Generating image from message structure

[m_jero]

Hi,
I'm creating an app that according with some messages received will create a grayscale image.
Every message contains the color information for a rectangle that is part of the complete image coded to 8 bits (the complete image is 2048 x 2048 pixels).

I need 2 differents methods to show this messages:

• One that is a kind of "play mode" where everything received will be played.
• Anotherone where you can show message by message.

Now, I'm using a queue,where I store every message I receive:

{
    m_mutex.lock();
    m_queue.enqueue(message);
    m_mutex.unlock();
}

bool MessagesDB::isEmpty()
{
    return m_queue.isEmpty();
}

bool MessagesDB::getMessage(RVMessage& message)
{
    if (!isEmpty())
    {
	m_mutex.lock();
	message = m_queue.dequeue();
	m_mutex.unlock();

	return true;
    }
    return false;
}

Then from the MainWindow process I call the different methods to generate the image in a different thread:

#include "MainWindow.h"

#include <MessagesDB.h>
#include <utils.h>
#include <iostream>
#include <WApp.h>

MainWindow::MainWindow(QWidget *parent) :
    QWidget(parent),
    m_timer()
{
    setWindowTitle("Afl Raw Video Output Testsuite");

    m_layoutV = new QVBoxLayout();
    m_layoutV->setContentsMargins(0, 0, 0, 0);
    m_layoutV->setSpacing(0);

    m_layoutScrollArea = new QVBoxLayout();
    m_layoutScrollArea->setContentsMargins(0, 0, 0, 0);
    m_layoutScrollArea->setSpacing(0);

    m_layoutH = new QHBoxLayout();
    m_layoutH->setContentsMargins(0, 0, 0, 0);
    m_layoutH->setSpacing(0);

    m_layoutVToolbar = new QVBoxLayout();
    m_layoutVToolbar->setContentsMargins(0, 0, 0, 0);
    m_layoutVToolbar->setSpacing(0);

    m_gridLayout = new QGridLayout();
    m_gridLayout->setSpacing(8);
    m_gridLayout->setRowStretch(0, 1);
    m_gridLayout->setRowStretch(1, 1);
    m_gridLayout->setRowStretch(2, 1);
    m_gridLayout->setRowStretch(3, 1);

    m_scrollArea = new QScrollArea();
    m_scrollArea->setFixedSize(QSize(1220, 820));

    img = new QLabel();
    img->setFixedSize(QSize(2048, 2048));
    m_scrollArea->setWidget(img);

    m_scrollArea->setLayout(m_layoutScrollArea);

    m_layoutV->addWidget(m_scrollArea);


    runButton = new QPushButton("Next");
    m_layoutVToolbar->addWidget(runButton);

    playButton = new QPushButton("Play");
    m_layoutVToolbar->addWidget(playButton);

    m_layoutH->addLayout(m_layoutVToolbar);
    m_layoutH->setStretch(0,1);
    m_layoutH->addLayout(m_gridLayout);
    m_layoutH->setStretch(1,1);

    m_layoutV->addLayout(m_layoutH);
    setLayout(m_layoutV);

    // the QImage generation thread

    qRegisterMetaType<QImage>("QImage");
    m_generateImageThread = new GenerateImageThread();

    // slot to respond to the QImage generation thread
    // - display the image in a window

    connect(runButton, SIGNAL(clicked()),
            this, SLOT(generateImage()));

    connect(playButton, SIGNAL(clicked()),
            this, SLOT(playMode()));

    connect(m_generateImageThread, SIGNAL(imageReady(const QImage &)),
            this, SLOT(displayImage(const QImage &)));

    m_timer = new QTimer();
    m_timer->setInterval(20);
    connect(m_timer,SIGNAL(timeout()),this,SLOT(generateImage()));
}

MainWindow::~MainWindow()
{
    if (img)
        delete img;
}

//--------------------
// slot to run thread
//-------------------

void MainWindow::generateImage()
{
   if (!m_generateImageThread->isRunning())
   {
       m_generateImageThread->start();
   }
}

//--------------------
// Play mode
//-------------------

void MainWindow::playMode()
{
    if (!m_timer->isActive())
    {
	m_timer->start();
	playButton->setText("Stop");
    }
    else
    {
	m_timer->stop();
	playButton->setText("Start");
    }
}

//-------------------
// display the QImage
//-------------------

void MainWindow::displayImage(const QImage &image)
{
   img->setPixmap(QPixmap::fromImage(image));
}

As you can see, for running the "play mode" I have created a timer that runs/stops when you press the button.

And this is the thread that generates the image:

GenerateImageThread::GenerateImageThread(QObject *parent)
 : QThread(parent),
   m_image(MAX_X, MAX_Y, QImage::Format_RGB32)
{
    //Initialize colors
    for (int i = 0; i < MAX_COLORS;++i)
    {
	m_colors[i] = QColor(i, i, i);
    }
}

void GenerateImageThread::run()
{
    RVMessage message(RVMessage::E_8BITS_PIXEL);

    while (MessagesDB::Instance().getMessage(message))
    {
	int width = message.getRightCoord() - message.getLeftCoord() + 1;
	int height = message.getBottomCoord() - message.getTopCoord() + 1;

	for (int i = 0; i < width; ++i)
	{
	    for (int j = 0; j < height; ++j)
	    {
		m_image.setPixel(i + message.getLeftCoord(),
			j + message.getTopCoord(),
			m_colors[message.getData(i, j)].rgb());
	    }
	}
	emit imageReady(m_image);
    }
}

My two main problems are that first, I am not getting the best performance results while running this. Do you have any idea about how to improve this.
And second, I am gonna have the need to send certain information from the messages (header information) to the main window apart of the image. Do you think is a good idea to send a new signal with this information?

Thanks in advance

[SGaist]

Hi,

Are you generating the RVMessage ?