rom/graphics/scrollvport.c

   1 /*
   2     Copyright © 1995-2010, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Graphics function ScrollVPort()
   6     Lang: english
   7 */
   8
   9 #include <aros/debug.h>
  10 #include <proto/oop.h>
  11
  12 #include "graphics_intern.h"
  13 #include "gfxfuncsupport.h"
  14
  15 /*****************************************************************************
  16
  17     NAME */
  18 #include <proto/graphics.h>
  19
  20         AROS_LH1(void, ScrollVPort,
  21
  22 /*  SYNOPSIS */
  23         AROS_LHA(struct ViewPort *, vp, A0),
  24
  25 /*  LOCATION */
  26         struct GfxBase *, GfxBase, 98, Graphics)
  27
  28 /*  FUNCTION
  29
  30     INPUTS
  31
  32     RESULT
  33
  34     NOTES
  35         AROS video drivers can perform a validation of offsets, and may refuse
  36         to scroll the screen too far (if they somehow can't provide the requested
  37         offset). In this case offset values in the ViewPort will be updated in
  38         order to reflect the real result of the operation.
  39
  40     EXAMPLE
  41
  42     BUGS
  43
  44     SEE ALSO
  45
  46     INTERNALS
  47
  48     HISTORY
  49
  50
  51 ******************************************************************************/
  52 {
  53     AROS_LIBFUNC_INIT
  54
  55     /* We use obtain/release pair because this makes ScrollVPort()
  56        operating also on planar bitmaps, which can aid in porting AROS
  57        to m68k Amiga */
  58     OOP_Object *bitmap = OBTAIN_HIDD_BM(vp->RasInfo->BitMap);
  59     IPTR tags[] = {
  60         aHidd_BitMap_LeftEdge, vp->DxOffset,
  61         aHidd_BitMap_TopEdge,  vp->DyOffset,
  62         TAG_DONE
  63     };
  64     IPTR offset;
  65
  66     /* Actually move the bitmap */
  67     OOP_SetAttrs(bitmap, tags);
  68
  69     /* The bitmap may fail to move. Fix up offsets now */
  70     OOP_GetAttr(bitmap, aHidd_BitMap_LeftEdge, &offset);
  71     vp->DxOffset = offset;
  72     OOP_GetAttr(bitmap, aHidd_BitMap_TopEdge, &offset);
  73     vp->DyOffset = offset;
  74
  75     RELEASE_HIDD_BM(bitmap, vp->RasInfo->BitMap);
  76
  77     AROS_LIBFUNC_EXIT
  78 } /* ScrollVPort */