rom/graphics/scrollvport.c

   1 /*
   2     Copyright © 1995-2011, 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 "compositing_driver.h"
  14 #include "gfxfuncsupport.h"
  15
  16 /*****************************************************************************
  17
  18     NAME */
  19 #include <proto/graphics.h>
  20
  21         AROS_LH1(void, ScrollVPort,
  22
  23 /*  SYNOPSIS */
  24         AROS_LHA(struct ViewPort *, vp, A0),
  25
  26 /*  LOCATION */
  27         struct GfxBase *, GfxBase, 98, Graphics)
  28
  29 /*  FUNCTION
  30         Move the ViewPort to the position specified in DxOffset and DyOffset
  31         members of the ViewPort structure.
  32
  33     INPUTS
  34
  35     RESULT
  36         None.
  37
  38     NOTES
  39         AROS video drivers can perform a validation of offsets, and may refuse
  40         to scroll the screen too far (if they somehow can't provide the requested
  41         offset). In this case offset values in the ViewPort will be updated in
  42         order to reflect the real result of the operation.
  43
  44     EXAMPLE
  45
  46     BUGS
  47
  48     SEE ALSO
  49
  50     INTERNALS
  51
  52     HISTORY
  53
  54 ******************************************************************************/
  55 {
  56     AROS_LIBFUNC_INIT
  57
  58     /*
  59      * Bitmap object pointer is contained in struct ViewPortData,
  60      * connected to a ViewPortExtra.
  61      * This is true even for planar Amiga bitmaps.
  62      */
  63     struct ViewPortExtra *vpe = (struct ViewPortExtra *)GfxLookUp(vp);
  64
  65     if (vpe)
  66     {
  67         OOP_Object *bm = VPE_DATA(vpe)->Bitmap;
  68         struct monitor_driverdata *mdd = VPE_DRIVER(vpe);
  69         IPTR x = vp->DxOffset;
  70         IPTR y = vp->DyOffset;
  71         BOOL compositing = FALSE;
  72
  73         D(bug("[ScrollVPort] ViewPort 0x%p, Extra 0x%p, composer 0x%p, offset (%ld, %ld)\n", vp, vpe, mdd->composer, x, y));
  74
  75         /*
  76          * First we actually move the bitmap.
  77          * If we are using software composition, this will update bitmap's offsets, for
  78          * the case if this move will cause the screen to be completely covered with this
  79          * bitmap (while previously it was not). In this case the composer will dispose
  80          * own working bitmap and display our bitmap instead. In effect of position update
  81          * it will appear already in correct position. This will improve visual appearance
  82          * of the scrolling.
  83          */
  84         OOP_SetAttrsTags(bm, aHidd_BitMap_LeftEdge, x, aHidd_BitMap_TopEdge, y, TAG_DONE);
  85
  86         if (mdd->composer)
  87         {
  88             /*
  89              * Perform the operation via software composer.
  90              * x and y will be updated to the validated values.
  91              */
  92             compositing = composer_ScrollBitMap(mdd->composer, bm, &x, &y, GfxBase);
  93
  94             if (compositing)
  95             {
  96                 /*
  97                  * Composition is active.
  98                  * Uninstall the framebuffer from the frontmost bitmap,
  99                  */
 100                 UninstallFB(mdd);
 101             }
 102             else if (!mdd->bm_bak)
 103             {
 104                 /*
 105                  * Composition is inactive. Install the framebuffer into the frontmost
 106                  * bitmap, if not already done.
 107                  * This will actually trigger only once, when composition switched from
 108                  * active to inactive state.
 109                  */
 110                 InstallFB(mdd, GfxBase);
 111             }
 112         }
 113
 114         /* The bitmap may fail to move. Fix up offsets now. */
 115         if (!compositing)
 116         {
 117             /*
 118              * If software composition is inactive, we have our bitmap on display.
 119              * Get validated offsets from it.
 120              */
 121             OOP_GetAttr(bm, aHidd_BitMap_LeftEdge, &x);
 122             OOP_GetAttr(bm, aHidd_BitMap_TopEdge, &y);
 123         }
 124
 125         D(bug("[ScrollVPort] Resulting offset (%ld, %ld), composition %d\n", x, y, compositing));
 126
 127         vp->DxOffset = x;
 128         vp->DyOffset = y;
 129     }
 130
 131     AROS_LIBFUNC_EXIT
 132 } /* ScrollVPort */