PRB: Image Functions Fail with Image Outside of Viewport

• Microsoft FORTRAN PowerStation for MS-DOS, versions 1.0a

SYMPTOMS

The image functions SAVEIMAGE, SAVEIMAGE_W, LOADIMAGE, and LOADIMAGE_W fail when the specified image falls outside the current viewport. After SAVEIMAGE fails, calling GRSTATUS will return: $GRIMAGEREADERROR.

CAUSE

Though not documented, this behavior is by design. The functions listed above will fail when you attempt to place even part of an image outside the viewport. Images are never clipped to the viewport.

RESOLUTION

Do not attempt to place images outside of the current viewport. Either make the viewport larger or work with partial (smaller) images.

STATUS

This behavior does occur with FORTRAN PowerStation 32.

MORE INFORMATION

This problem is similar to the problem described in the following article in the Microsoft Knowledge Base, which discusses PUTIMAGE, GETIMAGE, PUTIMAGE_W, and GETIMAGE_W:

ARTICLE-ID: Q118682

TITLE     : PRB: Image Functions Fail with Image Outside of Viewport

   Saving full viewport returns:           0
   Saving outside viewport returns:         -1
   Saving outside viewport GRSTATUS: $GRIMAGEREADERROR

Sample Code

C Compile options needed: none

      include 'fgraph.fi'
      include 'fgraph.fd'

      integer*2 i, ret(3)

      i = setvideomode($VRES16COLOR)
      call setviewport(10,10,20,20)
      ret(1) = saveimage("test.bmp",0,0,10,10)
      ret(2) = saveimage("test2.bmp",0,0,10,11)
      ret(3) = GRSTATUS()

      i = setvideomode($DEFAULTMODE)

      print *, "Saving full viewport returns:", ret(1)
      print *, "Saving outside viewport returns:", ret(2)
      if (ret(3) .eq. $GRIMAGEREADERROR)
     +    print *, "Saving outside viewport GRSTATUS: $GRIMAGEREADERROR"

      end