PHP - 动态添加透明 PNG 到 GIF [英] PHP - Add transparent PNG to GIF dynamically

问题描述

我正在尝试使用 php 代码做水印标记，一切似乎都正常，直到我将透明的 PNG 文件放入 GIF.这会发生什么:

I am trying to do a watermark mark with the php code, and everything seems to work fine, until I put a transparent PNG file to a GIF. This what happens:

所以不是透明的黑色水印，我在顶部得到了这个半纯绿色的东西.水印是

So instead of transparent black watermark, I get this semi solid green thing on the top. The watermark is

我使用以下 php 代码:

I use the following php code:

    ...
    $image = imagecreatefromgif($filepath);;
    $watermark_image = imagecreatefrompng($wm_filepath);
    imagealphablending($watermark_image, false);
    imagesavealpha($watermark_image, true);
    imagegif($image, $filepath);
    imagedestroy($image);


    imagecopy($image, $watermark_image, $offset['x'], $offset['y'], 0, 0, imagesx($watermark_image), imagesy($watermark_image) );

附言我不得不提一下，我尝试使用

p.s. I have to mention that I tried to combine different settings using

    imagealphablending()
    imagesavealpha() 

没有结果

UPD:

现在我将图像保存为 png 文件.我删除了这两行 imagealphablending($watermark_image, false);imagesavealpha($watermark_image, true); 并且它起作用了.但是，PNG 的透明度与 GIF 重叠.imagealphablending($image, true); 没有帮助.我该怎么办?

Now I am saving image as a png file. I deleted these two rows imagealphablending($watermark_image, false); imagesavealpha($watermark_image, true); and it worked. However, the transparency of PNG is overlapping GIF. imagealphablending($image, true); didn't help. What shall I do?

推荐答案

GIF 文件限制为 256 种颜色，并且有一种指定为透明的颜色.所以你不能有抗锯齿透明度，也不能有任何类型的抗锯齿.

GIF files are limited to 256 colours and have a single colour designated as transparent. So you can't have antialiased transparency, nor can you have much antialiasing of any kind.

我建议另存为 PNG.

I suggest saving as PNG instead.

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