이미지(JPG) 사이즈 구하기

이미지(JPG) 사이즈 구하기

 

 

procedure GetJPGSize(const sFile: string; var wWidth, wHeight: Word);

 

function ReadMWord(f: TFileStream): Word;

type

TMotorolaWord = record

case Byte of

0: (Value: Word);

1: (Byte1, Byte2: Byte);

end;

var

MW: TMotorolaWord;

begin

{ It would probably be better to just read these two bytes in normally }

{ and then do a small ASM routine to swap them. But we aren't talking }

{ about reading entire files, so I doubt the performance gain would be }

{ worth the trouble. }

f.read(MW.Byte2, SizeOf(Byte));

f.read(MW.Byte1, SizeOf(Byte));

Result := MW.Value;

end;

 

const

ValidSig: array[0..1] of Byte = ($FF, $D8);

Parameterless = [$01, $D0, $D1, $D2, $D3, $D4, $D5, $D6, $D7];

var

Sig: array[0..1] of byte;

f: TFileStream;

x: integer;

Seg: byte;

Dummy: array[0..15] of byte;

Len: word;

ReadLen: LongInt;

begin

FillChar(Sig, SizeOf(Sig), #0);

f := TFileStream.Create(sFile, fmOpenRead);

try

ReadLen := f.read(Sig[0], SizeOf(Sig));

 

for x := Low(Sig) to High(Sig) do

if Sig[x] <> ValidSig[x] then ReadLen := 0;

if ReadLen > 0 then

begin

ReadLen := f.read(Seg, 1);

while (Seg = $FF) and (ReadLen > 0) do

begin

ReadLen := f.read(Seg, 1);

if Seg <> $FF then

begin

if (Seg = $C0) or (Seg = $C1) then

begin

ReadLen := f.read(Dummy[0], 3); { don't need these bytes }

wHeight := ReadMWord(f);

wWidth := ReadMWord(f);

end

else

begin

if not (Seg in Parameterless) then

begin

Len := ReadMWord(f);

f.Seek(Len - 2, 1);

f.read(Seg, 1);

end

else

Seg := $FF; { Fake it to keep looping. }

end;

end;

end;

end;

finally

f.Free;

end;

end;