layout/painting/nsImageRenderer.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 nsImageRenderer_h__
   8 #define nsImageRenderer_h__
   9
  10 #include "nsStyleStruct.h"
  11 #include "Units.h"
  12 #include "mozilla/AspectRatio.h"
  13 #include "mozilla/SurfaceFromElementResult.h"
  14
  15 class gfxDrawable;
  16 class nsDisplayItem;
  17 namespace mozilla {
  18
  19 namespace layers {
  20 class StackingContextHelper;
  21 class WebRenderParentCommand;
  22 class RenderRootStateManager;
  23 }  // namespace layers
  24
  25 namespace wr {
  26 class DisplayListBuilder;
  27 class IpcResourceUpdateQueue;
  28 }  // namespace wr
  29
  30 // A CSSSizeOrRatio represents a (possibly partially specified) size for use
  31 // in computing image sizes. Either or both of the width and height might be
  32 // given. A ratio of width to height may also be given. If we at least two
  33 // of these then we can compute a concrete size, that is a width and height.
  34 struct CSSSizeOrRatio {
  35   CSSSizeOrRatio()
  36       : mWidth(0), mHeight(0), mHasWidth(false), mHasHeight(false) {}
  37
  38   bool CanComputeConcreteSize() const {
  39     return mHasWidth + mHasHeight + HasRatio() >= 2;
  40   }
  41   bool IsConcrete() const { return mHasWidth && mHasHeight; }
  42   bool HasRatio() const { return !!mRatio; }
  43   bool IsEmpty() const {
  44     return (mHasWidth && mWidth <= 0) || (mHasHeight && mHeight <= 0) ||
  45            !mRatio;
  46   }
  47
  48   // CanComputeConcreteSize must return true when ComputeConcreteSize is
  49   // called.
  50   nsSize ComputeConcreteSize() const;
  51
  52   void SetWidth(nscoord aWidth) {
  53     mWidth = aWidth;
  54     mHasWidth = true;
  55     if (mHasHeight) {
  56       mRatio = AspectRatio::FromSize(mWidth, mHeight);
  57     }
  58   }
  59   void SetHeight(nscoord aHeight) {
  60     mHeight = aHeight;
  61     mHasHeight = true;
  62     if (mHasWidth) {
  63       mRatio = AspectRatio::FromSize(mWidth, mHeight);
  64     }
  65   }
  66   void SetSize(const nsSize& aSize) {
  67     mWidth = aSize.width;
  68     mHeight = aSize.height;
  69     mHasWidth = true;
  70     mHasHeight = true;
  71     mRatio = AspectRatio::FromSize(mWidth, mHeight);
  72   }
  73   void SetRatio(const AspectRatio& aRatio) {
  74     MOZ_ASSERT(
  75         !mHasWidth || !mHasHeight,
  76         "Probably shouldn't be setting a ratio if we have a concrete size");
  77     mRatio = aRatio;
  78   }
  79
  80   AspectRatio mRatio;
  81   nscoord mWidth;
  82   nscoord mHeight;
  83   bool mHasWidth;
  84   bool mHasHeight;
  85 };
  86
  87 /**
  88  * This is a small wrapper class to encapsulate image drawing that can draw an
  89  * StyleImage image, which may internally be a real image, a sub image, or a CSS
  90  * gradient, etc...
  91  *
  92  * @note Always call the member functions in the order of PrepareImage(),
  93  * SetSize(), and Draw*().
  94  */
  95 class nsImageRenderer {
  96  public:
  97   typedef mozilla::image::ImgDrawResult ImgDrawResult;
  98   typedef mozilla::layers::LayerManager LayerManager;
  99   typedef mozilla::layers::ImageContainer ImageContainer;
 100
 101   enum {
 102     FLAG_SYNC_DECODE_IMAGES = 0x01,
 103     FLAG_PAINTING_TO_WINDOW = 0x02,
 104     FLAG_HIGH_QUALITY_SCALING = 0x04
 105   };
 106   enum FitType { CONTAIN, COVER };
 107
 108   nsImageRenderer(nsIFrame* aForFrame, const mozilla::StyleImage* aImage,
 109                   uint32_t aFlags);
 110   ~nsImageRenderer() = default;
 111   /**
 112    * Populates member variables to get ready for rendering.
 113    * @return true iff the image is ready, and there is at least a pixel to
 114    * draw.
 115    */
 116   bool PrepareImage();
 117
 118   /**
 119    * The three Compute*Size functions correspond to the sizing algorthms and
 120    * definitions from the CSS Image Values and Replaced Content spec. See
 121    * http://dev.w3.org/csswg/css-images-3/#sizing .
 122    */
 123
 124   /**
 125    * Compute the intrinsic size of the image as defined in the CSS Image Values
 126    * spec. The intrinsic size is the unscaled size which the image would ideally
 127    * like to be in app units.
 128    */
 129   mozilla::CSSSizeOrRatio ComputeIntrinsicSize();
 130
 131   /**
 132    * Computes the placement for a background image, or for the image data
 133    * inside of a replaced element.
 134    *
 135    * @param aPos The CSS <position> value that specifies the image's position.
 136    * @param aOriginBounds The box to which the tiling position should be
 137    *          relative. For background images, this should correspond to
 138    *          'background-origin' for the frame, except when painting on the
 139    *          canvas, in which case the origin bounds should be the bounds
 140    *          of the root element's frame. For a replaced element, this should
 141    *          be the element's content-box.
 142    * @param aTopLeft [out] The top-left corner where an image tile should be
 143    *          drawn.
 144    * @param aAnchorPoint [out] A point which should be pixel-aligned by
 145    *          nsLayoutUtils::DrawImage. This is the same as aTopLeft, unless
 146    *          CSS specifies a percentage (including 'right' or 'bottom'), in
 147    *          which case it's that percentage within of aOriginBounds. So
 148    *          'right' would set aAnchorPoint.x to aOriginBounds.XMost().
 149    *
 150    * Points are returned relative to aOriginBounds.
 151    */
 152   static void ComputeObjectAnchorPoint(const mozilla::Position& aPos,
 153                                        const nsSize& aOriginBounds,
 154                                        const nsSize& aImageSize,
 155                                        nsPoint* aTopLeft,
 156                                        nsPoint* aAnchorPoint);
 157
 158   /**
 159    * Compute the size of the rendered image using either the 'cover' or
 160    * 'contain' constraints (aFitType).
 161    */
 162   static nsSize ComputeConstrainedSize(
 163       const nsSize& aConstrainingSize,
 164       const mozilla::AspectRatio& aIntrinsicRatio, FitType aFitType);
 165   /**
 166    * Compute the size of the rendered image (the concrete size) where no cover/
 167    * contain constraints are given. The 'default algorithm' from the CSS Image
 168    * Values spec.
 169    */
 170   static nsSize ComputeConcreteSize(
 171       const mozilla::CSSSizeOrRatio& aSpecifiedSize,
 172       const mozilla::CSSSizeOrRatio& aIntrinsicSize,
 173       const nsSize& aDefaultSize);
 174
 175   /**
 176    * Set this image's preferred size. This will be its intrinsic size where
 177    * specified and the default size where it is not. Used as the unscaled size
 178    * when rendering the image.
 179    */
 180   void SetPreferredSize(const mozilla::CSSSizeOrRatio& aIntrinsicSize,
 181                         const nsSize& aDefaultSize);
 182
 183   /**
 184    * Draws the image to the target rendering context using
 185    * {background|mask}-specific arguments.
 186    * @see nsLayoutUtils::DrawImage() for parameters.
 187    */
 188   ImgDrawResult DrawLayer(nsPresContext* aPresContext,
 189                           gfxContext& aRenderingContext, const nsRect& aDest,
 190                           const nsRect& aFill, const nsPoint& aAnchor,
 191                           const nsRect& aDirty, const nsSize& aRepeatSize,
 192                           float aOpacity);
 193
 194   /**
 195    * Builds WebRender DisplayItems for an image using
 196    * {background|mask}-specific arguments.
 197    * @see nsLayoutUtils::DrawImage() for parameters.
 198    */
 199   ImgDrawResult BuildWebRenderDisplayItemsForLayer(
 200       nsPresContext* aPresContext, mozilla::wr::DisplayListBuilder& aBuilder,
 201       mozilla::wr::IpcResourceUpdateQueue& aResource,
 202       const mozilla::layers::StackingContextHelper& aSc,
 203       mozilla::layers::RenderRootStateManager* aManager, nsDisplayItem* aItem,
 204       const nsRect& aDest, const nsRect& aFill, const nsPoint& aAnchor,
 205       const nsRect& aDirty, const nsSize& aRepeatSize, float aOpacity);
 206
 207   /**
 208    * Draw the image to a single component of a border-image style rendering.
 209    * aFill The destination rect to be drawn into
 210    * aSrc is the part of the image to be rendered into a tile (aUnitSize in
 211    * aFill), if aSrc and the dest tile are different sizes, the image will be
 212    * scaled to map aSrc onto the dest tile.
 213    * aHFill and aVFill are the repeat patterns for the component -
 214    * NS_STYLE_BORDER_IMAGE_REPEAT_*
 215    * aUnitSize The scaled size of a single source rect (in destination coords)
 216    * aIndex identifies the component: 0 1 2
 217    *                                  3 4 5
 218    *                                  6 7 8
 219    * aSVGViewportSize The image size evaluated by default sizing algorithm.
 220    * Pass Nothing() if we can read a valid viewport size or aspect-ratio from
 221    * the drawing image directly, otherwise, pass Some() with viewport size
 222    * evaluated from default sizing algorithm.
 223    * aHasIntrinsicRatio is used to record if the source image has fixed
 224    * intrinsic ratio.
 225    */
 226   ImgDrawResult DrawBorderImageComponent(
 227       nsPresContext* aPresContext, gfxContext& aRenderingContext,
 228       const nsRect& aDirtyRect, const nsRect& aFill,
 229       const mozilla::CSSIntRect& aSrc, mozilla::StyleBorderImageRepeat aHFill,
 230       mozilla::StyleBorderImageRepeat aVFill, const nsSize& aUnitSize,
 231       uint8_t aIndex, const mozilla::Maybe<nsSize>& aSVGViewportSize,
 232       const bool aHasIntrinsicRatio);
 233
 234   /**
 235    * Draw the image to aRenderingContext which can be used to define the
 236    * float area in the presence of "shape-outside: <image>".
 237    */
 238   ImgDrawResult DrawShapeImage(nsPresContext* aPresContext,
 239                                gfxContext& aRenderingContext);
 240
 241   bool IsRasterImage();
 242   bool IsAnimatedImage();
 243
 244   /// Retrieves the image associated with this nsImageRenderer, if there is one.
 245   already_AddRefed<imgIContainer> GetImage();
 246
 247   bool IsImageContainerAvailable(layers::LayerManager* aManager,
 248                                  uint32_t aFlags);
 249   bool IsReady() const { return mPrepareResult == ImgDrawResult::SUCCESS; }
 250   ImgDrawResult PrepareResult() const { return mPrepareResult; }
 251   void SetExtendMode(mozilla::gfx::ExtendMode aMode) { mExtendMode = aMode; }
 252   void SetMaskOp(mozilla::StyleMaskMode aMaskOp) { mMaskOp = aMaskOp; }
 253   void PurgeCacheForViewportChange(
 254       const mozilla::Maybe<nsSize>& aSVGViewportSize, const bool aHasRatio);
 255   const nsSize& GetSize() const { return mSize; }
 256   mozilla::StyleImage::Tag GetType() const { return mType; }
 257   const mozilla::StyleGradient* GetGradientData() const {
 258     return mGradientData;
 259   }
 260
 261  private:
 262   /**
 263    * Draws the image to the target rendering context.
 264    * aSrc is a rect on the source image which will be mapped to aDest; it's
 265    * currently only used for gradients.
 266    *
 267    * @see nsLayoutUtils::DrawImage() for other parameters.
 268    */
 269   ImgDrawResult Draw(nsPresContext* aPresContext, gfxContext& aRenderingContext,
 270                      const nsRect& aDirtyRect, const nsRect& aDest,
 271                      const nsRect& aFill, const nsPoint& aAnchor,
 272                      const nsSize& aRepeatSize, const mozilla::CSSIntRect& aSrc,
 273                      float aOpacity = 1.0);
 274
 275   /**
 276    * Builds WebRender DisplayItems for the image.
 277    * aSrc is a rect on the source image which will be mapped to aDest; it's
 278    * currently only used for gradients.
 279    *
 280    * @see nsLayoutUtils::DrawImage() for other parameters.
 281    */
 282   ImgDrawResult BuildWebRenderDisplayItems(
 283       nsPresContext* aPresContext, mozilla::wr::DisplayListBuilder& aBuilder,
 284       mozilla::wr::IpcResourceUpdateQueue& aResources,
 285       const mozilla::layers::StackingContextHelper& aSc,
 286       mozilla::layers::RenderRootStateManager* aManager, nsDisplayItem* aItem,
 287       const nsRect& aDirtyRect, const nsRect& aDest, const nsRect& aFill,
 288       const nsPoint& aAnchor, const nsSize& aRepeatSize,
 289       const mozilla::CSSIntRect& aSrc, float aOpacity = 1.0);
 290
 291   /**
 292    * Helper method for creating a gfxDrawable from mPaintServerFrame or
 293    * mImageElementSurface.
 294    * Requires mType to be Element.
 295    * Returns null if we cannot create the drawable.
 296    */
 297   already_AddRefed<gfxDrawable> DrawableForElement(const nsRect& aImageRect,
 298                                                    gfxContext& aContext);
 299
 300   nsIFrame* mForFrame;
 301   const mozilla::StyleImage* mImage;
 302   mozilla::StyleImage::Tag mType;
 303   nsCOMPtr<imgIContainer> mImageContainer;
 304   const mozilla::StyleGradient* mGradientData;
 305   nsIFrame* mPaintServerFrame;
 306   SurfaceFromElementResult mImageElementSurface;
 307   ImgDrawResult mPrepareResult;
 308   nsSize mSize;  // unscaled size of the image, in app units
 309   uint32_t mFlags;
 310   mozilla::gfx::ExtendMode mExtendMode;
 311   mozilla::StyleMaskMode mMaskOp;
 312 };
 313
 314 }  // namespace mozilla
 315
 316 #endif /* nsImageRenderer_h__ */