php使用GD庫生成bmp格式的圖片(imagebmp)

2020-03-22 18:41:36

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/**
* 創(chuàng)建bmp格式圖片
*
* @author: legend
* @description: create Bitmap-File with GD library
* @version: 0.1
*
* @param resource $im 圖像資源
* @param string $filename 如果要另存為文件，請(qǐng)指定文件名，為空則直接在瀏覽器輸出
* @param integer $bit 圖像質(zhì)量(1、4、8、16、24、32位)
* @param integer $compression 壓縮方式，0為不壓縮，1使用RLE8壓縮算法進(jìn)行壓縮
*
* @return integer
*/
function imagebmp(&$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, $bit);
// 調(diào)整調(diào)色板
imagetruecolortopalette($im, true, $bits);
$width = imagesx($im);
$height = imagesy($im);
$colors_num = imagecolorstotal($im);
if ($bit <= 8)
{
// 顏色索引
$rgb_quad = ”;
for ($i = 0; $i < $colors_num; $i ++)
{
$colors = imagecolorsforindex($im, $i);
$rgb_quad .= chr($colors['blue']) . chr($colors['green']) . chr($colors['red']) . “/0″;
}
// 位圖數(shù)據(jù)
$bmp_data = ”;
// 非壓縮
if ($compression == 0 || $bit < 8)
{
if (!in_array($bit, array(1, 4, 8)))
{
$bit = 8;
}
$compression = 0;
// 每行字節(jié)數(shù)必須為4的倍數(shù)，補(bǔ)齊。
$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 .= $extra;
}
}
// RLE8 壓縮
else if ($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
{
// 每行字節(jié)數(shù)必須為4的倍數(shù)，補(bǔ)齊。
$extra = ”;
$padding = 4 – ($width * ($bit / 8)) % 4;
if ($padding % 4 != 0)
{
$extra = str_repeat(“/0″, $padding);
}
// 位圖數(shù)據(jù)
$bmp_data = ”;
for ($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;
}
// 位圖文件頭
$file_header = “BM” . pack(“V3″, 54 + $size_quad + $size_data, 0, 54 + $size_quad);
// 位圖信息頭
$info_header = pack(“V3v2V*”, 0×28, $width, $height, 1, $bit, $compression, $size_data, 0, 0, $colors_num, 0);
// 寫入文件
if ($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;
}
// 瀏覽器輸出
header(“Content-Type: image/bmp”);
echo $file_header . $info_header;
echo $rgb_quad;
echo $bmp_data;
return 1;
}
?>