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