layout/painting/nsCSSRenderingGradients.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 #ifndef nsCSSRenderingGradients_h__
   8 #define nsCSSRenderingGradients_h__
   9
  10 #include "gfxRect.h"
  11 #include "nsStyleStruct.h"
  12 #include "Units.h"
  13 #include "mozilla/Maybe.h"
  14 #include "mozilla/gfx/2D.h"
  15 #include "mozilla/webrender/webrender_ffi.h"
  16
  17 class gfxPattern;
  18
  19 namespace mozilla {
  20
  21 namespace layers {
  22 class StackingContextHelper;
  23 }  // namespace layers
  24
  25 namespace wr {
  26 class DisplayListBuilder;
  27 }  // namespace wr
  28
  29 // A resolved color stop, with a specific position along the gradient line and
  30 // a color.
  31 struct ColorStop {
  32   ColorStop() : mPosition(0), mIsMidpoint(false) {}
  33   ColorStop(double aPosition, bool aIsMidPoint,
  34             const StyleAbsoluteColor& aColor)
  35       : mPosition(aPosition), mIsMidpoint(aIsMidPoint), mColor(aColor) {}
  36   double mPosition;  // along the gradient line; 0=start, 1=end
  37   bool mIsMidpoint;
  38   StyleAbsoluteColor mColor;
  39 };
  40
  41 class nsCSSGradientRenderer final {
  42  public:
  43   /**
  44    * Prepare a nsCSSGradientRenderer for a gradient for an element.
  45    * aIntrinsicSize - the size of the source gradient.
  46    */
  47   static nsCSSGradientRenderer Create(nsPresContext* aPresContext,
  48                                       ComputedStyle* aComputedStyle,
  49                                       const StyleGradient& aGradient,
  50                                       const nsSize& aIntrinsiceSize);
  51
  52   /**
  53    * Draw the gradient to aContext
  54    * aDest - where the first tile of gradient is
  55    * aFill - the area to be filled with tiles of aDest
  56    * aSrc - the area of the gradient that will fill aDest
  57    * aRepeatSize - the distance from the origin of a tile
  58    *               to the next origin of a tile
  59    * aDirtyRect - pixels outside of this area may be skipped
  60    */
  61   void Paint(gfxContext& aContext, const nsRect& aDest, const nsRect& aFill,
  62              const nsSize& aRepeatSize, const mozilla::CSSIntRect& aSrc,
  63              const nsRect& aDirtyRect, float aOpacity = 1.0);
  64
  65   /**
  66    * Collect the gradient parameters
  67    */
  68   void BuildWebRenderParameters(float aOpacity, wr::ExtendMode& aMode,
  69                                 nsTArray<wr::GradientStop>& aStops,
  70                                 LayoutDevicePoint& aLineStart,
  71                                 LayoutDevicePoint& aLineEnd,
  72                                 LayoutDeviceSize& aGradientRadius,
  73                                 LayoutDevicePoint& aGradientCenter,
  74                                 float& aGradientAngle);
  75
  76   /**
  77    * Build display items for the gradient
  78    * aLayer - the layer to make this display item relative to
  79    * aDest - where the first tile of gradient is
  80    * aFill - the area to be filled with tiles of aDest
  81    * aRepeatSize - the distance from the origin of a tile
  82    *               to the next origin of a tile
  83    * aSrc - the area of the gradient that will fill aDest
  84    */
  85   void BuildWebRenderDisplayItems(wr::DisplayListBuilder& aBuilder,
  86                                   const layers::StackingContextHelper& aSc,
  87                                   const nsRect& aDest, const nsRect& aFill,
  88                                   const nsSize& aRepeatSize,
  89                                   const mozilla::CSSIntRect& aSrc,
  90                                   bool aIsBackfaceVisible,
  91                                   float aOpacity = 1.0);
  92
  93  private:
  94   nsCSSGradientRenderer()
  95       : mPresContext(nullptr),
  96         mGradient(nullptr),
  97         mRadiusX(0.0),
  98         mRadiusY(0.0),
  99         mAngle(0.0) {}
 100
 101   /**
 102    * Attempts to paint the tiles for a gradient by painting it once to an
 103    * offscreen surface and then painting that offscreen surface with
 104    * ExtendMode::Repeat to cover all tiles.
 105    *
 106    * Returns false if the optimization wasn't able to be used, in which case
 107    * a fallback should be used.
 108    */
 109   bool TryPaintTilesWithExtendMode(
 110       gfxContext& aContext, gfxPattern* aGradientPattern, nscoord aXStart,
 111       nscoord aYStart, const gfxRect& aDirtyAreaToFill, const nsRect& aDest,
 112       const nsSize& aRepeatSize, bool aForceRepeatToCoverTiles);
 113
 114   nsPresContext* mPresContext;
 115   const StyleGradient* mGradient;
 116   nsTArray<ColorStop> mStops;
 117   gfxPoint mLineStart, mLineEnd;  // only for linear/radial gradients
 118   double mRadiusX, mRadiusY;      // only for radial gradients
 119   gfxPoint mCenter;               // only for conic gradients
 120   float mAngle;                   // only for conic gradients
 121 };
 122
 123 }  // namespace mozilla
 124
 125 #endif /* nsCSSRenderingGradients_h__ */