PHP font_size Captcha issue - php

I tried to change the $font_size but it seems it is not working. It stays the same no matter what. Even if I altered the $font_size up to 130. It stays the same:
<?php
header('Content-type: image/png');
$rand_num = rand(1000, 9999);
$font_size = 130;
$image_width = 110;
$image_height = 20;
$image = imagecreate($image_width, $image_height);
imagecolorallocate($image, 255, 255, 255);
$black_color = imagecolorallocate($image, 0, 0, 0);
imagestring($image, $font_size, 0, 0, $rand_num, $black_color);
for($x=0; $x <= 30; $x++){
$x1 = rand(1, 100);
$y1 = rand(1, 100);
$x2 = rand(1, 100);
$y2 = rand(1, 100);
imageline($image, $x1, $y1, $x2, $y2, $black_color);
}
imagepng($image);
?>

According to PHP Manual, The font parameter
Can be 1, 2, 3, 4, 5 for built-in fonts in latin2 encoding (where
higher numbers corresponding to larger fonts) or any of your own font
identifiers registered with imageloadfont().
So you have to try 1 2 3 4 5 and not 130.

For built in fonts, font size can be from 1,2,3,4 and 5. Please refer to http://php.net/manual/en/function.imagestring.php

You can change the font size using imagettftext function.
imagettftext($image, $font_size, $angle, $x, $y, $text_color, '$font-family', $text);
$image is the $imagecreate function
$font_size is the size of font you want.
$angle is the angle of the fonts tilted
$x and $y are coordinates.
$text_color is the imagecolorallocate function
$font-family is the family of font you want to use
$text is the text or random text to be displayed

Related

No text shown, only captcha lines are visible

PHP code:
<?php
ob_start();
session_start();
$_SESSION['secure'];
header('content-type:image/png');
$text="hello";
$font_size=25;
$width=200;
$height=200;
$image=imagecreate($width, $height);
imagecolorallocate($image, 255, 255, 255);
$black = imagecolorallocate($image, 0, 0, 0);
for($x=1; $x <= 30; $x++) {
$x1 = rand(1, 100);
$y1 = rand(1, 100);
$x2 = rand(1, 100);
$y2 = rand(1, 100);
imageline($image, $x1, $y1, $x2, $y2, $black);
}
imagettftext($image, $font_size, 0, 15, 30, $black, 'consolas.ttf', $text);
$imgSrc="out.png";
imagejpeg($image, $imgSrc);
?>
When the image is generated, only lines are drawn but text("hello") is not drawn on it.
The font is also in the same directory, I have also kept it in another directory and added the complete path no luck.
I'm debugging this issue and found that font file is not accessible.
I have checked by turning on debugging as below:
error_reporting(E_ALL);
ini_set("display_errors", 1);
And commented lines below.
header('content-type:image/png');
imagepng($image);
Got error:
Warning: imagettftext(): Could not find/open font in
/var/www/html/index.php on line 24
Soultion:
Path to font file should be realpath on server. So the code should be:
imagettftext($image, $font_size, 0, 15, 30, $black, realpath('consolas.ttf'), $text);
Also change in render image without giving $imgSrc and changing it to
imagepng($image);
instead of
$imgSrc="out.png";
imagejpeg($image, $imgSrc);
Finally complete code will look like:
ob_start();
session_start();
$_SESSION['secure'];
header('content-type:image/png');
$text = "hello";
$font_size = 25;
$width = 200;
$height = 200;
$image = imagecreate($width, $height);
imagecolorallocate($image, 255, 255, 255);
$black = imagecolorallocate($image, 0, 0, 0);
for ($x = 1; $x <= 30; $x++) {
$x1 = rand(1, 100);
$y1 = rand(1, 100);
$x2 = rand(1, 100);
$y2 = rand(1, 100);
imageline($image, $x1, $y1, $x2, $y2, $black);
}
imagettftext($image, $font_size, 0, 15, 30, $black, realpath('Consolas.ttf'), $text);
imagepng($image);

Position variable text centered under label using PHP GD

I have successfully outputted text (consisting of 2-3 digit numbers) onto an image using the PHP GD imaging library. Next I would like to position this text and center it under labels included in the image. I have it working now by looking at the image and hardcoding position values, but this is not ideal as the numbers vary and may not be the same length each time the code is run.
Here is a simplified version of what I have so far:
<?php
$font = 'arial.ttf';
$fontsize = 60;
$value1 = $_GET['r'];
$value2 = $_GET['rm'];
$value3 = $_GET['w'];
$image = imagecreatefrompng('image.png');
$fontcolor = imagecolorallocate($image, 255, 255, 255);
$x1 = 80;
$x2 = 160;
$x3 = 280;
$y = 1050;
imagettftext($image, $fontsize, 0, $x1, $y, $fontcolor, $font, $value1);
imagettftext($image, $fontsize, 0, $x2, $y, $fontcolor, $font, $value2);
imagettftext($image, $fontsize, 0, $x3, $y, $fontcolor, $font, $value3);
header('Content-type: image/png');
imagepng($image);
imagedestroy($image);
?>
I believe that I need to use imagettfbbox, but how do I position the box according to the label in the image?
Is it possible to set a primary position for each label (as they will never move) and center according to that no matter the length of the number? For example, if a 4 digit number was entered it would appear in the same place as a 2 digit number centered under its label.
Box sizing was giving me strange results, so I solved this by creating a function that calculates the number of digits in each number and sends a position variable back.
function position($value, $pos) {
$length = strlen((string)$value);
return $pos - (20 * $length);
}
$value1 = $_GET['r'];
$value2 = $_GET['rm'];
$value3 = $_GET['w'];
$x1 = position($value1, 110);
$x2 = position($value2, 310);
$x3 = position($value3, 545);
$y = 1050;
imagettftext($image, $fontsize, 0, $x1, $y, $fontcolor, $font, $value1);
imagettftext($image, $fontsize, 0, $x2, $y, $fontcolor, $font, $value2);
imagettftext($image, $fontsize, 0, $x3, $y, $fontcolor, $font, $value3);

How to account for font swash with PHP and GD

I have the following code to print text on an image. I am also adding a debug box around the text. However, I noticed the text on the left lies outside of the box that PHP gives me with imagettfbbox.
This looks like an issue with the font swash. Is there anyway to account for this? Can I figure out the distance between the start of the swash and the actual position imagettfbbox gives to me?
I don't think this is an issue with the font, as I tried it with a few script style fonts and the results were similar.
<?php
$font = 'scriptin.ttf';
$text = 'Ipsum';
$size = 30;
$image = imagecreatetruecolor(200, 200);
$fontColour = imagecolorallocate($image, hexdec('11'), hexdec('11'), hexdec('11'));
$bgColour = imagecolorallocate($image, hexdec('CC'), hexdec('CC'), hexdec('CC'));
imagefilledrectangle($image, 0, 0, 200, 200, $bgColour);
$dimensions = imagettfbbox($size, 0, $font, $text);
imagefilledrectangle(
$image,
$dimensions[0] + 40,
$dimensions[7] + 50,
$dimensions[2] + 40,
$dimensions[3] + 50,
imagecolorallocate($image, mt_rand(1, 180), mt_rand(1, 180), mt_rand(1, 180))
);
imagettftext(
$image,
$size,
0,
40,
50,
$fontColour,
$font,
$text
);
header('Content-Type: image/png');
imagepng($image);
The code and font is available here: https://github.com/AydinHassan/image-swash-example
If you point a VHOST at the repository, you can just hit swash.php
Edit: This appears to be fixed in PHP 7.0.12 (bug #53504) so the code below shouldn't be required.
Based on a comment in the PHP manual I've written the following function to calculate and return the difference between where GD thinks the left side of the bounding box is and where the leftmost pixel is found:
function xadjust($size, $angle, $fontfile, $text)
{
$bbox = imagettfbbox($size, $angle, $fontfile, $text);
$width = $bbox[4] - $bbox[6]; // upper right x - upper left x;
$height = $bbox[1] - $bbox[7]; // lower left y - upper left y;
// create an image with height and width doubled to fit any 'swash'.
$im = imagecreatetruecolor($width * 2, $height * 2);
// set background color to opaque black.
imagefill($im, 0, 0, 0x00000000);
// draw the text in opaque white.
imagettftext(
$im,
$size,
0,
$width / 2,
$height,
0x00ffffff,
$fontfile,
$text
);
// set the min-width to its possible maximum.
$min_x = $width * 2;
for ($x = 0; $x < $width * 2; $x++) {
// each x-pixel (horizontal)
for ($y = 0; $y < $height * 2; $y++) {
// each y-pixel (vertical)
if (imagecolorat($im, $x, $y) > 0) {
// non-black pixel found!
$min_x = min($x, $min_x);
}
}
}
imagedestroy($im);
// return the difference between where GD thinks the bounding box is and
// where we found the leftmost non-black pixel.
return (($width / 2) - $min_x) - abs($bbox[0]);
}
This can be integrated to your script fairly easily:
$font = 'scriptin.ttf';
$text = 'Ipsum';
$size = 30;
$image = imagecreatetruecolor(200, 200);
$fontColour = imagecolorallocate($image, hexdec('11'), hexdec('11'), hexdec('11'));
$bgColour = imagecolorallocate($image, hexdec('CC'), hexdec('CC'), hexdec('CC'));
imagefilledrectangle($image, 0, 0, 200, 200, $bgColour);
$xadjust = xadjust($size, 0, $font, $text); // 1. get the adjust value.
$dimensions = imagettfbbox($size, 0, $font, $text);
imagefilledrectangle(
$image,
$dimensions[0] + 40 - $xadjust, // 2. move the left-side of the box to the left.
$dimensions[7] + 50,
$dimensions[2] + 40 - $xadjust, // 3. move the right-side of the box to the left.
$dimensions[3] + 50,
imagecolorallocate($image, mt_rand(1, 180), mt_rand(1, 180), mt_rand(1, 180))
);
imagettftext(
$image,
$size,
0,
40,
50,
$fontColour,
$font,
$text
);
header('Content-Type: image/png');
imagepng($image);
This gives me the following output:
I've run it with a few other fonts and sizes and it seems to be accurate to within 1 pixel.

Captcha validation in PHP

I used the following code to create Captcha to my form. Captcha creating well. Now I want to change font-size, and Font character spaces. I don't know how to change in the following code.
<?php
session_start();
$code= substr(str_shuffle("abcdefghijklmnopqrstuvwxyz"), 0, 6);
$_SESSION["code"]=$code;
$im = imagecreatetruecolor(150, 35);
$bg = imagecolorallocate($im, 255, 255, 255);
$fg = imagecolorallocate($im, 0, 0, 0);
imagefill($im, 5, 5, $bg);
imagestring($im, 5, 8, 8, $code, $fg);
header("Cache-Control: no-cache, must-revalidate");
header('Content-type: image/png');
imagepng($im);
imagedestroy($im);
?>
You can use the code below to implement a simple captcha using gd library of PHP. As you are beginner, here is a sample code for quick testing, it covers font-sizing also:
<?php
session_start();
header('Content-type: image/jpeg');
$text = rand(1000, 9999);
$font_size = 30;
$image_width = 200;
$image_height = 40;
$image = imagecreate($image_width, $image_height);
imagecolorallocate($image, 255, 255, 255);
$text_color = imagecolorallocate($image, 0, 0, 0);
for ($x=1; $x<=40; $x++) {
$x1 = rand(1, 100);
$y1 = rand(1, 100);
$x2 = rand(1, 100);
$y2 = rand(1, 100);
imageline($image, $x1, $y1, $x2, $y2, $text_color);
}
imagettftext($image, $font_size, 0, 15, 30, $text_color, 'FREESCPT.ttf', $text);
imagejpeg($image);
?>
In imagettftext function:
imagettftext($image, $font_size, $angle, $x, $y, $text_color, '$font-family', $text);
$image is the $imagecreate function
$font_size is the size of font you want.
$angle is the angle of the fonts tilted
$x and $y are coordinates.
$text_color is the imagecolorallocate function
$font-family is the family of font you want to use
$text is the text or random text to be displayed
Here is the good tutorial on how to build captcha in php -> link
you can change font using imagestring function

PHP GD ttftext center alignment

I'm using imagettftext to make a bar graph and at the top of each bar I want to put the value.
I have the following variables for each bar (which are really rectangles)
$x1
$y1
$x2
$y2
$imagesx
$imagesy
$font_size
Also, The fontsize should decrease as the string length increases.
Do it like this. Remember to place the font file "arial.ttf" in current directory:
<?php
// Create a 650x150 image and create two colors
$im = imagecreatetruecolor(650, 150);
$white = imagecolorallocate($im, 255, 255, 255);
$black = imagecolorallocate($im, 0, 0, 0);
// Set the background to be white
imagefilledrectangle($im, 0, 0, 649, 149, $white);
// Path to our font file
$font = './arial.ttf';
//test it out
for($i=2;$i<10;$i++)
WriteTextForMe($im, $font, str_repeat($i, $i), -140 + ($i*80), 70 + rand(-30, 30), -160 + (($i+1)*80), 150, $black);
//this function does the magic
function WriteTextForMe($im, $font, $text, $x1, $y1, $x2, $y2, $allocatedcolor)
{
//draw bars
imagesetthickness($im, 2);
imagerectangle($im, $x1, $y1, $x2, $y2, imagecolorallocate($im, 100,100,100));
//draw text with dynamic stretching
$maxwidth = $x2 - $x1;
for($size = 1; true; $size+=1)
{
$bbox = imagettfbbox($size, 0, $font, $text);
$width = $bbox[2] - $bbox[0];
if($width - $maxwidth > 0)
{
$drawsize = $size - 1;
$drawX = $x1 + $lastdifference / 2;
break;
}
$lastdifference = $maxwidth - $width;
}
$size--;
imagettftext($im, $drawsize, 0, $drawX, $y1 - 2, $allocatedcolor, $font, $text);
}
// Output to browser
header('Content-type: image/png');
imagepng($im);
imagedestroy($im);
?>
It uses imagettfbbox function to get width of the text, then loops over the font size to get correct size, centers it and displays it.
So, it outputs the following:
You can calculate the center of your text by using PHP's imagettfbbox-function:
// define text and font
$text = 'some bar label';
$font = 'path/to/some/font.ttf';
// calculate text size (this needs to be adjusted to suit your needs)
$size = 10 / (strlen($text) * 0.1);
// calculate bar center
$barCenter = $x1 + ($x2 - $x1) / 2;
// calculate text position (centered)
$bbox = imagettfbbox($size, 0, $font, $text);
$textWidth = $bbox[2] - $bbox[0];
$positionX = $textWidth / 2 + $barCenter;
$positionY = $y1 - $size;
EDIT: Updated the code to do all the work for you.

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