Method DrawVisibleAreaRect

Src/LocationView.cpp:877–935

* @brief Draws rect indicating visible area in file views. * * @param [in] nTopLine New topline for indicator * @param [in] nBottomLine New bottomline for indicator * @todo This function duplicates too much DrawRect() code. */

 * @todo This function duplicates too much DrawRect() code.
 */
void CLocationView::DrawVisibleAreaRect(CDC *pClientDC, int nTopLine, int nBottomLine)
{
	CMergeDoc* pDoc = GetDocument();
	int nGroup = pDoc->GetActiveMergeView()->m_nThisGroup;
	
	if (nTopLine == -1)
		nTopLine = pDoc->GetView(nGroup, 0)->GetTopSubLine();
	
	if (nBottomLine == -1)
	{
		const int nScreenLines = pDoc->GetView(nGroup, 1)->GetScreenLines();
		nBottomLine = nTopLine + nScreenLines;
	}

	const int lpx = pClientDC->GetDeviceCaps(LOGPIXELSX);
	auto pointToPixel = [lpx](int point) { return MulDiv(point, lpx, 72); };

	CRect rc;
	GetClientRect(rc);
	int nbLines = INT_MAX;
	pDoc->ForEachActiveGroupView([&](auto& pView) {
		nbLines = min(nbLines, pView->GetSubLineCount());
	});

	int nTopCoord = static_cast<int>(Y_OFFSET +
			(static_cast<double>(nTopLine * m_lineInPix)));
	int nBottomCoord = static_cast<int>(Y_OFFSET +
			(static_cast<double>(nBottomLine * m_lineInPix)));
	
	double xbarBottom = min(nbLines / m_pixInLines + Y_OFFSET, rc.Height() - Y_OFFSET);
	int barBottom = (int)xbarBottom;
	// Make sure bottom coord is in bar range
	nBottomCoord = min(nBottomCoord, barBottom);

	// Ensure visible area is at least minimum height
	if (nBottomCoord - nTopCoord < INDICATOR_MIN_HEIGHT)
	{
		// If area is near top of file, add additional area to bottom
		// of the bar and vice versa.
		if (nTopCoord < Y_OFFSET + 20)
			nBottomCoord += INDICATOR_MIN_HEIGHT - (nBottomCoord - nTopCoord);
		else
		{
			// If we have a high number of lines, it may be better
			// to keep the topline, otherwise the cursor can 
			// jump up and down unexpected
			nBottomCoord = nTopCoord + INDICATOR_MIN_HEIGHT;
		}
	}

	// Store current values for later use (to check if area changes)
	m_visibleTop = nTopCoord;
	m_visibleBottom = nBottomCoord;

	CRect rcVisibleArea(2, m_visibleTop, rc.right - 2, m_visibleBottom);
	std::unique_ptr<CBitmap> pBitmap(CopyRectToBitmap(pClientDC, rcVisibleArea));
	std::unique_ptr<CBitmap> pDarkenedBitmap(GetDarkenedBitmap(pClientDC, pBitmap.get(), pointToPixel(3), IsColorDark(GetBackgroundColor())));
	DrawBitmap(pClientDC, rcVisibleArea.left, rcVisibleArea.top, pDarkenedBitmap.get());