WEBKIT中，computeAndSetTypingStyle方法不明白

void Editor::computeAndSetTypingStyle(CSSStyleDeclaration* style, EditAction editingAction)
{
    if (!style || !style->length()) {
        m_frame->selection()->clearTypingStyle();
        return;
    }

    // Calculate the current typing style.
    RefPtr<EditingStyle> typingStyle;
    if (m_frame->selection()->typingStyle()) {
        typingStyle = m_frame->selection()->typingStyle()->copy();
        typingStyle->overrideWithStyle(style->makeMutable().get());
    } else
        typingStyle = EditingStyle::create(style);

    typingStyle->prepareToApplyAt(m_frame->selection()->selection().visibleStart().deepEquivalent(), EditingStyle::PreserveWritingDirection);

    // Handle block styles, substracting these from the typing style.
    RefPtr<EditingStyle> blockStyle = typingStyle->extractAndRemoveBlockProperties();
    if (!blockStyle->isEmpty())
        applyCommand(ApplyStyleCommand::create(m_frame->document(), blockStyle.get(), editingAction));

    // Set the remaining style as the typing style.
    m_frame->selection()->setTypingStyle(typingStyle);
}

附上源码，位于webcore/editing/Editor.cpp里面，大概了解了这个方法是处理光标处输入字符时的样式，有哪位高手能详解一下 --------------------编程问答-------------------- 看看帮助文档啊

补充：移动开发 ,  Qt