oak-editor/app/widget/flowlayout/flowlayout.cpp

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#include <QtWidgets>

#include "flowlayout.h"
FlowLayout::FlowLayout(QWidget *parent, int margin, int h_spacing, int v_spacing)
	: QLayout(parent)
	, m_hSpace_(h_spacing)
	, m_vSpace_(v_spacing)
{
	setContentsMargins(margin, margin, margin, margin);
}

FlowLayout::FlowLayout(int margin, int h_spacing, int v_spacing)
	: m_hSpace_(h_spacing)
	, m_vSpace_(v_spacing)
{
	setContentsMargins(margin, margin, margin, margin);
}

FlowLayout::~FlowLayout()
{
	QLayoutItem *item;
	while ((item = takeAt(0)))
		delete item;
}

void FlowLayout::addItem(QLayoutItem *item)
{
	itemList_.append(item);
}

int FlowLayout::horizontal_spacing() const
{
	if (m_hSpace_ >= 0) {
		return m_hSpace_;
	} else {
		return smart_spacing(QStyle::PM_LayoutHorizontalSpacing);
	}
}

int FlowLayout::vertical_spacing() const
{
	if (m_vSpace_ >= 0) {
		return m_vSpace_;
	} else {
		return smart_spacing(QStyle::PM_LayoutVerticalSpacing);
	}
}

int FlowLayout::count() const
{
	return itemList_.size();
}

QLayoutItem *FlowLayout::itemAt(int index) const
{
	return itemList_.value(index);
}

QLayoutItem *FlowLayout::takeAt(int index)
{
	if (index >= 0 && index < itemList_.size())
		return itemList_.takeAt(index);
	else
		return 0;
}

Qt::Orientations FlowLayout::expandingDirections() const
{
	return Qt::Horizontal | Qt::Vertical;
}

bool FlowLayout::hasHeightForWidth() const
{
	return true;
}

int FlowLayout::heightForWidth(int width) const
{
	int height = do_layout(QRect(0, 0, width, 0), true);
	return height;
}

void FlowLayout::setGeometry(const QRect &rect)
{
	QLayout::setGeometry(rect);
	do_layout(rect, false);
}

QSize FlowLayout::sizeHint() const
{
	return minimumSize();
}

QSize FlowLayout::minimumSize() const
{
	QSize size;
	QLayoutItem *item;
	foreach (item, itemList_)
		size = size.expandedTo(item->minimumSize());

	size += QSize(2 * contentsMargins().left(), 2 * contentsMargins().top());
	return size;
}

int FlowLayout::do_layout(const QRect &rect, bool test_only) const
{
	int left, top, right, bottom;
	getContentsMargins(&left, &top, &right, &bottom);
	QRect effective_rect = rect.adjusted(+left, +top, -right, -bottom);
	int x = effective_rect.x();
	int y = effective_rect.y();
	int line_height = 0;

	QLayoutItem *item;
	foreach (item, itemList_) {
		QWidget *wid = item->widget();
		int space_x = horizontal_spacing();
		if (space_x == -1)
			space_x = wid->style()->layoutSpacing(QSizePolicy::PushButton,
												 QSizePolicy::PushButton,
												 Qt::Horizontal);
		int space_y = vertical_spacing();
		if (space_y == -1)
			space_y = wid->style()->layoutSpacing(
				QSizePolicy::PushButton, QSizePolicy::PushButton, Qt::Vertical);
		int next_x = x + item->sizeHint().width() + space_x;
		if (next_x - space_x > effective_rect.right() && line_height > 0) {
			x = effective_rect.x();
			y = y + line_height + space_y;
			next_x = x + item->sizeHint().width() + space_x;
			line_height = 0;
		}

		if (!test_only)
			item->setGeometry(QRect(QPoint(x, y), item->sizeHint()));

		x = next_x;
		line_height = qMax(line_height, item->sizeHint().height());
	}
	return y + line_height - rect.y() + bottom;
}
int FlowLayout::smart_spacing(QStyle::PixelMetric pm) const
{
	QObject *parent = this->parent();
	if (!parent) {
		return -1;
	} else if (parent->isWidgetType()) {
		QWidget *pw = static_cast<QWidget *>(parent);
		return pw->style()->pixelMetric(pm, 0, pw);
	} else {
		return static_cast<QLayout *>(parent)->spacing();
	}
}