Create PaintChunk and begin writing code to build paint chunks.

third_party/WebKit/Source/platform/graphics/paint/PaintChunk.h

+// Copyright 2015 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 PaintChunk_h
+#define PaintChunk_h
+
+#include "platform/graphics/paint/PaintProperties.h"
+#include <iosfwd>
+
+namespace blink {
+
+// A contiguous sequence of drawings with common paint properties.
+//
+// This is expected to be owned by the paint artifact which also owns the

[pdr., 2015/10/01 00:32:48]

May want to update this, depending on the discussion below in README.md

[jbroman, 2015/10/01 18:04:20]

?

+// related drawings.
+//
+// This is a Slimming Paint v2 class.

[pdr., 2015/10/01 00:32:48]

Lets replace this with proof in the form of an assert in the ctors :)

[jbroman, 2015/10/01 18:04:20]

It seems weird to have a data object asserting the state of the world. I'll do
it if you ask again.

I have added such assertions to PaintChunker methods which modify the chunks
vector.

+struct PaintChunk {
+    PaintChunk() : beginIndex(0), endIndex(0) { }
+    PaintChunk(unsigned begin, unsigned end, const PaintProperties& props)
+        : beginIndex(begin), endIndex(end), properties(props) { }
+
+    // Index of the first drawing in this chunk.
+    unsigned beginIndex;
+
+    // Index of the first drawing not in this chunk, so that there are
+    // |endIndex - beginIndex| drawings in the chunk.
+    unsigned endIndex;
+
+    // The paint properties which apply to this chunk.
+    PaintProperties properties;
+};
+
+inline bool operator==(const PaintChunk& a, const PaintChunk& b)
+{
+    return a.beginIndex == b.beginIndex
+        && a.endIndex == b.endIndex
+        && a.properties == b.properties;
+}
+
+inline bool operator!=(const PaintChunk& a, const PaintChunk& b)
+{
+    return !(a == b);
+}
+
+// Redeclared here to avoid ODR issues.
+// See platform/testing/PaintPrinters.h.
+void PrintTo(const PaintChunk&, std::ostream*);
+
+} // namespace blink
+
+#endif // PaintChunk_h