delphi映像内存发送端
映像内存发送端
发送端利用CreateFileMapping 函数建立内存映像文件，并用MapViewOfFile 函数将映像文件映射到本进行中，并利用PostMessage 发送信息，具体步骤及方法如下。
（1）新建一个项目。将窗体的Caption 设置为“映像内存发送端”。在窗体上添加一个Caption 属性为“发送数据”的Button 组件。
（2）程序源代码如下：
unit Unit1;
interface
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls;
const
WM_DATA = WM_USER + 1024;
type
PShareMem = ^TShareMem;
TShareMem = record
Data: array[0..255] of char;
end;
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
PShare: PShareMem;
implementation
{$R *.DFM}
var
HMapping: THandle;
HMapMutex: THandle;
const
MAPFILESIZE = 1000;
REQUEST_TIMEOUT = 1000;
procedure OpenMap; //打开建立共享内存
begin
{创建一个文件映射内核对象}
HMapping := CreateFileMapping(
$FFFFFFFF,
nil,
PAGE_READWRITE,
0,
SizeOf(TShareMem),
pchar(’Map Name’) {映像文件的名字是’Map Name’}
);
if (hMapping = 0) then
begin
ShowMessage(’不能创建内存映射文件’);
Application.Terminate;
exit;
end;
{将映像文件映射到进程的地址空间}
PShare := PShareMem(MapViewOfFile(HMapping, FILE_MAP_ALL_ACCESS, 0, 0, 0));
if PShare = nil then
begin
CloseHandle(HMapping);
ShowMessage(’Can’’t View Memory Map’);
Application.Terminate;
exit;
end;
end;
procedure CloseMap; //关闭共享内存
begin
if PShare <> nil then
{从进程的地址空间中撤消文件数据的映像}
UnMapViewOfFile(PShare);
if HMapping <> 0 then
CloseHandle(HMapping); //关闭映像文件
end;
function LockMap: Boolean; //建立互斥对象
begin
Result := true;
{创建互斥对象}
HMapMutex := CreateMutex(nil, false,
pchar(’MY MUTEX NAME GOES HERE’));
if HMapMutex = 0 then
begin
ShowMessage(’不能创建互斥对象’);
Result := false;
end else begin
if WaitForSingleObject(HMapMutex, REQUEST_TIMEOUT)
= WAIT_FAILED then
begin
ShowMessage(’不能对互斥对象加锁!’);
Result := false;
end;
end;
end;
procedure UnlockMap; //释放互斥对象
begin
ReleaseMutex(HMapMutex);
CloseHandle(HMapMutex);
end;
procedure TForm1.Button1Click(Sender: TObject);
var
str: pchar;
begin
str := pchar(’简单的共享内存的例子’);
CopyMemory(@(pShare^.data), Str, Length(str));
{发送消息表明有数据}
PostMessage(FindWindow(nil, ’映像内存接收端’), WM_DATA, 1, 1)
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
UnlockMap;
CloseMap;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
OpenMap;
LockMap;
end;
end.
（3）保存工程为“SendDemo.dpr”。
