svginlinetextbox.cpp

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/**
 * This file is part of the DOM implementation for KDE.
 *
 * Copyright (C) 2007 Rob Buis <[e-mail]>
 *           (C) 2007 Nikolas Zimmermann <[e-mail]>
 *
 * 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"

#if ENABLE(SVG)
#include "SVGInlineTextBox.h"

#include "Document.h"
#include "Editor.h"
#include "Frame.h"
#include "GraphicsContext.h"
#include "InlineFlowBox.h"
#include "Range.h"
#include "SVGPaintServer.h"
#include "SVGRootInlineBox.h"
#include "Text.h"

#include <float.h>

using std::max;

namespace WebCore {

SVGInlineTextBox::SVGInlineTextBox(RenderObject* obj)
    : InlineTextBox(obj)
    , m_height(0)
{
}

int SVGInlineTextBox::selectionTop()
{
    return m_y;
}
 
int SVGInlineTextBox::selectionHeight()
{
    return m_height;
}

SVGRootInlineBox* SVGInlineTextBox::svgRootInlineBox() const
{
    // Find associated root inline box
    InlineFlowBox* parentBox = parent();

    while (parentBox && !parentBox->isRootInlineBox())
        parentBox = parentBox->parent();

    ASSERT(parentBox);
    ASSERT(parentBox->isRootInlineBox());

    if (!parentBox->isSVGRootInlineBox())
        return 0;

    return static_cast<SVGRootInlineBox*>(parentBox);
}

float SVGInlineTextBox::calculateGlyphWidth(RenderStyle* style, int offset, int extraCharsAvailable, int& charsConsumed, String& glyphName) const
{
    ASSERT(style);
    return style->font().floatWidth(svgTextRunForInlineTextBox(textRenderer()->text()->characters() + offset, 1, style, this, 0), extraCharsAvailable, charsConsumed, glyphName);
}

float SVGInlineTextBox::calculateGlyphHeight(RenderStyle* style, int, int) const
{
    // This is just a guess, and the only purpose of this function is to centralize this hack.
    // In real-life top-top-bottom scripts this won't be enough, I fear.
    return style->font().ascent() + style->font().descent();
}

FloatRect SVGInlineTextBox::calculateGlyphBoundaries(RenderStyle* style, int offset, const SVGChar& svgChar) const
{
    const Font& font = style->font();

    // Take RTL text into account and pick right glyph width/height.
    float glyphWidth = 0.0f;

    // FIXME: account for multi-character glyphs
    int charsConsumed;
    String glyphName;
    if (direction() == LTR)
        glyphWidth = calculateGlyphWidth(style, offset, 0, charsConsumed, glyphName);
    else
        glyphWidth = calculateGlyphWidth(style, start() + end() - offset, 0, charsConsumed, glyphName);

    float x1 = svgChar.x;
    float x2 = svgChar.x + glyphWidth;

    float y1 = svgChar.y - font.ascent();
    float y2 = svgChar.y + font.descent();

    FloatRect glyphRect(x1, y1, x2 - x1, y2 - y1);

    // Take per-character transformations into account
    TransformationMatrix ctm = svgChar.characterTransform();
    if (!ctm.isIdentity())
        glyphRect = ctm.mapRect(glyphRect);

    return glyphRect;
}

// Helper class for closestCharacterToPosition()
struct SVGInlineTextBoxClosestCharacterToPositionWalker {
    SVGInlineTextBoxClosestCharacterToPositionWalker(int x, int y)
        : m_character(0)
        , m_distance(FLT_MAX)
        , m_x(x)
        , m_y(y)
        , m_offsetOfHitCharacter(0)
    {
    }

    void chunkPortionCallback(SVGInlineTextBox* textBox, int startOffset, const TransformationMatrix& chunkCtm,
                              const Vector<SVGChar>::iterator& start, const Vector<SVGChar>::iterator& end)
    {
        RenderStyle* style = textBox->textRenderer()->style();

        Vector<SVGChar>::iterator closestCharacter = 0;
        unsigned int closestOffset = UINT_MAX;

        for (Vector<SVGChar>::iterator it = start; it != end; ++it) {
            if (it->isHidden())
                continue;

            unsigned int newOffset = textBox->start() + (it - start) + startOffset;
            FloatRect glyphRect = chunkCtm.mapRect(textBox->calculateGlyphBoundaries(style, newOffset, *it));

            // Take RTL text into account and pick right glyph width/height.
            // NOTE: This offset has to be corrected _after_ calling calculateGlyphBoundaries
            if (textBox->direction() == RTL)
                newOffset = textBox->start() + textBox->end() - newOffset;

            // Calculate distances relative to the glyph mid-point. I hope this is accurate enough.
            float xDistance = glyphRect.x() + glyphRect.width() / 2.0f - m_x;
            float yDistance = glyphRect.y() - glyphRect.height() / 2.0f - m_y;

            float newDistance = sqrtf(xDistance * xDistance + yDistance * yDistance);
            if (newDistance <= m_distance) {
                m_distance = newDistance;
                closestOffset = newOffset;
                closestCharacter = it;
            }
        }

        if (closestOffset != UINT_MAX) {
            // Record current chunk, if it contains the current closest character next to the mouse.
            m_character = closestCharacter;
            m_offsetOfHitCharacter = closestOffset;
        }
    }

    SVGChar* character() const
    {
        return m_character;
    }

    int offsetOfHitCharacter() const
    {
        if (!m_character)
            return 0;

        return m_offsetOfHitCharacter;
    }

private:
    Vector<SVGChar>::iterator m_character;
    float m_distance;

    int m_x;
    int m_y;
    int m_offsetOfHitCharacter;
};

// Helper class for selectionRect()
struct SVGInlineTextBoxSelectionRectWalker {
    SVGInlineTextBoxSelectionRectWalker()
    {
    }

    void chunkPortionCallback(SVGInlineTextBox* textBox, int startOffset, const TransformationMatrix& chunkCtm,
                              const Vector<SVGChar>::iterator& start, const Vector<SVGChar>::iterator& end)
    {
        RenderStyle* style = textBox->textRenderer()->style();

        for (Vector<SVGChar>::iterator it = start; it != end; ++it) {
            if (it->isHidden())
                continue;

            unsigned int newOffset = textBox->start() + (it - start) + startOffset;
            m_selectionRect.unite(textBox->calculateGlyphBoundaries(style, newOffset, *it));
        }

        m_selectionRect = chunkCtm.mapRect(m_selectionRect);
    }

    FloatRect selectionRect() const
    {
        return m_selectionRect;
    }

private:
    FloatRect m_selectionRect;
};

SVGChar* SVGInlineTextBox::closestCharacterToPosition(int x, int y, int& offsetOfHitCharacter) const
{
    SVGRootInlineBox* rootBox = svgRootInlineBox();
    if (!rootBox)
        return 0;

    SVGInlineTextBoxClosestCharacterToPositionWalker walkerCallback(x, y);
    SVGTextChunkWalker<SVGInlineTextBoxClosestCharacterToPositionWalker> walker(&walkerCallback, &SVGInlineTextBoxClosestCharacterToPositionWalker::chunkPortionCallback);

    rootBox->walkTextChunks(&walker, this);

    offsetOfHitCharacter = walkerCallback.offsetOfHitCharacter();
    return walkerCallback.character();
}

bool SVGInlineTextBox::svgCharacterHitsPosition(int x, int y, int& closestOffsetInBox) const
{
    int offsetOfHitCharacter = 0;
    SVGChar* charAtPosPtr = closestCharacterToPosition(x, y, offsetOfHitCharacter);
    if (!charAtPosPtr)
        return false;

    SVGChar& charAtPos = *charAtPosPtr;
    RenderStyle* style = textRenderer()->style(m_firstLine);
    FloatRect glyphRect = calculateGlyphBoundaries(style, offsetOfHitCharacter, charAtPos);

    // FIXME: Why?
    if (direction() == RTL)
        offsetOfHitCharacter++;

    // The caller actually the closest offset before/after the hit char
    // closestCharacterToPosition returns us offsetOfHitCharacter.
    closestOffsetInBox = offsetOfHitCharacter;

    // FIXME: (bug 13910) This code does not handle bottom-to-top/top-to-bottom vertical text.

    // Check whether y position hits the current character 
    if (y < charAtPos.y - glyphRect.height() || y > charAtPos.y)
        return false;

    // Check whether x position hits the current character
    if (x < charAtPos.x) {
        if (closestOffsetInBox > 0 && direction() == LTR)
            return true;
        else if (closestOffsetInBox < (int) end() && direction() == RTL)
            return true;

        return false;
    }

    // Adjust the closest offset to after the char if x was after the char midpoint
    if (x >= charAtPos.x + glyphRect.width() / 2.0)
        closestOffsetInBox += direction() == RTL ? -1 : 1;