From 2a364f52f194c853f2cb62122bf84039ab3e1117 Mon Sep 17 00:00:00 2001
From: dec05eba <dec05eba@protonmail.com>
Date: Sat, 29 May 2021 13:46:14 +0200
Subject: Readd body touch scroll

---
 TODO         |  1 -
 src/Body.cpp | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/TODO b/TODO
index c103c0a..1968ffd 100644
--- a/TODO
+++ b/TODO
@@ -131,6 +131,5 @@ Notification race condition when fetching the first notifications page and recei
 Submit on notifications item in matrix should jump to the message in the room.
 Notifications should load their replied-to-message.
 Readd copying of Text in Body copy constructor. Find out why we need to make the text dirty on copy.
-Readd touch scrolling to Body.
 Body items that are no longer visible should stop their thumbnail download/creation (moving to bottom of file-manager is very slow).
 Fix body flickering when moving up and there is a new local image to load. It happens because we have no idea how large the thumbnail is before loading it.
\ No newline at end of file
diff --git a/src/Body.cpp b/src/Body.cpp
index bc56ef8..24cf483 100644
--- a/src/Body.cpp
+++ b/src/Body.cpp
@@ -450,6 +450,7 @@ namespace QuickMedia {
         elapsed_time_sec = draw_timer.getElapsedTime().asSeconds();
 
         const int prev_num_visible_items = num_visible_items;
+        const bool prev_items_cut_off = top_cut_off || bottom_cut_off;
         num_visible_items = 0;
         first_visible_item = -1;
         last_visible_item = -1;
@@ -478,6 +479,58 @@ namespace QuickMedia {
             return;
         }
 
+        if(is_touch_enabled()) {
+            const sf::Vector2f mouse_pos_diff(mouse_pos_raw.x - mouse_pos.x, mouse_pos_raw.y - mouse_pos.y);
+            const float move_speed = 35.0f;
+            sf::Vector2f prev_mouse_pos = mouse_pos;
+            mouse_pos.x += (mouse_pos_diff.x * std::min(1.0f, frame_time * move_speed));
+            mouse_pos.y += (mouse_pos_diff.y * std::min(1.0f, frame_time * move_speed));
+            const sf::Vector2f mouse_pos_diff_smooth = mouse_pos - prev_mouse_pos;
+
+            sf::Vector2f mouse_pos_raw_diff(mouse_pos_raw.x - prev_mouse_pos_raw.x, mouse_pos_raw.y - prev_mouse_pos_raw.y);
+            prev_mouse_pos_raw = mouse_pos_raw;
+
+            if(prev_items_cut_off) {
+                if(mouse_left_pressed) {
+                    page_scroll += mouse_pos_diff_smooth.y;
+                    mouse_scroll_accel = sf::Vector2f(mouse_pos_raw_diff.x, mouse_pos_raw_diff.y);
+                    mouse_scroll_accel *= (float)((double)frame_time * 120.0);
+                } else {
+                    page_scroll += mouse_scroll_accel.y;
+                }
+            }
+
+            if(mouse_scroll_accel.y > 0.1f && first_visible_item != -1) {
+                selected_item = first_visible_item;
+                // TODO: Cache this
+                if(on_top_reached && get_previous_visible_item(selected_item) == -1)
+                    on_top_reached();
+            } else if(mouse_scroll_accel.y < -0.1f && last_visible_item != -1) {
+                selected_item = last_visible_item;
+                // TODO: Cache this
+                if(on_bottom_reached && get_next_visible_item(selected_item) == -1)
+                    on_bottom_reached();
+            }
+
+            if(!mouse_left_pressed) {
+                const float scroll_deaccel = 1.02f;
+                double deaccel = scroll_deaccel * (1.0 + frame_time);
+                if(deaccel > 0.0001) {
+                    mouse_scroll_accel.x /= deaccel;
+                    if(fabs(mouse_scroll_accel.x) < 0.0001)
+                        mouse_scroll_accel.x = 0.0;
+
+                    mouse_scroll_accel.y /= deaccel;
+                    if(fabs(mouse_scroll_accel.y) < 0.0001)
+                        mouse_scroll_accel.y = 0.0;
+                } else {
+                    deaccel = 0.0;
+                    mouse_scroll_accel.x = 0.0;
+                    mouse_scroll_accel.y = 0.0;
+                }
+            }
+        }
+
         const int selected_prev_item = get_previous_visible_item(selected_item);
         const bool selected_merge_with_previous = selected_prev_item != -1 && body_item_merge_handler && body_item_merge_handler(items[selected_prev_item].get(), items[selected_item].get());
         get_item_height(items[selected_item].get(), size.x, true, true, selected_merge_with_previous, selected_item);
@@ -544,6 +597,7 @@ namespace QuickMedia {
         }
 
         pos.y += selected_scrolled;
+        const float pos_y_start = pos.y;
 
         BodyItem *prev_body_item = nullptr;
         const double height_move_speed = 1000.0f;
@@ -653,6 +707,17 @@ namespace QuickMedia {
 
         window.setView(prev_view);
 
+        // TODO: Move up where scroll is limited? then we wont delay this by 1 frame creating a small scroll overflow only in the opposite direction of attach side
+        if(attach_side == AttachSide::TOP) {
+            const float body_total_height = pos.y - pos_y_start;
+            if(top_cut_off && !bottom_cut_off && body_total_height > body_size.y)
+                page_scroll = -(body_total_height - body_size.y);
+        } else {
+            const float body_total_height = pos_y_start - pos.y;
+            if(bottom_cut_off && !top_cut_off && body_total_height > body_size.y)
+                page_scroll = (body_total_height - body_size.y);
+        }
+
         const float item_target_top_diff = item_background_target_pos_y;
         const float item_target_bottom_diff = (item_background_target_pos_y + item_background_target_height + spacing_y) - body_size.y;
         if(((body_size_changed && attach_side == AttachSide::BOTTOM) || selected_item_diff < 0) && item_target_top_diff < 0.0f) {
-- 
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