在线编辑二维码并发送到热敏打印机打印

使用到的 js 插件：

图片要转成BMP格式。转换图片到BMP的类：

2. /**
3. * class jpg, gif, png =========> BMP
4. *
5. * { Description :-
6. * class that resize and convert jpg, gif or png to bmp
7. * }
8. * for more info contact with me (mahabub1212@yahoo.com)
9. * you can modify or use or redistribute this class.
10. */
11. class ToBmp{
13. // new image width
14. var $new_width;
16. // new image height
17. var $new_height;
19. // image resources
20. var $image_resource;
22. function image_info($source_image){
23. $img_info = getimagesize($source_image);
25. switch ($img_info['mime']){
26. case "image/jpeg": { $this->image_resource = imagecreatefromjpeg ($source_image); break; }
27. case "image/gif": { $this->image_resource = imagecreatefromgif ($source_image); break; }
28. case "image/png": { $this->image_resource = imagecreatefrompng ($source_image); break; }
29. default: {die("图片错误");}
30. }
31. }
34. public function imagebmp($file_path = ''){
36. if(!$this->image_resource) die("图片错误");
37. $picture_width = imagesx($this->image_resource);
38. $picture_height = imagesy($this->image_resource);
41. if(!imageistruecolor($this->image_resource)){
42. $tmp_img_reource = imagecreatetruecolor($picture_width,$picture_height);
43. imagecopy($tmp_img_reource,$this->image_resource, 0, 0, 0, 0, $picture_width, $picture_height);
44. imagedestroy($this->image_resource);
45. $this->image_resource = $tmp_img_reource;
47. }
50. if((int) $this->new_width >0 && (int) $this->new_height > 0){
52. $image_resized = imagecreatetruecolor($this->new_width, $this->new_height);
53. imagecopyresampled($image_resized,$this->image_resource,0,0,0,0,$this->new_width,$this->new_height,$picture_width,$picture_height);
54. imagedestroy($this->image_resource);
55. $this->image_resource = $image_resized;
57. }
59. $result = '';
61. $biBPLine = ((int) $this->new_width >0 &&(int)$this->new_height > 0) ? $this->new_width * 3 : $picture_width * 3;
62. $biStride = ($biBPLine + 3) & ~3;
63. $biSizeImage = ((int) $this->new_width >0 &&(int)$this->new_height > 0) ? $biStride * $this->new_height : $biStride * $picture_height;
64. $bfOffBits = 54;
65. $bfSize = $bfOffBits + $biSizeImage;
67. $result .= substr('BM', 0, 2);
68. $result .= pack ('VvvV', $bfSize, 0, 0, $bfOffBits);
69. $result .= ((int) $this->new_width >0 &&(int)$this->new_height > 0) ? pack ('VVVvvVVVVVV', 40, $this->new_width, $this->new_height, 1, 24, 0, $biSizeImage, 0, 0, 0, 0) : pack ('VVVvvVVVVVV', 40, $picture_width, $picture_height, 1, 24, 0, $biSizeImage, 0, 0, 0, 0);
71. $numpad = $biStride - $biBPLine;
73. $h = ((int) $this->new_width >0 &&(int)$this->new_height > 0) ? $this->new_height : $picture_height;
74. $w = ((int) $this->new_width >0 &&(int)$this->new_height > 0) ? $this->new_width : $picture_width;
76. for ($y = $h - 1; $y >= 0; --$y) {
77. for ($x = 0; $x < $w; ++$x) {
78. $col = imagecolorat ($this->image_resource, $x, $y);
79. $result .= substr(pack ('V', $col), 0, 3);
80. }
81. for ($i = 0; $i < $numpad; ++$i) {
82. $result .= pack ('C', 0);
83. }
84. }
87. if($file_path == ''){
89. header("Content-type: image/bmp");
90. echo $result;
91. } else {
93. $fp = fopen($file_path,"wb");
94. fwrite($fp,$result);
95. fclose($fp);
96. //=============
97. }
100. return ;
103. }
104. }

使用方法

1. $ToBMP = new ToBmp();
2. $ToBMP->image_info($path_to_img);
3. $ToBMP->new_width = 255;
4. $ToBMP->new_height = 255;
5. $output_path = realpath(PATH.'test.bmp');
6. $ToBMP->imagebmp($output_path);

BMP格式根据文件头信息不同数据组成结构也不同

我的是24位BMP，去除头文件54个字节后，每三个字节(RGB)表示一个点。

合并RGB（三字节合并为一字节）后二值化像素点(得到 1bit ，即该点是黑或白。之所以要二值化是因为我的热敏打印机打印黑白不打印彩色)。

每 8bit 拼接成1字节后用 '\xx' 的16进制形式表示。数据根据打印机给的接口发送给打印机就可以打印了。

1.unpack的使用

1. $content = file_get_contents($path_to_img);
2. $content = unpack("H*", $content); //获得图片数据的16进制表示

2.

‘\xFE’ 表示的是4个字符

“\xFE” 表示的是1个字符(即该16进制数字对应的ascii码字符)

单引号的可使用 chr('0xFE') 进行转换