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Telegram/lib_ui/ui/click_handler.h

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+// 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 "base/basic_types.h"
+#include "base/flat_map.h"
+
+#include <QtCore/QVariant>
+
+class ClickHandler;
+using ClickHandlerPtr = std::shared_ptr<ClickHandler>;
+
+struct ClickContext {
+	Qt::MouseButton button = Qt::LeftButton;
+	QVariant other;
+};
+
+class ClickHandlerHost {
+protected:
+	virtual void clickHandlerActiveChanged(const ClickHandlerPtr &action, bool active) {
+	}
+	virtual void clickHandlerPressedChanged(const ClickHandlerPtr &action, bool pressed) {
+	}
+	virtual ~ClickHandlerHost() = 0;
+	friend class ClickHandler;
+
+};
+
+enum class EntityType : uchar;
+class ClickHandler {
+public:
+	virtual ~ClickHandler() {
+	}
+
+	virtual void onClick(ClickContext context) const = 0;
+
+	// Some sort of `id`, for text links contains urls.
+	virtual QString url() const {
+		return QString();
+	}
+
+	// What text to show in a tooltip when mouse is over that click handler as a link in Text.
+	virtual QString tooltip() const {
+		return QString();
+	}
+
+	// What to drop in the input fields when dragging that click handler as a link from Text.
+	virtual QString dragText() const {
+		return QString();
+	}
+
+	// Copy to clipboard support.
+	virtual QString copyToClipboardText() const {
+		return QString();
+	}
+	virtual QString copyToClipboardContextItemText() const {
+		return QString();
+	}
+
+	// Entities in text support.
+	struct TextEntity {
+		EntityType type = EntityType();
+		QString data;
+	};
+	virtual TextEntity getTextEntity() const;
+
+	void setProperty(int id, QVariant value);
+	[[nodiscard]] const QVariant &property(int id) const;
+
+	// This method should be called on mouse over a click handler.
+	// It returns true if the active handler was changed or false otherwise.
+	static bool setActive(const ClickHandlerPtr &p, ClickHandlerHost *host = nullptr);
+
+	// This method should be called when mouse leaves the host.
+	// It returns true if the active handler was changed or false otherwise.
+	static bool clearActive(ClickHandlerHost *host = nullptr);
+
+	// This method should be called on mouse press event.
+	static void pressed();
+
+	// This method should be called on mouse release event.
+	// The activated click handler (if any) is returned.
+	static ClickHandlerPtr unpressed();
+
+	static ClickHandlerPtr getActive();
+	static ClickHandlerPtr getPressed();
+
+	static bool showAsActive(const ClickHandlerPtr &p);
+	static bool showAsPressed(const ClickHandlerPtr &p);
+	static void hostDestroyed(ClickHandlerHost *host);
+
+private:
+	static ClickHandlerHost *_activeHost;
+	static ClickHandlerHost *_pressedHost;
+
+	base::flat_map<int, QVariant> _properties;
+
+};
+
+class LeftButtonClickHandler : public ClickHandler {
+public:
+	void onClick(ClickContext context) const override final {
+		if (context.button == Qt::LeftButton) {
+			onClickImpl();
+		}
+	}
+
+protected:
+	virtual void onClickImpl() const = 0;
+
+};
+
+class GenericClickHandler : public ClickHandler {
+public:
+	GenericClickHandler(Fn<void()> handler)
+	: _handler([handler = std::move(handler)](ClickContext) { handler(); }) {
+	}
+	GenericClickHandler(Fn<void(ClickContext)> handler)
+	: _handler(std::move(handler)) {
+	}
+	void onClick(ClickContext context) const override {
+		if (_handler) {
+			_handler(context);
+		}
+	}
+
+private:
+	Fn<void(ClickContext)> _handler;
+
+};
+
+class LambdaClickHandler : public GenericClickHandler {
+public:
+	using GenericClickHandler::GenericClickHandler;
+
+	void onClick(ClickContext context) const override final {
+		if (context.button == Qt::LeftButton) {
+			GenericClickHandler::onClick(std::move(context));
+		}
+	}
+
+};
+
+void ActivateClickHandler(
+	not_null<QWidget*> guard,
+	ClickHandlerPtr handler,
+	ClickContext context);
+void ActivateClickHandler(
+	not_null<QWidget*> guard,
+	ClickHandlerPtr handler,
+	Qt::MouseButton button);