characterwidget.cpp

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#include "characterwidget.h"

#include <QFontDatabase>
#include <QMouseEvent>
#include <QPainter>
#include <QRawFont>
#include <QToolTip>
#include <QtMath>

CharacterWidget::CharacterWidget(QWidget *parent) : QWidget(parent)
{
    setMouseTracking(true);
}

void CharacterWidget::init(const QString &path)
{
    const ushort max = 0xffff;
    const QRawFont rf(path, 12);
    // cost less than 10ms when contains 30k chars
    for (auto i = 0; i < max; ++i) {
        if (rf.supportsCharacter(i)) {
            m_char_indexes << i;
        }
    }
}

QPixmap CharacterWidget::getSelectedCharPix()
{
    if (m_last_key == 0) {
        return {};
    }

    const QRect rt(0, 0, m_sz_square, m_sz_square);
    QPixmap pix(rt.size());
    QPainter p(&pix);
    p.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing);
    p.fillRect(rt, QBrush(Qt::white));
    p.setFont(m_ft);
    p.setPen(QPen(Qt::black));
    p.drawText(rt, Qt::AlignCenter, QString(QChar(m_last_key)));
    return pix;
}

void CharacterWidget::updateFont(const QFont &font)
{
    m_ft        = font;
    m_sz_square = qMax(16, 4 + QFontMetrics(m_ft, this).height());
    adjustSize();
    update();
}

QSize CharacterWidget::sizeHint() const
{
    if (auto c = getCharCount()) {
        return QSize(m_columns * m_sz_square,
                     qCeil(c * 1. / m_columns) * m_sz_square);
    }
    return QSize(m_columns * m_sz_square, (65536 / m_columns) * m_sz_square);
}

ushort CharacterWidget::getCharIndexAtPos(const QPoint &pt)
{
    uint index = (pt.y() / m_sz_square) * m_columns + pt.x() / m_sz_square;
    if (index < getCharCount()) {
        return m_char_indexes[index];
    }
    return 0;
}

void CharacterWidget::mouseMoveEvent(QMouseEvent *event)
{
    ushort c = getCharIndexAtPos(event->pos());
    QString text
        = QString::fromLatin1(
              "<p>Character: <span style=\"font-size: 24pt; font-family: %1\">")
              .arg(m_ft.family())
          + QChar(c) + QString::fromLatin1("</span><p>Value: 0x")
          + QString::number(c, 16);
    QToolTip::showText(event->globalPos(), text, this);
}

void CharacterWidget::mousePressEvent(QMouseEvent *event)
{
    if (event->button() != Qt::LeftButton) {
        QWidget::mousePressEvent(event);
        return;
    }

    m_last_key = getCharIndexAtPos(event->pos());
    update();
}

void CharacterWidget::paintEvent(QPaintEvent *event)
{
    if (!m_char_indexes.size()) {
        return;
    }
    QPainter painter(this);
    painter.fillRect(event->rect(), QBrush(Qt::white));
    painter.setFont(m_ft);

    const QRect rt_redraw = event->rect();
    const int row_end     = rt_redraw.bottom() / m_sz_square;
    const int col_begin   = rt_redraw.left() / m_sz_square;
    const int col_end     = rt_redraw.right() / m_sz_square;
    const ushort char_t   = getCharCount();
    const QFontMetrics fm(m_ft);
    const QRawFont rawft = QRawFont::fromFont(m_ft);
    for (int row = rt_redraw.top() / m_sz_square; row <= row_end; ++row) {
        const int first_index_row = row * m_columns;
        for (int col = col_begin; col <= col_end; ++col) {
            const auto index = first_index_row + col;
            if (index >= char_t) {
                return;
            }
            const ushort key = m_char_indexes[index];

            painter.setPen(QPen(Qt::black));
            painter.setClipRect(col * m_sz_square, row * m_sz_square,
                                m_sz_square, m_sz_square);

            if (key == m_last_key) {
                painter.fillRect(col * m_sz_square + 1, row * m_sz_square + 1,
                                 m_sz_square, m_sz_square, QBrush("#cde8ff"));
            }

            painter.drawText(col * m_sz_square + (m_sz_square / 2)
                                 - fm.horizontalAdvance(QChar(key)) / 2,
                             row * m_sz_square + 4 + fm.ascent(),
                             QString(QChar(key)));
        }
    }
}