Prepare wibox.widget.base for new widget system

Signed-off-by: Uli Schlachter <psychon@znc.in>

lib/wibox/layout/base.lua

@@ -26,7 +26,7 @@ function base.fit_widget(context, widget, width, height)
     local width = math.max(0, width)
     local height = math.max(0, height)
 
-    local w, h = widget._fit_geometry_cache:get(context, width, height)
+    local w, h = widget:fit(context, width, height)
 
     -- Also sanitize the output.
     w = math.max(0, math.min(w, width))

lib/wibox/widget/base.lua

@@ -7,8 +7,8 @@
 
 local debug = require("gears.debug")
 local object = require("gears.object")
-local cache = require("gears.cache")
 local matrix = require("gears.matrix")
+local Matrix = require("lgi").cairo.Matrix
 local setmetatable = setmetatable
 local pairs = pairs
 local type = type
@@ -22,7 +22,67 @@ function base.rect_to_device_geometry(cr, x, y, width, height)
     return matrix.transform_rectangle(cr.matrix, x, y, width, height)
 end
 
---- Set/get a widget's buttons
+--- Fit a widget for the given available width and height. This calls the
+-- widget's `:fit` callback and caches the result for later use. Never call
+-- `:fit` directly, but always through this function!
+-- @param context The context in which we are fit.
+-- @param widget The widget to fit (this uses widget:fit(width, height)).
+-- @param width The available width for the widget
+-- @param height The available height for the widget
+-- @return The width and height that the widget wants to use
+function base.fit_widget(context, widget, width, height)
+    if not widget.visible then
+        return 0, 0
+    end
+
+    -- Sanitize the input. This also filters out e.g. NaN.
+    local width = math.max(0, width)
+    local height = math.max(0, height)
+
+    local w, h = 0, 0
+    if widget.fit then
+        w, h = widget:fit(context, width, height)
+    else
+        -- If it has no fit method, calculate based on the size of children
+        local children = base.layout_widget(context, widget, width, height)
+        for _, info in ipairs(children or {}) do
+            local x, y, w2, h2 = matrix.transform_rectangle(info._matrix,
+                0, 0, info._width, info._height)
+            w, h = math.max(w, x + w2), math.max(h, y + h2)
+        end
+    end
+
+    -- Also sanitize the output.
+    w = math.max(0, math.min(w, width))
+    h = math.max(0, math.min(h, height))
+    return w, h
+end
+
+--- Lay out a widget for the given available width and height. This calls the
+-- widget's `:layout` callback and caches the result for later use. Never call
+-- `:layout` directly, but always through this function! However, normally there
+-- shouldn't be any reason why you need to use this function.
+-- @param context The context in which we are laid out.
+-- @param widget The widget to layout (this uses widget:layout(context, width, height)).
+-- @param width The available width for the widget
+-- @param height The available height for the widget
+-- @return The result from the widget's `:layout` callback.
+function base.layout_widget(context, widget, width, height)
+    if not widget.visible then
+        return
+    end
+
+    -- Sanitize the input. This also filters out e.g. NaN.
+    local width = math.max(0, width)
+    local height = math.max(0, height)
+
+    if widget.layout then
+        return widget:layout(context, width, height)
+    end
+end
+
+--- Set/get a widget's buttons.
+-- This function is available on widgets created by @{make_widget}.
 function base:buttons(_buttons)
     if _buttons then
         self.widget_buttons = _buttons
@@ -68,6 +128,40 @@ function base.handle_button(event, widget, x, y, button, modifiers, geometry)
     end
 end
 
+--- Create widget placement information. This should be used for a widget's
+-- :layout() callback.
+-- @param widget The widget that should be placed.
+-- @param mat A cairo matrix transforming from the parent widget's coordinate
+--        system. For example, use cairo.Matrix.create_translate(1, 2) to draw a
+--        widget at position (1, 2) relative to the parent widget.
+-- @param width The width of the widget in its own coordinate system. That is,
+--        after applying the transformation matrix.
+-- @param height The height of the widget in its own coordinate system. That is,
+--        after applying the transformation matrix.
+-- @return An opaque object that can be returned from :layout()
+function base.place_widget_via_matrix(widget, mat, width, height)
+    return {
+        _widget = widget,
+        _width = width,
+        _height = height,
+        _matrix = matrix.copy(mat)
+    }
+end
+
+--- Create widget placement information. This should be used for a widget's
+-- :layout() callback.
+-- @param widget The widget that should be placed.
+-- @param x The x coordinate for the widget.
+-- @param y The y coordinate for the widget.
+-- @param width The width of the widget in its own coordinate system. That is,
+--        after applying the transformation matrix.
+-- @param height The height of the widget in its own coordinate system. That is,
+--        after applying the transformation matrix.
+-- @return An opaque object that can be returned from :layout()
+function base.place_widget_at(widget, x, y, width, height)
+    return base.place_widget_via_matrix(widget, Matrix.create_translate(x, y), width, height)
+end
+
 --- Create a new widget. All widgets have to be generated via this function so
 -- that the needed signals are added and mouse input handling is set up.
 -- @param proxy If this is set, the returned widget will be a proxy for this
@@ -78,13 +172,22 @@ function base.make_widget(proxy, widget_name)
     local ret = object()
 
     -- This signal is used by layouts to find out when they have to update.
-    ret:add_signal("widget::updated")
+    ret:add_signal("widget::layout_changed")
+    ret:add_signal("widget::redraw_needed")
     -- Mouse input, oh noes!
     ret:add_signal("button::press")
     ret:add_signal("button::release")
     ret:add_signal("mouse::enter")
     ret:add_signal("mouse::leave")
 
+    -- Backwards compatibility
+    -- TODO: Remove this
+    ret:add_signal("widget::updated")
+    ret:connect_signal("widget::updated", function()
+        ret:emit_signal("widget::layout_changed")
+        ret:emit_signal("widget::redraw_needed")
+    end)
+
     -- No buttons yet
     ret.widget_buttons = {}
     ret.buttons = base.buttons
@@ -98,28 +201,28 @@ function base.make_widget(proxy, widget_name)
     end)
 
     if proxy then
-        ret.draw = function(_, ...) return proxy:draw(...) end
+        ret.fit = function(_, context, width, height)
-        ret.fit = function(_, ...) return proxy:fit(...) end
+            return base.fit_widget(context, proxy, width, height)
-        proxy:connect_signal("widget::updated", function()
+        end
-            ret:emit_signal("widget::updated")
+        ret.layout = function(_, context, width, height)
+            return { base.place_widget_at(proxy, 0, 0, width, height) }
+        end
+        proxy:connect_signal("widget::layout_changed", function()
+            ret:emit_signal("widget::layout_changed")
+        end)
+        proxy:connect_signal("widget::redraw_needed", function()
+            ret:emit_signal("widget::redraw_needed")
         end)
     end
 
-    -- Add a geometry for base.fit_widget() that is cleared when necessary
-    local function cb(...)
-        return ret:fit(...)
-    end
-    ret._fit_geometry_cache = cache.new(cb)
-    ret:connect_signal("widget::updated", function()
-        ret._fit_geometry_cache = cache.new(cb)
-    end)
-
     -- Add visible property and setter.
     ret.visible = true
     function ret:set_visible(b)
         if b ~= self.visible then
             self.visible = b
-            self:emit_signal("widget::updated")
+            self:emit_signal("widget::layout_changed")
+            -- In case something ignored fit and drew the widget anyway
+            self:emit_signal("widget::redraw_needed")
         end
     end
 
@@ -128,7 +231,7 @@ function base.make_widget(proxy, widget_name)
     function ret:set_opacity(b)
         if b ~= self.opacity then
             self.opacity = b
-            self:emit_signal("widget::updated")
+            self:emit_signal("widget::redraw")
         end
     end
 
@@ -144,23 +247,16 @@ end
 
 --- Generate an empty widget which takes no space and displays nothing
 function base.empty_widget()
-    local widget = base.make_widget()
+    return base.make_widget()
-    widget.draw = function() end
-    widget.fit = function() return 0, 0 end
-    return widget
 end
 
 --- Do some sanity checking on widget. This function raises a lua error if
 -- widget is not a valid widget.
 function base.check_widget(widget)
     debug.assert(type(widget) == "table")
-    for k, func in pairs({ "draw", "fit", "add_signal", "connect_signal", "disconnect_signal" }) do
+    for k, func in pairs({ "add_signal", "connect_signal", "disconnect_signal" }) do
         debug.assert(type(widget[func]) == "function", func .. " is not a function")
     end
-
-    local width, height = widget:fit({}, 0, 0)
-    debug.assert(type(width) == "number")
-    debug.assert(type(height) == "number")
 end
 
 return base