PHP uses GD library to generate images in BMP format (imagebmp)

/ **

* Create bmp format picture
*
* @author: legend
* @description: create Bitmap-File with GD library
* @version: 0.1
*
* @param resource $ im image resource
* @param string $ filename If you want to save as a file, please specify the file name, if it is empty, it will be directly output in the browser
* @param integer $ bit image quality (1, 4, 8, 16, 24, 32 bits)
* @param integer $ compression compression method, 0 is not compressed, 1 is compressed using RLE8 compression algorithm
*
* @return integer
* /
function imagebmp (& $ im, $ filename = ”, $ bit = 8, $ compression = 0)
{
if (! in_array ($ bit, array (1, 4, 8, 16, 24, 32)))
{
$ bit = 8;
}
else if ($ bit == 32) // todo: 32 bit
{
$ bit = 24;
}
$ bits = pow (2, $ bit);

// adjust the palette

imagetruecolortopalette ($ im, true, $ bits);
$ width = imagesx ($ im);
$ height = imagesy ($ im);
$ colors_num = imagecolorstotal ($ im);
if ($ bit <= 8)

{
// color index
$ rgb_quad = ”;
for ($ i = 0; $ i <$ colors_num; $ i ++)
{
$ colors = imagecolorsforindex ($ im, $ i);
$ rgb_quad. = chr ($ colors ['blue']). chr ($ colors ['green']). chr ($ colors ['red']). "\ 0 ″;
}
// bitmap data

$ bmp_data = ”;
// uncompressed

if ($ compression == 0 || $ bit <8)
{
if (! in_array ($ bit, array (1, 4, 8)))
{
$ bit = 8;
}
$ compression = 0;

// The number of bytes in each line must be a multiple of 4, which is complemented.

$ extra = ”;
$ padding = 4 – ceil ($ width / (8 / $ bit))% 4;
if ($ padding% 4! = 0)
{
$ extra = str_repeat (“\ 0 ″, $ padding);
}
for ($ j = $ height – 1; $ j> = 0; $ j-)

{
$ i = 0;
while ($ i <$ width)
{
$ bin = 0;
$ limit = $ width – $ i <8 / $ bit? (8 / $ bit-$ width + $ i) * $ bit: 0;
for ($ k = 8 – $ bit; $ k> = $ limit; $ k-= $ bit)

{
$ index = imagecolorat ($ im, $ i, $ j);
$ bin | = $ index << $ k;
$ i ++;
}
$ bmp_data. = chr ($ bin);

}
$ bmp_data. = $ extra;

}
}
// RLE8 compression
else if ($ compression == 1 && $ bit == 8)
{
for ($ j = $ height – 1; $ j> = 0; $ j-)
{
$ last_index = "\ 0 ″;
$ same_num = 0;
for ($ i = 0; $ i <= $ width; $ i ++)
{
$ index = imagecolorat ($ im, $ i, $ j);
if ($ index! == $ last_index || $ same_num> 255)
{
if ($ same_num! = 0)
{
$ bmp_data. = chr ($ same_num). chr ($ last_index);
}
$ last_index = $ index;

$ same_num = 1;
}
else
{
$ same_num ++;
}
}
$ bmp_data. = "\ 0 \ 0 ″;

}
$ bmp_data. = "\ 0 \ 1 ″;

}
$ size_quad = strlen ($ rgb_quad);

$ size_data = strlen ($ bmp_data);
}
else
{
// The number of bytes in each line must be a multiple of 4, which is complemented.
$ extra = ”;
$ padding = 4 – ($ width * ($ bit / 8))% 4;
if ($ padding% 4! = 0)
{
$ extra = str_repeat (“\ 0 ″, $ padding);
}
// bitmap data

$ bmp_data = ”;
for ($ j = $ height – 1; $ j> = 0; $ j-)

{
for ($ i = 0; $ i <$ width; $ i ++)
{
$ index = imagecolorat ($ im, $ i, $ j);
$ colors = imagecolorsforindex ($ im, $ index);
if ($ bit == 16)

{
$ bin = 0 << $ bit;
$ bin | = ($ colors ['red'] >> 3) << 10;

$ bin | = ($ colors ['green'] >> 3) << 5;
$ bin | = $ colors ['blue'] >> 3;
$ bmp_data. = pack (“v”, $ bin);

}
else
{
$ bmp_data. = pack (“c *”, $ colors ['blue'], $ colors ['green'], $ colors ['red']);
}
// todo: 32bit;

}
$ bmp_data. = $ extra;

}
$ size_quad = 0;

$ size_data = strlen ($ bmp_data);
$ colors_num = 0;
}
// bitmap file header

$ file_header = “BM”. pack (“V3 ″, 54 + $ size_quad + $ size_data, 0, 54 + $ size_quad);
// bitmap information header

$ info_header = pack (“V3v2V *”, 0 × 28, $ width, $ height, 1, $ bit, $ compression, $ size_data, 0, 0, $ colors_num, 0);
// write to file

if ($ filename! = ”)
{
$ fp = fopen (“test.bmp”, “wb”);
fwrite ($ fp, $ file_header);

fwrite ($ fp, $ info_header);
fwrite ($ fp, $ rgb_quad);
fwrite ($ fp, $ bmp_data);
fclose ($ fp);
return 1;

}
// browser output

header ("Content-Type: image / bmp");
echo $ file_header. $ info_header;
echo $ rgb_quad;
echo $ bmp_data;
return 1;

}
?>