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nsCSSRendering.h (41126B)


      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 /* utility functions for drawing borders and backgrounds */
      8 
      9 #ifndef nsCSSRendering_h___
     10 #define nsCSSRendering_h___
     11 
     12 #include "gfxBlur.h"
     13 #include "gfxContext.h"
     14 #include "gfxTextRun.h"
     15 #include "mozilla/TypedEnumBits.h"
     16 #include "mozilla/gfx/PathHelpers.h"
     17 #include "mozilla/gfx/Rect.h"
     18 #include "nsCSSRenderingBorders.h"
     19 #include "nsIFrame.h"
     20 #include "nsImageRenderer.h"
     21 #include "nsStyleStruct.h"
     22 
     23 class gfxContext;
     24 class nsPresContext;
     25 
     26 namespace mozilla {
     27 
     28 class ComputedStyle;
     29 
     30 namespace gfx {
     31 struct sRGBColor;
     32 class DrawTarget;
     33 }  // namespace gfx
     34 
     35 namespace layers {
     36 class ImageContainer;
     37 class StackingContextHelper;
     38 class WebRenderParentCommand;
     39 class WebRenderLayerManager;
     40 class RenderRootStateManager;
     41 }  // namespace layers
     42 
     43 namespace wr {
     44 class DisplayListBuilder;
     45 }  // namespace wr
     46 
     47 enum class PaintBorderFlags : uint8_t { SyncDecodeImages = 1 << 0 };
     48 MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(PaintBorderFlags)
     49 
     50 }  // namespace mozilla
     51 
     52 /**
     53 * A struct representing all the information needed to paint a background
     54 * image to some target, taking into account all CSS background-* properties.
     55 * See PrepareImageLayer.
     56 */
     57 struct nsBackgroundLayerState {
     58  typedef mozilla::gfx::CompositionOp CompositionOp;
     59  typedef mozilla::nsImageRenderer nsImageRenderer;
     60 
     61  /**
     62   * @param aFlags some combination of nsCSSRendering::PAINTBG_* flags
     63   */
     64  nsBackgroundLayerState(nsIFrame* aForFrame, const mozilla::StyleImage* aImage,
     65                         uint32_t aFlags)
     66      : mImageRenderer(aForFrame, aImage, aFlags) {}
     67 
     68  /**
     69   * The nsImageRenderer that will be used to draw the background.
     70   */
     71  nsImageRenderer mImageRenderer;
     72  /**
     73   * A rectangle that one copy of the image tile is mapped onto. Same
     74   * coordinate system as aBorderArea/aBGClipRect passed into
     75   * PrepareImageLayer.
     76   */
     77  nsRect mDestArea;
     78  /**
     79   * The actual rectangle that should be filled with (complete or partial)
     80   * image tiles. Same coordinate system as aBorderArea/aBGClipRect passed into
     81   * PrepareImageLayer.
     82   */
     83  nsRect mFillArea;
     84  /**
     85   * The anchor point that should be snapped to a pixel corner. Same
     86   * coordinate system as aBorderArea/aBGClipRect passed into
     87   * PrepareImageLayer.
     88   */
     89  nsPoint mAnchor;
     90  /**
     91   * The background-repeat property space keyword computes the
     92   * repeat size which is image size plus spacing.
     93   */
     94  nsSize mRepeatSize;
     95 };
     96 
     97 struct nsCSSRendering {
     98  typedef mozilla::gfx::sRGBColor sRGBColor;
     99  typedef mozilla::gfx::CompositionOp CompositionOp;
    100  typedef mozilla::gfx::DrawTarget DrawTarget;
    101  typedef mozilla::gfx::Float Float;
    102  typedef mozilla::gfx::Point Point;
    103  typedef mozilla::gfx::Rect Rect;
    104  typedef mozilla::gfx::Size Size;
    105  typedef mozilla::gfx::RectCornerRadii RectCornerRadii;
    106  typedef mozilla::layers::WebRenderLayerManager WebRenderLayerManager;
    107  typedef mozilla::image::ImgDrawResult ImgDrawResult;
    108  typedef nsIFrame::Sides Sides;
    109 
    110  /**
    111   * Initialize any static variables used by nsCSSRendering.
    112   */
    113  static void Init();
    114 
    115  /**
    116   * Clean up any static variables used by nsCSSRendering.
    117   */
    118  static void Shutdown();
    119 
    120  static bool IsBoxDecorationSlice(const nsStyleBorder& aStyleBorder);
    121  static nsRect BoxDecorationRectForBorder(
    122      nsIFrame* aFrame, const nsRect& aBorderArea, Sides aSkipSides,
    123      const nsStyleBorder* aStyleBorder = nullptr);
    124  static nsRect BoxDecorationRectForBackground(
    125      nsIFrame* aFrame, const nsRect& aBorderArea, Sides aSkipSides,
    126      const nsStyleBorder* aStyleBorder = nullptr);
    127 
    128  static bool GetShadowInnerRadii(nsIFrame* aFrame, const nsRect& aFrameArea,
    129                                  RectCornerRadii& aOutInnerRadii);
    130  static nsRect GetBoxShadowInnerPaddingRect(nsIFrame* aFrame,
    131                                             const nsRect& aFrameArea);
    132  static bool ShouldPaintBoxShadowInner(nsIFrame* aFrame);
    133  static void PaintBoxShadowInner(nsPresContext* aPresContext,
    134                                  gfxContext& aRenderingContext,
    135                                  nsIFrame* aForFrame,
    136                                  const nsRect& aFrameArea);
    137 
    138  static bool GetBorderRadii(const nsRect& aFrameRect,
    139                             const nsRect& aBorderRect, nsIFrame* aFrame,
    140                             RectCornerRadii& aOutRadii);
    141  static nsRect GetShadowRect(const nsRect& aFrameArea, bool aNativeTheme,
    142                              nsIFrame* aForFrame);
    143  static mozilla::gfx::sRGBColor GetShadowColor(
    144      const mozilla::StyleSimpleShadow&, nsIFrame* aFrame, float aOpacity);
    145  // Returns if the frame has a themed frame.
    146  // aMaybeHasBorderRadius will return false if we can early detect
    147  // that we don't have a border radius.
    148  static bool HasBoxShadowNativeTheme(nsIFrame* aFrame,
    149                                      bool& aMaybeHasBorderRadius);
    150  static void PaintBoxShadowOuter(nsPresContext* aPresContext,
    151                                  gfxContext& aRenderingContext,
    152                                  nsIFrame* aForFrame, const nsRect& aFrameArea,
    153                                  const nsRect& aDirtyRect,
    154                                  float aOpacity = 1.0);
    155 
    156  static void ComputePixelRadii(const nsRectCornerRadii& aRadii,
    157                                nscoord aAppUnitsPerPixel,
    158                                RectCornerRadii* oBorderRadii);
    159 
    160  /**
    161   * Render the border for an element using css rendering rules
    162   * for borders. aSkipSides says which sides to skip
    163   * when rendering, the default is to skip none.
    164   */
    165  static ImgDrawResult PaintBorder(
    166      nsPresContext* aPresContext, gfxContext& aRenderingContext,
    167      nsIFrame* aForFrame, const nsRect& aDirtyRect, const nsRect& aBorderArea,
    168      mozilla::ComputedStyle* aStyle, mozilla::PaintBorderFlags aFlags,
    169      Sides aSkipSides = Sides());
    170 
    171  /**
    172   * Like PaintBorder, but taking an nsStyleBorder argument instead of
    173   * getting it from aStyle. aSkipSides says which sides to skip
    174   * when rendering, the default is to skip none.
    175   */
    176  static ImgDrawResult PaintBorderWithStyleBorder(
    177      nsPresContext* aPresContext, gfxContext& aRenderingContext,
    178      nsIFrame* aForFrame, const nsRect& aDirtyRect, const nsRect& aBorderArea,
    179      const nsStyleBorder& aBorderStyle, mozilla::ComputedStyle* aStyle,
    180      mozilla::PaintBorderFlags aFlags, Sides aSkipSides = Sides());
    181 
    182  static mozilla::Maybe<nsCSSBorderRenderer> CreateBorderRenderer(
    183      nsPresContext* aPresContext, DrawTarget* aDrawTarget, nsIFrame* aForFrame,
    184      const nsRect& aDirtyRect, const nsRect& aBorderArea,
    185      mozilla::ComputedStyle* aStyle, bool* aOutBorderIsEmpty,
    186      Sides aSkipSides = Sides());
    187 
    188  static mozilla::Maybe<nsCSSBorderRenderer>
    189  CreateBorderRendererWithStyleBorder(
    190      nsPresContext* aPresContext, DrawTarget* aDrawTarget, nsIFrame* aForFrame,
    191      const nsRect& aDirtyRect, const nsRect& aBorderArea,
    192      const nsStyleBorder& aBorderStyle, mozilla::ComputedStyle* aStyle,
    193      bool* aOutBorderIsEmpty, Sides aSkipSides = Sides());
    194 
    195  static mozilla::Maybe<nsCSSBorderRenderer>
    196  CreateNullBorderRendererWithStyleBorder(
    197      nsPresContext* aPresContext, DrawTarget* aDrawTarget, nsIFrame* aForFrame,
    198      const nsRect& aDirtyRect, const nsRect& aBorderArea,
    199      const nsStyleBorder& aBorderStyle, mozilla::ComputedStyle* aStyle,
    200      bool* aOutBorderIsEmpty, Sides aSkipSides = Sides());
    201 
    202  static mozilla::Maybe<nsCSSBorderRenderer>
    203  CreateBorderRendererForNonThemedOutline(nsPresContext* aPresContext,
    204                                          DrawTarget* aDrawTarget,
    205                                          nsIFrame* aForFrame,
    206                                          const nsRect& aDirtyRect,
    207                                          const nsRect& aInnerRect,
    208                                          mozilla::ComputedStyle* aStyle);
    209 
    210  static ImgDrawResult CreateWebRenderCommandsForBorder(
    211      mozilla::nsDisplayItem* aItem, nsIFrame* aForFrame,
    212      const nsRect& aBorderArea, mozilla::wr::DisplayListBuilder& aBuilder,
    213      mozilla::wr::IpcResourceUpdateQueue& aResources,
    214      const mozilla::layers::StackingContextHelper& aSc,
    215      mozilla::layers::RenderRootStateManager* aManager,
    216      mozilla::nsDisplayListBuilder* aDisplayListBuilder);
    217 
    218  static void CreateWebRenderCommandsForNullBorder(
    219      mozilla::nsDisplayItem* aItem, nsIFrame* aForFrame,
    220      const nsRect& aBorderArea, mozilla::wr::DisplayListBuilder& aBuilder,
    221      mozilla::wr::IpcResourceUpdateQueue& aResources,
    222      const mozilla::layers::StackingContextHelper& aSc,
    223      const nsStyleBorder& aStyleBorder);
    224 
    225  static ImgDrawResult CreateWebRenderCommandsForBorderWithStyleBorder(
    226      mozilla::nsDisplayItem* aItem, nsIFrame* aForFrame,
    227      const nsRect& aBorderArea, mozilla::wr::DisplayListBuilder& aBuilder,
    228      mozilla::wr::IpcResourceUpdateQueue& aResources,
    229      const mozilla::layers::StackingContextHelper& aSc,
    230      mozilla::layers::RenderRootStateManager* aManager,
    231      mozilla::nsDisplayListBuilder* aDisplayListBuilder,
    232      const nsStyleBorder& aStyleBorder);
    233 
    234  /**
    235   * Render the outline for an element using css rendering rules for borders.
    236   */
    237  static void PaintNonThemedOutline(nsPresContext* aPresContext,
    238                                    gfxContext& aRenderingContext,
    239                                    nsIFrame* aForFrame,
    240                                    const nsRect& aDirtyRect,
    241                                    const nsRect& aInnerRect,
    242                                    mozilla::ComputedStyle* aStyle);
    243 
    244  /**
    245   * Render keyboard focus on an element.
    246   * |aFocusRect| is the outer rectangle of the focused element.
    247   * Uses a fixed style equivalent to "1px dotted |aColor|".
    248   * Not used for controls, because the native theme may differ.
    249   */
    250  static nsCSSBorderRenderer GetBorderRendererForFocus(nsIFrame*, DrawTarget*,
    251                                                       const nsRect& aFocusRect,
    252                                                       nscolor aColor);
    253 
    254  /**
    255   * Render a gradient for an element.
    256   * aDest is the rect for a single tile of the gradient on the destination.
    257   * aFill is the rect on the destination to be covered by repeated tiling of
    258   * the gradient.
    259   * aSrc is the part of the gradient to be rendered into a tile (aDest), if
    260   * aSrc and aDest are different sizes, the image will be scaled to map aSrc
    261   * onto aDest.
    262   * aIntrinsicSize is the size of the source gradient.
    263   */
    264  static void PaintGradient(nsPresContext* aPresContext, gfxContext& aContext,
    265                            const mozilla::StyleGradient& aGradient,
    266                            const nsRect& aDirtyRect, const nsRect& aDest,
    267                            const nsRect& aFill, const nsSize& aRepeatSize,
    268                            const mozilla::CSSIntRect& aSrc,
    269                            const nsSize& aIntrinsiceSize,
    270                            float aOpacity = 1.0);
    271 
    272  /**
    273   * Find the frame whose background style should be used to draw the
    274   * canvas background. aForFrame must be the frame for the root element
    275   * whose background style should be used. This function will return
    276   * aForFrame unless the <body> background should be propagated, in
    277   * which case we return the frame associated with the <body>'s background.
    278   */
    279  static nsIFrame* FindBackgroundStyleFrame(nsIFrame* aForFrame);
    280 
    281  /**
    282   * Returns the ComputedStyle to be used to paint the background for the given
    283   * frame, if its element has a meaningful background.  This applies the rules
    284   * for propagating backgrounds between BODY, the root element, and the
    285   * canvas.
    286   *
    287   * @return the ComputedStyle (if any) to be used for painting aForFrame's
    288   *         background.
    289   */
    290  static mozilla::ComputedStyle* FindBackground(const nsIFrame* aForFrame);
    291  static nsIFrame* FindBackgroundFrame(const nsIFrame* aForFrame);
    292 
    293  /**
    294   * As FindBackground, but the passed-in frame is known to be a root frame
    295   * (returned from nsCSSFrameConstructor::GetRootElementStyleFrame())
    296   * and there is always some meaningful background returned.
    297   */
    298  static mozilla::ComputedStyle* FindRootFrameBackground(nsIFrame* aForFrame);
    299 
    300  /**
    301   * Find a non-transparent background color on an ancestor, for various
    302   * contrast checks. Note that this only accounts for background-color and
    303   * might stop at themed frames (depending on the argument), so it might not be
    304   * what you want. Note that if we stop at themed frames we might, in fact, end
    305   * up returning a transparent color (but then mIsThemed will be set to true).
    306   *
    307   * For semi-transparent colors, right now we blend with the default
    308   * background-color rather than with all ancestor backgrounds.
    309   *
    310   * If aPreferBodyToCanvas is true, we prefer the background color of the
    311   * <body> frame, even though we found a canvas background, because the body
    312   * background color is most likely what will be visible as the background
    313   * color of the page, even if the html element has a different background
    314   * color which prevents that of the body frame to propagate to the viewport.
    315   */
    316  struct EffectiveBackgroundColor {
    317    nscolor mColor = 0;
    318    bool mIsThemed = false;
    319  };
    320  static EffectiveBackgroundColor FindEffectiveBackgroundColor(
    321      nsIFrame* aFrame, bool aStopAtThemed = true,
    322      bool aPreferBodyToCanvas = false);
    323 
    324  /**
    325   * Determine the background color to draw taking into account print settings.
    326   */
    327  static nscolor DetermineBackgroundColor(nsPresContext* aPresContext,
    328                                          const mozilla::ComputedStyle* aStyle,
    329                                          nsIFrame* aFrame,
    330                                          bool& aDrawBackgroundImage,
    331                                          bool& aDrawBackgroundColor);
    332 
    333  static nsRect ComputeImageLayerPositioningArea(
    334      nsPresContext* aPresContext, nsIFrame* aForFrame,
    335      const nsRect& aBorderArea, const nsStyleImageLayers::Layer& aLayer,
    336      nsIFrame** aAttachedToFrame, bool* aOutTransformedFixed);
    337 
    338  // Implementation of the formula for computation of background-repeat round
    339  // See http://dev.w3.org/csswg/css3-background/#the-background-size
    340  // This function returns the adjusted size of the background image.
    341  static nscoord ComputeRoundedSize(nscoord aCurrentSize,
    342                                    nscoord aPositioningSize);
    343 
    344  /* ComputeBorderSpacedRepeatSize
    345   * aImageDimension: the image width/height
    346   * aAvailableSpace: the background positioning area width/height
    347   * aSpace: the space between each image
    348   * Returns the image size plus gap size of app units for use as spacing
    349   */
    350  static nscoord ComputeBorderSpacedRepeatSize(nscoord aImageDimension,
    351                                               nscoord aAvailableSpace,
    352                                               nscoord& aSpace);
    353 
    354  static nsBackgroundLayerState PrepareImageLayer(
    355      nsPresContext* aPresContext, nsIFrame* aForFrame, uint32_t aFlags,
    356      const nsRect& aBorderArea, const nsRect& aBGClipRect,
    357      const nsStyleImageLayers::Layer& aLayer,
    358      bool* aOutIsTransformedFixed = nullptr);
    359 
    360  struct ImageLayerClipState {
    361    nsRect mBGClipArea;            // Affected by mClippedRadii
    362    nsRect mAdditionalBGClipArea;  // Not affected by mClippedRadii
    363    nsRect mDirtyRectInAppUnits;
    364    gfxRect mDirtyRectInDevPx;
    365 
    366    nsRectCornerRadii mRadii;
    367    RectCornerRadii mClippedRadii;
    368    bool mHasRoundedCorners;
    369    bool mHasAdditionalBGClipArea;
    370 
    371    // Whether we are being asked to draw with a caller provided background
    372    // clipping area. If this is true we also disable rounded corners.
    373    bool mCustomClip;
    374 
    375    ImageLayerClipState()
    376        : mHasRoundedCorners(false),
    377          mHasAdditionalBGClipArea(false),
    378          mCustomClip(false) {}
    379 
    380    bool IsValid() const;
    381  };
    382 
    383  static void GetImageLayerClip(const nsStyleImageLayers::Layer& aLayer,
    384                                nsIFrame* aForFrame,
    385                                const nsStyleBorder& aBorder,
    386                                const nsRect& aBorderArea,
    387                                const nsRect& aCallerDirtyRect,
    388                                bool aWillPaintBorder,
    389                                nscoord aAppUnitsPerPixel,
    390                                /* out */ ImageLayerClipState* aClipState);
    391 
    392  /**
    393   * Render the background for an element using css rendering rules
    394   * for backgrounds or mask.
    395   */
    396  enum {
    397    /**
    398     * When this flag is passed, the element's nsDisplayBorder will be
    399     * painted immediately on top of this background.
    400     */
    401    PAINTBG_WILL_PAINT_BORDER = 0x01,
    402    /**
    403     * When this flag is passed, images are synchronously decoded.
    404     */
    405    PAINTBG_SYNC_DECODE_IMAGES = 0x02,
    406    /**
    407     * When this flag is passed, painting will go to the screen so we can
    408     * take advantage of the fact that it will be clipped to the viewport.
    409     */
    410    PAINTBG_TO_WINDOW = 0x04,
    411    /**
    412     * When this flag is passed, painting will read properties of mask-image
    413     * style, instead of background-image.
    414     */
    415    PAINTBG_MASK_IMAGE = 0x08,
    416    /**
    417     * When this flag is passed, images are downscaled during decode. This
    418     * is also implied by PAINTBG_TO_WINDOW.
    419     */
    420    PAINTBG_HIGH_QUALITY_SCALING = 0x10,
    421  };
    422 
    423  struct PaintBGParams {
    424    nsPresContext& presCtx;
    425    nsRect dirtyRect;
    426    nsRect borderArea;
    427    nsIFrame* frame;
    428    uint32_t paintFlags;
    429    nsRect* bgClipRect = nullptr;
    430    int32_t layer;  // -1 means painting all layers; other
    431                    // value means painting one specific
    432                    // layer only.
    433    CompositionOp compositionOp;
    434    float opacity;
    435 
    436    static PaintBGParams ForAllLayers(nsPresContext& aPresCtx,
    437                                      const nsRect& aDirtyRect,
    438                                      const nsRect& aBorderArea,
    439                                      nsIFrame* aFrame, uint32_t aPaintFlags,
    440                                      float aOpacity = 1.0);
    441    static PaintBGParams ForSingleLayer(
    442        nsPresContext& aPresCtx, const nsRect& aDirtyRect,
    443        const nsRect& aBorderArea, nsIFrame* aFrame, uint32_t aPaintFlags,
    444        int32_t aLayer, CompositionOp aCompositionOp = CompositionOp::OP_OVER,
    445        float aOpacity = 1.0);
    446 
    447   private:
    448    PaintBGParams(nsPresContext& aPresCtx, const nsRect& aDirtyRect,
    449                  const nsRect& aBorderArea, nsIFrame* aFrame,
    450                  uint32_t aPaintFlags, int32_t aLayer,
    451                  CompositionOp aCompositionOp, float aOpacity)
    452        : presCtx(aPresCtx),
    453          dirtyRect(aDirtyRect),
    454          borderArea(aBorderArea),
    455          frame(aFrame),
    456          paintFlags(aPaintFlags),
    457          layer(aLayer),
    458          compositionOp(aCompositionOp),
    459          opacity(aOpacity) {}
    460  };
    461 
    462  static ImgDrawResult PaintStyleImageLayer(const PaintBGParams& aParams,
    463                                            gfxContext& aRenderingCtx);
    464 
    465  /**
    466   * Same as |PaintStyleImageLayer|, except using the provided style structs.
    467   * This short-circuits the code that ensures that the root element's
    468   * {background|mask} is drawn on the canvas.
    469   * The aLayer parameter allows you to paint a single layer of the
    470   * {background|mask}.
    471   * The default value for aLayer, -1, means that all layers will be painted.
    472   * The background color will only be painted if the back-most layer is also
    473   * being painted and (aParams.paintFlags & PAINTBG_MASK_IMAGE) is false.
    474   * aCompositionOp is only respected if a single layer is specified (aLayer !=
    475   * -1). If all layers are painted, the image layer's blend mode (or the mask
    476   * layer's composition mode) will be used.
    477   */
    478  static ImgDrawResult PaintStyleImageLayerWithSC(
    479      const PaintBGParams& aParams, gfxContext& aRenderingCtx,
    480      const mozilla::ComputedStyle* aBackgroundSC,
    481      const nsStyleBorder& aBorder);
    482 
    483  static bool CanBuildWebRenderDisplayItemsForStyleImageLayer(
    484      WebRenderLayerManager* aManager, nsPresContext& aPresCtx,
    485      nsIFrame* aFrame, const nsStyleBackground* aBackgroundStyle,
    486      int32_t aLayer, uint32_t aPaintFlags);
    487  static ImgDrawResult BuildWebRenderDisplayItemsForStyleImageLayer(
    488      const PaintBGParams& aParams, mozilla::wr::DisplayListBuilder& aBuilder,
    489      mozilla::wr::IpcResourceUpdateQueue& aResources,
    490      const mozilla::layers::StackingContextHelper& aSc,
    491      mozilla::layers::RenderRootStateManager* aManager,
    492      mozilla::nsDisplayItem* aItem);
    493 
    494  static ImgDrawResult BuildWebRenderDisplayItemsForStyleImageLayerWithSC(
    495      const PaintBGParams& aParams, mozilla::wr::DisplayListBuilder& aBuilder,
    496      mozilla::wr::IpcResourceUpdateQueue& aResources,
    497      const mozilla::layers::StackingContextHelper& aSc,
    498      mozilla::layers::RenderRootStateManager* aManager,
    499      mozilla::nsDisplayItem* aItem, mozilla::ComputedStyle* mBackgroundSC,
    500      const nsStyleBorder& aBorder);
    501 
    502  /**
    503   * Returns the rectangle covered by the given background layer image, taking
    504   * into account background positioning, sizing, and repetition, but not
    505   * clipping.
    506   */
    507  static nsRect GetBackgroundLayerRect(nsPresContext* aPresContext,
    508                                       nsIFrame* aForFrame,
    509                                       const nsRect& aBorderArea,
    510                                       const nsRect& aClipRect,
    511                                       const nsStyleImageLayers::Layer& aLayer,
    512                                       uint32_t aFlags);
    513 
    514  /**
    515   * Called when we start creating a display list. The frame tree will not
    516   * change until a matching EndFrameTreeLocked is called.
    517   */
    518  static void BeginFrameTreesLocked();
    519  /**
    520   * Called when we've finished using a display list. When all
    521   * BeginFrameTreeLocked calls have been balanced by an EndFrameTreeLocked,
    522   * the frame tree may start changing again.
    523   */
    524  static void EndFrameTreesLocked();
    525 
    526  // Draw a border segment in the table collapsing border model with beveling
    527  // corners.
    528  static void DrawTableBorderSegment(
    529      DrawTarget& aDrawTarget, mozilla::StyleBorderStyle aBorderStyle,
    530      nscolor aBorderColor, const nsRect& aBorderRect,
    531      int32_t aAppUnitsPerDevPixel, mozilla::Side aStartBevelSide,
    532      nscoord aStartBevelOffset, mozilla::Side aEndBevelSide,
    533      nscoord aEndBevelOffset);
    534 
    535  // A single border bevel.
    536  struct Bevel {
    537    mozilla::Side mSide;
    538    nscoord mOffset;
    539  };
    540 
    541  // A single solid beveled border segment.
    542  struct SolidBeveledBorderSegment {
    543    nsRect mRect;
    544    nscolor mColor;
    545    Bevel mStartBevel;
    546    Bevel mEndBevel;
    547  };
    548 
    549  // Collect the table border segments with beveling. Can't be called with
    550  // dashed / dotted borders, since we don't support beveling those.
    551  static void GetTableBorderSolidSegments(
    552      nsTArray<SolidBeveledBorderSegment>& aSegments,
    553      mozilla::StyleBorderStyle aBorderStyle, nscolor aBorderColor,
    554      const nsRect& aBorderRect, int32_t aAppUnitsPerDevPixel,
    555      mozilla::Side aStartBevelSide, nscoord aStartBevelOffset,
    556      mozilla::Side aEndBevelSide, nscoord aEndBevelOffset);
    557 
    558  // NOTE: pt, dirtyRect, lineSize, ascent, offset, insetLeft, and insetRight in
    559  //       the following structs are non-rounded device pixels, not app units.
    560  struct DecorationRectParams {
    561    // Checks if either start or end inset value is negative.
    562    // In that situation, text decoration will extend past the edges of the
    563    // text.
    564    bool HasNegativeInset() const {
    565      return insetLeft < 0.0 || insetRight < 0.0;
    566    }
    567 
    568    // The width [length] and the height [thickness] of the decoration
    569    // line. This is a "logical" size in textRun orientation, so that
    570    // for a vertical textrun, width will actually be a physical height;
    571    // and conversely, height will be a physical width.
    572    Size lineSize;
    573    // The default height [thickness] of the line given by the font metrics.
    574    // This is used for obtaining the correct offset for the decoration line
    575    // when CSS specifies a unique thickness for a text-decoration,
    576    // since the offset given by the font is derived from the font metric's
    577    // assumed line height
    578    Float defaultLineThickness = 0.0f;
    579    // The ascent of the text.
    580    Float ascent = 0.0f;
    581    // The offset of the decoration line from the baseline of the text
    582    // (if the value is positive, the line is lifted up).
    583    Float offset = 0.0f;
    584    // If descentLimit is zero or larger and the underline overflows
    585    // from the descent space, the underline should be lifted up as far
    586    // as possible.  Note that this does not mean the underline never
    587    // overflows from this limitation, because if the underline is
    588    // positioned to the baseline or upper, it causes unreadability.
    589    // Note that if this is zero or larger, the underline rect may be
    590    // shrunken if it's possible.  Therefore, this value is used for
    591    // strikeout line and overline too.
    592    Float descentLimit = -1.0f;
    593    // Which line will be painted. The value can be
    594    // UNDERLINE or OVERLINE or LINE_THROUGH.
    595    mozilla::StyleTextDecorationLine decoration =
    596        mozilla::StyleTextDecorationLine::UNDERLINE;
    597    // The style of the decoration line
    598    mozilla::StyleTextDecorationStyle style =
    599        mozilla::StyleTextDecorationStyle::None;
    600    // Decoration-line start/end inset values for this decoration.
    601    // The caller must ensure that the start/end values are translated to
    602    // left/right in the line-relative direction.
    603    Float insetLeft = 0.0f;
    604    Float insetRight = 0.0f;
    605    bool vertical = false;
    606    bool sidewaysLeft = false;
    607    gfxTextRun::Range glyphRange;
    608    gfxTextRun::PropertyProvider* provider = nullptr;
    609  };
    610 
    611  struct PaintDecorationLineParams : DecorationRectParams {
    612    // No need to paint outside this rect.
    613    Rect dirtyRect;
    614    // The top/left edge of the text.
    615    Point pt;
    616    // The color of the decoration line.
    617    nscolor color = NS_RGBA(0, 0, 0, 0);
    618    // The distance between the left edge of the given frame and the
    619    // position of the text as positioned without offset of the shadow.
    620    Float icoordInFrame = 0.0f;
    621    // Baseline offset being applied to this text (block-direction adjustment
    622    // applied to glyph positions when computing skip-ink intercepts).
    623    Float baselineOffset = 0.0f;
    624    // Whether text-decoration-skip-ink behavior is to be supported.
    625    bool allowInkSkipping = true;
    626 
    627    mozilla::StyleTextDecorationSkipInk skipInk =
    628        mozilla::StyleTextDecorationSkipInk::None;
    629  };
    630 
    631  /**
    632   * Function for painting the clipped decoration lines for the text.
    633   * Takes into account the rect clipping that occurs when
    634   * text-decoration-skip-ink is being used for underlines or overlines
    635   *
    636   *  input:
    637   *    @param aFrame            the frame which needs the decoration line
    638   *    @param aDrawTarget       the target/backend being drawn to
    639   *    @param aParams           the parameters for the decoration line
    640   *                             being drawn
    641   *    @param aRect             the rect representing the decoration line
    642   */
    643  static void PaintDecorationLineInternal(
    644      nsIFrame* aFrame, DrawTarget& aDrawTarget,
    645      const PaintDecorationLineParams& aParams, Rect aRect);
    646 
    647  /**
    648   * Function for painting the decoration lines for the text.
    649   *
    650   *   input:
    651   *     @param aFrame            the frame which needs the decoration line
    652   *     @param aDrawTarget       the target/backend being drawn to
    653   *     @param aParams           the parameters for the decoration line
    654   *                              being drawn
    655   */
    656  static void PaintDecorationLine(nsIFrame* aFrame, DrawTarget& aDrawTarget,
    657                                  const PaintDecorationLineParams& aParams);
    658 
    659  /**
    660   * Returns a Rect corresponding to the outline of the decoration line for the
    661   * given text metrics.  Arguments have the same meaning as for
    662   * PaintDecorationLine.  Currently this only works for solid
    663   * decorations; for other decoration styles the returned Rect will be empty.
    664   */
    665  static Rect DecorationLineToPath(const PaintDecorationLineParams& aParams);
    666 
    667  /**
    668   * Function for getting the decoration line rect for the text.
    669   * NOTE: aLineSize, aAscent and aOffset are non-rounded device pixels,
    670   *       not app units.
    671   *   input:
    672   *     @param aPresContext
    673   *   output:
    674   *     @return                  the decoration line rect for the input,
    675   *                              the each values are app units.
    676   */
    677  static nsRect GetTextDecorationRect(nsPresContext* aPresContext,
    678                                      const DecorationRectParams& aParams);
    679 
    680  static CompositionOp GetGFXBlendMode(mozilla::StyleBlend aBlendMode) {
    681    switch (aBlendMode) {
    682      case mozilla::StyleBlend::Normal:
    683        return CompositionOp::OP_OVER;
    684      case mozilla::StyleBlend::Multiply:
    685        return CompositionOp::OP_MULTIPLY;
    686      case mozilla::StyleBlend::Screen:
    687        return CompositionOp::OP_SCREEN;
    688      case mozilla::StyleBlend::Overlay:
    689        return CompositionOp::OP_OVERLAY;
    690      case mozilla::StyleBlend::Darken:
    691        return CompositionOp::OP_DARKEN;
    692      case mozilla::StyleBlend::Lighten:
    693        return CompositionOp::OP_LIGHTEN;
    694      case mozilla::StyleBlend::ColorDodge:
    695        return CompositionOp::OP_COLOR_DODGE;
    696      case mozilla::StyleBlend::ColorBurn:
    697        return CompositionOp::OP_COLOR_BURN;
    698      case mozilla::StyleBlend::HardLight:
    699        return CompositionOp::OP_HARD_LIGHT;
    700      case mozilla::StyleBlend::SoftLight:
    701        return CompositionOp::OP_SOFT_LIGHT;
    702      case mozilla::StyleBlend::Difference:
    703        return CompositionOp::OP_DIFFERENCE;
    704      case mozilla::StyleBlend::Exclusion:
    705        return CompositionOp::OP_EXCLUSION;
    706      case mozilla::StyleBlend::Hue:
    707        return CompositionOp::OP_HUE;
    708      case mozilla::StyleBlend::Saturation:
    709        return CompositionOp::OP_SATURATION;
    710      case mozilla::StyleBlend::Color:
    711        return CompositionOp::OP_COLOR;
    712      case mozilla::StyleBlend::Luminosity:
    713        return CompositionOp::OP_LUMINOSITY;
    714      case mozilla::StyleBlend::PlusLighter:
    715        return CompositionOp::OP_ADD;
    716      default:
    717        MOZ_ASSERT(false);
    718        return CompositionOp::OP_OVER;
    719    }
    720  }
    721 
    722  static CompositionOp GetGFXCompositeMode(
    723      mozilla::StyleMaskComposite aCompositeMode) {
    724    switch (aCompositeMode) {
    725      case mozilla::StyleMaskComposite::Add:
    726        return CompositionOp::OP_OVER;
    727      case mozilla::StyleMaskComposite::Subtract:
    728        return CompositionOp::OP_OUT;
    729      case mozilla::StyleMaskComposite::Intersect:
    730        return CompositionOp::OP_IN;
    731      case mozilla::StyleMaskComposite::Exclude:
    732        return CompositionOp::OP_XOR;
    733      default:
    734        MOZ_ASSERT(false);
    735        return CompositionOp::OP_OVER;
    736    }
    737  }
    738 
    739 protected:
    740  static gfxRect GetTextDecorationRectInternal(
    741      const Point& aPt, const DecorationRectParams& aParams);
    742 
    743  /**
    744   * Returns inflated rect for painting a decoration line.
    745   * Complex style decoration lines should be painted from leftmost of nearest
    746   * ancestor block box because that makes better look of connection of lines
    747   * for different nodes.  ExpandPaintingRectForDecorationLine() returns
    748   * a rect for actual painting rect for the clipped rect.
    749   *
    750   * input:
    751   *     @param aFrame            the frame which needs the decoration line.
    752   *     @param aStyle            the style of the complex decoration line
    753   *     @param aClippedRect      the clipped rect for the decoration line.
    754   *                              in other words, visible area of the line.
    755   *     @param aICoordInFrame  the distance between inline-start edge of aFrame
    756   *                              and aClippedRect.pos.
    757   *     @param aCycleLength      the width of one cycle of the line style.
    758   */
    759  static Rect ExpandPaintingRectForDecorationLine(
    760      nsIFrame* aFrame, const mozilla::StyleTextDecorationStyle aStyle,
    761      const Rect& aClippedRect, const Float aICoordInFrame,
    762      const Float aCycleLength, bool aVertical);
    763 };
    764 
    765 /*
    766 * nsContextBoxBlur
    767 * Creates an 8-bit alpha channel context for callers to draw in, blurs the
    768 * contents of that context and applies it as a 1-color mask on a
    769 * different existing context. Uses gfxGaussianBlur as its back end.
    770 *
    771 * You must call Init() first to create a suitable temporary surface to draw
    772 * on.  You must then draw any desired content onto the given context, then
    773 * call DoPaint() to apply the blurred content as a single-color mask. You
    774 * can only call Init() once, so objects cannot be reused.
    775 *
    776 * This is very useful for creating drop shadows or silhouettes.
    777 */
    778 class nsContextBoxBlur {
    779  typedef mozilla::gfx::sRGBColor sRGBColor;
    780  typedef mozilla::gfx::DrawTarget DrawTarget;
    781  typedef mozilla::gfx::RectCornerRadii RectCornerRadii;
    782 
    783 public:
    784  enum { FORCE_MASK = 0x01 };
    785  /**
    786   * Prepares a gfxContext to draw on. Do not call this twice; if you want
    787   * to get the gfxContext again use GetContext().
    788   *
    789   * @param aRect                The coordinates of the surface to create.
    790   *                             All coordinates must be in app units.
    791   *                             This must not include the blur radius, pass
    792   *                             it as the second parameter and everything
    793   *                             is taken care of.
    794   *
    795   * @param aBlurRadius          The blur radius in app units.
    796   *
    797   * @param aAppUnitsPerDevPixel The number of app units in a device pixel,
    798   *                             for conversion.  Most of the time you'll
    799   *                             pass this from the current PresContext if
    800   *                             available.
    801   *
    802   * @param aDestinationCtx      The graphics context to apply the blurred
    803   *                             mask to when you call DoPaint(). Make sure
    804   *                             it is not destroyed before you call
    805   *                             DoPaint(). To set the color of the
    806   *                             resulting blurred graphic mask, you must
    807   *                             set the color on this context before
    808   *                             calling Init().
    809   *
    810   * @param aDirtyRect           The absolute dirty rect in app units. Used to
    811   *                             optimize the temporary surface size and speed
    812   * up blur.
    813   *
    814   * @param aSkipRect            An area in device pixels (NOT app units!) to
    815   * avoid blurring over, to prevent unnecessary work.
    816   *
    817   * @param aFlags               FORCE_MASK to ensure that the content drawn to
    818   * the returned gfxContext is used as a mask, and not drawn directly to
    819   * aDestinationCtx.
    820   *
    821   * @return            A blank 8-bit alpha-channel-only graphics context to
    822   *                    draw on, or null on error. Must not be freed. The
    823   *                    context has a device offset applied to it given by
    824   *                    aRect. This means you can use coordinates as if it
    825   *                    were at the desired position at aRect and you don't
    826   *                    need to worry about translating any coordinates to
    827   *                    draw on this temporary surface.
    828   *
    829   * If aBlurRadius is 0, the returned context is aDestinationCtx and
    830   * DoPaint() does nothing, because no blurring is required. Therefore, you
    831   * should prepare the destination context as if you were going to draw
    832   * directly on it instead of any temporary surface created in this class.
    833   */
    834  gfxContext* Init(const nsRect& aRect, nscoord aSpreadRadius,
    835                   nscoord aBlurRadius, int32_t aAppUnitsPerDevPixel,
    836                   gfxContext* aDestinationCtx, const nsRect& aDirtyRect,
    837                   const gfxRect* aSkipRect, uint32_t aFlags = 0);
    838 
    839  /**
    840   * Does the actual blurring and mask applying. Users of this object *must*
    841   * have called Init() first, then have drawn whatever they want to be
    842   * blurred onto the internal gfxContext before calling this.
    843   */
    844  void DoPaint();
    845 
    846  /**
    847   * Gets the internal gfxContext at any time. Must not be freed. Avoid
    848   * calling this before calling Init() since the context would not be
    849   * constructed at that point.
    850   */
    851  gfxContext* GetContext();
    852 
    853  /**
    854   * Get the margin associated with the given blur radius, i.e., the
    855   * additional area that might be painted as a result of it.  (The
    856   * margin for a spread radius is itself, on all sides.)
    857   */
    858  static nsMargin GetBlurRadiusMargin(nscoord aBlurRadius,
    859                                      int32_t aAppUnitsPerDevPixel);
    860 
    861  /**
    862   * Blurs a coloured rectangle onto aDestinationCtx. This is equivalent
    863   * to calling Init(), drawing a rectangle onto the returned surface
    864   * and then calling DoPaint, but may let us optimize better in the
    865   * backend.
    866   *
    867   * @param aDestinationCtx      The destination to blur to.
    868   * @param aRect                The rectangle to blur in app units.
    869   * @param aAppUnitsPerDevPixel The number of app units in a device pixel,
    870   *                             for conversion.  Most of the time you'll
    871   *                             pass this from the current PresContext if
    872   *                             available.
    873   * @param aCornerRadii         Corner radii for aRect, if it is a rounded
    874   *                             rectangle.
    875   * @param aBlurRadius          The blur radius in app units.
    876   * @param aShadowColor         The color to draw the blurred shadow.
    877   * @param aDirtyRect           The absolute dirty rect in app units. Used to
    878   *                             optimize the temporary surface size and speed
    879   * up blur.
    880   * @param aSkipRect            An area in device pixels (NOT app units!) to
    881   * avoid blurring over, to prevent unnecessary work.
    882   */
    883  static void BlurRectangle(gfxContext* aDestinationCtx, const nsRect& aRect,
    884                            int32_t aAppUnitsPerDevPixel,
    885                            RectCornerRadii* aCornerRadii, nscoord aBlurRadius,
    886                            const sRGBColor& aShadowColor,
    887                            const nsRect& aDirtyRect, const gfxRect& aSkipRect);
    888 
    889  /**
    890   * Draws a blurred inset box shadow shape onto the destination surface.
    891   * Like BlurRectangle, this is equivalent to calling Init(),
    892   * drawing a rectangle onto the returned surface
    893   * and then calling DoPaint, but may let us optimize better in the
    894   * backend.
    895   *
    896   * @param aDestinationCtx      The destination to blur to.
    897   * @param aDestinationRect     The rectangle to blur in app units.
    898   * @param aShadowClipRect      The inside clip rect that creates the path.
    899   * @param aShadowColor         The color of the blur
    900   * @param aBlurRadiusAppUnits  The blur radius in app units
    901   * @param aSpreadRadiusAppUnits The spread radius in app units.
    902   * @param aAppUnitsPerDevPixel The number of app units in a device pixel,
    903   *                             for conversion.  Most of the time you'll
    904   *                             pass this from the current PresContext if
    905   *                             available.
    906   * @param aHasBorderRadius     If this inset box blur has a border radius
    907   * @param aInnerClipRectRadii  The clip rect radii used for the inside rect's
    908   * path.
    909   * @param aSkipRect            An area in device pixels (NOT app units!) to
    910   * avoid blurring over, to prevent unnecessary work.
    911   */
    912  bool InsetBoxBlur(gfxContext* aDestinationCtx,
    913                    mozilla::gfx::Rect aDestinationRect,
    914                    mozilla::gfx::Rect aShadowClipRect,
    915                    mozilla::gfx::sRGBColor& aShadowColor,
    916                    nscoord aBlurRadiusAppUnits, nscoord aSpreadRadiusAppUnits,
    917                    int32_t aAppUnitsPerDevPixel, bool aHasBorderRadius,
    918                    RectCornerRadii& aInnerClipRectRadii,
    919                    mozilla::gfx::Rect aSkipRect,
    920                    mozilla::gfx::Point aShadowOffset);
    921 
    922 protected:
    923  static void GetBlurAndSpreadRadius(DrawTarget* aDestDrawTarget,
    924                                     int32_t aAppUnitsPerDevPixel,
    925                                     nscoord aBlurRadius, nscoord aSpreadRadius,
    926                                     mozilla::gfx::IntSize& aOutBlurRadius,
    927                                     mozilla::gfx::IntSize& aOutSpreadRadius,
    928                                     bool aConstrainSpreadRadius = true);
    929 
    930  gfxGaussianBlur mGaussianBlur;
    931  mozilla::UniquePtr<gfxContext> mOwnedContext;
    932  gfxContext* mContext;  // may be either mOwnedContext or mDestinationContext
    933  gfxContext* mDestinationCtx;
    934 
    935  /* This is true if the blur already has it's content transformed
    936   * by mDestinationCtx's transform */
    937  bool mPreTransformed;
    938 };
    939 
    940 #endif /* nsCSSRendering_h___ */