#include <guitar/scrollinfo.hpp>

bool ScrollInfo::pageDown(void)
{
  int yDelta;
	int yNew;
  int xDelta;

	xDelta=0;
  yNew=currScrolly()+PageIncrement;
	yNew=imax(0,yNew);
	yNew=imin(maxScrolly(),yNew);
	if(yNew==currScrolly())return false;
	scrollEvent(TRUE);
	yDelta=yNew-currScrolly();
	currScrolly(yNew);
	::ScrollWindow(hwndOwner(),-xDelta,-yDelta,(const RECT*)0,(const RECT*)0);
	::UpdateWindow(hwndOwner());
	::SetScrollPos(hwndOwner(),SB_VERT,currScrolly(),TRUE);
	return true;
}

bool ScrollInfo::pageUp(void)
{
  int yDelta;
	int yNew;
  int xDelta;

	xDelta=0;
  yNew=currScrolly()-PageIncrement;
	yNew=imax(0,yNew);
	yNew=imin(maxScrolly(),yNew);
	if(yNew==currScrolly())return false;
	scrollEvent(TRUE);
	yDelta=yNew-currScrolly();
	currScrolly(yNew);
	::ScrollWindow(hwndOwner(),-xDelta,-yDelta,(const RECT*)0,(const RECT*)0);
	::UpdateWindow(hwndOwner());
	::SetScrollPos(hwndOwner(),SB_VERT,currScrolly(),TRUE);
	return true;
}

void ScrollInfo::handleHorizontalScroll(CallbackData &someCallbackData)
{
  int xDelta;
	int yDelta;
	int xNew;

	yDelta=0;
	switch(LOWORD(someCallbackData.wParam()))
	{
	  case SB_PAGEUP :
		  xNew=currScrollx()-PageIncrement;
		  break;
		case SB_PAGEDOWN :
		  xNew=currScrollx()+PageIncrement;
		  break;
		case SB_LINEUP :
		  xNew=currScrollx()-LineIncrement;
		  break;
		case SB_LINEDOWN :
		  xNew=currScrollx()+LineIncrement;
		  break;
		case SB_THUMBPOSITION :
		  xNew=	HIWORD(someCallbackData.wParam());
		  break;
		default :
		  xNew=currScrollx();
			break;
	}
	xNew=imax(0,xNew);
	xNew=imin(maxScrollx(),xNew);
	if(xNew==currScrollx())return;
	scrollEvent(TRUE);
	xDelta=xNew-currScrollx();
	currScrollx(xNew);
	::ScrollWindow(hwndOwner(),-xDelta,-yDelta,(const RECT*)0,(const RECT*)0);
	::UpdateWindow(hwndOwner());
	::SetScrollPos(hwndOwner(),SB_HORZ,currScrollx(),TRUE);
}

void ScrollInfo::handleVerticalScroll(CallbackData &someCallbackData)
{
  int yDelta;
	int yNew;
  int xDelta;

	xDelta=0;
	switch(LOWORD(someCallbackData.wParam()))
	{
	  case SB_PAGEUP :
		  yNew=currScrolly()-PageIncrement;
		  break;
		case SB_PAGEDOWN :
		  yNew=currScrolly()+PageIncrement;
		  break;
		case SB_LINEUP :
		  yNew=currScrolly()-LineIncrement;
		  break;
		case SB_LINEDOWN :
		  yNew=currScrolly()+LineIncrement;
		  break;
		case SB_THUMBPOSITION :
		  yNew=HIWORD(someCallbackData.wParam());
		  break;
		default :
		  yNew=currScrolly();
			break;
	}
	yNew=imax(0,yNew);
	yNew=imin(maxScrolly(),yNew);
	if(yNew==currScrolly())return;
	scrollEvent(TRUE);
	yDelta=yNew-currScrolly();
	currScrolly(yNew);
	::ScrollWindow(hwndOwner(),-xDelta,-yDelta,(const RECT*)0,(const RECT*)0);
	::UpdateWindow(hwndOwner());
	::SetScrollPos(hwndOwner(),SB_VERT,currScrolly(),TRUE);
}

void ScrollInfo::handleSize(CallbackData &someCallbackData)
{
  int xNew(someCallbackData.loWord());
	int yNew(someCallbackData.hiWord());

	sizeEvent(TRUE);
	maxScrollx(imax(scrollableObjectWidth()-xNew,0));
	::SetScrollRange(hwndOwner(),SB_HORZ,minScrollx(),maxScrollx(),FALSE);
	currScrollx(imin(currScrollx(),maxScrollx()));
	::SetScrollPos(hwndOwner(),SB_HORZ,currScrollx(),TRUE);
	maxScrolly(imax(scrollableObjectHeight()-yNew,0));
	::SetScrollRange(hwndOwner(),SB_VERT,minScrolly(),maxScrolly(),FALSE);
	currScrolly(imin(currScrolly(),maxScrolly()));
	::SetScrollPos(hwndOwner(),SB_VERT,currScrolly(),TRUE);
}