|
Five bitmap fonts are provided with gd: gdFontTiny, gdFontSmall, gdFontMediumBold, gdFontLarge, and gdFontGiant. These fonts are identified for use in the image functions, in order, by the integers 1-5.
|
|
int imageString ( resource image, int font, int x, int y, string s, int color )
Draws the string s in the image identified by image at coordinates x, y (top left is 0, 0) with the color color.
int imageStringUp ( resource image, int font, int x, int y, string s, int color )
Draws the string s vertically in the image identified by image at coordinates x, y (top left is 0, 0) with the color color.
int imageChar ( resource image, int font, int x, int y, string c, int color )
Draws the first character of c in the image identified by id with its upper-left at x, y (top left is 0, 0) with the color color.
int imageCharUp ( resource image, int font, int x, int y, string c, int color )
Draws the first character of c vertically in the image identified by image at coordinates x, y (top left is 0, 0) with the color color.
|
|
|
 |
| In order to calculate the position of text within an image, there are two useful functions to help determine how much space a character will require. |
int imageFontHeight ( int font )
Returns the pixel height of a character in the specified font.
int imageFontWidth ( int font )
Returns the pixel width of a character in the specified font.
|
| In the imageString() example above (simplestring.php), the default $x value is set to center the input string by calculating half of the total of the font width multiplied by the number of characters in the string, then subtraced from the image width: |
<?PHP
error_reporting(E_ALL ^ E_NOTICE);
/*
simplestring.php
Generates image of a colored box with text
*/
$wd = 400 ;
$ht = 40 ;
// convert guaranteed valid hex value to array of integers
$bkgColor = hex2int(validHexColor($_REQUEST['bColor']));
$txtColor = hex2int(validHexColor($_REQUEST['tColor'],'ffffff'));
if ($txtColor === $bkgColor) $bkgColor = hex2int('FFFFFF') ;
$font = (is_numeric($_REQUEST['font'])) ? max(min($_REQUEST['font'], 5),1):3;
$string = safeString($_REQUEST['string']) ;
// if a number is passed for x, make sure it is > 0 and < image width - string width
$x = (is_numeric($_REQUEST['x']))
? max(min($_REQUEST['x'],$wd - ceil( imageFontWidth($font) * strlen($string))),0)
: ceil(($wd - (imageFontWidth($font) * strlen($string)))/2);
// if a number is passed for 7, make sure it is > 0 and < image height - string height
$y = (is_numeric($_REQUEST['y']))
? max(min($_REQUEST['y'],$ht - imageFontHeight($font)),0)
: ceil(($ht - imageFontHeight($font)) / 2) ;
$im = imageCreate($wd,$ht);
$bkgC = imageColorAllocate($im, $bkgColor['r'], $bkgColor['g'], $bkgColor['b']);
$txtC = imageColorAllocate($im, $txtColor['r'], $txtColor['g'], $txtColor['b']);
imageString($im,$font,$x,$y,$string,$txtC) ;
// send headers, output & destroy
header('Content-type: image/png');
imagePNG($im);
imageDestroy($im);
/**
* @param $hex string 6-digit hexadecimal color
* @return array 3 elements 'r', 'g', & 'b' = int color values
* @desc Converts a 6 digit hexadecimal number into an array of
* 3 integer values ('r' => red value, 'g' => green, 'b' => blue)
*/
function hex2int($hex) {
return array( 'r' => hexdec(substr($hex, 0, 2)), // 1st pair of digits
'g' => hexdec(substr($hex, 2, 2)), // 2nd pair
'b' => hexdec(substr($hex, 4, 2)) // 3rd pair
);
}
/**
* @param $input string 6-digit hexadecimal string to be validated
* @param $default string default color to be returned if $input isn't valid
* @return string the validated 6-digit hexadecimal color
* @desc returns $input if it is a valid hexadecimal color,
* otherwise returns $default (which defaults to black)
*/
function validHexColor($input = '000000', $default = '000000') {
// A valid Hexadecimal color is exactly 6 characters long
// and eigher a digit or letter from a to f
return (eregi('^[0-9a-f]{6}$', $input)) ? $input : $default ;
}
function safeString($input) {
return stripslashes($input) ;
}
?>
|
| In addition to the fonts distributed with gd, you can also use any bitmap fonts installed on the system. The font file format is binary and architecture dependent. Since this introduction is intended to be run on several environments, there will be no demonstration of this function. |
int imageLoadFont ( string file )
Loads a user-defined bitmap font and returns an identifier for the font (that is always greater than 5, so it will not conflict with the built-in fonts). |