imageftbbox()

(PHP 4 >= 4.0.7, PHP 5, PHP 7)

给出一个使用 FreeType 2 字体的文本框

说明

imageftbbox(float $size,float $angle,string $fontfile,string $text[,array $extrainfo]): array

This function calculates and returns the bounding box in pixels for a FreeType text.

参数

$size

字体的尺寸。根据 GD 的版本，为像素尺寸（GD1）或点（磅）尺寸（GD2）。

$angle

Angle in degrees in which$textwill be measured.

$fontfile

The name of the TrueType font file(can be a URL). Depending on which version of the GD library that PHP is using, it may attempt to search for files that do not begin with a leading '/' by appending '.ttf' to the filename and searching along a library-defined font path.

$text

The string to be measured.

$extrainfo

Possible array indexes for$extrainfo

Key	Type	Meaning
linespacing	float	Defines drawing linespacing

返回值

imageftbbox() returns an array with 8 elements representing four points making the bounding box of the text:

The points are relative to thetextregardless of the$angle, so "upper left" means in the top left-hand corner seeing the text horizontally.

范例

imageftbbox() example

<?php
// Create a 300x150 image
$im = imagecreatetruecolor(300, 150);
$black = imagecolorallocate($im, 0, 0, 0);
$white = imagecolorallocate($im, 255, 255, 255);
// Set the background to be white
imagefilledrectangle($im, 0, 0, 299, 299, $white);
// Path to our font file
$font = './arial.ttf';
// First we create our bounding box
$bbox = imageftbbox(10, 0, $font, 'The PHP Documentation Group');
// This is our cordinates for X and Y
$x = $bbox[0] + (imagesx($im) / 2) - ($bbox[4] / 2) - 5;
$y = $bbox[1] + (imagesy($im) / 2) - ($bbox[5] / 2) - 5;
imagefttext($im, 10, 0, $x, $y, $black, $font, 'The PHP Documentation Group');
// Output to browser
header('Content-Type: image/png');
imagepng($im);
imagedestroy($im);
?>

注释

Note:此函数需要 GD 2.0.1 或更高版本(推荐 2.0.28 及更高版本)。

Note:此函数仅在PHP 编译时加入 freetype 支持时有效（--with-freetype-dir=DIR）。

更新日志

imagettfbbox() returns an array with 8 elements representing four points making the bounding box of the text: 
0 lower left corner, X position 
1 lower left corner, Y position 
2 lower right corner, X position 
3 lower right corner, Y position 
4 upper right corner, X position 
5 upper right corner, Y position 
6 upper left corner, X position 
7 upper left corner, Y position 
The points are relative to the text regardless of the angle, so "upper left" means in the top left-hand corner seeing the text horizontally.

Here is a handy example I used to center "dynamic text" onto an image. 
Ex. Say you want to center a clients IP Address onto a picture. 
$ip=$_SERVER['REMOTE_ADDR'];  
$details = imageftbbox($fontsize, 0, $font, $ip, array("linespacing" => 1));
$xcoord = ($imgwidth - $details[4]) / 2; // this will return the x coordinate centered to your specific image. Make sure you set $imgwidth to the width of the image you are using.   
imagettftext($image, $fontsize, 0, $xcoord, $ycoord, $fontcolor, $font, $ip);

This function can be used to generate right-aligned text. Just work out how wide the text image is and position it accordingly. Example:
$i_width = 200;
$i_height = 40;
$string = "Hello World!";
$pointsize = 10;
$fontfile = "/usr/local/lib/ttf/Helve.ttf";
$im = imagecreate($i_width, $i_height);
$black = imagecolorallocate ($im, 0, 0, 0);
$white = imagecolorallocate ($im, 255, 255, 255);
$string_size = ImageFtBbox($pointsize, 0, $fontfile, $string, array("linespacing" => 1));
$s_width = $string_size[4];
$s_height = $string_size[5];
ImageFtText($im, $pointsize, 0, $i_width - $s_width - 1, 0 - $s_height, $white, $fontfile, $string, array("linespacing" => 1));
Header ("Content-type: image/png");
ImagePNG ($im);
ImageDestroy ($im);

//EXAMPLE - Center text
function newText($im, $size, $angle= 0, $x, $y, $color, $font, $text,$align = "left",$border=false,$width=0,$height=0){
  
  if($align == "center")
  {
    if ($border == true ){
      imagerectangle($im, $x, $y, $x +$width, $y + $height, $color);
    }
    $bbox = imageftbbox($size, 0, $font, $text);
    // Marcamos el ancho y alto
    $s_width = $bbox[4];
    $s_height = $bbox[5]; 
    
    $y = $y + ($height-$s_height)/2;
    $x = $x + ($width-$s_width)/2;
  }
   
  imagettftext($im, $size, $angle, $x, $y, $color, $font, $text);
}

ah... the problem between imageftbbox() and imagefttext() lies in the mirroring of the y-axes.
Below you see, for a font-size 16 the boudingboxes of "b", "p" and "bp":
< b: w=9 h=15
b(0,-1)
b(9,-1)
b(9,-16)
b(0,-16)
< p: w=9 h=16
p(0,4)
p(9,4)
p(9,-12)
p(0,-12)
< bp: w=20 h=20
bp(0,4)
bp(20,4)
bp(20,-16)
bp(0,-16)
If drawing "bp" using imagefttext() at y=0, the the top of "bp" indeed is at y=-16, and the bottom of "bp" at y=4. (Plus or minus a pixel here and there, because at y=0 there actually is a vissible pixel.)

i've found a work around for this situation
it seems that height is directly proportional to line spacing so you just have to apply the same factor to image height
for example :
$spacing = 0.7;
$params = array("linespacing" => $spacing);
$box = imageftbbox ($size, 0, $font, $text, $params);
$tw=$box[4]-$box[0]; //image width
$th=($box[1]-$box[5])*$spacing; //image height

ImageFTBBox returns a bounding box, not metrics, as some (most?) of the notes above seem to assume. The 8 values it returns specify the 4 corners of this bounding box. So to properly determine the width and height of a string you need to do:
$bbox = ImageFTBBox(...);
$width = abs($bbox[0]) + abs($bbox[2]); // distance from left to right
$height = abs($bbox[1]) + abs($bbox[5]); // distance from top to bottom

For alignment i used this method:
if($align == "center" || $align == "right")
  {
    $verticaltxtspace = $backwidth - (2 * $posx);    
    $spacepositions = imagettfbbox($size, $angle, "fonts/verdanaz.ttf", " ");     
    $spacepx = $spacepositions[4] - $spacepositions[0];    
    
    // Split text in lines
    $lines = split("[\r][\n]", $text);    
    for($count = 0; $count < count($lines); $count++)
    {
      $textpositions = imagettfbbox($size, $angle, "fonts/verdanaz.ttf", $lines[$count]);      
      $textpx = $textpositions[2] - $textpositions[0];
      
      if($align == "right")
      {
        $spaces = ($verticaltxtspace - $textpx) / $spacepx;
      }
      else if($align == "center")
      {
        $spaces = (($verticaltxtspace - $textpx)/2) / $spacepx;
      }
      
      // Add spaces
      $line = $lines[$count];
      for($i = 0; $i < $spaces; $i++)
      {
        $line = " " . $line;
      }
      $lines[$count] = $line;
    }
    
    // Create new text of lines
    $text = "";
    for($count = 0; $count < count($lines); $count++)
    {
      $text .= $lines[$count] . "\r\n";
    }    
  }
  
    
  //  Draw the shadow text on de shadow
  imagettftext($background, $size, $angle, $posx, $posy, $textcolor, "fonts/verdanaz.ttf", $text);