136 lines
3.6 KiB
C++
136 lines
3.6 KiB
C++
#include "scrolltext.h"
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ScrollText::ScrollText(QWidget *parent) : QWidget(parent), scrollPos(0)
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{
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staticText.setTextFormat(Qt::PlainText);
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// setFixedHeight(fontMetrics().height()*2); //The theme sets this
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leftMargin = height() / 3;
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setSeparator(" --- ");
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connect(&timer, SIGNAL(timeout()), this, SLOT(timer_timeout()));
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timer.setInterval(50);
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}
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QString ScrollText::text() const { return _text; }
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void ScrollText::setText(QString text)
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{
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_text = text;
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updateText();
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update();
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}
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QString ScrollText::separator() const { return _separator; }
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void ScrollText::setSeparator(QString separator)
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{
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_separator = separator;
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updateText();
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update();
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}
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void ScrollText::updateText()
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{
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timer.stop();
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#if QT_VERSION > QT_VERSION_CHECK(5, 11, 0)
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singleTextWidth = fontMetrics().horizontalAdvance(_text);
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#else
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singleTextWidth = fontMetrics().boundingRect(_text).width();
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#endif
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scrollEnabled = (singleTextWidth > width() - leftMargin * 2);
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if (scrollEnabled) {
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scrollPos = -64;
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staticText.setText(_text + _separator);
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timer.start();
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}
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else
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staticText.setText(_text);
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staticText.prepare(QTransform(), font());
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#if QT_VERSION > QT_VERSION_CHECK(5, 11, 0)
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wholeTextSize = QSize(fontMetrics().horizontalAdvance(staticText.text()),
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fontMetrics().height());
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#else
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wholeTextSize = QSize(fontMetrics().boundingRect(staticText.text()).width(),
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fontMetrics().height());
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#endif
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}
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void ScrollText::paintEvent(QPaintEvent *)
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{
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QPainter p(this);
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if (scrollEnabled) {
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buffer.fill(qRgba(0, 0, 0, 0));
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QPainter pb(&buffer);
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pb.setPen(p.pen());
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pb.setFont(p.font());
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int x = qMin(-scrollPos, 0) + leftMargin;
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while (x < width()) {
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pb.drawStaticText(QPointF(x, (height() - wholeTextSize.height()) / 2),
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staticText);
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x += wholeTextSize.width();
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}
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// Apply Alpha Channel
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pb.setCompositionMode(QPainter::CompositionMode_DestinationIn);
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pb.setClipRect(width() - 15, 0, 15, height());
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pb.drawImage(0, 0, alphaChannel);
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pb.setClipRect(0, 0, 15, height());
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// initial situation: don't apply alpha channel in the left half of the
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// image at all; apply it more and more until scrollPos gets positive
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if (scrollPos < 0)
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pb.setOpacity(static_cast<qreal>((qMax(-8, scrollPos) + 8) / 8.0));
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pb.drawImage(0, 0, alphaChannel);
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// pb.end();
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p.drawImage(0, 0, buffer);
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}
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else {
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p.drawStaticText(
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QPointF(leftMargin, (height() - wholeTextSize.height()) / 2),
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staticText);
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}
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}
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void ScrollText::resizeEvent(QResizeEvent *)
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{
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// When the widget is resized, we need to update the alpha channel.
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alphaChannel = QImage(size(), QImage::Format_ARGB32_Premultiplied);
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buffer = QImage(size(), QImage::Format_ARGB32_Premultiplied);
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// Create Alpha Channel:
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if (width() > 64) {
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// create first scanline
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QRgb *scanline1 = reinterpret_cast<QRgb *>(alphaChannel.scanLine(0));
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for (int x = 1; x < 16; ++x)
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scanline1[x - 1] = scanline1[width() - x] = qRgba(0, 0, 0, x << 4);
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for (int x = 15; x < width() - 15; ++x)
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scanline1[x] = qRgb(0, 0, 0);
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// copy scanline to the other ones
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for (int y = 1; y < height(); ++y)
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memcpy(alphaChannel.scanLine(y), scanline1,
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static_cast<uint>(width() * 4));
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}
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else
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alphaChannel.fill(qRgb(0, 0, 0));
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// Update scrolling state
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bool newScrollEnabled = (singleTextWidth > width() - leftMargin);
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if (newScrollEnabled != scrollEnabled)
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updateText();
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}
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void ScrollText::timer_timeout()
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{
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scrollPos = (scrollPos + 2) % wholeTextSize.width();
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update();
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}
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