PHP GD how to draw text over a line

问题

The final output should be like image(HELLO WORLD):

Here is what i am doing:-

$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, $x1, $y1, $txtcol, $font, $txt); // Drawing text over line at line's angle

And current output is like:

Can anybody tell whats the wrong with my code?

THanks

回答1:

Ok, been playing around. Try replacing:

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

With:

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

Output with your values:

Output with other values:

回答2:

2 thoughts, can't test right now.

Where is 0 (x=1, y=0) or (x=0, y=1). It seems your text is off by 90 degrees which usually means that your assuming 0 is directly right, when maybe it's directly up or vice versa.
(rad2deg(atan2($delta_y,$delta_x)) * 180 / M_PI)-360; are you doing double work here? rad2deg converts from radians to degrees. 180 / M_PI is also a conversion from radians to degrees.

回答3:

This is not the exact thing what you may be looking for, but i believe it will help you

$im = imagecreate(400,400); 

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

$size = 20;

$txt = 'DUMMY TEXT';

$font = 'Capriola-Regular.ttf';

/*two points for base line*/

$x1 = 70; $x2 = 170; 

$y1 = 140; $y2 = 240;

/*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,$y2,'0xDD'); //Drawing line
imagettftext($im, $size, -45, $x1, $y1-10, '0xDD', $font, $txt); // Drawing text over line at line's angle

header('Content-Type: image/png');

imagepng($im);
imagedestroy($im);

values are hard coded. Here the angle is given as -45 and for that angle if you want your text to appear above line you have to reduce the value from initial Y position of your line. And you will have to write code to calculate the angle with line's x1,x2y1,y2

来源：https://stackoverflow.com/questions/14894049/php-gd-how-to-draw-text-over-a-line

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