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{%MainUnit ../graphics.pp}
{******************************************************************************
TBitmap
******************************************************************************
*****************************************************************************
This file is part of the Lazarus Component Library (LCL)
See the file COPYING.modifiedLGPL.txt, included in this distribution,
for details about the license.
*****************************************************************************
}
function TestStreamIsBMP(const AStream: TStream): boolean;
var
Signature: array[0..1] of Char;
ReadSize: Integer;
OldPosition: TStreamSeekType;
begin
OldPosition:=AStream.Position;
ReadSize:=AStream.Read(Signature, SizeOf(Signature));
Result:=(ReadSize=2) and (Signature[0]='B') and (Signature[1]='M');
//debugln('TestStreamIsBMP ',DbgStr(Signature[0]),' ',DbgStr(Signature[1]));
AStream.Position:=OldPosition;
end;
type
{ THeaderStream }
THeaderStream = class(TStream)
private
FSource: TStream;
FSourceStart: Int64;
FHeadPos: Integer;
FHeadPtr: PByte;
FHeadSize: Integer;
protected
public
function Read(var Buffer; Count: Longint): Longint; override;
function Seek(const Offset: Int64; Origin: TSeekOrigin): Int64; override;
constructor Create(ASource: TStream; AHeader: Pointer; ASize: Integer);
end;
{ THeaderStream }
constructor THeaderStream.Create(ASource: TStream; AHeader: Pointer; ASize: Integer);
begin
inherited Create;
FSource := ASource;
FSourceStart := ASource.Position;
FHeadPtr := AHeader;
FHeadSize := ASize;
end;
function THeaderStream.Read(var Buffer; Count: Longint): Longint;
var
len: Integer;
buf: PByte;
begin
if Count <= 0 then Exit(0);
if FHeadPos < FHeadSize
then begin
len := Min(FHeadSize - FHeadPos, Count);
Move(FHeadPtr[FHeadPos], Buffer, len);
Dec(Count, len);
Inc(FHeadPos, len);
if Count = 0 then Exit(len);
buf := @Buffer;
Inc(buf, len);
end
else begin
len := 0;
buf := @Buffer;
end;
Result := FSource.Read(buf^, Count) + len;
end;
function THeaderStream.Seek(const Offset: Int64; Origin: TSeekOrigin): Int64;
begin
case Origin of
soBeginning: begin
Result := Offset;
end;
soCurrent: begin
Result := FHeadPos + Offset;
if FHeadPos = FHeadSize
then Inc(Result, FSource.Position);
end;
soEnd: begin
Result := FHeadSize + FSource.Size - FSourceStart + Offset;
end;
end;
if Result < FHeadSize
then begin
FHeadPos := Result;
FSource.Seek(FSourceStart, soBeginning);
end
else begin
FHeadPos := FHeadSize;
FSource.Seek(FSourceStart + Result - FHeadSize, soBeginning);
end;
end;
{ TBitmap }
class function TBitmap.GetFileExtensions: string;
begin
Result:='bmp';
end;
function TBitmap.GetResourceType: TResourceType;
begin
Result := RT_BITMAP;
end;
procedure TBitmap.LoadFromStream(AStream: TStream; ASize: Cardinal);
var
S: THeaderStream;
Header: TBitmapFileHeader;
begin
if AStream is TResourceStream then
begin
if TestStreamIsBMP(AStream) then
{ Handle the special case of an RC_RTDATA resource which contains a
complete, functional TBitmap structure (BitmapFileHeader+BitmapInfoHeader). }
inherited LoadFromStream(AStream, ASize)
else
begin
{ Normal case of an RT_BITMAP resource lacking the BitmapFileHeader }
FillChar(Header, SizeOf(Header), 0);
{ Create a BMP header ordered as it would be on disc, noting that if the CPU
is big-endian this will be the "wrong way round" for numeric operations. }
{$IFNDEF ENDIAN_BIG}
Header.bfType := $4d42;
Header.bfSize := SizeOf(Header) + ASize;
{$ELSE}
Header.bfType := $424d;
Header.bfSize := swap(SizeOf(Header) + ASize);
{$ENDIF}
//Header.bfOffBits := 0; //data follow immediately
S := THeaderStream.Create(AStream, @Header, SizeOf(Header));
try
inherited LoadFromStream(S, SizeOf(Header) + ASize);
finally
S.Free;
end;
end;
end
else
inherited LoadFromStream(AStream, ASize);
end;
class function TBitmap.GetReaderClass: TFPCustomImageReaderClass;
begin
Result := TLazReaderBMP;
end;
class function TBitmap.GetSharedImageClass: TSharedRasterImageClass;
begin
Result := TSharedBitmap;
end;
class function TBitmap.GetWriterClass: TFPCustomImageWriterClass;
begin
Result := TLazWriterBMP;
end;
procedure TBitmap.InitializeReader(AImage: TLazIntfImage; AReader: TFPCustomImageReader);
var
LazReader: TLazReaderBMP absolute AReader;
begin
inherited;
if not (AReader is TLazReaderBMP) then Exit;
// TransparentMode
// tmAuto: use left bottom pixel
// tmFixed: use color
//
// TransparentColor:
// clDefault: use left, bottom pixel color as transparent color (*)
// clNone: load image opaque (*)
// otherwise: use TransparentColor as transparent color
//
// (*) these are Lazarus extensions
if (TransparentMode = tmAuto) or (TransparentColor = clDefault)
then begin
LazReader.MaskMode := lrmmAuto;
end
else begin
if TransparentColor = clNone
then begin
LazReader.MaskMode := lrmmNone;
end
else begin
LazReader.MaskMode := lrmmColor;
LazReader.MaskColor := TColorToFPColor(TransparentColor);
end;
end;
end;
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