awesome/lib/awful/mouse/resize.lua

---------------------------------------------------------------------------
--- An extandable mouse resizing handler.
--
-- This module offer a resizing and moving mechanism for drawable such as
-- clients and wiboxes.
--
-- @author Emmanuel Lepage Vallee <elv1313@gmail.com>
-- @copyright 2016 Emmanuel Lepage Vallee
-- @release @AWESOME_VERSION@
-- @submodule awful.mouse
---------------------------------------------------------------------------

local aplace = require("awful.placement")
local capi = {mousegrabber = mousegrabber}

local module = {}

local mode      = "live"
local req       = "request::geometry"
local callbacks = {enter={}, move={}, leave={}}

--- Set the resize mode.
-- The available modes are:
--
-- * **live**: Resize the layout everytime the mouse move
-- * **after**: Resize the layout only when the mouse is released
--
-- Some clients, such as XTerm, may lose information if resized too often.
--
-- @tparam string m The mode
function module.set_mode(m)
    assert(m == "live" or m == "after")
    mode = m
end

--- Add a initialization callback.
-- This callback will be executed before the mouse grabbing start
-- @tparam function cb The callback (or nil)
-- @tparam[default=other] string context The callback context
function module.add_enter_callback(cb, context)
    context = context or  "other"
    callbacks.enter[context] =  callbacks.enter[context] or {}
    table.insert(callbacks.enter[context], cb)
end

--- Add a "move" callback.
-- This callback is executed in "after" mode (see `set_mode`) instead of
-- applying the operation.
-- @tparam function cb The callback (or nil)
-- @tparam[default=other] string context The callback context
function module.add_move_callback(cb, context)
    context = context or  "other"
    callbacks.move[context] = callbacks.move[context]  or {}
    table.insert(callbacks.move[context], cb)
end

--- Add a "leave" callback
-- This callback is executed just before the `mousegrabber` stop
-- @tparam function cb The callback (or nil)
-- @tparam[default=other] string context The callback context
function module.add_leave_callback(cb, context)
    context = context or  "other"
    callbacks.leave[context] = callbacks.leave[context]  or {}
    table.insert(callbacks.leave[context], cb)
end

-- Resize, the drawable
--
-- Valid `args` are:
--
-- * *enter_callback*: A function called before the `mousegrabber` start
-- * *move_callback*: A function called when the mouse move
-- * *leave_callback*: A function called before the `mousegrabber` is released
-- * *mode*: The resize mode
--
-- @tparam client client A client
-- @tparam[default=mouse.resize] string context The resizing context
-- @tparam[opt={}] table args A set of `awful.placement` arguments
local function handler(_, client, context, args) --luacheck: no unused_args
    args = args or {}
    context = context or "mouse.resize"

    local placement = args.placement

    if type(placement) == "string" and aplace[placement] then
        placement = aplace[placement]
    end

    -- Extend the table with the default arguments
    args = setmetatable(
        {
            placement = placement or aplace.resize_to_mouse,
            mode      = args.mode or mode,
            pretend   = true,
        },
        {__index = args or {}}
    )

    local geo

    for _, cb in ipairs(callbacks.enter[context] or {}) do
        geo = cb(client, args)

        if geo == false then
            return false
        end
    end

    if args.enter_callback then
        geo = args.enter_callback(client, args)

        if geo == false then
            return false
        end
    end

    geo = nil

    -- Execute the placement function and use request::geometry
    capi.mousegrabber.run(function (_mouse)
        if not client.valid then return end

        -- Resize everytime the mouse move (default behavior)
        if args.mode == "live" then
            -- Get the new geometry
            geo = setmetatable(args.placement(client, args),{__index=args})
        end

        -- Execute the move callbacks. This can be used to add features such as
        -- snap or adding fancy graphical effects.
        for _, cb in ipairs(callbacks.move[context] or {}) do
            -- If something is returned, assume it is a modified geometry
            geo = cb(client, geo, args) or geo

            if geo == false then
                return false
            end
        end

        if args.move_callback then
            geo = args.move_callback(client, geo, args)

            if geo == false then
                return false
            end
        end

        -- In case it was modified
        setmetatable(geo,{__index=args})

        if args.mode == "live" then
            -- Ask the resizing handler to resize the client
            client:emit_signal( req, context, geo)
        end

        -- Quit when the button is released
        for _,v in pairs(_mouse.buttons) do
            if v then return true end
        end

        -- Only resize after the mouse is released, this avoid losing content
        -- in resize sensitive apps such as XTerm or allow external modules
        -- to implement custom resizing
        if args.mode == "after" then
            -- Get the new geometry
            geo = args.placement(client, args)

            -- Ask the resizing handler to resize the client
            client:emit_signal( req, context, geo)
        end

        geo = nil

        for _, cb in ipairs(callbacks.leave[context] or {}) do
            geo = cb(client, geo, args)
        end

        if args.leave_callback then
            geo = args.leave_callback(client, geo, args)
        end

        if not geo then return false end

        -- In case it was modified
        setmetatable(geo,{__index=args})

        client:emit_signal( req, context, geo)

        return false
    end, "cross")
end

return setmetatable(module, {__call=handler})