io.github.palexdev.virtualizedfx.list.paginated.VFXPaginatedListManager Maven / Gradle / Ivy
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/*
* Copyright (C) 2024 Parisi Alessandro - [email protected]
* This file is part of VirtualizedFX (https://github.com/palexdev/VirtualizedFX)
*
* VirtualizedFX is free software: you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 3 of the License,
* or (at your option) any later version.
*
* VirtualizedFX is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with VirtualizedFX. If not, see
* This is necessary to respond to the following property changes introduced by the paginated variant:
*
- cells per page changes, {@link #onCellsPerPageChanged()}
*
- max page changes, {@link #onMaxPageChanged()}
*
* It also modifies some of the behaviors already defined in {@link VFXListManager} because the paginated variant should
* respond differently in some cases, and also to optimize performance as much as possible.
*/
public class VFXPaginatedListManager> extends VFXListManager {
//================================================================================
// Constructors
//================================================================================
public VFXPaginatedListManager(VFXPaginatedList list) {
super(list);
}
//================================================================================
// Methods
//================================================================================
/**
* A paginated container's size strictly depends on how many cells/rows/items is set to display per page, and this
* is enforced by the default skin {@link VFXPaginatedListSkin}, see {@link VFXPaginatedListSkin#getLength()}.
*
* This core method is called whenever the {@link VFXPaginatedList#cellsPerPageProperty()} changes and ensures that
* the layout bounds of the container become invalid ({@link Parent#isNeedsLayout()} becomes 'true'), by calling
* {@link Parent#requestLayout()}.
*
* This way, computations that also rely on the container size become invalid too, thus leading to correct values.
*/
protected void onCellsPerPageChanged() {
VFXList list = getNode();
list.requestLayout();
}
/**
* This core method ensures that the paginated container is always at a valid page/position when the
* {@link VFXPaginatedList#maxPageProperty()} changes.
*
* The only one case this needs to correct the position is when the current page is greater than the new max page.
* (both in terms of indexes ofc).
*
* Important note: the page change would trigger a position change (so {@link #onPositionChanged()}), but this
* method avoids it by setting the {@link #invalidatingPos} flag to 'true' before and immediately re-setting it to false
* after. This may sound counterintuitive, but there is a reason.
*
* You see, the max page property can change on two occasions:
*
1) the number of items changes
*
2) the cells per page changes
*
* BUT... in the first case, we have a change in the list which is handled by {@link #onItemsChanged()};
* and the second case is handled by {@link #onGeometryChanged()}. This last case is very peculiar, because it will work
* only if the container's skin is implemented to adapt to the number of items per page. It's the skin's implementation
* to trigger the geometry change, and this should be the intended default behavior.
*
* If you want to make a skin that doesn't follow this logic, then you probably want to change this method too.
*/
protected void onMaxPageChanged() {
VFXPaginatedList list = getNode();
int page = list.getPage();
int max = list.getMaxPage();
if (page > max) {
invalidatingPos = true;
list.moveBy(0);
invalidatingPos = false;
}
}
//================================================================================
// Overridden Methods
//================================================================================
/**
* Overridden to just call {@link VFXList#requestViewportLayout()}.
*
* For the paginated variant, the cells' size is irrelevant for its state. The default behavior, also dependent on
* the skin, is to adapt the container's size to the size of each cell as well as the number of cells per page.
*/
@Override
protected void onCellSizeChanged() {
VFXList list = getNode();
list.requestViewportLayout();
}
/**
* As also described in the super method ({@link VFXListManager#onOrientationChanged()}), when the orientation changes
* the most reasonable behavior is to reset both the positions to 0.0. For the paginated variant this requires extra
* steps because, according to the previous orientation, the vPos or hPos properties are bound. Also, the reset also
* requires setting the page to 0.
*/
@Override
protected void onOrientationChanged() {
VFXPaginatedList list = getNode();
list.vPosProperty().unbind();
list.hPosProperty().unbind();
list.setPage(0);
super.onOrientationChanged();
}
/**
* Overridden to cast to {@link VFXPaginatedList} since this behavior only allows that type.
*/
@Override
public VFXPaginatedList getNode() {
return (VFXPaginatedList) super.getNode();
}
}