我想使用GD库在PHP中使用图像绘制厚度线。我在这个页面中找到了一些解决方案PHP: imageline - Manual但是当行的(x,y)位置改变时,它们似乎都没有正常工作。
我在页面中找到了3个功能
function dickelinie($img, $start_x, $start_y, $end_x, $end_y, $color, $thickness)
{
$angle = (atan2(($start_y - $end_y), ($end_x - $start_x)));
$dist_x = $thickness * (sin($angle));
$dist_y = $thickness * (cos($angle));
$p1x = ceil(($start_x + $dist_x));
$p1y = ceil(($start_y + $dist_y));
$p2x = ceil(($end_x + $dist_x));
$p2y = ceil(($end_y + $dist_y));
$p3x = ceil(($end_x - $dist_x));
$p3y = ceil(($end_y - $dist_y));
$p4x = ceil(($start_x - $dist_x));
$p4y = ceil(($start_y - $dist_y));
$array = array(0 => $p1x, $p1y, $p2x, $p2y, $p3x, $p3y, $p4x, $p4y);
imagefilledpolygon ($img, $array, (count($array) / 2), $color);
}
function imagelinethick($image, $x1, $y1, $x2, $y2, $color, $thick = 1)
{
if ($thick == 1)
{
return imageline($image, $x1, $y1, $x2, $y2, $color);
}
$t = $thick / 2 - 0.5;
if ($x1 == $x2 || $y1 == $y2)
{
return imagefilledrectangle($image, round(min($x1, $x2) - $t), round(min($y1, $y2) - $t), round(max($x1, $x2) + $t), round(max($y1, $y2) + $t), $color);
}
$k = ($y2 - $y1) / ($x2 - $x1);
$a = $t / sqrt(1 + pow($k, 2));
$points = array(
round($x1 - (1+$k)*$a), round($y1 + (1-$k)*$a),
round($x1 - (1-$k)*$a), round($y1 - (1+$k)*$a),
round($x2 + (1+$k)*$a), round($y2 - (1-$k)*$a),
round($x2 + (1-$k)*$a), round($y2 + (1+$k)*$a),
);
imagefilledpolygon($image, $points, 4, $color);
return imagepolygon($image, $points, 4, $color);
}
function imagelinethick1($image, $x1, $y1, $x2, $y2, $color, $thick = 1)
{
imagesetthickness($image, $thick);
imageline($image, $x1, $y1, $x2, $y2, $color);
}
我的测试用例是
header("Content-Type: image/png");
$image = @imagecreatetruecolor(500, 500) or die("Cannot initialize new GD image stream");
$color = imagecolorallocate($image, 255, 255, 255);
# Line thickness equals to 18 pixels
$thickness = 18;
# OK
dickelinie($image, 0, 0, 0, 500, $color, $thickness);
# Wrong: The thickness of the line is doubled
dickelinie($image, 200, 0, 200, 500, $color, $thickness);
# Wrong: The thickness of the line is halved
imagelinethick($image, 0, 0, 0, 500, $color, $thickness);
# OK
imagelinethick($image, 200, 0, 200, 500, $color, $thickness);
# Wrong: The thickness of the line is halved
imagelinethick1($image, 0, 0, 0, 500, $color, $thickness);
# OK
imagelinethick1($image, 200, 0, 200, 500, $color, $thickness);
imagepng($image);
imagedestroy($image);
有人可以告诉我有什么问题吗?
答案 0 :(得分:0)
php.net的imageline
示例#1是“画一条粗线”。它建议使用imagesetthickness
或以下代码:
<?php
function imagelinethick($image, $x1, $y1, $x2, $y2, $color, $thick = 1)
{
/* this way it works well only for orthogonal lines
imagesetthickness($image, $thick);
return imageline($image, $x1, $y1, $x2, $y2, $color);
*/
if ($thick == 1) {
return imageline($image, $x1, $y1, $x2, $y2, $color);
}
$t = $thick / 2 - 0.5;
if ($x1 == $x2 || $y1 == $y2) {
return imagefilledrectangle($image, round(min($x1, $x2) - $t), round(min($y1, $y2) - $t), round(max($x1, $x2) + $t), round(max($y1, $y2) + $t), $color);
}
$k = ($y2 - $y1) / ($x2 - $x1); //y = kx + q
$a = $t / sqrt(1 + pow($k, 2));
$points = array(
round($x1 - (1+$k)*$a), round($y1 + (1-$k)*$a),
round($x1 - (1-$k)*$a), round($y1 - (1+$k)*$a),
round($x2 + (1+$k)*$a), round($y2 - (1-$k)*$a),
round($x2 + (1-$k)*$a), round($y2 + (1+$k)*$a),
);
imagefilledpolygon($image, $points, 4, $color);
return imagepolygon($image, $points, 4, $color);
}
?>
答案 1 :(得分:0)
您的一些测试用例是错误的。每个用x = 0渲染的测试用例都将被切成两半,因为例程将新的粗线放在给定的xy坐标上。因此,渲染线的一半在位图之外渲染并丢失。
鉴于您的测试用例存在一点缺陷,我们可以看到“dickelinie”方法总是使预期厚度加倍。
我仍然使用“dickelinie”方法渲染简单的模拟时钟,因为它可以满足我的需求。我只是将它的厚度减半,以确保它有效。我还在“dickelinie”方法的末尾添加了以下代码,以确保在被告知为:
时,生成的行被呈现为消除锯齿:return imagepolygon($img, $array, (count($array) / 2), $color);
如果你需要以不同的角度渲染线条,你会想要这个。
答案 2 :(得分:0)
这不是解决问题的最快方法,但我在我的项目中使用此功能:
function thickline( $img, $x1, $y1, $x2, $y2, $color, $thickness ) {
$radius = $thickness * .5;
$vx = $x2 - $x1;
$vy = $y2 - $y1;
$steps = ceil( .5 + max( abs($vx), abs($vy) ) );
$vx /= $steps;
$vy /= $steps;
$x = $x1;
$y = $y1;
while( $steps --> 0 ) {
imagefilledellipse( $img, $x, $y, $radius, $radius, $color );
$x += $vx;
$y += $vy;
}
}
这个想法是在一条线的每个点上绘制一个圆圈。