#include <addPhotosDialog.h>

Inheritance diagram for GeneratePreviewThread:

Collaboration diagram for GeneratePreviewThread:

Public Member Functions
	GeneratePreviewThread (FilePreview *previewWidget)
void	start (QString filename)
virtual void	run ()
Private Attributes
QString	filename
	current file being processed
FilePreview *	previewWidget
	handle on preview widget necessary for posting an update event once the current file has been processed
bool	updating
	is the worker thread currently generating a file preview?
QString	queue
	next file to be processed by worker thread
QMutex	lockingMutex
	locking mutex - necessary to prevent multiple threads from accessing the updating bool or queue variable simultaniously

Detailed Description

Definition at line 29 of file addPhotosDialog.h.

Constructor & Destructor Documentation

GeneratePreviewThread::GeneratePreviewThread ( FilePreview * previewWidget )

Definition at line 60 of file addPhotosDialog.cpp.

References previewWidget, queue, and updating.

{
  //we'll need to store a previewWidget handle to 
  //posting update events when updates are
  //ready to be shown
  this->previewWidget = previewWidget;

  //by default worker thread isn't busy yet
  updating = false;
  queue = QString::null;
}

Member Function Documentation

void GeneratePreviewThread::run ( ) [virtual]

Definition at line 94 of file addPhotosDialog.cpp.

References filename, getImageSize(), lockingMutex, MIN_HEIGHT, MIN_WIDTH, previewWidget, queue, scaleImage(), and updating.

{
  //since it is possible for another job
  //to be added to the queue while processing this one, it is necessary
  //to loop until the queue is empty
  while(true)
  {
    //------------------------------------------
    //Get image type extension and convert to caps  
    QString extension = QFileInfo(filename).extension(false).upper();
    bool validExtension = ( (extension.compare("GIF") == 0) ||
                            (extension.compare("JPG") == 0) ||
                            (extension.compare("JPEG") == 0) ||
                            (extension.compare("PNG") == 0) ||
                            (extension.compare("XPM") == 0) );
    //------------------------------------------
    //Scale the image to fit nicely on the screen, aka < 300x225
    QImage scaledImage;
    if( validExtension )
    {
      scaleImage(filename, scaledImage, MIN_WIDTH, MIN_HEIGHT );
    }
    //------------------------------------------
    //Get image resolution
    QString imageRes = "";
    if(validExtension)
    {
      QSize res;
      getImageSize( filename, res );
      imageRes = QString("%1 x %2").arg(res.width()).arg(res.height());
    }
    //------------------------------------------
    //Determine file size and construct a nicely formatted size string
    QString fileSize = "?";
    QFileInfo info;
    info.setFile( filename );
    int sizeOnDisk = info.size();
    
    if(sizeOnDisk < 1024)
      fileSize = QString("%1 Byte%2").arg(sizeOnDisk).arg( sizeOnDisk == 0 || sizeOnDisk > 1 ? "s" : "");
    else if( sizeOnDisk/1024 < 1024)
      //    fileSize = QString("%1 Kb").arg( ((float)*sizeOnDisk)/1024 );
      fileSize = QString("%1 Kb").arg( ((float)((100*sizeOnDisk)/1024))/100 );
    else if( sizeOnDisk/(1024*1024) < 1024)
      fileSize = QString("%1 Mb").arg( ((float)((100*sizeOnDisk)/(1024*1024)))/100 );
    else
      fileSize = QString("%1 Gigs").arg( ((float)((100*sizeOnDisk)/(1024*1024*1024)))/100 );   
    //------------------------------------------
    //Setup image details string  
    QString fileDetails = QString("%1 %2, %3")
                                  .arg(imageRes)
                                  .arg(extension)
                                  .arg(fileSize);
    //------------------------------------------
    //Post UPDATE_PREVIEW_DETAILS event
    UpdatePreviewEvent* upe = new UpdatePreviewEvent( scaledImage, fileDetails );
    QApplication::postEvent( previewWidget, upe );
    //------------------------------------------
    //get lock
    lockingMutex.lock();
    
    //if the queue is empty we're done!
    if( queue.isNull() )
    {
      updating = false;
      lockingMutex.unlock();
      return; 
    }
    //clear queue and process pending job
    else
    {
      filename = queue;
      queue = QString::null;
      lockingMutex.unlock();
    }
    
  } //end while(true)
}

void GeneratePreviewThread::start ( QString filename )

Definition at line 72 of file addPhotosDialog.cpp.

References filename, lockingMutex, queue, and updating.

Referenced by FilePreview::updatePreview().

{
  //get lock
  lockingMutex.lock();
  
  //if currently animating then append job to queue
  if(updating)
  {
    queue = filename;
    lockingMutex.unlock();
    return; 
  }
  //else set animating to true, actually initiate job
  else
  {
    updating = true;
    this->filename = filename;
    lockingMutex.unlock();
    QThread::start();
  }
}