Custom View Example

The CustomView sample in the API Demos provides an example of a customized View. The custom View is defined in the LabelView class.

The LabelView sample demonstrates a number of different aspects of custom components:

• Extending the View class for a completely custom component.

• Parameterized constructor that takes the view inflation parameters (parameters defined in the XML). Some of these are passed through to the View superclass, but more importantly, there are some custom attributes defined and used for LabelView.

• Standard public methods of the type you would expect to see for a label component, for example setText(), setTextSize(), setTextColor() and so on.

• An overridden onMeasure method to determine and set the rendering size of the component. (Note that in LabelView, the real work is done by a private measureWidth() method.)

• An overridden onDraw() method to draw the label onto the provided canvas.

You can see some sample usages of the LabelView custom View in custom view 1.xml from the samples. In particular, you can see a mix of both android: namespace parameters and custom app: namespace parameters. These app: parameters are the custom ones that the LabelView recognizes and works with, and are defined in a styleable inner class inside of the samples R resources definition class.

Was this article helpful?

0 0

Post a comment