Added initial implementation of loading element effect.

Telegram/SourceFiles/ui/effects/loading_element.cpp

@@ -0,0 +1,142 @@
+/*
+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/loading_element.h"
+
+#include "ui/effects/glare.h"
+
+#include "base/object_ptr.h"
+#include "styles/palette.h"
+#include "styles/style_basic.h"
+#include "styles/style_widgets.h"
+#include "base/random.h"
+#include "ui/painter.h"
+#include "ui/rp_widget.h"
+
+namespace Ui {
+namespace {
+
+class LoadingElement {
+public:
+	LoadingElement() = default;
+
+	[[nodiscard]] virtual int height() const = 0;
+	virtual void paint(QPainter &p, int width) = 0;
+};
+
+class LoadingText final : public LoadingElement {
+public:
+	LoadingText(const style::FlatLabel &st);
+
+	[[nodiscard]] int height() const override;
+	void paint(QPainter &p, int width) override;
+
+private:
+	const style::FlatLabel &_st;
+
+};
+
+LoadingText::LoadingText(const style::FlatLabel &st) : _st(st) {
+}
+
+int LoadingText::height() const {
+	return _st.style.lineHeight;
+}
+
+void LoadingText::paint(QPainter &p, int width) {
+	auto hq = PainterHighQualityEnabler(p);
+
+	p.setPen(Qt::NoPen);
+
+	p.setBrush(st::dialogsDateFg);
+	const auto h = _st.style.font->ascent;
+	p.drawRoundedRect(
+		0,
+		height() - h - (height() - _st.style.font->height),
+		width,
+		h,
+		h / 2,
+		h / 2);
+}
+
+} // namespace
+
+object_ptr<Ui::RpWidget> CreateLoadingTextWidget(
+		not_null<Ui::RpWidget*> parent,
+		const style::FlatLabel &st,
+		int lines,
+		rpl::producer<bool> rtl) {
+	auto widget = object_ptr<Ui::RpWidget>(parent);
+	const auto raw = widget.data();
+
+	struct State {
+		GlareEffect glare;
+		Ui::Animations::Simple animation;
+		int lastLineWidth = 0;
+		rpl::variable<bool> rtl;
+	};
+
+	const auto state = widget->lifetime().make_state<State>();
+	state->rtl = std::move(rtl);
+	state->rtl.value(
+	) | rpl::start_with_next([=] { raw->update(); }, raw->lifetime());
+	raw->resize(raw->width(), LoadingText(st).height() * lines);
+
+	const auto draw = [=](QPainter &p) {
+		auto loading = LoadingText(st);
+		const auto countRows = lines;
+		for (auto i = 0; i < countRows; i++) {
+			const auto w = (i == countRows - 1)
+				? state->lastLineWidth
+				: raw->width();
+			loading.paint(p, w);
+			p.translate(0, loading.height());
+		}
+		p.resetTransform();
+
+		auto &_glare = state->glare;
+		if (_glare.glare.birthTime) {
+			const auto progress = _glare.progress(crl::now());
+			const auto x = (-_glare.width)
+				+ (raw->width() + _glare.width * 2) * progress;
+			const auto h = raw->height();
+
+			p.drawTiledPixmap(x, 0, _glare.width, h, _glare.pixmap, 0, 0);
+		}
+	};
+
+	widget->paintRequest(
+	) | rpl::start_with_next([=](const QRect &r) {
+		auto p = QPainter(raw);
+		if (state->rtl.current()) {
+			const auto r = raw->rect();
+			p.translate(r.center());
+			p.scale(-1., 1.);
+			p.translate(-r.center());
+		}
+		draw(p);
+	}, widget->lifetime());
+
+	constexpr auto kTimeout = crl::time(1000);
+	constexpr auto kDuration = crl::time(1000);
+	widget->widthValue(
+	) | rpl::start_with_next([=](int width) {
+		state->glare.width = width;
+		state->glare.validate(
+			st::dialogsBg->c,
+			[=] { raw->update(); },
+			kTimeout,
+			kDuration);
+		if (width) {
+			state->lastLineWidth = (width / 4) + base::RandomIndex(width / 2);
+		}
+	}, widget->lifetime());
+
+	return widget;
+}
+
+} // namespace Ui

Telegram/SourceFiles/ui/effects/loading_element.h

@@ -0,0 +1,27 @@
+/*
+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
+*/
+#pragma once
+
+template <typename Object>
+class object_ptr;
+
+namespace style {
+struct FlatLabel;
+} // namespace style
+
+namespace Ui {
+
+class RpWidget;
+
+object_ptr<Ui::RpWidget> CreateLoadingTextWidget(
+	not_null<Ui::RpWidget*> parent,
+	const style::FlatLabel &st,
+	int lines,
+	rpl::producer<bool> rtl);
+
+} // namespace Ui

Telegram/cmake/td_ui.cmake

@@ -236,6 +236,8 @@ PRIVATE
     ui/effects/fireworks_animation.h
     ui/effects/glare.cpp
     ui/effects/glare.h
+    ui/effects/loading_element.cpp
+    ui/effects/loading_element.h
     ui/effects/premium_graphics.cpp
     ui/effects/premium_graphics.h
     ui/effects/premium_stars.cpp