javascript 将画布解码为 dataURL
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/7291183/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Decoding a canvas todataURL
提问by joel
I'm having difficulty using data created with canvas's todataurl() method. Currently my code sends the resulting data to my php server which uses the file_put_contents() method to create a file to store that data. Now if I cut and paste the resulting gibberish from the file into an image tag src it works fine and displays properly so I assume so far everything is peachy.
我在使用用画布的 todataurl() 方法创建的数据时遇到了困难。目前，我的代码将结果数据发送到我的 php 服务器，该服务器使用 file_put_contents() 方法创建一个文件来存储该数据。现在，如果我将文件中产生的乱码剪切并粘贴到图像标签 src 中，它可以正常工作并正确显示，因此我认为到目前为止一切都很好。
But I keep running into issues when I try to use the code in JS. I've tried php's base64_decode method but kept getting currupt files. I found this code:
但是当我尝试在 JS 中使用代码时，我一直遇到问题。我试过 php 的 base64_decode 方法，但一直收到损坏的文件。我找到了这个代码：
<?php
$encodedData = str_replace(' ','+',$encodedData);
$decocedData = base64_decode($encodedData);
and still got currupted files. Ideally I'd like to create a .png file with it but I'd settle for just processing the data file again in JS. Any help greatly appreciated.
并且仍然有损坏的文件。理想情况下，我想用它创建一个 .png 文件，但我只想在 JS 中再次处理数据文件。非常感谢任何帮助。
回答by stewe
It seems you have to get rid of the header that is prepended to the image data by the toDataURL()function.
On the client side you can strip off the header like this:
看来您必须摆脱toDataURL()函数预先添加到图像数据的标题。在客户端，您可以像这样剥离标题：
..
var data=canvas.toDataURL();
var output=data.replace(/^data:image\/(png|jpg);base64,/, "");
// now send "output" to the server
..
On the server side use this:
在服务器端使用这个：
<?php
$decocedData = base64_decode($encodedData);
?>
回答by Daniel De León
In java script send the result from canvas.toDataURL() on those browsers than support this method with the default type of "image/png".
在 Java 脚本中，在那些浏览器上从 canvas.toDataURL() 发送结果，而不是使用默认类型“image/png”支持此方法。
var imageInfo = canvas.toDataURL();
// now send "imageInfo" to the server
Direct way to create the png file:
直接创建png文件的方法：
<?php
$imageInfo = imageInfoFromBrowser(); // Your method to get the data
$image = fopen($imageInfo, 'r');
file_put_contents("fileName.png", $image);
fclose($image);
?>
I have this working in PHP 5.3 / Windows, for other version, please check.
我在 PHP 5.3 / Windows 上有这个工作，对于其他版本，请检查。
Image data sample for testing on PHP.
用于在 PHP 上进行测试的图像数据示例。
$imageInfo = "data:image/png;base64,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"
回答by hiddentstones
Another important note is you have to convert blanks into plusses. If you do not do that, the decoded data is corrupted:
另一个重要的注意事项是您必须将空格转换为加号。如果你不这样做，解码的数据就会损坏：
$encodedData = str_replace(' ','+',$encodedData);
$decocedData = base64_decode($encodedData);
You can read more at http://www.php.net/manual/en/function.base64-decode.php
您可以在http://www.php.net/manual/en/function.base64-decode.php阅读更多信息
回答by lost in binary
Other solutions did not work for me.
其他解决方案对我不起作用。
This works:
这有效：
//image sample
$baseFromJavascript = "data:image/png;base64,BBBFBfj42Pj4";
// remove the part that we don't need from the provided image and decode it
$data = base64_decode(preg_replace('#^data:image/\w+;base64,#i', '', $baseFromJavascript));
