strawberry-audio-player-windows-mac-linux/src/widgets/widgetfadehelper.cpp

/*
 * Strawberry Music Player
 * This file was part of Clementine.
 * Copyright 2010, David Sansome <me@davidsansome.com>
 *
 * Strawberry is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Strawberry 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Strawberry.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <QObject>
#include <QWidget>
#include <QImage>
#include <QPixmap>
#include <QPainter>
#include <QTimeLine>
#include <QResizeEvent>
#include <QEvent>

#include "widgetfadehelper.h"
#include "core/qt_blurimage.h"

const int WidgetFadeHelper::kLoadingPadding = 9;
const int WidgetFadeHelper::kLoadingBorderRadius = 10;

WidgetFadeHelper::WidgetFadeHelper(QWidget *parent, const int msec)
    : QWidget(parent),
      parent_(parent),
      blur_timeline_(new QTimeLine(msec, this)),
      fade_timeline_(new QTimeLine(msec, this)) {

  parent->installEventFilter(this);

  connect(blur_timeline_, SIGNAL(valueChanged(qreal)), SLOT(update()));
  connect(fade_timeline_, SIGNAL(valueChanged(qreal)), SLOT(update()));
  connect(fade_timeline_, SIGNAL(finished()), SLOT(FadeFinished()));

  hide();

}

bool WidgetFadeHelper::eventFilter(QObject *obj, QEvent *event) {

  // We're only interested in our parent's resize events
  if (obj != parent_ || event->type() != QEvent::Resize) return false;

  // Don't care if we're hidden
  if (!isVisible()) return false;

  QResizeEvent *re = static_cast<QResizeEvent*>(event);
  if (re->oldSize() == re->size()) {
    // Ignore phoney resize events
    return false;
  }

  // Get a new capture of the parent
  hide();
  CaptureParent();
  show();
  return false;

}

void WidgetFadeHelper::StartBlur() {

  CaptureParent();

  // Cover the parent
  raise();
  show();

  // Start the timeline
  blur_timeline_->stop();
  blur_timeline_->start();

  setAttribute(Qt::WA_TransparentForMouseEvents, false);

}

void WidgetFadeHelper::CaptureParent() {

  // Take a "screenshot" of the window
  original_pixmap_ = parent_->grab();
  QImage original_image = original_pixmap_.toImage();

  // Blur it
  QImage blurred(original_image.size(), QImage::Format_ARGB32_Premultiplied);
  blurred.fill(Qt::transparent);

  QPainter blur_painter(&blurred);
  blur_painter.save();
  qt_blurImage(&blur_painter, original_image, 10.0, true, false);
  blur_painter.restore();

  // Draw some loading text over the top
  QFont loading_font(font());
  loading_font.setBold(true);
  QFontMetrics loading_font_metrics(loading_font);

  const QString loading_text = tr("Loading...");
#if (QT_VERSION >= QT_VERSION_CHECK(5, 11, 0))
  const QSize loading_size(kLoadingPadding * 2 + loading_font_metrics.horizontalAdvance(loading_text), kLoadingPadding * 2 + loading_font_metrics.height());
#else
  const QSize loading_size(kLoadingPadding * 2 + loading_font_metrics.width(loading_text), kLoadingPadding * 2 + loading_font_metrics.height());
#endif
  const QRect loading_rect((blurred.width() - loading_size.width()) / 2, 100, loading_size.width(), loading_size.height());

  blur_painter.setRenderHint(QPainter::Antialiasing);

  blur_painter.translate(0.5, 0.5);
  blur_painter.setPen(QColor(200, 200, 200, 255));
  blur_painter.setBrush(QColor(200, 200, 200, 192));
  blur_painter.drawRoundedRect(loading_rect, kLoadingBorderRadius, kLoadingBorderRadius);

  blur_painter.setPen(palette().brush(QPalette::Text).color());
  blur_painter.setFont(loading_font);
  blur_painter.drawText(loading_rect.translated(-1, -1), Qt::AlignCenter, loading_text);
  blur_painter.translate(-0.5, -0.5);

  blur_painter.end();

  blurred_pixmap_ = QPixmap::fromImage(blurred);

  resize(parent_->size());

}

void WidgetFadeHelper::StartFade() {

  if (blur_timeline_->state() == QTimeLine::Running) {
    // Blur timeline is still running, so we need render the current state
    // into a new pixmap.
    QPixmap pixmap(original_pixmap_);
    QPainter painter(&pixmap);
    painter.setOpacity(blur_timeline_->currentValue());
    painter.drawPixmap(0, 0, blurred_pixmap_);
    painter.end();
    blurred_pixmap_ = pixmap;
  }
  blur_timeline_->stop();
  original_pixmap_ = QPixmap();

  // Start the timeline
  fade_timeline_->stop();
  fade_timeline_->start();

  setAttribute(Qt::WA_TransparentForMouseEvents, true);

}

void WidgetFadeHelper::paintEvent(QPaintEvent*) {

  QPainter p(this);

  if (fade_timeline_->state() != QTimeLine::Running) {
    // We're fading in the blur
    p.drawPixmap(0, 0, original_pixmap_);
    p.setOpacity(blur_timeline_->currentValue());
  }
  else {
    // Fading out the blur into the new image
    p.setOpacity(1.0 - fade_timeline_->currentValue());
  }

  p.drawPixmap(0, 0, blurred_pixmap_);

}

void WidgetFadeHelper::FadeFinished() {

  hide();
  original_pixmap_ = QPixmap();
  blurred_pixmap_ = QPixmap();

}