PHP GD：如何将图像数据作为二进制字符串获取？
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PHP GD: How to get imagedata as binary string?
提问by Cambiata
I'm using a solution for assembling image files to a zip and streaming it to browser/Flex application. (ZipStream by Paul Duncan, http://pablotron.org/software/zipstream-php/).
我正在使用一种解决方案将图像文件组装到 zip 并将其流式传输到浏览器/Flex 应用程序。（Paul Duncan 的 ZipStream，http://pablotron.org/software/zipstream-php/ ）。
Just loading the image files and compressing them works fine. Here's the core for compressing a file:
只需加载图像文件并压缩它们就可以正常工作。这是压缩文件的核心：
// Reading the file and converting to string data
$stringdata = file_get_contents($imagefile);
// Compressing the string data
$zdata = gzdeflate($stringdata );
My problem is that I want to process the image using GD before compressing it. Therefore I need a solution for converting the image data (imagecreatefrompng) to string data format:
我的问题是我想在压缩之前使用 GD 处理图像。因此，我需要一个将图像数据 (imagecreatefrompng) 转换为字符串数据格式的解决方案：
// Reading the file as GD image data
$imagedata = imagecreatefrompng($imagefile);
// Do some GD processing: Adding watermarks etc. No problem here...
// HOW TO DO THIS???
// convert the $imagedata to $stringdata - PROBLEM!
// Compressing the string data
$zdata = gzdeflate($stringdata );Any clues?
有什么线索吗？
回答by spoulson
One way is to tell GD to output the image, then use PHP buffering to capture it to a string:
一种方法是告诉GD输出图像，然后使用PHP缓冲将其捕获为字符串：
$imagedata = imagecreatefrompng($imagefile);
ob_start();
imagepng($imagedata);
$stringdata = ob_get_contents(); // read from buffer
ob_end_clean(); // delete buffer
$zdata = gzdeflate($stringdata);
回答by Stefan Brinkmann
// ob_clean(); // optional
ob_start();
imagepng($imagedata);
$image = ob_get_clean();
回答by M.i.X
The php://memory stream can be used when output-buffer juggling is unwanted. https://www.php.net/manual/en/wrappers.php.php
当不需要输出缓冲区杂耍时，可以使用 php://memory 流。 https://www.php.net/manual/en/wrappers.php.php
$imagedata = imagecreatefrompng($imagefile);
// processing
$stream = fopen('php://memory','r+');
imagepng($imagedata,$stream);
rewind($stream);
$stringdata = stream_get_contents($stream);
// Compressing the string data
$zdata = gzdeflate($stringdata );
