/* BigView.C - (c) 1987 DJH

	BigView will display any IFF picture independent of the physical
  display size. Default display size is 320 x 200 lo-res; HIRES or LACE
  attributes added if user width/height exceeds low resolution boundaries.

	Note that we do not actually call ScrollVPort, since we want to
  maintain Intuition compatability; the principle is the same, however.
  Note that not all screen widths/resolutions scroll equally smoothly;
  experiment! Also : the Rx/RyOffsets seem able to exceed the 1K RKM
  limitations; investigate.
*/
 
#include "iff.h" /* ReadILBM.C defines */

void *IntuitionBase,*GfxBase;

main(argc,argv)
int argc;
char *argv[];
{
  struct PicMap picmap;
  struct NewScreen newscreen;
  struct Screen *screen;
  int status,dwidth,dheight,i;

  switch(argc) {
    case 0:  exit(0); break; /* arrgh! WorkBench! */
    case 2:  dwidth=320; dheight=200; break;
    case 4:  sscanf(argv[2],"%d",&dwidth);
             sscanf(argv[3],"%d",&dheight);
             break;
    default: puts("BigView file [width,height]"); exit(0);
  }
 
  IntuitionBase=OpenLibrary("intuition.library",0);
  GfxBase=OpenLibrary("graphics.library",0);

  if (ReadILBM(argv[1],0,&picmap)) exit(0);

  setmem(&newscreen,sizeof(newscreen),0);

  /* user dimensions can be smaller, but not larger than picture! */

  if (dwidth>picmap.BitMap.BytesPerRow*8) dwidth=picmap.BitMap.BytesPerRow*8;
  if (dheight>picmap.BitMap.Rows) dheight=picmap.BitMap.Rows;
  
  newscreen.Width=dwidth; newscreen.Height=dheight;  

  newscreen.ViewModes=picmap.ViewModes & HAM; /* WE decide other bits */

  if (dwidth>LOWIDTH) newscreen.ViewModes|=HIRES;
  if (dheight>LOHEIGHT) newscreen.ViewModes|=LACE;

  newscreen.Type=CUSTOMSCREEN|CUSTOMBITMAP;
  newscreen.Depth=picmap.BitMap.Depth;
  newscreen.CustomBitMap=&picmap.BitMap;
  newscreen.DetailPen=0; newscreen.BlockPen=1;

  screen=OpenScreen(&newscreen);
  LoadRGB4(&screen->ViewPort,&picmap.colormap[0],1<<newscreen.Depth);

  Scroll_Around(screen,dwidth,dheight); Delay(200);

  CloseScreen(screen); FreeBitMap(&picmap.BitMap);
}

Scroll_Around(screen,dwidth,dheight)
struct Screen *screen;
int dwidth,dheight;
{
  short i,
        xdelta=screen->BitMap.BytesPerRow*8-dwidth,
        ydelta=screen->BitMap.Rows-dheight;

  if (xdelta) /* any room to scroll right? */ 
    for (i=1;i<=xdelta;i++) {
      screen->ViewPort.RasInfo->RxOffset=i;
      MakeScreen(screen);
      RethinkDisplay();
    }

  if (ydelta) /* any room to scroll down? */
    for (i=1;i<=ydelta;i++) {
      screen->ViewPort.RasInfo->RyOffset=i;
      MakeScreen(screen);
      RethinkDisplay();
    }

  if (xdelta)
    for (i=xdelta;i;i--) {
      screen->ViewPort.RasInfo->RxOffset=i-1;
      MakeScreen(screen);
      RethinkDisplay();
    }

  if (ydelta)
    for (i=ydelta;i;i--) {
      screen->ViewPort.RasInfo->RyOffset=i-1;
      MakeScreen(screen);
      RethinkDisplay();
    }
}