.data?
g_hInstance HINSTANCE ?
g_ScrRect   RECT    <>
.code
start:
    invoke GetModuleHandle, NULL
    mov    g_hInstance, eax
    ;m_m2m g_ScrRect.top, 0
    ;m_m2m g_ScrRect.left, 0
    ;m_m2m g_ScrRect.bottom, 200
    ;m_m2m g_ScrRect.right, 100
    invoke DialogBoxParam, g_hInstance, IDD_dlgCopyScr, NULL, OFFSET DlgProc,  NULL
    invoke ExitProcess, eax
DlgProc proc hWnd: HWND, uMsg: UINT, wParam: WPARAM, lParam: LPARAM
    .IF uMsg == WM_CLOSE
        invoke EndDialog, hWnd, NULL
 ;.ELSEIF uMsg == WM_INITDIALOG
    .ELSEIF (uMsg == WM_COMMAND)
        mov eax, wParam
        mov edx, eax
        shr edx, 16
        .if (dx == BN_CLICKED)              ;If button is clicked
            .IF (eax ==  IDC_btnCopyScr)
                invoke GetDesktopWindow
                invoke GetWindowRect, eax, ADDR g_ScrRect
                invoke CopyScreenToBitmap, ADDR g_ScrRect
                push eax
                invoke CopyBMPtoClipboard, eax, hWnd
                pop eax
                invoke DrawBMP, hWnd, eax
            .ENDIF
        .endif
    .ELSE
        mov eax, FALSE
        ret
    .ENDIF
    mov eax, TRUE
    ret
DlgProc endp
; lpRect 为指向要拷贝的屏幕区域的坐标结构的指针
CopyScreenToBitmap proc lpRect: DWORD
    LOCAL hScrDC, hMemDC: HDC       ;屏幕和内存设备描述表
    LOCAL hBitmap, hOldBitmap: HBITMAP    ;位图句柄
    LOCAL nX, nY, nX2, nY2: DWORD         ;选定区域坐标
    LOCAL nWidth, nHeight: DWORD          ;位图宽度和高度
    LOCAL xScrn, yScrn: DWORD             ;屏幕分辨率
    ;判断选定区域是否为空矩形
    invoke  IsRectEmpty, lpRect
    or eax, eax
    jz @F
    ;m_m2m eax, 1    ;是空矩形
    ret
@@:    
    ;为屏幕创建设备描述表
    xor eax, eax
    jz @F
    szDisplay db "DISPLAY", 0
@@:    
    invoke CreateDC, ADDR szDisplay, NULL, NULL, NULL
    cmp eax, NULL
    jne @F
    ;m_m2m eax, 2    ;不能创建DC
    ret
@@:    
    mov hScrDC, eax
   ;为屏幕设备描述表创建兼容的内存设备描述表
    invoke CreateCompatibleDC, hScrDC
    cmp eax, NULL
    jne @F
    ;m_m2m eax, 3    ;不能创建兼容的内存设备描述表
    ret
@@:    
    mov hMemDC, eax
    ;获得选定区域坐标
    mov eax, lpRect
    assume eax: ptr RECT
    m_m2m nX, [eax].left
    m_m2m nY, [eax].top
    m_m2m nX2, [eax].right
    m_m2m nY2, [eax].bottom
    assume eax: nothing
    ;获得屏幕分辨率
    invoke GetDeviceCaps, hScrDC, HORZRES
    mov xScrn, eax
    invoke GetDeviceCaps, hScrDC, VERTRES
    mov yScrn, eax
    ;确保选定区域是可见的
    .if (nX < 0)
        m_m2m nX, 0
    .endif
    .if (nY < 0)
        m_m2m nY, 0
    .endif
    mov eax, nX2
    .if (eax > xScrn)
        m_m2m nX2, xScrn
    .endif
    mov eax, nY2
    .if (eax > yScrn)
        m_m2m nY2, yScrn
    .endif
    mov eax, nX2
    sub eax, nX
    mov  nWidth, eax
    
    mov eax, nY2
    sub eax, nY
    mov nHeight, eax
    ;创建一个与屏幕设备描述表兼容的位图
    invoke CreateCompatibleBitmap, hScrDC, nWidth, nHeight
    cmp eax, NULL
    jne @F
    ;m_m2m eax, 4    ;不能创建屏幕设备描述表兼容的位图
    ret
@@:    
    mov hBitmap, eax
   ;把新位图选到内存设备描述表中
    invoke SelectObject, hMemDC, hBitmap
    cmp eax, NULL
    jne @F
    ;m_m2m eax, 5    ;an error occurs and the selected object is not a region
    ret
@@:    
    cmp eax, GDI_ERROR
    jne @F
    ;m_m2m eax, 6
    ret
@@:    
    mov hOldBitmap, eax
    ;把屏幕设备描述表拷贝到内存设备描述表中
    invoke BitBlt, hMemDC, 0, 0, nWidth, nHeight, hScrDC, nX, nY, SRCCOPY
    ;得到屏幕位图的句柄
    invoke SelectObject, hMemDC, hOldBitmap
    push eax    ;mov hBitmap, eax
   ;清除
    invoke DeleteDC, hScrDC
    invoke DeleteDC, hMemDC
    ;返回位图句柄
    pop eax     ;mov eax, hBitmap
    ret
CopyScreenToBitmap endp
;得到屏幕位图句柄以后,我们可以把屏幕内容粘贴到剪贴板上
;hBitmap: 位图句柄
;hWnd: 程序窗口句柄
CopyBMPtoClipboard proc hBitmap: HANDLE, hWnd: HWND
    invoke OpenClipboard, hWnd  ;
    or eax, eax
    jnz @F
    m_m2m eax, 1
    ret
@@:
    ;清空剪贴板
    invoke EmptyClipboard
    or eax, eax
    jnz @F
    m_m2m eax, 2
    ret
@@:
    ;把位图内容粘贴到剪贴板上
    invoke SetClipboardData, CF_BITMAP, hBitmap
    or eax, eax
    jnz @F
    m_m2m eax, 3
    ret
@@:
    ;关闭剪贴板
    invoke CloseClipboard
    or eax, eax
    jnz @F
    m_m2m eax, 4
    ret
@@:
    xor eax, eax
    ret
CopyBMPtoClipboard endp
;在指定窗口上绘制位图
DrawBMP proc hWnd: HWND, hBmp: HANDLE
    LOCAL hDC: HDC
    LOCAL hOld: DWORD
    LOCAL memDC :DWORD
    invoke GetDC, hWnd
    mov hDC, eax
    invoke CreateCompatibleDC, eax
    mov memDC, eax
    
    invoke SelectObject, memDC, hBmp
    mov hOld, eax
    invoke BitBlt, hDC, 120, 0, 1000, 1000, memDC, 0, 0, SRCCOPY
    invoke SelectObject, hDC, hOld
    invoke DeleteDC, memDC
    invoke DeleteDC, hDC
    ;xor eax, eax
    ret
DrawBMP endp
end start
;<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
;资源文件rsrc.rc
;<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
#include "\masm32\include\resource.h"
#define IDD_dlgcopyScr              8000
#define IDC_btnCopyScr              1008
IDD_dlgcopyScr DIALOG 20, 20, 295, 165
STYLE 0x0004 | DS_CENTER | WS_CAPTION | DS_SYSMODAL | WS_SYSMENU | WS_MINIMIZEBOX
      | WS_VISIBLE | WS_OVERLAPPED | DS_MODALFRAME | DS_3DLOOK
CAPTION "拷贝屏幕"
{
  PUSHBUTTON      "&C 拷贝屏幕", IDC_btnCopyScr, 5, 5, 52, 52, WS_BORDER
}