imagerotate()中的背景transperancy

Question

从最近2天开始,我试图在使用imagerotate()PHP-GD函数旋转图像后为后台添加transperancy.

但是,令我非常失望的是,它根本不起作用.

它只是在它后面发出黑色背景.

这是我的代码 -

$patchImageS    =   'image.png'; // the image to be patched over the final bg
$patchImage =   imagecreatefrompng($patchImageS); // resource of image to be patched
$patchImage     =   imagerotate($patchImage, 23, 0, 0);
imagepng($patchImage,'tt.png');

我试图将函数中传递的参数更改为

imagerotate($ patchImage,23,5,0);

imagerotate($ patchImage,23,0,5);

任何帮助将受到高度赞赏.

Answer 1

经过多次99%的答案后,我找到了解决方案:

// Create, or create from image, a PNG canvas
$png = imagecreatetruecolor($width, $height);

// Preserve transparency
imagesavealpha($png , true);
$pngTransparency = imagecolorallocatealpha($png , 0, 0, 0, 127);
imagefill($png , 0, 0, $pngTransparency);

// Rotate the canvas including the required transparent "color"
$png = imagerotate($png, $rotationAmount, $pngTransparency);

// Set your appropriate header
header('Content-Type: image/png');

// Render canvas to the browser
imagepng($png);

// Clean up
imagedestroy($png);

这里的关键是在imagerotate()调用中包含你的imagecolorallocatealpha()...