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 widget {
  36 class Theme;
  37 }  // namespace widget
  38 namespace wr {
  39 class DisplayListBuilder;
  40 class IpcResourceUpdateQueue;
  41 }  // namespace wr
  42 }  // namespace mozilla
  43
  44 // IID for the nsITheme interface
  45 // {7329f760-08cb-450f-8225-dae729096dec}
  46 #define NS_ITHEME_IID                                \
  47   {                                                  \
  48     0x7329f760, 0x08cb, 0x450f, {                    \
  49       0x82, 0x25, 0xda, 0xe7, 0x29, 0x09, 0x6d, 0xec \
  50     }                                                \
  51   }
  52
  53 /**
  54  * nsITheme is a service that provides platform-specific native
  55  * rendering for widgets.  In other words, it provides the necessary
  56  * operations to draw a rendering object (an nsIFrame) as a native
  57  * widget.
  58  *
  59  * All the methods on nsITheme take a rendering context or device
  60  * context, a frame (the rendering object), and a widget type (one of
  61  * the constants in nsThemeConstants.h).
  62  */
  63 class nsITheme : public nsISupports {
  64  protected:
  65   using LayoutDeviceIntMargin = mozilla::LayoutDeviceIntMargin;
  66   using LayoutDeviceIntSize = mozilla::LayoutDeviceIntSize;
  67   using LayoutDeviceIntCoord = mozilla::LayoutDeviceIntCoord;
  68   using StyleAppearance = mozilla::StyleAppearance;
  69   using StyleScrollbarWidth = mozilla::StyleScrollbarWidth;
  70   using ComputedStyle = mozilla::ComputedStyle;
  71
  72  public:
  73   NS_DECLARE_STATIC_IID_ACCESSOR(NS_ITHEME_IID)
  74
  75   /**
  76    * Draw the actual theme background.
  77    * @param aContext the context to draw into
  78    * @param aFrame the frame for the widget that we're drawing
  79    * @param aWidgetType the -moz-appearance value to draw
  80    * @param aRect the rectangle defining the area occupied by the widget
  81    * @param aDirtyRect the rectangle that needs to be drawn
  82    * @param DrawOverflow whether outlines, shadows and other such overflowing
  83    *        things should be drawn. Honoring this creates better results for
  84    *        box-shadow, though it's not a hard requirement.
  85    */
  86   enum class DrawOverflow { No, Yes };
  87   NS_IMETHOD DrawWidgetBackground(gfxContext* aContext, nsIFrame* aFrame,
  88                                   StyleAppearance aWidgetType,
  89                                   const nsRect& aRect, const nsRect& aDirtyRect,
  90                                   DrawOverflow = DrawOverflow::Yes) = 0;
  91
  92   /**
  93    * Create WebRender commands for the theme background.
  94    * @return true if the theme knows how to create WebRender commands for the
  95    *         given widget type, false if DrawWidgetBackground need sto be called
  96    *         instead.
  97    */
  98   virtual bool CreateWebRenderCommandsForWidget(
  99       mozilla::wr::DisplayListBuilder& aBuilder,
 100       mozilla::wr::IpcResourceUpdateQueue& aResources,
 101       const mozilla::layers::StackingContextHelper& aSc,
 102       mozilla::layers::RenderRootStateManager* aManager, nsIFrame* aFrame,
 103       StyleAppearance aWidgetType, const nsRect& aRect) {
 104     return false;
 105   }
 106
 107   /**
 108    * Returns the minimum widths of a scrollbar for a given style, that is, the
 109    * minimum width for a vertical scrollbar, and the minimum height of a
 110    * horizontal scrollbar.
 111    */
 112   enum class Overlay { No, Yes };
 113   virtual LayoutDeviceIntCoord GetScrollbarSize(const nsPresContext*,
 114                                                 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 device pixels.
 167    */
 168   virtual mozilla::LayoutDeviceIntSize GetMinimumWidgetSize(
 169       nsPresContext* aPresContext, nsIFrame* aFrame,
 170       StyleAppearance aWidgetType) = 0;
 171
 172   enum Transparency { eOpaque = 0, eTransparent, eUnknownTransparency };
 173
 174   /**
 175    * Returns what we know about the transparency of the widget.
 176    */
 177   virtual Transparency GetWidgetTransparency(nsIFrame* aFrame,
 178                                              StyleAppearance aWidgetType) {
 179     return eUnknownTransparency;
 180   }
 181
 182   /**
 183    * Sets |*aShouldRepaint| to indicate whether an attribute or content state
 184    * change should trigger a repaint.  Call with null |aAttribute| (and
 185    * null |aOldValue|) for content state changes.
 186    */
 187   NS_IMETHOD WidgetStateChanged(nsIFrame* aFrame, StyleAppearance aWidgetType,
 188                                 nsAtom* aAttribute, bool* aShouldRepaint,
 189                                 const nsAttrValue* aOldValue) = 0;
 190
 191   NS_IMETHOD ThemeChanged() = 0;
 192
 193   virtual bool WidgetAppearanceDependsOnWindowFocus(
 194       StyleAppearance aWidgetType) {
 195     return false;
 196   }
 197
 198   /**
 199    * ThemeGeometryType values are used for describing themed nsIFrames in
 200    * calls to nsIWidget::UpdateThemeGeometries. We don't simply pass the
 201    * -moz-appearance value ("widget type") of the frame because the widget may
 202    * want to treat different frames with the same -moz-appearance differently
 203    * based on other properties of the frame. So we give the theme a first look
 204    * at the frame in nsITheme::ThemeGeometryTypeForWidget and pass the
 205    * returned ThemeGeometryType along to the widget.
 206    * Each theme backend defines the ThemeGeometryType values it needs in its
 207    * own nsITheme subclass. eThemeGeometryTypeUnknown is the only value that's
 208    * shared between backends.
 209    */
 210   typedef uint8_t ThemeGeometryType;
 211   enum { eThemeGeometryTypeUnknown = 0 };
 212
 213   /**
 214    * Returns the theme geometry type that should be used in the ThemeGeometry
 215    * array that's passed to the widget using nsIWidget::UpdateThemeGeometries.
 216    * A return value of eThemeGeometryTypeUnknown means that this frame will
 217    * not be included in the ThemeGeometry array.
 218    */
 219   virtual ThemeGeometryType ThemeGeometryTypeForWidget(
 220       nsIFrame* aFrame, StyleAppearance aWidgetType) {
 221     return eThemeGeometryTypeUnknown;
 222   }
 223
 224   /**
 225    * Can the nsITheme implementation handle this widget?
 226    */
 227   virtual bool ThemeSupportsWidget(nsPresContext* aPresContext,
 228                                    nsIFrame* aFrame,
 229                                    StyleAppearance aWidgetType) = 0;
 230
 231   virtual bool WidgetIsContainer(StyleAppearance aWidgetType) = 0;
 232
 233   /**
 234    * Does the nsITheme implementation draw its own focus ring for this widget?
 235    */
 236   virtual bool ThemeDrawsFocusForWidget(nsIFrame*, StyleAppearance) = 0;
 237
 238   // Whether we want an inner focus ring for buttons and menulists.
 239   virtual bool ThemeWantsButtonInnerFocusRing() { return false; }
 240
 241   /**
 242    * Should we insert a dropmarker inside of combobox button?
 243    */
 244   virtual bool ThemeNeedsComboboxDropmarker() = 0;
 245
 246   virtual bool ThemeSupportsScrollbarButtons() = 0;
 247 };
 248
 249 NS_DEFINE_STATIC_IID_ACCESSOR(nsITheme, NS_ITHEME_IID)
 250
 251 // Singleton accessor functions, these should never return null.
 252 //
 253 // Do not use directly, use nsPresContext::Theme instead.
 254 extern already_AddRefed<nsITheme> do_GetNativeThemeDoNotUseDirectly();
 255 extern already_AddRefed<nsITheme> do_GetBasicNativeThemeDoNotUseDirectly();
 256 extern already_AddRefed<nsITheme> do_GetRDMThemeDoNotUseDirectly();
 257
 258 // Native theme creation function, these should never return null.
 259 extern already_AddRefed<mozilla::widget::Theme>
 260 do_CreateNativeThemeDoNotUseDirectly();
 261
 262 #endif