GeneratePreviewThread Class Reference

#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 33 of file addPhotosDialog.h.

Constructor & Destructor Documentation

GeneratePreviewThread()

GeneratePreviewThread::GeneratePreviewThread

(

FilePreview *

previewWidget

)

Definition at line 63 of file addPhotosDialog.cpp.

{
  //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;
}

References previewWidget, queue, and updating.

Member Function Documentation

run()

void GeneratePreviewThread::run ( )

virtual

Definition at line 97 of file addPhotosDialog.cpp.

{
  //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)
}

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

start()

void GeneratePreviewThread::start

(

QString

filename

)

Definition at line 75 of file addPhotosDialog.cpp.

{
  //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();
  }
}

References filename, lockingMutex, queue, and updating.

Referenced by FilePreview::updatePreview().

Member Data Documentation

filename

QString GeneratePreviewThread::filename

private

current file being processed

Definition at line 42 of file addPhotosDialog.h.

Referenced by run(), and start().

lockingMutex

QMutex GeneratePreviewThread::lockingMutex

private

locking mutex - necessary to prevent multiple threads from accessing the updating bool or queue variable simultaniously

Definition at line 56 of file addPhotosDialog.h.

Referenced by run(), and start().

previewWidget

FilePreview* GeneratePreviewThread::previewWidget

private

handle on preview widget necessary for posting an update event once the current file has been processed

Definition at line 46 of file addPhotosDialog.h.

Referenced by GeneratePreviewThread(), and run().

queue

QString GeneratePreviewThread::queue

private

next file to be processed by worker thread

Definition at line 52 of file addPhotosDialog.h.

Referenced by GeneratePreviewThread(), run(), and start().

updating

bool GeneratePreviewThread::updating

private

is the worker thread currently generating a file preview?

Definition at line 49 of file addPhotosDialog.h.

Referenced by GeneratePreviewThread(), run(), and start().

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The documentation for this class was generated from the following files:

• addPhotosDialog.h
• addPhotosDialog.cpp