WidgetScrollbarDecorator.cpp

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// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2018 ISIS Rutherford Appleton Laboratory UKRI,
//   NScD Oak Ridge National Laboratory, European Spallation Source,
//   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
// SPDX - License - Identifier: GPL - 3.0 +
//----------------------------------
// Includes
//----------------------------------
#include "MantidQtWidgets/Common/WidgetScrollbarDecorator.h"
 
#include <QMainWindow>
 
using namespace MantidQt::API;
 
//-----------------------------------------------------------------------------
WidgetScrollbarDecorator::WidgetScrollbarDecorator(QWidget *target) : m_target(target), m_enabled(false) {
  // Off-screen widget to hold layout/widgets when scrolling disabled
  m_offscreen = new QWidget(nullptr);
 
  // This layout replaces dialog's main layout when scrolling enabled
  m_layout = new QVBoxLayout(m_offscreen);
  m_layout->setSpacing(0);
  m_layout->setMargin(0);
 
  // QScrollArea provides scrolling functionality
  m_scrollarea = new QScrollArea(m_offscreen);
  m_scrollarea->setFrameStyle(QFrame::NoFrame);
  m_layout->addWidget(m_scrollarea);
 
  // Viewport represents the inside of QScrollArea
  // It will take over parentship of the layout and widgets of the target
  m_viewport = new QWidget(m_scrollarea);
  m_scrollarea->setWidget(m_viewport);
  m_scrollarea->setWidgetResizable(true);
 
  // With QMainWindows we must work on the centralWidget instead
  auto mainwindow = dynamic_cast<QMainWindow *>(m_target);
  if (mainwindow)
    m_target = mainwindow->centralWidget();
}
 
//-----------------------------------------------------------------------------
WidgetScrollbarDecorator::~WidgetScrollbarDecorator() {
  // Must be deleted manually since it has no parent
  delete m_offscreen;
}
 
//-----------------------------------------------------------------------------
bool WidgetScrollbarDecorator::enabled() const { return m_enabled; }
 
//-----------------------------------------------------------------------------
void WidgetScrollbarDecorator::setEnabled(bool enable) {
  // Only enable if scrollbars were previously disabled
  if (enable && !enabled()) {
    m_viewport->setLayout(m_target->layout());
    m_target->setLayout(m_layout);
  }
 
  // Only disable if scrollbars were previously enabled
  if (!enable && enabled()) {
    m_offscreen->setLayout(m_target->layout());
    m_target->setLayout(m_viewport->layout());
  }
 
  m_enabled = enable;
}
 
//-----------------------------------------------------------------------------
void WidgetScrollbarDecorator::setThresholdWidth(int width) { m_viewport->setMinimumWidth(width); }
 
//-----------------------------------------------------------------------------
void WidgetScrollbarDecorator::setThresholdHeight(int height) { m_viewport->setMinimumHeight(height); }
 
//-----------------------------------------------------------------------------
void WidgetScrollbarDecorator::setThresholdSize(int width, int height) { m_viewport->setMinimumSize(width, height); }