From cfc9e41222111ba0d87f0777b10091befda3e84a Mon Sep 17 00:00:00 2001
From: dec05eba <dec05eba@protonmail.com>
Date: Thu, 16 Jul 2020 15:11:28 +0200
Subject: Add middle-mouse-scroll (aka autoscroll) for infinite image view mode

---
 src/ImageViewer.cpp | 39 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 34 insertions(+), 5 deletions(-)

(limited to 'src/ImageViewer.cpp')

diff --git a/src/ImageViewer.cpp b/src/ImageViewer.cpp
index 574bf94..9777611 100644
--- a/src/ImageViewer.cpp
+++ b/src/ImageViewer.cpp
@@ -28,6 +28,9 @@ namespace QuickMedia {
             page_size[i].loaded = false;
         }
         page_text.setFillColor(sf::Color::White);
+
+        has_default_cursor = default_cursor.loadFromSystem(sf::Cursor::Arrow);
+        has_size_vertical_cursor = size_vertical_cursor.loadFromSystem(sf::Cursor::SizeVertical);
     }
 
     bool ImageViewer::render_page(sf::RenderWindow &window, int page, double offset_y) {
@@ -118,6 +121,7 @@ namespace QuickMedia {
         const double frame_delta = frame_timer.restart().asSeconds();
         const double scroll_speed_key_input = 450.0;
         const double scroll_speed_mouse_wheel = 600.0;
+        const double scroll_speed_autoscroll = 10.0;
         const double scroll_deaccel = 0.96;
 
         if(!window_size_set) {
@@ -131,7 +135,8 @@ namespace QuickMedia {
         sf::Event event;
         while(window.pollEvent(event)) {
             if (event.type == sf::Event::Closed) {
-                //current_page = Page::EXIT;
+                if(has_default_cursor)
+                    window.setMouseCursor(default_cursor);
                 window.close();
                 return ImageViewerAction::RETURN;
             } else if(event.type == sf::Event::Resized) {
@@ -148,19 +153,43 @@ namespace QuickMedia {
                 } else if(event.key.code == sf::Keyboard::Down) {
                     scroll_speed -= scroll_speed_key_input * frame_delta;
                 } else if(event.key.code == sf::Keyboard::Escape) {
+                    if(has_default_cursor)
+                        window.setMouseCursor(default_cursor);
                     return ImageViewerAction::RETURN;
                 } else if(event.key.code == sf::Keyboard::I) {
                     return ImageViewerAction::SWITCH_TO_SINGLE_IMAGE_MODE;
                 }
             } else if(event.type == sf::Event::MouseWheelScrolled && event.mouseWheelScroll.wheel == sf::Mouse::VerticalWheel) {
                 scroll_speed += scroll_speed_mouse_wheel * event.mouseWheelScroll.delta * frame_delta;
+            } else if(event.type == sf::Event::MouseButtonPressed && event.mouseButton.button == sf::Mouse::Button::Middle) {
+                middle_mouse_scrolling = true;
+                autoscroll_start_y = sf::Mouse::getPosition(window).y;
+                if(has_size_vertical_cursor)
+                    window.setMouseCursor(size_vertical_cursor);
+
+            } else if(event.type == sf::Event::MouseButtonReleased && event.mouseButton.button == sf::Mouse::Button::Middle) {
+                middle_mouse_scrolling = false;
+                scroll_speed = 0.0;
+                if(has_default_cursor)
+                    window.setMouseCursor(default_cursor);
             }
         }
 
-        scroll += scroll_speed;
-        scroll *= scroll_deaccel;
-        if(std::abs(scroll) < 0.1)
-            scroll = 0.0;
+        if(middle_mouse_scrolling) {
+            double distance_to_start_y = (double)sf::Mouse::getPosition(window).y - autoscroll_start_y;
+            scroll_speed = -distance_to_start_y * scroll_speed_autoscroll * frame_delta;
+            const double max_speed = 100.0;
+            if(scroll_speed > max_speed)
+                scroll_speed = max_speed;
+            if(scroll_speed < -max_speed)
+                scroll_speed = -max_speed;
+            scroll += scroll_speed;
+        } else {
+            scroll_speed *= scroll_deaccel;
+            if(std::abs(scroll_speed) < 0.01)
+                scroll_speed = 0.0;
+            scroll += scroll_speed;
+        }
 
         min_page_center_dist = 9999999.0;
         page_closest_to_center = -1;
-- 
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