JScrollPaneでキネティックスクロール
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Posted by aterai at
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概要
JScrollPane
にキネティックスクロール(慣性スクロール)風の動作をするマウスリスナーを設定します。
Screenshot
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サンプルコード
class KineticScrollingListener2 extends MouseAdapter implements HierarchyListener {
protected static final int SPEED = 4;
protected static final int DELAY = 10;
protected static final double D = .8;
protected final JComponent label;
protected final Point startPt = new Point();
protected final Point delta = new Point();
protected final Cursor dc;
protected final Cursor hc = Cursor.getPredefinedCursor(Cursor.HAND_CURSOR);
protected final Timer inside = new Timer(DELAY, null);
protected final Timer outside = new Timer(DELAY, null);
protected static boolean isInside(JViewport viewport, JComponent comp) {
Point vp = viewport.getViewPosition();
return vp.x >= 0 && vp.x + viewport.getWidth() - comp.getWidth() <= 0
&& vp.y >= 0 && vp.y + viewport.getHeight() - comp.getHeight() <= 0;
}
protected KineticScrollingListener2(JComponent comp) {
super();
this.label = comp;
this.dc = comp.getCursor();
inside.addActionListener(e -> dragInside());
outside.addActionListener(e -> dragOutside());
}
private void dragInside() {
JViewport viewport = (JViewport) SwingUtilities.getUnwrappedParent(label);
Point vp = viewport.getViewPosition();
// System.out.format("s: %s, %s%n", delta, vp);
vp.translate(-delta.x, -delta.y);
viewport.setViewPosition(vp);
if (Math.abs(delta.x) > 0 || Math.abs(delta.y) > 0) {
delta.setLocation((int) (delta.x * D), (int) (delta.y * D));
// Outside
if (vp.x < 0 || vp.x + viewport.getWidth() - label.getWidth() > 0) {
delta.x = (int) (delta.x * D);
}
if (vp.y < 0 || vp.y + viewport.getHeight() - label.getHeight() > 0) {
delta.y = (int) (delta.y * D);
}
} else {
inside.stop();
if (!isInside(viewport, label)) {
outside.start();
}
}
}
private void dragOutside() {
JViewport viewport = (JViewport) SwingUtilities.getUnwrappedParent(label);
Point vp = viewport.getViewPosition();
// System.out.format("r: %s%n", vp);
if (vp.x < 0) {
vp.x = (int) (vp.x * D);
}
if (vp.y < 0) {
vp.y = (int) (vp.y * D);
}
if (vp.x + viewport.getWidth() - label.getWidth() > 0) {
vp.x = (int) (vp.x - (vp.x + viewport.getWidth() - label.getWidth()) * (1d - D));
}
if (vp.y + viewport.getHeight() > label.getHeight()) {
vp.y = (int) (vp.y - (vp.y + viewport.getHeight() - label.getHeight()) * (1d - D));
}
viewport.setViewPosition(vp);
if (isInside(viewport, label)) {
outside.stop();
}
}
@Override public void mousePressed(MouseEvent e) {
e.getComponent().setCursor(hc);
startPt.setLocation(e.getPoint());
inside.stop();
outside.stop();
}
@Override public void mouseDragged(MouseEvent e) {
Point pt = e.getPoint();
JViewport viewport = (JViewport) SwingUtilities.getUnwrappedParent(label);
Point vp = viewport.getViewPosition();
vp.translate(startPt.x - pt.x, startPt.y - pt.y);
viewport.setViewPosition(vp);
delta.setLocation(SPEED * (pt.x - startPt.x), SPEED * (pt.y - startPt.y));
startPt.setLocation(pt);
}
@Override public void mouseReleased(MouseEvent e) {
e.getComponent().setCursor(dc);
JViewport viewport = (JViewport) SwingUtilities.getUnwrappedParent(label);
if (isInside(viewport, label)) {
inside.start();
} else {
outside.start();
}
}
@Override public void hierarchyChanged(HierarchyEvent e) {
Component c = e.getComponent();
if ((e.getChangeFlags() & HierarchyEvent.DISPLAYABILITY_CHANGED) != 0
&& !c.isDisplayable()) {
inside.stop();
outside.stop();
}
}
}
View in GitHub: Java, Kotlin解説
scrollRectToVisible
- マウスがリリースされたらタイマーを起動し、
JComponent#scrollRectToVisible(Rectangle)
メソッドでスクロール
- マウスがリリースされたらタイマーを起動し、
setViewPosition
- マウスがリリースされたらタイマーを起動し、
JViewport#setViewPosition(Point)
メソッドでスクロール View
として設定されているJLabel
の外で移動が止まった(またはマウスがリリースされた)場合は、別のタイマーでJLabel
の縁まで戻る
- マウスがリリースされたらタイマーを起動し、