Mega Code Archive
Bitmapasvariant
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[with Google search for "delphi image bitmap variant"]
[and you find this on efg's Delphi Graphics site]
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Subject: Re: Help with DIB's
[PUT BITMAP INTO VARIANT AND PULL IT OUT AGAIN]
Date: 12/22/1999
Author: Bob Villiers <100522.66@COMPUSERVE.COM>
Sal,
Take a look at the code below. I have used the function
VarArrayLoadFile to load a bitmap file into a variant array
which is the state I believe you are in with the return from
your ocx. I then load the array into a memory stream, as
a TBitmap has a LoadFromStream method.
In this case I had an array containing the whole bitmap
ie. header and pixel data. If your variant array contains
just the pixel data you will need to do two writes to the
stream, the first to write the bitmap header and the
second (as below) to write the pixel data.
Bob
function VarArrayLoadFile(const FileName: string): Variant;
var
F: file;
Size: Integer;
Data: Pointer;
begin
AssignFile(F, FileName);
Reset(F, 1);
try
Size := FileSize(F);
Result := VarArrayCreate([0, Size - 1], varByte);
Data := VarArrayLock(Result);
try
BlockRead(F, Data^, Size);
finally
VarArrayUnlock(Result);
end;
finally
CloseFile(F);
end;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
vArray: Variant;
iSize: LongInt;
mStream: TMemoryStream;
Bmp: TBitmap;
buffer: Pointer;
begin
{Load bitmap into variant array.}
vArray:= VarArrayLoadFile('CHEMICAL.BMP');
{Calculate size of array}
iSize:= VarArrayHighBound(vArray, 1) - VarArrayLowBound(vArray, 1)+1;
{Get a pointer to the array buffer}
buffer:= VarArrayLock(vArray);
try
{Create stream}
mStream:= TMemoryStream.Create;
try
{Preset stream size}
mStream.SetSize(iSize);
{Write bitmap buffer to the stream}
mStream.Write(buffer^ ,iSize);
{Reset the stream to offset 0}
mStream.Seek(0, 0);
{Create the TBitmap and load the bitmap from the MemoryStream} Bmp := TBitmap.Create;
try
Bmp.LoadFromStream(mStream);
{Draw the bitmap on the form canvas}
Canvas.Draw(10, 10, Bmp);
finally
Bmp.Free;
end;
finally
mStream.Free;
end;
finally
{Remove the lock}
VarArrayUnlock(vArray);
end;
end;
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