Mega Code Archive
Get width and height of a PNG image file
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Title: Get width and height of a PNG image file
function ReadMWord(f: TFileStream): Word;
type
TMotorolaWord = record
case Byte of
0: (Value: Word);
1: (Byte1, Byte2: Byte);
end;
var
MW: TMotorolaWord;
begin
f.read(MW.Byte2, SizeOf(Byte));
f.read(MW.Byte1, SizeOf(Byte));
Result := MW.Value;
end;
procedure GetPNGSize(const sFile: string; var wWidth, wHeight: Word);
type
TPNGSig = array[0..7] of Byte;
const
ValidSig: TPNGSig = (137,80,78,71,13,10,26,10);
var
Sig: TPNGSig;
f: tFileStream;
x: integer;
begin
FillChar(Sig, SizeOf(Sig), #0);
f := TFileStream.Create(sFile, fmOpenRead);
try
f.read(Sig[0], SizeOf(Sig));
for x := Low(Sig) to High(Sig) do
if Sig[x] ValidSig[x] then Exit;
f.Seek(18, 0);
wWidth := ReadMWord(f);
f.Seek(22, 0);
wHeight := ReadMWord(f);
finally
f.Free;
end;
end;
Example usage:
var width,height:word;
begin
GetPNGSize(filename,width, height);
end;
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