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