Add Ui::PathShiftGradient effect.

CMakeLists.txt

@@ -51,6 +51,8 @@ PRIVATE
     ui/effects/numbers_animation.h
     ui/effects/panel_animation.cpp
     ui/effects/panel_animation.h
+    ui/effects/path_shift_gradient.cpp
+    ui/effects/path_shift_gradient.h
     ui/effects/radial_animation.cpp
     ui/effects/radial_animation.h
     ui/effects/ripple_animation.cpp

ui/effects/path_shift_gradient.cpp

@@ -0,0 +1,175 @@
+// This file is part of Desktop App Toolkit,
+// a set of libraries for developing nice desktop applications.
+//
+// For license and copyright information please follow this link:
+// https://github.com/desktop-app/legal/blob/master/LEGAL
+//
+#include "ui/effects/path_shift_gradient.h"
+
+#include "base/call_delayed.h"
+#include "ui/effects/animations.h"
+
+namespace Ui {
+namespace {
+
+constexpr auto kSlideDuration = crl::time(1000);
+constexpr auto kWaitDuration = crl::time(1000);
+constexpr auto kFullDuration = kSlideDuration + kWaitDuration;
+
+} // namespace
+
+struct PathShiftGradient::AnimationData {
+	Ui::Animations::Simple animation;
+	base::flat_set<not_null<PathShiftGradient*>> active;
+	bool scheduled = false;
+};
+
+std::weak_ptr<PathShiftGradient::AnimationData> PathShiftGradient::Animation;
+
+PathShiftGradient::PathShiftGradient(
+	const style::color &bg,
+	const style::color &fg,
+	Fn<void()> animationCallback)
+: _bg(bg)
+, _fg(fg)
+, _animationCallback(std::move(animationCallback)) {
+	refreshColors();
+	style::PaletteChanged(
+	) | rpl::start_with_next([=] {
+		refreshColors();
+	}, _lifetime);
+}
+
+PathShiftGradient::~PathShiftGradient() {
+	if (const auto strong = _animation.get()) {
+		strong->active.erase(this);
+	}
+}
+
+void PathShiftGradient::overrideColors(
+		const style::color &bg,
+		const style::color &fg) {
+	_colorsOverriden = true;
+	refreshColors(bg, fg);
+}
+
+void PathShiftGradient::clearOverridenColors() {
+	if (!_colorsOverriden) {
+		return;
+	}
+	_colorsOverriden = false;
+	refreshColors();
+}
+
+void PathShiftGradient::startFrame(
+		int viewportLeft,
+		int viewportWidth,
+		int gradientWidth) {
+	_viewportLeft = viewportLeft;
+	_viewportWidth = viewportWidth;
+	_gradientWidth = gradientWidth;
+	_geometryUpdated = false;
+}
+
+void PathShiftGradient::updateGeometry() {
+	if (_geometryUpdated) {
+		return;
+	}
+	_geometryUpdated = true;
+	const auto now = crl::now();
+	const auto period = now % kFullDuration;
+	if (period >= kSlideDuration) {
+		_gradientEnabled = false;
+		return;
+	}
+	const auto progress = period / float64(kSlideDuration);
+	_gradientStart = anim::interpolate(
+		_viewportLeft - _gradientWidth,
+		_viewportLeft + _viewportWidth,
+		progress);
+	_gradientFinalStop = _gradientStart + _gradientWidth;
+	_gradientEnabled = true;
+}
+
+bool PathShiftGradient::paint(Fn<bool(const Background&)> painter) {
+	updateGeometry();
+	if (_gradientEnabled) {
+		_gradient.setStart(_gradientStart, 0);
+		_gradient.setFinalStop(_gradientFinalStop, 0);
+	}
+	const auto background = _gradientEnabled
+		? Background(&_gradient)
+		: _bgOverride
+		? *_bgOverride
+		: _bg;
+	if (!painter(background)) {
+		return false;
+	}
+	activateAnimation();
+	return true;
+}
+
+void PathShiftGradient::activateAnimation() {
+	if (_animationActive) {
+		return;
+	}
+	_animationActive = true;
+	if (!_animation) {
+		_animation = Animation.lock();
+		if (!_animation) {
+			_animation = std::make_shared<AnimationData>();
+			Animation = _animation;
+		}
+	}
+	const auto raw = _animation.get();
+	if (_animationCallback) {
+		raw->active.emplace(this);
+	}
+
+	const auto globalCallback = [] {
+		const auto strong = Animation.lock();
+		if (!strong) {
+			return;
+		}
+		strong->scheduled = false;
+		while (!strong->active.empty()) {
+			const auto entry = strong->active.back();
+			strong->active.erase(strong->active.end() - 1);
+			entry->_animationActive = false;
+			entry->_animationCallback();
+		}
+	};
+
+	const auto now = crl::now();
+	const auto period = now % kFullDuration;
+	if (period >= kSlideDuration) {
+		const auto tillWaitFinish = kFullDuration - period;
+		if (!raw->scheduled) {
+			raw->scheduled = true;
+			raw->animation.stop();
+			base::call_delayed(tillWaitFinish, globalCallback);
+		}
+	} else {
+		const auto tillSlideFinish = kSlideDuration - period;
+		if (!raw->animation.animating()) {
+			raw->animation.start(globalCallback, 0., 1., tillSlideFinish);
+		}
+	}
+}
+
+void PathShiftGradient::refreshColors() {
+	refreshColors(_bg, _fg);
+}
+
+void PathShiftGradient::refreshColors(
+		const style::color &bg,
+		const style::color &fg) {
+	_gradient.setStops({
+		{ 0., bg->c },
+		{ 0.5, fg->c },
+		{ 1., bg->c },
+	});
+	_bgOverride = _colorsOverriden ? &bg : nullptr;
+}
+
+} // namespace Ui

ui/effects/path_shift_gradient.h

@@ -0,0 +1,64 @@
+// This file is part of Desktop App Toolkit,
+// a set of libraries for developing nice desktop applications.
+//
+// For license and copyright information please follow this link:
+// https://github.com/desktop-app/legal/blob/master/LEGAL
+//
+#pragma once
+
+#include "ui/style/style_core_types.h"
+
+#include <QtGui/QLinearGradient>
+
+namespace Ui {
+
+class PathShiftGradient final {
+public:
+	PathShiftGradient(
+		const style::color &bg,
+		const style::color &fg,
+		Fn<void()> animationCallback);
+	~PathShiftGradient();
+
+	void startFrame(
+		int viewportLeft,
+		int viewportWidth,
+		int gradientWidth);
+
+	void overrideColors(const style::color &bg, const style::color &fg);
+	void clearOverridenColors();
+
+	using Background = std::variant<QLinearGradient*, style::color>;
+	bool paint(Fn<bool(const Background&)> painter);
+
+private:
+	struct AnimationData;
+
+	void refreshColors();
+	void refreshColors(const style::color &bg, const style::color &fg);
+	void updateGeometry();
+	void activateAnimation();
+
+	static std::weak_ptr<AnimationData> Animation;
+
+	const style::color &_bg;
+	const style::color &_fg;
+	const style::color *_bgOverride = nullptr;
+	QLinearGradient _gradient;
+	std::shared_ptr<AnimationData> _animation;
+	const Fn<void()> _animationCallback;
+	int _viewportLeft = 0;
+	int _viewportWidth = 0;
+	int _gradientWidth = 0;
+	int _gradientStart = 0;
+	int _gradientFinalStop = 0;
+	bool _gradientEnabled = false;
+	bool _geometryUpdated = false;
+	bool _animationActive = false;
+	bool _colorsOverriden = false;
+
+	rpl::lifetime _lifetime;
+
+};
+
+} // namespace Ui