gfx/src/nsITheme.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* service providing platform-specific native rendering for widgets */
   8
   9 #ifndef nsITheme_h_
  10 #define nsITheme_h_
  11
  12 #include "mozilla/AlreadyAddRefed.h"
  13 #include "nsISupports.h"
  14 #include "nsID.h"
  15 #include "nscore.h"
  16 #include "Units.h"
  17
  18 struct nsRect;
  19 class gfxContext;
  20 class nsAttrValue;
  21 class nsPresContext;
  22 class nsDeviceContext;
  23 class nsIFrame;
  24 class nsAtom;
  25 class nsIWidget;
  26
  27 namespace mozilla {
  28 class ComputedStyle;
  29 enum class StyleAppearance : uint8_t;
  30 enum class StyleScrollbarWidth : uint8_t;
  31 namespace layers {
  32 class StackingContextHelper;
  33 class RenderRootStateManager;
  34 }  // namespace layers
  35 namespace wr {
  36 class DisplayListBuilder;
  37 class IpcResourceUpdateQueue;
  38 }  // namespace wr
  39 }  // namespace mozilla
  40
  41 // IID for the nsITheme interface
  42 // {7329f760-08cb-450f-8225-dae729096dec}
  43 #define NS_ITHEME_IID                                \
  44   {                                                  \
  45     0x7329f760, 0x08cb, 0x450f, {                    \
  46       0x82, 0x25, 0xda, 0xe7, 0x29, 0x09, 0x6d, 0xec \
  47     }                                                \
  48   }
  49
  50 /**
  51  * nsITheme is a service that provides platform-specific native
  52  * rendering for widgets.  In other words, it provides the necessary
  53  * operations to draw a rendering object (an nsIFrame) as a native
  54  * widget.
  55  *
  56  * All the methods on nsITheme take a rendering context or device
  57  * context, a frame (the rendering object), and a widget type (one of
  58  * the constants in nsThemeConstants.h).
  59  */
  60 class nsITheme : public nsISupports {
  61  protected:
  62   using LayoutDeviceIntMargin = mozilla::LayoutDeviceIntMargin;
  63   using LayoutDeviceIntSize = mozilla::LayoutDeviceIntSize;
  64   using LayoutDeviceIntCoord = mozilla::LayoutDeviceIntCoord;
  65   using StyleAppearance = mozilla::StyleAppearance;
  66   using StyleScrollbarWidth = mozilla::StyleScrollbarWidth;
  67   using ComputedStyle = mozilla::ComputedStyle;
  68
  69  public:
  70   NS_DECLARE_STATIC_IID_ACCESSOR(NS_ITHEME_IID)
  71
  72   /**
  73    * Draw the actual theme background.
  74    * @param aContext the context to draw into
  75    * @param aFrame the frame for the widget that we're drawing
  76    * @param aWidgetType the -moz-appearance value to draw
  77    * @param aRect the rectangle defining the area occupied by the widget
  78    * @param aDirtyRect the rectangle that needs to be drawn
  79    * @param DrawOverflow whether outlines, shadows and other such overflowing
  80    *        things should be drawn. Honoring this creates better results for
  81    *        box-shadow, though it's not a hard requirement.
  82    */
  83   enum class DrawOverflow { No, Yes };
  84   NS_IMETHOD DrawWidgetBackground(gfxContext* aContext, nsIFrame* aFrame,
  85                                   StyleAppearance aWidgetType,
  86                                   const nsRect& aRect, const nsRect& aDirtyRect,
  87                                   DrawOverflow = DrawOverflow::Yes) = 0;
  88
  89   /**
  90    * Create WebRender commands for the theme background.
  91    * @return true if the theme knows how to create WebRender commands for the
  92    *         given widget type, false if DrawWidgetBackground need sto be called
  93    *         instead.
  94    */
  95   virtual bool CreateWebRenderCommandsForWidget(
  96       mozilla::wr::DisplayListBuilder& aBuilder,
  97       mozilla::wr::IpcResourceUpdateQueue& aResources,
  98       const mozilla::layers::StackingContextHelper& aSc,
  99       mozilla::layers::RenderRootStateManager* aManager, nsIFrame* aFrame,
 100       StyleAppearance aWidgetType, const nsRect& aRect) {
 101     return false;
 102   }
 103
 104   /**
 105    * Returns the minimum widths of a scrollbar for a given style, that is, the
 106    * minimum width for a vertical scrollbar, and the minimum height of a
 107    * horizontal scrollbar.
 108    */
 109   enum class Overlay { No, Yes };
 110   struct ScrollbarSizes {
 111     LayoutDeviceIntCoord mVertical;
 112     LayoutDeviceIntCoord mHorizontal;
 113   };
 114   virtual ScrollbarSizes GetScrollbarSizes(nsPresContext*, StyleScrollbarWidth,
 115                                            Overlay) = 0;
 116
 117   /**
 118    * Return the border for the widget, in device pixels.
 119    */
 120   [[nodiscard]] virtual LayoutDeviceIntMargin GetWidgetBorder(
 121       nsDeviceContext* aContext, nsIFrame* aFrame,
 122       StyleAppearance aWidgetType) = 0;
 123
 124   /**
 125    * This method can return false to indicate that the CSS padding
 126    * value should be used.  Otherwise, it will fill in aResult with the
 127    * computed padding, in pixels, and return true.
 128    *
 129    * XXXldb This ought to be required to return true for non-containers
 130    * so that we don't let specified padding that has no effect change
 131    * the computed padding and potentially the size.
 132    */
 133   virtual bool GetWidgetPadding(nsDeviceContext* aContext, nsIFrame* aFrame,
 134                                 StyleAppearance aWidgetType,
 135                                 LayoutDeviceIntMargin* aResult) = 0;
 136
 137   /**
 138    * On entry, *aResult is positioned at 0,0 and sized to the new size
 139    * of aFrame (aFrame->GetSize() may be stale and should not be used).
 140    * This method can return false to indicate that no special
 141    * overflow area is required by the native widget. Otherwise it will
 142    * fill in aResult with the desired overflow area, in appunits, relative
 143    * to the frame origin, and return true.
 144    *
 145    * This overflow area is used to determine what area needs to be
 146    * repainted when the widget changes.  However, it does not affect the
 147    * widget's size or what area is reachable by scrollbars.  (In other
 148    * words, in layout terms, it affects ink overflow but not
 149    * scrollable overflow.)
 150    */
 151   virtual bool GetWidgetOverflow(nsDeviceContext* aContext, nsIFrame* aFrame,
 152                                  StyleAppearance aWidgetType,
 153                                  /*INOUT*/ nsRect* aOverflowRect) {
 154     return false;
 155   }
 156
 157   /**
 158    * Get the preferred content-box size of a checkbox / radio button, in app
 159    * units.  Historically 9px.
 160    */
 161   virtual nscoord GetCheckboxRadioPrefSize() {
 162     return mozilla::CSSPixel::ToAppUnits(9);
 163   }
 164
 165   /**
 166    * Get the minimum border-box size of a widget, in *pixels* (in
 167    * |aResult|).  If |aIsOverridable| is set to true, this size is a
 168    * minimum size; if false, this size is the only valid size for the
 169    * widget.
 170    */
 171   NS_IMETHOD GetMinimumWidgetSize(nsPresContext* aPresContext, nsIFrame* aFrame,
 172                                   StyleAppearance aWidgetType,
 173                                   mozilla::LayoutDeviceIntSize* aResult,
 174                                   bool* aIsOverridable) = 0;
 175
 176   enum Transparency { eOpaque = 0, eTransparent, eUnknownTransparency };
 177
 178   /**
 179    * Returns what we know about the transparency of the widget.
 180    */
 181   virtual Transparency GetWidgetTransparency(nsIFrame* aFrame,
 182                                              StyleAppearance aWidgetType) {
 183     return eUnknownTransparency;
 184   }
 185
 186   /**
 187    * Sets |*aShouldRepaint| to indicate whether an attribute or content state
 188    * change should trigger a repaint.  Call with null |aAttribute| (and
 189    * null |aOldValue|) for content state changes.
 190    */
 191   NS_IMETHOD WidgetStateChanged(nsIFrame* aFrame, StyleAppearance aWidgetType,
 192                                 nsAtom* aAttribute, bool* aShouldRepaint,
 193                                 const nsAttrValue* aOldValue) = 0;
 194
 195   NS_IMETHOD ThemeChanged() = 0;
 196
 197   virtual bool WidgetAppearanceDependsOnWindowFocus(
 198       StyleAppearance aWidgetType) {
 199     return false;
 200   }
 201
 202   /**
 203    * ThemeGeometryType values are used for describing themed nsIFrames in
 204    * calls to nsIWidget::UpdateThemeGeometries. We don't simply pass the
 205    * -moz-appearance value ("widget type") of the frame because the widget may
 206    * want to treat different frames with the same -moz-appearance differently
 207    * based on other properties of the frame. So we give the theme a first look
 208    * at the frame in nsITheme::ThemeGeometryTypeForWidget and pass the
 209    * returned ThemeGeometryType along to the widget.
 210    * Each theme backend defines the ThemeGeometryType values it needs in its
 211    * own nsITheme subclass. eThemeGeometryTypeUnknown is the only value that's
 212    * shared between backends.
 213    */
 214   typedef uint8_t ThemeGeometryType;
 215   enum { eThemeGeometryTypeUnknown = 0 };
 216
 217   /**
 218    * Returns the theme geometry type that should be used in the ThemeGeometry
 219    * array that's passed to the widget using nsIWidget::UpdateThemeGeometries.
 220    * A return value of eThemeGeometryTypeUnknown means that this frame will
 221    * not be included in the ThemeGeometry array.
 222    */
 223   virtual ThemeGeometryType ThemeGeometryTypeForWidget(
 224       nsIFrame* aFrame, StyleAppearance aWidgetType) {
 225     return eThemeGeometryTypeUnknown;
 226   }
 227
 228   /**
 229    * Can the nsITheme implementation handle this widget?
 230    */
 231   virtual bool ThemeSupportsWidget(nsPresContext* aPresContext,
 232                                    nsIFrame* aFrame,
 233                                    StyleAppearance aWidgetType) = 0;
 234
 235   virtual bool WidgetIsContainer(StyleAppearance aWidgetType) = 0;
 236
 237   /**
 238    * Does the nsITheme implementation draw its own focus ring for this widget?
 239    */
 240   virtual bool ThemeDrawsFocusForWidget(StyleAppearance aWidgetType) = 0;
 241
 242   /**
 243    * Whether we want an inner focus ring for buttons and such.
 244    *
 245    * Usually, we don't want it if we have our own focus indicators, but windows
 246    * is special, because it wants it even though focus also alters the border
 247    * color and such.
 248    */
 249   virtual bool ThemeWantsButtonInnerFocusRing(StyleAppearance aAppearance) {
 250     return !ThemeDrawsFocusForWidget(aAppearance);
 251   }
 252
 253   /**
 254    * Should we insert a dropmarker inside of combobox button?
 255    */
 256   virtual bool ThemeNeedsComboboxDropmarker() = 0;
 257
 258   virtual bool ThemeSupportsScrollbarButtons() { return true; }
 259 };
 260
 261 NS_DEFINE_STATIC_IID_ACCESSOR(nsITheme, NS_ITHEME_IID)
 262
 263 // Singleton accessor functions, these should never return null.
 264 //
 265 // Do not use directly, use nsPresContext::Theme instead.
 266 extern already_AddRefed<nsITheme> do_GetNativeThemeDoNotUseDirectly();
 267 extern already_AddRefed<nsITheme> do_GetBasicNativeThemeDoNotUseDirectly();
 268
 269 #endif