This post shows a form control widget that performs validation on its input. The invalid input is highlighted in red and the error message is display below the input. The input is validated in real-time (as the text is changed) when invalid the submit button is disabled and when valid it is enabled. The desired effect is shown below:
This post demonstrates how to create custom tabs using QPushButtons in a QButtonGroup. The code below is self explanatory, the button group ensures that only a single button can be selected at one time. The buttons are made to look more like tabs using QT style sheet and the final result is shown below
There is no API to insert a checkbox into the header of a QTableView. The recommended way of achieving this is to subclass the QHeaderView and draw the checkbox in the paintSection() method which is in my opinion overkill for such a simple feature.
In this post, I show how to achieve a similar effect by simply adding icons in the header. The desired effect is shown below:
import cv2
from math import atan, pi, ceil
img = cv2.imread('mask3.jpg', 0)
h,w = img.shape[:2]
cv2.imshow('original', img)
m = cv2.moments(img)
# You can read about Image Moments
# Chapter 18 Shape analysis - Page 633
# Digital Image Processing 4th Edition By William K. Pratt
# OR http://en.wikipedia.org/wiki/Image_moment
x = m['m10']/m['m00']
y = m['m01']/m['m00']
mu02 = m['mu02']
mu20 = m['mu20']
mu11 = m['mu11']
lambda1 = 0.5*( mu20 + mu02 ) + 0.5*( mu20**2 + mu02**2 - 2*mu20*mu02 + 4*mu11**2 )**0.5
lambda2 = 0.5*( mu20 + mu02 ) - 0.5*( mu20**2 + mu02**2 - 2*mu20*mu02 + 4*mu11**2 )**0.5
lambda_m = max(lambda1, lambda2)
# Convert from radians to degrees
angle = atan((lambda_m - mu20)/mu11)*180/pi
print angle
# Create a rotation matrix and use it to de-skew the image.
center = tuple(map(int, (x, y)))
rotmat = cv2.getRotationMatrix2D(center, angle , 1)
rotatedImg = cv2.warpAffine(img, rotmat, (w, h), flags = cv2.INTER_CUBIC)
cv2.imshow('final', rotatedImg)
cv2.waitKey()
| Original Image | De-skewed Image | Orientation (degree) |
|---|---|---|
 |
 |
-89.99 |
 |
|
-0.0 |
 |
 |
-39.03 |
 |
 |
46.95 |
 |
 |
3.57 |
#ifndef PLAYER_H
#ifndef PLAYER_H
#define PLAYER_H
#include <QMutex>
#include <QThread>
#include <QImage>
#include <QWaitCondition>
#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;
class Player : public QThread
{ Q_OBJECT
private:
....
VideoCapture *capture;
Mat RGBframe;
QImage img;
signals:
......
protected:
......
public:
.......
//set video properties
void setCurrentFrame( int frameNumber);
//Get video properties
double getFrameRate();
double getCurrentFrame();
double getNumberOfFrames();
};
#endif // VIDEOPLAYER_H
bool Player::loadVideo(string filename) {
capture = new cv::VideoCapture(filename);
if (capture->isOpened())
{
frameRate = (int) capture->get(CV_CAP_PROP_FPS);
return true;
}
else
return false;
}
void Player::run()
{
int delay = (1000/frameRate);
while(!stop){
if (!capture->read(frame))
{
stop = true;
}
.....
}
}
double Player::getCurrentFrame(){
return capture->get(CV_CAP_PROP_POS_FRAMES);
}
double Player::getNumberOfFrames(){
return capture->get(CV_CAP_PROP_FRAME_COUNT);
}
double Player::getFrameRate(){
return frameRate;
}
void Player::setCurrentFrame( int frameNumber )
{
capture->set(CV_CAP_PROP_POS_FRAMES, frameNumber);
}
Player::~Player()
{
mutex.lock();
stop = true;
capture.release();
delete capture;
condition.wakeOne();
mutex.unlock();
wait();
}
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QFileDialog>
#include <QMessageBox>
#include <player.h>
#include <QTime>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
.......
private slots:
.........
QString getFormattedTime(int timeInSeconds);
void on_horizontalSlider_sliderPressed();
void on_horizontalSlider_sliderReleased();
void on_horizontalSlider_sliderMoved(int position);
private:
........
};
#endif // MAINWINDOW_H
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
.......
ui->pushButton_2->setEnabled(false);
ui->horizontalSlider->setEnabled(false);
}
void MainWindow::updatePlayerUI(QImage img)
{
if (!img.isNull())
{
ui->label->setAlignment(Qt::AlignCenter);
ui->label->setPixmap(QPixmap::fromImage(img).scaled(ui->label->size(),
Qt::KeepAspectRatio, Qt::FastTransformation));
ui->horizontalSlider->setValue(myPlayer->getCurrentFrame());
ui->label_2->setText( getFormattedTime( (int)myPlayer->getCurrentFrame()/(int)myPlayer->getFrameRate()) );
}
}
void MainWindow::on_pushButton_clicked()
{
QString filename = QFileDialog::getOpenFileName(this,
tr("Open Video"), ".",
tr("Video Files (*.avi *.mpg *.mp4)"));
QFileInfo name = filename;
if (!filename.isEmpty()){
if (!myPlayer->loadVideo(filename.toAscii().data()))
{
QMessageBox msgBox;
msgBox.setText("The selected video could not be opened!");
msgBox.exec();
}
else{
this->setWindowTitle(name.fileName());
ui->pushButton_2->setEnabled(true);
ui->horizontalSlider->setEnabled(true);
ui->horizontalSlider->setMaximum(myPlayer->getNumberOfFrames());
ui->label_3->setText( getFormattedTime( (int)myPlayer->getNumberOfFrames()/(int)myPlayer->getFrameRate()) );
}
}
}
QString MainWindow::getFormattedTime(int timeInSeconds){
int seconds = (int) (timeInSeconds) % 60 ;
int minutes = (int) ((timeInSeconds / 60) % 60);
int hours = (int) ((timeInSeconds / (60*60)) % 24);
QTime t(hours, minutes, seconds);
if (hours == 0 )
return t.toString("mm:ss");
else
return t.toString("h:mm:ss");
}
void MainWindow::on_horizontalSlider_sliderPressed()
{
myPlayer->Stop();
}
void MainWindow::on_horizontalSlider_sliderReleased()
{
myPlayer->Play();
}
void MainWindow::on_horizontalSlider_sliderMoved(int position)
{
myPlayer->setCurrentFrame(position);
ui->label_2->setText( getFormattedTime( position/(int)myPlayer->getFrameRate()) );
}
<wizard version="1" kind="project"
class="qt4project" firstpage="10"
id="A.customqtproject" category="B.CustomProjects">
<icon>console.png</icon>
<description>Creates a custom Qt project which allows you to include external libraries.</description>
<displayname>Custom QT Projects</displayname>;
<displaycategory>Custom Projects</displaycategory>
<files>
<file source="main.cpp" openeditor="true"/>
<file source="mainwindow.cpp" openeditor="false"/>
<file source="mainwindow.h" openeditor="false"/>
<file source="mainwindow.ui" openeditor="false"/>
<file source="project.pro" target="%ProjectName%.pro" openproject="true"/>
</files>
<!-- Create a 2nd wizard page with parameters -->
<fieldpagetitle>Add External Libraries</fieldpagetitle>
<fields>
<field name="OPENCV">
<fieldcontrol class="QCheckBox" truevalue="" falsevalue="# "/>
<fielddescription>Include OpenCV Libraries</fielddescription>
</field>
<field name="QWT">
<fieldcontrol class="QCheckBox" truevalue="" falsevalue="# "/>
<fielddescription>Include QWT Libraries</fielddescription>
</field>
</fields>
</wizard>
# Opencv Library %OPENCV%INCLUDEPATH += "/usr/local/include/opencv2" %OPENCV%LIBS += `pkg-config --cflags --libs opencv` # Qwt library %QWT%CONFIG += qwt %QWT%INCLUDEPATH +="/usr/local/qwt-6.1.0-rc3/include" %QWT%LIBS += -L/usr/local/qwt-6.1.0-rc3/lib -lqwt
# Install python cd $OPENSHIFT_TMP_DIR wget http://python.org/ftp/python/2.7.3/Python-2.7.3.tar.bz2 tar jxf Python-2.7.3.tar.bz2 cd Python-2.7.3 ./configure --prefix=$OPENSHIFT_DATA_DIR --enable-shared make make altinstall export PATH=$OPENSHIFT_DATA_DIR/bin:$PATH export LD_LIBRARY_PATH=$OPENSHIFT_DATA_DIR/lib # Install setuptools cd $OPENSHIFT_TMP_DIR wget --no-check-certificate https://pypi.python.org/packages/2.7/s/setuptools/setuptools-0.6c11-py2.7.egg#md5=fe1f997bc722265116870bc7919059ea sh setuptools-0.6c11-py2.7.egg export PATH=$OPENSHIFT_DATA_DIR/bin:$PATH export LD_LIBRARY_PATH=$OPENSHIFT_DATA_DIR/lib # Install pip cd $OPENSHIFT_TMP_DIR wget --no-check-certificate http://pypi.python.org/packages/source/p/pip/pip-1.1.tar.gz tar zxf pip-1.1.tar.gz cd pip-1.1 python2.7 setup.py install --prefix=$OPENSHIFT_DATA_DIR/lib/python2.7/site-packages/ python2.7 setup.py install export PATH=$OPENSHIFT_DATA_DIR/bin:$PATH export LD_LIBRARY_PATH=$OPENSHIFT_DATA_DIR/lib # Install numpy $OPENSHIFT_DATA_DIR/bin/pip install numpy # House-cleaning cd $OPENSHIFT_TMP_DIR rm -r Python-2.7.3 rm Python-2.7.3.tar.bz2 rm -r pip-1.1/ rm pip-1.1.tar.gz rm setuptools-0.6c11-py2.7.egg # Install CMake cd $OPENSHIFT_TMP_DIR wget http://www.cmake.org/files/v2.8/cmake-2.8.10.2.tar.gz tar xvf cmake-2.8.10.2.tar.gz cd cmake-2.8.10.2 ./configure --prefix=$OPENSHIFT_DATA_DIR gmake gmake install # Download OPenCV cd $OPENSHIFT_TMP_DIR wget http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.4.3/OpenCV-2.4.3.tar.bz2/download tar xvf OpenCV-2.4.3.tar.bz2 # More House-cleaning rm cmake-2.8.10.2.tar.gz rm OpenCV-2.4.3.tar.bz2 cd OpenCV-2.4.3/ rm -r 3rdparty/ rm -r android rm -r doc rm -r data rm -r ios rm -r samples rm -r apps rm README rm -r ../cmake-2.8.10.2/Tests rm -r ../cmake-2.8.10.2/Testing rm -r ../cmake-2.8.10.2/Example rm -r ../cmake-2.8.10.2/Docs rm -r ../cmake-2.8.10.2/Source
mkdir release cd release $OPENSHIFT_DATA_DIR/bin/cmake cmake ../OpenCV-2.4.3 -D BUILD_NEW_PYTHON_SUPPORT=ON -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=$OPENSHIFT_DATA_DIR -D PYTHON_LIBRARY=$OPENSHIFT_DATA_DIR/lib/libpython2.7.so -D CMAKE_INCLUDE_PATH=$OPENSHIFT_DATA_DIR/include/python2.7 -D PYTHON_INCLUDE_DIR=$OPENSHIFT_DATA_DIR/include/python2.7 -D PYTHON_PACKAGES_PATH=$OPENSHIFT_DATA_DIR/lib/python2.7/site-packages -D PYTHON_EXECUTABLE=$OPENSHIFT_DATA_DIR/bin/python2.7 -D WITH_OPENEXR=OFF -D BUILD_DOCS=OFF -DBUILD_SHARED_LIBS=ON .. make make install
Python 2.7.3 (default, May 28 2013, 07:58:37)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> A = cv2.imread("A.jpg")
>>> print A
None
#include <QApplication>
#include <plotmatrix.h>
#include <qwt_plot.h>
#include <qwt_plot_curve.h>
#include <qwt_plot_grid.h>
#include <qwt_symbol.h>
#include <qwt_legend.h>
#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;
class MainWindow: public PlotMatrix
{
public:
MainWindow():PlotMatrix( 2, 3 )
{
for ( int row = 0; row < numRows(); row++ )
{
for ( int col = 0; col < numColumns(); col++ )
{
//set default scale if any.
setAxisScale( QwtPlot::yLeft, row, col, 0, 100 );
setAxisScale( QwtPlot::xBottom, row, col, 0, 255 );
QwtPlot *plt = plot( row, col );
plt->setCanvasBackground( QColor( Qt::darkGray ) );
//Allows the Axis to scale automatically.
plt->setAxisAutoScale(QwtPlot::yLeft, true);
//Show plot grid lines just for aesthetics.
QwtPlotGrid *grid = new QwtPlotGrid();
grid->enableXMin( true );
grid->setMajorPen( Qt::white, 0, Qt::DashLine);
grid->setMinorPen( Qt::gray, 0 , Qt::DotLine );
grid->attach( plt );
}
}
}
};
void getPoints(MatND& hist, int* histSize, QPolygonF& points)
{
points.clear();
for( int h = 0; h < histSize[0]; ++h) {
float bin_value = hist.at<float>(h);
points << QPointF((float)h, bin_value);
}
}
class Curve: public QwtPlotCurve
{
public:
Curve( const QString &title, const QColor &colour, int penSize,
QPolygonF &points ):QwtPlotCurve( title )
{
QColor c = colour;
c.setAlpha( 150 );//handle colour transparency
setPen(c, penSize);
setBrush( c );
setSamples( points );
setRenderHint( QwtPlotItem::RenderAntialiased );
}
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
if (argc < 2)
return 1;
//Read input image
Mat img = imread(argv[1]);
//Convert to grayscale
if (img.data && img.channels() != 3)
return 1;
MainWindow mainWindow;
mainWindow.resize( 600, 400 );
int histSize[] = {256}; // number of bins
float hranges[] = {0.0, 255.0}; // min and max pixel value
const float* ranges[] = {hranges};
int channels[] = {0}; // only 1 channel used
std::vector<Mat> rgbChannels(3);
split(img, rgbChannels);
MatND hist;
QPolygonF points;
calcHist(&rgbChannels[2], 1, channels, Mat(), hist, 1, histSize,ranges);
/*Insert the points that should be plotted on the graph in a
Vector of QPoints or a QPolgonF */
getPoints(hist, histSize, points);
Curve *curve = new Curve("Red Channel", Qt::red, 2, points);
curve->attach( mainWindow.plot(0,0) ); // Attach curve to the plot
calcHist(&rgbChannels[1], 1, channels, Mat(), hist, 1, histSize,ranges);
getPoints(hist, histSize, points);
curve = new Curve("Green Channel", Qt::green, 2, points);
curve->attach( mainWindow.plot(0,1) );
calcHist(&rgbChannels[0], 1, channels, Mat(), hist, 1, histSize,ranges);
getPoints(hist, histSize, points);
curve = new Curve("Blue Channel", Qt::blue, 2, points);
curve->attach( mainWindow.plot(0,2) );
mainWindow.show(); //Show plot
return a.exec();
}
//PlotMatrix.h
#ifndef _PLOT_MATRIX_H_
#define _PLOT_MATRIX_H_
#include <qframe.h>
#include <qwt_plot.h>
class PlotMatrix: public QFrame
{
Q_OBJECT
public:
PlotMatrix( int rows, int columns, QWidget * parent = NULL );
virtual ~PlotMatrix();
int numRows() const;
int numColumns() const;
QwtPlot* plot( int row, int column );
const QwtPlot* plot( int row, int column ) const;
void setAxisScale(int axisId, int row, int col,
double min, double max, double step = 0 );
private:
QVector<QwtPlot *> plotWidgets;
};
#endif
//PlotMatrix.cpp
//This is based on the PlotMatrix implementation in the Qwt Samples.
#include <qlayout.h>
#include <qpen.h>
#include <qwt_plot.h>
#include <qwt_scale_widget.h>
#include <qwt_scale_draw.h>
#include "plotmatrix.h"
PlotMatrix::PlotMatrix( int numRows, int numColumns, QWidget *parent ):
QFrame( parent )
{
plotWidgets.resize( numRows * numColumns );
QGridLayout *layout = new QGridLayout( this );
for ( int row = 0; row < numRows; row++ )
{
for ( int col = 0; col < numColumns; col++ )
{
QwtPlot *plot = new QwtPlot( this );
layout->addWidget( plot, row, col );
plotWidgets[row * numColumns + col] = plot;
}
}
}
PlotMatrix::~PlotMatrix()
{
foreach(QwtPlot* p, plotWidgets)
delete p;
}
int PlotMatrix::numRows() const
{
const QGridLayout *l = qobject_cast<const QGridLayout *>( layout() );
if ( l )
return l->rowCount();
return 0;
}
int PlotMatrix::numColumns() const
{
const QGridLayout *l = qobject_cast<const QGridLayout *>( layout() );
if ( l )
return l->columnCount();
return 0;
}
QwtPlot* PlotMatrix::plot( int row, int column )
{
const int index = row * numColumns() + column;
if ( index < plotWidgets.size() )
return plotWidgets[index];
return NULL;
}
const QwtPlot* PlotMatrix::plot( int row, int column ) const
{
const int index = row * numColumns() + column;
if ( index <plotWidgets.size() )
return plotWidgets[index];
return NULL;
}
void PlotMatrix::setAxisScale( int axis, int row, int col,
double min, double max, double step )
{
QwtPlot *plt = plot( row, col );
if ( plt )
{
plt->setAxisScale( axis, min, max, step );
plt->updateAxes();
}
}
#include <QApplication>
#include <qwt_plot.h>
#include <qwt_plot_curve.h>
#include <qwt_plot_grid.h>
#include <qwt_symbol.h>
#include <qwt_legend.h>
#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;
void getPoints(MatND& hist, int* histSize, QPolygonF& points)
{
for( int h = 0; h < histSize[0]; ++h) {
float bin_value = hist.at<float>(h);
points << QPointF((float)h, bin_value);
}
}
class Curve: public QwtPlotCurve
{
public:
Curve( const QString &title ):
QwtPlotCurve( title )
{
setRenderHint( QwtPlotItem::RenderAntialiased );
}
void setColour(const QColor &color, int penSize)
{
QColor c = color;
c.setAlpha( 150 );
setPen(c, penSize);
setBrush( c );
}
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
if (argc < 2)
return 1;
//Read input image
Mat img = cv::imread(argv[1]);
//Convert to grayscale
if (img.data && img.channels() != 3)
return 1;
QwtPlot plot; //Create plot widget
plot.setTitle( "Plot Demo" ); //Name the plot
plot.setCanvasBackground(Qt::white ); //Set the Background colour
plot.setAxisScale(QwtPlot::xBottom,0,255); //Scale the x-axis
plot.insertLegend(new QwtLegend()); //Insert a legend
int histSize[] = {256}; // number of bins
float hranges[] = {0.0, 255.0}; // min and max pixel value
const float* ranges[] = {hranges};
int channels[] = {0}; // only 1 channel used
std::vector<cv::Mat> rgbChannels(3);
split(img, rgbChannels);
MatND hist;
QPolygonF points;
calcHist(&rgbChannels[2], 1, channels, cv::Mat(), hist, 1, histSize,ranges);
Curve *curve = new Curve("Red Channel");
curve->setColour(Qt::red , 2);//Set colour and thickness for drawn curve.
/*Insert the points that should be plotted on the graph in a
Vector of QPoints or a QPolgonF */
getPoints(hist, histSize, points);
curve->setZ( curve->z() - 1 );
curve->setSamples(points); //pass points to be drawn on the curve
curve->attach( &plot ); // Attach curve to the plot
calcHist(&rgbChannels[1], 1, channels, cv::Mat(), hist, 1, histSize,ranges);
curve = new Curve("Green Channel");
curve->setColour(Qt::green , 2);
points.clear();
getPoints(hist, histSize, points);
curve->setZ( curve->z() - 2 );
curve->setSamples( points );
curve->attach( &plot );
calcHist(&rgbChannels[0], 1, channels, cv::Mat(), hist, 1, histSize,ranges);
curve = new Curve("Blue Channel");
curve->setColour(Qt::blue, 2);
points.clear();
getPoints(hist, histSize, points);
curve->setZ( curve->z() - 3 );
curve->setSamples( points );
curve->attach( &plot );
plot.resize( 600, 400 ); //Resize the plot
plot.show(); //Show plot
return a.exec();
}
function [A, T] = EntropyThresholding(img)
[h, ~] = imhist(img);
h = h/sum(h); % Normalize the histogram so that it sums to 1.
entropies = zeros(256, 1); % Intialize array for storing entropies.
for t = 1:254
White = h(1:t);
Black = h(t+1:255);
% Add 0.001 to prevent division by zero(nan) and log of zero(-inf).
HB = sum((Black/(0.001+sum(Black))).*log((Black+0.001)/(0.001 +sum(Black))));
HW = sum((White/(0.001+sum(White))).*log((White+0.001)/(0.001 +sum(White))));
entropies(t) = HB+HW;
end
[~, T] = max(abs(entropies)); % The Maximal entropy determines the threshold.
T = T - 1;
A = img > T;
#include <QApplication>
#include <qwt_plot.h>
#include <qwt_plot_curve.h>
#include <qwt_plot_grid.h>
#include <qwt_symbol.h>
#include <qwt_legend.h>
#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
if (argc < 2)
return 1;
//Read input image
cv::Mat img = cv::imread(argv[1]);
//Convert to grayscale
if (img.data && img.channels() == 3)
cv::cvtColor(img, img, CV_BGR2GRAY);
else
return 1;
int histSize[1] = {256}; // number of bins
float hranges[2] = {0.0, 255.0}; // min and max pixel value
const float* ranges[1] = {hranges};
int channels[1] = {0}; // only 1 channel used
cv::MatND hist;
// Compute histogram
cv::calcHist(&img, 1, channels, cv::Mat(), hist, 1, histSize,ranges);
double minVal, maxVal;
cv::minMaxLoc(hist, &minVal, &maxVal);//Locate max and min values
QwtPlot plot; //Create plot widget
plot.setTitle( "Plot Demo" ); //Name the plot
plot.setCanvasBackground( Qt::black ); //Set the Background colour
plot.setAxisScale( QwtPlot::yLeft, minVal, maxVal ); //Scale the y-axis
plot.setAxisScale(QwtPlot::xBottom,0,255); //Scale the x-axis
plot.insertLegend(new QwtLegend()); //Insert a legend
QwtPlotCurve *curve = new QwtPlotCurve(); // Create a curve
curve->setTitle("Count"); //Name the curve
curve->setPen( Qt::white, 2);//Set colour and thickness for drawing the curve
//Use Antialiasing to improve plot render quality
curve->setRenderHint( QwtPlotItem::RenderAntialiased, true );
/*Insert the points that should be plotted on the graph in a
Vector of QPoints or a QPolgonF */
QPolygonF points;
for( int h = 0; h < histSize[0]; ++h) {
float bin_value = hist.at<float>(h);
points << QPointF((float)h, bin_value);
}
curve->setSamples( points ); //pass points to be drawn on the curve
curve->attach( &plot ); // Attach curve to the plot
plot.resize( 600, 400 ); //Resize the plot
plot.show(); //Show plot
return a.exec();
}
$ tar -xjvf qwt-6.1-rc3.tar.bz2 $ cd qwt-6.1-rc3 $ qmake qwt.pro $ make $ make install
CONFIG += qwt INCLUDEPATH +="/usr/local/qwt-6.1.0-rc3/include" LIBS += -L/usr/local/qwt-6.1.0-rc3/lib -lqwt
#include <QApplication>
#include <qwt_plot.h>
#include <qwt_plot_curve.h>
#include <qwt_plot_grid.h>
#include <qwt_symbol.h>
#include <qwt_legend.h>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QwtPlot plot;
plot.setTitle( "Plot Demo" );
plot.setCanvasBackground( Qt::white );
plot.setAxisScale( QwtPlot::yLeft, 0.0, 10.0);
plot.insertLegend( new QwtLegend() );
QwtPlotGrid *grid = new QwtPlotGrid();
grid->attach( &plot );
QwtPlotCurve *curve = new QwtPlotCurve();
curve->setTitle( "Pixel Count" );
curve->setPen( Qt::blue, 4 ),
curve->setRenderHint( QwtPlotItem::RenderAntialiased, true );
QwtSymbol *symbol = new QwtSymbol( QwtSymbol::Ellipse,
QBrush( Qt::yellow ), QPen( Qt::red, 2 ), QSize( 8, 8 ) );
curve->setSymbol( symbol );
QPolygonF points;
points << QPointF( 0.0, 4.4 ) << QPointF( 1.0, 3.0 )
<< QPointF( 2.0, 4.5 ) << QPointF( 3.0, 6.8 )
<< QPointF( 4.0, 7.9 ) << QPointF( 5.0, 7.1 );
curve->setSamples( points );
curve->attach( &plot );
plot.resize( 600, 400 );
plot.show();
return a.exec();
}
#include <iostream>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
using namespace cv;
using namespace std;
int main(int argc, char *argv[])
{
if( argc != 2)
{
cout << " No image file is specified \n ";
return -1;
}
Mat src = imread(argv[1]);
vector<vector<Point> > contours;
vector<Vec4i> hierarchy;
findContours( src.clone(), contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_NONE );
Mat singleLevelHoles = Mat::zeros(src.size(), src.type());
Mat multipleLevelHoles = Mat::zeros(src.size(), src.type());
for(vector<Vec4i>::size_type idx=0; idx<hierarchy.size(); ++idx)
{
if(hierarchy[idx][3] != -1)
drawContours(singleLevelHoles, contours, idx, Scalar::all(255), CV_FILLED, 8, hierarchy);
}
bitwise_not(src, src);
bitwise_and(src, singleLevelHoles, multipleLevelHoles);
//Inverse source image.
imwrite("/home/stephen/Pictures/Result0.jpg", src);
//Holes before the bitwise AND operation.
imwrite("/home/stephen/Pictures/Result1.jpg", singleLevelHoles);
//Holes after the bitwise AND Operation.
imwrite("/home/stephen/Pictures/Result2.jpg", multipleLevelHoles);
return 0;
}
main.cpp
|
This contains the main function
which is the starting point of all C++ applications. It is the
main function the loads the main window for the GUI application.
|
mainwindow.cpp
|
This is the source file that
contains the MainWindow class implementation.
|
mainwindow.h
|
This contains the class declaration for the MainWindow class. |
mainwindow.ui
|
This is the UI designer file that could be used to tweak the GUI.
|
| <projectName>.pro | This contains settings that are used for the project compilation. |
Background-color: #000;
#ifndef PLAYER_H
#define PLAYER_H
#include <QMutex>
#include <QThread>
#include <QImage>
#include <QWaitCondition>
#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;
class Player : public QThread
{ Q_OBJECT
private:
bool stop;
QMutex mutex;
QWaitCondition condition;
Mat frame;
int frameRate;
VideoCapture capture;
Mat RGBframe;
QImage img;
signals:
//Signal to output frame to be displayed
void processedImage(const QImage &image);
protected:
void run();
void msleep(int ms);
public:
//Constructor
Player(QObject *parent = 0);
//Destructor
~Player();
//Load a video from memory
bool loadVideo(string filename);
//Play the video
void Play();
//Stop the video
void Stop();
//check if the player has been stopped
bool isStopped() const;
};
#endif // VIDEOPLAYER_H
Player::Player(QObject *parent)
: QThread(parent)
{
stop = true;
}
bool Player::loadVideo(string filename) {
capture.open(filename);
if (capture.isOpened())
{
frameRate = (int) capture.get(CV_CAP_PROP_FPS);
return true;
}
else
return false;
}
void Player::Play()
{
if (!isRunning()) {
if (isStopped()){
stop = false;
}
start(LowPriority);
}
}
void Player::run()
{
int delay = (1000/frameRate);
while(!stop){
if (!capture.read(frame))
{
stop = true;
}
if (frame.channels()== 3){
cv::cvtColor(frame, RGBframe, CV_BGR2RGB);
img = QImage((const unsigned char*)(RGBframe.data),
RGBframe.cols,RGBframe.rows,QImage::Format_RGB888);
}
else
{
img = QImage((const unsigned char*)(frame.data),
frame.cols,frame.rows,QImage::Format_Indexed8);
}
emit processedImage(img);
this->msleep(delay);
}
}
Player::~Player()
{
mutex.lock();
stop = true;
capture.release();
condition.wakeOne();
mutex.unlock();
wait();
}
void Player::Stop()
{
stop = true;
}
void Player::msleep(int ms){
struct timespec ts = { ms / 1000, (ms % 1000) * 1000 * 1000 };
nanosleep(&ts, NULL);
}
bool Player::isStopped() const{
return this->stop;
}
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QFileDialog>
#include <QMessageBox>
#include <player.h>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private slots:
//Display video frame in player UI
void updatePlayerUI(QImage img);
//Slot for the load video push button.
void on_pushButton_clicked();
// Slot for the play push button.
void on_pushButton_2_clicked();
private:
Ui::MainWindow *ui;
Player* myPlayer;
};
#endif // MAINWINDOW_H
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
myPlayer = new Player();
QObject::connect(myPlayer, SIGNAL(processedImage(QImage)),
this, SLOT(updatePlayerUI(QImage)));
ui->setupUi(this);
}
void MainWindow::updatePlayerUI(QImage img)
{
if (!img.isNull())
{
ui->label->setAlignment(Qt::AlignCenter);
ui->label->setPixmap(QPixmap::fromImage(img).scaled(ui->label->size()
Qt::KeepAspectRatio, Qt::FastTransformation));
}
}
MainWindow::~MainWindow()
{
delete myPlayer;
delete ui;
}
void MainWindow::on_pushButton_clicked()
{
QString filename = QFileDialog::getOpenFileName(this,
tr("Open Video"), ".",
tr("Video Files (*.avi *.mpg *.mp4)"));
if (!filename.isEmpty()){
if (!myPlayer->loadVideo(filename.toAscii().data()))
{
QMessageBox msgBox;
msgBox.setText("The selected video could not be opened!");
msgBox.exec();
}
}
}
void MainWindow::on_pushButton_2_clicked()
{
if (myPlayer->isStopped())
{
myPlayer->Play();
ui->pushButton_2->setText(tr("Stop"));
}else
{
myPlayer->Stop();
ui->pushButton_2->setText(tr("Play"));
}
}
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow* w = new MainWindow();
w->setAttribute(Qt::WA_DeleteOnClose, true);
w->show();
return a.exec();
}
#Change this to your include directory. INCLUDEPATH += "/usr/local/include/opencv2" LIBS += `pkg-config --cflags --libs opencv`If you don't have Pkg-config installed replace the last line with the following and replace “/usr/local/lib” with the location of the openCV libraries on your PC.
# Confirm the location of you opencv libraries and change appropriately. LIBS += usr/local/lib \ -lopencv_core \ -lopencv_highgui \ -lopencv_imgproc \ -lopencv_flann \ -lopencv_legacy \ -lopencv_ml \ -lopencv_features2d \ -lopencv_calib3dNow go to 'main.cpp' file and type in the following lines of code and press Ctrl+R to run it.
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
int main(void)
{
// Load an image from the disk and store in variable.
cv::Mat image1 = cv::imread("/home/stephen/Pictures/download.jpg");
// Create a image display window called Figure1.
cv::namedWindow("Figure1");
// Display image in Figure1.
cv::imshow("Figure1", image1);
// Wait until user closes the window or presses Esc Key.
cv::waitKey(0);
return 0;
}
The result should be an empty console window called "qtcreator_process_sub” and a window called “Figure1” containing the loaded image.
Please let me know if this was helpful and if there is tutorial you would like me to write mention it in the comments. Happy Coding!