basicscrollpaneui.java

Mobile 应用程序使用 Java Micro Edition (Java ME) 平台

                            int direction, boolean block) {
	    JViewport vp = scrollpane.getViewport();
	    Component view;
	    if (vp != null && (view = vp.getView()) != null) {
		Rectangle visRect = vp.getViewRect();
		Dimension vSize = view.getSize();
		int amount;

		if (view instanceof Scrollable) {
		    if (block) {
			amount = ((Scrollable)view).getScrollableBlockIncrement
			         (visRect, orientation, direction);
		    }
		    else {
			amount = ((Scrollable)view).getScrollableUnitIncrement
			         (visRect, orientation, direction);
		    }
		}
		else {
		    if (block) {
			if (orientation == SwingConstants.VERTICAL) {
			    amount = visRect.height;
			}
			else {
			    amount = visRect.width;
			}
		    }
		    else {
			amount = 10;
		    }
		}
		if (orientation == SwingConstants.VERTICAL) {
		    visRect.y += (amount * direction);
		    if ((visRect.y + visRect.height) > vSize.height) {
			visRect.y = Math.max(0, vSize.height - visRect.height);
		    }
		    else if (visRect.y < 0) {
			visRect.y = 0;
		    }
		}
		else {
		    if (scrollpane.getComponentOrientation().isLeftToRight()) {
			visRect.x += (amount * direction);
			if ((visRect.x + visRect.width) > vSize.width) {
			    visRect.x = Math.max(0, vSize.width - visRect.width);
			} else if (visRect.x < 0) {
			    visRect.x = 0;
			}
		    } else {
			visRect.x -= (amount * direction);
                        if (visRect.width > vSize.width) {
                            visRect.x = vSize.width - visRect.width;
                        } else {
                            visRect.x = Math.max(0, Math.min(vSize.width - visRect.width, visRect.x));
			}
		    }
		}
		vp.setViewPosition(visRect.getLocation());
	    }
	}
    }


    class Handler implements ChangeListener, PropertyChangeListener, MouseWheelListener {
        //
        // MouseWheelListener
        //
        public void mouseWheelMoved(MouseWheelEvent e) {
            if (scrollpane.isWheelScrollingEnabled() &&
                e.getWheelRotation() != 0) {
                JScrollBar toScroll = scrollpane.getVerticalScrollBar();
                int direction = e.getWheelRotation() < 0 ? -1 : 1;
                int orientation = SwingConstants.VERTICAL;

                // find which scrollbar to scroll, or return if none
                if (toScroll == null || !toScroll.isVisible()) { 
                    toScroll = scrollpane.getHorizontalScrollBar();
                    if (toScroll == null || !toScroll.isVisible()) { 
                        return;
                    }
                    orientation = SwingConstants.HORIZONTAL;
                }

                if (e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) {
                    JViewport vp = scrollpane.getViewport();
                    if (vp == null) { return; }
                    Component comp = vp.getView();
                    int units = Math.abs(e.getUnitsToScroll());

                    // When the scrolling speed is set to maximum, it's possible
                    // for a single wheel click to scroll by more units than
                    // will fit in the visible area.  This makes it
                    // hard/impossible to get to certain parts of the scrolling
                    // Component with the wheel.  To make for more accurate
                    // low-speed scrolling, we limit scrolling to the block
                    // increment if the wheel was only rotated one click.
                    boolean limitScroll = Math.abs(e.getWheelRotation()) == 1;

                    // Check if we should use the visibleRect trick
                    Object fastWheelScroll = toScroll.getClientProperty(
                                               "JScrollBar.fastWheelScrolling");
                    if (Boolean.TRUE == fastWheelScroll &&
                        comp instanceof Scrollable) {
                        // 5078454: Under maximum acceleration, we may scroll
                        // by many 100s of units in ~1 second.
                        //
                        // BasicScrollBarUI.scrollByUnits() can bog down the EDT
                        // with repaints in this situation.  However, the
                        // Scrollable interface allows us to pass in an
                        // arbitrary visibleRect.  This allows us to accurately
                        // calculate the total scroll amount, and then update
                        // the GUI once.  This technique provides much faster
                        // accelerated wheel scrolling.
                        Scrollable scrollComp = (Scrollable) comp;
                        Rectangle viewRect = vp.getViewRect();
                        int startingX = viewRect.x;
                        boolean leftToRight =
                                 comp.getComponentOrientation().isLeftToRight();
                        int scrollMin = toScroll.getMinimum();
                        int scrollMax = toScroll.getMaximum() -
                                        toScroll.getModel().getExtent();

                        if (limitScroll) {
                            int blockIncr =
                                scrollComp.getScrollableBlockIncrement(viewRect,
                                                                    orientation,
                                                                    direction);
                            if (direction < 0) {
                                scrollMin = Math.max(scrollMin,
                                               toScroll.getValue() - blockIncr);
                            }
                            else {
                                scrollMax = Math.min(scrollMax,
                                               toScroll.getValue() + blockIncr);
                            }
                        }

                        for (int i = 0; i < units; i++) {
                            int unitIncr =
                                scrollComp.getScrollableUnitIncrement(viewRect,
                                                        orientation, direction);
                            // Modify the visible rect for the next unit, and
                            // check to see if we're at the end already.
                            if (orientation == SwingConstants.VERTICAL) {
                                if (direction < 0) {
                                    viewRect.y -= unitIncr;
                                    if (viewRect.y <= scrollMin) {
                                        viewRect.y = scrollMin;
                                        break;
                                    }
                                }
                                else { // (direction > 0
                                    viewRect.y += unitIncr;
                                    if (viewRect.y >= scrollMax) {
                                        viewRect.y = scrollMax;
                                        break;
                                    }
                                }
                            }
                            else {
                                // Scroll left
                                if ((leftToRight && direction < 0) ||
                                    (!leftToRight && direction > 0)) {
                                    viewRect.x -= unitIncr;
                                    if (leftToRight) {
                                        if (viewRect.x < scrollMin) {
                                            viewRect.x = scrollMin;
                                            break;
                                        }
                                    }
                                }
                                // Scroll right
                                else if ((leftToRight && direction > 0) ||
                                    (!leftToRight && direction < 0)) {
                                    viewRect.x += unitIncr;
                                    if (leftToRight) {
                                        if (viewRect.x > scrollMax) {
                                            viewRect.x = scrollMax;
                                            break;
                                        }
                                    }
                                }
                                else {
                                    assert false : "Non-sensical ComponentOrientation / scroll direction";
                                }
                            }
                        }
                        // Set the final view position on the ScrollBar
                        if (orientation == SwingConstants.VERTICAL) {
                            toScroll.setValue(viewRect.y);
                        }
                        else {
                            if (leftToRight) {
                                toScroll.setValue(viewRect.x);
                            }
                            else {
                                // rightToLeft scrollbars are oriented with 
                                // minValue on the right and maxValue on the
                                // left.
                                int newPos = toScroll.getValue() -
                                                       (viewRect.x - startingX);
                                if (newPos < scrollMin) {
                                    newPos = scrollMin;
                                }
                                else if (newPos > scrollMax) {
                                    newPos = scrollMax;
                                }
                                toScroll.setValue(newPos);
                            }
                        }
                    }
                    else {
                        // Viewport's view is not a Scrollable, or fast wheel
                        // scrolling is not enabled.
                        BasicScrollBarUI.scrollByUnits(toScroll, direction,
                                                       units, limitScroll);
                    }
                }
                else if (e.getScrollType() ==
                         MouseWheelEvent.WHEEL_BLOCK_SCROLL) {
                    BasicScrollBarUI.scrollByBlock(toScroll, direction);
                }
            }
        }

        //
        // ChangeListener: This is added to the vieport, and hsb/vsb models.
        //
	public void stateChanged(ChangeEvent e) {
            JViewport viewport = scrollpane.getViewport();

            if (viewport != null) {
                if (e.getSource() == viewport) {
                    viewportStateChanged(e);
                }
                else {
                    JScrollBar hsb = scrollpane.getHorizontalScrollBar();
                    if (hsb != null && e.getSource() == hsb.getModel()) {
                        hsbStateChanged(viewport, e);
                    }
                    else {
                        JScrollBar vsb = scrollpane.getVerticalScrollBar();
                        if (vsb != null && e.getSource() == vsb.getModel()) {
                            vsbStateChanged(viewport, e);
                        }
                    }
                }
            }
        }

        private void vsbStateChanged(JViewport viewport, ChangeEvent e) {
            BoundedRangeModel model = (BoundedRangeModel)(e.getSource());
            Point p = viewport.getViewPosition();
            p.y = model.getValue();
            viewport.setViewPosition(p);
        }

        private void hsbStateChanged(JViewport viewport, ChangeEvent e) {
            BoundedRangeModel model = (BoundedRangeModel)(e.getSource());
            Point p = viewport.getViewPosition();
            int value = model.getValue();
            if (scrollpane.getComponentOrientation().isLeftToRight()) {
                p.x = value;
            } else {
                int max = viewport.getViewSize().width;
                int extent = viewport.getExtentSize().width;
                int oldX = p.x;

                /* Set new X coordinate based on "value".
                 */
                p.x = max - extent - value;

                /* If setValue() was called before "extent" was fixed,
                 * turn setValueCalled flag on.
                 */
                if ((extent == 0) && (value != 0) && (oldX == max)) {
                    setValueCalled = true;
                } else {
                    /* When a pane without a horizontal scroll bar was
                     * reduced and the bar appeared, the viewport should
                     * show the right side of the view.
                     */
                    if ((extent != 0) && (oldX < 0) && (p.x == 0)) {
                        p.x += value;
                    }
                }
            }
            viewport.setViewPosition(p);
        }

        private void viewportStateChanged(ChangeEvent e) {
            syncScrollPaneWithViewport();
	}


        //
        // PropertyChangeListener: This is installed on both the JScrollPane
        // and the horizontal/vertical scrollbars.
        //

        // Listens for changes in the model property and reinstalls the
        // horizontal/vertical PropertyChangeListeners.
        public void propertyChange(PropertyChangeEvent e) {
            if (e.getSource() == scrollpane) {
                scrollPanePropertyChange(e);
            }
            else {
                sbPropertyChange(e);
            }
        }

        private void scrollPanePropertyChange(PropertyChangeEvent e) {
            String propertyName = e.getPropertyName();

	    if (propertyName == "verticalScrollBarDisplayPolicy") {
		updateScrollBarDisplayPolicy(e);
	    }
	    else if (propertyName == "horizontalScrollBarDisplayPolicy") {
		updateScrollBarDisplayPolicy(e);
	    }
	    else if (propertyName == "viewport") {
		updateViewport(e);
	    }
	    else if (propertyName == "rowHeader") {
		updateRowHeader(e);
	    }
	    else if (propertyName == "columnHeader") {
		updateColumnHeader(e);
	    }
	    else if (propertyName == "verticalScrollBar") {
		updateVerticalScrollBar(e);
	    }
	    else if (propertyName == "horizontalScrollBar") {
		updateHorizontalScrollBar(e);
	    }
	    else if (propertyName == "componentOrientation") {
		scrollpane.revalidate();
		scrollpane.repaint();
	    }
        }

        // PropertyChangeListener for the horizontal and vertical scrollbars.
        private void sbPropertyChange(PropertyChangeEvent e) {
            String propertyName = e.getPropertyName();
            Object source = e.getSource();

            if ("model" == propertyName) {
                JScrollBar sb = scrollpane.getVerticalScrollBar();
                BoundedRangeModel oldModel = (BoundedRangeModel)e.
                                     getOldValue();
                ChangeListener cl = null;

                if (source == sb) {
                    cl = vsbChangeListener;
                }
                else if (source == scrollpane.getHorizontalScrollBar()) {
                    sb = scrollpane.getHorizontalScrollBar();
                    cl = hsbChangeListener;
                }
                if (cl != null) {
                    if (oldModel != null) {
                        oldModel.removeChangeListener(cl);
                    }
                    if (sb.getModel() != null) {
                        sb.getModel().addChangeListener(cl);
                    }
                }
            }
            else if ("componentOrientation" == propertyName) {
                if (source == scrollpane.getHorizontalScrollBar()) {
		    JScrollBar hsb = scrollpane.getHorizontalScrollBar();
 		    JViewport viewport = scrollpane.getViewport();
                    Point p = viewport.getViewPosition();
                    if (scrollpane.getComponentOrientation().isLeftToRight()) {
                        p.x = hsb.getValue();
                    } else {
                        p.x = viewport.getViewSize().width - viewport.getExtentSize().width - hsb.getValue();
                    }
                    viewport.setViewPosition(p);
                }
            }
        }
    }
}