The technical principle analysis of the technical principles of Android SUPPORT CARDVIEW V7 framework in the Java library
The technical principle analysis of the technical principles of Android SUPPORT CARDVIEW V7 framework in the Java library
Overview:
CardView is an important component in Android Support Library V7. It provides a custom card view to display a set of related information in the application.CardView can be used to create a card -type layout, so that applications have more modern and intuitive user interfaces.This article will in -depth analysis of the technical principles of the CardView V7 framework in the Java class library.
Original analysis:
1. CardView inheritance relationship: CardView is a class that inherits from Framelayout.Framelayout is a container view class that can overlap multiple sub -views on the interface.CardView provides a card style and decoration on the basis of Framelaayout.
2. CardView custom attributes: CardView provides a series of custom attributes that can be set in the XML layout file.These attributes include the background color of the card, the radius radius, the shadow effect, the interior distance, etc.You can implement these attributes to implement different styles of card views.
Example code:
<android.support.v7.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
card_view:cardBackgroundColor="#ffffff"
card_view:cardCornerRadius="8dp"
card_view:cardElevation="4dp"
card_view:cardUseCompatPadding="true">
<!-Add the sub-view that needs to be displayed in CardView->
</android.support.v7.widget.CardView>
3. CardView's drawing process: CardView will first draw the background color of the card when drawing, and then draw the boundary and shadow effect of the rounded rectangle.This drawing process is achieved by calling Canvas' drawroundRect () method.At the same time, CardView also sets the padding to control the spacing of the internal sub -view.
Example code:
protected void dispatchDraw(Canvas canvas) {
// Draw background color
super.dispatchDraw(canvas);
// Draw the rounded rectangular boundary and shadow effect
drawCardBackground(canvas);
}
private void drawCardBackground(Canvas canvas) {
// Use Canvas.DrawroundRect () Method to draw a rounded rectangular boundary
// Use Canvas.DrawRect () Method to draw shadow effects
}
// Set the inner border distance
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
// Set padding
}
4. CardView's sliding processing: CardView can achieve sliding operations, such as clicking, pressing, lifting and other gesture events.CardView will determine whether to trigger the clicks based on the coordinate position of the sliding event and provide a callback interface for developers to deal with it.
Example code:
protected void onInterceptTouchEvent(MotionEvent ev) {
// Determine the coordinate position of the click event
// When triggering the click event, call the PerformClick method
switch (action) {
case MotionEvent.ACTION_DOWN:
// Press the event
break;
case MotionEvent.ACTION_UP:
// Lift the event
break;
}
return super.onInterceptTouchEvent(ev);
}
public boolean performClick() {
// Treat the click event
return super.performClick();
}
in conclusion:
By analyzing the technical principles of Android Support Cardview V7 framework in the Java Library, we can understand key technical principles such as CardView's inheritance relationship, custom attributes, drawing processes, and sliding processing.Mastering these principles can help developers better use CardView components, realize card -type layouts that meet the design style, and enhance the user experience of the application.
