Sketch a DOM-free API for laying out and painting text

Rather than using the DOM to upload text and styling information into the
engine, this patch begins sketching a more direct API that bypasses the DOM and
CSS. Currently, this API doesn't do anything, but it's a first step.

The approach is to have a ParagraphBuilder object that can record a tree of
style interior nodes and text leaves. The build() function then applies
container-level styling information (such as TextAlign) and returns a Paragraph
object that can undergo layout and paint.

The inputs to the builder process are immutable style objects constructed from
primitive values. These primitives are currently carbon-copies of the primitive
we use in the framework today. After this patch lands, I'll convert the frame
to re-expose these values instead of re-defining them.

sky/engine/bindings/scripts/dart_types.py

@@ -128,6 +128,13 @@ CPP_SPECIAL_CONVERSION_RULES = {
     'TransferMode': 'SkXfermode::Mode',
     'FilterQuality': 'SkFilterQuality',
     'PaintingStyle': 'SkPaint::Style',
+    # TODO(abarth): Give these better C++ types.
+    'FontStyle': 'int',
+    'FontWeight': 'int',
+    'TextAlign': 'int',
+    'TextBaseline': 'int',
+    'TextDecoration': 'int',
+    'TextDecorationStyle': 'int',
 }
 
 
@@ -381,6 +388,12 @@ DART_TO_CPP_VALUE = {
     'TransferMode': pass_by_value_format('TransferMode', ''),
     'FilterQuality': pass_by_value_format('FilterQuality', ''),
     'PaintingStyle': pass_by_value_format('PaintingStyle', ''),
+    'FontStyle': pass_by_value_format('FontStyle', ''),
+    'FontWeight': pass_by_value_format('FontWeight', ''),
+    'TextAlign': pass_by_value_format('TextAlign', ''),
+    'TextBaseline': pass_by_value_format('TextBaseline', ''),
+    'TextDecoration': pass_by_value_format('TextDecoration', ''),
+    'TextDecorationStyle': pass_by_value_format('TextDecorationStyle', ''),
     'MojoDataPipeConsumer': pass_by_value_format('mojo::ScopedDataPipeConsumerHandle'),
 }
 

sky/engine/core/core.gni

@@ -625,6 +625,20 @@ sky_core_files = [
   "script/dom_dart_state.cc",
   "script/dom_dart_state.h",
   "script/monitor.h",
+  "text/FontStyle.h",
+  "text/FontWeight.h",
+  "text/Paragraph.cpp",
+  "text/Paragraph.h",
+  "text/ParagraphBuilder.cpp",
+  "text/ParagraphBuilder.h",
+  "text/ParagraphStyle.cpp",
+  "text/ParagraphStyle.h",
+  "text/TextAlign.h",
+  "text/TextBaseline.h",
+  "text/TextDecoration.h",
+  "text/TextDecorationStyle.h",
+  "text/TextStyle.cpp",
+  "text/TextStyle.h",
   "view/EventCallback.h",
   "view/FrameCallback.h",
   "view/View.cpp",
@@ -690,6 +704,10 @@ core_idl_files = get_path_info([
                                  "painting/PictureRecorder.idl",
                                  "painting/RRect.idl",
                                  "painting/Shader.idl",
+                                 "text/Paragraph.idl",
+                                 "text/ParagraphBuilder.idl",
+                                 "text/ParagraphStyle.idl",
+                                 "text/TextStyle.idl",
                                  "view/EventCallback.idl",
                                  "view/FrameCallback.idl",
                                  "view/View.idl",
@@ -712,6 +730,12 @@ core_dart_files = get_path_info([
                                   "painting/RSTransform.dart",
                                   "painting/Size.dart",
                                   "painting/TransferMode.dart",
+                                  "text/FontStyle.dart",
+                                  "text/FontWeight.dart",
+                                  "text/TextAlign.dart",
+                                  "text/TextBaseline.dart",
+                                  "text/TextDecoration.dart",
+                                  "text/TextDecorationStyle.dart",
                                 ],
                                 "abspath")
 

sky/engine/core/text/FontStyle.dart

+// 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.
+
+part of dart.sky;
+
+/// Whether to slant the glyphs in the font
+enum FontStyle {
+  /// Use the upright glyphs
+  normal,
+
+  /// Use glyphs designed for slanting
+  italic,
+
+  /// Use the upright glyphs but slant them during painting
+  oblique  // TODO(abarth): Remove. We don't really support this value.
+}

sky/engine/core/text/FontStyle.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 SKY_ENGINE_CORE_TEXT_FONTSTYLE_H_
+#define SKY_ENGINE_CORE_TEXT_FONTSTYLE_H_
+
+#include "sky/engine/tonic/dart_converter.h"
+
+namespace blink {
+
+class FontStyle {};
+
+template <>
+struct DartConverter<FontStyle>
+    : public DartConverterEnum<int> {};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_TEXT_FONTSTYLE_H_

sky/engine/core/text/FontWeight.dart

+// 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.
+
+part of dart.sky;
+
+/// The thickness of the glyphs used to draw the text
+enum FontWeight {
+  /// Thin, the least thick
+  w100,
+
+  /// Extra-light
+  w200,
+
+  /// Light
+  w300,
+
+  /// Normal / regular / plain
+  w400,
+
+  /// Medium
+  w500,
+
+  /// Semi-bold
+  w600,
+
+  /// Bold
+  w700,
+
+  /// Extra-bold
+  w800,
+
+  /// Black, the most thick
+  w900
+}

sky/engine/core/text/FontWeight.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 SKY_ENGINE_CORE_TEXT_FONTWEIGHT_H_
+#define SKY_ENGINE_CORE_TEXT_FONTWEIGHT_H_
+
+#include "sky/engine/tonic/dart_converter.h"
+
+namespace blink {
+
+class FontWeight {};
+
+template <>
+struct DartConverter<FontWeight>
+    : public DartConverterEnum<int> {};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_TEXT_FONTWEIGHT_H_

sky/engine/core/text/Paragraph.cpp

+// 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.
+
+#include "sky/engine/core/text/ParagraphBuilder.h"
+
+namespace blink {
+
+Paragraph::Paragraph()
+{
+}
+
+Paragraph::~Paragraph()
+{
+}
+
+double Paragraph::width()
+{
+    return 0.0;
+}
+
+double Paragraph::height()
+{
+    return 0.0;
+}
+
+double Paragraph::minIntrinsicWidth()
+{
+    return 0.0;
+}
+
+double Paragraph::maxIntrinsicWidth()
+{
+    return 0.0;
+}
+
+double Paragraph::alphabeticBaseline()
+{
+    return 0.0;
+}
+
+double Paragraph::ideographicBaseline()
+{
+    return 0.0;
+}
+
+void Paragraph::layout()
+{
+}
+
+void Paragraph::paint(Canvas* canvas, const Offset& offset)
+{
+}
+
+} // namespace blink

sky/engine/core/text/Paragraph.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 SKY_ENGINE_CORE_TEXT_PARAGRAPH_H_
+#define SKY_ENGINE_CORE_TEXT_PARAGRAPH_H_
+
+#include "sky/engine/tonic/dart_wrappable.h"
+#include "sky/engine/wtf/PassRefPtr.h"
+#include "sky/engine/wtf/RefCounted.h"
+#include "sky/engine/core/painting/Canvas.h"
+#include "sky/engine/core/painting/Offset.h"
+
+namespace blink {
+
+class Paragraph : public RefCounted<Paragraph>, public DartWrappable {
+    DEFINE_WRAPPERTYPEINFO();
+public:
+    static PassRefPtr<Paragraph> create() {
+      return adoptRef(new Paragraph());
+    }
+
+    ~Paragraph() override;
+
+    double minWidth() const { return m_minWidth; }
+    void setMinWidth(double value) { m_minWidth = value; }
+
+    double maxWidth() const { return m_maxWidth; }
+    void setMaxWidth(double value) { m_maxWidth = value; }
+
+    double minHeight() const { return m_minHeight; }
+    void setMinHeight(double value) { m_minHeight = value; }
+
+    double maxHeight() const { return m_maxHeight; }
+    void setMaxHeight(double value) { m_maxHeight = value; }
+
+    double width();
+    double height();
+    double minIntrinsicWidth();
+    double maxIntrinsicWidth();
+    double alphabeticBaseline();
+    double ideographicBaseline();
+
+    void layout();
+    void paint(Canvas* canvas, const Offset& offset);
+
+private:
+    double m_minWidth;
+    double m_maxWidth;
+    double m_minHeight;
+    double m_maxHeight;
+
+    explicit Paragraph();
+};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_TEXT_PARAGRAPH_H_

sky/engine/core/text/Paragraph.idl

+// 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.
+
+interface Paragraph {
+  // Inputs to layout
+  attribute double minWidth;
+  attribute double maxWidth;
+  attribute double minHeight;
+  attribute double maxHeight;
+
+  // Outputs from layout
+  readonly attribute double width;
+  readonly attribute double height;
+  readonly attribute double minIntrinsicWidth; // Intrinsic width if all wrappable points wrap.
+  readonly attribute double maxIntrinsicWidth; // Intrinsic width if no wrappable points wrap.
+  readonly attribute double alphabeticBaseline; // Distance from top to alphabetic baseline of first line
+  readonly attribute double ideographicBaseline; // Distance from top to ideographic baseline of first line
+
+  void layout();
+  void paint(Canvas canvas, Offset offset);
+};

sky/engine/core/text/ParagraphBuilder.cpp

+// 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.
+
+#include "sky/engine/core/text/ParagraphBuilder.h"
+
+namespace blink {
+
+ParagraphBuilder::ParagraphBuilder()
+{
+}
+
+ParagraphBuilder::~ParagraphBuilder()
+{
+}
+
+void ParagraphBuilder::pushStyle(TextStyle* style)
+{
+}
+
+void ParagraphBuilder::pop()
+{
+}
+
+void ParagraphBuilder::addText(const String& text)
+{
+}
+
+PassRefPtr<Paragraph> ParagraphBuilder::build(ParagraphStyle* style)
+{
+    return nullptr;
+}
+
+} // namespace blink

sky/engine/core/text/ParagraphBuilder.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 SKY_ENGINE_CORE_TEXT_PARAGRAPHBUILDER_H_
+#define SKY_ENGINE_CORE_TEXT_PARAGRAPHBUILDER_H_
+
+#include "sky/engine/core/text/Paragraph.h"
+#include "sky/engine/core/text/ParagraphStyle.h"
+#include "sky/engine/core/text/TextStyle.h"
+#include "sky/engine/tonic/dart_wrappable.h"
+#include "sky/engine/wtf/PassRefPtr.h"
+#include "sky/engine/wtf/RefCounted.h"
+
+namespace blink {
+
+class ParagraphBuilder : public RefCounted<ParagraphBuilder>, public DartWrappable {
+    DEFINE_WRAPPERTYPEINFO();
+public:
+    static PassRefPtr<ParagraphBuilder> create() {
+      return adoptRef(new ParagraphBuilder());
+    }
+
+    ~ParagraphBuilder() override;
+
+    void pushStyle(TextStyle* style);
+    void pop();
+
+    void addText(const String& text);
+
+    PassRefPtr<Paragraph> build(ParagraphStyle* style);
+
+private:
+    explicit ParagraphBuilder();
+};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_TEXT_PARAGRAPHBUILDER_H_

sky/engine/core/text/ParagraphBuilder.idl

+// 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.
+
+[
+  Constructor(),
+] interface ParagraphBuilder {
+  void pushStyle(TextStyle style);
+  void pop();
+
+  void addText(DOMString text);
+
+  Paragraph build(ParagraphStyle style);
+};

sky/engine/core/text/ParagraphStyle.cpp

+// 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.
+
+#include "sky/engine/core/text/ParagraphStyle.h"
+
+namespace blink {
+
+ParagraphStyle::ParagraphStyle(int align, double lineHeight, int textBaseline)
+{
+}
+
+ParagraphStyle::~ParagraphStyle()
+{
+}
+
+} // namespace blink

sky/engine/core/text/ParagraphStyle.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 SKY_ENGINE_CORE_TEXT_PARAGRAPHSTYLE_H_
+#define SKY_ENGINE_CORE_TEXT_PARAGRAPHSTYLE_H_
+
+#include "sky/engine/core/text/TextAlign.h"
+#include "sky/engine/core/text/TextBaseline.h"
+#include "sky/engine/tonic/dart_wrappable.h"
+#include "sky/engine/wtf/PassRefPtr.h"
+#include "sky/engine/wtf/RefCounted.h"
+
+namespace blink {
+
+class ParagraphStyle : public RefCounted<ParagraphStyle>, public DartWrappable {
+    DEFINE_WRAPPERTYPEINFO();
+public:
+    static PassRefPtr<ParagraphStyle> create(int align = 0, double lineHeight = 0.0, int textBaseline = 0) {
+      return adoptRef(new ParagraphStyle(align, lineHeight, textBaseline));
+    }
+
+    ~ParagraphStyle() override;
+
+private:
+    explicit ParagraphStyle(int align, double lineHeight, int textBaseline);
+};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_TEXT_PARAGRAPHSTYLE_H_

sky/engine/core/text/ParagraphStyle.idl

+// 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.
+
+[
+  Constructor(
+    [Named] optional TextAlign align,
+    [Named] optional double lineHeight,
+    [Named] optional TextBaseline textBaseline
+  )
+] interface ParagraphStyle {
+};

sky/engine/core/text/TextAlign.dart

+// 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.
+
+part of dart.sky;
+
+/// Whether to align text horizontally
+enum TextAlign {
+  /// Align the text on the left edge of the container
+  left,
+
+  /// Align the text on the right edge of the container
+  right,
+
+  /// Align the text in the center of the container
+  center
+}

sky/engine/core/text/TextAlign.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 SKY_ENGINE_CORE_TEXT_TEXTALIGN_H_
+#define SKY_ENGINE_CORE_TEXT_TEXTALIGN_H_
+
+#include "sky/engine/tonic/dart_converter.h"
+
+namespace blink {
+
+class TextAlign {};
+
+template <>
+struct DartConverter<TextAlign>
+    : public DartConverterEnum<int> {};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_TEXT_TEXTALIGN_H_

sky/engine/core/text/TextBaseline.dart

+// 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.
+
+part of dart.sky;
+
+/// A horizontal line used for aligning text
+enum TextBaseline {
+  // The horizontal line used to align the bottom of glyphs for alphabetic characters
+  alphabetic,
+
+  // The horizontal line used to align ideographic characters
+  ideographic
+}

sky/engine/core/text/TextBaseline.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 SKY_ENGINE_CORE_TEXT_TEXTBASELINE_H_
+#define SKY_ENGINE_CORE_TEXT_TEXTBASELINE_H_
+
+#include "sky/engine/tonic/dart_converter.h"
+
+namespace blink {
+
+class TextBaseline {};
+
+template <>
+struct DartConverter<TextBaseline>
+    : public DartConverterEnum<int> {};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_TEXT_TEXTALIGN_H_

sky/engine/core/text/TextDecoration.dart

+// 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.
+
+part of dart.sky;
+
+/// A linear decoration to draw near the text
+enum TextDecoration {
+  /// Do not draw a decoration
+  none,
+
+  /// Draw a line underneath each line of text
+  underline,
+
+  /// Draw a line above each line of text
+  overline,
+
+  /// Draw a line through each line of text
+  lineThrough
+}

sky/engine/core/text/TextDecoration.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 SKY_ENGINE_CORE_TEXT_TEXTDECORATION_H_
+#define SKY_ENGINE_CORE_TEXT_TEXTDECORATION_H_
+
+#include "sky/engine/core/rendering/style/RenderStyleConstants.h"
+#include "sky/engine/tonic/dart_converter.h"
+
+namespace blink {
+
+template <>
+struct DartConverter<TextDecoration>
+    : public DartConverterEnum<int> {};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_TEXT_TEXTDECORATION_H_

sky/engine/core/text/TextDecorationStyle.dart

+// 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.
+
+part of dart.sky;
+
+/// The style in which to draw a text decoration
+enum TextDecorationStyle {
+  /// Draw a solid line
+  solid,
+
+  /// Draw two lines
+  double,
+
+  /// Draw a dotted line
+  dotted,
+
+  /// Draw a dashed line
+  dashed,
+
+  /// Draw a sinusoidal line
+  wavy
+}

sky/engine/core/text/TextDecorationStyle.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 SKY_ENGINE_CORE_TEXT_TEXTDECORATIONSTYLE_H_
+#define SKY_ENGINE_CORE_TEXT_TEXTDECORATIONSTYLE_H_
+
+#include "sky/engine/core/rendering/style/RenderStyleConstants.h"
+#include "sky/engine/tonic/dart_converter.h"
+
+namespace blink {
+
+template <>
+struct DartConverter<TextDecorationStyle>
+    : public DartConverterEnum<int> {};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_TEXT_TEXTDECORATIONSTYLE_H_

sky/engine/core/text/TextStyle.cpp

+// 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.
+
+#include "sky/engine/core/text/TextStyle.h"
+
+namespace blink {
+
+TextStyle::TextStyle(
+    SkColor color,
+    const String& fontFamily,
+    double fontSize,
+    int fontWeight,
+    int fontStyle,
+    const Vector<int>& decoration,
+    SkColor decorationColor,
+    int decorationStyle)
+{
+}
+
+TextStyle::~TextStyle()
+{
+}
+
+} // namespace blink

sky/engine/core/text/TextStyle.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 SKY_ENGINE_CORE_TEXT_TEXTSTYLE_H_
+#define SKY_ENGINE_CORE_TEXT_TEXTSTYLE_H_
+
+#include "sky/engine/core/painting/CanvasColor.h"
+#include "sky/engine/core/text/FontStyle.h"
+#include "sky/engine/core/text/FontWeight.h"
+#include "sky/engine/core/text/TextDecoration.h"
+#include "sky/engine/core/text/TextDecorationStyle.h"
+#include "sky/engine/tonic/dart_wrappable.h"
+#include "sky/engine/wtf/PassRefPtr.h"
+#include "sky/engine/wtf/RefCounted.h"
+#include "sky/engine/wtf/Vector.h"
+
+namespace blink {
+
+class TextStyle : public RefCounted<TextStyle>, public DartWrappable {
+    DEFINE_WRAPPERTYPEINFO();
+public:
+    static PassRefPtr<TextStyle> create(
+      SkColor color = SK_ColorWHITE,
+      const String& fontFamily = nullAtom,
+      double fontSize = 0.0,
+      int fontWeight = 0,
+      int fontStyle = 0,
+      const Vector<int>& decoration = Vector<int>(),
+      SkColor decorationColor = SK_ColorWHITE,
+      int decorationStyle = 0
+    ) {
+      return adoptRef(new TextStyle(
+        color,
+        fontFamily,
+        fontSize,
+        fontWeight,
+        fontStyle,
+        decoration,
+        decorationColor,
+        decorationStyle
+      ));
+    }
+
+    ~TextStyle() override;
+
+private:
+    explicit TextStyle(
+        SkColor color,
+        const String& fontFamily,
+        double fontSize,
+        int fontWeight,
+        int fontStyle,
+        const Vector<int>& decoration,
+        SkColor decorationColor,
+        int decorationStyle
+    );
+};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_TEXT_TEXTSTYLE_H_

sky/engine/core/text/TextStyle.idl

+// 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.
+
+[
+  Constructor(
+    [Named] optional Color color,
+    [Named] optional DOMString fontFamily,
+    [Named] optional double fontSize,
+    [Named] optional FontWeight fontWeight,
+    [Named] optional FontStyle fontStyle,
+    [Named] optional sequence<TextDecoration> decoration,
+    [Named] optional Color decorationColor,
+    [Named] optional TextDecorationStyle decorationStyle
+  )
+] interface TextStyle {
+};