matrixion/src/ui/LoadingIndicator.cpp

// SPDX-FileCopyrightText: 2021 Nheko Contributors
//
// SPDX-License-Identifier: GPL-3.0-or-later

#include "LoadingIndicator.h"

#include <QPaintEvent>
#include <QPainter>
#include <QTimer>

LoadingIndicator::LoadingIndicator(QWidget *parent)
  : QWidget(parent)
  , interval_(70)
  , angle_(0)
  , color_(Qt::black)
{
    setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
    setFocusPolicy(Qt::NoFocus);

    timer_ = new QTimer(this);
    connect(timer_, SIGNAL(timeout()), this, SLOT(onTimeout()));
}

void
LoadingIndicator::paintEvent(QPaintEvent *e)
{
    Q_UNUSED(e)

    if (!timer_->isActive())
        return;

    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);

    int width = qMin(this->width(), this->height());

    int outerRadius = (width - 4) * 0.5f;
    int innerRadius = outerRadius * 0.78f;

    int capsuleRadius = (outerRadius - innerRadius) / 2;

    for (int i = 0; i < 8; ++i) {
        QColor color = color_;

        color.setAlphaF(1.0f - (i / 8.0f));

        painter.setPen(Qt::NoPen);
        painter.setBrush(color);

        qreal radius = capsuleRadius * (1.0f - (i / 16.0f));

        painter.save();

        painter.translate(rect().center());
        painter.rotate(angle_ - i * 45.0f);

        QPointF center = QPointF(-capsuleRadius, -innerRadius);
        painter.drawEllipse(center, radius * 2, radius * 2);

        painter.restore();
    }
}

void
LoadingIndicator::start()
{
    timer_->start(interval_);
    show();
}

void
LoadingIndicator::stop()
{
    timer_->stop();
    hide();
}

void
LoadingIndicator::onTimeout()
{
    angle_ = (angle_ + 45) % 360;
    repaint();
}