As I described in the latest entry, with the KDE Plasma Workspace 4.6 there will be a new feature that will be a key one for the future evolution of the Plasma platform: the ability to write plasmoids with just QML and Javascript.<\/p>\n
So, let’s try to see if it’s possible rewrite the average widget in with the declarative scriptengine…<\/p>\n
We have a dataengine (using a neat library called Attica) that can query the various functionalities of websites that offer an API compatible with the Open Collaboration Services, such as OpenDesktop.org<\/a>. One of the features offered by this API is the Knowledge Base: users subscribed to the site can ask any question (in topic with the website) and other users can answer to them. Plasma offers a desktop widget<\/a> that can query and visualize those question\/answers. It’s written in c++ and is about 400-500 lines of code.<\/p>\n How much QML code would take to write a very minimal Declarative Plasmoid that can access the knowledge base entries trough the Plasma dataengine? Here it is<\/p>\n 24 lines \ud83d\ude09<\/p>\n What is important to look here is the DataSource{} definition that defines to what engine we’re connecting and to what source. And the DataModel{} that hooks up what has been fetched by the DataSource to a suitable model for the use by the ListView.<\/p>\n Let’s expand from this to something that can be compared to the C++ version in terms of functionality. You can download an early example of the code from here<\/a>. (all is available from the playground<\/a> svn repo). It’s still early to include it in the 4.6 release for various reasons, but the path is definitely clear \ud83d\ude42<\/p>\n Here you can see a brief screencast of the two plasmoids, the C++ and the declarative one working side by side.<\/p>\n\nimport Qt 4.7\nimport org.kde.plasma.core 0.1 as PlasmaCore\n\nListView {\n clip: true\n width: 200\n height: 300\n\n PlasmaCore.DataSource {\n id: source\n engine: \"ocs\"\n source: \"KnowledgeBaseList\\provider:https:\/\/api.opendesktop.org\/v1\/\\query:opendesktop\\sortMode:new\\page:0\\pageSize:10\"\n interval: 120000\n }\n\n model: PlasmaCore.DataModel {\n dataSource: source\n key: \"KnowledgeBase-[\\d]*\"\n }\n\n delegate: Text {\n text: Name\n }\n}\n<\/pre>\n