PHP 类生成图像的问题
我编写了这段代码：
class Generate{
private $canvas;
function __construct($width, $height){
$this->canvas = imagecreatetruecolor($width, $height);
}
public function bg($r=0,$g=0,$b=0){
$color = imagecolorallocate($this->canvas, $r, $g, $b);
imagefill($this->canvas, 0, 0, $color);
}
public function gen(){
header('Content-Type: image/png');
imagepng($this->canvas, NULL, 9);
imagedestroy($this->canvas);
}
}
并用以下方式调用它：
$G = new Generate(100, 100);
$G->bg(255, 255, 255);
$G->gen();
当我注释掉 gen() 函数中的标头并将其设置为保存图像时，它生成的图像很好。像这样：
imagepng($this->canvas, 'img.png', 9);
但我希望它发送标头（输出图像），但它给了我一个错误。有人可以告诉我我做错了什么吗？你甚至可以在 PHP 类中发送标头吗？
当我不使用 OOP 时，这段代码工作正常
i wrote this code:
class Generate{
private $canvas;
function __construct($width, $height){
$this->canvas = imagecreatetruecolor($width, $height);
}
public function bg($r=0,$g=0,$b=0){
$color = imagecolorallocate($this->canvas, $r, $g, $b);
imagefill($this->canvas, 0, 0, $color);
}
public function gen(){
header('Content-Type: image/png');
imagepng($this->canvas, NULL, 9);
imagedestroy($this->canvas);
}
}
and called it with this:
$G = new Generate(100, 100);
$G->bg(255, 255, 255);
$G->gen();
its generating image fine when i comment out the header in the gen() function and set it to save the image. Like this:
imagepng($this->canvas, 'img.png', 9);
but i want it to send the header(output the image) but it gives me an error. can someone please tell me what i'm doing wrong? can you even send headers with-in a PHP class?
this code works fine when i don't use OOP
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您问题的答案是，您可以。您可以在将任何输出发送给客户端之前随时发送标头，我怀疑这是您的问题。
您还可以检查要保存文件的编码。如果将文件保存为UTF-8，请确保在没有字节订单标记的情况下保存它。这将其视为输出，并且将始终是文件中的第一个字符，意味着
header（）的任何调用都会生成警告。The answer to your question is yes, you can. You can send headers at any time before you send any output to the client, which I suspect is what your issue is.
You can also check the encoding that you're saving your file in. If you are saving your file as UTF-8, make sure you save it without a byte order mark. This counts as output, and will always be the first character in your file meaning any call to
header()will generate a warning.当您发布时，该代码对我来说非常适合我；您确定您不仅在白色背景上丢失了100x100白色图像吗？尝试将颜色更改为
127,255,255（可爱的aqua），看看它是否显示。The code works perfectly for me when I run it as you posted it; are you sure that you aren't just losing your 100x100 white image on a white background? Try changing the color to, say,
127,255,255(a lovely aqua) and see if it shows up.