Show A Base64 Image On PHP Page Using Image header() & readfile()

问题

I am working on a script where after some operation of PHP functions, I generate a base64 image data in $base64Image variable. Now I want to show that base64 image data as a full image on the web browser same as an image.jpeg. For this purpose, I wrote some codes as shown below...

screenshot.php

<?php
/*------------------------
// Basic PHP Operations //
------------------------*/
// Get URL Parameters
$key1 = $_GET["key1"];
$key2 = $_GET["key2"];

// Some PHP Operations...........................................................................

// An Example base64 Image Else This Variable Will Be Filed After Some PHP Operations
$base64Image = "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";

// Convert base64 Image to Real Image
$imageFile = base64_decode($base64Image);

// Get Image filesize For Header
$filesize = filesize($imageFile);

/*-------------------------------------------------
// Image Output (Convert PHP File In Image File) //
-------------------------------------------------*/
header( 'Pragma: public' );
header( 'Expires: 0' );
header( 'Cache-Control: must-revalidate, post-check=0, pre-check=0' );
header( 'Cache-Control: private',false );
header( 'Content-Disposition: attachment; filename="screenshot.png"' ); // Default File Name Will Be "screenshot.png"
header( 'Content-Transfer-Encoding: binary' );
header('Content-Type: image/png');      // Becasue Base64 Image Is Of PNG Type Fixed
header( 'Content-Length: '.$filesize );
readfile( $imageFile );
?>

And I am trying to display the upper image in an HTML file as shown below.

screenshot.html

<img src="screenshot.php?key1=value1&key2=value2" alt="screenshot"/>

After all of these tries, I am still not able to to see my image directly in .php the page or in .html page. Anyway thanks in advance.

Note: I do not want to force the downloading of images. Even if someone tries to open screenshot.php, it should show the image on browser page not to download.

回答1:

You can't use filesize() on a string, also the Content-Disposition: attachment header forces a download.

Change everything under the base64 to:

header( 'Pragma: public' );
header( 'Expires: 0' );
header( 'Cache-Control: must-revalidate, post-check=0, pre-check=0' );
header( 'Cache-Control: private',false );
header( 'Content-Transfer-Encoding: binary' );
header('Content-Type: image/png');      // Becasue Base64 Image Is Of PNG Type Fixed
echo $imageFile

I'm not even sure you need most of those headers, when I tested it I just used Content-Type.

来源：https://stackoverflow.com/questions/62047610/show-a-base64-image-on-php-page-using-image-header-readfile