Back PaintRecord with PaintOpBuffer instead of SkPicture

cc/paint/paint_op_buffer.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CC_PAINT_PAINT_OP_BUFFER_H_
+#define CC_PAINT_PAINT_OP_BUFFER_H_
+
+#include <stdint.h>
+
+#include "base/logging.h"
+#include "cc/paint/paint_canvas.h"
+#include "cc/paint/paint_export.h"
+#include "cc/paint/paint_flags.h"
+#include "third_party/skia/include/core/SkPicture.h"
+#include "third_party/skia/include/core/SkRect.h"
+#include "third_party/skia/include/core/SkTextBlob.h"
+
+// PaintOpBuffer is a reimplementation of SkLiteDL.
+// See: third_party/skia/src/core/SkLiteDL.h.
+
+namespace cc {
+
+class DisplayItemList;
+
+class ThreadsafeMatrix : public SkMatrix {
+ public:
+  ThreadsafeMatrix() : SkMatrix() { (void)getType(); }

[vmpstr, 2017/04/06 19:16:12]

I think techincally this SkMatrix is not initialized to anything, so it will be
using that to determine the type :P Probably OK?

[mtklein_C, 2017/04/06 19:58:48]

It's probably fine, but MSAN might hate you.  Might be simpler to default to
SkMatrix::I().

[enne (OOO), 2017/04/06 23:17:05]

Apparently I don't need this constructor!  Problem solved.  <_<

+  explicit ThreadsafeMatrix(const SkMatrix& matrix) : SkMatrix(matrix) {
+    (void)getType();
+  }
+};
+
+class ThreadsafePath : public SkPath {
+ public:
+  explicit ThreadsafePath(const SkPath& path) : SkPath(path) {
+    updateBoundsCache();
+  }
+};
+
+enum class PaintOpType : uint8_t {
+  Annotate,
+  ClipPath,
+  ClipRect,
+  ClipRRect,
+  Concat,
+  DrawArc,
+  DrawCircle,
+  DrawColor,
+  DrawDisplayItemList,
+  DrawDRRect,
+  DrawImage,
+  DrawImageRect,
+  DrawIRect,
+  DrawLine,
+  DrawOval,
+  DrawPath,
+  DrawPosText,
+  DrawRecord,
+  DrawRect,
+  DrawRRect,
+  DrawText,
+  DrawTextBlob,
+  Noop,
+  Restore,
+  Rotate,
+  Save,
+  SaveLayer,
+  SaveLayerAlpha,
+  Scale,
+  SetMatrix,
+  Translate,
+  LastPaintOpType = Translate,
+};
+
+struct CC_PAINT_EXPORT PaintOp {
+  uint32_t type : 8;
+  uint32_t skip : 24;
+
+  PaintOpType GetType() const { return static_cast<PaintOpType>(type); }
+
+  void Raster(SkCanvas* canvas, const SkMatrix& original_ctm) const;
+  bool IsDrawOp() const;
+
+  // Only valid for draw ops.
+  void RasterWithAlpha(SkCanvas* canvas, uint8_t alpha) const;
+
+  int CountSlowPaths() const { return 0; }
+  size_t AdditionalBytesUsed() const { return 0; }

[vmpstr, 2017/04/06 19:16:12]

Comment what "Additional" means.. like the data stuff?

[enne (OOO), 2017/04/06 23:17:05]

Like referenced sub-records and display lists.

+
+  static constexpr bool kIsDrawOp = false;
+  // If an op has |kHasPaintFlags| set to true, it must:
+  // (1) Provide a PaintFlags member called |flags|
+  // (2) Provide a RasterWithFlags function instead of a Raster function.
+  static constexpr bool kHasPaintFlags = false;
+  static SkRect kUnsetRect;
+};
+
+struct PaintOpWithData : PaintOp {
+  // Having data is just a helper for ops that have a varying amount of data and
+  // want a way to store that inline.  This is for ops that pass in a
+  // void* and a length.
+  explicit PaintOpWithData(size_t bytes) : bytes(bytes) {}
+
+  // Get data out by calling paint_op_data.  This can't be part of the class
+  // because it needs to know the size of the derived type.
+  size_t bytes;
+};
+
+template <typename T>
+const void* paint_op_data(const T* op) {
+  static_assert(std::is_convertible<T, PaintOpWithData>::value,
+                "T is not a PaintOpWithData");
+  // Arbitrary data for a PaintOp is stored after the PaintOp itself
+  // in the PaintOpBuffer.  Therefore, to access this data, it's
+  // pointer math to increment past the size of T.  Accessing the
+  // next op in the buffer is ((char*)op) + op->skip, with the data
+  // fitting between.
+  return op + 1;
+}
+
+template <typename T>
+void* paint_op_data(T* op) {
+  static_assert(std::is_convertible<T, PaintOpWithData>::value,
+                "T is not a PaintOpWithData");
+  return op + 1;
+}
+
+struct PaintOpWithDataArrayBase : PaintOpWithData {
+  // Helper class for static asserts in push functions.
+  using PaintOpWithData::PaintOpWithData;
+};
+
+template <typename T>
+struct PaintOpWithDataArray : PaintOpWithDataArrayBase {
+  // Paint op that has a T[count] and a char[bytes].
+  PaintOpWithDataArray(size_t bytes, size_t count)
+      : PaintOpWithDataArrayBase(bytes), count(count) {}
+  // Use paint_op_array to get array data.
+
+  size_t count;
+};
+
+template <typename M, typename T>
+const M* paint_op_array(const T* op) {
+  static_assert(std::is_convertible<T, PaintOpWithDataArrayBase>::value,
+                "T is not a PaintOpWithDataArray");
+  // See comment in paint_op_data.  Array data is stored after
+  // any void* data.  Memory layout here is: |op|data|array data|next op|
+  return SkTAddOffset<const M>(op + 1, op->bytes);

[vmpstr, 2017/04/06 19:16:12]

|bytes| here is the size of "data" here right? (Just confirming that I'm
understanding this correctly)

[enne (OOO), 2017/04/06 23:17:05]

Correct.

+}
+template <typename M, typename T>
+M* paint_op_array(T* op) {
+  static_assert(std::is_convertible<T, PaintOpWithDataArrayBase>::value,
+                "T is not a PaintOpWithDataArray");
+  return SkTAddOffset<M>(op + 1, op->bytes);
+}
+
+struct AnnotateOp final : PaintOp {
+  enum class AnnotationType {
+    URL,
+    LinkToDestination,
+    NamedDestination,
+  };
+
+  static constexpr PaintOpType kType = PaintOpType::Annotate;
+  AnnotateOp(PaintCanvas::AnnotationType annotation_type,
+             const SkRect& rect,
+             sk_sp<SkData> data);
+  ~AnnotateOp();
+  void Raster(SkCanvas* canvas) const;
+
+  PaintCanvas::AnnotationType annotation_type;
+  SkRect rect;
+  sk_sp<SkData> data;
+};
+
+struct ClipPathOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::ClipPath;
+  ClipPathOp(SkPath path, SkClipOp op, bool antialias)
+      : path(path), op(op), antialias(antialias) {}
+  void Raster(SkCanvas* canvas) const;
+  int CountSlowPaths() const;
+
+  ThreadsafePath path;
+  SkClipOp op;
+  bool antialias;
+};
+
+struct ClipRectOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::ClipRect;
+  ClipRectOp(const SkRect& rect, SkClipOp op, bool antialias)
+      : rect(rect), op(op), antialias(antialias) {}
+  void Raster(SkCanvas* canvas) const;
+
+  SkRect rect;
+  SkClipOp op;
+  bool antialias;
+};
+
+struct ClipRRectOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::ClipRRect;
+  ClipRRectOp(const SkRRect& rrect, SkClipOp op, bool antialias)
+      : rrect(rrect), op(op), antialias(antialias) {}
+  void Raster(SkCanvas* canvas) const;
+
+  SkRRect rrect;
+  SkClipOp op;
+  bool antialias;
+};
+
+struct ConcatOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::Concat;
+  explicit ConcatOp(const SkMatrix& matrix) : matrix(matrix) {}
+  void Raster(SkCanvas* canvas) const;
+
+  ThreadsafeMatrix matrix;
+};
+
+struct DrawArcOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawArc;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawArcOp(const SkRect& oval,
+            SkScalar start_angle,
+            SkScalar sweep_angle,
+            bool use_center,
+            const PaintFlags& flags)
+      : oval(oval),
+        start_angle(start_angle),
+        sweep_angle(sweep_angle),
+        use_center(use_center),
+        flags(flags) {}
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+
+  SkRect oval;
+  SkScalar start_angle;
+  SkScalar sweep_angle;
+  bool use_center;
+  PaintFlags flags;
+};
+
+struct DrawCircleOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawCircle;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawCircleOp(SkScalar cx,
+               SkScalar cy,
+               SkScalar radius,
+               const PaintFlags& flags)
+      : cx(cx), cy(cy), radius(radius), flags(flags) {}
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+
+  SkScalar cx;
+  SkScalar cy;
+  SkScalar radius;
+  PaintFlags flags;
+};
+
+struct DrawColorOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawColor;
+  static constexpr bool kIsDrawOp = true;
+  DrawColorOp(SkColor color, SkBlendMode mode) : color(color), mode(mode) {}
+  void Raster(SkCanvas* canvas) const;
+
+  SkColor color;
+  SkBlendMode mode;
+};
+
+struct DrawDisplayItemListOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawDisplayItemList;
+  static constexpr bool kIsDrawOp = true;
+  explicit DrawDisplayItemListOp(scoped_refptr<DisplayItemList> list);
+  ~DrawDisplayItemListOp();
+  void Raster(SkCanvas* canvas) const;
+  size_t AdditionalBytesUsed() const;
+  // TODO(enne): DisplayItemList should know number of slow paths.
+
+  scoped_refptr<DisplayItemList> list;
+};
+
+struct DrawDRRectOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawDRRect;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawDRRectOp(const SkRRect& outer,
+               const SkRRect& inner,
+               const PaintFlags& flags)
+      : outer(outer), inner(inner), flags(flags) {}
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+
+  SkRRect outer;
+  SkRRect inner;
+  PaintFlags flags;
+};
+
+struct DrawImageOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawImage;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawImageOp(sk_sp<const SkImage> image,
+              SkScalar left,
+              SkScalar top,
+              const PaintFlags* flags);
+  ~DrawImageOp();
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+
+  sk_sp<const SkImage> image;
+  SkScalar left;
+  SkScalar top;
+  PaintFlags flags;
+};
+
+struct DrawImageRectOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawImageRect;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawImageRectOp(sk_sp<const SkImage> image,
+                  const SkRect& src,
+                  const SkRect& dst,
+                  const PaintFlags* flags,
+                  PaintCanvas::SrcRectConstraint constraint);
+  ~DrawImageRectOp();
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+
+  sk_sp<const SkImage> image;
+  PaintFlags flags;
+  SkRect src;
+  SkRect dst;
+  PaintCanvas::SrcRectConstraint constraint;
+};
+
+struct DrawIRectOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawIRect;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawIRectOp(const SkIRect& rect, const PaintFlags& flags)
+      : rect(rect), flags(flags) {}
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+
+  SkIRect rect;
+  PaintFlags flags;
+};
+
+struct DrawLineOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawLine;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawLineOp(SkScalar x0,
+             SkScalar y0,
+             SkScalar x1,
+             SkScalar y1,
+             const PaintFlags& flags)
+      : x0(x0), y0(y0), x1(x1), y1(y1), flags(flags) {}
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+  int CountSlowPaths() const;
+
+  SkScalar x0;
+  SkScalar y0;
+  SkScalar x1;
+  SkScalar y1;
+  PaintFlags flags;
+};
+
+struct DrawOvalOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawOval;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawOvalOp(const SkRect& oval, const PaintFlags& flags)
+      : oval(oval), flags(flags) {}
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+
+  SkRect oval;
+  PaintFlags flags;
+};
+
+struct DrawPathOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawPath;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawPathOp(const SkPath& path, const PaintFlags& flags)
+      : path(path), flags(flags) {}
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+  int CountSlowPaths() const;
+
+  ThreadsafePath path;
+  PaintFlags flags;
+};
+
+struct DrawPosTextOp final : PaintOpWithDataArray<SkPoint> {
+  static constexpr PaintOpType kType = PaintOpType::DrawPosText;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawPosTextOp(size_t bytes, size_t count, const PaintFlags& flags);
+  ~DrawPosTextOp();
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+
+  PaintFlags flags;
+};
+
+struct DrawRecordOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawRecord;
+  static constexpr bool kIsDrawOp = true;
+  explicit DrawRecordOp(sk_sp<const PaintRecord> record);
+  ~DrawRecordOp();
+  void Raster(SkCanvas* canvas) const;
+  size_t AdditionalBytesUsed() const;
+
+  sk_sp<const PaintRecord> record;
+};
+
+struct DrawRectOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawRect;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawRectOp(const SkRect& rect, const PaintFlags& flags)
+      : rect(rect), flags(flags) {}
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+
+  SkRect rect;
+  PaintFlags flags;
+};
+
+struct DrawRRectOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawRRect;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawRRectOp(const SkRRect& rrect, const PaintFlags& flags)
+      : rrect(rrect), flags(flags) {}
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+
+  SkRRect rrect;
+  PaintFlags flags;
+};
+
+struct DrawTextOp final : PaintOpWithData {
+  static constexpr PaintOpType kType = PaintOpType::DrawText;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawTextOp(size_t bytes, SkScalar x, SkScalar y, const PaintFlags& flags)
+      : PaintOpWithData(bytes), x(x), y(y), flags(flags) {}
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+
+  SkScalar x;
+  SkScalar y;
+  PaintFlags flags;
+};
+
+struct DrawTextBlobOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::DrawTextBlob;
+  static constexpr bool kIsDrawOp = true;
+  static constexpr bool kHasPaintFlags = true;
+  DrawTextBlobOp(sk_sp<SkTextBlob> blob,
+                 SkScalar x,
+                 SkScalar y,
+                 const PaintFlags& flags);
+  ~DrawTextBlobOp();
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+
+  sk_sp<SkTextBlob> blob;
+  SkScalar x;
+  SkScalar y;
+  PaintFlags flags;
+};
+
+struct NoopOp final : PaintOp {

[vmpstr, 2017/04/06 19:16:12]

:D

[enne (OOO), 2017/04/06 23:17:05]

I know, I know.  NoOp just looked weird as an alternative, and even then is its
type just "No"??

Sorry :C

+  static constexpr PaintOpType kType = PaintOpType::Noop;
+  void Raster(SkCanvas* canvas) const {}
+};
+
+struct RestoreOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::Restore;
+  void Raster(SkCanvas* canvas) const;
+};
+
+struct RotateOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::Rotate;
+  explicit RotateOp(SkScalar degrees) : degrees(degrees) {}
+  void Raster(SkCanvas* canvas) const;
+
+  SkScalar degrees;
+};
+
+struct SaveOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::Save;
+  void Raster(SkCanvas* canvas) const;
+};
+
+struct SaveLayerOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::SaveLayer;
+  static constexpr bool kHasPaintFlags = true;
+  SaveLayerOp(const SkRect* bounds, const PaintFlags* flags)
+      : bounds(bounds ? *bounds : kUnsetRect) {
+    if (flags)
+      this->flags = *flags;
+  }
+  void RasterWithFlags(SkCanvas* canvas, const PaintFlags& flags) const;
+
+  SkRect bounds;
+  PaintFlags flags;
+};
+
+struct SaveLayerAlphaOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::SaveLayerAlpha;
+  SaveLayerAlphaOp(const SkRect* bounds, uint8_t alpha)
+      : bounds(bounds ? *bounds : kUnsetRect), alpha(alpha) {}
+  void Raster(SkCanvas* canvas) const;
+
+  SkRect bounds;
+  uint8_t alpha;
+};
+
+struct ScaleOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::Scale;
+  ScaleOp(SkScalar sx, SkScalar sy) : sx(sx), sy(sy) {}
+  void Raster(SkCanvas* canvas) const;
+
+  SkScalar sx;
+  SkScalar sy;
+};
+
+struct SetMatrixOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::SetMatrix;
+  explicit SetMatrixOp(const SkMatrix& matrix) : matrix(matrix) {}
+  // This is the only op that needs the original matrix.

[vmpstr, 2017/04/06 19:16:12]

Can you comment on what original means here? Does this also mean that this op is
kind of uncacheable (since adding/removing items before this one affects this
one?)

[mtklein_C, 2017/04/06 19:58:48]

When you record a setMatrix(), you're doing it in the context of the space the
recording started in (think, identity matrix).

When you play back a setMatrix(), in order to get the same effect as setMatrix()
in that record-time identity space, you need to take the matrix you recorded and
concatenate it with the matrix of the destination canvas at the time you started
playing back the recording.

So, let's say you recorded a setMatrix() to [1 0 20, 0 1 20, 0 0 1]  (identity
translated +20,+20).  Let's say the canvas you're playing back to started
translated +10,+10, i.e. [1 0 10, 0 1 10, 0 0 1].  You want to end up with a
matrix [1 0 30, 0 1 30, 0 0 1] after you play back the setMatrix(), not [1 0 20,
0 1 20, 0 0 1].

[vmpstr, 2017/04/06 20:37:47]

Hmm ok. I guess my question is then if we try and modify a previous item that
translated it to +10, +10 in your example, then that means it affects future
items like this set matrix. I don't think it matters for const records as it is
now, but it might affect any plans we might have for making this modifiable
(although I think we might run into other issues if we try that)

[vmpstr, 2017/04/06 20:40:50]

Oh sorry, I completely misunderstood that this is at raster, not at record time.
Disregard me :P

+  // TODO(enne): Find some cleaner way to do this?
+  void Raster(SkCanvas* canvas, const SkMatrix& original_ctm) const;
+
+  ThreadsafeMatrix matrix;
+};
+
+struct TranslateOp final : PaintOp {
+  static constexpr PaintOpType kType = PaintOpType::Translate;
+  TranslateOp(SkScalar dx, SkScalar dy) : dx(dx), dy(dy) {}
+  void Raster(SkCanvas* canvas) const;
+
+  SkScalar dx;
+  SkScalar dy;
+};
+
+using LargestPaintOp = DrawDRRectOp;

[vmpstr, 2017/04/06 19:16:12]

Is there a way to make this future proof?

[enne (OOO), 2017/04/06 23:17:05]

There's static asserts that tell you which op is bigger if you break this.  Is
that future proof enough for you?

+
+class CC_PAINT_EXPORT PaintOpBuffer : public SkRefCnt {
+ public:
+  enum { kPageSize = 4096 };
+
+  PaintOpBuffer();
+  explicit PaintOpBuffer(const SkRect& cull_rect);
+  ~PaintOpBuffer() override;
+
+  void Reset();
+
+  void playback(SkCanvas* canvas) const;
+  void playback(SkCanvas* canvas, SkPicture::AbortCallback* callback) const;
+
+  // TODO(enne): These are no longer approximate.  Rename these.

[vmpstr, 2017/04/06 19:16:12]

Cool! You can then ignore my previous comment about adding a comment

+  int approximateOpCount() const { return op_count_; }
+  size_t approximateBytesUsed() const {
+    return sizeof(*this) + reserved_ + subrecord_bytes_used_;
+  }
+  int numSlowPaths() const { return num_slow_paths_; }
+
+  const SkRect& cullRect() const { return cull_rect_; }
+
+  PaintOp* GetFirstOp() const {
+    return reinterpret_cast<PaintOp*>(const_cast<char*>(&first_op_[0]));
+  }
+
+  template <typename T, typename... Args>
+  void push(Args&&... args) {
+    static_assert(std::is_convertible<T, PaintOp>::value, "T not a PaintOp.");
+    static_assert(!std::is_convertible<T, PaintOpWithData>::value,
+                  "Type needs to use push_with_data");
+    push_internal<T>(0, std::forward<Args>(args)...);
+  }
+
+  template <typename T, typename... Args>
+  void push_with_data(const void* data, size_t bytes, Args&&... args) {
+    static_assert(std::is_convertible<T, PaintOpWithData>::value,
+                  "T is not a PaintOpWithData");
+#if !defined(OS_CHROMEOS)
+    // TODO(enne): non-linux chromeos builds think that DrawTextOp
+    // can be converted to a PaintOpWithDataArrayBase.  OOPS.
+    static_assert(!std::is_convertible<T, PaintOpWithDataArrayBase>::value,
+                  "Type needs to use push_with_data_array");
+#endif
+    DCHECK_GE(bytes, 0u);
+    T* op = push_internal<T>(bytes, bytes, std::forward<Args>(args)...);
+    memcpy(paint_op_data(op), data, bytes);
+
+#if DCHECK_IS_ON()
+    // Double check the data fits between op and next op and doesn't clobber.
+    char* op_start = reinterpret_cast<char*>(op);
+    char* op_end = op_start + sizeof(T);
+    char* next_op = op_start + op->skip;
+    char* data_start = reinterpret_cast<char*>(paint_op_data(op));
+    char* data_end = data_start + bytes;
+    DCHECK_GE(data_start, op_end);
+    DCHECK_LT(data_start, next_op);
+    DCHECK_LE(data_end, next_op);
+#endif
+  }
+
+  template <typename T, typename M, typename... Args>
+  void push_with_data_array(const void* data,
+                            size_t bytes,
+                            const M* array,
+                            size_t count,
+                            Args&&... args) {
+    static_assert(std::is_convertible<T, PaintOpWithDataArray<M>>::value,
+                  "T is not a PaintOpWithDataArray");
+    DCHECK_GE(bytes, 0u);
+    DCHECK_GE(count, 0u);
+    size_t array_size = sizeof(M) * count;
+    size_t total_size = bytes + array_size;
+    T* op =
+        push_internal<T>(total_size, bytes, count, std::forward<Args>(args)...);
+    memcpy(paint_op_data(op), data, bytes);
+    memcpy(paint_op_array<M>(op), array, array_size);
+
+#if DCHECK_IS_ON()
+    // Double check data and array don't clobber op, next op, or each other
+    char* op_start = reinterpret_cast<char*>(op);
+    char* op_end = op_start + sizeof(T);
+    char* next_op = op_start + op->skip;
+    char* data_start = reinterpret_cast<char*>(paint_op_data(op));
+    char* data_end = data_start + bytes;
+    char* array_start = reinterpret_cast<char*>(paint_op_array<M>(op));
+    char* array_end = array_start + array_size;
+    DCHECK_GE(data_start, op_end);
+    DCHECK_LE(data_start, array_start);
+    DCHECK_GE(array_start, data_end);
+    DCHECK_LE(array_end, next_op);
+#endif
+  }
+
+  class Iterator {
+   public:
+    explicit Iterator(const PaintOpBuffer* buffer)
+        : buffer_(buffer), ptr_(buffer_->data_.get()) {}
+
+    PaintOp* operator->() const {
+      return op_idx_ ? reinterpret_cast<PaintOp*>(ptr_) : buffer_->GetFirstOp();
+    }
+    PaintOp* operator*() const { return operator->(); }
+    Iterator begin() { return Iterator(buffer_, buffer_->data_.get(), 0); }
+    Iterator end() {
+      return Iterator(buffer_, buffer_->data_.get() + buffer_->used_,
+                      buffer_->approximateOpCount());
+    }
+    bool operator!=(const Iterator& other) {
+      // Not valid to compare iterators on different buffers.
+      DCHECK_EQ(other.buffer_, buffer_);
+      return other.op_idx_ != op_idx_;
+    }
+    Iterator& operator++() {
+      if (!op_idx_++)
+        return *this;
+      PaintOp* op = **this;
+      uint32_t type = op->type;
+      CHECK_LE(type, static_cast<uint32_t>(PaintOpType::LastPaintOpType));
+      ptr_ += op->skip;
+      return *this;
+    }
+    operator bool() const { return op_idx_ < buffer_->approximateOpCount(); }
+
+    // Return the next op without advancing the iterator, or nullptr if none.
+    PaintOp* peek1() const {
+      if (op_idx_ + 1 >= buffer_->approximateOpCount())
+        return nullptr;
+      if (!op_idx_)
+        return reinterpret_cast<PaintOp*>(ptr_);
+      return reinterpret_cast<PaintOp*>(ptr_ + (*this)->skip);
+    }
+
+    // Return the op two ops ahead without advancing the iterator, or nullptr if
+    // none.
+    PaintOp* peek2() const {
+      if (op_idx_ + 2 >= buffer_->approximateOpCount())
+        return nullptr;
+      char* next = ptr_ + (*this)->skip;
+      PaintOp* next_op = reinterpret_cast<PaintOp*>(next);
+      if (!op_idx_)
+        return next_op;
+      return reinterpret_cast<PaintOp*>(next + next_op->skip);
+    }
+
+   private:
+    Iterator(const PaintOpBuffer* buffer, char* ptr, int op_idx)
+        : buffer_(buffer), ptr_(ptr), op_idx_(op_idx) {}
+
+    const PaintOpBuffer* buffer_;

[vmpstr, 2017/04/06 19:16:12]

= nullptr for consistency?

+    char* ptr_;
+    int op_idx_ = 0;
+  };
+
+ private:
+  template <typename T, bool HasFlags>
+  struct CountSlowPathsFromFlags {
+    static int Count(const T* op) { return 0; }
+  };
+
+  template <typename T>
+  struct CountSlowPathsFromFlags<T, true> {
+    static int Count(const T* op) { return op->flags.getPathEffect() ? 1 : 0; }
+  };
+
+  template <typename T, typename... Args>
+  T* push_internal(size_t bytes, Args&&... args) {
+    size_t skip = SkAlignPtr(sizeof(T) + bytes);
+    DCHECK_LT(skip, static_cast<size_t>(1) << 24);
+    if (used_ + skip > reserved_ || !op_count_) {
+      if (!op_count_) {
+        if (bytes) {
+          // Internal first_op buffer doesn't have room for extra data.
+          // If the op wants extra bytes, then we'll just store a Noop
+          // in the first_op and proceed from there.  This seems unlikely
+          // to be a common case.
+          push<NoopOp>();
+        } else {
+          T* op = reinterpret_cast<T*>(&first_op_[0]);
+          new (op) T{std::forward<Args>(args)...};
+          op->type = static_cast<uint32_t>(T::kType);
+          op->skip = 0;
+          op_count_++;
+          return op;
+        }
+      }
+
+      static_assert(SkIsPow2(kPageSize),
+                    "This math needs updating for non-pow2.");
+      // Next greater multiple of kPageSize.
+      reserved_ = (used_ + skip + kPageSize) & ~(kPageSize - 1);
+      data_.realloc(reserved_);
+    }
+    DCHECK_LE(used_ + skip, reserved_);
+
+    T* op = reinterpret_cast<T*>(data_.get() + used_);
+    used_ += skip;
+    new (op) T(std::forward<Args>(args)...);
+    op->type = static_cast<uint32_t>(T::kType);
+    op->skip = skip;
+    op_count_++;
+
+    num_slow_paths_ += CountSlowPathsFromFlags<T, T::kHasPaintFlags>::Count(op);
+    num_slow_paths_ += op->CountSlowPaths();
+
+    subrecord_bytes_used_ += op->AdditionalBytesUsed();
+
+    return op;
+  }
+
+  char first_op_[sizeof(LargestPaintOp)];
+  SkAutoTMalloc<char> data_;
+  size_t used_ = 0;
+  size_t reserved_ = 0;
+  int op_count_ = 0;
+
+  // Record paths for veto-to-msaa for gpu raster.
+  int num_slow_paths_ = 0;
+  // Record additional bytes used by referenced sub-records and display lists.
+  size_t subrecord_bytes_used_ = 0;
+  SkRect cull_rect_;
+
+  DISALLOW_COPY_AND_ASSIGN(PaintOpBuffer);
+};
+
+}  // namespace cc
+
+#endif  // CC_PAINT_PAINT_OP_BUFFER_H_