JList ViewportLayout and scrollRectToVisible
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JList ViewportLayout and scrollRectToVisible
by i30817
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I did my own layout for the JScrollPane viewport, but replacing it seems to make a (core ?) bug visible in JList. Whenever the user uses the keyboard to move the selected cell, the viewport jumps from the left-origin to the center (the layout is centered). I "solved" it by disabling keyboard navigation by no-oping scrollRectToVisible, but if you can help me find the bug i would be grateful.
Here is my layout, it is made to be used with HORIZONTAL_WRAP orientation.
public static final class CenteredViewPortLayout implements LayoutManager {
public void addLayoutComponent(String name, Component comp) {/*nop*/
}
public void removeLayoutComponent(Component comp) {/*nop*/
}
public Dimension maximumLayoutSize(Container target) {
if (target == null) {
return new Dimension(0, 0);
}
return target.getPreferredSize();
}
public Dimension preferredLayoutSize(Container parent) {
Component view = ((JViewport) parent).getView();
if (view == null) {
return new Dimension(0, 0);
} else if (view instanceof Scrollable) {
return ((Scrollable) view).getPreferredScrollableViewportSize();
} else {
return view.getPreferredSize();
}
}
public Dimension minimumLayoutSize(Container parent) {
return new Dimension(4, 4);
}
public void layoutContainer(Container parent) {
JViewport vp = (JViewport) parent;
Component view = vp.getView();
if (view == null) {
return;
}
/**
* All of the dimensions below are in view coordinates.
*/
Dimension newViewSize = view.getPreferredSize();
Dimension maximumViewSize = vp.toViewCoordinates(vp.getSize());
/**
* If a JList the prefered size is the prefered size of the
* sum of cells fitting in a row.
* Also, the limit is the number of cells.
*/
if (view instanceof JList) {
int fixedCellWidth = ((JList) view).getFixedCellWidth();
int expandLimit = ((JList) view).getModel().getSize();
if (fixedCellWidth != -1) {
newViewSize.width = fixedCellWidth;
}
/**
* Multiply the cell width until it matches the
* n * viewPreferredSize.width + z = viewPort.width
* for a z < preferredSize and n <= expandLimit
*/
int n = 0;
while (((n + 1) * newViewSize.width) <= maximumViewSize.width && (n + 1) <= expandLimit) {
n++;
}
newViewSize.width = n * newViewSize.width;
}
//fill to maximum size if it doesn't fit or nothing there
if (newViewSize.width == 0) {
newViewSize.width = maximumViewSize.width;
}
/**_________ __________
* |X|XYX|Y| -> |X|YYYY|X|
* |X|XYX|Y| |X|YYYY|X|
*/
Point viewPosition = vp.getViewPosition();
int centerJustifiedX = (maximumViewSize.width - newViewSize.width) / 2;
viewPosition.x = -Math.max(0, centerJustifiedX);
vp.setViewPosition(viewPosition);
vp.setViewSize(newViewSize);
}
}
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Re: JList ViewportLayout and scrollRectToVisible
by James Lemieux
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This isn't a Glazed Lists bug, so it's best posted to some other Swing-specific forum, such as SUN's Java forums.
On Tue, Aug 11, 2009 at 3:48 PM, i30817 <i30817@...> wrote: I did my own layout for the JScrollPane viewport, but replacing it seems to make a (core ?) bug visible in JList. Whenever the user uses the keyboard to move the selected cell, the viewport jumps from the left-origin to the center (the layout is centered). I "solved" it by disabling keyboard navigation by no-oping scrollRectToVisible, but if you can help me find the bug i would be grateful. Here is my layout, it is made to be used with HORIZONTAL_WRAP orientation. |
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Re: JList ViewportLayout and scrollRectToVisible
by i30817
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You obviously never posted anything in those pits of newbie developers.
Besides this is where the List experts hangout. |
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