imagetypes

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：
例子 1. imagetypes() 例子
<?php if (imagetypes() & IMG_PNG) { echo "PNG Support is enabled"; } ?>

add a note User Contributed Notes

enyo
06-Nov-2003 11:32


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
17-Oct-2003 05:56


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
09-Jan-2003 04:31


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.

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