Merge pull request #3451 from Elv13/screenshot

Copy of  "Content (Screenshot) API Expansion"

lib/awful/screen.lua

@@ -19,6 +19,8 @@ local gdebug = require("gears.debug")
 local gmath = require("gears.math")
 local object = require("gears.object")
 local grect =  require("gears.geometry").rectangle
+local gsurf = require("gears.surface")
+local cairo = require("lgi").cairo
 
 local function get_screen(s)
     return s and capi.screen[s]
@@ -201,6 +203,25 @@ function screen.object.get_tiling_area(s)
     }
 end
 
+--- Take a screenshot of the physical screen.
+--
+-- Reading this (read only) property returns a screenshot of the physical
+-- (Xinerama) screen as a cairo surface.
+--
+-- @property content
+-- @tparam gears.surface content
+
+function screen.object.get_content(s)
+    local geo = s.geometry
+    local source = gsurf(root.content())
+    local target = source:create_similar(cairo.Content.COLOR, geo.width, geo.height)
+    local cr = cairo.Context(target)
+    cr:set_source_surface(source, -geo.x, -geo.y)
+    cr:rectangle(0, 0, geo.width, geo.height)
+    cr:fill()
+    return target
+end
+
 --- Get or set the screen padding.
 --
 -- @deprecated awful.screen.padding

root.c

@@ -500,6 +500,29 @@ luaA_root_wallpaper(lua_State *L)
     return 1;
 }
 
+
+/** Get the content of the root window as a cairo surface.
+ *
+ * @property content
+ * @tparam surface A cairo surface with the root window content (aka the whole surface from every screens).
+ * @see gears.surface
+ */
+static int
+luaA_root_get_content(lua_State *L)
+{
+    cairo_surface_t *surface;
+
+    surface = cairo_xcb_surface_create(globalconf.connection,
+                                       globalconf.screen->root,
+                                       globalconf.default_visual,
+                                       globalconf.screen->width_in_pixels, 
+                                       globalconf.screen->height_in_pixels);
+
+    lua_pushlightuserdata(L, surface);
+    return 1;
+}
+
+
 /** Get the size of the root window.
  *
  * @return Width of the root window.
@@ -608,6 +631,7 @@ const struct luaL_Reg awesome_root_methods[] =
     { "fake_input", luaA_root_fake_input },
     { "drawins", luaA_root_drawins },
     { "_wallpaper", luaA_root_wallpaper },
+    { "content", luaA_root_get_content},
     { "size", luaA_root_size },
     { "size_mm", luaA_root_size_mm },
     { "tags", luaA_root_tags },

tests/test-screenshot.lua

@@ -0,0 +1,165 @@
+-- This test suite tests the various screenshot related APIs.
+--
+-- Credit: https://www.reddit.com/r/awesomewm/comments/i6nf7z/need_help_writing_a_color_picker_widget_using_lgi/
+local wibox = require("wibox")
+local spawn = require("awful.spawn")
+local gsurface = require("gears.surface")
+local lgi = require 'lgi'
+local cairo = lgi.cairo
+local gdk = lgi.Gdk
+
+-- Dummy blue client for the client.content test
+-- the lua_executable portion may need to get ironed out. I need to specify 5.3
+local lua_executable = os.getenv("LUA")
+if lua_executable == nil or lua_executable == "" then
+    lua_executable = "lua5.3"
+end
+local client_dim = 250
+local tiny_client_code_template = [[
+local Gtk = require('lgi').Gtk
+local Gdk = require('lgi').Gdk
+local class = 'client'
+window = Gtk.Window {default_width=%d, default_height=%d, title='title'}
+window:set_wmclass(class, class)
+window:override_background_color(0,
+    Gdk.RGBA({red = 0, green = 0, blue = 1, alpha = 1}))
+window:show_all()
+Gtk:main{...}
+]]
+local tiny_client = { lua_executable, "-e", string.format(
+                          tiny_client_code_template, client_dim, client_dim)}
+
+-- Split in the screen into 2 distict screens.
+screen[1]:split()
+
+-- Add a green wibox on screen 1 at (100, 100)
+wibox {
+    bg      = "#00ff00",
+    visible = true,
+    width   = 100,
+    height  = 100,
+    x       = 100,
+    y       = 100,
+}
+
+local corners = {}
+
+-- Add red squares at 1 pixel away from each screen corners.
+for s in screen do
+    -- Top left
+    table.insert(corners, {
+        x = s.geometry.x + 1,
+        y = s.geometry.y + 1,
+    })
+
+    -- Top right
+    table.insert(corners, {
+        x = s.geometry.x + s.geometry.width - 11,
+        y = s.geometry.y + 1,
+    })
+
+    -- Bottom left
+    table.insert(corners, {
+        x = s.geometry.x + 1,
+        y = s.geometry.y + s.geometry.height - 11,
+    })
+
+    -- Bottom right
+    table.insert(corners, {
+        x = s.geometry.x + s.geometry.width - 11,
+        y = s.geometry.y + s.geometry.height - 11,
+    })
+
+end
+
+-- Make 10x10 wibox in each corner to eliminate any geometry errors
+for _, corner in ipairs(corners) do
+    corner.bg = "#ff0000"
+    corner.visible = true
+    corner.width = 10
+    corner.height = 10
+
+    wibox(corner)
+end
+
+local function copy_to_image_surface(content, w, h)
+    local sur = gsurface(content)
+
+    local img = cairo.ImageSurface(cairo.Format.RGB24, w, h)
+    local cr = cairo.Context(img)
+
+    cr:set_source_surface(sur)
+    cr:paint()
+    img:finish()
+
+    return img
+end
+
+local function get_pixel(img, x, y)
+    local bytes = gdk.pixbuf_get_from_surface(img, x, y, 1, 1):get_pixels()
+    return "#" .. bytes:gsub('.', function(c) return ('%02x'):format(c:byte()) end)
+end
+
+local steps = {}
+
+-- Check the whole root window.
+table.insert(steps, function()
+    local img = copy_to_image_surface(root.content(), root.size())
+    local root_width, root_height = root.size()
+
+    if get_pixel(img, 100, 100) ~= "#00ff00" then return end
+    if get_pixel(img, 2, 2) ~= "#ff0000" then return end
+
+    assert(get_pixel(img, 100, 100) == "#00ff00")
+    assert(get_pixel(img, 199, 199) == "#00ff00")
+    assert(get_pixel(img, 201, 201) ~= "#00ff00")
+
+    assert(get_pixel(img, 2, 2) == "#ff0000")
+    assert(get_pixel(img, root_width - 2, 2) == "#ff0000")
+    assert(get_pixel(img, 2, root_height - 2) == "#ff0000")
+    assert(get_pixel(img, root_width - 2, root_height - 2) == "#ff0000")
+
+    return true
+end)
+
+-- Check the screen.content
+table.insert(steps, function()
+    for s in screen do
+
+      local geo = s.geometry
+      local img = copy_to_image_surface(s.content, geo.width, geo.height)
+
+      assert(get_pixel(img, geo.x + 4, geo.y + 4) == "#ff0000")
+      assert(get_pixel(img, geo.x + geo.width - 4, geo.y + 4) == "#ff0000")
+      assert(get_pixel(img, geo.x + 4, geo.y + geo.height - 4) == "#ff0000")
+      assert(get_pixel(img, geo.x + geo.width - 4, geo.y + geo.height - 4) == "#ff0000")
+
+    end
+
+    -- Spawn for the client.content test
+    assert(#client.get() == 0)
+    spawn(tiny_client)
+
+    return true
+end)
+
+-- Check the client.content
+table.insert(steps, function()
+    if #client.get() ~= 1 then return end
+    local c = client.get()[1]
+    local geo = c:geometry()
+    local img = copy_to_image_surface(c.content, geo.width, geo.height)
+
+    if get_pixel(img, math.floor(geo.width / 2), math.floor(geo.height / 2)) ~= "#0000ff" then
+        return
+    end
+
+    -- Make sure the process finishes. Just `c:kill()` only
+    -- closes the window. Adding some handlers to the GTK "app"
+    -- created some unwanted side effects in the CI.
+    awesome.kill(c.pid, 9)
+
+    return true
+end)
+
+require("_runner").run_steps(steps)