Credits Crash Bug fix (#7931)

Co-authored-by: pentarctagon <pentarctagon@tutamail.com>

src/gui/dialogs/end_credits.cpp

@@ -44,13 +44,14 @@ end_credits::end_credits(const std::string& campaign)
 	, text_widget_(nullptr)
 	, scroll_speed_(100)
 	, last_scroll_(std::numeric_limits<uint32_t>::max())
+	, first_idx_(0)
+	, last_idx_(first_idx_ + sliding_size_)
 {
 }
 
 void end_credits::pre_show(window& window)
 {
-	// Delay a little before beginning the scrolling
-	last_scroll_ = SDL_GetTicks() + 3000;
+	last_scroll_ = SDL_GetTicks();
 
 	connect_signal_pre_key_press(window, std::bind(&end_credits::key_press_callback, this, std::placeholders::_5));
 
@@ -93,8 +94,31 @@ void end_credits::pre_show(window& window)
 
 	text_widget_->set_use_markup(true);
 	text_widget_->set_link_aware(false);
-	text_widget_->set_label((focus_ss.str().empty() ? ss : focus_ss).str());
 
+	content_ = focus_ss.str().empty() ? ss.str() : focus_ss.str();
+
+	// splits the content text by newline, leaving blanks
+	// also truncates the length of the line to 200 characters
+	// 200 characters is completely arbitrary, just prevent the possibility of ridiculously wide lines
+	// NOTE: this depends on the assumption that the <span>s added above only ever wrap a single line
+	std::vector<std::string> lines = utils::split(content_, '\n', 0);
+	int i = 0;
+	for(const std::string& line : lines) {
+		if(i % lines_per_chunk_ == 0) {
+			chunks_.emplace_back();
+		}
+		std::vector<std::string>& last_chunk = chunks_[chunks_.size()-1];
+		last_chunk.emplace_back(line.size() < 200 ? line : line.substr(0, 200));
+		i++;
+	}
+
+	sliding_content_.clear();
+	for(std::size_t i = 0; i <= sliding_size_; i++){
+		sliding_content_ += utils::join(chunks_.at(i), "\n") + "\n";
+	}
+
+	//concat substring strings
+	text_widget_->set_label(sliding_content_);
 	// HACK: always hide the scrollbar, even if it's needed.
 	// This should probably be implemented as a scrollbar mode.
 	// Also, for some reason hiding the whole grid doesn't work, and the elements need to be hidden manually
@@ -122,7 +146,27 @@ void end_credits::update()
 	// The division by 1000 is to convert milliseconds to seconds.
 	unsigned int needed_dist = missed_time * scroll_speed_ / 1000;
 
-	text_widget_->set_vertical_scrollbar_item_position(cur_pos + needed_dist);
+	// TODO: this doesn't allow for scrolling up again after been scrolled down
+	// only the content in the current sliding window can be scrolled up
+	if(cur_pos <= text_widget_->get_height()){
+		text_widget_->set_vertical_scrollbar_item_position(cur_pos + needed_dist);
+	} else {
+		if(first_idx_ < chunks_.size() - sliding_size_ - 1){
+			first_idx_++;
+			last_idx_ = first_idx_ + sliding_size_;
+			sliding_content_.clear();
+
+			if(last_idx_ <= chunks_.size()){
+				for(std::size_t i = first_idx_; i <= last_idx_; i++) {
+					sliding_content_ += utils::join(chunks_[i], "\n") + "\n";
+				}
+			}
+
+			// updates the sliding window
+			text_widget_->set_label(sliding_content_);
+			cur_pos = 0;
+		}
+	}
 
 	last_scroll_ = now;
 }

src/gui/dialogs/end_credits.hpp

@@ -44,7 +44,6 @@ private:
 
 	virtual void pre_show(window& window) override;
 
-	void timer_callback();
 	void key_press_callback(const SDL_Keycode key);
 
 	const std::string& focus_on_;
@@ -57,6 +56,22 @@ private:
 	int scroll_speed_;
 
 	uint32_t last_scroll_;
+
+	/**
+	 * sliding_size_ alters how many of the sliding contents are to be run at once
+	 * n-1 = 2 => 3 strings at once concatinated
+	 */
+	static constexpr std::size_t sliding_size_ = 2;
+	/**
+	 * number of lines to put in each chunk of text to display
+	 * the final chunk will of course probably have fewer lines
+	 */
+	static constexpr std::size_t lines_per_chunk_ = 50;
+	std::size_t first_idx_;
+	std::size_t last_idx_;
+	std::string content_;
+	std::string sliding_content_;
+	std::vector<std::vector<std::string>> chunks_;
 };
 
 } // namespace dialogs