eInternals » Web development

Disable right click menu in Flash (swf files)

kiranvj — Sat, 02 Feb 2008 05:23:07 +0000

There are times when you have to disable the default right click menu on flash files on your webpages.

Uza has a suggested a method to completely disable the flash right menu.
Check the article link at his website http://www.uza.lt/blog/2007/08/solved-right-click-in-as3
and the Demo here http://www.uza.lt/rightclick/

You can also download the project files from the Google code
Project website:
http://code.google.com/p/custom-context-menu/

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Change login link to logout link.

kiranvj — Sat, 29 Dec 2007 08:10:00 +0000

There are times when you have to change the login link in your webpage to a logout link when a user successfully logged in.

Here is a simple way to do it in PHP

Suppose your menu is

Link 1
Login
Link 2

the corresponding HTML code will look like

Link 1
Login
Link 2

After successful login most probably you will set a session. Say the name of the session variable is username
Then the code for the menu will look like

Link 1
Logout ");
echo($_SESSION['username']);// displays username
}
else
{
echo("Login ");
}
?>
Link 2

and also make sure to add

on top of your page.

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How to enable or disable Image Toolbar in Internet Explorer

kiranvj — Tue, 25 Dec 2007 07:42:53 +0000

Image Toolbar is a small toolbar shown in Intetnet Explorer above an image when the mouse moves over the image. The purpose of the Image Toolbar is to save the image, print the image, mail the image and to open the My Pictures folder.

Image Toolbar in Internet Explorer

The usual method of saving an image from the Internet explorer is by right clicking the image and selecting Save Picture as…. In some sites the web designers disable the right click the option, so the user cannot right click the image and click Save the Picture….
But in that case also the Image Toolbar will display.

Disabling the Image Toolbar
Add an attribute GALLERYIMG in the img tag

This will disable the Image Toolbar

Enabling the Image Toolbar
In small images the Image Toolbar will not be shown automatically. If we want to show the Image Toolbar in small images we have to enable it.

This will enable the Image Toolbar.

The above mentioned techniques will only disable/enable the Image Toolbar for only the particular image.


Toolbar Enabled	Toolbar disabled

To enable/disable the Toolbar on the entire web page use this code.
Insert inside head tag

Setting GALLERYIMG=”true” in an IMG tag will override this setting, and the Image Toolbar will be show for that image.

Permanently disable the Image Toolbar in Internet Explorer

Either right-click the toolbar when it is displayed and click Disable image toolbar.
Or
Go to the Advanced tab of the Internet Options which is located on the Tools menu within Internet Explorer. Clear the Enable Image Toolbar check box and click OK. After the image toolbar is disabled, no settings can override this and the image toolbar will not be displayed again until the user selects Enable Image Toolbar.

Remarks:
Please not that you can also use the yes instead of true and no instead of false.

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Implementing CAPTCHA using PHP

kiranvj — Tue, 25 Dec 2007 05:41:00 +0000

How to implement a CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) using PHP

Implementing CAPTCHA using PHP

Steps involved in this tutorial:

Create a background image, the more messier the more better.
Load a font file to display the CAPTCHA text
Generate a random unique text
Store the generated text in a Session variable to be used later for validation
Write the CAPTCHA text to the image created in Step 1
Generate the CAPTCHA image
Also created a php page with the CAPTCHA image, a text box for input and a Submit button to show a working model (this step is not explained in detail, its simple PHP code, download and check the source files)

Click here for a working model

The first thing I did was opened Photoshop and created this image to use as a background image

If you don’t have Photoshop don’t worry, any image editor will do. Even M$ Paint is enough. Just create an image with random colors. Save the image in PNG format with filename captcha.png. If you don’t like PNG , save in the format you like and use the appropriate function to load image.

Ok now the background image is ready.

Using the php function imagecreatefrompng load the image we just created using the code

$captchaImage = imagecreatefrompng("captcha.png");

Next using the php function imageloadfont , load a font to display the CAPTCHA text.

The parameter of the imageloadfont function is a font filename. I tried using a TTF font file. But somehow it doesn’t work. The possible reason for this, from php.net (http://au3.php.net/manual/en/function.imageloadfont.php)

“ The font file format is currently binary and architecture dependent. This means you should generate the font files on the same type of CPU as the machine you are running PHP on.”

So I created a GD Font (.gdf) file. You can create a .gdf file from TTF using http://www.wedwick.com/wftopf.exe or http://www.puremango.co.uk/cm_fontmaker_114.php or download some good GDF fonts from http://www.widgnet.com/gdf_fonts/fonts.html
After loading the font the next step is to generate a random, unique string to use as CAPTCHA text. This is how the CAPTCHA text is created

 $captchaText = substr(md5(uniqid('')),-9,9);

Generate a string using uniqid(), MD5 it, extract the last 9 characters using substr()

Now store this generated text in some session variable for later validation. You can also store this generated text in a cookie or database instead of a session variable.

Now write this generated string on the background image we created earlier. For this we use the function imagestring()

Output the image in PNG format using imagepng() . Now you will have an image with a random, unique string written in it.

Another advantage of this code is, to display the CAPTCHA image you only need to include a image tag in your webpage and give the source as capthca.php. Then the CAPTCHA image will be displayed.

Eg :

I have also created a php file to show its working. You can download the full files with some additional GD fonts here.


/***
 * File : captcha.php
 * Description : Creating a captha image and
 * store the text in a session variable
 * Author : Kiran Paul V.J. aka kiranvj aka human
 * License : Freeware
 * Last update : 22-Aug-2007
 */

  // Initialize session data
session_start();
// all images in this file is of PNG format,
// there is not specific reason for that.
// this line is used to set the header of the page
// setting the header to image/png means this page
// contians data of image->PNG type
header("Content-type: image/png");

// create a new image resource from a file
$captchaImage = imagecreatefrompng("captcha.png")
or die("Cannot Initialize new GD image stream");

//Loads a new font from a file
$captchaFont = imageloadfont("anonymous.gdf");

// Create the captcha text with some manipulation
$captchaText = substr(md5(uniqid('')),-9,9);

// stores the captha text in a session variable
$_SESSION['session_captchaText'] = $captchaText;

// Allocating color for captcha text to be used
// in imagestring function
$captchaColor = imagecolorallocate($captchaImage,0,0,0);

// drawing the string 
imagestring($captchaImage,$captchaFont,15,5,$captchaText,$captchaColor);

// Outputs the captha image in PNG format.
// You can change the image format using
// imagejpeg,imagegif ,imagewbmp etc.
imagepng($captchaImage);

//frees memory
imagedestroy($captchaImage);
?>

Download full source

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