PHP GD如何通过一行绘制文本

这是我在做什么： –

$im = imagecreate(400,400); 

$txtcol = imagecolorallocate($im,0xFF,0x00,0x00);

$size = 20;

$txt = 'DUMMY TEXT';

$font = './font/Capriola-Regular.ttf';

/*two points for base line*/

$x1 = 50; $x2 = 300; 

$y1 = 150; $y2 = 170;

/*bof finding line angle*/

$delta_x = $x2-$x1;

$delta_y = $y2-$y1;

$texangle = (rad2deg(atan2($delta_y,$delta_x)) * 180 / M_PI)-360;

/*eof finding the line angle*/


imageline($im,$x1,$y1,$x2,$y2,$txtcol); //Drawing line

imagettftext($im,$size,$texangle,$txtcol,$font,$txt); // Drawing text over line at line's angle

目前的输出如下：

任何人都可以告诉我的代码有什么问题吗？

谢谢