tdesktop/Telegram/SourceFiles/ui/effects/premium_graphics.cpp

/*
This file is part of Telegram Desktop,
the official desktop application for the Telegram messaging service.

For license and copyright information please follow this link:
https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
*/
#include "ui/effects/premium_graphics.h"

#include "lang/lang_keys.h"
#include "ui/abstract_button.h"
#include "ui/effects/animations.h"
#include "ui/effects/gradient.h"
#include "ui/effects/numbers_animation.h"
#include "ui/text/text_utilities.h"
#include "ui/layers/generic_box.h"
#include "ui/text/text_options.h"
#include "ui/widgets/checkbox.h"
#include "ui/wrap/padding_wrap.h"
#include "ui/wrap/vertical_layout.h"
#include "styles/style_premium.h"
#include "styles/style_boxes.h"
#include "styles/style_settings.h"
#include "styles/style_layers.h"
#include "styles/style_widgets.h"
#include "styles/style_window.h"

#include <QtGui/QBrush>

namespace Ui {
namespace Premium {
namespace {

using TextFactory = Fn<QString(int)>;

constexpr auto kBubbleRadiusSubtractor = 2;
constexpr auto kDeflectionSmall = 20.;
constexpr auto kDeflection = 30.;

constexpr auto kStepBeforeDeflection = 0.75;
constexpr auto kStepAfterDeflection = kStepBeforeDeflection
	+ (1. - kStepBeforeDeflection) / 2.;

[[nodiscard]] TextFactory ProcessTextFactory(
		std::optional<tr::phrase<lngtag_count>> phrase) {
	return phrase
		? TextFactory([=](int n) { return (*phrase)(tr::now, lt_count, n); })
		: TextFactory([=](int n) { return QString::number(n); });
}

[[nodiscard]] QLinearGradient ComputeGradient(
		not_null<QWidget*> content,
		int left,
		int width) {

	// Take a full width of parent box without paddings.
	const auto fullGradientWidth = content->parentWidget()->width();
	auto fullGradient = QLinearGradient(0, 0, fullGradientWidth, 0);
	fullGradient.setStops(ButtonGradientStops());

	auto gradient = QLinearGradient(0, 0, width, 0);
	const auto fullFinal = float64(fullGradient.finalStop().x());
	left += ((fullGradientWidth - content->width()) / 2);
	gradient.setColorAt(
		.0,
		anim::gradient_color_at(fullGradient, left / fullFinal));
	gradient.setColorAt(
		1.,
		anim::gradient_color_at(fullGradient, (left + width) / fullFinal));

	return gradient;
}

class PartialGradient final {
public:
	PartialGradient(int from, int to, QGradientStops stops);

	[[nodiscard]] QLinearGradient compute(int position, int size) const;

private:
	const int _from;
	const int _to;
	QLinearGradient _gradient;

};

PartialGradient::PartialGradient(int from, int to, QGradientStops stops)
: _from(from)
, _to(to)
, _gradient(0, 0, 0, to - from) {
	_gradient.setStops(std::move(stops));
}

QLinearGradient PartialGradient::compute(int position, int size) const {
	const auto pointTop = position - _from;
	const auto pointBottom = pointTop + size;
	const auto ratioTop = pointTop / float64(_to - _from);
	const auto ratioBottom = pointBottom / float64(_to - _from);

	auto resultGradient = QLinearGradient(
		QPointF(),
		QPointF(0, pointBottom - pointTop));

	resultGradient.setColorAt(
		.0,
		anim::gradient_color_at(_gradient, ratioTop));
	resultGradient.setColorAt(
		.1,
		anim::gradient_color_at(_gradient, ratioBottom));
	return resultGradient;
}

class Bubble final {
public:
	using EdgeProgress = float64;

	Bubble(
		Fn<void()> updateCallback,
		TextFactory textFactory,
		const style::icon *icon,
		bool premiumPossible);

	[[nodiscard]] int counter() const;
	[[nodiscard]] int height() const;
	[[nodiscard]] int width() const;
	[[nodiscard]] int bubbleRadius() const;
	[[nodiscard]] int countMaxWidth(int maxCounter) const;

	void setCounter(int value);
	void setTailEdge(EdgeProgress edge);
	void paintBubble(Painter &p, const QRect &r, const QBrush &brush);

	[[nodiscard]] rpl::producer<> widthChanges() const;

private:
	[[nodiscard]] int filledWidth() const;

	const Fn<void()> _updateCallback;
	const TextFactory _textFactory;

	const style::font &_font;
	const style::margins &_padding;
	const style::icon *_icon;
	NumbersAnimation _numberAnimation;
	const QSize _tailSize;
	const int _height;
	const int _textTop;
	const bool _premiumPossible;

	int _counter = -1;
	EdgeProgress _tailEdge = 0.;

	rpl::event_stream<> _widthChanges;

};

Bubble::Bubble(
	Fn<void()> updateCallback,
	TextFactory textFactory,
	const style::icon *icon,
	bool premiumPossible)
: _updateCallback(std::move(updateCallback))
, _textFactory(std::move(textFactory))
, _font(st::premiumBubbleFont)
, _padding(st::premiumBubblePadding)
, _icon(icon)
, _numberAnimation(_font, _updateCallback)
, _tailSize(st::premiumBubbleTailSize)
, _height(st::premiumBubbleHeight + _tailSize.height())
, _textTop((_height - _tailSize.height() - _font->height) / 2)
, _premiumPossible(premiumPossible) {
	_numberAnimation.setDisabledMonospace(true);
	_numberAnimation.setWidthChangedCallback([=] {
		_widthChanges.fire({});
	});
	_numberAnimation.setText(_textFactory(0), 0);
	_numberAnimation.finishAnimating();
}

int Bubble::counter() const {
	return _counter;
}

int Bubble::height() const {
	return _height;
}

int Bubble::bubbleRadius() const {
	return (_height - _tailSize.height()) / 2 - kBubbleRadiusSubtractor;
}

int Bubble::filledWidth() const {
	return _padding.left()
		+ _icon->width()
		+ st::premiumBubbleTextSkip
		+ _padding.right();
}

int Bubble::width() const {
	return filledWidth() + _numberAnimation.countWidth();
}

int Bubble::countMaxWidth(int maxCounter) const {
	auto numbers = Ui::NumbersAnimation(_font, [] {});
	numbers.setDisabledMonospace(true);
	numbers.setDuration(0);
	numbers.setText(_textFactory(0), 0);
	numbers.setText(_textFactory(maxCounter), maxCounter);
	numbers.finishAnimating();
	return filledWidth() + numbers.maxWidth();
}

void Bubble::setCounter(int value) {
	if (_counter != value) {
		_counter = value;
		_numberAnimation.setText(_textFactory(_counter), _counter);
	}
}

void Bubble::setTailEdge(EdgeProgress edge) {
	_tailEdge = std::clamp(edge, 0., 1.);
}

void Bubble::paintBubble(Painter &p, const QRect &r, const QBrush &brush) {
	if (_counter < 0) {
		return;
	}

	const auto penWidth = st::premiumBubblePenWidth;
	const auto penWidthHalf = penWidth / 2;
	const auto bubbleRect = r - style::margins(
		penWidthHalf,
		penWidthHalf,
		penWidthHalf,
		_tailSize.height() + penWidthHalf);
	{
		const auto radius = bubbleRadius();
		auto pathTail = QPainterPath();

		const auto tailWHalf = _tailSize.width() / 2.;
		const auto progress = _tailEdge;

		const auto tailTop = bubbleRect.y() + bubbleRect.height();
		const auto tailLeftFull = bubbleRect.x()
			+ (bubbleRect.width() * 0.5)
			- tailWHalf;
		const auto tailLeft = bubbleRect.x()
			+ (bubbleRect.width() * 0.5 * (progress + 1.))
			- tailWHalf;
		const auto tailCenter = tailLeft + tailWHalf;
		const auto tailRight = [&] {
			const auto max = bubbleRect.x() + bubbleRect.width();
			const auto right = tailLeft + _tailSize.width();
			const auto bottomMax = max - radius;
			return (right > bottomMax)
				? std::max(float64(tailCenter), float64(bottomMax))
				: right;
		}();
		if (_premiumPossible) {
			pathTail.moveTo(tailLeftFull, tailTop);
			pathTail.lineTo(tailLeft, tailTop);
			pathTail.lineTo(tailCenter, tailTop + _tailSize.height());
			pathTail.lineTo(tailRight, tailTop);
			pathTail.lineTo(tailRight, tailTop - radius);
			pathTail.moveTo(tailLeftFull, tailTop);
		}
		auto pathBubble = QPainterPath();
		pathBubble.setFillRule(Qt::WindingFill);
		pathBubble.addRoundedRect(bubbleRect, radius, radius);

		PainterHighQualityEnabler hq(p);
		p.setPen(QPen(
			brush,
			penWidth,
			Qt::SolidLine,
			Qt::RoundCap,
			Qt::RoundJoin));
		p.setBrush(brush);
		p.drawPath(pathTail + pathBubble);
	}
	p.setPen(st::activeButtonFg);
	p.setFont(_font);
	const auto iconLeft = r.x() + _padding.left();
	_icon->paint(
		p,
		iconLeft,
		bubbleRect.y() + (bubbleRect.height() - _icon->height()) / 2,
		bubbleRect.width());
	_numberAnimation.paint(
		p,
		iconLeft + _icon->width() + st::premiumBubbleTextSkip,
		r.y() + _textTop,
		width() / 2);
}

rpl::producer<> Bubble::widthChanges() const {
	return _widthChanges.events();
}

class BubbleWidget final : public Ui::RpWidget {
public:
	BubbleWidget(
		not_null<Ui::RpWidget*> parent,
		TextFactory textFactory,
		int current,
		int maxCounter,
		bool premiumPossible,
		rpl::producer<> showFinishes,
		const style::icon *icon);

protected:
	void paintEvent(QPaintEvent *e) override;

private:
	const int _currentCounter;
	const int _maxCounter;
	Bubble _bubble;
	const int _maxBubbleWidth;
	const bool _premiumPossible;

	Ui::Animations::Simple _appearanceAnimation;
	QSize _spaceForDeflection;

	QLinearGradient _cachedGradient;

	float64 _deflection;

	bool _ignoreDeflection = false;
	float64 _stepBeforeDeflection;
	float64 _stepAfterDeflection;

};

BubbleWidget::BubbleWidget(
	not_null<Ui::RpWidget*> parent,
	TextFactory textFactory,
	int current,
	int maxCounter,
	bool premiumPossible,
	rpl::producer<> showFinishes,
	const style::icon *icon)
: RpWidget(parent)
, _currentCounter(current)
, _maxCounter(maxCounter)
, _bubble([=] { update(); }, std::move(textFactory), icon, premiumPossible)
, _maxBubbleWidth(_bubble.countMaxWidth(_maxCounter))
, _premiumPossible(premiumPossible)
, _deflection(kDeflection)
, _stepBeforeDeflection(kStepBeforeDeflection)
, _stepAfterDeflection(kStepAfterDeflection) {
	const auto resizeTo = [=](int w, int h) {
		_deflection = (w > st::premiumBubbleWidthLimit)
			? kDeflectionSmall
			: kDeflection;
		_spaceForDeflection = QSize(
			st::premiumBubbleSkip,
			st::premiumBubbleSkip);
		resize(QSize(w, h) + _spaceForDeflection);
	};

	resizeTo(_bubble.width(), _bubble.height());
	_bubble.widthChanges(
	) | rpl::start_with_next([=] {
		resizeTo(_bubble.width(), _bubble.height());
	}, lifetime());

	const auto moveEndPoint = _currentCounter / float64(_maxCounter);
	const auto computeLeft = [=](float64 pointRatio, float64 animProgress) {
		const auto &padding = st::boxRowPadding;
		const auto halfWidth = (_maxBubbleWidth / 2);
		const auto left = padding.left();
		const auto right = padding.right();
		return ((parent->width() - left - right)
				* pointRatio
				* animProgress)
			- halfWidth
			+ left;
	};

	std::move(
		showFinishes
	) | rpl::take(1) | rpl::start_with_next([=] {
		const auto computeEdge = [=] {
			return parent->width()
				- st::boxRowPadding.right()
				- _maxBubbleWidth;
		};
		const auto checkBubbleEdges = [&]() -> Bubble::EdgeProgress {
			const auto finish = computeLeft(moveEndPoint, 1.);
			const auto edge = computeEdge();
			return (finish >= edge)
				? (finish - edge) / (_maxBubbleWidth / 2.)
				: 0.;
		};
		const auto bubbleEdge = checkBubbleEdges();
		_ignoreDeflection = bubbleEdge;
		if (_ignoreDeflection) {
			_stepBeforeDeflection = 1.;
			_stepAfterDeflection = 1.;
		}

		_appearanceAnimation.start([=](float64 value) {
			const auto moveProgress = std::clamp(
				(value / _stepBeforeDeflection),
				0.,
				1.);
			const auto counterProgress = std::clamp(
				(value / _stepAfterDeflection),
				0.,
				1.);
			moveToLeft(
				computeLeft(moveEndPoint, moveProgress)
					- (_maxBubbleWidth / 2.) * bubbleEdge,
				0);

			const auto counter = int(0 + counterProgress * _currentCounter);
			// if (!(counter % 4) || counterProgress > 0.8) {
				_bubble.setCounter(counter);
			// }

			const auto edgeProgress = value * bubbleEdge;
			_bubble.setTailEdge(edgeProgress);
			update();
		},
		0.,
		1.,
		st::premiumBubbleSlideDuration
			* (_ignoreDeflection ? kStepBeforeDeflection : 1.),
		anim::easeOutCirc);
	}, lifetime());
}

void BubbleWidget::paintEvent(QPaintEvent *e) {
	if (_bubble.counter() <= 0) {
		return;
	}

	Painter p(this);

	const auto padding = QMargins(
		0,
		_spaceForDeflection.height(),
		_spaceForDeflection.width(),
		0);
	const auto bubbleRect = rect() - padding;

	if (_appearanceAnimation.animating()) {
		auto gradient = ComputeGradient(
			parentWidget(),
			x(),
			bubbleRect.width());
		_cachedGradient = std::move(gradient);

		const auto progress = _appearanceAnimation.value(1.);
		const auto scaleProgress = std::clamp(
			(progress / _stepBeforeDeflection),
			0.,
			1.);
		const auto scale = scaleProgress;
		const auto rotationProgress = std::clamp(
			(progress - _stepBeforeDeflection) / (1. - _stepBeforeDeflection),
			0.,
			1.);
		const auto rotationProgressReverse = std::clamp(
			(progress - _stepAfterDeflection) / (1. - _stepAfterDeflection),
			0.,
			1.);

		const auto offsetX = bubbleRect.x() + bubbleRect.width() / 2;
		const auto offsetY = bubbleRect.y() + bubbleRect.height();
		p.translate(offsetX, offsetY);
		p.scale(scale, scale);
		if (!_ignoreDeflection) {
			p.rotate(rotationProgress * _deflection
				- rotationProgressReverse * _deflection);
		}
		p.translate(-offsetX, -offsetY);
	}

	_bubble.paintBubble(
		p,
		bubbleRect,
		_premiumPossible ? QBrush(_cachedGradient) : st::windowBgActive->b);
}

class Line final : public Ui::RpWidget {
public:
	Line(
		not_null<Ui::RpWidget*> parent,
		int max,
		TextFactory textFactory,
		int min);
	Line(not_null<Ui::RpWidget*> parent, QString max, QString min);

	void setColorOverride(QBrush brush);

protected:
	void paintEvent(QPaintEvent *event) override;

private:
	void recache(const QSize &s);

	int _leftWidth = 0;
	int _rightWidth = 0;

	QPixmap _leftPixmap;
	QPixmap _rightPixmap;

	Ui::Text::String _leftText;
	Ui::Text::String _rightText;
	Ui::Text::String _rightLabel;
	Ui::Text::String _leftLabel;

	std::optional<QBrush> _overrideBrush;

};

Line::Line(
	not_null<Ui::RpWidget*> parent,
	int max,
	TextFactory textFactory,
	int min)
: Line(
	parent,
	max ? textFactory(max) : QString(),
	min ? textFactory(min) : QString()) {
}

Line::Line(not_null<Ui::RpWidget*> parent, QString max, QString min)
: Ui::RpWidget(parent)
, _leftText(st::semiboldTextStyle, tr::lng_premium_free(tr::now))
, _rightText(st::semiboldTextStyle, tr::lng_premium(tr::now))
, _rightLabel(st::semiboldTextStyle, max)
, _leftLabel(st::semiboldTextStyle, min) {
	resize(width(), st::requestsAcceptButton.height);

	sizeValue(
	) | rpl::start_with_next([=](const QSize &s) {
		if (s.isEmpty()) {
			return;
		}
		_leftWidth = (s.width() / 2);
		_rightWidth = (s.width() - _leftWidth);
		recache(s);
		update();
	}, lifetime());
}

void Line::setColorOverride(QBrush brush) {
	if (brush.style() == Qt::NoBrush) {
		_overrideBrush = std::nullopt;
	} else {
		_overrideBrush = brush;
	}
}

void Line::paintEvent(QPaintEvent *event) {
	Painter p(this);

	p.drawPixmap(0, 0, _leftPixmap);
	p.drawPixmap(_leftWidth, 0, _rightPixmap);

	p.setFont(st::normalFont);

	const auto textPadding = st::premiumLineTextSkip;
	const auto textTop = (height() - _leftText.minHeight()) / 2;

	p.setPen(st::windowFg);
	_leftLabel.drawRight(
		p,
		textPadding,
		textTop,
		_leftWidth - textPadding,
		_leftWidth,
		style::al_right);
	_leftText.drawLeft(
		p,
		textPadding,
		textTop,
		_leftWidth - textPadding,
		_leftWidth);

	p.setPen(st::activeButtonFg);
	_rightLabel.drawRight(
		p,
		textPadding,
		textTop,
		_rightWidth - textPadding,
		width(),
		style::al_right);
	_rightText.drawLeftElided(
		p,
		_leftWidth + textPadding,
		textTop,
		_rightWidth - _rightLabel.countWidth(_rightWidth) - textPadding * 2,
		_rightWidth);
}

void Line::recache(const QSize &s) {
	const auto r = QRect(0, 0, _leftWidth, s.height());
	auto pixmap = QPixmap(r.size() * style::DevicePixelRatio());
	pixmap.setDevicePixelRatio(style::DevicePixelRatio());
	pixmap.fill(Qt::transparent);

	auto pathRound = QPainterPath();
	pathRound.addRoundedRect(r, st::buttonRadius, st::buttonRadius);

	{
		auto leftPixmap = pixmap;
		Painter p(&leftPixmap);
		PainterHighQualityEnabler hq(p);
		auto pathRect = QPainterPath();
		auto halfRect = r;
		halfRect.setLeft(r.center().x());
		pathRect.addRect(halfRect);

		p.fillPath(pathRound + pathRect, st::windowShadowFgFallback);

		_leftPixmap = std::move(leftPixmap);
	}
	{
		auto rightPixmap = pixmap;
		Painter p(&rightPixmap);
		PainterHighQualityEnabler hq(p);
		auto pathRect = QPainterPath();
		auto halfRect = r;
		halfRect.setRight(r.center().x());
		pathRect.addRect(halfRect);

		if (_overrideBrush) {
			p.fillPath(pathRound + pathRect, *_overrideBrush);
		} else {
			auto gradient = ComputeGradient(
				this,
				(_leftPixmap.width() / style::DevicePixelRatio()) + r.x(),
				r.width());
			p.fillPath(pathRound + pathRect, QBrush(std::move(gradient)));
		}

		_rightPixmap = std::move(rightPixmap);
	}
}

} // namespace

void AddBubbleRow(
		not_null<Ui::VerticalLayout*> parent,
		rpl::producer<> showFinishes,
		int min,
		int current,
		int max,
		bool premiumPossible,
		std::optional<tr::phrase<lngtag_count>> phrase,
		const style::icon *icon) {
	const auto container = parent->add(
		object_ptr<Ui::FixedHeightWidget>(parent, 0));
	const auto bubble = Ui::CreateChild<BubbleWidget>(
		container,
		ProcessTextFactory(phrase),
		current,
		max,
		premiumPossible,
		std::move(showFinishes),
		icon);
	rpl::combine(
		container->sizeValue(),
		bubble->sizeValue()
	) | rpl::start_with_next([=](const QSize &parentSize, const QSize &size) {
		container->resize(parentSize.width(), size.height());
	}, bubble->lifetime());
}

void AddLimitRow(
		not_null<Ui::VerticalLayout*> parent,
		QString max,
		QString min) {
	parent->add(object_ptr<Line>(parent, max, min), st::boxRowPadding);
}

void AddLimitRow(
		not_null<Ui::VerticalLayout*> parent,
		int max,
		std::optional<tr::phrase<lngtag_count>> phrase,
		int min) {
	const auto factory = ProcessTextFactory(phrase);
	AddLimitRow(
		parent,
		max ? factory(max) : QString(),
		min ? factory(min) : QString());
}

void AddAccountsRow(
		not_null<Ui::VerticalLayout*> parent,
		AccountsRowArgs &&args) {
	const auto container = parent->add(
		object_ptr<Ui::FixedHeightWidget>(parent, st::premiumAccountsHeight),
		st::boxRowPadding);

	struct Account {
		not_null<Ui::AbstractButton*> widget;
		Ui::RoundImageCheckbox checkbox;
		Ui::Text::String name;
		QPixmap badge;
	};
	struct State {
		std::vector<Account> accounts;
	};
	const auto state = container->lifetime().make_state<State>();
	const auto group = args.group;

	const auto imageRadius = args.st.imageRadius;
	const auto checkSelectWidth = args.st.selectWidth;
	const auto nameFg = args.stNameFg;

	const auto cacheBadge = [=](int center) {
		const auto &padding = st::premiumAccountsLabelPadding;
		const auto size = st::premiumAccountsLabelSize
			+ QSize(
				padding.left() + padding.right(),
				padding.top() + padding.bottom());
		auto badge = QPixmap(size * style::DevicePixelRatio());
		badge.setDevicePixelRatio(style::DevicePixelRatio());
		badge.fill(Qt::transparent);

		Painter p(&badge);
		PainterHighQualityEnabler hq(p);

		p.setPen(Qt::NoPen);
		const auto rectOut = QRect(QPoint(), size);
		const auto rectIn = rectOut - padding;

		const auto radius = st::premiumAccountsLabelRadius;
		p.setBrush(st::premiumButtonFg);
		p.drawRoundedRect(rectOut, radius, radius);

		const auto left = center - rectIn.width() / 2;
		p.setBrush(QBrush(ComputeGradient(container, left, rectIn.width())));
		p.drawRoundedRect(rectIn, radius / 2, radius / 2);

		p.setPen(st::premiumButtonFg);
		p.setFont(st::semiboldFont);
		p.drawText(rectIn, u"+1"_q, style::al_center);

		return badge;
	};

	for (auto &entry : args.entries) {
		const auto widget = Ui::CreateChild<Ui::AbstractButton>(container);
		auto name = Ui::Text::String(imageRadius * 2);
		name.setText(args.stName, entry.name, Ui::NameTextOptions());
		state->accounts.push_back(Account{
			.widget = widget,
			.checkbox = Ui::RoundImageCheckbox(
				args.st,
				[=] { widget->update(); },
				base::take(entry.paintRoundImage)),
			.name = std::move(name),
		});
		const auto index = int(state->accounts.size()) - 1;
		state->accounts[index].checkbox.setChecked(
			index == group->value(),
			anim::type::instant);

		widget->paintRequest(
		) | rpl::start_with_next([=] {
			Painter p(widget);
			const auto width = widget->width();
			const auto photoLeft = (width - (imageRadius * 2)) / 2;
			const auto photoTop = checkSelectWidth;
			const auto &account = state->accounts[index];
			account.checkbox.paint(p, photoLeft, photoTop, width);

			const auto &badgeSize = account.badge.size()
				/ style::DevicePixelRatio();
			p.drawPixmap(
				(width - badgeSize.width()) / 2,
				photoTop + (imageRadius * 2) - badgeSize.height() / 2,
				account.badge);

			p.setPen(nameFg);
			p.setBrush(Qt::NoBrush);
			account.name.drawLeftElided(
				p,
				0,
				photoTop + imageRadius * 2 + st::premiumAccountsNameTop,
				width,
				width,
				2,
				style::al_top,
				0,
				-1,
				0,
				true);
		}, widget->lifetime());

		widget->setClickedCallback([=] {
			group->setValue(index);
		});
	}

	container->sizeValue(
	) | rpl::start_with_next([=](const QSize &size) {
		const auto count = state->accounts.size();
		const auto columnWidth = size.width() / count;
		for (auto i = 0; i < count; i++) {
			auto &account = state->accounts[i];
			account.widget->resize(columnWidth, size.height());
			const auto left = columnWidth * i;
			account.widget->moveToLeft(left, 0);
			account.badge = cacheBadge(left + columnWidth / 2);

			const auto photoWidth = ((imageRadius + checkSelectWidth) * 2);
			account.checkbox.setColorOverride(QBrush(
				ComputeGradient(
					container,
					left + (columnWidth - photoWidth) / 2,
					photoWidth)));
		}
	}, container->lifetime());

	group->setChangedCallback([=](int value) {
		for (auto i = 0; i < state->accounts.size(); i++) {
			state->accounts[i].checkbox.setChecked(i == value);
		}
	});
}

QGradientStops LimitGradientStops() {
	return {
		{ 0.0, st::premiumButtonBg1->c },
		{ .25, st::premiumButtonBg1->c },
		{ .85, st::premiumButtonBg2->c },
		{ 1.0, st::premiumButtonBg3->c },
	};
}

QGradientStops ButtonGradientStops() {
	return {
		{ 0., st::premiumButtonBg1->c },
		{ 0.6, st::premiumButtonBg2->c },
		{ 1., st::premiumButtonBg3->c },
	};
}

QGradientStops LockGradientStops() {
	return ButtonGradientStops();
}

QGradientStops FullHeightGradientStops() {
	return {
		{ 0.0, st::premiumIconBg1->c },
		{ .28, st::premiumIconBg2->c },
		{ .55, st::premiumButtonBg2->c },
		{ 1.0, st::premiumButtonBg1->c },
	};
}

QGradientStops GiftGradientStops() {
	return {
		{ 0., st::premiumButtonBg1->c },
		{ 1., st::premiumButtonBg2->c },
	};
}

void ShowListBox(
		not_null<Ui::GenericBox*> box,
		std::vector<ListEntry> entries) {

	const auto &stLabel = st::defaultFlatLabel;
	const auto &titlePadding = st::settingsPremiumPreviewTitlePadding;
	const auto &descriptionPadding = st::settingsPremiumPreviewAboutPadding;

	auto lines = std::vector<Line*>();
	lines.reserve(int(entries.size()));

	const auto content = box->verticalLayout();
	for (auto &entry : entries) {
		content->add(
			object_ptr<Ui::FlatLabel>(
				content,
				base::take(entry.subtitle) | rpl::map(Ui::Text::Bold),
				stLabel),
			titlePadding);
		content->add(
			object_ptr<Ui::FlatLabel>(
				content,
				base::take(entry.description),
				st::boxDividerLabel),
			descriptionPadding);

		const auto limitRow = content->add(
			object_ptr<Line>(
				content,
				entry.rightNumber,
				TextFactory([=, text = ProcessTextFactory(std::nullopt)](
						int n) {
					if (entry.customRightText && (n == entry.rightNumber)) {
						return *entry.customRightText;
					} else {
						return text(n);
					}
				}),
				entry.leftNumber),
			st::settingsPremiumPreviewLinePadding);
		lines.push_back(limitRow);
	}

	content->resizeToWidth(content->height());

	// Color lines.
	Assert(lines.size() > 2);
	const auto from = lines.front()->y();
	const auto to = lines.back()->y() + lines.back()->height();

	const auto partialGradient = [&] {
		auto stops = Ui::Premium::FullHeightGradientStops();
		// Reverse.
		for (auto &stop : stops) {
			stop.first = std::abs(stop.first - 1.);
		}
		return PartialGradient(from, to, std::move(stops));
	}();

	for (auto i = 0; i < int(lines.size()); i++) {
		const auto &line = lines[i];

		const auto brush = QBrush(
			partialGradient.compute(line->y(), line->height()));
		line->setColorOverride(brush);
	}
	box->addSkip(st::settingsPremiumPreviewLinePadding.bottom());

	box->setTitle(tr::lng_premium_summary_subtitle_double_limits());
	box->setWidth(st::boxWideWidth);
}

void AddGiftOptions(
		not_null<Ui::VerticalLayout*> parent,
		std::shared_ptr<Ui::RadiobuttonGroup> group,
		std::vector<GiftInfo> gifts) {

	struct Edges {
		Ui::RpWidget *top = nullptr;
		Ui::RpWidget *bottom = nullptr;
	};
	const auto edges = parent->lifetime().make_state<Edges>();
	struct Animation {
		int nowIndex = 0;
		Ui::Animations::Simple animation;
	};
	const auto animation = parent->lifetime().make_state<Animation>();

	const auto stops = GiftGradientStops();

	const auto addRow = [&](const GiftInfo &info, int index) {
		const auto row = parent->add(
			object_ptr<Ui::AbstractButton>(parent),
			st::premiumGiftRowPaddings);
		row->resize(row->width(), st::premiumGiftRowHeight);
		{
			if (!index) {
				edges->top = row;
			}
			edges->bottom = row;
		}

		const auto &stCheckbox = st::defaultBoxCheckbox;
		const auto radio = Ui::CreateChild<Ui::Radiobutton>(
			row,
			group,
			index,
			QString(),
			stCheckbox);
		radio->setAttribute(Qt::WA_TransparentForMouseEvents);

		row->sizeValue(
		) | rpl::start_with_next([=, margins = stCheckbox.margin](
				const QSize &s) {
			const auto radioHeight = radio->height()
				- margins.top()
				- margins.bottom();
			radio->moveToLeft(
				st::premiumGiftRowMargins.left(),
				(s.height() - radioHeight) / 2);
		}, radio->lifetime());

		row->paintRequest(
		) | rpl::start_with_next([=](const QRect &r) {
			Painter p(row);
			PainterHighQualityEnabler hq(p);

			p.fillRect(r, Qt::transparent);

			const auto left = st::premiumGiftRowTextLeft;
			const auto borderWidth = st::premiumGiftRowBorderWidth;
			const auto halfHeight = row->height() / 2;

			const auto titleFont = st::semiboldFont;
			p.setFont(titleFont);
			p.setPen(st::boxTextFg);
			p.drawText(
				left,
				st::premiumGiftRowSubtitleTop + titleFont->ascent,
				info.duration);

			const auto discountFont = st::windowFiltersButton.badgeStyle.font;
			const auto discountWidth = discountFont->width(info.discount);
			const auto &discountMargins = st::premiumGiftRowBadgeMargins;
			const auto discountRect = QRect(
				left,
				halfHeight + discountMargins.top(),
				discountWidth
					+ discountMargins.left()
					+ discountMargins.right(),
				st::premiumGiftRowBadgeHeight);
			{
				const auto from = edges->top->y();
				const auto to = edges->bottom->y() + edges->bottom->height();
				auto partialGradient = PartialGradient(from, to, stops);

				p.setPen(Qt::NoPen);
				p.setBrush(partialGradient.compute(row->y(), row->height()));
				const auto round = st::premiumGiftRowBadgeRadius;
				p.drawRoundedRect(discountRect, round, round);
			}

			if (animation->nowIndex == index) {
				const auto progress = animation->animation.value(1.);
				const auto w = row->width();
				auto gradient = QLinearGradient(w - w * progress, 0, w * 2, 0);
				gradient.setSpread(QGradient::Spread::RepeatSpread);
				gradient.setStops(stops);
				const auto pen = QPen(QBrush(gradient), borderWidth);
				p.setPen(pen);
				p.setBrush(Qt::NoBrush);
				const auto borderRect = row->rect()
					- QMargins(
						pen.width() / 2,
						pen.width() / 2,
						pen.width() / 2,
						pen.width() / 2);
				const auto round = st::premiumGiftRowBorderRadius;
				p.drawRoundedRect(borderRect, round, round);
			}

			p.setPen(st::boxBg);
			p.setFont(discountFont);
			p.drawText(discountRect, info.discount, style::al_center);

			const auto perRect = QMargins(0, 0, row->width(), 0)
				+ discountRect.translated(
					discountRect.width() + discountMargins.left(),
					0);
			p.setPen(st::windowSubTextFg);
			p.setFont(st::shareBoxListItem.nameStyle.font);
			p.drawText(perRect, info.perMonth, style::al_left);

			const auto totalRect = row->rect()
				- QMargins(0, 0, st::premiumGiftRowMargins.right(), 0);
			p.setFont(st::normalFont);
			p.drawText(totalRect, info.total, style::al_right);
		}, row->lifetime());

		row->setClickedCallback([=, duration = st::defaultCheck.duration] {
			group->setValue(index);
			animation->nowIndex = group->value();
			animation->animation.stop();
			animation->animation.start(
				[=] { parent->update(); },
				0.,
				1.,
				duration);
		});

	};
	for (auto i = 0; i < gifts.size(); i++) {
		addRow(gifts[i], i);
	}

	parent->resizeToWidth(parent->height());
	parent->update();
}

} // namespace Premium
} // namespace Ui