codeeditor.cpp

/*
 * This file is part of ShaderWorkshop (https://github.com/VladimirMakeev/ShaderWorkshop).
 * Copyright (C) 2019 Vladimir Makeev.
 *
 * ShaderWorkshop is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.

 * ShaderWorkshop 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 Lesser General Public License for more details.

 * You should have received a copy of the GNU Lesser General Public License
 * along with ShaderWorkshop.  If not, see <https://www.gnu.org/licenses/>.
 */

#include "codeeditor.h"
#include "linenumberarea.h"
#include <QPainter>
#include <QTextBlock>

CodeEditor::CodeEditor(QWidget *parent) :
    QPlainTextEdit(parent),
    lineNumberArea(new LineNumberArea(this)),
    lineHighlightColor("#e9ffcc")
{
    connect(this, SIGNAL(blockCountChanged(int)),
            this, SLOT(updateLineNumberAreaWidth(int)));
    connect(this, SIGNAL(updateRequest(QRect,int)),
            this, SLOT(updateLineNumberArea(QRect,int)));
    connect(this, SIGNAL(cursorPositionChanged()),
            this, SLOT(highlightCurrentLine()));

    updateLineNumberAreaWidth(0);
    highlightCurrentLine();
}

void CodeEditor::lineNumberAreaPaintEvent(QPaintEvent *event)
{
    QPainter painter(lineNumberArea);

    painter.fillRect(event->rect(), Qt::lightGray);

    QTextBlock block = firstVisibleBlock();
    int blockNumber = block.blockNumber();
    int top = (int)blockBoundingGeometry(block).translated(contentOffset()).top();
    int bottom = top + (int)blockBoundingRect(block).height();

    while (block.isValid() && top <= event->rect().bottom()) {
        if (block.isVisible() && bottom >= event->rect().top()) {
            QString number = QString::number(blockNumber + 1);

            painter.setPen(Qt::black);
            painter.drawText(0, top, lineNumberArea->width(), fontMetrics().height(),
                             Qt::AlignRight, number);
        }

        block = block.next();
        top = bottom;
        bottom = top + (int)blockBoundingRect(block).height();
        blockNumber++;
    }
}

int CodeEditor::lineNumberAreaWidth()
{
    int digits = 1;
    int max = qMax(1, blockCount());

    while (max >= 10) {
        max /= 10;
        digits++;
    }

    int space = 5 + fontMetrics().width(QLatin1Char('9')) * digits;

    return space;
}

void CodeEditor::highlightLine(int line)
{
    QTextCursor cur(document()->findBlockByLineNumber(line - 1));

    setTextCursor(cur);
}

void CodeEditor::resizeEvent(QResizeEvent *e)
{
    QPlainTextEdit::resizeEvent(e);

    QRect cr = contentsRect();

    lineNumberArea->setGeometry(QRect(cr.left(), cr.top(), lineNumberAreaWidth(), cr.height()));
}

void CodeEditor::keyPressEvent(QKeyEvent *e)
{
    // insert 4 spaces instead of TAB
    if (e->key() == Qt::Key_Tab) {
        insertPlainText("    ");
        e->accept();
        return;
    }

    QPlainTextEdit::keyPressEvent(e);
}

void CodeEditor::updateLineNumberAreaWidth(int)
{
    setViewportMargins(lineNumberAreaWidth(), 0, 0, 0);
}

void CodeEditor::highlightCurrentLine()
{
    QList<QTextEdit::ExtraSelection> selections;

    if (!isReadOnly()) {
        QTextEdit::ExtraSelection selection;

        selection.format.setBackground(lineHighlightColor);
        selection.format.setProperty(QTextFormat::FullWidthSelection, true);
        selection.cursor = textCursor();
        selection.cursor.clearSelection();

        selections.append(selection);
    }

    setExtraSelections(selections);
}

void CodeEditor::updateLineNumberArea(const QRect &rect, int dy)
{
    if (dy) {
        lineNumberArea->scroll(0, dy);
    }
    else {
        lineNumberArea->update(0, rect.y(), lineNumberArea->width(), rect.height());
    }

    if (rect.contains(viewport()->rect())) {
        updateLineNumberAreaWidth(0);
    }
}