GD and Image 函数
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imagetypes

(PHP 4 >= 4.0.2, PHP 5)

imagetypes — 返回当前 PHP 版本所支持的图像类型

说明

int imagetypes ( void )

本函数以比特字段方式返回与当前 PHP 版本关联的 GD 库所支持的图像格式。将返回以下结果，IMG_GIF | IMG_JPG | IMG_PNG | IMG_WBMP| IMG_XPM。 例如要检查是否支持 PNG，这样做：

Example #1 imagetypes() 例子

<?php
if (imagetypes() & IMG_PNG) {
    echo "PNG Support is enabled";
}
?>

GD and Image 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: 返回当前 PHP 版本所支持的图像类型

用户评论:

ThunderCrew (31-Jul-2007 03:38)

Im not a smart man but this seemd to be the simplest code and it worked.
Its at the very top of this directory.

<?php
var_dump(gd_info());
?>

Returned image info and more.

array(11) { ["GD Version"]=> string(27) "bundled (2.0.28 compatible)" ["FreeType Support"]=> bool(true) ["FreeType Linkage"]=> string(13) "with freetype" ["T1Lib Support"]=> bool(false) ["GIF Read Support"]=> bool(true) ["GIF Create Support"]=> bool(true) ["JPG Support"]=> bool(true) ["PNG Support"]=> bool(true) ["WBMP Support"]=> bool(true) ["XBM Support"]=> bool(true) ["JIS-mapped Japanese Font Support"]=> bool(false) }

enyo (06-Nov-2003 03:32)

Why not use this function?

<?php
function getSupportedImageTypes() {
    $aSupportedTypes = array();

    $aPossibleImageTypeBits = array(
        IMG_GIF=>'GIF',
        IMG_JPG=>'JPG',
        IMG_PNG=>'PNG',
        IMG_WBMP=>'WBMP'
    );

    foreach ($aPossibleImageTypeBits as $iImageTypeBits => $sImageTypeString) {
        if (imagetypes() & $iImageTypeBits) {
            $aSupportedTypes[] = $sImageTypeString;
        }
    }

    return $aSupportedTypes;
}
?>

jocke at selincite dot IHATESP4M dot com (16-Oct-2003 10:56)

I wrote this function that returns an array with the supported image types

<?php
function getSupportedImageTypes() {
        $aSupportedTypes = array();
       
        $aPossibleImageTypeBits = array(
                "IMG_GIF",
                "IMG_JPG",
                "IMG_PNG",
                "IMG_WBMP"
            );
           
        foreach ($aPossibleImageTypeBits as $iIndex => $sImageTypeBits) {
           
            $sEval  = "if (";
            $sEval .= "imagetypes() & " . $sImageTypeBits . "";
            $sEval .= ") { return TRUE; } else { return FALSE; }";
           
            if (eval($sEval)) {
                $aSupportedTypes[] = str_replace("IMG_", "", $sImageTypeBits);
            }
        }
       
        return $aSupportedTypes;
    }
?>
Hope that helps someone :)

/Jocke Selin

PS, if you know of a better way that doesn't include eval(), please let me know.

jaldinger (at) consulturdorado (dot) com (08-Jan-2003 08:31)

Please note that if only "GIF Read Support" is enabled, the
IMG_GIF bit will not be returned (at least on my system:
PHP 4.3.0/RH Linux 7.2).

To work around this issue, and also the issue that there is no
function that can tell me what image format a GD resource ID
refers to, I use the following switch statement to map the exif
IMAGETYPE_* constants to the GD IMG_* constants:

switch (exif_imagetype($file['tmp_name'])) {
    case IMAGETYPE_GIF:
        $image_type = IMG_GIF;
        break;
    case IMAGETYPE_JPEG:
        $image_type = IMG_JPG;
        break;
    case IMAGETYPE_PNG:
        $image_type = IMG_PNG;
        break;
    case IMAGETYPE_WBMP:
        $image_type = IMG_WBMP;
        break;
     default:
        $image_type = 0;
        break;
}

store this value together with the image data in a database
and later use the following IF statement to see if I can work
with that image (create a thumbnail, etc...)

if ($image_type & (imagetypes() | IMG_GIF)) {
    return $this->createJpegThumbailFromString($data, 46, 27);
} else {
    return file_get_contents($_SERVER['DOCUMENT_ROOT'] .
        '/gfx/no-thumbnail.jpg');
}

HTH anybody...

Joerg.