accessible/base/TextAttrs.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef nsTextAttrs_h_
#define nsTextAttrs_h_

#include "nsCOMPtr.h"
#include "nsColor.h"
#include "nsStyleConsts.h"

class nsIFrame;
class nsIPersistentProperties;
class nsIContent;
class nsDeviceContext;

namespace mozilla {
namespace a11y {

class Accessible;
class HyperTextAccessible;

/**
 * Used to expose text attributes for the hyper text accessible (see
 * HyperTextAccessible class).
 *
 * @note "invalid: spelling" text attribute is implemented entirely in
 *       HyperTextAccessible class.
 */
class TextAttrsMgr
{
public:
  /**
   * Constructor. Used to expose default text attributes.
   */
  explicit TextAttrsMgr(HyperTextAccessible* aHyperTextAcc) :
    mOffsetAcc(nullptr),  mHyperTextAcc(aHyperTextAcc),
    mOffsetAccIdx(-1), mIncludeDefAttrs(true) { }

  /**
   * Constructor. Used to expose text attributes at the given offset.
   *
   * @param aHyperTextAcc    [in] hyper text accessible text attributes are
   *                          calculated for
   * @param aIncludeDefAttrs [optional] indicates whether default text
   *                          attributes should be included into list of exposed
   *                          text attributes
   * @param oOffsetAcc       [optional] offset an accessible the text attributes
   *                          should be calculated for
   * @param oOffsetAccIdx    [optional] index in parent of offset accessible
   */
  TextAttrsMgr(HyperTextAccessible* aHyperTextAcc,
               bool aIncludeDefAttrs,
               Accessible* aOffsetAcc,
               int32_t aOffsetAccIdx) :
    mOffsetAcc(aOffsetAcc), mHyperTextAcc(aHyperTextAcc),
    mOffsetAccIdx(aOffsetAccIdx), mIncludeDefAttrs(aIncludeDefAttrs) { }

  /*
   * Return text attributes and hyper text offsets where these attributes are
   * applied. Offsets are calculated in the case of non default attributes.
   *
   * @note In the case of default attributes pointers on hyper text offsets
   *       must be skipped.
   *
   * @param aAttributes    [in, out] text attributes list
   * @param aStartHTOffset [out, optional] start hyper text offset
   * @param aEndHTOffset   [out, optional] end hyper text offset
   */
  void GetAttributes(nsIPersistentProperties* aAttributes,
                     uint32_t* aStartHTOffset = nullptr,
                     uint32_t* aEndHTOffset = nullptr);

protected:
  /**
   * Calculates range (start and end offsets) of text where the text attributes
   * are stretched. New offsets may be smaller if one of text attributes changes
   * its value before or after the given offsets.
   *
   * @param aTextAttrArray  [in] text attributes array
   * @param aAttrArrayLen   [in] text attributes array length
   * @param aStartHTOffset  [in, out] the start offset
   * @param aEndHTOffset    [in, out] the end offset
   */
  class TextAttr;
  void GetRange(TextAttr* aAttrArray[], uint32_t aAttrArrayLen,
                uint32_t* aStartOffset, uint32_t* aEndOffset);

private:
  Accessible* mOffsetAcc;
  HyperTextAccessible* mHyperTextAcc;
  int32_t mOffsetAccIdx;
  bool mIncludeDefAttrs;

protected:

  /**
   * Interface class of text attribute class implementations.
   */
  class TextAttr
  {
  public:
    /**
     * Expose the text attribute to the given attribute set.
     *
     * @param aAttributes           [in] the given attribute set
     * @param aIncludeDefAttrValue  [in] if true then attribute is exposed even
     *                               if its value is the same as default one
     */
    virtual void Expose(nsIPersistentProperties* aAttributes,
                        bool aIncludeDefAttrValue) = 0;

    /**
     * Return true if the text attribute value on the given element equals with
     * predefined attribute value.
     */
    virtual bool Equal(Accessible* aAccessible) = 0;
  };


  /**
   * Base class to work with text attributes. See derived classes below.
   */
  template<class T>
  class TTextAttr : public TextAttr
  {
  public:
    explicit TTextAttr(bool aGetRootValue) : mGetRootValue(aGetRootValue) {}

    // TextAttr
    virtual void Expose(nsIPersistentProperties* aAttributes,
                        bool aIncludeDefAttrValue) override
    {
      if (mGetRootValue) {
        if (mIsRootDefined)
          ExposeValue(aAttributes, mRootNativeValue);
        return;
      }

      if (mIsDefined) {
        if (aIncludeDefAttrValue || mRootNativeValue != mNativeValue)
          ExposeValue(aAttributes, mNativeValue);
        return;
      }

      if (aIncludeDefAttrValue && mIsRootDefined)
        ExposeValue(aAttributes, mRootNativeValue);
    }

    virtual bool Equal(Accessible* aAccessible) override
    {
      T nativeValue;
      bool isDefined = GetValueFor(aAccessible, &nativeValue);

      if (!mIsDefined && !isDefined)
        return true;

      if (mIsDefined && isDefined)
        return nativeValue == mNativeValue;

      if (mIsDefined)
        return mNativeValue == mRootNativeValue;

      return nativeValue == mRootNativeValue;
    }

  protected:

    // Expose the text attribute with the given value to attribute set.
    virtual void ExposeValue(nsIPersistentProperties* aAttributes,
                             const T& aValue) = 0;

    // Return native value for the given DOM element.
    virtual bool GetValueFor(Accessible* aAccessible, T* aValue) = 0;

    // Indicates if root value should be exposed.
    bool mGetRootValue;

    // Native value and flag indicating if the value is defined (initialized in
    // derived classes). Note, undefined native value means it is inherited
    // from root.
    MOZ_INIT_OUTSIDE_CTOR T mNativeValue;
    MOZ_INIT_OUTSIDE_CTOR bool mIsDefined;

    // Native root value and flag indicating if the value is defined  (initialized
    // in derived classes).
    MOZ_INIT_OUTSIDE_CTOR T mRootNativeValue;
    MOZ_INIT_OUTSIDE_CTOR bool mIsRootDefined;
  };


  /**
   * Class is used for the work with 'language' text attribute.
   */
  class LangTextAttr : public TTextAttr<nsString>
  {
  public:
    LangTextAttr(HyperTextAccessible* aRoot, nsIContent* aRootElm,
                 nsIContent* aElm);
    virtual ~LangTextAttr();

  protected:

    // TextAttr
    virtual bool GetValueFor(Accessible* aAccessible, nsString* aValue) override;
    virtual void ExposeValue(nsIPersistentProperties* aAttributes,
                             const nsString& aValue) override;

  private:
    nsCOMPtr<nsIContent> mRootContent;
  };


  /**
   * Class is used for the 'invalid' text attribute. Note, it calculated
   * the attribute from aria-invalid attribute only; invalid:spelling attribute
   * calculated from misspelled text in the editor is managed by
   * HyperTextAccessible and applied on top of the value from aria-invalid.
   */
  class InvalidTextAttr : public TTextAttr<uint32_t>
  {
  public:
    InvalidTextAttr(nsIContent* aRootElm, nsIContent* aElm);
    virtual ~InvalidTextAttr() { };

  protected:

    enum {
      eFalse,
      eGrammar,
      eSpelling,
      eTrue
    };

    // TextAttr
    virtual bool GetValueFor(Accessible* aAccessible, uint32_t* aValue) override;
    virtual void ExposeValue(nsIPersistentProperties* aAttributes,
                             const uint32_t& aValue) override;

  private:
    bool GetValue(nsIContent* aElm, uint32_t* aValue);
    nsIContent* mRootElm;
  };


  /**
   * Class is used for the work with 'background-color' text attribute.
   */
  class BGColorTextAttr : public TTextAttr<nscolor>
  {
  public:
    BGColorTextAttr(nsIFrame* aRootFrame, nsIFrame* aFrame);
    virtual ~BGColorTextAttr() { }

  protected:

    // TextAttr
    virtual bool GetValueFor(Accessible* aAccessible, nscolor* aValue)
      override;
    virtual void ExposeValue(nsIPersistentProperties* aAttributes,
                             const nscolor& aValue) override;

  private:
    bool GetColor(nsIFrame* aFrame, nscolor* aColor);
    nsIFrame* mRootFrame;
  };


  /**
   * Class is used for the work with 'color' text attribute.
   */
  class ColorTextAttr : public TTextAttr<nscolor>
  {
  public:
    ColorTextAttr(nsIFrame* aRootFrame, nsIFrame* aFrame);
    virtual ~ColorTextAttr() { }

  protected:

    // TTextAttr
    virtual bool GetValueFor(Accessible* aAccessible, nscolor* aValue)
      override;
    virtual void ExposeValue(nsIPersistentProperties* aAttributes,
                             const nscolor& aValue) override;
  };


  /**
   * Class is used for the work with "font-family" text attribute.
   */
  class FontFamilyTextAttr : public TTextAttr<nsString>
  {
  public:
    FontFamilyTextAttr(nsIFrame* aRootFrame, nsIFrame* aFrame);
    virtual ~FontFamilyTextAttr() { }

  protected:

    // TTextAttr
    virtual bool GetValueFor(Accessible* aAccessible, nsString* aValue)
      override;
    virtual void ExposeValue(nsIPersistentProperties* aAttributes,
                             const nsString& aValue) override;

  private:

    bool GetFontFamily(nsIFrame* aFrame, nsString& aFamily);
  };


  /**
   * Class is used for the work with "font-size" text attribute.
   */
  class FontSizeTextAttr : public TTextAttr<nscoord>
  {
  public:
    FontSizeTextAttr(nsIFrame* aRootFrame, nsIFrame* aFrame);
    virtual ~FontSizeTextAttr() { }

  protected:

    // TTextAttr
    virtual bool GetValueFor(Accessible* aAccessible, nscoord* aValue)
      override;
    virtual void ExposeValue(nsIPersistentProperties* aAttributes,
                             const nscoord& aValue) override;

  private:
    nsDeviceContext* mDC;
  };


  /**
   * Class is used for the work with "font-style" text attribute.
   */
  class FontStyleTextAttr : public TTextAttr<nscoord>
  {
  public:
    FontStyleTextAttr(nsIFrame* aRootFrame, nsIFrame* aFrame);
    virtual ~FontStyleTextAttr() { }

  protected:

    // TTextAttr
    virtual bool GetValueFor(Accessible* aContent, nscoord* aValue)
      override;
    virtual void ExposeValue(nsIPersistentProperties* aAttributes,
                             const nscoord& aValue) override;
  };


  /**
   * Class is used for the work with "font-weight" text attribute.
   */
  class FontWeightTextAttr : public TTextAttr<int32_t>
  {
  public:
    FontWeightTextAttr(nsIFrame* aRootFrame, nsIFrame* aFrame);
    virtual ~FontWeightTextAttr() { }

  protected:

    // TTextAttr
    virtual bool GetValueFor(Accessible* aAccessible, int32_t* aValue)
      override;
    virtual void ExposeValue(nsIPersistentProperties* aAttributes,
                             const int32_t& aValue) override;

  private:
    int32_t GetFontWeight(nsIFrame* aFrame);
  };

  /**
   * Class is used for the work with 'auto-generated' text attribute.
   */
  class AutoGeneratedTextAttr : public TTextAttr<bool>
  {
  public:
    AutoGeneratedTextAttr(HyperTextAccessible* aHyperTextAcc,
                          Accessible* aAccessible);
    virtual ~AutoGeneratedTextAttr() { }

  protected:
    // TextAttr
    virtual bool GetValueFor(Accessible* aAccessible, bool* aValue)
      override;
    virtual void ExposeValue(nsIPersistentProperties* aAttributes,
                             const bool& aValue) override;
  };


  /**
   * TextDecorTextAttr class is used for the work with
   * "text-line-through-style", "text-line-through-color",
   * "text-underline-style" and "text-underline-color" text attributes.
   */

  class TextDecorValue
  {
  public:
    TextDecorValue() { }
    explicit TextDecorValue(nsIFrame* aFrame);

    nscolor Color() const { return mColor; }
    uint8_t Style() const { return mStyle; }

    bool IsDefined() const
      { return IsUnderline() || IsLineThrough(); }
    bool IsUnderline() const
      { return mLine & NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE; }
    bool IsLineThrough() const
      { return mLine & NS_STYLE_TEXT_DECORATION_LINE_LINE_THROUGH; }

    bool operator ==(const TextDecorValue& aValue)
    {
      return mColor == aValue.mColor && mLine == aValue.mLine &&
        mStyle == aValue.mStyle;
    }
    bool operator !=(const TextDecorValue& aValue)
      { return !(*this == aValue); }

  private:
    nscolor mColor;
    uint8_t mLine;
    uint8_t mStyle;
  };

  class TextDecorTextAttr : public TTextAttr<TextDecorValue>
  {
  public:
    TextDecorTextAttr(nsIFrame* aRootFrame, nsIFrame* aFrame);
    virtual ~TextDecorTextAttr() { }

  protected:

    // TextAttr
    virtual bool GetValueFor(Accessible* aAccessible, TextDecorValue* aValue)
      override;
    virtual void ExposeValue(nsIPersistentProperties* aAttributes,
                             const TextDecorValue& aValue) override;
  };

  /**
   * Class is used for the work with "text-position" text attribute.
   */

  enum TextPosValue {
    eTextPosNone = 0,
    eTextPosBaseline,
    eTextPosSub,
    eTextPosSuper
  };

  class TextPosTextAttr : public TTextAttr<TextPosValue>
  {
  public:
    TextPosTextAttr(nsIFrame* aRootFrame, nsIFrame* aFrame);
    virtual ~TextPosTextAttr() { }

  protected:

    // TextAttr
    virtual bool GetValueFor(Accessible* aAccessible, TextPosValue* aValue)
      override;
    virtual void ExposeValue(nsIPersistentProperties* aAttributes,
                             const TextPosValue& aValue) override;

  private:
    TextPosValue GetTextPosValue(nsIFrame* aFrame) const;
  };

}; // TextAttrMgr

} // namespace a11y
} // namespace mozilla

#endif