Use the GD library to generate images with shadow text, gd shadow_PHP tutorial

Use the GD library to generate images with shadow text, gd shadow

Recently, the GD library was used to generate images for WeChat public accounts, and I studied the generation of text shadow effects in the GD library At the same time, I also discovered the power of the GD library.

GD library is an extension library for PHP to process graphics. The GD library provides a series of APIs for processing pictures. You can use the GD library to process pictures or generate pictures. On websites, the GD library is usually used to generate thumbnails, add watermarks to images, generate Chinese character verification codes, or generate reports on website data.
The installation of the GD library is available online, and many virtual spaces now support it, so I won’t go into details here. Below, I will introduce how to use the GD library through examples of my actual application code and related comments.

Original picture:

Generate renderings:

The code is as follows:

$str="北京";
$str2= "空气质量：轻度污染";
// 通过图片生成一个对象$im
$im = imagecreatefromjpeg("images/3.jpg");
//载入字体zt.ttf
$fnt = "zt.ttf";
//创建颜色，用于文字字体的白和阴影的黑
$white=imagecolorallocate($im,222,229,207);
$black=imagecolorallocate($im,50,50,50);
//创建关于相对图片位置的函数，方便调用
$top=100;
$left=60;
$top2=170;
//在图片中添加文字，imagettftext (image,size,angle, x, y,color,fontfile,text)
imagettftext($im,41, 0, $left+1, $top+1, $black, $fnt, $str);
imagettftext($im,41, 0, $left, $top, $white, $fnt, $str);
imagettftext($im,43, 0, $left+1,$top2+1 , $black, $fnt, $str2);
imagettftext($im,43, 0, $left,$top2, $white, $fnt, $str2);
//将$im输出
ImageJpeg($im);
//销毁$im对象
ImageDestroy($im);

The following will explain in detail:

imagettftext (image,size,angle, x, y,color,fontfile,text)
imagettftext() draws the string text onto the image represented by image, starting from the coordinates x, y (the upper left corner is 0, 0), the angle is angle, the color is color, and the TrueType font file specified by fontfile is used.

The coordinates represented by x,y define the basic point of the first character approximately at the lower left corner of the character.

angle is expressed in degrees, with 0 degrees meaning the text is read from left to right and higher values ​​meaning counter-clockwise (i.e. a value of 90 means the text is read from bottom to top).

fontfile is the file name of the TrueType font you want to use.

text is a text string that can contain UTF-8 character sequences.

color is the index value of the color.

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