osc.lua: fix element touch handling

On some compositors, when all touch points disappear the compositors
reset the mouse position, which moves the mouse out of the osc element
trigger area so mouse up events do not happen.

Fix this by tracking the last touch position and use that as the virt
mouse position if the screen is recently touched.

Author: na-na-hi

player/lua/osc.lua

@@ -227,6 +227,7 @@ end
 local state = {
     showtime = nil,                         -- time of last invocation (last mouse move)
     touchtime = nil,                        -- time of last invocation (last touch event)
+    touchpoints = {},                       -- current touch points
     osc_visible = false,
     anistart = nil,                         -- time when the animation started
     anitype = nil,                          -- current type of animation
@@ -240,6 +241,7 @@ local state = {
     initREQ = false,                        -- is a re-init request pending?
     marginsREQ = false,                     -- is a margins update pending?
     last_mouseX = nil, last_mouseY = nil,   -- last mouse position, to detect significant mouse movement
+    last_touchX = -1, last_touchY = -1,     -- last touch position
     mouse_in_window = false,
     fullscreen = false,
     tick_timer = nil,
@@ -333,9 +335,19 @@ local function get_virt_scale_factor()
     return osc_param.playresx / w, osc_param.playresy / h
 end
 
+local function recently_touched()
+    if state.touchtime == nil then
+        return false
+    end
+    return state.touchtime + 1 >= mp.get_time()
+end
+
 -- return mouse position in virtual ASS coordinates (playresx/y)
 local function get_virt_mouse_pos()
-    if state.mouse_in_window then
+    if recently_touched() then
+        local sx, sy = get_virt_scale_factor()
+        return state.last_touchX * sx, state.last_touchY * sy
+    elseif state.mouse_in_window then
         local sx, sy = get_virt_scale_factor()
         local x, y = mp.get_mouse_pos()
         return x * sx, y * sy
@@ -2242,9 +2254,17 @@ local function mouse_leave()
     state.mouse_in_window = false
 end
 
-local function handle_touch()
-    --remember last time of invocation (touch event)
-    state.touchtime = mp.get_time()
+local function handle_touch(_, touchpoints)
+    --remember last touch points
+    if touchpoints then
+        state.touchpoints = touchpoints
+        if #touchpoints > 0 then
+            --remember last time of invocation (touch event)
+            state.touchtime = mp.get_time()
+            state.last_touchX = touchpoints[1].x
+            state.last_touchY = touchpoints[1].y
+        end
+    end
 end