On 05.08.2008, at 10:03, Wayne Shao wrote:
The imageData method returns NSData*. Is there anyway to know the
image type (e.g, PNG, TIFF, or JPEG) of the data?
besides that what Ken Ferry wrote you may also use (as I do) a low level
way to determine the image type: check for the magic number of image
data.
const unsigned char *bytes = [imageData bytes];
//NSLog( @"%02x %02x %02x %02x ", bytes[0], bytes[1], bytes[2],
bytes[3] );
BOOL isTIFF_BigEndian = (bytes[0]=='M') && (bytes[1]=='M');
BOOL isTIFF_LittleEndian = (bytes[0]=='I') && (bytes[1]=='I');
BOOL isJPEG = (bytes[0]==0xff) && (bytes[1]==0xd8) && (bytes[2]
==0xff);
BOOL isPNG = (bytes[0]==0x89) && (bytes[1]=='P') && (bytes[2]
=='N') && (bytes[3]=='G')
&& (bytes[4]==0x0d) && (bytes[5]==0x0a) && (bytes[6]
==0x1a) && (bytes[7]==0x0a);
BOOL isGIF = (bytes[0]=='G') && (bytes[1]=='I') && (bytes[2]
=='F');
BOOL isPDF = (bytes[0]=='%') && (bytes[1]=='P') && (bytes[2]
=='D')
&& (bytes[3]=='F') && (bytes[4]=='-');
BOOL isBMP = (bytes[0]=='B') && (bytes[1]=='M');
BOOL isICNS = (bytes[0]=='i') && (bytes[1]=='c') && (bytes[2]
=='n') && (bytes[3]=='s');
The Carbon/Cocoa functions and methods do nothing else, they test the
magic number.
Heinrich
--
Heinrich Giesen
[EMAIL PROTECTED]
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