位图切割器&位图裁剪器

function HandleSplit(const FileName, DstPath, ImgName: string; 
  UnitW, UnitH: Integer): Boolean;
var
  Handle       : Integer;
  FileHeader   : TBitmapFileHeader;
  BmpInfoHeader: TBitmapInfoHeader;
  Offset       : Integer;
  Mem, DstMem  : TMemoryStream;
  LineLen      : Integer;
  PerBits      : Integer;
  I, J, W, H   : Integer;
  X, Y         : string;

  procedure ReadAreaImgData(L, T, W, H: Integer; Dst: PByte);
  var
    N  : Integer;
    Len: Integer;
  begin
    Len := W * PerBits;  
    for N := T to T + H - 1 do
    begin      
      FileSeek(Handle, Offset + LineLen * N + L * PerBits, 0);
      FileRead(Handle, Dst^, Len);
      Inc(Dst, Len);
    end;
  end;

begin
  Result := False;
  
  Handle := FileOpen(FileName, fmOpenRead or fmShareDenyWrite);
  if Handle < 0 then
    Exit;

  try
    if FileRead(Handle, FileHeader, SizeOf(FileHeader)) <> SizeOf(FileHeader) then
      Exit;
      
    if FileHeader.bfType <> $4D42 then    
      Exit;

    if FileRead(Handle, BmpInfoHeader, SizeOf(BmpInfoHeader)) <> SizeOf(BmpInfoHeader) then
      Exit;

    case BmpInfoHeader.biBitCount of
      16:
        begin
          PerBits := 2;
        end;
      24:
        begin
          PerBits := 3;
        end;
      32:
        begin
          PerBits := 4;
        end
    else
      Exit;
    end;
    
    Offset := SizeOf(FileHeader) + SizeOf(BmpInfoHeader);
    LineLen := (BmpInfoHeader.biWidth * PerBits + 3) div 4 * 4;
    Mem := TMemoryStream.Create;
    DstMem := TMemoryStream.Create;
    
    W :=  BmpInfoHeader.biWidth div UnitW;
    H := BmpInfoHeader.biHeight div UnitH;
    for J := 0 to H - 1 do
    begin
      for I := 0 to W - 1 do
      begin
        X := Format(‘%.3d‘, [I]);
        Y := Format(‘%.3d‘, [H - 1 - J]);
        Mem.Clear;
        Mem.SetSize(UnitW * PerBits * UnitH);
        Mem.Position := 0;
        ReadAreaImgData(I * UnitW, J * UnitH, UnitW, UnitH, Mem.Memory);    
        DstMem.Clear;
        DstMem.Write(FileHeader, SizeOf(FileHeader));
        BmpInfoHeader.biWidth := UnitW;
        BmpInfoHeader.biHeight := UnitH;
        BmpInfoHeader.biSizeImage := 0;
        DstMem.Write(BmpInfoHeader, SizeOf(BmpInfoHeader));
        DstMem.Write(Mem.Memory^, Mem.Size);    
        DstMem.SaveToFile(ImgName + ‘_‘ + Y + ‘_‘ + X + ‘.bmp‘);
      end;
    end;
  
    FreeAndNil(Mem);
    FreeAndNil(DstMem);

    Result := True;
  finally
    FileClose(Handle);
  end;
end;