 public void layoutContainer(Container parent) {
/* Sync the (now obsolete) policy fields with the
* JScrollPane.
*/
JScrollPane scrollPane = (JScrollPane)parent;
vsbPolicy = scrollPane.getVerticalScrollBarPolicy();
hsbPolicy = scrollPane.getHorizontalScrollBarPolicy();
Rectangle availR = scrollPane.getBounds();
availR.x = availR.y = 0;
Insets insets = parent.getInsets();
availR.x = insets.left;
availR.y = insets.top;
availR.width -= insets.left + insets.right;
availR.height -= insets.top + insets.bottom;
/* Get the scrollPane's orientation.
*/
boolean leftToRight = SwingUtilities.isLeftToRight(scrollPane);
/* If there's a visible column header remove the space it
* needs from the top of availR. The column header is treated
* as if it were fixed height, arbitrary width.
*/
Rectangle colHeadR = new Rectangle(0, availR.y, 0, 0);
if ((colHead != null) && (colHead.isVisible())) {
int colHeadHeight = Math.min(availR.height,
colHead.getPreferredSize().height);
colHeadR.height = colHeadHeight;
availR.y += colHeadHeight;
availR.height -= colHeadHeight;
}
/* If there's a visible row header remove the space it needs
* from the left or right of availR. The row header is treated
* as if it were fixed width, arbitrary height.
*/
Rectangle rowHeadR = new Rectangle(0, 0, 0, 0);
if ((rowHead != null) && (rowHead.isVisible())) {
int rowHeadWidth = Math.min(availR.width,
rowHead.getPreferredSize().width);
rowHeadR.width = rowHeadWidth;
availR.width -= rowHeadWidth;
if ( leftToRight ) {
rowHeadR.x = availR.x;
availR.x += rowHeadWidth;
} else {
rowHeadR.x = availR.x + availR.width;
}
}
/* If there's a JScrollPane.viewportBorder, remove the
* space it occupies for availR.
*/
Border viewportBorder = scrollPane.getViewportBorder();
Insets vpbInsets;
if (viewportBorder != null) {
vpbInsets = viewportBorder.getBorderInsets(parent);
availR.x += vpbInsets.left;
availR.y += vpbInsets.top;
availR.width -= vpbInsets.left + vpbInsets.right;
availR.height -= vpbInsets.top + vpbInsets.bottom;
}
else {
vpbInsets = new Insets(0,0,0,0);
}
/* At this point availR is the space available for the viewport
* and scrollbars. rowHeadR is correct except for its height and y
* and colHeadR is correct except for its width and x. Once we're
* through computing the dimensions of these three parts we can
* go back and set the dimensions of rowHeadR.height, rowHeadR.y,
* colHeadR.width, colHeadR.x and the bounds for the corners.
*
* We'll decide about putting up scrollbars by comparing the
* viewport views preferred size with the viewports extent
* size (generally just its size). Using the preferredSize is
* reasonable because layout proceeds top down - so we expect
* the viewport to be laid out next. And we assume that the
* viewports layout manager will give the view it's preferred
* size. One exception to this is when the view implements
* Scrollable and Scrollable.getViewTracksViewport{Width,Height}
* methods return true. If the view is tracking the viewports
* width we don't bother with a horizontal scrollbar, similarly
* if view.getViewTracksViewport(Height) is true we don't bother
* with a vertical scrollbar.
*/
Component view = (viewport != null) ? viewport.getView() : null;
Dimension viewPrefSize =
(view != null) ? view.getPreferredSize()
: new Dimension(0,0);
Dimension extentSize =
(viewport != null) ? viewport.toViewCoordinates(availR.getSize())
: new Dimension(0,0);
boolean viewTracksViewportWidth = false;
boolean viewTracksViewportHeight = false;
boolean isEmpty = (availR.width < 0 || availR.height < 0);
Scrollable sv;
// Don't bother checking the Scrollable methods if there is no room
// for the viewport, we aren't going to show any scrollbars in this
// case anyway.
if (!isEmpty && view instanceof Scrollable) {
sv = (Scrollable)view;
viewTracksViewportWidth = sv.getScrollableTracksViewportWidth();
viewTracksViewportHeight = sv.getScrollableTracksViewportHeight();
}
else {
sv = null;
}
/* If there's a vertical scrollbar and we need one, allocate
* space for it (we'll make it visible later). A vertical
* scrollbar is considered to be fixed width, arbitrary height.
*/
Rectangle vsbR = new Rectangle(0, availR.y - vpbInsets.top, 0, 0);
boolean vsbNeeded;
if (isEmpty) {
vsbNeeded = false;
}
else if (vsbPolicy == VERTICAL_SCROLLBAR_ALWAYS) {
vsbNeeded = true;
}
else if (vsbPolicy == VERTICAL_SCROLLBAR_NEVER) {
vsbNeeded = false;
}
else { // vsbPolicy == VERTICAL_SCROLLBAR_AS_NEEDED
vsbNeeded = !viewTracksViewportHeight && (viewPrefSize.height > extentSize.height);
}
if ((vsb != null) && vsbNeeded) {
adjustForVSB(true, availR, vsbR, vpbInsets, leftToRight);
extentSize = viewport.toViewCoordinates(availR.getSize());
}
/* If there's a horizontal scrollbar and we need one, allocate
* space for it (we'll make it visible later). A horizontal
* scrollbar is considered to be fixed height, arbitrary width.
*/
Rectangle hsbR = new Rectangle(availR.x - vpbInsets.left, 0, 0, 0);
boolean hsbNeeded;
if (isEmpty) {
hsbNeeded = false;
}
else if (hsbPolicy == HORIZONTAL_SCROLLBAR_ALWAYS) {
hsbNeeded = true;
}
else if (hsbPolicy == HORIZONTAL_SCROLLBAR_NEVER) {
hsbNeeded = false;
}
else { // hsbPolicy == HORIZONTAL_SCROLLBAR_AS_NEEDED
hsbNeeded = !viewTracksViewportWidth && (viewPrefSize.width > extentSize.width);
}
if ((hsb != null) && hsbNeeded) {
adjustForHSB(true, availR, hsbR, vpbInsets);
/* If we added the horizontal scrollbar then we've implicitly
* reduced the vertical space available to the viewport.
* As a consequence we may have to add the vertical scrollbar,
* if that hasn't been done so already. Of course we
* don't bother with any of this if the vsbPolicy is NEVER.
*/
if ((vsb != null) && !vsbNeeded &&
(vsbPolicy != VERTICAL_SCROLLBAR_NEVER)) {
extentSize = viewport.toViewCoordinates(availR.getSize());
vsbNeeded = viewPrefSize.height > extentSize.height;
if (vsbNeeded) {
adjustForVSB(true, availR, vsbR, vpbInsets, leftToRight);
}
}
}
/* Set the size of the viewport first, and then recheck the Scrollable
* methods. Some components base their return values for the Scrollable
* methods on the size of the Viewport, so that if we don't
* ask after resetting the bounds we may have gotten the wrong
* answer.
*/
if (viewport != null) {
viewport.setBounds(availR);
if (sv != null) {
extentSize = viewport.toViewCoordinates(availR.getSize());
boolean oldHSBNeeded = hsbNeeded;
boolean oldVSBNeeded = vsbNeeded;
viewTracksViewportWidth = sv.
getScrollableTracksViewportWidth();
viewTracksViewportHeight = sv.
getScrollableTracksViewportHeight();
if (vsb != null && vsbPolicy == VERTICAL_SCROLLBAR_AS_NEEDED) {
boolean newVSBNeeded = !viewTracksViewportHeight &&
(viewPrefSize.height > extentSize.height);
if (newVSBNeeded != vsbNeeded) {
vsbNeeded = newVSBNeeded;
adjustForVSB(vsbNeeded, availR, vsbR, vpbInsets,
leftToRight);
extentSize = viewport.toViewCoordinates
(availR.getSize());
}
}
if (hsb != null && hsbPolicy ==HORIZONTAL_SCROLLBAR_AS_NEEDED){
boolean newHSBbNeeded = !viewTracksViewportWidth &&
(viewPrefSize.width > extentSize.width);
if (newHSBbNeeded != hsbNeeded) {
hsbNeeded = newHSBbNeeded;
adjustForHSB(hsbNeeded, availR, hsbR, vpbInsets);
if ((vsb != null) && !vsbNeeded &&
(vsbPolicy != VERTICAL_SCROLLBAR_NEVER)) {
extentSize = viewport.toViewCoordinates
(availR.getSize());
vsbNeeded = viewPrefSize.height >
extentSize.height;
if (vsbNeeded) {
adjustForVSB(true, availR, vsbR, vpbInsets,
leftToRight);
}
}
}
}
if (oldHSBNeeded != hsbNeeded ||
oldVSBNeeded != vsbNeeded) {
viewport.setBounds(availR);
// You could argue that we should recheck the
// Scrollable methods again until they stop changing,
// but they might never stop changing, so we stop here
// and don't do any additional checks.
}
}
}
/* We now have the final size of the viewport: availR.
* Now fixup the header and scrollbar widths/heights.
*/
vsbR.height = availR.height + vpbInsets.top + vpbInsets.bottom;
hsbR.width = availR.width + vpbInsets.left + vpbInsets.right;
rowHeadR.height = availR.height + vpbInsets.top + vpbInsets.bottom;
rowHeadR.y = availR.y - vpbInsets.top;
colHeadR.width = availR.width + vpbInsets.left + vpbInsets.right;
colHeadR.x = availR.x - vpbInsets.left;
/* Set the bounds of the remaining components. The scrollbars
* are made invisible if they're not needed.
*/
if (rowHead != null) {
rowHead.setBounds(rowHeadR);
}
if (colHead != null) {
colHead.setBounds(colHeadR);
}
if (vsb != null) {
if (vsbNeeded) {
if (colHead != null &&
UIManager.getBoolean("ScrollPane.fillUpperCorner"))
{
if ((leftToRight && upperRight == null) ||
(!leftToRight && upperLeft == null))
{
// This is used primarily for GTK L&F, which needs to
// extend the vertical scrollbar to fill the upper
// corner near the column header. Note that we skip
// this step (and use the default behavior) if the
// user has set a custom corner component.
vsbR.y = colHeadR.y;
vsbR.height += colHeadR.height;
}
}
vsb.setVisible(true);
vsb.setBounds(vsbR);
}
else {
vsb.setVisible(false);
}
}
if (hsb != null) {
if (hsbNeeded) {
if (rowHead != null &&
UIManager.getBoolean("ScrollPane.fillLowerCorner"))
{
if ((leftToRight && lowerLeft == null) ||
(!leftToRight && lowerRight == null))
{
// This is used primarily for GTK L&F, which needs to
// extend the horizontal scrollbar to fill the lower
// corner near the row header. Note that we skip
// this step (and use the default behavior) if the
// user has set a custom corner component.
if (leftToRight) {
hsbR.x = rowHeadR.x;
}
hsbR.width += rowHeadR.width;
}
}
hsb.setVisible(true);
hsb.setBounds(hsbR);
}
else {
hsb.setVisible(false);
}
}
if (lowerLeft != null) {
lowerLeft.setBounds(leftToRight ? rowHeadR.x : vsbR.x,
hsbR.y,
leftToRight ? rowHeadR.width : vsbR.width,
hsbR.height);
}
if (lowerRight != null) {
lowerRight.setBounds(leftToRight ? vsbR.x : rowHeadR.x,
hsbR.y,
leftToRight ? vsbR.width : rowHeadR.width,
hsbR.height);
}
if (upperLeft != null) {
upperLeft.setBounds(leftToRight ? rowHeadR.x : vsbR.x,
colHeadR.y,
leftToRight ? rowHeadR.width : vsbR.width,
colHeadR.height);
}
if (upperRight != null) {
upperRight.setBounds(leftToRight ? vsbR.x : rowHeadR.x,
colHeadR.y,
leftToRight ? vsbR.width : rowHeadR.width,
colHeadR.height);
}
}
Lays out the scrollpane. The positioning of components depends on
the following constraints:
- The row header, if present and visible, gets its preferred
width and the viewport's height.
- The column header, if present and visible, gets its preferred
height and the viewport's width.
- If a vertical scrollbar is needed, i.e. if the viewport's extent
height is smaller than its view height or if the
displayPolicy
is ALWAYS, it's treated like the row header with respect to its
dimensions and is made visible.
- If a horizontal scrollbar is needed, it is treated like the
column header (see the paragraph above regarding the vertical scrollbar).
- If the scrollpane has a non-
null
viewportBorder, then space is allocated for that.
- The viewport gets the space available after accounting for
the previous constraints.
- The corner components, if provided, are aligned with the
ends of the scrollbars and headers. If there is a vertical
scrollbar, the right corners appear; if there is a horizontal
scrollbar, the lower corners appear; a row header gets left
corners, and a column header gets upper corners.
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javax.swing.ScrollPaneLayout
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