imagefontheight

(PHP 4, PHP 5, PHP 7, PHP 8)

imagefontheight获取字体高度

说明

imagefontheight(GdFont|int $font): int

返回指定字体中字符的像素高度。

参数

font

取值对于内建的 latin2 编码字体可以是:1、2、3、4、5(更高的数字对应更大的字体), 或是通过 imageloadfont() 返回的 GdFont 实例。

返回值

返回字体的像素高度。

更新日志

版本 说明
8.1.0 font 参数现在接受 GdFont 实例和 int,之前仅接受 int

示例

示例 #1 在内置字体上使用 imagefontheight()

<?php
echo 'Font height: ' . imagefontheight(4);
?>

以上示例的输出类似于:

Font height: 16

示例 #2 将 imagefontheight()imageloadfont() 一起使用

<?php
// Load a .gdf font
$font = imageloadfont('anonymous.gdf');

echo
'Font height: ' . imagefontheight($font);
?>

以上示例的输出类似于:

Font height: 43

参见

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User Contributed Notes 1 note

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1
dev at numist dot net
19 years ago
This library function is very useful for variable-sized images that only contain text, like this function that I use to output error messages that accumulate and cause a fatal error in my thumbnailer:

<?php
function errimg($error) {
  
// $error is an array of error messages, each taking up one line
   // initialization
  
$font_size = 2;
  
$text_width = imagefontwidth($font_size);
  
$text_height = imagefontheight($font_size);
  
$width = 0;
  
// the height of the image will be the number of items in $error
  
$height = count($error);

  
// this gets the length of the longest string, in characters to determine
   // the width of the output image
  
for($x = 0; $x < count($error); $x++) {
      if(
strlen($error[$x]) > $width) {
        
$width = strlen($error[$x]);
      }
   }
  
  
// next we turn the height and width into pixel values
  
$width = $width * $text_width;
  
$height = $height * $text_height;
  
  
// create image with dimensions to fit text, plus two extra rows and
   // two extra columns for border
  
$im = imagecreatetruecolor($width + ( 2 * $text_width ),
                             
$height + ( 2 * $text_height ) );
   if(
$im) {
     
// image creation success
     
$text_color = imagecolorallocate($im, 233, 14, 91);
     
// this loop outputs the error message to the image
     
for($x = 0; $x < count($error); $x++) {
        
// imagestring(image, font, x, y, msg, color);
        
imagestring($im, $font_size, $text_width,
                    
$text_height + $x * $text_height, $error[$x],
                    
$text_color);
      }
     
// now, render your image using your favorite image* function
      // (imagejpeg, for instance)
     
out($im, array(), $error);
   } else {
     
// image creation failed, so just dump the array along with extra error
     
$error[] = "Is GD Installed?";
      die(
var_dump($error));
   }
}
?>

The function expects an array of error messages to be passed in, and then outputs an image containing the contents of the array.  This is especially useful if your code is contained in an html page that will display rexes if the images do not render correctly.

This function displays the array in image form with index 0 at the top, and the highest index at the bottom.

You have to write out() yourself though, see imagejpeg, imagepng, etc for good ideas on how to write a decent output function.
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