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Microsoft Windows NT Build 297 06-28-1992

 Sample: StretchBlt Demonstration

Summary:

The STRETCH sample is an easy to use demonstration of the
StretchBlt API function. The program presents a dialog box
on the top of the window, and through this dialog box the
user can manipulate the parameters to StretchBlt. In the
main window, the source bitmap is displayed on the right
half of the window, and the destination bitmap is displayed
on the left half.

More Information:

The source and destination rectangles may be changed
directly in the dialog, or they may be changed by using the
direct manipulation objects in the two halves of the window.
Clicking and dragging the mouse in the upper-left corner
moves the rectangles; clicking and dragging the mouse in the
lower-right corner sizes the rectangles. The source direct
manipulation object is temporarily erased before calling
StretchBlt so that the top and left edges do not show in the
destination image.

The raster operation for the StretchBlt call may be changed
by altering the values in the right-most entry fields. The
contents are interpreted to be in hexadecimal. There is a
combo box directly beneath these entry fields that lists all
of the standard raster operations. If the user selects a
standard ROP from this combo box, its contents are copied
into the ROP entry fields and are then used in the
StretchBlt call.

Several of the raster operations make use of a pattern in
the destination HDC. For this reason, the program also
allows the user to select one of the standard pattern
brushes from a second combo box. This brush is selected into
the destination HDC just prior to making the StretchBlt
call.

The effect of the StretchBlt call is also affected by the
"StretchBlt mode" that has been set for the destination HDC.
A third combo box allows the user to select from any of the
standard modes. The difference is most easily observed when
stretching from a large source rectangle to a small
destination rectangle.

The "Draw" button may be chosen at any time to cause the
StretchBlt call to be made. This does not erase the
background, so that the effect of multiple ROPs on the HDC
can be observed. Manipulating the source rectangle also
causes a StretchBlt to occur without erasing the window.
However, manipulating the destination rectangle erases the
destination half of the window before the next StretchBlt is
called.

The following is a list of the Win32 API functions used in
this sample:

   _lclose           DispatchMessa  LoadAccelerator  ReleaseDC
                     ge             s
   _lopen            DPtoLP         LoadCursor       SelectClipRgn
   _lread            EndPaint       LoadIcon         SelectObject
   AngleArc          GetClientRect  LocalAlloc       SendDlgItemMes
                                                     sage
   BeginPaint        GetClipboardD  LocalFree        SendMessage
                     ata
   BitBlt            GetDC          LocalHandle      SetCapture
   ClientToScreen    GetDlgItemInt  LPtoDP           SetClipboardDa
                                                     ta
   CloseClipBoard    GetDlgItemTex  MessageBox       SetCursorPos
                     t
   CreateCompatible  GetFileSize    ModifyWorldTran  SetDlgItemInt
   Bitmap                           sform
   CreateCompatible  GetMessage     MoveToEx         SetDlgItemText
   DC
   CreateDialog      GetObject      OpenClipboard    SetROP2
   CreateDIBitmap    GetStockObjec  OpenFile         SetStretchBltM
                     t                               ode
   CreatePen         GetViewportOr  PostMessage      SetViewportOrg
                     gEx                             Ex
   CreateRectRgnInd  GetWorldTrans  PostQuitMessage  SetWindowPos
   irect             form
   CreateWindow      InvalidateRec  PtInRect         SetWorldTransf
                     t                               orm
   DeleteDC          IsWindow       Rectangle        ShowWindow
   DeleteObject      LineTo         ReleaseCapture   StretchBlt

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