Java example source code file (ComponentView.java)
The ComponentView.java Java example source code/*
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*
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* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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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. For Swing components
* this value can be conveniently set using the method
* <code>JComponent.setAlignmentY. For example, setting
* a value of <code>0.75 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.
*/
protected Component createComponent() {
AttributeSet attr = getElement().getAttributes();
Component comp = StyleConstants.getComponent(attr);
return comp;
}
/**
* Fetch 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.
* 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).
*/
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.
* @param b If <code>true, shows this component;
* otherwise, hides this component.
* @see #isVisible
* @since JDK1.1
*/
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;
}
}
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