/*=========================================================================

   Program: ParaView
   Module:    $RCSfile$

   Copyright (c) 2005,2006 Sandia Corporation, Kitware Inc.
   All rights reserved.

   ParaView is a free software; you can redistribute it and/or modify it
   under the terms of the ParaView license version 1.2.

   See License_v1.2.txt for the full ParaView license.
   A copy of this license can be obtained by contacting
   Kitware Inc.
   28 Corporate Drive
   Clifton Park, NY 12065
   USA

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

========================================================================*/
#include "pqTransferFunctionWidget.h"

#include "QVTKOpenGLNativeWidget.h"
#include "pqCoreUtilities.h"
#include "pqTimer.h"
#include "vtkAxis.h"
#include "vtkBoundingBox.h"
#include "vtkBrush.h"
#include "vtkChartXY.h"
#include "vtkColorTransferFunction.h"
#include "vtkColorTransferFunctionItem.h"
#include "vtkCompositeControlPointsItem.h"
#include "vtkCompositeTransferFunctionItem.h"
#include "vtkContext2D.h"
#include "vtkContextMouseEvent.h"
#include "vtkContextScene.h"
#include "vtkContextView.h"
#include "vtkEventQtSlotConnect.h"
#include "vtkGenericOpenGLRenderWindow.h"
#include "vtkImageData.h"
#include "vtkNew.h"
#include "vtkObjectFactory.h"
#include "vtkPVColorTransferControlPointsItem.h"
#include "vtkPiecewiseControlPointsItem.h"
#include "vtkPiecewiseFunction.h"
#include "vtkPiecewiseFunctionItem.h"
#include "vtkRangeHandlesItem.h"
#include "vtkSMCoreUtilities.h"
#include "vtkSmartPointer.h"
#include "vtkVector.h"
#include "vtkWeakPointer.h"

#include <QColorDialog>
#include <QMainWindow>
#include <QPointer>
#include <QStatusBar>
#include <QSurfaceFormat>
#include <QVBoxLayout>

#include <algorithm>
#include <cassert>

namespace
{

//-----------------------------------------------------------------------------
// vtkTransferFunctionChartXY extends vtkChartXY to support following
// customizations:
// 1. The axes should always show the bounds for the transfer function's XY
//    range. Thus, we need to change the axes range whenever the transfer
//    function range changes.
//
// 2. If the transfer function range is too small, disable interaction and
//    potentially rendering of the transfer function since it won't be correct.
//
class vtkTransferFunctionChartXY : public vtkChartXY
{
  vtkVector2d XRange;
  bool DataValid;
  bool NeedUpdate;

  bool IsDataRangeValid(const double r[2]) const
  {
    double mr[2] = { r[0], r[1] };
    // If vtkSMCoreUtilities::AdjustRange() decided to adjust a valid range, it means the numbers
    // are too close to each other.
    return r[1] < r[0] ? false : (vtkSMCoreUtilities::AdjustRange(mr) == false);
  }

public:
  static vtkTransferFunctionChartXY* New();
  vtkTypeMacro(vtkTransferFunctionChartXY, vtkChartXY);

  bool SetTFRange(const vtkVector2d& range)
  {
    if (range != this->XRange)
    {
      this->XRange = range;
      this->NeedUpdate = true;
      return true;
    }
    return false;
  }

  void Update() override
  {
    this->Superclass::Update();
    if (this->NeedUpdate)
    {
      this->DataValid = this->IsDataRangeValid(this->XRange.GetData());
      this->AdjustAxes();
      this->NeedUpdate = false;
    }
  }
  bool PaintChildren(vtkContext2D* painter) override
  {
    if (this->DataValid)
    {
      return this->Superclass::PaintChildren(painter);
    }
    painter->DrawString(5, 5, "Data range too small to render.");
    return true;
  }

  bool MouseEnterEvent(const vtkContextMouseEvent& mouse) override
  {
    return (this->DataValid ? this->Superclass::MouseEnterEvent(mouse) : false);
  }
  bool MouseMoveEvent(const vtkContextMouseEvent& mouse) override
  {
    return (this->DataValid ? this->Superclass::MouseMoveEvent(mouse) : false);
  }
  bool MouseLeaveEvent(const vtkContextMouseEvent& mouse) override
  {
    return (this->DataValid ? this->Superclass::MouseLeaveEvent(mouse) : false);
  }
  bool MouseButtonPressEvent(const vtkContextMouseEvent& mouse) override
  {
    return (this->DataValid ? this->Superclass::MouseButtonPressEvent(mouse) : false);
  }
  bool MouseButtonReleaseEvent(const vtkContextMouseEvent& mouse) override
  {
    return (this->DataValid ? this->Superclass::MouseButtonReleaseEvent(mouse) : false);
  }
  bool MouseWheelEvent(const vtkContextMouseEvent& mouse, int delta) override
  {
    return (this->DataValid ? this->Superclass::MouseWheelEvent(mouse, delta) : false);
  }
  bool KeyPressEvent(const vtkContextKeyEvent& key) override
  {
    return (this->DataValid ? this->Superclass::KeyPressEvent(key) : false);
  }

protected:
  vtkTransferFunctionChartXY()
  {
    this->XRange = vtkVector2d(0, 0);
    this->NeedUpdate = false;
    this->DataValid = false;
  }
  ~vtkTransferFunctionChartXY() override = default;

  void AdjustAxes()
  {
    this->GetAxis(vtkAxis::BOTTOM)->SetUnscaledRange(this->XRange[0], this->XRange[1]);
    this->GetAxis(vtkAxis::LEFT)->SetRange(0, 1);

    // for recalculation of transforms using current axes ranges.
    this->RecalculatePlotTransforms();
  }

private:
  vtkTransferFunctionChartXY(const vtkTransferFunctionChartXY&);
  void operator=(const vtkTransferFunctionChartXY&);
};
vtkStandardNewMacro(vtkTransferFunctionChartXY);

} // end of namespace

//-----------------------------------------------------------------------------

class pqTransferFunctionWidget::pqInternals
{
  vtkNew<vtkGenericOpenGLRenderWindow> Window;

public:
  QPointer<QVTKOpenGLNativeWidget> Widget;
  vtkNew<vtkTransferFunctionChartXY> ChartXY;
  vtkNew<vtkContextView> ContextView;
  vtkNew<vtkEventQtSlotConnect> VTKConnect;
  vtkNew<vtkBrush> CheckerBrush;

  pqTimer Timer;
  pqTimer RangeTimer;
  pqTimer EditColorPointTimer;

  vtkSmartPointer<vtkRangeHandlesItem> RangeHandlesItem;
  vtkSmartPointer<vtkScalarsToColorsItem> TransferFunctionItem;
  vtkSmartPointer<vtkControlPointsItem> ControlPointsItem;
  unsigned long CurrentPointEditEventId;

  vtkWeakPointer<vtkScalarsToColors> ScalarsToColors;
  vtkWeakPointer<vtkPiecewiseFunction> PiecewiseFunction;

  pqInternals(pqTransferFunctionWidget* editor)
    : Widget(new QVTKOpenGLNativeWidget(editor))
    , CurrentPointEditEventId(0)
  {
    this->Timer.setSingleShot(true);
    this->Timer.setInterval(0);

    this->RangeTimer.setSingleShot(true);
    this->RangeTimer.setInterval(0);

    // A delay is necessary otherwise the color dialog grabs focus
    // too quickly causing #20758.
    this->EditColorPointTimer.setSingleShot(true);
    this->EditColorPointTimer.setInterval(100);

    this->Window->SetMultiSamples(8);

    this->Widget->setEnableHiDPI(true);
    this->Widget->setObjectName("1QVTKWidget0");
    this->Widget->setRenderWindow(this->Window);
    this->ContextView->SetRenderWindow(this->Window);

    this->ChartXY->SetAutoSize(true);
    this->ChartXY->SetShowLegend(false);
    this->ChartXY->SetZoomWithMouseWheel(false);
    this->ContextView->GetScene()->AddItem(this->ChartXY);
    this->ContextView->SetInteractor(this->Widget->interactor());
    this->ContextView->GetRenderWindow()->SetLineSmoothing(true);

    this->ChartXY->SetActionToButton(vtkChart::PAN, -1);
    this->ChartXY->SetActionToButton(vtkChart::ZOOM, -1);
    this->ChartXY->SetActionToButton(vtkChart::SELECT, vtkContextMouseEvent::RIGHT_BUTTON);
    this->ChartXY->SetActionToButton(vtkChart::SELECT_POLYGON, -1);

    this->Widget->setParent(editor);
    QVBoxLayout* layout = new QVBoxLayout(editor);
    layout->setContentsMargins(0, 0, 0, 0);
    layout->addWidget(this->Widget);

    this->ChartXY->SetAutoAxes(false);
    this->ChartXY->SetHiddenAxisBorder(8);
    for (int cc = 0; cc < 4; cc++)
    {
      this->ChartXY->GetAxis(cc)->SetVisible(false);
      this->ChartXY->GetAxis(cc)->SetBehavior(vtkAxis::FIXED);
    }
  }
  ~pqInternals() { this->cleanup(); }

  void initializeCheckerBoardBrush()
  {
    vtkNew<vtkImageData> texture;
    const int numPtsX = 32;
    const int numPtsY = 32;
    const int ncomp = 3;
    texture->SetDimensions(numPtsX, numPtsY, 1);
    texture->AllocateScalars(VTK_UNSIGNED_CHAR, ncomp);
    // assumes origin at lower left corner in a 32x32 square.
    // create a checkerboard with 4 sub-squares. texture property repeat
    // ensures this pattern is repeated.
    for (int i = 0; i < numPtsY; ++i)
    {
      for (int j = 0; j < numPtsX; ++j)
      {
        double val = 0;
        // lower left
        if (i < numPtsY / 2 && j < numPtsX / 2)
        {
          val = 225; // grey
        }
        // upper right
        else if (i >= numPtsY / 2 && j >= numPtsX / 2)
        {
          val = 225; // grey
        }
        // lower right
        else if (j >= numPtsX / 2)
        {
          val = 255; // white
        }
        // upper left
        else if (i >= numPtsY / 2)
        {
          val = 255; // white
        }
        for (int comp = 0; comp < ncomp; ++comp)
        {
          texture->SetScalarComponentFromDouble(i, j, 0, comp, val);
        }
      }
    }
    this->CheckerBrush->SetTexture(texture);
    this->CheckerBrush->SetTextureProperties(
      vtkBrush::TextureProperty::Repeat | vtkBrush::TextureProperty::Nearest);
  }

  void setUseCheckerBoardBrush(bool use)
  {
    this->ChartXY->SetBackgroundBrush(use ? this->CheckerBrush.GetPointer() : nullptr);
  }

  void cleanup()
  {
    this->RangeTimer.disconnect();
    this->VTKConnect->Disconnect();
    this->ChartXY->ClearPlots();
    if (this->ControlPointsItem && this->CurrentPointEditEventId)
    {
      this->ControlPointsItem->RemoveObserver(this->CurrentPointEditEventId);
      this->CurrentPointEditEventId = 0;
    }
    this->TransferFunctionItem = nullptr;
    this->RangeHandlesItem = nullptr;
    this->ControlPointsItem = nullptr;
  }
};

//-----------------------------------------------------------------------------
pqTransferFunctionWidget::pqTransferFunctionWidget(QWidget* parentObject)
  : Superclass(parentObject)
  , Internals(new pqInternals(this))
{
  // whenever the rendering timer times out, we render the widget.
  QObject::connect(&this->Internals->Timer, &QTimer::timeout, [this]() {
    auto renWin = this->Internals->ContextView->GetRenderWindow();
    if (this->isVisible())
    {
      renWin->Render();
    }
  });

  this->Internals->initializeCheckerBoardBrush();
  this->Internals->setUseCheckerBoardBrush(true);
  this->connect(&this->Internals->EditColorPointTimer, SIGNAL(timeout()),
    SLOT(editColorAtCurrentControlPoint()));
}

//-----------------------------------------------------------------------------
pqTransferFunctionWidget::~pqTransferFunctionWidget()
{
  delete this->Internals;
  this->Internals = nullptr;
}

//-----------------------------------------------------------------------------
vtkScalarsToColors* pqTransferFunctionWidget::scalarsToColors() const
{
  return this->Internals->ScalarsToColors;
}

//-----------------------------------------------------------------------------
vtkPiecewiseFunction* pqTransferFunctionWidget::piecewiseFunction() const
{
  return this->Internals->PiecewiseFunction;
}

//-----------------------------------------------------------------------------
void pqTransferFunctionWidget::initialize(
  vtkScalarsToColors* stc, bool stc_editable, vtkPiecewiseFunction* pwf, bool pwf_editable)
{
  this->Internals->cleanup();
  this->Internals->ScalarsToColors = stc;
  this->Internals->PiecewiseFunction = pwf;

  // TODO: If needed, we can support vtkLookupTable.
  vtkColorTransferFunction* ctf = vtkColorTransferFunction::SafeDownCast(stc);

  if (ctf != nullptr && pwf == nullptr)
  {
    vtkNew<vtkColorTransferFunctionItem> item;
    item->SetColorTransferFunction(ctf);
    this->Internals->TransferFunctionItem = item;

    vtkNew<vtkRangeHandlesItem> handlesItem;
    handlesItem->SetColorTransferFunction(ctf);
    handlesItem->SetHandleWidth(4.0);
    this->Internals->RangeHandlesItem = handlesItem;

    if (stc_editable)
    {
      vtkNew<vtkPVColorTransferControlPointsItem> cpItem;
      cpItem->SetColorTransferFunction(ctf);
      cpItem->SetColorFill(true);
      cpItem->SetEndPointsXMovable(false);
      cpItem->SetEndPointsYMovable(false);
      cpItem->SetLabelFormat("%.3f");
      this->Internals->ControlPointsItem = cpItem;

      this->Internals->CurrentPointEditEventId =
        cpItem->AddObserver(vtkControlPointsItem::CurrentPointEditEvent, this,
          &pqTransferFunctionWidget::onCurrentPointEditEvent);
    }
  }
  else if (ctf == nullptr && pwf != nullptr)
  {
    vtkNew<vtkPiecewiseFunctionItem> item;
    item->SetPiecewiseFunction(pwf);

    this->Internals->TransferFunctionItem = item;

    if (pwf_editable)
    {
      vtkNew<vtkPiecewiseControlPointsItem> cpItem;
      cpItem->SetPiecewiseFunction(pwf);
      cpItem->SetEndPointsXMovable(false);
      cpItem->SetEndPointsYMovable(true);
      cpItem->SetLabelFormat("%.3f: %.3f");
      this->Internals->ControlPointsItem = cpItem;
    }
  }
  else if (ctf != nullptr && pwf != nullptr)
  {
    vtkNew<vtkCompositeTransferFunctionItem> item;
    item->SetOpacityFunction(pwf);
    item->SetColorTransferFunction(ctf);
    item->SetMaskAboveCurve(true);
    this->Internals->TransferFunctionItem = item;

    vtkNew<vtkRangeHandlesItem> handlesItem;
    handlesItem->SetColorTransferFunction(ctf);
    this->Internals->RangeHandlesItem = handlesItem;

    if (pwf_editable && stc_editable)
    {
      // NOTE: this hasn't been tested yet.
      vtkNew<vtkCompositeControlPointsItem> cpItem;
      cpItem->SetPointsFunction(vtkCompositeControlPointsItem::ColorAndOpacityPointsFunction);
      cpItem->SetOpacityFunction(pwf);
      cpItem->SetColorTransferFunction(ctf);
      cpItem->SetEndPointsXMovable(false);
      cpItem->SetEndPointsYMovable(true);
      cpItem->SetUseOpacityPointHandles(true);
      cpItem->SetLabelFormat("%.3f: %.3f");
      this->Internals->ControlPointsItem = cpItem;
    }
    else if (pwf_editable)
    {
      vtkNew<vtkCompositeControlPointsItem> cpItem;
      cpItem->SetPointsFunction(vtkCompositeControlPointsItem::OpacityPointsFunction);
      cpItem->SetOpacityFunction(pwf);
      cpItem->SetColorTransferFunction(ctf);
      cpItem->SetEndPointsXMovable(false);
      cpItem->SetEndPointsYMovable(true);
      cpItem->SetUseOpacityPointHandles(true);
      cpItem->SetLabelFormat("%.3f: %.3f");
      this->Internals->ControlPointsItem = cpItem;
    }
  }
  else
  {
    return;
  }

  this->Internals->ChartXY->AddPlot(this->Internals->TransferFunctionItem);

  if (this->Internals->ControlPointsItem)
  {
    this->Internals->ControlPointsItem->UseAddPointItemOn();
    this->Internals->ChartXY->AddPlot(this->Internals->ControlPointsItem->GetAddPointItem());
  }

  if (this->Internals->RangeHandlesItem)
  {
    pqCoreUtilities::connect(this->Internals->RangeHandlesItem, vtkCommand::EndInteractionEvent,
      this, SLOT(onRangeHandlesRangeChanged()));
    pqCoreUtilities::connect(this->Internals->RangeHandlesItem,
      vtkCommand::LeftButtonDoubleClickEvent, this, SIGNAL(rangeHandlesDoubleClicked()));
    pqCoreUtilities::connect(
      this->Internals->RangeHandlesItem, vtkCommand::HighlightEvent, this, SLOT(showUsageStatus()));
    this->Internals->ChartXY->AddPlot(this->Internals->RangeHandlesItem);
  }

  if (this->Internals->ControlPointsItem)
  {
    this->Internals->ControlPointsItem->SetEndPointsRemovable(false);
    this->Internals->ControlPointsItem->SetShowLabels(true);
    this->Internals->ChartXY->AddPlot(this->Internals->ControlPointsItem);

    pqCoreUtilities::connect(this->Internals->ControlPointsItem,
      vtkControlPointsItem::CurrentPointChangedEvent, this, SLOT(onCurrentChangedEvent()));
    pqCoreUtilities::connect(this->Internals->ControlPointsItem, vtkCommand::EndEvent, this,
      SIGNAL(controlPointsModified()));
  }

  // If the transfer functions change, we need to re-render the view. This ensures that.
  // In some cases, the delta can be called for the pwf and the ctf, but it is not a problem.
  if (pwf)
  {
    this->Internals->VTKConnect->Connect(
      pwf, vtkCommand::ModifiedEvent, &this->Internals->RangeTimer, SLOT(start()));

    // whenever the range timer times out, we try to change the range
    QObject::connect(&this->Internals->RangeTimer, &QTimer::timeout, [pwf, this]() {
      if (this->Internals->ChartXY->SetTFRange(vtkVector2d(pwf->GetRange())))
      {
        // The range have actually been changed, rerender and Q_EMIT the signal
        this->render();
        Q_EMIT this->chartRangeModified();
      }
    });
    this->Internals->ChartXY->SetTFRange(vtkVector2d(pwf->GetRange()));
  }
  if (ctf)
  {
    this->Internals->VTKConnect->Connect(
      ctf, vtkCommand::ModifiedEvent, &this->Internals->RangeTimer, SLOT(start()));

    // whenever the range timer times out, we try to change the range
    QObject::connect(&this->Internals->RangeTimer, &QTimer::timeout, [ctf, this]() {
      if (this->Internals->ChartXY->SetTFRange(vtkVector2d(ctf->GetRange())))
      {
        // The range has actually been changed, rerender and Q_EMIT the signal
        this->render();
        Q_EMIT this->chartRangeModified();
      }
    });
    this->Internals->ChartXY->SetTFRange(vtkVector2d(ctf->GetRange()));
  }

  pqCoreUtilities::connect(this->Internals->Widget->interactor(), vtkCommand::MouseMoveEvent, this,
    SLOT(showUsageStatus()));
}

//-----------------------------------------------------------------------------
void pqTransferFunctionWidget::onCurrentPointEditEvent()
{
  // defer the invocation to avoid paraview/paraview#20758.
  auto& internals = (*this->Internals);
  internals.EditColorPointTimer.start();
}

//-----------------------------------------------------------------------------
void pqTransferFunctionWidget::editColorAtCurrentControlPoint()
{
  vtkColorTransferControlPointsItem* cpitem =
    vtkColorTransferControlPointsItem::SafeDownCast(this->Internals->ControlPointsItem);
  if (cpitem == nullptr)
  {
    return;
  }

  vtkIdType currentIdx = cpitem->GetCurrentPoint();
  if (currentIdx < 0)
  {
    return;
  }

  vtkColorTransferFunction* ctf = cpitem->GetColorTransferFunction();
  assert(ctf != nullptr);

  // Disable the interactor to ignore any events that may be issues
  // from the operating system after the dialog is shown and closed.
  // Fixes #20758.
  this->Internals->Widget->interactor()->Disable();

  double xrgbms[6];
  ctf->GetNodeValue(currentIdx, xrgbms);
  QColor color = QColorDialog::getColor(QColor::fromRgbF(xrgbms[1], xrgbms[2], xrgbms[3]), this,
    "Select Color", QColorDialog::DontUseNativeDialog);
  if (color.isValid())
  {
    xrgbms[1] = color.redF();
    xrgbms[2] = color.greenF();
    xrgbms[3] = color.blueF();
    ctf->SetNodeValue(currentIdx, xrgbms);

    Q_EMIT this->controlPointsModified();
  }

  // Simulate a MouseButtonReleaseEvent that can get lost when the color
  // selector is closed. Fixes #20758.
  vtkContextMouseEvent mouseEvent;
  mouseEvent.SetButton(vtkContextMouseEvent::LEFT_BUTTON);
  cpitem->MouseButtonReleaseEvent(mouseEvent);

  // Re-enable the widget interactor a short time after the dialog closes.
  // Fixes #20758.
  QTimer::singleShot(100, [=]() { this->Internals->Widget->interactor()->Enable(); });
}

//-----------------------------------------------------------------------------
void pqTransferFunctionWidget::onCurrentChangedEvent()
{
  if (this->Internals->ControlPointsItem)
  {
    Q_EMIT this->currentPointChanged(this->Internals->ControlPointsItem->GetCurrentPoint());
  }
}

//-----------------------------------------------------------------------------
vtkIdType pqTransferFunctionWidget::currentPoint() const
{
  if (this->Internals->ControlPointsItem)
  {
    return this->Internals->ControlPointsItem->GetCurrentPoint();
  }

  return -1;
}

//-----------------------------------------------------------------------------
void pqTransferFunctionWidget::setCurrentPoint(vtkIdType index)
{
  if (this->Internals->ControlPointsItem)
  {
    if (index < -1 || index >= this->Internals->ControlPointsItem->GetNumberOfPoints())
    {
      index = -1;
    }
    this->Internals->ControlPointsItem->SetCurrentPoint(index);
  }
}

//-----------------------------------------------------------------------------
vtkIdType pqTransferFunctionWidget::numberOfControlPoints() const
{
  return this->Internals->ControlPointsItem
    ? this->Internals->ControlPointsItem->GetNumberOfPoints()
    : 0;
}

//-----------------------------------------------------------------------------
void pqTransferFunctionWidget::SetControlPointsFreehandDrawing(bool use)
{
  this->Internals->ControlPointsItem->SetDrawPoints(!use);
  this->Internals->ControlPointsItem->SetStrokeMode(use);
  this->render();
}

//-----------------------------------------------------------------------------
bool pqTransferFunctionWidget::GetControlPointsFreehandDrawing() const
{
  return this->Internals->ControlPointsItem->GetStrokeMode();
}

//-----------------------------------------------------------------------------
void pqTransferFunctionWidget::SetLogScaleXAxis(bool logScale)
{
  this->Internals->ChartXY->GetAxis(vtkAxis::BOTTOM)->SetLogScale(logScale);
}

//-----------------------------------------------------------------------------
bool pqTransferFunctionWidget::GetLogScaleXAxis() const
{
  return this->Internals->ChartXY->GetAxis(vtkAxis::BOTTOM)->GetLogScale();
}

//-----------------------------------------------------------------------------
void pqTransferFunctionWidget::render()
{
  this->Internals->Timer.start();
}

//-----------------------------------------------------------------------------
void pqTransferFunctionWidget::setCurrentPointPosition(double xpos)
{
  vtkIdType currentPid = this->currentPoint();
  if (currentPid < 0)
  {
    return;
  }

  vtkIdType numPts = this->Internals->ControlPointsItem->GetNumberOfPoints();
  if (currentPid >= 0)
  {
    double start_point[4];
    this->Internals->ControlPointsItem->GetControlPoint(0, start_point);
    xpos = std::max(start_point[0], xpos);
  }
  if (currentPid <= (numPts - 1))
  {
    double end_point[4];
    this->Internals->ControlPointsItem->GetControlPoint(numPts - 1, end_point);
    xpos = std::min(end_point[0], xpos);
  }

  double point[4];
  this->Internals->ControlPointsItem->GetControlPoint(currentPid, point);
  if (point[0] != xpos)
  {
    point[0] = xpos;
    this->Internals->ControlPointsItem->SetControlPoint(currentPid, point);
  }
}

//-----------------------------------------------------------------------------
void pqTransferFunctionWidget::setHistogramTable(vtkTable* table)
{
  this->Internals->TransferFunctionItem->SetHistogramTable(table);
  this->render();
}

//-----------------------------------------------------------------------------
void pqTransferFunctionWidget::onRangeHandlesRangeChanged()
{
  if (this->Internals->RangeHandlesItem)
  {
    double range[2];
    this->Internals->RangeHandlesItem->GetHandlesRange(range);
    Q_EMIT this->rangeHandlesRangeChanged(range[0], range[1]);
  }
}

//-----------------------------------------------------------------------------
void pqTransferFunctionWidget::showUsageStatus()
{
  QMainWindow* mainWindow = qobject_cast<QMainWindow*>(pqCoreUtilities::mainWidget());
  if (mainWindow)
  {
    mainWindow->statusBar()->showMessage(
      tr("Drag a handle to change the range. "
         "Double click it to set custom range. Return/Enter to edit color."),
      2000);
  }
}
