The Code Junction

** Credits goes to original author of this code

test.php

[sourcecode language="php"]
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST" && !empty($_FILES["userfile"])) {
move_uploaded_file($_FILES["userfile"]["tmp_name"], "tmp/" . $_FILES["userfile"]["name"]);
}
?>
<html>
<head>
<title>File Upload Progress Bar</title>
<style type="text/css">
#bar_blank {
border: solid 1px #000;
height: 20px;
width: 300px;
}

#bar_color {
background-color: #006666;
height: 20px;
width: 0px;
}

#bar_blank, #hidden_iframe {
display: none;
}
</style>
</head>
<body>
<div id="bar_blank">
<div id="bar_color"></div>
</div>
<div id="status"></div>
<form action="<?php echo $_SERVER["PHP_SELF"]; ?>" method="POST"
id="myForm" enctype="multipart/form-data" target="hidden_iframe">
<input type="hidden" value="myForm"
name="<?php echo ini_get("session.upload_progress.name"); ?>">
<input type="file" name="userfile"><br>
<input type="submit" value="Start Upload">
</form>

<script type="text/javascript">
function toggleBarVisibility() {
var e = document.getElementById("bar_blank");
e.style.display = (e.style.display == "block") ? "none" : "block";
}

function createRequestObject() {
var http;
if (navigator.appName == "Microsoft Internet Explorer") {
http = new ActiveXObject("Microsoft.XMLHTTP");
}
else {
http = new XMLHttpRequest();
}
return http;
}

function sendRequest() {
var http = createRequestObject();
http.open("GET", "progress.php");
http.onreadystatechange = function () { handleResponse(http); };
http.send(null);
}

function handleResponse(http) {
var response;
if (http.readyState == 4) {
response = http.responseText;
document.getElementById("bar_color").style.width = response + "%";
document.getElementById("status").innerHTML = response + "%";

if (response < 100) {
setTimeout("sendRequest()", 1000);
}
else {
toggleBarVisibility();
document.getElementById("status").innerHTML = "Done.";
}
}
}

function startUpload() {
toggleBarVisibility();
setTimeout("sendRequest()", 1000);
}

(function () {
document.getElementById("myForm").onsubmit = startUpload;
})();
</script>
</body>
</html>
[/sourcecode]

progress.php

[sourcecode language="php"]
<?php
session_start();

$key = ini_get("session.upload_progress.prefix") . "myForm";
if (!empty($_SESSION[$key])) {
$current = $_SESSION[$key]["bytes_processed"];
$total = $_SESSION[$key]["content_length"];
echo $current < $total ? ceil($current / $total * 100) : 100;
}
else {
echo 100;
}
[/sourcecode]

Today let's see how to create an effective socket program with client and server communication capability. This program is based on TCP protocol. First, server program should be launched. You can specify a port in server for listening client requests. When the server get a client request, server needs to create a separate process for that client. When running client program, client should know IP address and the server port.

Server.c

[sourcecode language="c"]
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/in.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <stdbool.h>
#include <math.h>

float stof(const char* s);
float calculator(char *calculation);

extern int errno;

int main(int argc,char **argv)
{
int clientaddrlen, listenfd, connectfd, bytes_rcvd, listen_queue_size=1;
short int port_no;
char readBuff[1000];
struct sockaddr_in servaddr, clientaddr;
pid_t childpid;
int status;
char sendBuff[1025];

if(argc!=3){
printf("Usage Format: ./server -p <PortNumber>\n");
printf("Sample Run: ./server -p 2000\n");
exit(1);
}
port_no = atoi(argv[argc-1]);
printf("Server running at port #%d\n", port_no);

// Create server socket.
if ( (listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){
fprintf(stderr, "Cannot create server socket! errno %i: %s\n",errno,strerror(errno));
exit(1);
}
printf("Server socket created\n");
// Bind (attach) this process to the server socket.
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(port_no);
errno = bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr));
if(errno < 0){
printf("Server bind failure errno %i: %s\n",errno,strerror(errno));
exit(1);
}
printf("Server socket is bound to port #%d\n", port_no);
// Turn 'listenfd' to a listening socket. Listen queue size is 1.
errno=listen(listenfd,listen_queue_size);
if(errno < 0){
printf("Server listen failure errno %i: %s\n",errno,strerror(errno));
exit(1);
}
printf("Server listening with a queue of size %d. \n", listen_queue_size);
// Wait for connection(s) from client(s).
while (1){
clientaddrlen = sizeof(clientaddr);
connectfd = accept(listenfd, (struct sockaddr *) &clientaddr, &clientaddrlen);
if(connectfd<0){
printf("Server accept failure errno %d: %s\n",errno,strerror(errno));
exit(1);
}
printf("A connection received from a client. Creating a child to serve the client.\n");
if((childpid = fork()) == 0) { /* child process */
close(listenfd); /* close listening socket */
printf("Child process serving the client.\n");
if (recv(connectfd, readBuff, sizeof(readBuff), 0 ) > 0){
printf("Received message: %s\n", readBuff);
float answer = calculator(readBuff);
char msg[60];
char chAns[30]="";
sprintf(chAns,"%f",answer);
strcat(msg,chAns);
write(connectfd,msg, strlen(readBuff));
}
//close(connectfd); /* parent closes connected socket */
exit(1);
}
else if (childpid <0){ /* failed to fork */
printf("Failed to fork\n");
printf("Fork error errno %d: %s\n",errno,strerror(errno));
}
else if(childpid != 0){ /* parent process */
close(connectfd); /* parent closes connected socket */
childpid = wait(&status);
}
}
return 0;
}

float calculator(char calculation[256])
{

char *token;

char *val1;
char *val2;

float v1;
float v2;
float ans=-9999.0f;

bool validCal = true;

printf("****\n");

char tempCalculation[256];

strcpy(tempCalculation,calculation);

printf("****\n");

token = strtok(tempCalculation,"+-*//^");

int c = 0;
while(token != NULL)
{
c++;
printf("%d\n",c);

if(c == 1)
val1 = token;

if(c == 2)
val2 = token;

printf("%s\n",token);
token = strtok(NULL,"+-*//^");

}

if(c == 2)
{

int i1;
const int lenVal1 = strlen(val1);
for(i1=0; i1<lenVal1 ; i1++)
{
if(!isdigit(val1[i1]))
break;
}
if(i1 != lenVal1)
validCal = false;

int i2;
const int lenVal2 = strlen(val2)-1;
for(i2=0; i2<lenVal2 ; i2++)
{
if(!isdigit(val2[i2]))
break;
}
if(i2 != lenVal2)
validCal = false;

printf("operand1:%soperand2:%s\nlen1:%dlen2%d\n",val1,val2,lenVal1,lenVal2);

if(validCal)
{
char operator = calculation[lenVal1];

printf("Operator%c\n",operator);
printf("Calculation:%s\n",calculation);

v1 = stof(val1);
v2 = stof(val2);

printf("v1=%f\n",v1);
printf("v2=%f\n",v2);

float fv1 = stof(val1);
printf("fv1=%f\n",fv1);

//float f1 = 56.4f;
//float f2 = 2.4f;

if(operator == '+')
{
printf("Addition\n");
ans = v1 + v2;
}
else if(operator == '-')
{
printf("Substraction\n");
ans = v1 - v2;
}
else if(operator == '*')
{
printf("Multiplication\n");
ans = v1 * v2;
}
else if(operator == '/')
{
printf("Devision\n");
ans = v1 / v2;
}
else if(operator == '^')
{
printf("Power\n");

}

else
{

}

printf("Answer:%f\n",ans);

}
else
{
printf("The values are not numeric!\n");

}

return ans;

}
else
{
printf("Two operands are required for calculation\n");
validCal = false;

return ans;

}

};

float stof(const char* s){
float rez = 0, fact = 1;
if (*s == '-'){
s++;
fact = -1;
};

int point_seen;
for (point_seen = 0; *s; s++){
if (*s == '.'){
point_seen = 1;
continue;
};
int d = *s - '0';
if (d >= 0 && d <= 9){
if (point_seen) fact /= 10.0f;
rez = rez * 10.0f + (float)d;
};
};
return rez * fact;
};

[/sourcecode]

Client.c

[sourcecode language="c"]
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/in.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
int main(int argc,char **argv)
{
int clientfd;
short int port_no;
char msg[1000];
char buff[1000];

struct sockaddr_in servaddr;
char *server_ip_address;
if(argc!=5){
printf("Usage Format: ./client -a <IPAddress> -p <PortNumber>\n");
printf("Sample Run: ./client -a 127.0.0.1 -p 2000\n");
exit(1);
}
server_ip_address=(char *)argv[2];
port_no = atoi(argv[4]);
printf("Client will connect to the server at IP %s, port #%d\n", server_ip_address, port_no);

// Create client socket.
if((clientfd = socket(AF_INET, SOCK_STREAM, 0))<0){
printf("Socket could not be created\n");
printf("errno %i: %s\n",errno,strerror(errno));
exit(1);
}
printf("Client socket created\n");
errno=0;
// Connect to the server client
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(port_no);
if((inet_pton(AF_INET, server_ip_address, &servaddr.sin_addr))<=0){
printf("inet_pton error for %s\n",server_ip_address);
printf("errno %d: %s\n",errno,strerror(errno));
exit(1);
}
errno=0;
if((connect(clientfd, (struct sockaddr *) &servaddr, sizeof(servaddr)))<0){
printf("Connect error\n");
printf("errno %d: %s\n",errno,strerror(errno));
exit(1);
}
printf("Client socket connected\n");
// Read one line of message from the input and send it to the server.
while(1)
{
printf("\nEnter the message to be sent to the server: ");
scanf("%s", msg);
send(clientfd, msg, strlen(msg)+1, 0);
//close(clientfd);

if (recv(clientfd, buff, sizeof(buff), 0 ) > 0){
printf("Server Response: %s\n", buff);

}
}
return 0;
}

[/sourcecode]

Run server :

gcc -oa server.c

./a -p 2000

Run client:

gcc -ob client.c

./b -a 127.0.0.1 -p 2000

Demo

[sourcecode language="javascript"]

<script src="http://openlayers.org/api/OpenLayers.js"></script>

<script type="text/javascript">
function init(){
map = new OpenLayers.Map('map');
base_layer = new OpenLayers.Layer.WMS( "OpenLayers WMS",
"http://labs.metacarta.com/wms/vmap0", {layers: 'basic'} );
map.addLayer(base_layer);
map.setCenter(new OpenLayers.LonLat(79.8333,6.9167),7);

var markers = new OpenLayers.Layer.Markers( "Markers" );
map.addLayer(markers);

var size = new OpenLayers.Size(21,25);
var offset = new OpenLayers.Pixel(-(size.w/2), -size.h);
var icon = new OpenLayers.Icon('http://www.openlayers.org/dev/img/marker.png', size, offset);
markers.addMarker(new OpenLayers.Marker(new OpenLayers.LonLat(79.8333,6.9167),icon));
markers.addMarker(new OpenLayers.Marker(new OpenLayers.LonLat(79.8333,6.9167),icon.clone()));
marker = new OpenLayers.Marker(new OpenLayers.LonLat(79.8333,6.9167));
markers.addMarker(marker);

marker.events.register("click", marker, function(e){
popup = new OpenLayers.Popup.FramedCloud("chicken",
new OpenLayers.LonLat(79.8333,6.9167),
new OpenLayers.Size(200, 200),
"I was here <br><img src='uploads/me.png' width='90' height='90'>",
null, true);
map.addPopup(popup);
});
}

</script>

</head>

<body onLoad="init()">

<div id="map" style="width:500px;height:300px;margin-left: auto;margin-right:auto;"></div>

[/sourcecode]

Demo

[sourcecode language="javascript"]
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Getting the coordinates of a click in OpenLayers Map</title>
<script src="http://openlayers.org/api/OpenLayers.js"></script>

<script type="text/javascript">
function init(){
map = new OpenLayers.Map('map');
base_layer = new OpenLayers.Layer.WMS( "OpenLayers WMS",
"http://labs.metacarta.com/wms/vmap0", {layers: 'basic'} );
map.addLayer(base_layer);
map.setCenter(new OpenLayers.LonLat(79.8333,6.9167),7);

map.events.register('click', map, handleMapClick);
}

function handleMapClick(evt)
{
var lonlat = map.getLonLatFromViewPortPx(evt.xy);
alert("latitude : " + lonlat.lat + ", longitude : " + latitude);

}
</script>

</head>
<body onLoad="init()">
</body>
</html>

[/sourcecode]

1. Erosion

[caption id="attachment_796" align="alignnone" width="408"]

Erosion[/caption]

generally decreases the sizes of objects and removes small anomalies by subtracting objects with a radius smaller than the structuring element.

void cvErode( const CvArr* src, CvArr* dst,
IplConvKernel*element=NULL, int iterations=1 );

The function describes:
src
-Source image
dst
-Destination image
element
-Structuring element used for erosion. If it is NULL, a 3×3 rectangular
structuring element is used
iterations
-Number of times erosion is applied

[sourcecode language="c"]
#include "stdafx.h"
#include <cv.h>
#include <cxcore.h>
#include <highgui.h>

int _tmain(int argc, _TCHAR* argv[])
{

IplImage *img = cvLoadImage("Image2.png");
IplImage *dest =cvCreateImage(cvSize(img->width,img->height),8,3);
IplImage *temp =cvCreateImage(cvSize(img->width,img->height),8,3);

cvErode(img,dest,NULL,2);

cvNamedWindow("Image:");
cvNamedWindow("Destination:");

cvShowImage("Image:", img);
cvShowImage("Destination:", dest);

cvWaitKey(0);

cvDestroyWindow("Image:");
cvDestroyWindow("Destination:");

cvReleaseImage(&img);
cvReleaseImage(&dest);
return 0;
}

[/sourcecode]

2. Dilation

[caption id="attachment_798" align="alignnone" width="404"]

Dilation[/caption]

generally increases the sizes of objects, filling in holes and broken areas, and connecting areas that are separated by spaces smaller than the size of the structuring element.

void cvDilate( const CvArr* src, CvArr* dst, IplConvKernel*
element=NULL, int iterations=1 );

[sourcecode language="c"]
#include "stdafx.h"
#include <cv.h>
#include <cxcore.h>
#include <highgui.h>

int _tmain(int argc, _TCHAR* argv[])
{

IplImage *img = cvLoadImage("Image2.png");
IplImage *dest =cvCreateImage(cvSize(img->width,img->height),8,3);
IplImage *temp =cvCreateImage(cvSize(img->width,img->height),8,3);

cvDilate(img,dest,NULL,2);

cvNamedWindow("Image:");
cvNamedWindow("Destination:");

cvShowImage("Image:", img);
cvShowImage("Destination:", dest);

cvWaitKey(0);

cvDestroyWindow("Image:");
cvDestroyWindow("Destination:");

cvReleaseImage(&img);
cvReleaseImage(&dest);
return 0;
}

[/sourcecode]


3. MorphologyEx 

This function performs advanced morphological transformations, which enables composite operations such as Opening, Closing, Morphological Gradient, Top Hat and Black Hat. The one function that lets you do all this is:
void cvMorphologyEx( const CvArr* src, CvArr* dst, CvArr* temp,
IplConvKernel* element, int operation, int iterations=1 );

The function describes:
src
-Source image
dst
-Destination image
temp
-Temporary image, required in some cases
element
-Structuring element
operation
-Type of morphological operation, one of:
CV_MOP_OPEN - opening
CV_MOP_CLOSE - closing
CV_MOP_GRADIENT - morphological gradient
CV_MOP_TOPHAT - "top hat"
CV_MOP_BLACKHAT - "black hat"
iterations
-Number of times erosion and dilation are applied

[sourcecode language="c"]
#include "stdafx.h"
#include <cv.h>
#include <cxcore.h>
#include <highgui.h>

int _tmain(int argc, _TCHAR* argv[])
{

IplImage *img = cvLoadImage("Image2.png");
IplImage *dest =cvCreateImage(cvSize(img->width,img->height),8,3);
IplImage *temp =cvCreateImage(cvSize(img->width,img->height),8,3);

cvMorphologyEx(img,dest,temp,structure,MOP_CLOSE,1);
cvNamedWindow("Image:");
cvNamedWindow("Destination:");

cvShowImage("Image:", img);
cvShowImage("Destination:", dest);

cvWaitKey(0);

cvDestroyWindow("Image:");
cvDestroyWindow("Destination:");

cvReleaseImage(&img);
cvReleaseImage(&dest);
return 0;
}
[/sourcecode]

Edge detection is considered as the most common approach for detecting meaningful discontinuities in the grey- level.

1. Sobel Operator

void cvSobel( const CvArr* src, CvArr* dst, int xorder, int yorder,
int aperture_size=3 );

Parameters:
src – Source image
dst – Destination image
xorder – First Order derivative in x direction
yorder – First Order derivative in y direction
apertureSize – Size of the extended Sobel kernel, must be 1, 3, 5 or 7

The function is called with (xorder=1, yorder=0, aperture_size=3)
|-1 0 1|
|-2 0 2|
|-1 0 1|

and (xorder=0, yorder=1, aperture_size=3)

|-1 -2 -1|
| 0 0 0|
| 1 2 1|

[sourcecode language="c"]
#include <cv.h>
#include <cxcore.h>
#include <highgui.h>

int _tmain(int argc, _TCHAR* argv[])
{

IplImage *img = cvLoadImage("building.jpg");

IplImage *gray;
IplImage *sobelX;
IplImage *sobelY;
IplImage *tempX;
IplImage *tempY;

gray =cvCreateImage(cvSize(img->width,img->height),8,1);

cvCvtColor(img,gray,CV_RGB2GRAY);
if(!img)
{
printf("Error :coudn't open the image file.\n");
return 1;
}

sobelX =cvCreateImage(cvSize(img->width,img->height),8,1);
sobelY =cvCreateImage(cvSize(img->width,img->height),8,1);

// Create Temp Images
tempX =cvCreateImage(cvSize(img->width,img->height),IPL_DEPTH_16S,1);
tempY =cvCreateImage(cvSize(img->width,img->height),IPL_DEPTH_16S,1);

cvSobel(gray,tempX,1,0,3);
cvSobel(gray,tempY,0,1,3);

// Convert to the Absolute Value
cvConvertScaleAbs(tempX,sobelX,1,0);
cvConvertScaleAbs(tempY,sobelY,1,0);

cvNamedWindow("Image:",1);
cvShowImage("Image:", img);

cvNamedWindow("Image:",1);
cvShowImage("Gray:", gray);

cvNamedWindow("sobelx:",1);
cvNamedWindow("sobely:",1);

cvShowImage("sobelx:", sobelX);
cvShowImage("sobely:", sobelY);

cvWaitKey(0);

cvDestroyWindow("Image:");
cvDestroyWindow("Gray:");
cvDestroyWindow("sobelx:");
cvDestroyWindow("sobely:");

cvReleaseImage(&img);
cvReleaseImage(&gray);
cvReleaseImage(&sobelX);
cvReleaseImage(&sobelY);
return 0;
}

[/sourcecode]

1. LaplacianOperator

The function calculates the Laplacian of the source image by filtering the image with the
following 3X3 aperture:

|-1 -1 -1|
| -1 8 -1|
|-1 -1 -1|

Use the following function to apply the Laplacian operator:

void cvLaplace(const CvArr* src, CvArr* dst, int apertureSize=3)

Parameters:
src – Source image
dst – Destination image
apertureSize – Size of the extended Sobel kernel

[sourcecode language="c"]
#include <cv.h>
#include <cxcore.h>
#include <highgui.h>

int _tmain(int argc, _TCHAR* argv[])
{
IplImage *img = cvLoadImage("building.jpg");

IplImage *gray;
IplImage *laplace;
IplImage *temp;

gray =cvCreateImage(cvSize(img->width,img->height),8,1);
cvCvtColor(img,gray,CV_RGB2GRAY);

temp =cvCreateImage(cvSize(img->width,img->height),IPL_DEPTH_16S,1);
laplace =cvCreateImage(cvSize(img->width,img->height),8,1);

IplImage *dst1=cvCreateImage(cvSize(img->width,img->height),8,1);

cvLaplace(gray,temp,3);
cvConvertScaleAbs(temp,laplace,1,0);

cvSmooth( laplace, dst1,CV_MEDIAN,3,3);

cvNamedWindow("Image:",1);
cvShowImage("Image:", img);

//cvNamedWindow("temp:",1);
cvNamedWindow("Laplace:",1);
cvNamedWindow("remove:",1);

cvShowImage("Laplace:", laplace);
cvShowImage("remove:", dst1);

cvWaitKey(0);

cvDestroyWindow("Image:");
cvDestroyWindow("Laplace:");
cvDestroyWindow("remove:");

//cvReleaseImage(&img);
cvReleaseImage(&laplace);
cvReleaseImage(&dst1);
return 0;
}

[/sourcecode]

The Code Junction

How to use PHP session upload progress bar

Linux Client Server Socket Program

OpenLayers - How to add markers and popups

Getting the coordinates of a click in OpenLayers Map

Image Morphology using OpenCV

Edge Detection with OpenCV

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