png白色背景，但在OpenCart网站上变黑

Question

将.png图片上传到我的网站时，图片是透明的，直到我全屏打开它，然后它才变成黑色。您能告诉我是否有任何代码错误，该如何解决？

$image_old = $this - > image;
$this - > image = imagecreatetruecolor($width, $height);

if (isset($this - > info['mime']) && $this - > info['mime'] == 'image/png') {
    imagealphablending($this - > image, false);
    imagesavealpha($this - > image, true);
    $background = imagecolorallocatealpha($this - > image, 255, 255, 255,
        127);
    imagecolortransparent($this - > image, $background);
} else {
    $background = imagecolorallocate($this - > image, 255, 255, 255);
}

imagefilledrectangle($this - > image, 0, 0, $width, $height, $background);

imagecopyresampled($this - > image, $image_old, $xpos, $ypos, 0, 0,
    $new_width, $new_height, $this - > info['width'], $this - > info['height']);
imagedestroy($image_old);

$this - > info['width'] = $width;
$this - > info['height'] = $height;
}

public

function watermark($file, $position = 'bottomright') {
    $watermark = $this - > create($file);

    $watermark_width = imagesx($watermark);
    $watermark_height = imagesy($watermark);

    switch ($position) {
        case 'topleft':
            $watermark_pos_x = 0;
            $watermark_pos_y = 0;
            break;
        case 'topright':
            $watermark_pos_x = $this - > info['width'] - $watermark_width;
            $watermark_pos_y = 0;
            break;
        case 'bottomleft':
            $watermark_pos_x = 0;
            $watermark_pos_y = $this - > info['height'] - $watermark_height;
            break;
        case 'bottomright':
            $watermark_pos_x = $this - > info['width'] - $watermark_width;
            $watermark_pos_y = $this - > info['height'] - $watermark_height;
            break;
    }

    imagecopy($this - > image, $watermark, $watermark_pos_x, $watermark_pos_y,
        0, 0, 120, 40);

    imagedestroy($watermark);
}

public

function crop($top_x, $top_y, $bottom_x, $bottom_y) {
    $image_old = $this - > image;
    $this - > image = imagecreatetruecolor($bottom_x - $top_x, $bottom_y -
        $top_y);
    imagecopy($this - > image, $image_old, 0, 0, $top_x, $top_y, $this -
        >
        info['width'], $this - > info['height']);
    imagedestroy($image_old);
}

public

function rotate($degree, $color = 'FFFFFF') {
    $rgb = $this - > html2rgb($color);