GD and Image 函数
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imageftbbox

(PHP 4 >= 4.0.7, PHP 5)

imageftbbox — 给出一个使用 FreeType 2 字体的文本框

说明

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

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:

extrainfo 参数自 PHP 4.3.5 起成为可选项。

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 text will 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:

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.

范例

Example #1 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

版本 说明
4.3.5 extrainfo was made optional.

GD and Image 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: 给出一个使用 FreeType 2 字体的文本框

用户评论:

Johan (19-Nov-2007 03:38)

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);

theo v e -2 (28-Dec-2005 03:10)

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.)

theo v e (28-Dec-2005 02:20)

IF we accept the idea that a bouding box is returned then:
    $bbox= imageftbbox ( $size, $angle, $font, $txt);
    $width = abs($bbox[4] - $bbox[0]);
    $height = abs($bbox[1] - $bbox[5]);
may be a better kind of math. But it depends... You may want to subtract yet another '1' from both the width and the height.
But try drawing a "p" and next try a "d". Their bounding boxes differ 1 px in height. Of course the respective boxes, by  imagefttext(), are placed at a different y coordinate. I noticed that if a "p" or a "b" is drawn at (0, 30) the first character of the string actually starts on, fills, the third horizontal pixel. Also: if your image is only 30 pixels in heigth, drawing text at (0, 30) means that the bottoms parts of "p", "q", "y" and alike are somewhere else...

fernando (14-Jul-2005 09:20)

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.

groomed at users dot sf dot net (27-May-2004 08:38)

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

sectionthirty1 at yahoo dot com (22-Apr-2004 10:50)

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);

Brian at PrintsMadeEasy dot com (07-Mar-2003 03:54)

I noticed that PHP's True Type functions do not allow you to create text blocks with multiple lines that automatically adjust for alignment.  I wrote a function that will allow you to generate images with multiple lines, control the alignment, and handle rotation.  I hope it helps someone.

There was too much code to paste on this message post so you can grab it off of my webserver.  I also created an example page so that you can see the code in action.

Example Page:
http://www.PrintsMadeEasy.com/code_samples/php/text_generation.php

Download the Text file:
http://www.PrintsMadeEasy.com /code_samples/php/text_generation.txt

ta at NOSPAM dot magicsquare dot info (06-Sep-2002 05:37)

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

phpimageftbbox at juggernaut dot com dot au (15-May-2002 05:56)

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);