【标题】：ASP adodb.stream 取 .png 图片完整文件头信息 By shawl.qiu
【关键字】：ASP,adodb.stream,.png,By,shawl.qiu
【来源】：http://blog.csdn.net/btbtd/archive/2006/09/17/1232943.aspx

ASP adodb.stream 取 .png 图片完整文件头信息 By shawl.qiu

摘要:
主要目的为取 .png文件的高宽度信息, 使用ASP完成(不用外建组件).
进一步了解请查看相关文章.

作用:
本文使用 ASP 的内置组件 adodb.stream 取得 .png 的头部信息, 包括高宽度信息.

相关文章:
1. ASP adodb.stream 取 Win32 .bmp 图片完整文件头信息 By shawl.qiu
URL: http://blog.csdn.net/btbtd/archive/2006/09/16/1228908.aspx

2. ASP adodb.stream 取 .gif 图片完整文件头&描述信息 By shawl.qiu
URL: http://blog.csdn.net/btbtd/archive/2006/09/17/1232530.aspx

目录:
1. 主内容: 完整例子
2. 参考文献
3. 预览

附: 测试图片

shawl.qiu
2006-09-17
http://blog.csdn.net/btbtd/

1. 主内容: 完整例子

linenum

<%
dim file:file=server.MapPath("a.png")
dim temp
dim stm
set stm=createObject("adodb.stream")
with stm
.type = 1
.open
.loadFromFile file
temp=.read
.close
end with
set stm=nothing
response.write "png file info: "
response.write " #2-4/3 Header Signature: "&binToStr(midB(temp,2,3))
response.write " #12-16/4 First chunk(IHDR): "&binToStr(midB(temp,12,5))
response.write " #17-20/4 Width: "&binToNumPng(midB(temp,17,4))
response.write " #21-24/4 Height: "&binToNumPng(midB(temp,21,4))
response.write " #25-25/1 Bit depth: "&binToNumPng(midB(temp,25,1))
response.write " #26-26/1 ColorType: "&binToNumPng(midB(temp,26,1))
response.write " #27-27/1 Compression method: "&binToNumPng(midB(temp,17,1))
response.write " #28-28/1 Filter method: "&binToNumPng(midB(temp,28,1))
response.write " #29-29/1 Interlace method: "&binToNumPng(midB(temp,29,1))
private function binToNumPng(bin)
'二进制转为 Numeric (png)
dim i:binToNumPng=0
for i=1 to lenB(bin)
binToNumPng=binToNumPng*256+ascB(midB(bin,i,1))
next 'shawl.qiu'
end function
private function binToStr(bin)
'二进制转为 string (bmp|gif|png)
dim i, iByt, sByt, bLen:bLen=lenB(bin)
for i=1 to bLen
sByt=midB(bin,i,1):iByt=ascB(sByt)
if iByt<128 then
binToStr=binToStr&chr(iByt)
else:i=i+1
if i<=bLen then binToStr=binToStr&chr(ascW(sByt&sByt))
end if
next 'shawl.qiu'
end function
%>

2. 参考文献
PNG File Format Summary
URL: http://www.fileformat.info/format/png/

3. 预览

png file info:

#2-4/3 Header Signature: PNG
#12-16/4 First chunk(IHDR): IHDR
#17-20/4 Width: 120
#21-24/4 Height: 146
#25-25/1 Bit depth: 8
#26-26/1 ColorType: 3
#27-27/1 Compression method: 0
#28-28/1 Filter method: 0
#29-29/1 Interlace method: 0

附: 测试图片