inlinetextbox.cpp

linux下开源浏览器WebKit的源码,市面上的很多商用浏览器都是移植自WebKit

/*
 * (C) 1999 Lars Knoll ([e-mail])
 * (C) 2000 Dirk Mueller ([e-mail])
 * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#include "config.h"
#include "InlineTextBox.h"

#include "ChromeClient.h"
#include "Document.h"
#include "Editor.h"
#include "Frame.h"
#include "GraphicsContext.h"
#include "HitTestResult.h"
#include "Page.h"
#include "RenderArena.h"
#include "RenderBlock.h"
#include "RenderTheme.h"
#include "Text.h"
#include "break_lines.h"
#include <wtf/AlwaysInline.h>

using namespace std;

namespace WebCore {

int InlineTextBox::height() const
{
    return m_treatAsText ? renderer()->style(m_firstLine)->font().height() : 0;
}

int InlineTextBox::selectionTop()
{
    return root()->selectionTop();
}

int InlineTextBox::selectionHeight()
{
    return root()->selectionHeight();
}

bool InlineTextBox::isSelected(int startPos, int endPos) const
{
    int sPos = max(startPos - m_start, 0);
    int ePos = min(endPos - m_start, (int)m_len);
    return (sPos < ePos);
}

RenderObject::SelectionState InlineTextBox::selectionState()
{
    RenderObject::SelectionState state = renderer()->selectionState();
    if (state == RenderObject::SelectionStart || state == RenderObject::SelectionEnd || state == RenderObject::SelectionBoth) {
        int startPos, endPos;
        renderer()->selectionStartEnd(startPos, endPos);
        // The position after a hard line break is considered to be past its end.
        int lastSelectable = start() + len() - (isLineBreak() ? 1 : 0);

        bool start = (state != RenderObject::SelectionEnd && startPos >= m_start && startPos < m_start + m_len);
        bool end = (state != RenderObject::SelectionStart && endPos > m_start && endPos <= lastSelectable);
        if (start && end)
            state = RenderObject::SelectionBoth;
        else if (start)
            state = RenderObject::SelectionStart;
        else if (end)
            state = RenderObject::SelectionEnd;
        else if ((state == RenderObject::SelectionEnd || startPos < m_start) &&
                 (state == RenderObject::SelectionStart || endPos > lastSelectable))
            state = RenderObject::SelectionInside;
        else if (state == RenderObject::SelectionBoth)
            state = RenderObject::SelectionNone;
    }
    return state;
}

IntRect InlineTextBox::selectionRect(int tx, int ty, int startPos, int endPos)
{
    int sPos = max(startPos - m_start, 0);
    int ePos = min(endPos - m_start, (int)m_len);
    
    if (sPos >= ePos)
        return IntRect();

    RenderText* textObj = textRenderer();
    int selTop = selectionTop();
    int selHeight = selectionHeight();
    const Font& f = textObj->style(m_firstLine)->font();

    IntRect r = enclosingIntRect(f.selectionRectForText(TextRun(textObj->text()->characters() + m_start, m_len, textObj->allowTabs(), textPos(), m_toAdd, direction() == RTL, m_dirOverride),
                                                        IntPoint(tx + m_x, ty + selTop), selHeight, sPos, ePos));
    if (r.x() > tx + m_x + m_width)
        r.setWidth(0);
    else if (r.right() - 1 > tx + m_x + m_width)
        r.setWidth(tx + m_x + m_width - r.x());
    return r;
}

void InlineTextBox::deleteLine(RenderArena* arena)
{
    toRenderText(renderer())->removeTextBox(this);
    destroy(arena);
}

void InlineTextBox::extractLine()
{
    if (m_extracted)
        return;

    toRenderText(renderer())->extractTextBox(this);
}

void InlineTextBox::attachLine()
{
    if (!m_extracted)
        return;
    
    toRenderText(renderer())->attachTextBox(this);
}

int InlineTextBox::placeEllipsisBox(bool ltr, int blockEdge, int ellipsisWidth, bool& foundBox)
{
    if (foundBox) {
        m_truncation = cFullTruncation;
        return -1;
    }

    int ellipsisX = ltr ? blockEdge - ellipsisWidth : blockEdge + ellipsisWidth;
    
    // Criteria for full truncation:
    // LTR: the left edge of the ellipsis is to the left of our text run.
    // RTL: the right edge of the ellipsis is to the right of our text run.
    bool ltrFullTruncation = ltr && ellipsisX <= m_x;
    bool rtlFullTruncation = !ltr && ellipsisX >= (m_x + m_width);
    if (ltrFullTruncation || rtlFullTruncation) {
        // Too far.  Just set full truncation, but return -1 and let the ellipsis just be placed at the edge of the box.
        m_truncation = cFullTruncation;
        foundBox = true;
        return -1;
    }

    bool ltrEllipsisWithinBox = ltr && (ellipsisX < m_x + m_width);
    bool rtlEllipsisWithinBox = !ltr && (ellipsisX > m_x);
    if (ltrEllipsisWithinBox || rtlEllipsisWithinBox) {
        if (ltr && direction() == RTL || !ltr && direction() == LTR)
            return -1; // FIXME: Support cases in which the last run's directionality differs from the context.

        foundBox = true;

        int offset = offsetForPosition(ellipsisX, false);
        if (offset == 0) {
            // No characters should be rendered.  Set ourselves to full truncation and place the ellipsis at the min of our start
            // and the ellipsis edge.
            m_truncation = cFullTruncation;
            return min(ellipsisX, m_x);
        }

        // Set the truncation index on the text run.  The ellipsis needs to be placed just after the last visible character.
        m_truncation = offset;
        if (ltr)
            return m_x + toRenderText(renderer())->width(m_start, offset, textPos(), m_firstLine);
        else
            return m_x + (m_width - toRenderText(renderer())->width(m_start, offset, textPos(), m_firstLine)) - ellipsisWidth;
    }
    return -1;
}

Color correctedTextColor(Color textColor, Color backgroundColor) 
{
    // Adjust the text color if it is too close to the background color,
    // by darkening or lightening it to move it further away.
    
    int d = differenceSquared(textColor, backgroundColor);
    // semi-arbitrarily chose 65025 (255^2) value here after a few tests; 
    if (d > 65025) {
        return textColor;
    }
    
    int distanceFromWhite = differenceSquared(textColor, Color::white);
    int distanceFromBlack = differenceSquared(textColor, Color::black);

    if (distanceFromWhite < distanceFromBlack) {
        return textColor.dark();
    }
    
    return textColor.light();
}

void updateGraphicsContext(GraphicsContext* context, const Color& fillColor, const Color& strokeColor, float strokeThickness)
{
    int mode = context->textDrawingMode();
    if (strokeThickness > 0) {
        int newMode = mode | cTextStroke;
        if (mode != newMode) {
            context->setTextDrawingMode(newMode);
            mode = newMode;
        }
    }
    
    if (mode & cTextFill && fillColor != context->fillColor())
        context->setFillColor(fillColor);

    if (mode & cTextStroke) {
        if (strokeColor != context->strokeColor())
            context->setStrokeColor(strokeColor);
        if (strokeThickness != context->strokeThickness())
            context->setStrokeThickness(strokeThickness);
    }
}

bool InlineTextBox::isLineBreak() const
{
    return renderer()->isBR() || (renderer()->style()->preserveNewline() && len() == 1 && (*textRenderer()->text())[start()] == '\n');
}

bool InlineTextBox::nodeAtPoint(const HitTestRequest&, HitTestResult& result, int x, int y, int tx, int ty)
{
    if (isLineBreak())
        return false;

    IntRect rect(tx + m_x, ty + m_y, m_width, height());
    if (m_truncation != cFullTruncation && visibleToHitTesting() && rect.contains(x, y)) {
        renderer()->updateHitTestResult(result, IntPoint(x - tx, y - ty));
        return true;
    }
    return false;
}

static void paintTextWithShadows(GraphicsContext* context, const Font& font, const TextRun& textRun, int startOffset, int endOffset, const IntPoint& textOrigin, int x, int y, int w, int h, ShadowData* shadow, bool stroked)
{
    do {
        IntSize extraOffset;

        if (shadow) {
            IntSize shadowOffset(shadow->x, shadow->y);
            int shadowBlur = shadow->blur;
            const Color& shadowColor = shadow->color;

            if (shadow->next || stroked) {
                IntRect shadowRect(x, y, w, h);
                shadowRect.inflate(shadowBlur);
                shadowRect.move(shadowOffset);
                context->save();
                context->clip(shadowRect);

                extraOffset = IntSize(0, 2 * h + max(0, shadowOffset.height()) + shadowBlur);
                shadowOffset -= extraOffset;
            }
            context->setShadow(shadowOffset, shadowBlur, shadowColor);
        }

        if (startOffset <= endOffset)
            context->drawText(font, textRun, textOrigin + extraOffset, startOffset, endOffset);
        else {
            if (endOffset > 0)
                context->drawText(font, textRun, textOrigin + extraOffset,  0, endOffset);
            if (startOffset < textRun.length())
                context->drawText(font, textRun, textOrigin + extraOffset, startOffset);
        }

        if (!shadow)
            break;

        if (shadow->next || stroked)
            context->restore();
        else
            context->clearShadow();

        shadow = shadow->next;
    } while (shadow || stroked);
}

void InlineTextBox::paint(RenderObject::PaintInfo& paintInfo, int tx, int ty)
{
    if (isLineBreak() || !renderer()->shouldPaintWithinRoot(paintInfo) || renderer()->style()->visibility() != VISIBLE ||
        m_truncation == cFullTruncation || paintInfo.phase == PaintPhaseOutline)
        return;
    
    ASSERT(paintInfo.phase != PaintPhaseSelfOutline && paintInfo.phase != PaintPhaseChildOutlines);

    int xPos = tx + m_x - parent()->maxHorizontalVisualOverflow();
    int w = width() + 2 * parent()->maxHorizontalVisualOverflow();
    if (xPos >= paintInfo.rect.right() || xPos + w <= paintInfo.rect.x())
        return;

    bool isPrinting = textRenderer()->document()->printing();
    
    // Determine whether or not we're selected.
    bool haveSelection = !isPrinting && paintInfo.phase != PaintPhaseTextClip && selectionState() != RenderObject::SelectionNone;
    if (!haveSelection && paintInfo.phase == PaintPhaseSelection)
        // When only painting the selection, don't bother to paint if there is none.
        return;

    GraphicsContext* context = paintInfo.context;

    // Determine whether or not we have composition underlines to draw.
    bool containsComposition = renderer()->node() && renderer()->document()->frame()->editor()->compositionNode() == renderer()->node();