PHP / GD图像-不可见或未绘制的线

Question

我在画布上画了几个盒子，但是图像线似乎有问题。虚线似乎是看不见的，除了线不是水平的情况。有什么不对的想法吗？

示例代码

$width = 204;
$height = 317;

$canvas = imagecreate($width, $height);

$white = imagecolorallocate($canvas, 255, 2555, 255);
$black = imagecolorallocate($canvas, 0, 0, 0);

$topLeft     = 2;
$topRight    = 2;

$bottomLeft  = $width-2;
$bottomRight = $height-2;

imagesetthickness($canvas, 1);

// parallel line, solid
imageline($canvas, 0, 101, 204, 101, $black);

// parallel line, should be dashed, fail
imagedashedline($canvas, 0, 121, 204, 121, $black);

// parallel line should be dashed, works
imagedashedline($canvas, 0, 0, 204, 305, $black);

imagejpeg($canvas,'dashes.jpg');
imagedestroy($canvas)

输出

​

​

Answer 1

参见关于imagedashedline()的评论。另外，它是不推荐的，但是您可以使用imagesetstyle()和imageline()的组合。