如何创建具有透明背景的图像 [英] How to create an image with transparent background
问题描述
如何使用具有透明背景的GDlib创建图像?
How to create an image with GDlib with a transparent background?
header('content-type: image/png');
$image = imagecreatetruecolor(900, 350);
imagealphablending($image, true);
imagesavealpha($image, true);
$text_color = imagecolorallocate($image, 0, 51, 102);
imagestring($image,2,4,4,'Test',$text_color);
imagepng($image);
imagedestroy($image);
这里的背景是黑色的
推荐答案
您必须使用imagefill()
,并用alpha设置为0的分配颜色(imagecolorallocatealpha()
)填充该颜色.
You have to use imagefill()
and fill that with allocated color (imagecolorallocatealpha()
) that have alpha set to 0.
正如@mvds所说,没有必要分配",如果它是真彩色图像(24或32位),则它只是一个整数,因此您可以将该整数直接传递给imagefill()
.
As @mvds said, "allocating isn't necessary", if it is a truecolor image (24 or 32bit) it is just an integer, so you can pass that integer directly to imagefill()
.
当您调用imagecolorallocate()
时,PHP在后台处理真彩色图像的方法是一样的-它只返回该计算出的整数.
What PHP does in the background for truecolor images when you call imagecolorallocate()
is the same thing - it just returns that computed integer.
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