用php旋转png图像后如何获得透明背景？

Question

所以我有 png 图像，我旋转它，但我得到黑色背景..或者如果我执行白色的颜色代码，我会得到白色..我尝试这样做..

$trans = imagecolorallocatealpha(image, 0, 0, 0, 127);
imagerotate($image, $degree, $trans)

我也尝试过..

$trans = imagecolorallocatealpha($image, 255, 255, 255, 127);

有人可以帮助我吗？

这是我的代码..如果我将 allocatealpha 更改为 0, 0, 255, 0 那么它会变成蓝色。但使用 0, 0, 0, 127 时它仍然是黑色的。

function rotate($degrees) {
    $image = $this->image;
    imagealphablending($image, false);
    $color = imagecolorallocatealpha($image, 0, 0, 0, 127);
    imagefill($this->image, 0, 0, $color);
    $rotate = imagerotate($image, $degrees, $color);
    imagesavealpha($image, TRUE);
    $this->image = $rotate;
}

Answer 1

$destimg = imagecreatefromjpeg("image.png");
$transColor = imagecolorallocatealpha($destimg, 255, 255, 255, 127);
$rotatedImage = imagerotate($destimg, 200, $transColor);
imagesavealpha($rotatedImage, true);
imagepng($rotatedImage,"rotated.png");

---

根据下面的正确评论，这应该是：

$destimg = imagecreatefrompng("image.png");
$transColor = imagecolorallocatealpha($destimg, 255, 255, 255, 127);
$rotatedImage = imagerotate($destimg, 200, $transColor);
imagesavealpha($rotatedImage, true);
imagepng($rotatedImage,"rotated.png");

Answer 2

确保将 imagesavealpha 设置为 TRUE 以保留透明度。 http://www.php.net/manual/en/function.imagesavealpha.php

imagesavealpha($image, TRUE);

Answer 3

你试过这个吗？

imagecolortransparent

希望我理解你的问题！

Answer 4

        // Turn off transparency blending (temporarily)
        imagealphablending($image, false);

        // Create a new transparent color for image
        $color = imagecolorallocatealpha($image, 0, 0, 0, 127);

        // Completely fill the background of the new image with allocated color.
        imagefill($image, 0, 0, $color);

        // Restore transparency blending
        imagesavealpha($image, true);

Answer 5

您可以尝试以下操作：http://www.exorithm.com/algorithm/view/rotate_image_alpha

Answer 6

    $info = pathinfo($pathToImage);
    $name = str_replace("." . $info['extension'], "", $info['basename']);

    $size = getimagesize($pathToImage);



    $type = isset($size['type']) ? $size['type'] : $size[2];

    // Check support of file type
    if (!(imagetypes() & $type)) {
        // Server does not support file type
        return false;
    }

    $source = self::imageCreateFrom($pathToImage, trim($info['extension'])) or notfound();
    $transColor = imagecolorallocatealpha($source, 255, 255, 255, 127);

    // $transparency = imagecolorallocatealpha($source, 0, 0, 0, 127);
    $rotate = imagerotate($source, 360 - $rotate_angle, $transColor);
    //imagealphablending($rotate, false);


    imagesavealpha($rotate, TRUE);
    //imagejpeg($rotate,$pathToThumbs.DIRECTORY_SEPARATOR.$info['basename']);
    self::createImage($rotate, $pathToThumbs, $info['basename'], trim($info['extension']));

    // imagejpeg($rotate);
    imagedestroy($source);
    imagedestroy($rotate);

Answer 7

这就是我正在使用的，这对于具有透明背景的 .png 文件非常有用。击掌！

function rotate($degrees) {

    // Switch from default counter-clockwise to clockwise
    $degrees = 360 - $degrees; 

    // Get the image 
    $source =  imagecreatefrompng("images/image.png");

    // Rotate the image
    $rotated_image = imagerotate($source, $degrees, imageColorAllocateAlpha($source, 0, 0, 0, 127));

    // Save the rotated image
    imagepng($rotated_image, 'images/rotated_image.png');

}