GUI2/Loading Screen: improved animation

data/gui/window/loadscreen.cfg

@@ -78,13 +78,14 @@
 								[image]
 									definition = "logo"
 									label = "misc/logo-bg.png"
+									#label = "wesnoth-logo-256.png"
 								[/image]
 
 							[/column]
 
 						[/row]
 
-						{GUI_FILLER_ROW HEIGHT=30}
+						{GUI_FILLER_ROW HEIGHT=25}
 
 						[row]
 							grow_factor = 0
@@ -114,15 +115,44 @@
 								grow_factor = 1
 								border = "all"
 								border_size = 5
-								horizontal_grow = true
+								horizontal_alignment = "center"
 								vertical_alignment = "center"
 
-								[label]
-									text_alignment = "center"
-									definition = "default_large"
-									id = "test_animation"
-									label = "                    "
-								[/label]
+								[drawing]
+									definition = "default"
+									id = "animation"
+
+									width = 250
+									height = 30
+
+									#{_WIDGET_DEBUG_BORDER}
+
+									[draw]
+
+										[text]
+											#
+											# Uses a bezier in-out easing to calculate the position of the dot each frame.
+											#
+											# First, it gets a normalized [0, 1] value based on the value of `tick` in the range [0, steps], then uses
+											# this value multiplied by the width of the drawing canvas (sans the width of the text, since there still
+											# needs to be enough horizontal space to render the dot on the last step of the loop) to get this frame's
+											# x-coordinate. Note that `steps` *must* be a decimal or the formula won't work.
+											#
+											# For the record, the original linear formula I came up with was:
+											# "(floor(jump * (tick % steps)) where jump = (width / steps) where steps = 40)"
+											#
+											x = "(round(w * (t * t * (3.0 - 2.0 * t))) where w = (width - text_width) where t = ((tick % steps) / steps) where steps = 40.0)"
+											y = 0
+											w = "(text_width)"
+											h = "(height)"
+											text = "•"
+											font_size = {GUI_FONT_SIZE_DEFAULT}
+											color = {GUI__FONT_COLOR_ENABLED__DEFAULT}
+										[/text]
+
+									[/draw]
+
+								[/drawing]
 
 							[/column]
 

src/gui/dialogs/loading_screen.cpp

@@ -24,16 +24,17 @@
 #include "gettext.hpp"
 #include "gui/auxiliary/find_widget.hpp"
 #include "gui/core/timer.hpp"
+#include "gui/widgets/drawing.hpp"
 #include "gui/widgets/label.hpp"
 #include "gui/widgets/settings.hpp"
 #include "gui/widgets/window.hpp"
 #include "log.hpp"
 #include "preferences/general.hpp"
-#include <functional>
 #include "video.hpp"
 
 #include <chrono>
 #include <cstdlib>
+#include <functional>
 
 static lg::log_domain log_loadscreen("loadscreen");
 #define ERR_LS LOG_STREAM(err, log_loadscreen)
@@ -79,22 +80,13 @@ loading_screen::loading_screen(std::function<void()> f)
 	, worker_result_()
 	, cursor_setter_()
 	, progress_stage_label_(nullptr)
-	, animation_label_(nullptr)
+	, animation_(nullptr)
 	, current_stage_(loading_stage::none)
 	, visible_stages_()
-	, animation_stages_()
 	, current_visible_stage_()
 {
-	for(const auto& pair : stage_names) {
-		visible_stages_[pair.first] = t_string(pair.second, "wesnoth-lib") + "...";
-	}
-
-	animation_stages_.reserve(20);
-
-	for(int i = 0; i != 20; ++i) {
-		std::string s(20, ' ');
-		s[i] = '.';
-		animation_stages_.push_back(std::move(s));
+	for(const auto& [stage, description] : stage_names) {
+		visible_stages_[stage] = t_string(description, "wesnoth-lib") + "...";
 	}
 
 	current_visible_stage_ = visible_stages_.end();
@@ -119,7 +111,7 @@ void loading_screen::pre_show(window& window)
 	}
 
 	progress_stage_label_ = find_widget<label>(&window, "status", false, true);
-	animation_label_ = find_widget<label>(&window, "test_animation", false, true);
+	animation_ = find_widget<drawing>(&window, "animation", false, true);
 
 	// Add a draw callback to handle the animation, et al.
 	window.connect_signal<event::DRAW>(
@@ -168,10 +160,8 @@ void loading_screen::draw_callback()
 		progress_stage_label_->set_label(iter->second);
 	}
 
-	++animation_counter_;
-	if(animation_counter_ % 2 == 0) {
-		animation_label_->set_label(animation_stages_[(animation_counter_ / 2) % animation_stages_.size()]);
-	}
+	animation_->get_drawing_canvas().set_variable("tick", wfl::variant(animation_counter_++));
+	animation_->set_is_dirty(true);
 }
 
 loading_screen::~loading_screen()

src/gui/dialogs/loading_screen.hpp

@@ -63,6 +63,7 @@ enum class loading_stage
 
 namespace gui2
 {
+class drawing;
 class label;
 class window;
 
@@ -104,14 +105,12 @@ class loading_screen : public modal_dialog, public events::pump_monitor
 	std::unique_ptr<cursor::setter> cursor_setter_;
 
 	label* progress_stage_label_;
-	label* animation_label_;
+	drawing* animation_;
 
 	std::atomic<loading_stage> current_stage_;
 
 	using stage_map = std::map<loading_stage, t_string>;
 	stage_map visible_stages_;
-
-	std::vector<t_string> animation_stages_;
 	stage_map::const_iterator current_visible_stage_;
 };