Java example source code file (LookAndFeel.java)
The LookAndFeel.java Java example source code
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package javax.swing;
import java.awt.Font;
import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;
import java.awt.Color;
import java.awt.Component;
import java.awt.SystemColor;
import java.awt.Toolkit;
import sun.awt.SunToolkit;
import javax.swing.text.*;
import javax.swing.border.*;
import javax.swing.plaf.*;
import java.net.URL;
import sun.swing.SwingUtilities2;
import sun.swing.DefaultLayoutStyle;
import sun.swing.ImageIconUIResource;
import java.util.StringTokenizer;
/**
* {@code LookAndFeel}, as the name implies, encapsulates a look and
* feel. Beyond installing a look and feel most developers never need to
* interact directly with {@code LookAndFeel}. In general only developers
* creating a custom look and feel need to concern themselves with this class.
* <p>
* Swing is built upon the foundation that each {@code JComponent}
* subclass has an implementation of a specific {@code ComponentUI}
* subclass. The {@code ComponentUI} is often referred to as "the ui",
* "component ui", or "look and feel delegate". The {@code ComponentUI}
* subclass is responsible for providing the look and feel specific
* functionality of the component. For example, {@code JTree} requires
* an implementation of the {@code ComponentUI} subclass {@code
* TreeUI}. The implementation of the specific {@code
* ComponentUI} subclass is provided by the {@code LookAndFeel}. Each
* {@code JComponent} subclass identifies the {@code ComponentUI}
* subclass it requires by way of the {@code JComponent} method {@code
* getUIClassID}.
* <p>
* Each {@code LookAndFeel} implementation must provide
* an implementation of the appropriate {@code ComponentUI} subclass by
* specifying a value for each of Swing's ui class ids in the {@code
* UIDefaults} object returned from {@code getDefaults}. For example,
* {@code BasicLookAndFeel} uses {@code BasicTreeUI} as the concrete
* implementation for {@code TreeUI}. This is accomplished by {@code
* BasicLookAndFeel} providing the key-value pair {@code
* "TreeUI"-"javax.swing.plaf.basic.BasicTreeUI"}, in the
* {@code UIDefaults} returned from {@code getDefaults}. Refer to
* {@link UIDefaults#getUI(JComponent)} for details on how the implementation
* of the {@code ComponentUI} subclass is obtained.
* <p>
* When a {@code LookAndFeel} is installed the {@code UIManager} does
* not check that an entry exists for all ui class ids. As such,
* random exceptions will occur if the current look and feel has not
* provided a value for a particular ui class id and an instance of
* the {@code JComponent} subclass is created.
*
* <h2>Recommendations for Look and Feels
*
* As noted in {@code UIManager} each {@code LookAndFeel} has the opportunity
* to provide a set of defaults that are layered in with developer and
* system defaults. Some of Swing's components require the look and feel
* to provide a specific set of defaults. These are documented in the
* classes that require the specific default.
*
* <h3>ComponentUIs and defaults
*
* All {@code ComponentUIs} typically need to set various properties
* on the {@code JComponent} the {@code ComponentUI} is providing the
* look and feel for. This is typically done when the {@code
* ComponentUI} is installed on the {@code JComponent}. Setting a
* property should only be done if the developer has not set the
* property. For non-primitive values it is recommended that the
* {@code ComponentUI} only change the property on the {@code
* JComponent} if the current value is {@code null} or implements
* {@code UIResource}. If the current value is {@code null} or
* implements {@code UIResource} it indicates the property has not
* been set by the developer, and the ui is free to change it. For
* example, {@code BasicButtonUI.installDefaults} only changes the
* font on the {@code JButton} if the return value from {@code
* button.getFont()} is {@code null} or implements {@code
* UIResource}. On the other hand if {@code button.getFont()} returned
* a {@code non-null} value that did not implement {@code UIResource}
* then {@code BasicButtonUI.installDefaults} would not change the
* {@code JButton}'s font.
* <p>
* For primitive values, such as {@code opaque}, the method {@code
* installProperty} should be invoked. {@code installProperty} only changes
* the corresponding property if the value has not been changed by the
* developer.
* <p>
* {@code ComponentUI} implementations should use the various install methods
* provided by this class as they handle the necessary checking and install
* the property using the recommended guidelines.
*
* <h3>Exceptions
*
* All of the install methods provided by {@code LookAndFeel} need to
* access the defaults if the value of the property being changed is
* {@code null} or a {@code UIResource}. For example, installing the
* font does the following:
* <pre>
* JComponent c;
* Font font = c.getFont();
* if (font == null || (font instanceof UIResource)) {
* c.setFont(UIManager.getFont("fontKey"));
* }
* </pre>
* If the font is {@code null} or a {@code UIResource}, the
* defaults table is queried with the key {@code fontKey}. All of
* {@code UIDefault's} get methods throw a {@code
* NullPointerException} if passed in {@code null}. As such, unless
* otherwise noted each of the various install methods of {@code
* LookAndFeel} throw a {@code NullPointerException} if the current
* value is {@code null} or a {@code UIResource} and the supplied
* defaults key is {@code null}. In addition, unless otherwise specified
* all of the {@code install} methods throw a {@code NullPointerException} if
* a {@code null} component is passed in.
*
* @author Tom Ball
* @author Hans Muller
*/
public abstract class LookAndFeel
{
/**
* Convenience method for setting a component's foreground
* and background color properties with values from the
* defaults. The properties are only set if the current
* value is either {@code null} or a {@code UIResource}.
*
* @param c component to set the colors on
* @param defaultBgName key for the background
* @param defaultFgName key for the foreground
*
* @see #installColorsAndFont
* @see UIManager#getColor
* @throws NullPointerException as described in
* <a href="#exceptions">exceptions
*/
public static void installColors(JComponent c,
String defaultBgName,
String defaultFgName)
{
Color bg = c.getBackground();
if (bg == null || bg instanceof UIResource) {
c.setBackground(UIManager.getColor(defaultBgName));
}
Color fg = c.getForeground();
if (fg == null || fg instanceof UIResource) {
c.setForeground(UIManager.getColor(defaultFgName));
}
}
/**
* Convenience method for setting a component's foreground,
* background and font properties with values from the
* defaults. The properties are only set if the current
* value is either {@code null} or a {@code UIResource}.
*
* @param c component set to the colors and font on
* @param defaultBgName key for the background
* @param defaultFgName key for the foreground
* @param defaultFontName key for the font
* @throws NullPointerException as described in
* <a href="#exceptions">exceptions
*
* @see #installColors
* @see UIManager#getColor
* @see UIManager#getFont
*/
public static void installColorsAndFont(JComponent c,
String defaultBgName,
String defaultFgName,
String defaultFontName) {
Font f = c.getFont();
if (f == null || f instanceof UIResource) {
c.setFont(UIManager.getFont(defaultFontName));
}
installColors(c, defaultBgName, defaultFgName);
}
/**
* Convenience method for setting a component's border property with
* a value from the defaults. The border is only set if the border is
* {@code null} or an instance of {@code UIResource}.
*
* @param c component to set the border on
* @param defaultBorderName key specifying the border
* @throws NullPointerException as described in
* <a href="#exceptions">exceptions
*/
public static void installBorder(JComponent c, String defaultBorderName) {
Border b = c.getBorder();
if (b == null || b instanceof UIResource) {
c.setBorder(UIManager.getBorder(defaultBorderName));
}
}
/**
* Convenience method for uninstalling a border. If the border of
* the component is a {@code UIResource}, it is set to {@code
* null}.
*
* @param c component to uninstall the border on
* @throws NullPointerException if {@code c} is {@code null}
*/
public static void uninstallBorder(JComponent c) {
if (c.getBorder() instanceof UIResource) {
c.setBorder(null);
}
}
/**
* Convenience method for installing a property with the specified name
* and value on a component if that property has not already been set
* by the developer. This method is intended to be used by
* ui delegate instances that need to specify a default value for a
* property of primitive type (boolean, int, ..), but do not wish
* to override a value set by the client. Since primitive property
* values cannot be wrapped with the {@code UIResource} marker, this method
* uses private state to determine whether the property has been set
* by the client.
*
* @throws IllegalArgumentException if the specified property is not
* one which can be set using this method
* @throws ClassCastException if the property value has not been set
* by the developer and the type does not match the property's type
* @throws NullPointerException if {@code c} is {@code null}, or the
* named property has not been set by the developer and
* {@code propertyValue} is {@code null}
* @param c target component to set the property on
* @param propertyName name of the property to set
* @param propertyValue value of the property
* @since 1.5
*/
public static void installProperty(JComponent c,
String propertyName, Object propertyValue) {
// this is a special case because the JPasswordField's ancestor hierarchy
// includes a class outside of javax.swing, thus we cannot call setUIProperty
// directly.
if (SunToolkit.isInstanceOf(c, "javax.swing.JPasswordField")) {
if (!((JPasswordField)c).customSetUIProperty(propertyName, propertyValue)) {
c.setUIProperty(propertyName, propertyValue);
}
} else {
c.setUIProperty(propertyName, propertyValue);
}
}
/**
* Convenience method for building an array of {@code
* KeyBindings}. While this method is not deprecated, developers
* should instead use {@code ActionMap} and {@code InputMap} for
* supplying key bindings.
* <p>
* This method returns an array of {@code KeyBindings}, one for each
* alternating {@code key-action} pair in {@code keyBindingList}.
* A {@code key} can either be a {@code String} in the format
* specified by the <code>KeyStroke.getKeyStroke method, or
* a {@code KeyStroke}. The {@code action} part of the pair is a
* {@code String} that corresponds to the name of the {@code
* Action}.
* <p>
* The following example illustrates creating a {@code KeyBinding} array
* from six alternating {@code key-action} pairs:
* <pre>
* JTextComponent.KeyBinding[] multilineBindings = makeKeyBindings( new Object[] {
* "UP", DefaultEditorKit.upAction,
* "DOWN", DefaultEditorKit.downAction,
* "PAGE_UP", DefaultEditorKit.pageUpAction,
* "PAGE_DOWN", DefaultEditorKit.pageDownAction,
* "ENTER", DefaultEditorKit.insertBreakAction,
* "TAB", DefaultEditorKit.insertTabAction
* });
* </pre>
* If {@code keyBindingList's} length is odd, the last element is
* ignored.
* <p>
* Supplying a {@code null} value for either the {@code key} or
* {@code action} part of the {@code key-action} pair results in
* creating a {@code KeyBinding} with the corresponding value
* {@code null}. As other parts of Swing's expect {@code non-null} values
* in a {@code KeyBinding}, you should avoid supplying {@code null} as
* either the {@code key} or {@code action} part of the {@code key-action}
* pair.
*
* @param keyBindingList an array of {@code key-action} pairs
* @return an array of {@code KeyBindings}
* @throws NullPointerException if {@code keyBindingList} is {@code null}
* @throws ClassCastException if the {@code key} part of the pair is
* not a {@code KeyStroke} or {@code String}, or the
* {@code action} part of the pair is not a {@code String}
* @see ActionMap
* @see InputMap
* @see KeyStroke#getKeyStroke
*/
public static JTextComponent.KeyBinding[] makeKeyBindings(Object[] keyBindingList)
{
JTextComponent.KeyBinding[] rv = new JTextComponent.KeyBinding[keyBindingList.length / 2];
for(int i = 0; i < rv.length; i ++) {
Object o = keyBindingList[2 * i];
KeyStroke keystroke = (o instanceof KeyStroke)
? (KeyStroke) o
: KeyStroke.getKeyStroke((String) o);
String action = (String) keyBindingList[2 * i + 1];
rv[i] = new JTextComponent.KeyBinding(keystroke, action);
}
return rv;
}
/**
* Creates a {@code InputMapUIResource} from <code>keys. This is
* a convenience method for creating a new {@code InputMapUIResource},
* invoking {@code loadKeyBindings(map, keys)}, and returning the
* {@code InputMapUIResource}.
*
* @param keys alternating pairs of {@code keystroke-action key}
* pairs as described in {@link #loadKeyBindings}
* @return newly created and populated {@code InputMapUIResource}
* @see #loadKeyBindings
*
* @since 1.3
*/
public static InputMap makeInputMap(Object[] keys) {
InputMap retMap = new InputMapUIResource();
loadKeyBindings(retMap, keys);
return retMap;
}
/**
* Creates a {@code ComponentInputMapUIResource} from
* <code>keys. This is a convenience method for creating a
* new {@code ComponentInputMapUIResource}, invoking {@code
* loadKeyBindings(map, keys)}, and returning the {@code
* ComponentInputMapUIResource}.
*
* @param c component to create the {@code ComponentInputMapUIResource}
* with
* @param keys alternating pairs of {@code keystroke-action key}
* pairs as described in {@link #loadKeyBindings}
* @return newly created and populated {@code InputMapUIResource}
* @throws IllegalArgumentException if {@code c} is {@code null}
*
* @see #loadKeyBindings
* @see ComponentInputMapUIResource
*
* @since 1.3
*/
public static ComponentInputMap makeComponentInputMap(JComponent c,
Object[] keys) {
ComponentInputMap retMap = new ComponentInputMapUIResource(c);
loadKeyBindings(retMap, keys);
return retMap;
}
/**
* Populates an {@code InputMap} with the specified bindings.
* The bindings are supplied as a list of alternating
* {@code keystroke-action key} pairs. The {@code keystroke} is either
* an instance of {@code KeyStroke}, or a {@code String}
* that identifies the {@code KeyStroke} for the binding. Refer
* to {@code KeyStroke.getKeyStroke(String)} for the specific
* format. The {@code action key} part of the pair is the key
* registered in the {@code InputMap} for the {@code KeyStroke}.
* <p>
* The following illustrates loading an {@code InputMap} with two
* {@code key-action} pairs:
* <pre>
* LookAndFeel.loadKeyBindings(inputMap, new Object[] {
* "control X", "cut",
* "control V", "paste"
* });
* </pre>
* <p>
* Supplying a {@code null} list of bindings ({@code keys}) does not
* change {@code retMap} in any way.
* <p>
* Specifying a {@code null} {@code action key} results in
* removing the {@code keystroke's} entry from the {@code InputMap}.
* A {@code null} {@code keystroke} is ignored.
*
* @param retMap {@code InputMap} to add the {@code key-action}
* pairs to
* @param keys bindings to add to {@code retMap}
* @throws NullPointerException if {@code keys} is
* {@code non-null}, not empty, and {@code retMap} is
* {@code null}
*
* @see KeyStroke#getKeyStroke(String)
* @see InputMap
*
* @since 1.3
*/
public static void loadKeyBindings(InputMap retMap, Object[] keys) {
if (keys != null) {
for (int counter = 0, maxCounter = keys.length;
counter < maxCounter; counter++) {
Object keyStrokeO = keys[counter++];
KeyStroke ks = (keyStrokeO instanceof KeyStroke) ?
(KeyStroke)keyStrokeO :
KeyStroke.getKeyStroke((String)keyStrokeO);
retMap.put(ks, keys[counter]);
}
}
}
/**
* Creates and returns a {@code UIDefault.LazyValue} that loads an
* image. The returned value is an implementation of {@code
* UIDefaults.LazyValue}. When {@code createValue} is invoked on
* the returned object, the image is loaded. If the image is {@code
* non-null}, it is then wrapped in an {@code Icon} that implements {@code
* UIResource}. The image is loaded using {@code
* Class.getResourceAsStream(gifFile)}.
* <p>
* This method does not check the arguments in any way. It is
* strongly recommended that {@code non-null} values are supplied else
* exceptions may occur when {@code createValue} is invoked on the
* returned object.
*
* @param baseClass {@code Class} used to load the resource
* @param gifFile path to the image to load
* @return a {@code UIDefaults.LazyValue}; when resolved the
* {@code LazyValue} loads the specified image
* @see UIDefaults.LazyValue
* @see Icon
* @see Class#getResourceAsStream(String)
*/
public static Object makeIcon(final Class<?> baseClass, final String gifFile) {
return SwingUtilities2.makeIcon(baseClass, baseClass, gifFile);
}
/**
* Returns the <code>LayoutStyle for this look
* and feel. This never returns {@code null}.
* <p>
* You generally don't use the <code>LayoutStyle from
* the look and feel, instead use the <code>LayoutStyle
* method <code>getInstance.
*
* @see LayoutStyle#getInstance
* @return the <code>LayoutStyle for this look and feel
* @since 1.6
*/
public LayoutStyle getLayoutStyle() {
return DefaultLayoutStyle.getInstance();
}
/**
* Invoked when the user attempts an invalid operation,
* such as pasting into an uneditable <code>JTextField
* that has focus. The default implementation beeps. Subclasses
* that wish different behavior should override this and provide
* the additional feedback.
*
* @param component the <code>Component the error occurred in,
* may be <code>null
* indicating the error condition is not directly
* associated with a <code>Component
* @since 1.4
*/
public void provideErrorFeedback(Component component) {
Toolkit toolkit = null;
if (component != null) {
toolkit = component.getToolkit();
} else {
toolkit = Toolkit.getDefaultToolkit();
}
toolkit.beep();
} // provideErrorFeedback()
/**
* Returns the value of the specified system desktop property by
* invoking <code>Toolkit.getDefaultToolkit().getDesktopProperty().
* If the value of the specified property is {@code null},
* {@code fallbackValue} is returned.
*
* @param systemPropertyName the name of the system desktop property being queried
* @param fallbackValue the object to be returned as the value if the system value is null
* @return the current value of the desktop property
*
* @see java.awt.Toolkit#getDesktopProperty
*
* @since 1.4
*/
public static Object getDesktopPropertyValue(String systemPropertyName, Object fallbackValue) {
Object value = Toolkit.getDefaultToolkit().getDesktopProperty(systemPropertyName);
if (value == null) {
return fallbackValue;
} else if (value instanceof Color) {
return new ColorUIResource((Color)value);
} else if (value instanceof Font) {
return new FontUIResource((Font)value);
}
return value;
}
/**
* Returns an <code>Icon with a disabled appearance.
* This method is used to generate a disabled <code>Icon when
* one has not been specified. For example, if you create a
* <code>JButton and only specify an
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