Java tutorial
/* * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.swing.text; import java.awt.*; import java.beans.PropertyChangeEvent; import java.beans.PropertyChangeListener; import java.util.Set; import javax.swing.SwingUtilities; import javax.swing.event.*; /** * Component decorator that implements the view interface. The * entire element is used to represent the component. This acts * as a gateway from the display-only View implementations to * interactive lightweight components (ie it allows components * to be embedded into the View hierarchy). * <p> * The component is placed relative to the text baseline * according to the value returned by * <code>Component.getAlignmentY</code>. For Swing components * this value can be conveniently set using the method * <code>JComponent.setAlignmentY</code>. For example, setting * a value of <code>0.75</code> will cause 75 percent of the * component to be above the baseline, and 25 percent of the * component to be below the baseline. * <p> * This class is implemented to do the extra work necessary to * work properly in the presence of multiple threads (i.e. from * asynchronous notification of model changes for example) by * ensuring that all component access is done on the event thread. * <p> * The component used is determined by the return value of the * createComponent method. The default implementation of this * method is to return the component held as an attribute of * the element (by calling StyleConstants.getComponent). A * limitation of this behavior is that the component cannot * be used by more than one text component (i.e. with a shared * model). Subclasses can remove this constraint by implementing * the createComponent to actually create a component based upon * some kind of specification contained in the attributes. The * ObjectView class in the html package is an example of a * ComponentView implementation that supports multiple component * views of a shared model. * * @author Timothy Prinzing */ public class ComponentView extends View { /** * Creates a new ComponentView object. * * @param elem the element to decorate */ public ComponentView(Element elem) { super(elem); } /** * Create the component that is associated with * this view. This will be called when it has * been determined that a new component is needed. * This would result from a call to setParent or * as a result of being notified that attributes * have changed. * @return the component that is associated with * this view */ protected Component createComponent() { AttributeSet attr = getElement().getAttributes(); Component comp = StyleConstants.getComponent(attr); return comp; } /** * Fetch the component associated with the view. * @return the component associated with the view */ public final Component getComponent() { return createdC; } // --- View methods --------------------------------------------- /** * The real paint behavior occurs naturally from the association * that the component has with its parent container (the same * container hosting this view). This is implemented to do nothing. * * @param g the graphics context * @param a the shape * @see View#paint */ public void paint(Graphics g, Shape a) { if (c != null) { Rectangle alloc = (a instanceof Rectangle) ? (Rectangle) a : a.getBounds(); c.setBounds(alloc.x, alloc.y, alloc.width, alloc.height); } } /** * Determines the preferred span for this view along an * axis. This is implemented to return the value * returned by Component.getPreferredSize along the * axis of interest. * * @param axis may be either View.X_AXIS or View.Y_AXIS * @return the span the view would like to be rendered into >=0. * Typically the view is told to render into the span * that is returned, although there is no guarantee. * The parent may choose to resize or break the view. * @exception IllegalArgumentException for an invalid axis */ public float getPreferredSpan(int axis) { if ((axis != X_AXIS) && (axis != Y_AXIS)) { throw new IllegalArgumentException("Invalid axis: " + axis); } if (c != null) { Dimension size = c.getPreferredSize(); if (axis == View.X_AXIS) { return size.width; } else { return size.height; } } return 0; } /** * Determines the minimum span for this view along an * axis. This is implemented to return the value * returned by Component.getMinimumSize along the * axis of interest. * * @param axis may be either View.X_AXIS or View.Y_AXIS * @return the span the view would like to be rendered into >=0. * Typically the view is told to render into the span * that is returned, although there is no guarantee. * The parent may choose to resize or break the view. * @exception IllegalArgumentException for an invalid axis */ public float getMinimumSpan(int axis) { if ((axis != X_AXIS) && (axis != Y_AXIS)) { throw new IllegalArgumentException("Invalid axis: " + axis); } if (c != null) { Dimension size = c.getMinimumSize(); if (axis == View.X_AXIS) { return size.width; } else { return size.height; } } return 0; } /** * Determines the maximum span for this view along an * axis. This is implemented to return the value * returned by Component.getMaximumSize along the * axis of interest. * * @param axis may be either View.X_AXIS or View.Y_AXIS * @return the span the view would like to be rendered into >=0. * Typically the view is told to render into the span * that is returned, although there is no guarantee. * The parent may choose to resize or break the view. * @exception IllegalArgumentException for an invalid axis */ public float getMaximumSpan(int axis) { if ((axis != X_AXIS) && (axis != Y_AXIS)) { throw new IllegalArgumentException("Invalid axis: " + axis); } if (c != null) { Dimension size = c.getMaximumSize(); if (axis == View.X_AXIS) { return size.width; } else { return size.height; } } return 0; } /** * Determines the desired alignment for this view along an * axis. This is implemented to give the alignment of the * embedded component. * * @param axis may be either View.X_AXIS or View.Y_AXIS * @return the desired alignment. This should be a value * between 0.0 and 1.0 where 0 indicates alignment at the * origin and 1.0 indicates alignment to the full span * away from the origin. An alignment of 0.5 would be the * center of the view. */ public float getAlignment(int axis) { if (c != null) { switch (axis) { case View.X_AXIS: return c.getAlignmentX(); case View.Y_AXIS: return c.getAlignmentY(); } } return super.getAlignment(axis); } /** * Sets the parent for a child view. * The parent calls this on the child to tell it who its * parent is, giving the view access to things like * the hosting Container. The superclass behavior is * executed, followed by a call to createComponent if * the parent view parameter is non-null and a component * has not yet been created. The embedded components parent * is then set to the value returned by <code>getContainer</code>. * If the parent view parameter is null, this view is being * cleaned up, thus the component is removed from its parent. * <p> * The changing of the component hierarchy will * touch the component lock, which is the one thing * that is not safe from the View hierarchy. Therefore, * this functionality is executed immediately if on the * event thread, or is queued on the event queue if * called from another thread (notification of change * from an asynchronous update). * * @param p the parent */ public void setParent(View p) { super.setParent(p); if (SwingUtilities.isEventDispatchThread()) { setComponentParent(); } else { Runnable callSetComponentParent = new Runnable() { public void run() { Document doc = getDocument(); try { if (doc instanceof AbstractDocument) { ((AbstractDocument) doc).readLock(); } setComponentParent(); Container host = getContainer(); if (host != null) { preferenceChanged(null, true, true); host.repaint(); } } finally { if (doc instanceof AbstractDocument) { ((AbstractDocument) doc).readUnlock(); } } } }; SwingUtilities.invokeLater(callSetComponentParent); } } /** * Set the parent of the embedded component * with assurance that it is thread-safe. */ void setComponentParent() { View p = getParent(); if (p != null) { Container parent = getContainer(); if (parent != null) { if (c == null) { // try to build a component Component comp = createComponent(); if (comp != null) { createdC = comp; c = new Invalidator(comp); } } if (c != null) { if (c.getParent() == null) { // components associated with the View tree are added // to the hosting container with the View as a constraint. parent.add(c, this); parent.addPropertyChangeListener("enabled", c); } } } } else { if (c != null) { Container parent = c.getParent(); if (parent != null) { // remove the component from its hosting container parent.remove(c); parent.removePropertyChangeListener("enabled", c); } } } } /** * Provides a mapping from the coordinate space of the model to * that of the view. * * @param pos the position to convert >=0 * @param a the allocated region to render into * @return the bounding box of the given position is returned * @exception BadLocationException if the given position does not * represent a valid location in the associated document * @see View#modelToView */ public Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException { int p0 = getStartOffset(); int p1 = getEndOffset(); if ((pos >= p0) && (pos <= p1)) { Rectangle r = a.getBounds(); if (pos == p1) { r.x += r.width; } r.width = 0; return r; } throw new BadLocationException(pos + " not in range " + p0 + "," + p1, pos); } /** * Provides a mapping from the view coordinate space to the logical * coordinate space of the model. * * @param x the X coordinate >=0 * @param y the Y coordinate >=0 * @param a the allocated region to render into * @return the location within the model that best represents * the given point in the view * @see View#viewToModel */ public int viewToModel(float x, float y, Shape a, Position.Bias[] bias) { Rectangle alloc = (Rectangle) a; if (x < alloc.x + (alloc.width / 2)) { bias[0] = Position.Bias.Forward; return getStartOffset(); } bias[0] = Position.Bias.Backward; return getEndOffset(); } // --- member variables ------------------------------------------------ private Component createdC; private Invalidator c; /** * This class feeds the invalidate back to the * hosting View. This is needed to get the View * hierarchy to consider giving the component * a different size (i.e. layout may have been * cached between the associated view and the * container hosting this component). */ @SuppressWarnings("serial") // JDK-implementation class class Invalidator extends Container implements PropertyChangeListener { // NOTE: When we remove this class we are going to have to some // how enforce setting of the focus traversal keys on the children // so that they don't inherit them from the JEditorPane. We need // to do this as JEditorPane has abnormal bindings (it is a focus cycle // root) and the children typically don't want these bindings as well. Invalidator(Component child) { setLayout(null); add(child); cacheChildSizes(); } /** * The components invalid layout needs * to be propagated through the view hierarchy * so the views (which position the component) * can have their layout recomputed. */ public void invalidate() { super.invalidate(); if (getParent() != null) { preferenceChanged(null, true, true); } } public void doLayout() { cacheChildSizes(); } public void setBounds(int x, int y, int w, int h) { super.setBounds(x, y, w, h); if (getComponentCount() > 0) { getComponent(0).setSize(w, h); } cacheChildSizes(); } public void validateIfNecessary() { if (!isValid()) { validate(); } } private void cacheChildSizes() { if (getComponentCount() > 0) { Component child = getComponent(0); min = child.getMinimumSize(); pref = child.getPreferredSize(); max = child.getMaximumSize(); yalign = child.getAlignmentY(); xalign = child.getAlignmentX(); } else { min = pref = max = new Dimension(0, 0); } } /** * Shows or hides this component depending on the value of parameter * <code>b</code>. * @param b If <code>true</code>, shows this component; * otherwise, hides this component. * @see #isVisible * @since 1.1 */ public void setVisible(boolean b) { super.setVisible(b); if (getComponentCount() > 0) { getComponent(0).setVisible(b); } } /** * Overridden to fix 4759054. Must return true so that content * is painted when inside a CellRendererPane which is normally * invisible. */ public boolean isShowing() { return true; } public Dimension getMinimumSize() { validateIfNecessary(); return min; } public Dimension getPreferredSize() { validateIfNecessary(); return pref; } public Dimension getMaximumSize() { validateIfNecessary(); return max; } public float getAlignmentX() { validateIfNecessary(); return xalign; } public float getAlignmentY() { validateIfNecessary(); return yalign; } public Set<AWTKeyStroke> getFocusTraversalKeys(int id) { return KeyboardFocusManager.getCurrentKeyboardFocusManager().getDefaultFocusTraversalKeys(id); } public void propertyChange(PropertyChangeEvent ev) { Boolean enable = (Boolean) ev.getNewValue(); if (getComponentCount() > 0) { getComponent(0).setEnabled(enable); } } Dimension min; Dimension pref; Dimension max; float yalign; float xalign; } }