How to expand the custom view function in Android Support Library
How to expand the custom view function in Android Support Library
Overview:
In Android development, custom view is a very useful way to create a unique and customized user interface.Android Support Library provides rich functions to expand custom views and can maintain compatibility on extensive Android devices.This article will introduce how to use Android Support Library to extend the custom view function and provide code examples.Here are some common custom view functions:
1. Attribute definition: Define some custom attributes for custom views to use in layout files or code.This can provide more flexibility for the view.The following is an example code:
<resources>
<declare-styleable name="CustomView">
<attr name="customColor" format="color"/>
</declare-styleable>
</resources>
2. Measurement and layout: By rewriting onMeaSure () and onlyout () methods, the size and location of the custom view can be controlled.The following is an example code:
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
// Calculate the measurement size of the view as needed
setMeasuredDimension(widthSize, heightSize);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
// Define the location and layout of the view here
}
3. Drawing: By rewriting the ONDraw () method, you can control the drawing of custom views.You can use Canvas and Paint objects for drawing operations.The following is an example code:
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Paint paint = new Paint();
// Perform drawing operations, such as drawing shape, text, etc.
}
4. Interaction: By handling touch events and gesture recognition, you can add interactive functions to custom view.The following is an example code:
@Override
public boolean onTouchEvent(MotionEvent event) {
// Touch the touch event, such as clicking, sliding, etc.
return super.onTouchEvent(event);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent event) {
// Treatment of incident interception, such as handling touch events in the father's view
return super.onInterceptTouchEvent(event);
}
5. Custom view combination: Create a more complex custom view through combination of multiple existing views or layouts.The following is an example code:
public class MyCustomView extends RelativeLayout {
public MyCustomView(Context context) {
super(context);
initView(context);
}
public MyCustomView(Context context, AttributeSet attrs) {
super(context, attrs);
initView(context);
initAttributes(attrs);
}
private void initView(Context context) {
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
inflater.inflate(R.layout.my_custom_view, this, true);
}
private void initAttributes(AttributeSet attrs) {
// Analysis of custom attributes
}
}
Through these methods, we can use custom view features in Android Support Library to expand our application.These features can help us achieve highly customized user interfaces on different Android devices and provide a better user experience.Hope this article will be helpful for your expansion of the custom view function.
Reference link:
- https://developer.android.com/guide/topics/ui/custom-components
- https://developer.android.com/training/custom-views
