PHP实现添加图片水印的示例代码

function _imgwatermark($src_image, $water_image, $path_image = '', $position = 10, $pct = 30, $angle = 15)
{
    // 检查源图和水印图文件是否存在
    if (!is_file($src_image)) {
        $error = '源图不存在';
        return false;
    }
    if (!is_file($water_image)) {
        $error = '水印图不存在';
        return false;
    }
 
    // 获取图片信息
    $src_info = getimagesize($src_image);
    $water_info = getimagesize($water_image);
 
    // 定义允许的图片 mime 类型
    $allow = array(
        'image/jpeg' => 'jpeg',
        'image/gif' => 'gif',
        'image/jpg' => 'jpg',
        'image/png' => 'png',
        'image/pjpeg' => 'jpeg'
    );
 
    // 检查图像类型是否被允许
    if (!array_key_exists($src_info['mime'], $allow)) {
        $error = "源图类型不支持添加水印";
        return false;
    }
    if (!array_key_exists($water_info['mime'], $allow)) {
        $error = "水印图类型不支持";
        return false;
    }
 
    // 根据 mime 类型创建打开和保存图片的函数
    $src_open = 'imagecreatefrom' . $allow[$src_info['mime']];
    $water_open = 'imagecreatefrom' . $allow[$water_info['mime']];
    $src_save = 'image' . $allow[$src_info['mime']];
 
    // 打开图像资源
    $src = $src_open($src_image);
    $water = $water_open($water_image);
 
    // 根据比例计算水印的新尺寸
    $scale_factor = 0.15; // 水印的相对大小比例
    $new_water_width = $src_info[0] * $scale_factor;
    $new_water_height = ($water_info[1] / $water_info[0]) * $new_water_width;
 
    // 创建缩放后的水印图
    $resized_water = imagecreatetruecolor($new_water_width, $new_water_height);
    imagealphablending($resized_water, false);
    imagesavealpha($resized_water, true);
    imagecopyresampled($resized_water, $water, 0, 0, 0, 0, $new_water_width, $new_water_height, $water_info[0], $water_info[1]);
 
    // 释放原始水印资源，使用缩放后的水印
    imagedestroy($water);
    $water = $resized_water;
    $water_info[0] = $new_water_width;
    $water_info[1] = $new_water_height;
 
    if ($angle) {
        // 旋转水印图片
        $water = imagerotate($water, $angle, imagecolorallocatealpha($water, 0, 0, 0, 127));
        // 获取旋转后的水印尺寸
        $sourceinfo[0] = imagesx($water);
        $sourceinfo[1] = imagesy($water);
        // 设置水印平铺的间距
        $ww = $src_info[0] * 0.1;  // 水平方向间距
        $hh = $src_info[1] * 0.1;  // 垂直方向间距
    }
 
    if ($position == 10) {
        $offset_x = $water_info[0] / 2;
    }
 
    // 计算水印在源图中的位置
    $start_x = $start_y = 0;
    switch ($position) {
        case 1:
            break;
        case 2:
            $start_x = floor(($src_info[0] - $water_info[0]) / 2);
            break;
        case 3:
            $start_x = $src_info[0] - $water_info[0];
            break;
        case 4:
            $start_y = floor(($src_info[1] - $water_info[1]) / 2);
            break;
        case 5:
            $start_x = floor(($src_info[0] - $water_info[0]) / 2);
            $start_y = floor(($src_info[1] - $water_info[1]) / 2);
            break;
        case 6:
            $start_x = $src_info[0] - $water_info[0];
            $start_y = floor(($src_info[1] - $water_info[1]) / 2);
            break;
        case 7:
            $start_y = $src_info[1] - $water_info[1];
            break;
        case 8:
            $start_x = floor(($src_info[0] - $water_info[0]) / 2);
            $start_y = $src_info[1] - $water_info[1];
            break;
        case 9:
            $start_x = $src_info[0] - $water_info[0];
            $start_y = $src_info[1] - $water_info[1];
            break;
        case 10:
            // 创建用于平铺的图像资源
            $fun = 'imagecreatefrom' . image_type_to_extension($src_info[2], false);
            $thumb = $fun($src_image);
            // 定义总长度
            $start_x = $src_info[0] - 0;
            $start_y = $src_info[1] - 0;
            $index = 0;
            $ccasd = 0;
            $ccasdy = 0;
            // 循环平铺水印
            for ($x = 0; $x < $start_x; $x) {
                for ($y = 0; $y < $start_y; $y) {
                    if ($x == 0 && $y == 0) {
                        $x = round($ww / 2);
                    }
                    $index++;
                    imagecopy($src, $thumb, 0, 0, $x + $ccasd - $offset_x, $y + $ccasdy, $sourceinfo[0], $sourceinfo[1]);
                    imagecopy($src, $water, 0, 0, 0, 0, $sourceinfo[0], $sourceinfo[1]);
                    imagecopymerge($thumb, $src, $x + $ccasd - $offset_x, $y + $ccasdy, 0, 0, $sourceinfo[0], $sourceinfo[1], $pct);
                    $y += $sourceinfo[1] + $hh;
                }
                $x += $sourceinfo[0] + $ww;
                $index = 0;
            }
            $src_save($thumb, $path_image);
            imagedestroy($src);
            imagedestroy($water);
            return $imagename;
            break;
    }
 
    // 合并水印到源图
    if (imagecopymerge($src, $water, $start_x, $start_y, 0, 0, $water_info[0], $water_info[1], $pct) && $position != 10) {
        $src_save($src, $path_image);
        imagedestroy($src);
        imagedestroy($water);
        return $imagename;
    } else {
        $error = "水印制作失败";
        return false;
    }
}