PHP imitation GD generated BMP image

PHP imitation GD generated BMP image Function Imagebmp (& $im, $filename = ", $bit = 8, $compression = 0) { if (!in_array ($bit, Array (1, 4, 8, 16, 24, 32))) { $bit = 8; } else if ($bit = = +)//todo:32 bit { $bit = 24; } $bits = POW (2, $bit); Adjust Palette Imagetruecolortopalette ($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 ']). "The"; } Bitmap data $bmp _data = "; Non-compressed if ($compression = = 0 | | $bit < 8) { if (!in_array ($bit, Array (1, 4, 8))) { $bit = 8; } $compression = 0; The number of bytes per line must be a multiple of 4, padded. $extra = "; $padding = 4-ceil ($width/(8/$bit))% 4; if ($padding% 4! = 0) { $extra = Str_repeat ("n", $padding); } for ($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 = "n"; $same _num = 0; for ($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 per line must be a multiple of 4, padded. $extra = "; $padding = 4-($width * ($bit/8))% 4; if ($padding% 4! = 0) { $extra = Str_repeat ("n", $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", si + $size _quad + $size _data, 0, + $size _quad); Bitmap Information Header $info _header = Pack ("v3v2v*", 0x28, $width, $height, 1, $bit, $compression, $size _data, 0, 0, $colors _num, 0); Write file if ($filename! = ") { $fp = fopen ($filename, "WB"); Fwrite ($fp, $file _header); Fwrite ($fp, $info _header); Fwrite ($fp, $rgb _quad); Fwrite ($fp, $bmp _data); Fclose ($FP); return true; } Browser output Header ("Content-type:image/bmp"); Echo $file _header. $info _header; echo $rgb _quad; echo $bmp _data; return true; } Copy Code

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