php 生成透明png图片
getDatePic();
function getDatePic()
{
//4.添加文字水印
$font_size = 90;
$font_angle = 0;
$font_x = 0;
$font_y = 90 - 90/6;
$font_file = 'font/ygyxsziti2.0.ttf'; //字体文件路径
$text = 'centPHP' . date('H:i:s');
//取得使用 TrueType 字体的文本的范围
$font_arr = imagettfbbox($font_size, $font_angle, $font_file, $text);
$font_width = abs($font_arr[4] - $font_arr[6]);
$font_height = abs($font_arr[1] - $font_arr[7]);
$dst_im = imagecreatetruecolor($font_width, $font_height);
$fill_color = imagecolorallocatealpha($dst_im, 255, 255, 255, 127);
//imagealphablending($dst_im , false);//关闭混合模式，以便透明颜色能覆盖原画布
imagefill($dst_im, 0, 0, $fill_color);
//3.生成文字颜色
$font_color = imagecolorallocatealpha($dst_im, 255, 0, 0, 60);
imagefttext($dst_im, $font_size, $font_angle, $font_x, $font_y, $font_color, $font_file, $text);
$font_color = imagecolorallocatealpha($dst_im, 0, 255, 0, 60);
imagefttext($dst_im, $font_size, $font_angle, 15, $font_y, $font_color, $font_file, $text);
//5.生成图片
//header("content-type:image/png");
//imagepng($dst_im);
$file = date('Ymd_His') . '.png';
imagesavealpha($dst_im, true);//设置保存PNG时保留透明通道信息
imagepng($dst_im, $file);
}
