Namespace sap.ui.core.RendererModule: sap/ui/core/Renderer

Creates a new static renderer class that extends a given renderer.

This method can be used with two signatures that are explained below. In both variants, the returned renderer class inherits all properties (methods, fields) from the given parent renderer class. Both variants also add an 'extend' method to the created renderer class that behaves like the new signature of this Renderer.extend method, but creates subclasses of the new class, not of sap.ui.core.Renderer.

New Signature
In the new signature variant, two parameters must be given: a qualified name for the new renderer (its class name), and an optional object literal that contains methods or fields to be added to the new renderer class.

This signature has been designed to resemble the class extension mechanism as provided by Object.extend.

sap.ui.define(['sap/ui/core/Renderer'],
    function(Renderer) {
    "use strict";

    var LabelRenderer = Renderer.extend('sap.m.LabelRenderer', {
        renderer: function(oRM, oControl) {

            renderPreamble(oRM, oControl);

            // implementation core renderer logic here

            renderPreamble(oRM, oControl);

        },

        renderPreamble : function(oRM, oControl) {
        ...
        },

        renderPostamble : function(oRM, oControl) {
        ...
        }

    });

    return LabelRenderer;
});

The extension of Renderers works across multiple levels. A FancyLabelRenderer can extend the above LabelRenderer:

sap.ui.define(['sap/m/LabelRenderer'],
    function(LabelRenderer) {
    "use strict";

    var FancyLabelRenderer = LabelRenderer.extend('sap.mylib.FancyLabelRenderer', {
        renderer: function(oRM, oControl) {

            // call base renderer
            LabelRenderer.renderPreamble(oRM, oControl);

            // ... do your own fancy rendering here

            // call base renderer again
            LabelRenderer.renderPostamble(oRM, oControl);
        }
    });

    return FancyLabelRenderer;
});

Note: the new signature no longer requires the bExport flag to be set for the enclosing sap.ui.define call. The Renderer base classes takes care of the necessary global export of the render. This allows Non-SAP developers to write a renderer that complies with the documented restriction for sap.ui.define (no use of bExport = true outside sap.ui.core projects).

Deprecated Signature
The deprecated old signature expects just one parameter: a renderer that should be extended. With that signature the renderer can't be exported globally as the name of the renderer class is not known.

For compatibility reasons, the class created by the deprecated signature contains a property _super that references the parent class. It shouldn't be used by applications / control developers as it doesn't work reliably for deeper inheritance chains: if the old variant of Renderer.extend is used on two or more levels of the inheritance hierarchy, the _super property of the resulting renderer class will always point to the implementation of the base renderer of the last call to extend. Instead of using this._super, renderer implementations should use the new signature variant and access the base implementation of a method via the AMD reference to the base renderer (as shown in the FancyLabelRenderer example above).