---
category: swing
folder: ReorderingLayer
title: JLayerを使用してコンポーネントの並べ替えを行う
tags: [JLayer, DragAndDrop, BoxLayout]
author: aterai
pubdate: 2015-04-06T00:00:32+09:00
description: JPanel内に配置したコンポーネントの並べ替えで、ドラッグ中のコンポーネントをJLayerで描画します。
image: https://lh3.googleusercontent.com/-gW9pryNmoYY/VSFFArmXElI/AAAAAAAAN2A/CYZqhoCR0EE/s800/ReorderingLayer.png
---
* Summary [#summary]
`JPanel`内に配置したコンポーネントの並べ替えで、ドラッグ中のコンポーネントを`JLayer`で描画します。
#download(https://lh3.googleusercontent.com/-gW9pryNmoYY/VSFFArmXElI/AAAAAAAAN2A/CYZqhoCR0EE/s800/ReorderingLayer.png)
* Source Code Examples [#sourcecode]
#code(link){{
class ReorderingLayerUI<V extends JComponent> extends LayerUI<V> {
private static final Rectangle TOP_HALF_RECT = new Rectangle();
private static final Rectangle BOTTOM_HALF_RECT = new Rectangle();
private static final Rectangle INNER_RECT = new Rectangle();
private static final Rectangle PREV_RECT = new Rectangle();
private static final Rectangle DRAGGING_RECT = new Rectangle();
private final Point startPt = new Point();
private final Point dragOffset = new Point();
private final Container canvas = new JPanel();
private final int gestureMotionThreshold = DragSource.getDragThreshold();
private Component draggingComponent;
private Component fillerComponent;
@Override public void paint(Graphics g, JComponent c) {
super.paint(g, c);
if (c instanceof JLayer && Objects.nonNull(draggingComponent)) {
SwingUtilities.paintComponent(g, draggingComponent, canvas, DRAGGING_RECT);
}
}
@Override public void installUI(JComponent c) {
super.installUI(c);
if (c instanceof JLayer) {
((JLayer<?>) c).setLayerEventMask(AWTEvent.MOUSE_EVENT_MASK | AWTEvent.MOUSE_MOTION_EVENT_MASK);
}
}
@Override public void uninstallUI(JComponent c) {
if (c instanceof JLayer) {
((JLayer<?>) c).setLayerEventMask(0);
}
super.uninstallUI(c);
}
@Override protected void processMouseEvent(MouseEvent e, JLayer<? extends V> l) {
JComponent parent = l.getView();
switch (e.getID()) {
case MouseEvent.MOUSE_PRESSED:
if (parent.getComponentCount() > 0) {
startPt.setLocation(e.getPoint());
l.repaint();
}
break;
case MouseEvent.MOUSE_RELEASED:
if (Objects.nonNull(draggingComponent)) {
// swap the dragging panel and the temporary filler
int idx = parent.getComponentZOrder(fillerComponent);
replaceComponents(parent, fillerComponent, draggingComponent, idx);
draggingComponent = null;
}
break;
default:
break;
}
}
@Override protected void processMouseMotionEvent(MouseEvent e, JLayer<? extends V> l) {
if (e.getID() == MouseEvent.MOUSE_DRAGGED) {
mouseDragged(l.getView(), e.getPoint());
l.repaint();
}
}
private void mouseDragged(JComponent parent, Point pt) {
if (Objects.isNull(draggingComponent)) {
// MotionThreshold
if (startPt.distance(pt) > gestureMotionThreshold) {
startDragging(parent, pt);
}
return;
}
// update the filler panel location
if (!PREV_RECT.contains(pt)) {
updateFillerLocation(parent, fillerComponent, pt);
}
// update the dragging panel location
updateDraggingPanelLocation(parent, pt, dragOffset);
}
private void startDragging(JComponent parent, Point pt) {
Component c = parent.getComponentAt(pt);
int index = parent.getComponentZOrder(c);
if (Objects.equals(c, parent) || index < 0) {
return;
}
draggingComponent = c;
Rectangle r = draggingComponent.getBounds();
DRAGGING_RECT.setBounds(r); // save draggingComponent size
dragOffset.setLocation(pt.x - r.x, pt.y - r.y);
fillerComponent = Box.createRigidArea(r.getSize());
replaceComponents(parent, c, fillerComponent, index);
updateDraggingPanelLocation(parent, pt, dragOffset);
}
private static void updateDraggingPanelLocation(JComponent parent, Point pt, Point dragOffset) {
Insets i = parent.getInsets();
Rectangle r = SwingUtilities.calculateInnerArea(parent, INNER_RECT);
int x = r.x;
int y = pt.y - dragOffset.y;
int h = DRAGGING_RECT.height;
int yy;
if (y < i.top) {
yy = i.top;
} else {
yy = r.contains(x, y + h) ? y : r.height + i.top - h;
}
DRAGGING_RECT.setLocation(x, yy);
}
private static void updateFillerLocation(Container parent, Component filler, Point pt) {
// change the temporary filler location
for (int i = 0; i < parent.getComponentCount(); i++) {
Component c = parent.getComponent(i);
Rectangle r = c.getBounds();
if (Objects.equals(c, filler) && r.contains(pt)) {
return;
}
int tgt = getTargetIndex(r, pt, i);
if (tgt >= 0) {
replaceComponents(parent, filler, filler, tgt);
return;
}
}
}
private static int getTargetIndex(Rectangle r, Point pt, int i) {
int ht2 = (int) (.5 + r.height * .5);
TOP_HALF_RECT.setBounds(r.x, r.y, r.width, ht2);
BOTTOM_HALF_RECT.setBounds(r.x, r.y + ht2, r.width, ht2);
if (TOP_HALF_RECT.contains(pt)) {
PREV_RECT.setBounds(TOP_HALF_RECT);
return i > 1 ? i : 0;
} else if (BOTTOM_HALF_RECT.contains(pt)) {
PREV_RECT.setBounds(BOTTOM_HALF_RECT);
return i;
}
return -1;
}
private static void replaceComponents(Container parent, Component remove, Component insert, int idx) {
parent.remove(remove);
parent.add(insert, idx);
parent.revalidate();
parent.repaint();
}
}
}}
* Description [#explanation]
* Description [#description]
上記のサンプルの並べ替えの処理などは[[JPanelの並び順をドラッグ＆ドロップで入れ替える>Swing/RearrangeOrderOfPanels]]とほぼ同じものを使用していますが、こちらはドラッグ中のコンポーネントの移動可能領域を親の`JPanel`内のみに制限しているので`JWindow`ではなく`JLayer`を使用します。
- ドラッグ中のコンポーネントの位置・サイズ
-- 位置: 親の`JPanel`から内部余白を除いた部分をドラッグ可能な領域(`SwingUtilities.calculateInnerArea(...)`で取得)に設定し、その範囲内に位置を制限
-- サイズ: `LayerUI#paint(...)`内でのドラッグ中のコンポーネントの描画には、`SwingUtilities.paintComponent(...)`を使用しているが、この時ドラッグ中のコンポーネントは親の`JPanel`の子ではなくなっているため、`getSize()`で大きさを取得できない
--- そのためドラッグ開始前にそのサイズを別途記憶しておく必要がある
* Reference [#reference]
- [[JPanelの並び順をドラッグ＆ドロップで入れ替える>Swing/RearrangeOrderOfPanels]]
* Comment [#comment]
#comment
- `src.zip`などがダウンロードできない不具合を修正。 -- &user(aterai); &new{2015-04-20 (月) 17:57:58};
#comment