                   uint8_t aWidgetType,

                                   nsIntMargin* aResult) = 0;

   /**

    * On entry, *aResult is positioned at 0,0 and sized to the new size

    * of aFrame (aFrame->GetSize() may be stale and should not be used).

    * This method can return false to indicate that no special

    * overflow area is required by the native widget. Otherwise it will

    * fill in aResult with the desired overflow area, in appunits, relative

    * to the frame origin, and return true.

    *

    * This overflow area is used to determine what area needs to be

    * repainted when the widget changes.  However, it does not affect the

    * widget's size or what area is reachable by scrollbars.  (In other

    * words, in layout terms, it affects visual overflow but not

    * scrollable overflow.)

    */

   virtual bool GetWidgetOverflow(nsDeviceContext* aContext,

                                    nsIFrame* aFrame,

                                    uint8_t aWidgetType,

                                    /*INOUT*/ nsRect* aOverflowRect)

   { return false; }

   /**

    * Get the minimum border-box size of a widget, in *pixels* (in

    * |aResult|).  If |aIsOverridable| is set to true, this size is a

    * minimum size; if false, this size is the only valid size for the

    * widget.

    */

   NS_IMETHOD GetMinimumWidgetSize(nsRenderingContext* aContext,

                                   nsIFrame* aFrame,

                                   uint8_t aWidgetType,

                                   nsIntSize* aResult,

                                   bool* aIsOverridable)=0;

   enum Transparency {

     eOpaque = 0,

     eTransparent,

     eUnknownTransparency

   };

   /**

    * Returns what we know about the transparency of the widget.

    */

   virtual Transparency GetWidgetTransparency(nsIFrame* aFrame, uint8_t aWidgetType)

   { return eUnknownTransparency; }

   NS_IMETHOD WidgetStateChanged(nsIFrame* aFrame, uint8_t aWidgetType, 

                                 nsIAtom* aAttribute, bool* aShouldRepaint)=0;

   NS_IMETHOD ThemeChanged()=0;

   virtual bool WidgetAppearanceDependsOnWindowFocus(uint8_t aWidgetType)

   { return false; }

   /**

    * Can the nsITheme implementation handle this widget?

    */

   virtual bool ThemeSupportsWidget(nsPresContext* aPresContext,

                                      nsIFrame* aFrame,

                                      uint8_t aWidgetType)=0;

   virtual bool WidgetIsContainer(uint8_t aWidgetType)=0;

   /**

    * Does the nsITheme implementation draw its own focus ring for this widget?

    */

   virtual bool ThemeDrawsFocusForWidget(uint8_t aWidgetType)=0;

   /**

     * Should we insert a dropmarker inside of combobox button?

    */

   virtual bool ThemeNeedsComboboxDropmarker()=0;

   /**

    * Should we hide scrollbars?

    */

   virtual bool ShouldHideScrollbars()

   { return false; }

 };

 NS_DEFINE_STATIC_IID_ACCESSOR(nsITheme, NS_ITHEME_IID)

 // Creator function

 extern nsresult NS_NewNativeTheme(nsISupports *aOuter, REFNSIID aIID, void **aResult);

 #endif