Merge remote-tracking branch 'upstream/master'

resolved conflicts with refactored structure

frontend/document/picdocument.lua

@@ -0,0 +1,31 @@
+local Document = require("document/document")
+-- DrawContext
+
+local PicDocument = Document:new{
+	_document = false,
+	dc_null = DrawContext.new(),
+}
+
+function PicDocument:init()
+	ok, self._document = pcall(pic.openDocument, self.file)
+	if not ok then
+		self.error_message = "failed to open jpeg image"
+		return
+	end
+
+	self.info.has_pages = true
+	self.info.configurable = false
+
+	self:readMetadata()
+end
+
+function PicDocument:readMetadata()
+	self.info.number_of_pages = 1
+end
+
+function PicDocument:register(registry)
+	registry:addProvider("jpeg", "application/jpeg", self)
+	registry:addProvider("jpg", "application/jpeg", self)
+end
+
+return PicDocument