Add View dragging (#1402)

data/core/init.lua

@@ -1289,6 +1289,12 @@ function core.on_event(type, ...)
     if not core.root_view:on_mouse_wheel(...) then
       did_keymap = keymap.on_mouse_wheel(...)
     end
+  elseif type == "touchpressed" then
+    core.root_view:on_touch_pressed(...)
+  elseif type == "touchreleased" then
+    core.root_view:on_touch_released(...)
+  elseif type == "touchmoved" then
+    core.root_view:on_touch_moved(...)
   elseif type == "resized" then
     core.window_mode = system.get_window_mode()
   elseif type == "minimized" or type == "maximized" or type == "restored" then

data/core/node.lua

@@ -60,6 +60,13 @@ function Node:on_mouse_left()
   end
 end
 
+function Node:on_touch_moved(...)
+  if self.type == "leaf" then
+    self.active_view:on_touch_moved(...)
+  else
+    self:propagate("on_touch_moved", ...)
+  end
+end
 
 function Node:consume(node)
   for k, _ in pairs(self) do self[k] = nil end

data/core/rootview.lua

@@ -334,6 +334,49 @@ function RootView:on_text_input(...)
   core.active_view:on_text_input(...)
 end
 
+function RootView:on_touch_pressed(x, y, ...)
+  self.touched_node = self.root_node:get_child_overlapping_point(x, y)
+end
+
+function RootView:on_touch_released(x, y, ...)
+  self.touched_node = nil
+end
+
+function RootView:on_touch_moved(x, y, dx, dy, ...)
+  if not self.touched_node then return end
+  if core.active_view == core.nag_view then
+    core.active_view:on_touch_moved(x, y, dx, dy, ...)
+    return
+  end
+
+  if self.dragged_divider then
+    local node = self.dragged_divider
+    if node.type == "hsplit" then
+      x = common.clamp(x, 0, self.root_node.size.x * 0.95)
+      resize_child_node(node, "x", x, dx)
+    elseif node.type == "vsplit" then
+      y = common.clamp(y, 0, self.root_node.size.y * 0.95)
+      resize_child_node(node, "y", y, dy)
+    end
+    node.divider = common.clamp(node.divider, 0.01, 0.99)
+    return
+  end
+
+  local dn = self.dragged_node
+  if dn and not dn.dragging then
+    -- start dragging only after enough movement
+    dn.dragging = common.distance(x, y, dn.drag_start_x, dn.drag_start_y) > style.tab_width * .05
+    if dn.dragging then
+      core.request_cursor("hand")
+    end
+  end
+
+  -- avoid sending on_touch_moved events when dragging tabs
+  if dn then return end
+
+  self.touched_node:on_touch_moved(x, y, dx, dy, ...)
+end
+
 function RootView:on_ime_text_editing(...)
   core.active_view:on_ime_text_editing(...)
 end

data/core/view.lua

@@ -248,6 +248,23 @@ function View:get_content_bounds()
   return x, y, x + self.size.x, y + self.size.y
 end
 
+---@param x number
+---@param y number
+---@param dx number
+---@param dy number
+---@param i number
+function View:on_touch_moved(x, y, dx, dy, i)
+  if not self.scrollable then return end
+  if self.dragging_scrollbar then
+    local delta = self:get_scrollable_size() / self.size.y * dy
+    self.scroll.to.y = self.scroll.to.y + delta
+  end
+  self.hovered_scrollbar = self:scrollbar_overlaps_point(x, y)
+
+  self.scroll.to.y = self.scroll.to.y + -dy
+  self.scroll.to.x = self.scroll.to.x + -dx
+end
+
 
 ---@return number x
 ---@return number y