text: /****************************************************************************
  **
  ** Copyright (C) 2015 The Qt Company Ltd.
  ** Contact: http://www.qt.io/licensing/
  **
  ** This file is part of the Qt Designer of the Qt Toolkit.
  **
  ** $QT_BEGIN_LICENSE:LGPL21$
  ** Commercial License Usage
  ** Licensees holding valid commercial Qt licenses may use this file in
  ** accordance with the commercial license agreement provided with the
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  **
  ** GNU Lesser General Public License Usage
  ** Alternatively, this file may be used under the terms of the GNU Lesser
  ** General Public License version 2.1 or version 3 as published by the Free
  ** Software Foundation and appearing in the file LICENSE.LGPLv21 and
  ** LICENSE.LGPLv3 included in the packaging of this file. Please review the
  ** following information to ensure the GNU Lesser General Public License
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  **
  ** As a special exception, The Qt Company gives you certain additional
  ** rights. These rights are described in The Qt Company LGPL Exception
  ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
  **
  ** $QT_END_LICENSE$
  **
  ****************************************************************************/
  
  #include "spacer_widget_p.h"
  #include "layoutinfo_p.h"
  
  #include <QtDesigner/abstractformwindow.h>
  #include <QtDesigner/QDesignerFormWindowInterface>
  #include <QtDesigner/QDesignerFormEditorInterface>
  #include <QtDesigner/QDesignerPropertySheetExtension>
  #include <QtDesigner/QExtensionManager>
  
  #include <QtWidgets/QLayout>
  #include <QtGui/QPainter>
  #include <QtGui/qevent.h>
  #include <QtCore/qdebug.h>
  
  QT_BEGIN_NAMESPACE
  
  // The Spacer widget is Designer representation of  QLayoutItem.
  // It uses QLayoutItem's sizeHint property as QWidget
  // sizeHint and the QLayoutItem's sizeType property as QWidget size policy.
  // If it is not within a layout, it adds a margin (m_SizeOffset) around it
  // to avoid being shrunk to an invisible state when the sizeHint is reset to 0,0
  // and enables sizeHandle-resizing. In a layout, however, this m_SizeOffset
  // should not be applied for  pixel-exact design.
  
  Spacer::Spacer(QWidget *parent) :
      QWidget(parent),
      m_SizeOffset(3, 3), // A small offset to ensure the spacer is still visible when reset to size 0,0
      m_orientation(Qt::Vertical),
      m_interactive(true),
      m_layoutState(UnknownLayoutState),
      m_sizeHint(0, 0)
  {
      setAttribute(Qt::WA_MouseNoMask);
      m_formWindow = QDesignerFormWindowInterface::findFormWindow(this);
      setSizeType(QSizePolicy::Expanding);
  }
  
  bool Spacer::event(QEvent *e)
  {
      switch (e->type()) {
      case QEvent::ToolTip:
          updateToolTip(); // Tooltip includes size, so, refresh on demand
          break;
      case QEvent::ParentChange: // Cache information about 'being in layout' which is expensive to calculate.
          m_layoutState = UnknownLayoutState;
          break;
      default:
          break;
      }
      return QWidget::event(e);
  }
  
  bool Spacer::isInLayout() const
  {
      if (m_layoutState == UnknownLayoutState) {
          m_layoutState = OutsideLayout;
          if (m_formWindow)
              if (const QWidget *parent = parentWidget())
                  if (qdesigner_internal::LayoutInfo::managedLayoutType(m_formWindow->core(), parent) != qdesigner_internal::LayoutInfo::NoLayout)
                      m_layoutState = InLayout;
      }
      return m_layoutState == InLayout;
  }
  
  void Spacer::paintEvent(QPaintEvent *)
  {
      // Only draw spacers when we're editting widgets
      if (m_formWindow != 0 && m_formWindow->currentTool() != 0)
          return;
  
      QPainter p(this);
      p.setPen(Qt::blue);
      const int w = width();
      const int h = height();
      if (w * h == 0)
          return;
  
      if (w <= m_SizeOffset.width() || h <= m_SizeOffset.height()) {
          const int lw = w - 1;
          const int lh = h - 1;
          switch (m_orientation) {
          case Qt::Horizontal:
              p.drawLine(0,  0, 0,  lh);
              p.drawLine(lw, 0, lw, lh);
              break;
          case Qt::Vertical:
              p.drawLine(0, 0,  lw, 0);
              p.drawLine(0, lh, lw, lh);
              break;
          }
          return;
      }
      if (m_orientation == Qt::Horizontal) {
          const int dist = 3;
          const int amplitude = qMin(3, h / 3);
          const int base = h / 2;
          int i = 0;
          p.setPen(Qt::white);
          for (i = 0; i < w / 3 +2; ++i)
              p.drawLine(i * dist, base - amplitude, i * dist + dist / 2, base + amplitude);
          p.setPen(Qt::blue);
          for (i = 0; i < w / 3 +2; ++i)
              p.drawLine(i * dist + dist / 2, base + amplitude, i * dist + dist, base - amplitude);
          const int y = h/2;
          p.drawLine(0, y-10, 0, y+10);
          p.drawLine(w - 1, y-10, w - 1, y+10);
      } else {
          const int dist = 3;
          const int amplitude = qMin(3, w / 3);
          const int base = w / 2;
          int i = 0;
          p.setPen(Qt::white);
          for (i = 0; i < h / 3 +2; ++i)
              p.drawLine(base - amplitude, i * dist, base + amplitude,i * dist + dist / 2);
          p.setPen(Qt::blue);
          for (i = 0; i < h / 3 +2; ++i)
              p.drawLine(base + amplitude, i * dist + dist / 2, base - amplitude, i * dist + dist);
          const int x = w/2;
          p.drawLine(x-10, 0, x+10, 0);
          p.drawLine(x-10, h - 1, x+10, h - 1);
      }
  }
  
  void Spacer::resizeEvent(QResizeEvent* e)
  {
      QWidget::resizeEvent(e);
      // When resized by widget handle dragging after a reset (QSize(0, 0)):
      // Mark the property as changed (geometry and sizeHint are in sync except for 'changed').
      if (m_formWindow) {
          const QSize oldSize = e->oldSize();
          if (oldSize.isNull() || oldSize.width() <= m_SizeOffset.width() || oldSize.height() <= m_SizeOffset.height())
              if (QDesignerPropertySheetExtension *sheet = qt_extension<QDesignerPropertySheetExtension*>(m_formWindow->core()->extensionManager(), this))
                  sheet->setChanged(sheet->indexOf(QStringLiteral("sizeHint")), true);
      }
  
      updateMask();
  
      if (!m_interactive)
          return;
  
      if (!isInLayout()) { // Allow size-handle resize only if not in layout
          const QSize currentSize = size();
          if (currentSize.width() >= m_SizeOffset.width() && currentSize.height() >= m_SizeOffset.height())
              m_sizeHint = currentSize - m_SizeOffset;
      }
  }
  
  void Spacer::updateMask()
  {
      QRegion r(rect());
      const int w = width();
      const int h = height();
      if (w > 1 && h > 1) {
          if (m_orientation == Qt::Horizontal) {
              const int amplitude = qMin(3, h / 3);
              const int base = h / 2;
              r = r.subtracted(QRect(1, 0, w - 2, base - amplitude));
              r = r.subtracted(QRect(1, base + amplitude, w - 2, h - base - amplitude));
          } else {
              const int amplitude = qMin(3, w / 3);
              const int base = w / 2;
              r = r.subtracted(QRect(0, 1, base - amplitude, h - 2));
              r = r.subtracted(QRect(base + amplitude, 1, w - base - amplitude, h - 2));
          }
      }
      setMask(r);
  }
  
  void Spacer::setSizeType(QSizePolicy::Policy t)
  {
      const QSizePolicy sizeP = m_orientation == Qt::Vertical ? QSizePolicy(QSizePolicy::Minimum, t) : QSizePolicy(t, QSizePolicy::Minimum);
      setSizePolicy(sizeP);
  }
  
  
  QSizePolicy::Policy Spacer::sizeType() const
  {
      return m_orientation == Qt::Vertical ? sizePolicy().verticalPolicy() : sizePolicy().horizontalPolicy();
  }
  
  Qt::Alignment Spacer::alignment() const
  {
      // For grid layouts
      return m_orientation == Qt::Vertical ?  Qt::AlignHCenter : Qt::AlignVCenter;
  }
  
  QSize Spacer::sizeHint() const
  {
      return isInLayout() ? m_sizeHint : m_sizeHint + m_SizeOffset;
  }
  
  QSize Spacer::sizeHintProperty() const
  {
      return m_sizeHint;
  }
  
  void Spacer::setSizeHintProperty(const QSize &s)
  {
      m_sizeHint = s;
  
      if (!isInLayout()) // Visible resize only if not in layout
          resize(s + m_SizeOffset);
  
      updateGeometry();
  }
  
  Qt::Orientation Spacer::orientation() const
  {
      return m_orientation;
  }
  
  void Spacer::setOrientation(Qt::Orientation o)
  {
      if (m_orientation == o)
          return;
  
      const QSizePolicy::Policy st = sizeType(); // flip size type
      m_orientation = o;
      setSizeType(st);
  
      if (m_interactive) {
          m_sizeHint = QSize(m_sizeHint.height(), m_sizeHint.width());
          if (!isInLayout())
              resize(m_sizeHint + m_SizeOffset);
      }
  
      updateMask();
      update();
      updateGeometry();
  }
  
  void Spacer::updateToolTip()
  {
      const QString format = m_orientation == Qt::Horizontal ? tr("Horizontal Spacer '%1', %2 x %3") : tr("Vertical Spacer '%1', %2 x %3");
      QString msg = format.arg(objectName()).arg(m_sizeHint.width()).arg(m_sizeHint.height());
      setToolTip(msg);
  }
  
  QT_END_NAMESPACE
  