From 0a39d196c7144e386c4924598b8f8f0418c8070a Mon Sep 17 00:00:00 2001
From: Emmanuel Lepage Vallee <elv1313@gmail.com>
Date: Sun, 10 Jan 2016 02:39:14 -0500
Subject: [PATCH] wibox.layout: Add the new 'ratio' layout

This layout allow each widgets to take 'r' percent of the total
space, where 'r' is configurable.

It re-implement the 'wfact' system used by `awful.layout.suit.tile`
---
 lib/wibox/layout/init.lua  |   1 +
 lib/wibox/layout/ratio.lua | 364 +++++++++++++++++++++++++++++++++++++
 2 files changed, 365 insertions(+)
 create mode 100644 lib/wibox/layout/ratio.lua

diff --git a/lib/wibox/layout/init.lua b/lib/wibox/layout/init.lua
index 66fbafec..386d9f19 100644
--- a/lib/wibox/layout/init.lua
+++ b/lib/wibox/layout/init.lua
@@ -17,6 +17,7 @@ return
     mirror = require("wibox.layout.mirror");
     constraint = require("wibox.layout.constraint");
     scroll = require("wibox.layout.scroll");
+    ratio = require("wibox.layout.ratio");
     stack = require("wibox.layout.stack");
 }
 
diff --git a/lib/wibox/layout/ratio.lua b/lib/wibox/layout/ratio.lua
new file mode 100644
index 00000000..201e1de6
--- /dev/null
+++ b/lib/wibox/layout/ratio.lua
@@ -0,0 +1,364 @@
+---------------------------------------------------------------------------
+--- A layout filling all the available space. Each widget is assigned a
+-- ratio (percentage) of the total space. Multiple methods are available to
+-- ajust this ratio.
+-- @author Emmanuel Lepage Vallee
+-- @copyright 2016 Emmanuel Lepage Vallee
+-- @release @AWESOME_VERSION@
+-- @classmod wibox.layout.ratio
+---------------------------------------------------------------------------
+
+local base  = require("wibox.widget.base" )
+local flex  = require("wibox.layout.flex" )
+local fixed = require("wibox.layout.fixed")
+local table = table
+local pairs = pairs
+local floor = math.floor
+local util  = require("awful.util")
+
+local ratio = {}
+
+--- Set a widget at a specific index, replace the current one
+-- @tparam number index A widget or a widget index
+-- @param widget2 The widget to take the place of the first one
+-- @treturn boolean If the operation is successful
+-- @name set
+-- @class function
+
+--- Replace the first instance of `widget` in the layout with `widget2`
+-- @param widget The widget to replace
+-- @param widget2 The widget to replace `widget` with
+-- @tparam[opt=false] boolean recursive Digg in all compatible layouts to find the widget.
+-- @treturn boolean If the operation is successful
+-- @name replace_widget
+-- @class function
+
+--- Swap 2 widgets in a layout
+-- @tparam number index1 The first widget index
+-- @tparam number index2 The second widget index
+-- @treturn boolean If the operation is successful
+-- @name swap
+-- @class function
+
+--- Swap 2 widgets in a layout
+-- If widget1 is present multiple time, only the first instance is swapped
+-- @param widget1 The first widget
+-- @param widget2 The second widget
+-- @tparam[opt=false] boolean recursive Digg in all compatible layouts to find the widget.
+-- @treturn boolean If the operation is successful
+-- @name swap_widgets
+-- @class function
+
+--- Get all children of this layout.
+-- @param layout The layout you are modifying.
+-- @return a list of all widgets
+-- @name get_children
+-- @class function
+
+--- Fit the ratio layout into the given space
+-- @param layout The layout you are modifying.
+-- @param context The context in which we are fit.
+-- @tparam number orig_width The available width.
+-- @tparam number orig_height The available height.
+-- @name fit
+-- @class function
+
+--- Reset a ratio layout. This removes all widgets from the layout.
+-- @param layout The layout you are modifying.
+-- @name reset
+-- @class function
+
+-- Compute the sum of all ratio (ideally, it should be 1)
+local function gen_sum(self, i_s, i_e)
+    local sum, new_w = 0,0
+
+    for i = i_s or 1, i_e or #self.widgets do
+        if self._ratios[i] then
+            sum = sum + self._ratios[i]
+        else
+            new_w = new_w + 1
+        end
+    end
+
+    return sum, new_w
+end
+
+-- The ratios are expressed as percentages. For this to work, the sum of all
+-- ratio must be 1. This function attempt to ajust them. Space can be taken
+-- from or added to a ratio when widgets are being added or removed. If a
+-- specific ratio must be enforced for a widget, it has to be done with the
+-- `ajust_ratio` method after each insertion or deletion
+local function normalize(self)
+    local count = #self.widgets
+    if count == 0 then return end
+
+    -- Instead of adding "if" everywhere, just handle this common case
+    if count == 1 then
+        self._ratios = { 1 }
+        return
+    end
+
+    local sum, new_w = gen_sum(self)
+    local old_count  = #self.widgets - new_w
+
+    local to_add = (sum == 0) and 1 or (sum / old_count)
+
+    -- Make sure all widgets have a ratio
+    for i=1, #self.widgets do
+        if not self._ratios[i] then
+            self._ratios[i] = to_add
+        end
+    end
+
+    sum = sum + to_add*new_w
+
+    local delta, new_sum =  (1 - sum) / count,0
+
+    -- Increase or decrease each ratio so it the sum become 1
+    for i=1, #self.widgets do
+        self._ratios[i] = self._ratios[i] + delta
+        new_sum = new_sum + self._ratios[i]
+    end
+
+    -- Floating points is not an exact science, but it should still be close
+    -- to 1.00.
+    assert(new_sum > 0.99 and new_sum < 1.01)
+end
+
+--- Layout a ratio layout. Each widget gets a share of the size proportional
+-- to its ratio
+-- @param context The context in which we are drawn.
+-- @tparam number width The available width.
+-- @tparam number height The available height.
+function ratio:layout(context, width, height)
+    local result = {}
+    local pos,spacing = 0, self._spacing
+    local num = #self.widgets
+    local total_spacing = (spacing*(num-1))
+
+    --normalize(self)
+
+    for k, v in ipairs(self.widgets) do
+        local space = nil
+        local x, y, w, h
+
+        if self.dir == "y" then
+            space = height * self._ratios[k]
+            x, y = 0, util.round(pos)
+            w, h = width, floor(space)
+        else
+            space = width * self._ratios[k]
+            x, y = util.round(pos), 0
+            w, h = floor(space), height
+        end
+
+        table.insert(result, base.place_widget_at(v, x, y, w, h))
+
+        pos = pos + space + spacing
+
+        -- Make sure all widgets fit in the layout, if they aren't, something
+        -- went wrong
+        if (self.dir == "y" and util.round(pos) >= height) or
+            (self.dir ~= "y" and util.round(pos) >= width) then
+            break
+        end
+    end
+
+    return result
+end
+
+--- Increase the ratio of "widget"
+-- If the increment produce an invalid ratio (not between 0 and 1), the method
+-- do nothing.
+-- @tparam number index The widget index to change
+-- @tparam number increment An floating point value between -1 and 1 where the
+--   end result is within 0 and 1
+function ratio:inc_ratio(index, increment)
+    if #self.widgets ==  1 or (not index) or (not self._ratios[index])
+      or increment < -1 or increment > 1 then
+        return
+    end
+
+    local widget = self.widgets[index]
+
+    assert(self._ratios[index])
+
+    self:set_ratio(index, self._ratios[index] + increment)
+end
+
+--- Increment the ratio of the first instance of `widget`
+-- If the increment produce an invalid ratio (not between 0 and 1), the method
+-- do nothing.
+-- @param widget The widget to ajust
+-- @tparam number increment An floating point value between -1 and 1 where the
+--   end result is within 0 and 1
+function ratio:inc_widget_ratio(widget, increment)
+    if not widget or not increment then return end
+
+    local index = self:index(widget)
+
+    self:inc_ratio(index, increment)
+end
+
+--- Set the ratio of the widget at position `index`
+-- @tparam number index The index of the widget to change
+-- @tparam number percent An floating point value between 0 and 1
+function ratio:set_ratio(index, percent)
+    if not percent or #self.widgets ==  1 or not index or not self.widgets[index]
+        or percent < 0 or percent > 1 then
+        return
+    end
+
+    local old = self._ratios[index]
+
+    -- Remove what has to be cleared from all widget
+    local delta = ( (percent-old) / (#self.widgets-1) )
+
+    for k, v in pairs(self.widgets) do
+        self._ratios[k] = self._ratios[k] - delta
+    end
+
+    -- Set the new ratio
+    self._ratios[index] = percent
+
+    -- As some widgets may now have a slightly negative ratio, normalize again
+    normalize(self)
+
+    self:emit_signal("widget::layout_changed")
+end
+
+--- Set the ratio of "widget"
+-- @param widget The widget to ajust
+-- @tparam number percent An floating point value between 0 and 1
+function ratio:set_widget_ratio(widget, percent)
+    local index = self:index(widget)
+
+    self:set_ratio(index, percent)
+end
+
+--- Update all widgets to match a set of a ratio.
+-- The sum of before, itself and after must be 1 or nothing will be done
+-- @tparam number index The index of the widget to change
+-- @tparam number before The sum of the ratio before the widget
+-- @tparam number itself The ratio for "widget"
+-- @tparam number after The sum of the ratio after the widget
+function ratio:ajust_ratio(index, before, itself, after)
+    if not self.widgets[index] or not before or not itself or not after then
+        return
+    end
+
+    local sum = before + itself + after
+
+    -- As documented, it is the caller job to come up with valid numbers
+    if math.min(before, itself, after) < 0 then return end
+    if sum > 1.01 or sum < -0.99 then return end
+
+    -- Compute the before and after offset to be applied to each widgets
+    local before_count, after_count = index-1, #self.widgets - index
+
+    local b, a = gen_sum(self, 1, index-1), gen_sum(self, index+1)
+
+    local db, da = (before - b)/before_count, (after - a)/after_count
+
+    -- Apply the new ratio
+    self._ratios[index] = itself
+
+    -- Equality split the delta among widgets before and after
+    for i = 1, index -1 do
+        self._ratios[i] = self._ratios[i] + db
+    end
+    for i = index+1, #self.widgets do
+        self._ratios[i] = self._ratios[i] + da
+    end
+
+    -- Remove potential negative ratio
+    normalize(self)
+
+    self:emit_signal("widget::layout_changed")
+end
+
+--- Update all widgets to match a set of a ratio
+-- @param widget The widget to ajust
+-- @tparam number before The sum of the ratio before the widget
+-- @tparam number itself The ratio for "widget"
+-- @tparam number after The sum of the ratio after the widget
+function ratio:ajust_widget_ratio(widget, before, itself, after)
+    local index = self:index(widget)
+    self:ajust_ratio(index, before, itself, after)
+end
+
+--- Add some widgets to the given fixed layout
+-- @tparam widget ... Widgets that should be added (must at least be one)
+function ratio:add(...)
+    -- No table.pack in Lua 5.1 :-(
+    local args = { n=select('#', ...), ... }
+    assert(args.n > 0, "need at least one widget to add")
+    for i=1, args.n do
+        base.check_widget(args[i])
+        table.insert(self.widgets, args[i])
+    end
+
+    normalize(self)
+    self:emit_signal("widget::layout_changed")
+end
+
+--- Remove a widget from the layout
+-- @tparam number index The widget index to remove
+-- @treturn boolean index If the operation is successful
+function ratio:remove(index)
+    if not index or not self.widgets[index] then return false end
+
+    table.remove(self._ratios, index)
+    table.remove(self.widgets, index)
+
+    normalize(self)
+
+    self:emit_signal("widget::layout_changed")
+
+    return true
+end
+
+--- Insert a new widget in the layout at position `index`
+-- @tparam number index The position
+-- @param widget The widget
+function ratio:insert(index, widget)
+    if not index or index < 1 or index > #self.widgets + 1 then return false end
+
+    base.check_widget(widget)
+
+    table.insert(self.widgets, index, widget)
+
+    normalize(self)
+
+    self:emit_signal("widget::layout_changed")
+end
+
+local function get_layout(dir, widget1, ...)
+    local ret = flex[dir](widget1, ...)
+
+    util.table.crush(ret, ratio)
+
+    ret.fill_space = nil
+
+    ret._ratios = {}
+
+    return ret
+end
+
+--- Returns a new horizontal ratio layout. A ratio layout shares the available space
+-- equally among all widgets. Widgets can be added via :add(widget).
+-- @tparam widget ... Widgets that should be added to the layout.
+function ratio.horizontal(...)
+    return get_layout("horizontal", ...)
+end
+
+--- Returns a new vertical ratio layout. A ratio layout shares the available space
+-- equally among all widgets. Widgets can be added via :add(widget).
+-- @tparam widget ... Widgets that should be added to the layout.
+function ratio.vertical(...)
+    return get_layout("vertical", ...)
+end
+
+return ratio
+
+-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80