ViewportBuffer.cpp

 
/* SPDX-License-Identifier: CC0-1.0 */
 
#include "IsisDebug.h"
 
#include "ViewportBuffer.h"
#include "ViewportBufferAction.h"
#include "ViewportBufferStretch.h"
#include "ViewportBufferFill.h"
#include "ViewportBufferTransform.h"
 
#include <QApplication>
#include <QQueue>
#include <QRect>
#include <QScrollBar>
 
#include "Brick.h"
#include "CubeDataThread.h"
#include "CubeViewport.h"
#include "SpecialPixel.h"
#include "PixelType.h"
 
 
#define round(x) ((x) > 0.0 ? (x) + 0.5 : (x) - 0.5)
 
 
using namespace std;
 
 
namespace Isis {
  ViewportBuffer::ViewportBuffer(CubeViewport *viewport,
                                 CubeDataThread *cubeData,
                                 int cubeId) {
    p_dataThread = cubeData;
    p_cubeId = cubeId;
 
    p_actions = 0;
 
    p_actions = new QQueue< ViewportBufferAction * >();
    p_viewport = viewport;
    p_bufferInitialized = false;
    p_band = -1;
    p_enabled = true;
    p_initialStretchDone = false;
    p_viewportHeight = p_viewport->viewport()->height();
    p_oldViewportHeight = p_viewport->viewport()->height();
    p_vertScrollBarPos = p_viewport->verticalScrollBar()->value();
    p_oldVertScrollBarPos = p_viewport->verticalScrollBar()->value();
 
    p_requestedFillArea = 0.0;
    p_bricksOrdered = true;
 
    connect(this, SIGNAL(ReadCube(int, int, int, int, int, int, void *)),
            p_dataThread, SLOT(ReadCube(int, int, int, int, int, int, void *)));
 
    connect(p_dataThread, SIGNAL(ReadReady(void *, int, const Isis::Brick *)),
            this, SLOT(DataReady(void *, int, const Isis::Brick *)));
 
    connect(this, SIGNAL(DoneWithData(int, const Isis::Brick *)),
            p_dataThread, SLOT(DoneWithData(int, const Isis::Brick *)));
  }
 
  ViewportBuffer::~ViewportBuffer() {
    disconnect(this, SIGNAL(ReadCube(int, int, int, int, int, int, void *)),
               p_dataThread, SLOT(ReadCube(int, int, int, int, int, int, void *)));
 
    disconnect(p_dataThread, SIGNAL(ReadReady(void *, int, const Isis::Brick *)),
               this, SLOT(DataReady(void *, int, const Isis::Brick *)));
 
    disconnect(this, SIGNAL(DoneWithData(int, const Isis::Brick *)),
               p_dataThread, SLOT(DoneWithData(int, const Isis::Brick *)));
 
    p_dataThread = NULL;
 
    if(p_actions) {
      while(!p_actions->empty()) {
        ViewportBufferAction *action = p_actions->dequeue();
        if(action) {
          delete action;
          action = NULL;
        }
      }
      delete p_actions;
      p_actions = NULL;
    }
 
    emptyBuffer(true);
  }
 
 
  void ViewportBuffer::fillBuffer(QRect rect) {
    if(p_band == -1) {
      throw IException(IException::Programmer, "invalid band", _FILEINFO_);
    }
 
    ViewportBufferFill *newFill = createViewportBufferFill(
                                    rect.intersected(bufferXYRect()), false);
    enqueueAction(newFill);
    doQueuedActions();
  }
 
 
  void ViewportBuffer::fillBuffer(QRect rect, const Brick *data) {
    if(p_band == -1) {
      throw IException(IException::Programmer, "invalid band", _FILEINFO_);
    }
 
    rect = rect.intersected(bufferXYRect());
 
    if (!rect.isValid())
      return;
 
    try {
      ViewportBufferFill *fill = createViewportBufferFill(rect, false);
 
      while(fill->shouldRequestMore()) {
        fill->incRequestPosition();
        fill->incReadPosition();
 
        for(int x = rect.left(); x <= rect.right(); x ++) {
          // Index into internal buffer is minus leftmost/topmost pixel
          int xIndex = x - fill->getLeftmostPixelPosition();
          int yIndex = fill->getRequestPosition() -
          fill->getTopmostPixelPosition();
 
          double samp = fill->viewportToSample(x);
          double line = fill->viewportToLine(fill->getRequestPosition());
          if (samp < data->Sample())
            samp = data->Sample();
          if (samp > data->Sample() + data->SampleDimension())
            samp = data->Sample() + data->SampleDimension();
          if (line < data->Line())
            line = data->Line();
          if (line > data->Line() + data->LineDimension())
            line = data->Line() + data->LineDimension();
 
          // Index into buffer is current sample - start sample
            //   *Brick indices are in units of cube pixels, not screen pixels
            int brickIndex = data->Index((int)(samp + 0.5), (int)(line + 0.5),
                                         p_band);
 
            if(brickIndex < 0) {
              p_buffer.at(yIndex).at(xIndex) = data->at(0);
            }
            else if(brickIndex >= data->size()) {
              p_buffer.at(yIndex).at(xIndex) = data->at(data->size() - 1);
            }
            else {
              if(yIndex < 0 || xIndex < 0 || yIndex >= (int) p_buffer.size() ||
                xIndex >= (int) p_buffer.at(yIndex).size()) {
                throw IException(IException::Programmer,
                                 "index out of range",
                                 _FILEINFO_);
                }
                else {
                  p_buffer.at(yIndex).at(xIndex) = data->at(brickIndex);
                }
            }
        }
      }
    }
    catch (IException &e) {
      throw IException(e, IException::Programmer, "Failed to load brick "
                       "into buffer", _FILEINFO_);
    }
  }
 
 
  void ViewportBuffer::DataReady(void *requester, int cubeId,
                                 const Brick *brick) {
    if(this != requester)
      return;
 
    if(p_actions->empty()) {
      throw IException(IException::Programmer, "no actions", _FILEINFO_);
    }
 
    ViewportBufferAction *curAction = p_actions->head();
 
    if(curAction->getActionType() != ViewportBufferAction::fill ||
        !curAction->started()) {
      throw IException(IException::Programmer, "not a fill action", _FILEINFO_);
    }
 
    ViewportBufferFill *fill = (ViewportBufferFill *) curAction;
 
    const QRect *rect = fill->getRect();
 
    int y = fill->getReadPosition(); // screen line
 
    // check to see if the next screen line's brick differs from this screen
    // line's brick.  If it does, which brick do we use?
    int curBrickLine = (int) (fill->viewportToLine(y) + 0.5);
    int nextBrickLine = (int) (fill->viewportToLine(y + 1) + 0.5);
    bool brickOrderCorrection = p_bricksOrdered;
    if (curBrickLine != nextBrickLine &&
        nextBrickLine == (int) (brick->Line() + 0.5)) {
      y++;
      p_bricksOrdered = false;
    }
    else {
      p_bricksOrdered = true;
    }
 
    double samp;
 
    // Loop through x values of rect on screen that we want to fill
    for(int x = rect->left(); x <= rect->right(); x++) {
      // Index into internal buffer is minus leftmost/topmost pixel
      int xIndex = x - fill->getLeftmostPixelPosition();
      int yIndex = y - fill->getTopmostPixelPosition();
 
      samp = fill->viewportToSample(x);
 
      // Index into buffer is current sample - start sample
      //   *Brick indices are in units of cube pixels, not screen pixels
      int brickIndex = (int)(samp + 0.5) - brick->Sample();
 
      if(brickIndex < 0) {
        p_buffer.at(yIndex).at(xIndex) = brick->at(0);
      }
      else if(brickIndex  >= brick->size()) {
        p_buffer.at(yIndex).at(xIndex) = brick->at(brick->size() - 1);
      }
      else {
        if(yIndex < 0 || xIndex < 0 || yIndex >= (int) p_buffer.size() ||
            xIndex >= (int) p_buffer.at(yIndex).size()) {
          IString msg = "An index out of range error was detected. ";
 
          if(yIndex < 0)
            msg += "The Y-Index [" + IString(yIndex) + "] is less than 0";
          else if(xIndex < 0)
            msg += "The X-Index [" + IString(xIndex) + "] is less than 0";
          else if(yIndex > (int)p_buffer.size())
            msg += "The Y-Index [" + IString(yIndex) + "] is greater than the "
                "Y-Size of [" + IString((int)p_buffer.size()) + "]";
          else if(xIndex > (int)p_buffer.at(yIndex).size())
            msg += "The X-Index [" + IString(xIndex) + " is greater than the "
                "X-Size of [" + IString((int) p_buffer.at(yIndex).size()) + "]";
 
          throw IException(IException::Programmer, msg, _FILEINFO_);
        }
        else {
          p_buffer.at(yIndex).at(xIndex) = brick->at(brickIndex);
        }
      }
    }
    fill->incReadPosition();
 
 
    if(fill->shouldRequestMore()) {
      if (p_bricksOrdered) {
        requestCubeLine(fill);
      }
      else {
        if (brickOrderCorrection) {
          requestCubeLine(fill);
          requestCubeLine(fill);
        }
      }
    }
    else if(fill->doneReading()) {
      delete fill;
      fill = NULL;
      p_actions->dequeue();
      doQueuedActions();
    }
 
    emit DoneWithData(cubeId, brick);
  }
 
 
  void ViewportBuffer::enqueueAction(ViewportBufferAction *action) {
    if(action->getActionType() == ViewportBufferAction::fill) {
      QRect *fillRect = ((ViewportBufferFill *)action)->getRect();
      p_requestedFillArea += fillRect->width() * fillRect->height();
    }
 
    if(p_actions->empty()) {
      p_viewport->enableProgress();
    }
 
    p_actions->enqueue(action);
  }
 
 
  const vector<double> &ViewportBuffer::getLine(int line) {
    if(!p_bufferInitialized || !p_enabled) {
      throw IException(IException::Programmer, "no data", _FILEINFO_);
    }
 
    if(line < 0 || line >= (int)p_buffer.size()) {
      throw IException(IException::Programmer,
                       "Invalid call to getLine",
                       _FILEINFO_);
    }
 
    return p_buffer.at(line);
  }
 
 
  QRect ViewportBuffer::getXYBoundingRect() {
    int startx, starty, endx, endy;
    p_viewport->cubeToViewport(0.5, 0.5, startx, starty);
 
    // Handle case where x,y 0,0 is sample,line 0,0 (which is outside the cube)
    //   and cubeToViewport still tells us 0.5, 0.5 is at x,y 0,0.
    double startSamp, startLine;
    p_viewport->viewportToCube(startx, starty, startSamp, startLine);
 
    if(startSamp < 0.5)
      startx ++;
 
    if(startLine < 0.5)
      starty ++;
 
    double rightmost = p_viewport->cubeSamples() + 0.5;
    double bottommost = p_viewport->cubeLines() + 0.5;
 
    p_viewport->cubeToViewport(rightmost, bottommost, endx, endy);
 
    if(endx < 0 || endy < 0)
      return QRect();
 
    double endSamp = -1, endLine = -1;
    p_viewport->viewportToCube(endx, endy, endSamp, endLine);
 
    if(endSamp > rightmost)
      endx --;
 
    if(endLine > bottommost)
      endy --;
 
    // Make sure our rect makes sense
    if(startx < 0) {
      startx = 0;
    }
 
    if(starty < 0) {
      starty = 0;
    }
 
    if(endx >= p_viewport->viewport()->width()) {
      endx = p_viewport->viewport()->width() - 1;
    }
 
    if(endy >= p_viewport->viewport()->height()) {
      endy = p_viewport->viewport()->height() - 1;
    }
 
    return QRect(startx, starty, endx - startx + 1, endy - starty + 1);
  }
 
 
  bool ViewportBuffer::hasEntireCube() {
    double sampTolerance = 0.05 * p_viewport->cubeSamples();
    double lineTolerance = 0.05 * p_viewport->cubeLines();
 
    bool hasCube = true;
 
    hasCube &= !working();
    hasCube &= p_sampLineBoundingRect[rectLeft] <= (1 + sampTolerance);
    hasCube &= p_sampLineBoundingRect[rectTop] <= (1 + lineTolerance);
    hasCube &= p_sampLineBoundingRect[rectRight] >= (p_viewport->cubeSamples() -
               sampTolerance);
    hasCube &= p_sampLineBoundingRect[rectBottom] >= (p_viewport->cubeLines() -
               lineTolerance);
    return hasCube;
  }
 
 
  QList<double> ViewportBuffer::getSampLineBoundingRect() {
    QRect xyRect = getXYBoundingRect();
    double ssamp, esamp, sline, eline;
    p_viewport->viewportToCube(xyRect.left(), xyRect.top(), ssamp, sline);
    p_viewport->viewportToCube(xyRect.right(), xyRect.bottom(), esamp, eline);
 
    QList<double> boundingRect;
 
    boundingRect.insert(rectLeft, ssamp);
    boundingRect.insert(rectTop, sline);
    boundingRect.insert(rectRight, esamp);
    boundingRect.insert(rectBottom, eline);
 
    return boundingRect;
  }
 
 
  void ViewportBuffer::updateBoundingRects() {
    p_oldXYBoundingRect = p_XYBoundingRect;
    p_XYBoundingRect = getXYBoundingRect();
 
    p_oldSampLineBoundingRect = p_sampLineBoundingRect;
    p_sampLineBoundingRect = getSampLineBoundingRect();
 
    p_oldViewportHeight = p_viewportHeight;
    p_viewportHeight = p_viewport->viewport()->height();
 
    p_oldVertScrollBarPos = p_vertScrollBarPos;
    // Add +1 to remove the black line at the top
    p_vertScrollBarPos = p_viewport->verticalScrollBar()->value() + 1;
  }
 
 
  ViewportBufferFill *ViewportBuffer::createViewportBufferFill(
    QRect someRect, bool useOldY) {
    QScrollBar *hsb = p_viewport->horizontalScrollBar();
    int xConstCoef = hsb->value();
    xConstCoef -= p_viewport->viewport()->width() / 2;
 
    // If panning over a full screen, it will try to create a fill rect that
    //   isn't actually valid. So, in the case of any bad fill rects we will
    //   fill everything.
    if(!someRect.isValid()) {
      throw IException(IException::Programmer, "Fill rect invalid", _FILEINFO_);
    }
 
    double xScale = p_viewport->scale();
 
    int yConstCoef = 0;
 
    if(!useOldY)
      yConstCoef = (p_vertScrollBarPos) - p_viewportHeight / 2 - 1;
    else
      yConstCoef = (p_oldVertScrollBarPos) - p_oldViewportHeight / 2 - 1;
 
    double yScale = xScale;
 
    QPoint topLeft;
 
    if(!useOldY) {
      topLeft = p_XYBoundingRect.topLeft();
    }
    else {
      topLeft = QPoint(p_XYBoundingRect.left(), p_oldXYBoundingRect.top());
    }
 
    ViewportBufferFill *newFill = new ViewportBufferFill(someRect, xConstCoef,
        xScale, yConstCoef, yScale, topLeft);
 
    return newFill;
  }
 
 
  void ViewportBuffer::requestCubeLine(ViewportBufferFill *fill) {
    if(p_band == -1) {
      throw IException(IException::Programmer, "invalid band", _FILEINFO_);
    }
 
    // Prep to create minimal buffer(s) to read the cube
    QRect &rect = *fill->getRect();
 
    double ssamp = fill->viewportToSample(rect.left());
 
    double esamp = fill->viewportToSample(rect.right());
 
    int brickWidth = (int)(ceil(esamp) - floor(ssamp)) + 1;
 
    if(brickWidth <= 0)
      return;
 
    double line = fill->viewportToLine(fill->getRequestPosition());
    int roundedSamp = (int)(ssamp + 0.5);
    int roundedLine = (int)(line + 0.5);
 
    emit ReadCube(p_cubeId, roundedSamp, roundedLine, roundedSamp + brickWidth,
                  roundedLine, p_band, this);
 
    fill->incRequestPosition();
  }
 
 
  void ViewportBuffer::doQueuedActions() {
    bool doNextAction = false;
 
    ViewportBufferAction *curAction = NULL;
 
    // if we aren't preserving data, and we don't still need the initial
    //   stretch (on startup), let's reset the buffer.
    if(!reinitializeActionExists() && !actionsPreserveData() &&
        p_initialStretchDone) {
      // Actions don't preserve data - call reinitialize!
      reinitialize();
    }
 
    if(!working()) {
      p_requestedFillArea = 0.0;
    }
 
    if(!p_actions->empty()) {
      curAction = p_actions->head();
      doNextAction = !curAction->started();
    }
 
    while(doNextAction) {
      if(curAction->getActionType() == ViewportBufferAction::transform) {
        doTransformAction((ViewportBufferTransform *) curAction);
      }
      else if(curAction->getActionType() == ViewportBufferAction::fill) {
        startFillAction((ViewportBufferFill *) curAction);
      }
      else {
        doStretchAction((ViewportBufferStretch *) curAction);
        p_initialStretchDone = true;
      }
 
      doNextAction = !p_actions->empty();
 
      if(doNextAction) {
        curAction = p_actions->head();
        doNextAction = !curAction->started();
      }
    }
 
    if(p_actions->empty()) {
      // Buffer Updated - Giving it BufferXYRect
      p_viewport->bufferUpdated(bufferXYRect());
    }
  }
 
 
  double ViewportBuffer::currentProgress() {
    if(!working())
      return 1.0;
    if(p_requestedFillArea <= 0.0)
      return 0.0;
 
    return 1.0 - totalUnfilledArea() / p_requestedFillArea;
  }
 
 
  double ViewportBuffer::totalUnfilledArea() {
    double totalFillArea = 0.0;
 
    // If at any time the total X or Y shift exceeds the buffer size, we aren't
    //   preserving data. Check to see if this is the case!
    for(int actionIndex = 0; actionIndex < p_actions->size(); actionIndex ++) {
      ViewportBufferAction *action = (*p_actions)[actionIndex];
 
      if(action->getActionType() == ViewportBufferAction::fill) {
        ViewportBufferFill *fill = (ViewportBufferFill *)action;
 
        QRect unfilledRect(*fill->getRect());
        unfilledRect.setTop(fill->getReadPosition());
        totalFillArea += unfilledRect.width() * unfilledRect.height();
      }
    }
 
    return totalFillArea;
  }
 
 
  bool ViewportBuffer::actionsPreserveData() {
    int totalXShift = 0;
    int totalYShift = 0;
 
    QRect currentBufferRect(bufferXYRect());
 
    int bufferWidth  = currentBufferRect.width();
    int bufferHeight = currentBufferRect.height();
 
    // If at any time the total X or Y shift exceeds the buffer size, we aren't
    //   preserving data. Check to see if this is the case!
    for(int actionIndex = 0; actionIndex < p_actions->size(); actionIndex ++) {
      ViewportBufferAction *action = (*p_actions)[actionIndex];
 
      if(action->getActionType() == ViewportBufferAction::transform) {
        ViewportBufferTransform *transform = (ViewportBufferTransform *)action;
 
        if(transform->resizeFirst()) {
          bufferWidth = transform->getBufferWidth();
          bufferHeight = transform->getBufferHeight();
        }
 
        if(abs(totalXShift) >= bufferWidth)
          return false;
        if(abs(totalYShift) >= bufferHeight)
          return false;
 
        // Without the absolute value this will calculate
        //   if any data on the screen is preserved, however
        //   a better method is to see if its quicker to reread
        //   it all which happens when we use abs
        totalXShift += abs(transform->getXTranslation());
        totalYShift += abs(transform->getYTranslation());
 
        if(!transform->resizeFirst()) {
          bufferWidth = transform->getBufferWidth();
          bufferHeight = transform->getBufferHeight();
        }
 
        if(abs(totalXShift) >= bufferWidth)
          return false;
        if(abs(totalYShift) >= bufferHeight)
          return false;
      }
    }
 
    return true;
  }
 
 
  bool ViewportBuffer::reinitializeActionExists() {
    QRect currentBufferRect(bufferXYRect());
 
    if(currentBufferRect.width() == 0 || currentBufferRect.height() == 0) {
      return true;
    }
 
    for(int actionIndex = 0; actionIndex < p_actions->size(); actionIndex ++) {
      ViewportBufferAction *action = (*p_actions)[actionIndex];
 
      if(action->getActionType() == ViewportBufferAction::transform) {
        ViewportBufferTransform *transform = (ViewportBufferTransform *)action;
 
        if(transform->getBufferWidth()  == 0)
          return true;
        if(transform->getBufferHeight() == 0)
          return true;
      }
    }
 
    return false;
  }
 
 
  bool ViewportBuffer::working() {
    return !p_actions->empty() || !p_bufferInitialized || !p_enabled;
  }
 
 
  void ViewportBuffer::doTransformAction(ViewportBufferTransform *action) {
    bool needResize = action->getBufferWidth() > -1 &&
                      action->getBufferHeight() > -1;
 
    if(action->resizeFirst() && needResize) {
      resizeBuffer(action->getBufferWidth(), action->getBufferHeight());
    }
 
    shiftBuffer(action->getXTranslation(), action->getYTranslation());
 
    if(!action->resizeFirst() && needResize) {
      resizeBuffer(action->getBufferWidth(), action->getBufferHeight());
    }
 
    delete action;
    action = NULL;
    p_actions->dequeue();
  }
 
 
  void ViewportBuffer::startFillAction(ViewportBufferFill *action) {
    if(action->started())
      return;
 
    action->started(true);
 
    requestCubeLine(action);
 
    if(action->shouldRequestMore()) {
      requestCubeLine(action);
    }
  }
 
 
  void ViewportBuffer::doStretchAction(ViewportBufferStretch *action) {
    delete action;
    action = NULL;
    p_actions->dequeue();
 
    p_viewport->restretch(this);
  }
 
 
  void ViewportBuffer::resizeBuffer(unsigned int width, unsigned int height) {
    p_buffer.resize(height);
 
    for(unsigned int i = 0; i < p_buffer.size(); i++) {
      p_buffer[i].resize(width, Null);
    }
  }
 
 
  void ViewportBuffer::shiftBuffer(int deltaX, int deltaY) {
    if(deltaY >= 0) {
      for(int i = p_buffer.size() - 1; i >= deltaY; i--) {
        p_buffer[i] = p_buffer[i - deltaY];
 
        // If we have y shift, null out original data (keep only moved data)
        if(deltaY != 0) {
          for(unsigned int x = 0; x < p_buffer[i - deltaY].size(); x++) {
            p_buffer[i - deltaY][x] = Null;
          }
        }
 
        if(deltaX > 0) {
          for(int j = p_buffer[i].size() - 1; j >= deltaX; j--) {
            p_buffer[i][j] = p_buffer[i][j - deltaX];
            p_buffer[i][j - deltaX] = Null;
          }
        }
        else if(deltaX < 0) {
          for(int j = 0; j < (int)p_buffer[i].size() + deltaX; j++) {
            p_buffer[i][j] = p_buffer[i][j - deltaX];
            p_buffer[i][j - deltaX] = Null;
          }
        }
      }
    }
    else if(deltaY < 0) {
      for(int i = 0; i < (int)p_buffer.size() + deltaY; i++) {
        p_buffer[i] = p_buffer[i - deltaY];
 
        // null out original data (keep only moved data)
        for(unsigned int x = 0; x < p_buffer[i - deltaY].size(); x++) {
          p_buffer[i - deltaY][x] = Null;
        }
 
        if(deltaX > 0) {
          for(int j = p_buffer[i].size() - 1; j >= deltaX; j--) {
            p_buffer[i][j] = p_buffer[i][j - deltaX];
            p_buffer[i][j - deltaX] = Null;
          }
        }
        else if(deltaX < 0) {
          for(int j = 0; j < (int)p_buffer[i].size() + deltaX; j++) {
            p_buffer[i][j] = p_buffer[i][j - deltaX];
            p_buffer[i][j - deltaX] = Null;
          }
        }
      }
    }
  }
 
 
  void ViewportBuffer::resizedViewport() {
    updateBoundingRects();
 
    if(!p_bufferInitialized || !p_enabled)
      return;
 
    // ensure we have a valid bounding rect!  For example, If the cube viewport
    // is hidden and then shown again this could happen.
    if(!p_XYBoundingRect.isValid())
      return;
 
    if(!p_oldXYBoundingRect.isValid()) {
      reinitialize();
      return;
    }
 
    //We need to know how much data was gained/lost on each side of the cube
    double deltaLeftSamples =  p_sampLineBoundingRect[rectLeft] -
                               p_oldSampLineBoundingRect[rectLeft];
    //The input to round should be close to an integer
    int deltaLeftPixels = (int)round(deltaLeftSamples * p_viewport->scale());
 
    double deltaRightSamples = p_sampLineBoundingRect[rectRight] -
                               p_oldSampLineBoundingRect[rectRight];
    int deltaRightPixels = (int)round(deltaRightSamples * p_viewport->scale());
 
    double deltaTopSamples = p_sampLineBoundingRect[rectTop] -
                             p_oldSampLineBoundingRect[rectTop];
    int deltaTopPixels = (int)round(deltaTopSamples * p_viewport->scale());
 
    double deltaBottomSamples = p_sampLineBoundingRect[rectBottom] -
                                p_oldSampLineBoundingRect[rectBottom];
    int deltaBottomPixels = (int)round(deltaBottomSamples *
                                       p_viewport->scale());
 
    //deltaW is the change in width in the visible area of the cube
    int deltaW = - deltaLeftPixels + deltaRightPixels;
 
    //deltaH is the change in height in the visible area of the cube
    int deltaH = - deltaTopPixels + deltaBottomPixels;
 
    //If the new visible width has changed (resized in the horizontal direction)
    if(p_XYBoundingRect.width() != p_oldXYBoundingRect.width()) {
      //Resized larger in the horizontal direction
      if(deltaW > 0) {
        //Using old height because we might lose data if new height is smaller
        ViewportBufferTransform *transform = new ViewportBufferTransform();
        transform->setTranslation(-deltaLeftPixels, 0);
        transform->setResize(p_XYBoundingRect.width(),
                             p_oldXYBoundingRect.height());
        transform->resizeFirst(true);
 
        enqueueAction(transform);
 
        // left side that needs filled
        QPoint topLeftOfLeftRect(p_XYBoundingRect.left(),
                                 p_oldXYBoundingRect.top());
 
        QPoint bottomRightOfLeftRect(p_XYBoundingRect.left() - deltaLeftPixels,
                                     p_oldXYBoundingRect.bottom());
 
        QRect leftRect(topLeftOfLeftRect, bottomRightOfLeftRect);
 
        ViewportBufferFill *leftFill = createViewportBufferFill(leftRect,
                                       true);
        enqueueAction(leftFill);
 
        // right side that needs filled
        QPoint topLeftOfRightRect(p_XYBoundingRect.right() - deltaRightPixels,
                                  p_oldXYBoundingRect.top());
 
        QPoint bottomRightOfRightRect(p_XYBoundingRect.right(),
                                      p_oldXYBoundingRect.bottom());
 
        QRect rightRect(topLeftOfRightRect, bottomRightOfRightRect);
 
        ViewportBufferFill *rightFill = createViewportBufferFill(rightRect,
                                        true);
        enqueueAction(rightFill);
      }
      //Resized smaller in the horizontal direction
      else if(deltaW < 0) {
        ViewportBufferTransform *transform = new ViewportBufferTransform();
        transform->setTranslation(-deltaLeftPixels, 0);
        transform->setResize(p_XYBoundingRect.width(),
                             p_oldXYBoundingRect.height());
        transform->resizeFirst(false);
        enqueueAction(transform);
      }
    }
 
    //If the new visible height has changed (resized in the vertical direction)
    if(p_XYBoundingRect.height() != p_oldXYBoundingRect.height()) {
      //Resized larger in the vertical direction
      if(deltaH > 0) {
        ViewportBufferTransform *transform = new ViewportBufferTransform();
        transform->setTranslation(0, -deltaTopPixels);
        transform->setResize(p_XYBoundingRect.width(),
                             p_XYBoundingRect.height());
        transform->resizeFirst(true);
 
        enqueueAction(transform);
 
        QPoint bottomRightOfTopSide(p_XYBoundingRect.right(),
                                    p_XYBoundingRect.top() - deltaTopPixels);
 
        QRect topSideToFill(p_XYBoundingRect.topLeft(), bottomRightOfTopSide);
 
 
        QPoint topLeftOfbottomSide(p_XYBoundingRect.left(),
                                   p_XYBoundingRect.bottom() -
                                   deltaBottomPixels);
 
        QRect bottomSideToFill(topLeftOfbottomSide,
                               p_XYBoundingRect.bottomRight());
 
        ViewportBufferFill *topFill = createViewportBufferFill(topSideToFill,
                                      false);
        enqueueAction(topFill);
 
        ViewportBufferFill *bottomFill =
          createViewportBufferFill(bottomSideToFill, false);
        enqueueAction(bottomFill);
      }
      //Resized smaller in the vertical direction
      else if(deltaH < 0) {
        ViewportBufferTransform *transform = new ViewportBufferTransform();
 
        transform->setTranslation(0, -deltaTopPixels);
        transform->setResize(p_XYBoundingRect.width(),
                             p_oldXYBoundingRect.height());
 
        enqueueAction(transform);
      }
    }
 
    doQueuedActions();
  }
 
 
  void ViewportBuffer::pan(int deltaX, int deltaY) {
    updateBoundingRects();
 
    if(!p_bufferInitialized || !p_enabled) {
      return;
    }
 
 
    if(p_sampLineBoundingRect == p_oldSampLineBoundingRect) {
      //The sample line bounding rect contains the bounds of the
      //screen pixels to the cube sample/line bounds. If the cube
      //bounds do not change, then we do not need to do anything to
      //the buffer.
      return;
    }
 
    double deltaLeftSamples = p_sampLineBoundingRect[rectLeft] -
                              p_oldSampLineBoundingRect[rectLeft];
    int deltaLeftPixels = (int)round(deltaLeftSamples * p_viewport->scale());
 
    double deltaTopLines = p_sampLineBoundingRect[rectTop] -
                           p_oldSampLineBoundingRect[rectTop];
    int deltaTopPixels = (int)round(deltaTopLines * p_viewport->scale());
 
    // Don't try to figure out panning beyond a full screen,
    //   even though data could very well be preserved.
    if(abs(deltaY) >= p_XYBoundingRect.height() ||
        abs(deltaX) >= p_XYBoundingRect.width()) {
      reinitialize();
      return;
    }
 
    //Left side of the visible area changed (start sample is different)
    if(p_sampLineBoundingRect[rectLeft] != p_oldSampLineBoundingRect[rectLeft]) {
      //Shifting data to the right
      if(deltaX > 0) {
        // The buffer is getting bigger
        ViewportBufferTransform *transform = new ViewportBufferTransform();
        transform->setResize(p_XYBoundingRect.width(),
                             p_oldXYBoundingRect.height());
        transform->setTranslation(-deltaLeftPixels, 0);
        transform->resizeFirst(true);
 
        enqueueAction(transform);
 
        QPoint topLeftOfRefill(p_XYBoundingRect.left(),
                               p_oldXYBoundingRect.top());
 
        QPoint bottomRightOfRefill(p_XYBoundingRect.left() + deltaX,
                                   p_oldXYBoundingRect.bottom());
        QRect fillArea(topLeftOfRefill, bottomRightOfRefill);
 
        ViewportBufferFill *fill = createViewportBufferFill(fillArea, true);
        enqueueAction(fill);
      }
      //Shifting data to the left
      else if(deltaX < 0) {
        //The buffer is getting smaller - no new data
        ViewportBufferTransform *transform = new ViewportBufferTransform();
        transform->setTranslation(-deltaLeftPixels, 0);
        transform->setResize(p_XYBoundingRect.width(),
                             p_oldXYBoundingRect.height());
        transform->resizeFirst(false);
        enqueueAction(transform);
 
        // if new samples on the screen at all, mark it for reading
        if(p_sampLineBoundingRect[rectRight] !=
            p_oldSampLineBoundingRect[rectRight]) {
          QPoint topLeftOfRefill(p_XYBoundingRect.right() + deltaX,
                                 p_oldXYBoundingRect.top());
          QPoint bottomRightOfRefill(p_XYBoundingRect.right(),
                                     p_oldXYBoundingRect.bottom());
 
          QRect refillArea(topLeftOfRefill, bottomRightOfRefill);
 
          ViewportBufferFill *fill = createViewportBufferFill(refillArea,
                                     true);
          enqueueAction(fill);
        }
      }
    }
    // Left side of the visible area is the same (start sample has not changed,
    // but end sample may be different)
    else {
      ViewportBufferTransform *transform = new ViewportBufferTransform();
      transform->setResize(p_XYBoundingRect.width(),
                           p_oldXYBoundingRect.height());
      enqueueAction(transform);
 
      if(deltaX < 0) {
        QPoint topLeftOfFillArea(p_XYBoundingRect.right() + deltaX,
                                 p_oldXYBoundingRect.top());
 
        QPoint bottomRightOfFillArea(p_XYBoundingRect.right(),
                                     p_oldXYBoundingRect.bottom());
 
        QRect fillArea(topLeftOfFillArea, bottomRightOfFillArea);
        ViewportBufferFill *fill = createViewportBufferFill(fillArea, true);
 
        enqueueAction(fill);
      }
    }
 
    //Top side of the visible area changed (start line is different)
    if(p_sampLineBoundingRect[rectTop] != p_oldSampLineBoundingRect[rectTop]) {
      //Shifting data down
      if(deltaY > 0) {
        ViewportBufferTransform *transform = new ViewportBufferTransform();
        transform->setTranslation(0, -deltaTopPixels);
        transform->setResize(p_XYBoundingRect.width(),
                             p_XYBoundingRect.height());
        transform->resizeFirst(true);
        enqueueAction(transform);
 
        QPoint topLeftOfFillArea(p_XYBoundingRect.left(),
                                 p_XYBoundingRect.top());
        QPoint bottomRightOfFillArea(p_XYBoundingRect.right(),
                                     p_XYBoundingRect.top() + deltaY);
        QRect fillArea(topLeftOfFillArea, bottomRightOfFillArea);
        ViewportBufferFill *fill = createViewportBufferFill(fillArea, false);
        enqueueAction(fill);
      }
      //Shifting data up
      else if(deltaY < 0) {
        ViewportBufferTransform *transform = new ViewportBufferTransform();
        transform->setTranslation(0, -deltaTopPixels);
        transform->setResize(p_XYBoundingRect.width(),
                             p_XYBoundingRect.height());
        transform->resizeFirst(false);
        enqueueAction(transform);
 
        // if new lines on the screen at all, mark it for reading
        if(p_sampLineBoundingRect[rectBottom] !=
            p_oldSampLineBoundingRect[rectBottom]) {
          QPoint topLeftOfFillArea(p_XYBoundingRect.left(),
                                   p_oldXYBoundingRect.bottom() + deltaY);
          QPoint bottomRightOfFillArea(p_XYBoundingRect.right(),
                                       p_XYBoundingRect.bottom());
          QRect fillArea(topLeftOfFillArea, bottomRightOfFillArea);
          ViewportBufferFill *fill = createViewportBufferFill(fillArea, false);
          enqueueAction(fill);
        }
      }
    }
    // Top side of the visible area is the same (start line has not changed, but
    // end line may be different)
    else {
      ViewportBufferTransform *transform = new ViewportBufferTransform();
      transform->setResize(p_XYBoundingRect.width(),
                           p_XYBoundingRect.height());
      enqueueAction(transform);
 
      if(deltaY < 0) {
        QPoint topLeftOfFillArea(p_XYBoundingRect.left(),
                                 p_XYBoundingRect.bottom() + deltaY);
        QPoint bottomRightOfFillArea(p_XYBoundingRect.right(),
                                     p_XYBoundingRect.bottom());
        QRect fillArea(topLeftOfFillArea, bottomRightOfFillArea);
        ViewportBufferFill *fill = createViewportBufferFill(fillArea, false);
        enqueueAction(fill);
      }
    }
 
    doQueuedActions();
  }
 
 
  void ViewportBuffer::addStretchAction() {
    for(int i = 0; i < p_actions->size(); i++) {
      if((*p_actions)[i]->getActionType() == ViewportBufferAction::stretch) {
        p_actions->removeAt(i);
        i --;
      }
    }
 
    enqueueAction(new ViewportBufferStretch());
    doQueuedActions();
  }
 
  void ViewportBuffer::emptyBuffer(bool force) {
    if(force) {
      p_buffer.clear();
      p_bufferInitialized = false;
    }
  }
 
 
  QRect ViewportBuffer::bufferXYRect() {
    QRect rect = p_XYBoundingRect;
 
    if(!rect.height() || !p_buffer.size())
      return QRect();
 
    if(rect.height() > (int) p_buffer.size())
      rect.setBottom(rect.top() + p_buffer.size() - 1);
 
    if(rect.width() > (int) p_buffer[0].size())
      rect.setRight(rect.left() + p_buffer[0].size() - 1);
 
    return rect;
  }
 
 
  void ViewportBuffer::scaleChanged() {
    if(!p_enabled)
      return;
 
    try {
      updateBoundingRects();
      reinitialize();
    }
    catch (IException &e) {
      throw IException(
          e, IException::Programmer, "Unable to change scale.", _FILEINFO_);
    }
  }
 
 
  void ViewportBuffer::enable(bool enabled) {
    bool wasEnabled = p_enabled;
 
    p_enabled = enabled;
 
    if(!wasEnabled && p_enabled) {
      updateBoundingRects();
      reinitialize();
    }
  }
 
 
  void ViewportBuffer::setBand(int band) {
    if(p_band == band)
      return;
    p_band = band;
 
    updateBoundingRects();
 
    if(!p_enabled)
      return;
 
    reinitialize();
  }
 
 
  void ViewportBuffer::reinitialize() {
 
    try {
      // If we're in the middle of a process, we got an okay stretch on startup,
      // then we can stop what we're doing.
      if(working() && p_initialStretchDone) {
        // We only need to handle the current action, can ignore others
        ViewportBufferAction *curAction = p_actions->head();
 
        // Delete older actions
        for(int i = p_actions->size() - 1; i > 0; i--) {
          delete(*p_actions)[i];
          p_actions->pop_back();
        }
 
        // Deal with current action
        if(curAction->started()) {
          if(curAction->getActionType() == ViewportBufferAction::fill) {
            ViewportBufferFill *fill = (ViewportBufferFill *)curAction;
 
            fill->stop();
 
            p_requestedFillArea = fill->getRect()->height() *
                                  fill->getRect()->width();
          }
        }
        else {
          delete curAction;
          p_actions->clear();
          p_requestedFillArea = 0.0;
        }
      }
 
 
      p_bufferInitialized = true;
 
      ViewportBufferTransform *reset = new ViewportBufferTransform();
      reset->setResize(0, 0);
      enqueueAction(reset);
 
      if (p_XYBoundingRect.isValid()) {
        ViewportBufferTransform *transform = new ViewportBufferTransform();
        transform->setResize(p_XYBoundingRect.width(), p_XYBoundingRect.height());
        enqueueAction(transform);
        ViewportBufferFill *fill = createViewportBufferFill(p_XYBoundingRect,
                                   false);
        enqueueAction(fill);
      }
 
      doQueuedActions();
    }
    catch (IException &e) {
      throw IException(IException::Programmer,
                       "Unable to resize and fill buffer.",
                       _FILEINFO_);
    }
  }
}