一个屏幕广播的例子中客户端为什么屏幕不能完整(100分)

附原码：主机：unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ExtCtrls, IdBaseComponent, IdComponent, IdUDPBase,IdSocketHandle,
IdUDPClient,Jpeg, IdUDPServer,IdException;

const
Table: array[0..255] of DWORD =
($00000000, $77073096, $EE0E612C, $990951BA,
$076DC419, $706AF48F, $E963A535, $9E6495A3,
$0EDB8832, $79DCB8A4, $E0D5E91E, $97D2D988,
$09B64C2B, $7EB17CBD, $E7B82D07, $90BF1D91,
$1DB71064, $6AB020F2, $F3B97148, $84BE41DE,
$1ADAD47D, $6DDDE4EB, $F4D4B551, $83D385C7,
$136C9856, $646BA8C0, $FD62F97A, $8A65C9EC,
$14015C4F, $63066CD9, $FA0F3D63, $8D080DF5,
$3B6E20C8, $4C69105E, $D56041E4, $A2677172,
$3C03E4D1, $4B04D447, $D20D85FD, $A50AB56B,
$35B5A8FA, $42B2986C, $DBBBC9D6, $ACBCF940,
$32D86CE3, $45DF5C75, $DCD60DCF, $ABD13D59,
$26D930AC, $51DE003A, $C8D75180, $BFD06116,
$21B4F4B5, $56B3C423, $CFBA9599, $B8BDA50F,
$2802B89E, $5F058808, $C60CD9B2, $B10BE924,
$2F6F7C87, $58684C11, $C1611DAB, $B6662D3D,

$76DC4190, $01DB7106, $98D220BC, $EFD5102A,
$71B18589, $06B6B51F, $9FBFE4A5, $E8B8D433,
$7807C9A2, $0F00F934, $9609A88E, $E10E9818,
$7F6A0DBB, $086D3D2D, $91646C97, $E6635C01,
$6B6B51F4, $1C6C6162, $856530D8, $F262004E,
$6C0695ED, $1B01A57B, $8208F4C1, $F50FC457,
$65B0D9C6, $12B7E950, $8BBEB8EA, $FCB9887C,
$62DD1DDF, $15DA2D49, $8CD37CF3, $FBD44C65,
$4DB26158, $3AB551CE, $A3BC0074, $D4BB30E2,
$4ADFA541, $3DD895D7, $A4D1C46D, $D3D6F4FB,
$4369E96A, $346ED9FC, $AD678846, $DA60B8D0,
$44042D73, $33031DE5, $AA0A4C5F, $DD0D7CC9,
$5005713C, $270241AA, $BE0B1010, $C90C2086,
$5768B525, $206F85B3, $B966D409, $CE61E49F,
$5EDEF90E, $29D9C998, $B0D09822, $C7D7A8B4,
$59B33D17, $2EB40D81, $B7BD5C3B, $C0BA6CAD,

$EDB88320, $9ABFB3B6, $03B6E20C, $74B1D29A,
$EAD54739, $9DD277AF, $04DB2615, $73DC1683,
$E3630B12, $94643B84, $0D6D6A3E, $7A6A5AA8,
$E40ECF0B, $9309FF9D, $0A00AE27, $7D079EB1,
$F00F9344, $8708A3D2, $1E01F268, $6906C2FE,
$F762575D, $806567CB, $196C3671, $6E6B06E7,
$FED41B76, $89D32BE0, $10DA7A5A, $67DD4ACC,
$F9B9DF6F, $8EBEEFF9, $17B7BE43, $60B08ED5,
$D6D6A3E8, $A1D1937E, $38D8C2C4, $4FDFF252,
$D1BB67F1, $A6BC5767, $3FB506DD, $48B2364B,
$D80D2BDA, $AF0A1B4C, $36034AF6, $41047A60,
$DF60EFC3, $A867DF55, $316E8EEF, $4669BE79,
$CB61B38C, $BC66831A, $256FD2A0, $5268E236,
$CC0C7795, $BB0B4703, $220216B9, $5505262F,
$C5BA3BBE, $B2BD0B28, $2BB45A92, $5CB36A04,
$C2D7FFA7, $B5D0CF31, $2CD99E8B, $5BDEAE1D,

$9B64C2B0, $EC63F226, $756AA39C, $026D930A,
$9C0906A9, $EB0E363F, $72076785, $05005713,
$95BF4A82, $E2B87A14, $7BB12BAE, $0CB61B38,
$92D28E9B, $E5D5BE0D, $7CDCEFB7, $0BDBDF21,
$86D3D2D4, $F1D4E242, $68DDB3F8, $1FDA836E,
$81BE16CD, $F6B9265B, $6FB077E1, $18B74777,
$88085AE6, $FF0F6A70, $66063BCA, $11010B5C,
$8F659EFF, $F862AE69, $616BFFD3, $166CCF45,
$A00AE278, $D70DD2EE, $4E048354, $3903B3C2,
$A7672661, $D06016F7, $4969474D, $3E6E77DB,
$AED16A4A, $D9D65ADC, $40DF0B66, $37D83BF0,
$A9BCAE53, $DEBB9EC5, $47B2CF7F, $30B5FFE9,
$BDBDF21C, $CABAC28A, $53B39330, $24B4A3A6,
$BAD03605, $CDD70693, $54DE5729, $23D967BF,
$B3667A2E, $C4614AB8, $5D681B02, $2A6F2B94,
$B40BBE37, $C30C8EA1, $5A05DF1B, $2D02EF8D);


type
TForm1 = class(TForm)
Button1: TButton;
Edit1: TEdit;
procedure FormCreate(Sender: TObject);
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
PriorCRC,NewCRC: array[0..63] of int64;
CapBlock : array[0..63] of TBitmap;
JpgBlock : array[0..63] of array[0..65535] of byte;
showjpg : array[0..63] of TJpegImage;
showbmp : array[0..63] of TBitmap;
DefWidth,DefHeight,DefDataSize : integer;
procedure OnTimerx(Sender :TObject);
public
{ Public declarations }
end;

var
Form1: TForm1;
procedure ScreenShot(x,y,width,Height:Integer;bm: TBitMap);
function CalcCRC32(p: Pointer; ByteCount: DWORD):int64;
Procedure Socketerror ;

implementation

{$R *.dfm}
Procedure Socketerror ;
begin
end;
function CalcCRC32(p: Pointer; ByteCount: DWORD):int64;
var i: DWORD;
q: ^BYTE;
begin
result:=0;
q := p;
for i := 0 to ByteCount - 1 do begin
result := (result shr 8) xor Table[q^ xor (result and $000000FF)];
Inc(q);
end
end;


procedure ScreenShot(x,y,width,Height:Integer;bm: TBitMap);
var dc: HDC;
lpPal: PLOGPALETTE;
begin
if ((Width = 0) or (Height = 0)) then
Exit;
bm.Width := Width;
bm.Height := Height;
dc := GetDc(0);
if (dc = 0) then
Exit;
if (GetDeviceCaps(dc, RASTERCAPS) and RC_PALETTE = RC_PALETTE) then begin
GetMem(lpPal,SizeOf(TLOGPALETTE)+(255*SizeOf(TPALETTEENTRY)));
FillChar(lpPal^,SizeOf(TLOGPALETTE)+(255*SizeOf(TPALETTEENTRY)),#0);
lpPal^.palVersion := $300;
lpPal^.palNumEntries := GetSystemPaletteEntries(dc,0,256,lpPal^.palPalEntry);
if (lpPal^.PalNumEntries <> 0) then
bm.Palette := CreatePalette(lpPal^);
FreeMem(lpPal, SizeOf(TLOGPALETTE)+(255*SizeOf(TPALETTEENTRY)));
end;
BitBlt(bm.Canvas.Handle,0,0,Width,Height,Dc,x,y,SRCCOPY);
ReleaseDc(0, dc);
end;

procedure TForm1.OnTimerx(Sender :TObject);
var capx,capy : integer;
xstrm : TMemoryStream;
xUDP : TIdUDPClient;
Jpegx: TJpegImage;
begin
with TTimer(Sender) do begin
capx:=(tag mod 8)*DefWidth;
capy:=(tag div 8)*DefHeight;
ScreenShot(capx,capy,DefWidth,Defheight,capblock[tag]);

xstrm:=TMemoryStream.Create;
capblock[tag].SaveToStream(xstrm);
NewCRC[tag]:= CalcCRC32(xstrm.Memory,xstrm.Size);
if NewCRC[tag]<>PriorCRC[tag] then begin
PriorCRC[Tag]:=NewCRC[Tag];
Jpegx:=TJpegImage.Create;
Jpegx.JPEGNeeded;
Jpegx.CompressionQuality:=95;
Jpegx.Smoothing:=true;
Jpegx.Assign(capblock[tag]);
xUDP:=TIdUDPClient.create(nil);
Jpegx.Compress;
xstrm.Clear;
jpgblock[tag][0]:=tag;
jpgblock[tag][1]:=defwidth;
jpgblock[tag][2]:=defheight;
xstrm.writeBuffer(JpgBlock[tag][0],3);
Jpegx.SaveToStream(xstrm);
xstrm.Seek(0,soFromBeginning);
xstrm.ReadBuffer(JpgBlock[tag],xstrm.Size);
xUDP.Host:=Edit1.text;
xUDP.Port:=3333;
try
xUDP.SendBuffer(JpgBlock[tag],xstrm.Size+3);
except
on EIdSocketError do SocketError;
end;

freeandnil(Jpegx);
Freeandnil(xUDP);
end;
freeandnil(xstrm);
end;
end;

procedure TForm1.FormCreate(Sender: TObject);
var x : integer ;
begin
DefWidth:=screen.Width div 8;
DefHeight:=Screen.Height div 8;
DefDataSize:=DefWidth*DefHeight*2; // pf16Bit = 2 Bytes
for x := 0 to 63 do begin
PriorCRC[x]:=0;
NewCRC[x]:=0;
CapBlock[x] := TBitmap.Create;
CapBlock[x].Width:=DefWidth;
CapBlock[x].Height:=DefHeight;
CapBlock[x].PixelFormat:=pf16Bit;
ShowJpg[x]:=TJpegImage.create;
// ShowJpg[x].DIBNeeded;
ShowBmp[x]:=TBitmap.Create;
ShowBmp[x].Width:=defWidth;
ShowBmp[x].height:=defheight;
ShowBmp[x].PixelFormat:=pf16Bit;
end;


for x := 0 to 63 do with TTimer.Create(self) do begin
onTimer:=OnTimerX;
Tag:=x;
Interval:=100;
Enabled := true;
end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
fillchar(PriorCRC,Sizeof(PriorCRC),#0);
end;

end.

远程：
unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, Jpeg, IdBaseComponent, IdComponent, IdUDPBase, IdUDPServer,
ExtCtrls,IdSocketHandle, StdCtrls;

type
TForm1 = class(TForm)
IdUDPServer1: TIdUDPServer;
Button1: TButton;
procedure FormCreate(Sender: TObject);
procedure IdUDPServer1UDPRead(Sender: TObject; AData: TStream;
ABinding: TIdSocketHandle);
procedure FormShow(Sender: TObject);
procedure FormResize(Sender: TObject);
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
ShowJpg: array[0..63] of TJpegImage;
DW,DH: integer;
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
var x: integer;
begin
for x := 0 to 63 do begin
dw:=Form1.Width div 8;
dh:=Form1.Height div 8;
ShowJpg[x]:=TJpegImage.Create;
end;
idUDPServer1.Active:=true;
end;

procedure TForm1.IdUDPServer1UDPRead(Sender: TObject; AData: TStream;
ABinding: TIdSocketHandle);
var temp : array[0..2] of byte;
Jpg : TJpegImage;
ct,CapX,CapY: integer;
bmp: TBitmap;
begin
if aData.Size>0 then begin
AData.ReadBuffer(temp,3);
ct:=temp[0];
capx:=(ct mod 8)*Dw;
capy:=(ct div 8)*DH;
if ct<=63 then with ShowJpg[ct] do begin
LoadFromStream(AData);
DIBNeeded;
Form1.Canvas.StretchDraw(rect(capx,capy,capx+dw,capy+dh),showjpg[ct]);
end;
end;
end;

procedure TForm1.FormShow(Sender: TObject);
begin
dw:=Form1.Width div 8;
dh:=Form1.Height div 8;
end;

procedure TForm1.FormResize(Sender: TObject);
begin
dw:=Form1.Width div 8;
dh:=Form1.Height div 8;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
close;
end;

end.