imagebox: Better svg support (#2779)

Use rsvg api to render svg image at requested size.

lib/wibox/widget/imagebox.lua

@@ -6,20 +6,53 @@
 -- @widgetmod wibox.widget.imagebox
 ---------------------------------------------------------------------------
 
+local lgi = require("lgi")
+local cairo = lgi.cairo
+
 local base = require("wibox.widget.base")
 local surface = require("gears.surface")
 local gtable = require("gears.table")
+local gdebug = require("gears.debug")
 local setmetatable = setmetatable
 local type = type
-local print = print
+local math = math
+
 local unpack = unpack or table.unpack -- luacheck: globals unpack (compatibility with Lua 5.1)
 
+-- Safe load for optional Rsvg module
+local Rsvg = nil
+do
+    local success, err = pcall(function() Rsvg = lgi.Rsvg end)
+    if not success then
+        gdebug.print_warning(debug.traceback("Could not load Rsvg: " .. tostring(err)))
+    end
+end
+
 local imagebox = { mt = {} }
 
+local rsvg_handle_cache = setmetatable({}, { __mode = 'v' })
+
+---Load rsvg handle form image file
+---@tparam string file Path to svg file.
+---@return Rsvg handle
+local function load_rsvg_handle(file)
+    if not Rsvg then return end
+
+    local cache = rsvg_handle_cache[file]
+    if cache then
+        return cache
+    end
+
+    local handle, err = Rsvg.Handle.new_from_file(file)
+    if not err then
+        rsvg_handle_cache[file] = handle
+        return handle
+    end
+end
+
 -- Draw an imagebox with the given cairo context in the given geometry.
 function imagebox:draw(_, cr, width, height)
-    if not self._private.image then return end
+    if width == 0 or height == 0 or not self._private.default then return end
-    if width == 0 or height == 0 then return end
 
     -- Set the clip
     if self._private.clip_shape then
@@ -28,86 +61,101 @@ function imagebox:draw(_, cr, width, height)
 
     if not self._private.resize_forbidden then
         -- Let's scale the image so that it fits into (width, height)
-        local w = self._private.image:get_width()
+        local w, h = self._private.default.width, self._private.default.height
-        local h = self._private.image:get_height()
+        local aspect = math.min(width / w, height / h)
-        local aspect = width / w
-        local aspect_h = height / h
-        if aspect > aspect_h then aspect = aspect_h end
-
         cr:scale(aspect, aspect)
     end
 
+    if self._private.handle then
+        self._private.handle:render_cairo(cr)
+    else
         cr:set_source_surface(self._private.image, 0, 0)
         cr:paint()
     end
+end
 
 -- Fit the imagebox into the given geometry
 function imagebox:fit(_, width, height)
-    if not self._private.image then
+    if not self._private.default then return 0, 0 end
-        return 0, 0
+    local w, h = self._private.default.width, self._private.default.height
-    end
 
-    local w = self._private.image:get_width()
+    if not self._private.resize_forbidden or w > width or h > height then
-    local h = self._private.image:get_height()
+        local aspect = math.min(width / w, height / h)
-
+        return w * aspect, h * aspect
-    if w > width then
-        h = h * width / w
-        w = width
-    end
-    if h > height then
-        w = w * height / h
-        h = height
-    end
-
-    if h == 0 or w == 0 then
-        return 0, 0
-    end
-
-    if not self._private.resize_forbidden then
-        local aspect = width / w
-        local aspect_h = height / h
-
-        -- Use the smaller one of the two aspect ratios.
-        if aspect > aspect_h then aspect = aspect_h end
-
-        w, h = w * aspect, h * aspect
     end
 
     return w, h
 end
 
---- Set an imagebox' image
+---Apply cairo surface for given imagebox widget
--- @property image
+local function set_surface(ib, surf)
--- @param image Either a string or a cairo image surface. A string is
+    local is_surd_valid = surf.width > 0 and surf.height > 0
---   interpreted as the path to a png image file.
+    if not is_surd_valid then return end
--- @return true on success, false if the image cannot be used
 
-function imagebox:set_image(image)
+    ib._private.default = { width = surf.width, height = surf.height }
-    if type(image) == "string" then
+    ib._private.handle = nil
-        image = surface.load(image)
+    ib._private.image = surf
-        if not image then
-            print(debug.traceback())
-            return false
-        end
-    end
-
-    image = image and surface.load(image)
-
-    if image then
-        local w = image.width
-        local h = image.height
-        if w <= 0 or h <= 0 then
-            return false
-        end
-    end
-
-    if self._private.image == image then
-        -- The image could have been modified, so better redraw
-        self:emit_signal("widget::redraw_needed")
     return true
 end
 
-    self._private.image = image
+---Apply RsvgHandle for given imagebox widget
+local function set_handle(ib, handle)
+    local dim = handle:get_dimensions()
+    local is_handle_valid = dim.width > 0 and dim.height > 0
+    if not is_handle_valid then return end
+
+    ib._private.default = { width = dim.width, height = dim.height }
+    ib._private.handle = handle
+    ib._private.image = nil
+    return true
+end
+
+---Try to load some image object from file then apply it to imagebox.
+---@tparam table ib Imagebox
+---@tparam string file Image file name
+---@tparam function image_loader Function to load image object from file
+---@tparam function image_setter Function to set image object to imagebox
+---@treturn boolean True if image was successfully applied
+local function load_and_apply(ib, file, image_loader, image_setter)
+    local image_applied
+    local object = image_loader(file)
+    if object then
+        image_applied = image_setter(ib, object)
+    end
+    return image_applied
+end
+
+--- Set an imagebox' image
+-- @property image
+-- @param image This can can be string, cairo image surface, rsvg handle object or nil. A string is
+--   interpreted as the path to an image file. Nil will deny previously set image.
+-- @return true on success, false if the image cannot be used
+function imagebox:set_image(image)
+    local setup_succeed
+
+    if type(image) == "string" then
+        -- try to load rsvg handle from file
+        setup_succeed = load_and_apply(self, image, load_rsvg_handle, set_handle)
+
+        if not setup_succeed then
+            -- rsvg handle failed, try to load cairo surface with pixbuf
+            setup_succeed = load_and_apply(self, image, surface.load, set_surface)
+        end
+    elseif Rsvg and Rsvg.Handle:is_type_of(image) then
+        -- try to apply given rsvg handle
+        setup_succeed = set_handle(self, image)
+    elseif cairo.Surface:is_type_of(image) then
+        -- try to apply given cairo surface
+        setup_succeed = set_surface(self, image)
+    elseif not image then
+        -- nil as argument mean full imagebox reset
+        setup_succeed = true
+        self._private.handle = nil
+        self._private.image = nil
+        self._private.default = nil
+    end
+
+    if not setup_succeed then return false end
 
     self:emit_signal("widget::redraw_needed")
     self:emit_signal("widget::layout_changed")
@@ -143,7 +191,6 @@ end
 -- @property resize
 -- @param allowed If false, the image will be clipped, else it will be resized
 --   to fit into the available space.
-
 function imagebox:set_resize(allowed)
     self._private.resize_forbidden = not allowed
     self:emit_signal("widget::redraw_needed")