Add tooltips for buttons, labels, icons, pie charts, sliders, and progress barstooltip

17 files changed, 443 insertions, 70 deletions

diff --git a/extension/src/openvic-extension/classes/GFXPieChartTexture.cpp b/extension/src/openvic-extension/classes/GFXPieChartTexture.cpp
index 417566d..5d955a3 100644
--- a/extension/src/openvic-extension/classes/GFXPieChartTexture.cpp
+++ b/extension/src/openvic-extension/classes/GFXPieChartTexture.cpp
@@ -7,6 +7,7 @@
 
 using namespace godot;
 using namespace OpenVic;
+using namespace OpenVic::Utilities::literals;
 
 StringName const& GFXPieChartTexture::_slice_identifier_key() {
 	static const StringName slice_identifier_key = "identifier";
@@ -21,7 +22,35 @@ StringName const& GFXPieChartTexture::_slice_weight_key() {
 	return slice_weight_key;
 }
 
-static constexpr float TWO_PI = 2.0f * std::numbers::pi_v<float>;
+GFXPieChartTexture::slice_t const* GFXPieChartTexture::get_slice(Vector2 const& position) const {
+	if (slices.empty() || position.length_squared() > 1.0_real) {
+		return nullptr;
+	}
+
+	static constexpr float TWO_PI = 2.0f * std::numbers::pi_v<float>;
+
+	/* Calculate the anti-clockwise angle between the point and the centre of the image.
+	 * The y coordinate is negated as the image coordinate system's y increases downwards. */
+	float theta = atan2(-position.y, position.x);
+	if (theta < 0.0f) {
+		theta += TWO_PI;
+	}
+
+	/* Rescale angle so that total_weight is a full rotation. */
+	theta *= total_weight / TWO_PI;
+
+	/* Find the slice theta lies in. */
+	for (slice_t const& slice : slices) {
+		theta -= slice.weight;
+
+		if (theta <= 0.0f) {
+			return &slice;
+		}
+	}
+
+	/* Default to the first slice in case theta never reaches 0 due to floating point inaccuracy. */
+	return &slices.front();
+}
 
 Error GFXPieChartTexture::_generate_pie_chart_image() {
 	ERR_FAIL_NULL_V(gfx_pie_chart, FAILED);
@@ -30,60 +59,37 @@ Error GFXPieChartTexture::_generate_pie_chart_image() {
 		vformat("Invalid GFX::PieChart size for GFXPieChartTexture - %d", gfx_pie_chart->get_size())
 	);
 
-	const int32_t pie_chart_size = 2 * gfx_pie_chart->get_size();
+	const int32_t pie_chart_radius = gfx_pie_chart->get_size();
+	const int32_t pie_chart_diameter = 2 * pie_chart_radius;
 
 	/* Whether we've already set the ImageTexture to an image of the right dimensions,
 	 * and so can update it without creating and setting a new image, or not. */
-	const bool can_update = pie_chart_image.is_valid() && pie_chart_image->get_width() == pie_chart_size
-		&& pie_chart_image->get_height() == pie_chart_size;
+	const bool can_update = pie_chart_image.is_valid() && pie_chart_image->get_width() == pie_chart_diameter
+		&& pie_chart_image->get_height() == pie_chart_diameter;
 
 	if (!can_update) {
-		pie_chart_image = Image::create(pie_chart_size, pie_chart_size, false, Image::FORMAT_RGBA8);
+		pie_chart_image = Image::create(pie_chart_diameter, pie_chart_diameter, false, Image::FORMAT_RGBA8);
 		ERR_FAIL_NULL_V(pie_chart_image, FAILED);
 	}
 
 	static const Color background_colour { 0.0f, 0.0f, 0.0f, 0.0f };
 
 	if (!slices.empty()) {
-		const float pie_chart_radius = gfx_pie_chart->get_size();
-
-		const Vector2 centre_translation = Vector2 { 0.5f, 0.5f } - static_cast<Vector2>(pie_chart_image->get_size()) * 0.5f;
-
-		for (Vector2i point { 0, 0 }; point.y < pie_chart_image->get_height(); ++point.y) {
-
-			for (point.x = 0; point.x < pie_chart_image->get_width(); ++point.x) {
-
-				const Vector2 offset = centre_translation + point;
-
-				if (offset.length() <= pie_chart_radius) {
-
-					/* Calculate the anti-clockwise angle between the point and the centre of the image.
-					 * The y coordinate is negated as the image coordinate system's y increases downwards. */
-					float theta = atan2(-offset.y, offset.x);
-					if (theta < 0.0f) {
-						theta += TWO_PI;
-					}
-
-					/* Rescale angle so that total_weight is a full rotation. */
-					theta *= total_weight / TWO_PI;
+		for (Vector2i point { 0, 0 }; point.y < pie_chart_diameter; ++point.y) {
 
-					/* Default to the first colour in case theta never reaches 0 due to floating point inaccuracy. */
-					Color colour = slices.front().first;
+			for (point.x = 0; point.x < pie_chart_diameter; ++point.x) {
 
-					/* Find the slice theta lies in. */
-					for (slice_t const& slice : slices) {
-						theta -= slice.second;
+				Vector2 offset = point;
+				// Move to the centre of the pixel
+				offset += Vector2 { 0.5_real, 0.5_real };
+				// Normalise to [0, 2]
+				offset /= pie_chart_radius;
+				// Translate to [-1, 1]
+				offset -= Vector2 { 1.0_real, 1.0_real };
 
-						if (theta <= 0.0f) {
-							colour = slice.first;
-							break;
-						}
-					}
+				slice_t const* slice = get_slice(offset);
 
-					pie_chart_image->set_pixelv(point, colour);
-				} else {
-					pie_chart_image->set_pixelv(point, background_colour);
-				}
+				pie_chart_image->set_pixelv(point, slice != nullptr ? slice->colour : background_colour);
 			}
 		}
 	} else {
@@ -107,12 +113,15 @@ Error GFXPieChartTexture::set_slices_array(godot_pie_chart_data_t const& new_sli
 	for (int32_t i = 0; i < new_slices.size(); ++i) {
 		Dictionary const& slice_dict = new_slices[i];
 		ERR_CONTINUE_MSG(
-			!slice_dict.has(_slice_colour_key()) || !slice_dict.has(_slice_weight_key()),
+			!slice_dict.has(_slice_identifier_key()) || !slice_dict.has(_slice_colour_key())
+				|| !slice_dict.has(_slice_weight_key()),
 			vformat("Invalid slice keys at index %d", i)
 		);
-		const slice_t slice = std::make_pair(slice_dict[_slice_colour_key()], slice_dict[_slice_weight_key()]);
-		if (slice.second > 0.0f) {
-			total_weight += slice.second;
+		const slice_t slice {
+			slice_dict[_slice_identifier_key()], slice_dict[_slice_colour_key()], slice_dict[_slice_weight_key()]
+		};
+		if (slice.weight > 0.0f) {
+			total_weight += slice.weight;
 			slices.push_back(slice);
 		}
 	}
diff --git a/extension/src/openvic-extension/classes/GFXPieChartTexture.hpp b/extension/src/openvic-extension/classes/GFXPieChartTexture.hpp
index 9642f4e..3610efb 100644
--- a/extension/src/openvic-extension/classes/GFXPieChartTexture.hpp
+++ b/extension/src/openvic-extension/classes/GFXPieChartTexture.hpp
@@ -10,11 +10,17 @@ namespace OpenVic {
 	class GFXPieChartTexture : public godot::ImageTexture {
 		GDCLASS(GFXPieChartTexture, godot::ImageTexture)
 
-		using slice_t = std::pair<godot::Color, float>;
+	public:
+		struct slice_t {
+			godot::String name;
+			godot::Color colour;
+			float weight;
+		};
 
+	private:
 		GFX::PieChart const* PROPERTY(gfx_pie_chart);
 		std::vector<slice_t> slices;
-		float total_weight;
+		float PROPERTY(total_weight);
 		godot::Ref<godot::Image> pie_chart_image;
 
 		static godot::StringName const& _slice_identifier_key();
@@ -29,6 +35,9 @@ namespace OpenVic {
 	public:
 		GFXPieChartTexture();
 
+		// Position must be centred and normalised so that coords are in [-1, 1].
+		slice_t const* get_slice(godot::Vector2 const& position) const;
+
 		using godot_pie_chart_data_t = godot::TypedArray<godot::Dictionary>;
 
 		/* Set slices given an Array of Dictionaries, each with the following key-value entries:
diff --git a/extension/src/openvic-extension/classes/GUIButton.cpp b/extension/src/openvic-extension/classes/GUIButton.cpp
index 323b03c..e35d67a 100644
--- a/extension/src/openvic-extension/classes/GUIButton.cpp
+++ b/extension/src/openvic-extension/classes/GUIButton.cpp
@@ -10,7 +10,17 @@
 using namespace godot;
 using namespace OpenVic;
 
-void GUIButton::_bind_methods() {}
+GUI_TOOLTIP_IMPLEMENTATIONS(GUIButton)
+
+void GUIButton::_bind_methods() {
+	GUI_TOOLTIP_BIND_METHODS(GUIButton)
+}
+
+void GUIButton::_notification(int what) {
+	_tooltip_notification(what);
+}
+
+GUIButton::GUIButton() : tooltip_active { false } {}
 
 Error GUIButton::set_gfx_button_state_having_texture(Ref<GFXButtonStateHavingTexture> const& texture) {
 	ERR_FAIL_NULL_V(texture, FAILED);
diff --git a/extension/src/openvic-extension/classes/GUIButton.hpp b/extension/src/openvic-extension/classes/GUIButton.hpp
index 4e53125..3873a4d 100644
--- a/extension/src/openvic-extension/classes/GUIButton.hpp
+++ b/extension/src/openvic-extension/classes/GUIButton.hpp
@@ -5,17 +5,24 @@
 #include <openvic-simulation/interface/GFXSprite.hpp>
 
 #include "openvic-extension/classes/GFXButtonStateTexture.hpp"
+#include "openvic-extension/classes/GUIHasTooltip.hpp"
 
 namespace OpenVic {
 	class GUIButton : public godot::Button {
 		GDCLASS(GUIButton, godot::Button)
 
+		GUI_TOOLTIP_DEFINITIONS
+
 	protected:
 		static void _bind_methods();
 
+		void _notification(int what);
+
 		godot::Error set_gfx_button_state_having_texture(godot::Ref<GFXButtonStateHavingTexture> const& texture);
 
 	public:
+		GUIButton();
+
 		godot::Error set_gfx_font(GFX::Font const* gfx_font);
 	};
 }
diff --git a/extension/src/openvic-extension/classes/GUIHasTooltip.hpp b/extension/src/openvic-extension/classes/GUIHasTooltip.hpp
new file mode 100644
index 0000000..22413ec
--- /dev/null
+++ b/extension/src/openvic-extension/classes/GUIHasTooltip.hpp
@@ -0,0 +1,121 @@
+#pragma once
+
+#include <godot_cpp/classes/control.hpp>
+#include <godot_cpp/variant/string.hpp>
+#include <godot_cpp/variant/utility_functions.hpp>
+#include <godot_cpp/variant/vector2.hpp>
+
+#include <openvic-simulation/utility/Getters.hpp>
+
+#include "openvic-extension/singletons/MenuSingleton.hpp"
+#include "openvic-extension/utility/ClassBindings.hpp"
+#include "openvic-extension/utility/Utilities.hpp"
+
+/* To add tooltip functionality to a class:
+ *  - the class must be derived from Control.
+ *  - add GUI_TOOLTIP_DEFINITIONS to the class definition, bearing in mind that it leaves visibility as private.
+ *  - add GUI_TOOLTIP_IMPLEMENTATIONS(CLASS) to the class' source file.
+ *  - add GUI_TOOLTIP_BIND_METHODS(CLASS) to the class' _bind_methods implementation.
+ *  - call _tooltip_notification from the class' _notification method.
+ *  - initialise tooltip_active to false in the class' constructor. */
+
+#define GUI_TOOLTIP_DEFINITIONS \
+	public: \
+		void set_tooltip_string_and_substitution_dict( \
+			godot::String const& new_tooltip_string, godot::Dictionary const& new_tooltip_substitution_dict \
+		); \
+		void set_tooltip_string(godot::String const& new_tooltip_string); \
+		void set_tooltip_substitution_dict(godot::Dictionary const& new_tooltip_substitution_dict); \
+		void clear_tooltip(); \
+	private: \
+		godot::String PROPERTY(tooltip_string); \
+		godot::Dictionary PROPERTY(tooltip_substitution_dict); \
+		bool PROPERTY_CUSTOM_PREFIX(tooltip_active, is); \
+		void _tooltip_notification(int what); \
+		void _set_tooltip_active(bool new_tooltip_active); \
+		void _set_tooltip_visibility(bool visible);
+
+#define GUI_TOOLTIP_IMPLEMENTATIONS(CLASS) \
+	void CLASS::set_tooltip_string_and_substitution_dict( \
+		String const& new_tooltip_string, Dictionary const& new_tooltip_substitution_dict \
+	) { \
+		if (get_mouse_filter() == MOUSE_FILTER_IGNORE) { \
+			UtilityFunctions::push_error("Tooltips won't work for \"", get_name(), "\" as it has MOUSE_FILTER_IGNORE"); \
+		} \
+		if (tooltip_string != new_tooltip_string || tooltip_substitution_dict != new_tooltip_substitution_dict) { \
+			tooltip_string = new_tooltip_string; \
+			tooltip_substitution_dict = new_tooltip_substitution_dict; \
+			if (tooltip_active) { \
+				_set_tooltip_visibility(!tooltip_string.is_empty()); \
+			} \
+		} \
+	} \
+	void CLASS::set_tooltip_string(String const& new_tooltip_string) { \
+		if (get_mouse_filter() == MOUSE_FILTER_IGNORE) { \
+			UtilityFunctions::push_error("Tooltips won't work for \"", get_name(), "\" as it has MOUSE_FILTER_IGNORE"); \
+		} \
+		if (tooltip_string != new_tooltip_string) { \
+			tooltip_string = new_tooltip_string; \
+			if (tooltip_active) { \
+				_set_tooltip_visibility(!tooltip_string.is_empty()); \
+			} \
+		} \
+	} \
+	void CLASS::set_tooltip_substitution_dict(Dictionary const& new_tooltip_substitution_dict) { \
+		if (get_mouse_filter() == MOUSE_FILTER_IGNORE) { \
+			UtilityFunctions::push_error("Tooltips won't work for \"", get_name(), "\" as it has MOUSE_FILTER_IGNORE"); \
+		} \
+		if (tooltip_substitution_dict != new_tooltip_substitution_dict) { \
+			tooltip_substitution_dict = new_tooltip_substitution_dict; \
+			if (tooltip_active) { \
+				_set_tooltip_visibility(!tooltip_string.is_empty()); \
+			} \
+		} \
+	} \
+	void CLASS::clear_tooltip() { \
+		set_tooltip_string_and_substitution_dict({}, {}); \
+	} \
+	void CLASS::_tooltip_notification(int what) { \
+		if (what == NOTIFICATION_MOUSE_ENTER_SELF) { \
+			_set_tooltip_active(true); \
+		} else if (what == NOTIFICATION_MOUSE_EXIT_SELF) { \
+			_set_tooltip_active(false); \
+		} \
+	} \
+	void CLASS::_set_tooltip_active(bool new_tooltip_active) { \
+		if (tooltip_active != new_tooltip_active) { \
+			tooltip_active = new_tooltip_active; \
+			if (!tooltip_string.is_empty()) { \
+				_set_tooltip_visibility(tooltip_active); \
+			} \
+		} \
+	} \
+	void CLASS::_set_tooltip_visibility(bool visible) { \
+		MenuSingleton* menu_singleton = MenuSingleton::get_singleton(); \
+		ERR_FAIL_NULL(menu_singleton); \
+		if (visible) { \
+			menu_singleton->show_control_tooltip(tooltip_string, tooltip_substitution_dict, this); \
+		} else { \
+			menu_singleton->hide_tooltip(); \
+		} \
+	}
+
+#define GUI_TOOLTIP_BIND_METHODS(CLASS) \
+	OV_BIND_METHOD(CLASS::get_tooltip_string); \
+	OV_BIND_METHOD(CLASS::set_tooltip_string, { "new_tooltip_string" }); \
+	OV_BIND_METHOD(CLASS::get_tooltip_substitution_dict); \
+	OV_BIND_METHOD(CLASS::set_tooltip_substitution_dict, { "new_tooltip_substitution_dict" }); \
+	OV_BIND_METHOD( \
+		CLASS::set_tooltip_string_and_substitution_dict, { "new_tooltip_string", "new_tooltip_substitution_dict" } \
+	); \
+	OV_BIND_METHOD(CLASS::clear_tooltip); \
+	OV_BIND_METHOD(CLASS::is_tooltip_active); \
+	ADD_PROPERTY( \
+		PropertyInfo(Variant::STRING, "tooltip_string", PROPERTY_HINT_MULTILINE_TEXT), \
+		"set_tooltip_string", "get_tooltip_string" \
+	); \
+	ADD_PROPERTY( \
+		PropertyInfo(Variant::DICTIONARY, "tooltip_substitution_dict"), \
+		"set_tooltip_substitution_dict", "get_tooltip_substitution_dict" \
+	); \
+	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "tooltip_active"), "", "is_tooltip_active");
diff --git a/extension/src/openvic-extension/classes/GUILabel.cpp b/extension/src/openvic-extension/classes/GUILabel.cpp
index 9fd6b60..732dec2 100644
--- a/extension/src/openvic-extension/classes/GUILabel.cpp
+++ b/extension/src/openvic-extension/classes/GUILabel.cpp
@@ -14,7 +14,30 @@ using namespace OpenVic::Utilities::literals;
 
 static constexpr int32_t DEFAULT_FONT_SIZE = 16;
 
+GUI_TOOLTIP_IMPLEMENTATIONS(GUILabel)
+
+String const& GUILabel::get_colour_marker() {
+	static const String COLOUR_MARKER = String::chr(0xA7); // §
+	return COLOUR_MARKER;
+}
+
+String const& GUILabel::get_currency_marker() {
+	static const String CURRENCY_MARKER = String::chr(0xA4); // ¤
+	return CURRENCY_MARKER;
+}
+
+String const& GUILabel::get_substitution_marker() {
+	static const String SUBSTITUTION_MARKER = String::chr(0x24); // $
+	return SUBSTITUTION_MARKER;
+}
+
 void GUILabel::_bind_methods() {
+	GUI_TOOLTIP_BIND_METHODS(GUILabel)
+
+	OV_BIND_SMETHOD(get_colour_marker);
+	OV_BIND_SMETHOD(get_currency_marker);
+	OV_BIND_SMETHOD(get_substitution_marker);
+
 	OV_BIND_METHOD(GUILabel::clear);
 	OV_BIND_METHOD(GUILabel::get_gui_text_name);
 
@@ -80,6 +103,8 @@ void GUILabel::_bind_methods() {
 }
 
 void GUILabel::_notification(int what) {
+	_tooltip_notification(what);
+
 	switch (what) {
 	case NOTIFICATION_RESIZED:
 	case NOTIFICATION_TRANSLATION_CHANGED: {
@@ -146,7 +171,8 @@ void GUILabel::_notification(int what) {
 }
 
 GUILabel::GUILabel()
-  : gui_text { nullptr },
+  : tooltip_active { false },
+	gui_text { nullptr },
 	text {},
 	substitution_dict {},
 	horizontal_alignment { HORIZONTAL_ALIGNMENT_LEFT },
@@ -454,29 +480,30 @@ void GUILabel::_update_lines() {
 }
 
 String GUILabel::generate_substituted_text(String const& base_text) const {
-	static const String SUBSTITUTION_MARKER = String::chr(0x24); // $
-
 	String result;
 	int64_t start_pos = 0;
 	int64_t marker_start_pos;
 
-	while ((marker_start_pos = base_text.find(SUBSTITUTION_MARKER, start_pos)) != -1) {
+	while ((marker_start_pos = base_text.find(get_substitution_marker(), start_pos)) != -1) {
 		result += base_text.substr(start_pos, marker_start_pos - start_pos);
 
-		int64_t marker_end_pos = base_text.find(SUBSTITUTION_MARKER, marker_start_pos + SUBSTITUTION_MARKER.length());
+		int64_t marker_end_pos = base_text.find(
+			get_substitution_marker(), marker_start_pos + get_substitution_marker().length()
+		);
 		if (marker_end_pos == -1) {
 			marker_end_pos = base_text.length();
 		}
 
 		String key = base_text.substr(
-			marker_start_pos + SUBSTITUTION_MARKER.length(), marker_end_pos - marker_start_pos - SUBSTITUTION_MARKER.length()
+			marker_start_pos + get_substitution_marker().length(),
+			marker_end_pos - marker_start_pos - get_substitution_marker().length()
 		);
 		String value = substitution_dict.get(key, String {});
 
 		// Use the un-substituted key if no value is found or the value is empty
 		result += value.is_empty() ? key : is_auto_translating() ? tr(value) : value;
 
-		start_pos = marker_end_pos + SUBSTITUTION_MARKER.length();
+		start_pos = marker_end_pos + get_substitution_marker().length();
 	}
 
 	if (start_pos < base_text.length()) {
@@ -489,25 +516,23 @@ String GUILabel::generate_substituted_text(String const& base_text) const {
 std::pair<String, GUILabel::colour_instructions_t> GUILabel::generate_display_text_and_colour_instructions(
 	String const& substituted_text
 ) const {
-	static const String COLOUR_MARKER = String::chr(0xA7); // §
-
 	String result;
 	colour_instructions_t colour_instructions;
 	int64_t start_pos = 0;
 	int64_t marker_pos;
 
-	while ((marker_pos = substituted_text.find(COLOUR_MARKER, start_pos)) != -1) {
+	while ((marker_pos = substituted_text.find(get_colour_marker(), start_pos)) != -1) {
 		result += substituted_text.substr(start_pos, marker_pos - start_pos);
 
-		if (marker_pos + COLOUR_MARKER.length() < substituted_text.length()) {
-			const char32_t colour_code = substituted_text[marker_pos + COLOUR_MARKER.length()];
+		if (marker_pos + get_colour_marker().length() < substituted_text.length()) {
+			const char32_t colour_code = substituted_text[marker_pos + get_colour_marker().length()];
 
 			// Check that the colour code can be safely cast to a char
 			if (colour_code >> sizeof(char) * CHAR_BIT == 0) {
 				colour_instructions.emplace_back(result.length(), static_cast<char>(colour_code));
 			}
 
-			start_pos = marker_pos + COLOUR_MARKER.length() + 1;
+			start_pos = marker_pos + get_colour_marker().length() + 1;
 		} else {
 			return { std::move(result), std::move(colour_instructions) };
 		}
@@ -588,8 +613,6 @@ void GUILabel::separate_lines(
 void GUILabel::separate_currency_segments(
 	String const& string, Color const& colour, line_t& line
 ) const {
-	static const String CURRENCY_MARKER = String::chr(0xA4); // ¤
-
 	const auto push_string_segment = [this, &string, &colour, &line](int64_t start, int64_t end) -> void {
 		String substring = string.substr(start, end - start);
 		const real_t width = get_string_width(substring);
@@ -602,7 +625,7 @@ void GUILabel::separate_currency_segments(
 
 	const real_t currency_width = currency_texture.is_valid() ? currency_texture->get_width() : 0.0_real;
 
-	while ((marker_pos = string.find(CURRENCY_MARKER, start_pos)) != -1) {
+	while ((marker_pos = string.find(get_currency_marker(), start_pos)) != -1) {
 		if (start_pos < marker_pos) {
 			push_string_segment(start_pos, marker_pos);
 		}
@@ -610,7 +633,7 @@ void GUILabel::separate_currency_segments(
 		line.segments.push_back(currency_segment_t {});
 		line.width += currency_width;
 
-		start_pos = marker_pos + CURRENCY_MARKER.length();
+		start_pos = marker_pos + get_currency_marker().length();
 	}
 
 	if (start_pos < string.length()) {
diff --git a/extension/src/openvic-extension/classes/GUILabel.hpp b/extension/src/openvic-extension/classes/GUILabel.hpp
index e0982b2..102ad94 100644
--- a/extension/src/openvic-extension/classes/GUILabel.hpp
+++ b/extension/src/openvic-extension/classes/GUILabel.hpp
@@ -8,11 +8,14 @@
 #include <openvic-simulation/interface/GUI.hpp>
 
 #include "openvic-extension/classes/GFXSpriteTexture.hpp"
+#include "openvic-extension/classes/GUIHasTooltip.hpp"
 
 namespace OpenVic {
 	class GUILabel : public godot::Control {
 		GDCLASS(GUILabel, godot::Control)
 
+		GUI_TOOLTIP_DEFINITIONS
+
 		using colour_instructions_t = std::vector<std::pair<int64_t, char>>;
 
 		GUI::Text const* PROPERTY(gui_text);
@@ -55,6 +58,10 @@ namespace OpenVic {
 		void _notification(int what);
 
 	public:
+		static godot::String const& get_colour_marker();
+		static godot::String const& get_currency_marker();
+		static godot::String const& get_substitution_marker();
+
 		GUILabel();
 
 		/* Reset gui_text to nullptr and reset current text. */
diff --git a/extension/src/openvic-extension/classes/GUIPieChart.cpp b/extension/src/openvic-extension/classes/GUIPieChart.cpp
index a8ed087..0688dd3 100644
--- a/extension/src/openvic-extension/classes/GUIPieChart.cpp
+++ b/extension/src/openvic-extension/classes/GUIPieChart.cpp
@@ -1,11 +1,51 @@
 #include "GUIPieChart.hpp"
 
+#include <godot_cpp/classes/input_event_mouse_motion.hpp>
+
+#include "openvic-extension/classes/GUILabel.hpp"
+#include "openvic-extension/singletons/MenuSingleton.hpp"
 #include "openvic-extension/utility/ClassBindings.hpp"
 
 using namespace godot;
 using namespace OpenVic;
 using namespace OpenVic::Utilities::literals;
 
+void GUIPieChart::_update_tooltip() {
+	MenuSingleton* menu_singleton = MenuSingleton::get_singleton();
+	ERR_FAIL_NULL(menu_singleton);
+
+	if (gfx_pie_chart_texture.is_valid()) {
+		GFXPieChartTexture::slice_t const* slice = gfx_pie_chart_texture->get_slice(tooltip_position);
+
+		if (slice != nullptr) {
+			static const String tooltip_identifier_key = "ID";
+			static const String tooltip_percent_key = "PC";
+			// "§Y$ID$§!: $PC$%"
+			static const String tooltip_string =
+				GUILabel::get_colour_marker() + String { "Y" } + GUILabel::get_substitution_marker() + tooltip_identifier_key
+				+ GUILabel::get_substitution_marker() + GUILabel::get_colour_marker() + "!: "
+				+ GUILabel::get_substitution_marker() + tooltip_percent_key + GUILabel::get_substitution_marker() + "%";
+
+			Dictionary substitution_dict;
+			substitution_dict[tooltip_identifier_key] = slice->name;
+
+			float percent = slice->weight * 100.0f;
+			if (gfx_pie_chart_texture->get_total_weight() > 0.0f) {
+				percent /= gfx_pie_chart_texture->get_total_weight();
+			}
+			substitution_dict[tooltip_percent_key] = Utilities::float_to_string_dp(percent, 2);
+
+			menu_singleton->show_control_tooltip(tooltip_string, substitution_dict, this);
+
+			tooltip_active = true;
+			return;
+		}
+	}
+
+	menu_singleton->hide_tooltip();
+	tooltip_active = false;
+}
+
 void GUIPieChart::_bind_methods() {
 	OV_BIND_METHOD(GUIPieChart::get_gfx_pie_chart_texture);
 	OV_BIND_METHOD(GUIPieChart::set_gfx_pie_chart_name, { "gfx_pie_chart_name" });
@@ -13,6 +53,28 @@ void GUIPieChart::_bind_methods() {
 	OV_BIND_METHOD(GUIPieChart::set_slices_array, { "new_slices" });
 }
 
+static const Vector2 disabled_tooltip_position { -1.0_real, -1.0_real };
+
+void GUIPieChart::_notification(int what) {
+	if (what == NOTIFICATION_MOUSE_EXIT_SELF) {
+		tooltip_position = disabled_tooltip_position;
+
+		_update_tooltip();
+	}
+}
+
+void GUIPieChart::_gui_input(Ref<InputEvent> const& event) {
+	Ref<InputEventMouseMotion> mm = event;
+
+	if (mm.is_valid()) {
+		tooltip_position = mm->get_position() * 2.0_real / get_size() - Vector2 { 1.0_real, 1.0_real };
+
+		_update_tooltip();
+	}
+}
+
+GUIPieChart::GUIPieChart() : tooltip_active { false }, tooltip_position { disabled_tooltip_position } {}
+
 Error GUIPieChart::set_gfx_pie_chart(GFX::PieChart const* gfx_pie_chart) {
 	const bool needs_setting = gfx_pie_chart_texture.is_null();
 
@@ -27,6 +89,10 @@ Error GUIPieChart::set_gfx_pie_chart(GFX::PieChart const* gfx_pie_chart) {
 		set_texture(gfx_pie_chart_texture);
 	}
 
+	if (tooltip_active) {
+		_update_tooltip();
+	}
+
 	return err;
 }
 
@@ -50,6 +116,10 @@ Error GUIPieChart::set_gfx_pie_chart_name(String const& gfx_pie_chart_name) {
 		set_texture(gfx_pie_chart_texture);
 	}
 
+	if (tooltip_active) {
+		_update_tooltip();
+	}
+
 	return err;
 }
 
@@ -59,8 +129,14 @@ String GUIPieChart::get_gfx_pie_chart_name() const {
 	return gfx_pie_chart_texture->get_gfx_pie_chart_name();
 }
 
-Error GUIPieChart::set_slices_array(GFXPieChartTexture::godot_pie_chart_data_t const& new_slices) const {
+Error GUIPieChart::set_slices_array(GFXPieChartTexture::godot_pie_chart_data_t const& new_slices) {
 	ERR_FAIL_NULL_V(gfx_pie_chart_texture, FAILED);
 
-	return gfx_pie_chart_texture->set_slices_array(new_slices);
+	const Error err = gfx_pie_chart_texture->set_slices_array(new_slices);
+
+	if (tooltip_active) {
+		_update_tooltip();
+	}
+
+	return err;
 }
diff --git a/extension/src/openvic-extension/classes/GUIPieChart.hpp b/extension/src/openvic-extension/classes/GUIPieChart.hpp
index 6b4ac87..3356dba 100644
--- a/extension/src/openvic-extension/classes/GUIPieChart.hpp
+++ b/extension/src/openvic-extension/classes/GUIPieChart.hpp
@@ -12,10 +12,21 @@ namespace OpenVic {
 
 		godot::Ref<GFXPieChartTexture> gfx_pie_chart_texture;
 
+		bool tooltip_active;
+		godot::Vector2 tooltip_position;
+
+		void _update_tooltip();
+
 	protected:
 		static void _bind_methods();
 
+		void _notification(int what);
+
 	public:
+		void _gui_input(godot::Ref<godot::InputEvent> const& event) override;
+
+		GUIPieChart();
+
 		godot::Error set_gfx_pie_chart(GFX::PieChart const* gfx_pie_chart);
 
 		godot::Ref<GFXPieChartTexture> get_gfx_pie_chart_texture() const;
@@ -24,6 +35,6 @@ namespace OpenVic {
 
 		godot::String get_gfx_pie_chart_name() const;
 
-		godot::Error set_slices_array(GFXPieChartTexture::godot_pie_chart_data_t const& new_slices) const;
+		godot::Error set_slices_array(GFXPieChartTexture::godot_pie_chart_data_t const& new_slices);
 	};
 }
diff --git a/extension/src/openvic-extension/classes/GUIProgressBar.cpp b/extension/src/openvic-extension/classes/GUIProgressBar.cpp
index 6021746..d13f455 100644
--- a/extension/src/openvic-extension/classes/GUIProgressBar.cpp
+++ b/extension/src/openvic-extension/classes/GUIProgressBar.cpp
@@ -8,7 +8,17 @@
 using namespace godot;
 using namespace OpenVic;
 
-void GUIProgressBar::_bind_methods() {}
+GUI_TOOLTIP_IMPLEMENTATIONS(GUIProgressBar)
+
+void GUIProgressBar::_bind_methods() {
+	GUI_TOOLTIP_BIND_METHODS(GUIProgressBar)
+}
+
+void GUIProgressBar::_notification(int what) {
+	_tooltip_notification(what);
+}
+
+GUIProgressBar::GUIProgressBar() : tooltip_active { false } {}
 
 Error GUIProgressBar::set_gfx_progress_bar(GFX::ProgressBar const* progress_bar) {
 	ERR_FAIL_NULL_V(progress_bar, FAILED);
diff --git a/extension/src/openvic-extension/classes/GUIProgressBar.hpp b/extension/src/openvic-extension/classes/GUIProgressBar.hpp
index 130ac91..11b677a 100644
--- a/extension/src/openvic-extension/classes/GUIProgressBar.hpp
+++ b/extension/src/openvic-extension/classes/GUIProgressBar.hpp
@@ -3,15 +3,22 @@
 #include <godot_cpp/classes/texture_progress_bar.hpp>
 
 #include "openvic-simulation/interface/GFXSprite.hpp"
+#include "openvic-extension/classes/GUIHasTooltip.hpp"
 
 namespace OpenVic {
 	class GUIProgressBar : public godot::TextureProgressBar {
 		GDCLASS(GUIProgressBar, godot::TextureProgressBar)
 
+		GUI_TOOLTIP_DEFINITIONS
+
 	protected:
 		static void _bind_methods();
 
+		void _notification(int what);
+
 	public:
+		GUIProgressBar();
+
 		godot::Error set_gfx_progress_bar(GFX::ProgressBar const* progress_bar);
 	};
 }
diff --git a/extension/src/openvic-extension/classes/GUIScrollbar.cpp b/extension/src/openvic-extension/classes/GUIScrollbar.cpp
index ddcba7c..6e310d7 100644
--- a/extension/src/openvic-extension/classes/GUIScrollbar.cpp
+++ b/extension/src/openvic-extension/classes/GUIScrollbar.cpp
@@ -18,7 +18,11 @@ StringName const& GUIScrollbar::signal_value_changed() {
 	return signal_value_changed;
 }
 
+GUI_TOOLTIP_IMPLEMENTATIONS(GUIScrollbar)
+
 void GUIScrollbar::_bind_methods() {
+	GUI_TOOLTIP_BIND_METHODS(GUIScrollbar)
+
 	OV_BIND_METHOD(GUIScrollbar::emit_value_changed);
 	OV_BIND_METHOD(GUIScrollbar::reset);
 	OV_BIND_METHOD(GUIScrollbar::clear);
@@ -49,7 +53,7 @@ void GUIScrollbar::_bind_methods() {
 	ADD_SIGNAL(MethodInfo(signal_value_changed(), PropertyInfo(Variant::INT, "value")));
 }
 
-GUIScrollbar::GUIScrollbar() {
+GUIScrollbar::GUIScrollbar() : tooltip_active { false } {
 	/* Anything which the constructor might not have default initialised will be set by clear(). */
 	clear();
 }
@@ -587,11 +591,16 @@ void GUIScrollbar::_gui_input(Ref<InputEvent> const& event) {
 			hover_more = !hover_more;
 			queue_redraw();
 		}
+
+		_set_tooltip_active(hover_slider || hover_track || hover_less || hover_more);
+
 		return;
 	}
 }
 
 void GUIScrollbar::_notification(int what) {
+	// GUIScrollbar doesn't use _tooltip_notification, as we don't want to show tooltips when hovering over transparent parts.
+
 	switch (what) {
 	case NOTIFICATION_VISIBILITY_CHANGED:
 	case NOTIFICATION_MOUSE_EXIT: {
@@ -602,6 +611,10 @@ void GUIScrollbar::_notification(int what) {
 		queue_redraw();
 	} break;
 
+	case NOTIFICATION_MOUSE_EXIT_SELF: {
+		_set_tooltip_active(false);
+	} break;
+
 	/* Pressing (and holding) less and more buttons. */
 	case NOTIFICATION_INTERNAL_PHYSICS_PROCESS: {
 		const double delta = get_physics_process_delta_time();
diff --git a/extension/src/openvic-extension/classes/GUIScrollbar.hpp b/extension/src/openvic-extension/classes/GUIScrollbar.hpp
index 16b2e00..d9b22f1 100644
--- a/extension/src/openvic-extension/classes/GUIScrollbar.hpp
+++ b/extension/src/openvic-extension/classes/GUIScrollbar.hpp
@@ -6,11 +6,14 @@
 #include <openvic-simulation/interface/GUI.hpp>
 
 #include "openvic-extension/classes/GFXSpriteTexture.hpp"
+#include "openvic-extension/classes/GUIHasTooltip.hpp"
 
 namespace OpenVic {
 	class GUIScrollbar : public godot::Control {
 		GDCLASS(GUIScrollbar, godot::Control)
 
+		GUI_TOOLTIP_DEFINITIONS
+
 		GUI::Scrollbar const* PROPERTY(gui_scrollbar);
 
 		godot::Ref<GFXSpriteTexture> slider_texture;
@@ -74,6 +77,7 @@ namespace OpenVic {
 
 	protected:
 		static void _bind_methods();
+
 		void _notification(int what);
 
 	public:
diff --git a/extension/src/openvic-extension/classes/GUITextureRect.cpp b/extension/src/openvic-extension/classes/GUITextureRect.cpp
index 13fd3bb..fba9b19 100644
--- a/extension/src/openvic-extension/classes/GUITextureRect.cpp
+++ b/extension/src/openvic-extension/classes/GUITextureRect.cpp
@@ -3,4 +3,14 @@
 using namespace godot;
 using namespace OpenVic;
 
-void GUITextureRect::_bind_methods() {}
+GUI_TOOLTIP_IMPLEMENTATIONS(GUITextureRect)
+
+void GUITextureRect::_bind_methods() {
+	GUI_TOOLTIP_BIND_METHODS(GUITextureRect)
+}
+
+void GUITextureRect::_notification(int what) {
+	_tooltip_notification(what);
+}
+
+GUITextureRect::GUITextureRect() : tooltip_active { false } {}
diff --git a/extension/src/openvic-extension/classes/GUITextureRect.hpp b/extension/src/openvic-extension/classes/GUITextureRect.hpp
index afcf4da..6fc8123 100644
--- a/extension/src/openvic-extension/classes/GUITextureRect.hpp
+++ b/extension/src/openvic-extension/classes/GUITextureRect.hpp
@@ -2,11 +2,20 @@
 
 #include <godot_cpp/classes/texture_rect.hpp>
 
+#include "openvic-extension/classes/GUIHasTooltip.hpp"
+
 namespace OpenVic {
 	class GUITextureRect : public godot::TextureRect {
 		GDCLASS(GUITextureRect, godot::TextureRect)
 
+		GUI_TOOLTIP_DEFINITIONS
+
 	protected:
 		static void _bind_methods();
+
+		void _notification(int what);
+
+	public:
+		GUITextureRect();
 	};
 }
diff --git a/extension/src/openvic-extension/singletons/MenuSingleton.cpp b/extension/src/openvic-extension/singletons/MenuSingleton.cpp
index b95bc15..367462b 100644
--- a/extension/src/openvic-extension/singletons/MenuSingleton.cpp
+++ b/extension/src/openvic-extension/singletons/MenuSingleton.cpp
@@ -30,6 +30,10 @@ StringName const& MenuSingleton::_signal_search_cache_changed() {
 	static const StringName signal_search_cache_changed = "search_cache_changed";
 	return signal_search_cache_changed;
 }
+StringName const& MenuSingleton::_signal_update_tooltip() {
+	static const StringName signal_update_tooltip = "update_tooltip";
+	return signal_update_tooltip;
+}
 
 String MenuSingleton::get_state_name(State const& state) const {
 	StateSet const& state_set = state.get_state_set();
@@ -103,6 +107,16 @@ String MenuSingleton::get_country_adjective(CountryInstance const& country) cons
 }
 
 void MenuSingleton::_bind_methods() {
+	/* TOOLTIP */
+	OV_BIND_METHOD(MenuSingleton::show_tooltip, { "text", "substitution_dict", "position" });
+	OV_BIND_METHOD(MenuSingleton::show_control_tooltip, { "text", "substitution_dict", "control" });
+	OV_BIND_METHOD(MenuSingleton::hide_tooltip);
+
+	ADD_SIGNAL(MethodInfo(
+		_signal_update_tooltip(), PropertyInfo(Variant::STRING, "text"),
+		PropertyInfo(Variant::DICTIONARY, "substitution_dict"), PropertyInfo(Variant::VECTOR2, "position")
+	));
+
 	/* PROVINCE OVERVIEW PANEL */
 	OV_BIND_METHOD(MenuSingleton::get_province_info_from_index, { "index" });
 	OV_BIND_METHOD(MenuSingleton::get_province_building_count);
@@ -205,6 +219,25 @@ MenuSingleton::~MenuSingleton() {
 	singleton = nullptr;
 }
 
+/* TOOLTIP */
+
+void MenuSingleton::show_tooltip(String const& text, Dictionary const& substitution_dict, Vector2 const& position) {
+	emit_signal(_signal_update_tooltip(), text, substitution_dict, position);
+}
+
+void MenuSingleton::show_control_tooltip(String const& text, Dictionary const& substitution_dict, Control const* control) {
+	ERR_FAIL_NULL(control);
+
+	using namespace OpenVic::Utilities::literals;
+	static const Vector2 offset { 0.0_real, 64.0_real };
+
+	show_tooltip(text, substitution_dict, control->get_global_position() + offset);
+}
+
+void MenuSingleton::hide_tooltip() {
+	show_tooltip({}, {}, {});
+}
+
 /* PROVINCE OVERVIEW PANEL */
 
 static TypedArray<Dictionary> _make_buildings_dict_array(
diff --git a/extension/src/openvic-extension/singletons/MenuSingleton.hpp b/extension/src/openvic-extension/singletons/MenuSingleton.hpp
index 190e3ea..022bce5 100644
--- a/extension/src/openvic-extension/singletons/MenuSingleton.hpp
+++ b/extension/src/openvic-extension/singletons/MenuSingleton.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <godot_cpp/classes/control.hpp>
 #include <godot_cpp/classes/image.hpp>
 
 #include <openvic-simulation/pop/Pop.hpp>
@@ -95,6 +96,10 @@ namespace OpenVic {
 		static godot::StringName const& _signal_population_menu_pops_changed();
 		/* Emitted when the collection of possible search results changes. */
 		static godot::StringName const& _signal_search_cache_changed();
+		/* Emitted when the current tooltip changes. Arguments: text (godot::String), substitution_dict (godot::Dictionary),
+		 * position (godot::Vector2). If text is empty then the tooltip will be hidden, otherwise the text will be shown at
+		 * the given position. */
+		static godot::StringName const& _signal_update_tooltip();
 
 		godot::String get_state_name(State const& state) const;
 		godot::String get_country_name(CountryInstance const& country) const;
@@ -110,6 +115,15 @@ namespace OpenVic {
 		MenuSingleton();
 		~MenuSingleton();
 
+		/* TOOLTIP */
+		void show_tooltip(
+			godot::String const& text, godot::Dictionary const& substitution_dict, godot::Vector2 const& position
+		);
+		void show_control_tooltip(
+			godot::String const& text, godot::Dictionary const& substitution_dict, godot::Control const* control
+		);
+		void hide_tooltip();
+
 		/* PROVINCE OVERVIEW PANEL */
 		/* Get info to display in Province Overview Panel, packaged in a Dictionary using StringName constants as keys. */
 		godot::Dictionary get_province_info_from_index(int32_t index) const;