Slider dragging signals

lib/wibox/widget/slider.lua

@@ -274,6 +274,28 @@
 -- @beautiful beautiful.slider_bar_active_color
 -- @param color
 
+--- Emitted when the user starts dragging the handle.
+--
+-- @signal drag_start
+-- @tparam number value The current value
+
+--- Emitted for every mouse move while the handle is being dragged.
+--
+-- This signal is only emitted by the user dragging the handle. It is therefore
+-- preferrable over `property::value`, as it cannot create a loop when trying to
+-- hook up the slider as representation of an external value (e.g. system
+-- volume).
+--
+-- @signal drag
+-- @tparam number value The current value
+
+--- Emitted when the user stops dragging the handle.
+--
+-- This signal is emitted when the user releases the mouse button after dragging
+-- the handle.
+--
+-- @signal drag_end
+-- @tparam number value The current value
 
 local properties = {
     -- Handle
@@ -334,6 +356,15 @@
     end
 end
 
+--- Returns `true` while the user is dragging the handle.
+--
+-- @property is_dragging
+-- @propertydefault Depends on the current dragging state.
+-- @treturn boolean
+function slider:get_is_dragging()
+    return self._private.is_dragging
+end
+
 local function get_extremums(self)
     local min = self._private.minimum or properties.minimum
     local max = self._private.maximum or properties.maximum
@@ -535,6 +566,9 @@
 
     move_handle(self, width, x, y)
 
+    self._private.is_dragging = true
+    self:emit_signal("drag_start", self.value)
+
     -- Calculate a matrix transforming from screen coordinates into widget coordinates
     local wgeo = geo.drawable.drawable:geometry()
     local matrix = matrix_from_device:translate(-wgeo.x, -wgeo.y)
@@ -545,11 +579,14 @@
 
     capi.mousegrabber.run(function(mouse)
         if not mouse.buttons[1] then
+            self._private.is_dragging = false
+            self:emit_signal("drag_end", self.value)
             return false
         end
 
         -- Calculate the point relative to the widget
         move_handle(self, width, matrix:transform_point(mouse.x, mouse.y))
+        self:emit_signal("drag", self.value)
 
         return true
     end,handle_cursor)

tests/test-wibox-widget-slider.lua

@@ -0,0 +1,111 @@
+local runner = require("_runner")
+local wibox = require("wibox")
+local gears = {
+    shape = require("gears.shape")
+}
+
+local steps = {}
+
+-- The test runner doesn't support it (yet), but it would be nice to have named
+-- steps.
+local function step(_, func)
+    table.insert(steps, func)
+end
+
+-- Apparently in CI the wibox won't always be at the coordinates we specify.
+-- So we'll have to click around blindly until we find our widget,
+-- then use those coordinates as offset for the actual test.
+local offset_x = nil
+local offset_y = nil
+
+local w
+local slider
+
+local on_mouse_press = nil
+local on_drag_start = nil
+local on_drag = nil
+local on_drag_end = nil
+local on_property_value = nil
+
+step("create slider widget", function()
+    slider = wibox.widget.slider {
+        minimum = 0,
+        maximum = 100,
+        bar_shape = gears.shape.rounded_rect,
+        bar_height = 3,
+        bar_color = "#ffffff",
+        handle_color = "#0000ff",
+        handle_shape = gears.shape.circle,
+        handle_border_color = "#ffffff",
+        handle_border_width = 1,
+    }
+
+    slider:connect_signal("button::press", function()
+        on_mouse_press = true
+
+        if offset_x ~= nil then
+            return
+        end
+
+        local coords = mouse.coords()
+        offset_x = coords.x
+        offset_y = coords.y
+        print(coords.x, coords.y)
+    end)
+    slider:connect_signal("drag_start", function() on_drag_start = true end)
+    slider:connect_signal("drag", function() on_drag = true end)
+    slider:connect_signal("drag_end", function() on_drag_end = true end)
+    slider:connect_signal("property::value", function() on_property_value = true end)
+
+    w = wibox {
+        ontop = true,
+        x = 0,
+        y = 0,
+        width = 250,
+        height = 50,
+        visible = true,
+        widget = slider,
+    }
+
+    -- Mute luacheck warning
+    assert(w.ontop)
+
+    return true
+end)
+
+for x = 0, 2000, 5 do
+    for y = 0, 2000, 5 do
+        step("find widget", function()
+            if offset_x ~= nil then
+                return true
+            end
+
+            mouse.coords({ x = x, y = y })
+            root.fake_input("button_press", 1)
+            root.fake_input("button_release", 1)
+
+            return true
+        end)
+    end
+end
+
+step("test dragging", function()
+    mouse.coords({ x = offset_x, y = offset_y })
+    root.fake_input("button_press", 1)
+    mouse.coords({ x = offset_x + 100, offset_y })
+    root.fake_input("button_release", 1)
+    return true
+end)
+
+step("check signals", function()
+    assert(on_mouse_press, "Signal `button::press` was not called")
+    assert(on_drag_start, "Signal `drag_start` was not called")
+    assert(on_property_value, "Signal `property::value` was not called")
+    assert(on_drag, "Signal `drag` was not called")
+    assert(on_drag_end, "Signal `drag_end` was not called")
+    return true
+end)
+
+runner.run_steps(steps)
+
+-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80