Class StickyHeaderContainer

java.lang.Object
com.codename1.ui.Component
com.codename1.ui.Container
com.codename1.components.StickyHeaderContainer
All Implemented Interfaces:
Animation, Editable, StyleListener, Iterable<Component>
public class StickyHeaderContainer extends Container

A scrollable container that pins the most recently scrolled-past section header to the top of its viewport, in the style of the iOS contacts list or sectioned material lists. As the user scrolls past a section boundary the previous header is replaced by the next one through a configurable staged transition: a directional slide (slides up on forward scroll, down on reverse scroll) or a cross-fade. Transitions are time-driven so a slow scroll surfaces every animation frame at full duration while a fast scroll lets the latest swap supersede earlier in-flight ones.

Sections are added with addSection(header, content). The header is a real component that participates in the scroll: when it is the active section's header it is moved into a pinned overlay slot at the top of the container, and a same-sized invisible placeholder is left behind in the scroll content so nothing jumps. Because the pinned header is the same instance, action listeners and child components remain interactive while it is pinned.

StickyHeaderContainer sticky = new StickyHeaderContainer();
sticky.setTransitionStyle(StickyHeaderContainer.TRANSITION_SLIDE);
sticky.setTransitionDurationMillis(250);
for (char c = 'A'; c <= 'Z'; c++) {
    Label header = new Label("" + c, "StickyHeader");
    Container items = new Container(BoxLayout.y());
    for (int i = 0; i < 5; i++) {
        items.add(new Label(c + " entry " + i));
    }
    sticky.addSection(header, items);
}
form.add(BorderLayout.CENTER, sticky);

  • Field Details

    • TRANSITION_NONE

      public static final int TRANSITION_NONE
      Replace the pinned header without animation.
      See Also:

    • TRANSITION_SLIDE

      public static final int TRANSITION_SLIDE
      Slide the outgoing header out of the slot while the incoming header slides in. Forward scroll slides upward, reverse scroll slides downward.
      See Also:

    • TRANSITION_FADE

      public static final int TRANSITION_FADE
      Fade the outgoing header to transparency on top of the incoming one.
      See Also:

  • Constructor Details

    • StickyHeaderContainer

      public StickyHeaderContainer()
      Creates an empty sticky header container. Add sections via addSection(header, content).

  • Method Details

    • addSection

      public StickyHeaderContainer addSection(Component header, Component content)
      Adds a section consisting of a sticky header and its content. The content may be null for a header-only section. Returns this for chaining.

    • addSection

      public StickyHeaderContainer addSection(Component header)
      Adds a header-only section.

    • getScrollContainer

      public Container getScrollContainer()
      Returns the inner scrolling container that hosts the section content. Use this to add non-section components such as a footer, or for programmatic scrolling via setScrollPosition(int).

    • getStickyHost

      public Container getStickyHost()
      Returns the overlay container that hosts the currently-pinned header. While a section is active its header lives here; otherwise the host is empty and zero-height.

    • getStickyHeaders

      public List<Component> getStickyHeaders()
      Returns an unmodifiable view of the registered sticky headers in the order they were added.

    • getActiveSectionIndex

      public int getActiveSectionIndex()
      Returns the index of the currently pinned section, or -1 if no header is currently pinned.

    • setTransitionStyle

      public void setTransitionStyle(int style)
      Selects how the pinned header is replaced when the active section changes. One of TRANSITION_NONE, TRANSITION_SLIDE (default) or TRANSITION_FADE.

    • getTransitionStyle

      public int getTransitionStyle()

    • setTransitionDurationMillis

      public void setTransitionDurationMillis(int millis)
      Sets the duration of the header replacement animation in milliseconds. A value of 0 makes transitions instantaneous regardless of getTransitionStyle().

    • getTransitionDurationMillis

      public int getTransitionDurationMillis()

    • isTransitionInProgress

      public boolean isTransitionInProgress()
      Returns true while a header replacement animation is in progress.

    • getTransitionProgress

      public float getTransitionProgress()
      Returns the progress of the in-flight transition as a fraction in [0, 1]. Returns 1 when no transition is running.

    • setScrollPosition

      public void setScrollPosition(int y)
      Sets the scroll position of the inner scroll container. The value is clamped to the valid range and triggers a sticky-header recompute.

    • getScrollPosition

      public int getScrollPosition()
      Returns the current scroll position of the inner scroll container.

    • clearSections

      public void clearSections()
      Removes all sections and content from the container.

    • updateSticky

      public void updateSticky()
      Recomputes which section header should be pinned and updates the overlay accordingly. The container calls this internally on scroll; call it explicitly when section content has been mutated outside of a normal layout cycle.

    • animate

      public boolean animate()
      Description copied from class: Component

      Allows the animation to reduce "repaint" calls when it returns false. It is called once for every frame. Frames are defined by the com.codename1.ui.Display class.

      Returns

      true if a repaint is desired or false if no repaint is necessary

      Specified by:
      animate in interface Animation
      Overrides:
      animate in class Component

    • paint

      public void paint(Graphics g)
      Description copied from class: Container

      This method paints the Component on the screen, it should be overriden by subclasses to perform custom drawing or invoke the UI API's to let the PLAF perform the rendering.

      Parameters
      • g: the component graphics
      Specified by:
      paint in interface Animation
      Overrides:
      paint in class Container

    • paintGlass

      protected void paintGlass(Graphics g)
      Description copied from class: Container

      This method can be overriden by a component to draw on top of itself or its children after the component or the children finished drawing in a similar way to the glass pane but more refined per component

      Parameters
      • g: the graphics context
      Overrides:
      paintGlass in class Container

    • deinitialize

      protected void deinitialize()
      Description copied from class: Component
      Invoked to indicate that the component initialization is being reversed since the component was detached from the container hierarchy. This allows the component to deregister animators and cleanup after itself. This method is the opposite of the initComponent() method.
      Overrides:
      deinitialize in class Component