C++ (Cpp) PageView::setIsVisible Examples

Example #1

File: Layout.cpp Project: gitter-badger/xournalpp

/**
 * Check which page should be selected
 */
void Layout::checkSelectedPage()
{

	GtkAllocation allocation = { 0 };
	gtk_widget_get_allocation(this->view->getWidget(), &allocation);

	int scrollY = this->scrollVertical->getValue();
	int scrollX = this->scrollHorizontal->getValue();

	Control* control = this->view->getControl();

	int viewHeight = allocation.height;
	int viewWidth = allocation.width;
	bool twoPages = control->getSettings()->isShowTwoPages();

	if (scrollY < 1)
	{
		if (twoPages && this->view->viewPagesLen > 1 &&
		    this->view->viewPages[1]->isSelected())
		{
			// page 2 already selected
		}
		else
		{
			control->firePageSelected(0);
		}
		return;
	}

	int mostPageNr = 0;
	double mostPagePercent = 0;

	// next four pages are not marked as invisible,
	// because usually you scroll forward

	for (int page = 0; page < this->view->viewPagesLen; page++)
	{
		PageView* p = this->view->viewPages[page];
		int y = p->getY();
		int x = p->getX();

		int pageHeight = p->getDisplayHeight();
		int pageWidth = p->getDisplayWidth();

		if (y > scrollY + viewHeight)
		{
			p->setIsVisible(false);
			for (; page < this->view->viewPagesLen; page++)
			{
				p = this->view->viewPages[page];
				p->setIsVisible(false);
			}

			break;
		}
		if (y + pageHeight >= scrollY)
		{
			int startY = 0;
			int endY = pageHeight;
			if (y <= scrollY)
			{
				startY = scrollY - y;
			}
			if (y + pageHeight > scrollY + viewHeight)
			{
				endY = pageHeight - ((y + pageHeight) - (scrollY + viewHeight));
			}

			int startX = 0;
			int endX = pageWidth;

			if (x <= scrollX)
			{
				startX = scrollX - x;
			}
			if (x + pageWidth > scrollX + viewWidth)
			{
				endX = pageWidth - ((x + pageWidth) - (scrollX + viewWidth));
			}


			double percent = ((double) (endY - startY)) / ((double) pageHeight);
			percent *= ((double) (endX - startX)) / ((double) pageWidth);

			if (percent > mostPagePercent)
			{
				mostPagePercent = percent;
				mostPageNr = page;
			}

			p->setIsVisible(true);
		}
		else
		{
			p->setIsVisible(false);
		}
	}

	if (twoPages && mostPageNr < this->view->viewPagesLen - 1)
	{
		int y1 = this->view->viewPages[mostPageNr]->getY();
		int y2 = this->view->viewPages[mostPageNr + 1]->getY();

		if (y1 != y2 || !this->view->viewPages[mostPageNr + 1]->isSelected())
		{
			// if the second page is selected DON'T select the first page.
			// Only select the first page if none is selected
			control->firePageSelected(mostPageNr);
		}
	}
	else
	{
		control->firePageSelected(mostPageNr);
	}
}