Java example source code file (BasicHTML.java)
The BasicHTML.java Java example source code/*
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* 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,
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*
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package javax.swing.plaf.basic;
import java.io.*;
import java.awt.*;
import java.net.URL;
import javax.swing.*;
import javax.swing.text.*;
import javax.swing.text.html.*;
import sun.swing.SwingUtilities2;
/**
* Support for providing html views for the swing components.
* This translates a simple html string to a javax.swing.text.View
* implementation that can render the html and provide the necessary
* layout semantics.
*
* @author Timothy Prinzing
* @since 1.3
*/
public class BasicHTML {
/**
* Create an html renderer for the given component and
* string of html.
*/
public static View createHTMLView(JComponent c, String html) {
BasicEditorKit kit = getFactory();
Document doc = kit.createDefaultDocument(c.getFont(),
c.getForeground());
Object base = c.getClientProperty(documentBaseKey);
if (base instanceof URL) {
((HTMLDocument)doc).setBase((URL)base);
}
Reader r = new StringReader(html);
try {
kit.read(r, doc, 0);
} catch (Throwable e) {
}
ViewFactory f = kit.getViewFactory();
View hview = f.create(doc.getDefaultRootElement());
View v = new Renderer(c, f, hview);
return v;
}
/**
* Returns the baseline for the html renderer.
*
* @param view the View to get the baseline for
* @param w the width to get the baseline for
* @param h the height to get the baseline for
* @throws IllegalArgumentException if width or height is < 0
* @return baseline or a value < 0 indicating there is no reasonable
* baseline
* @see java.awt.FontMetrics
* @see javax.swing.JComponent#getBaseline(int,int)
* @since 1.6
*/
public static int getHTMLBaseline(View view, int w, int h) {
if (w < 0 || h < 0) {
throw new IllegalArgumentException(
"Width and height must be >= 0");
}
if (view instanceof Renderer) {
return getBaseline(view.getView(0), w, h);
}
return -1;
}
/**
* Gets the baseline for the specified component. This digs out
* the View client property, and if non-null the baseline is calculated
* from it. Otherwise the baseline is the value <code>y + ascent.
*/
static int getBaseline(JComponent c, int y, int ascent,
int w, int h) {
View view = (View)c.getClientProperty(BasicHTML.propertyKey);
if (view != null) {
int baseline = getHTMLBaseline(view, w, h);
if (baseline < 0) {
return baseline;
}
return y + baseline;
}
return y + ascent;
}
/**
* Gets the baseline for the specified View.
*/
static int getBaseline(View view, int w, int h) {
if (hasParagraph(view)) {
view.setSize(w, h);
return getBaseline(view, new Rectangle(0, 0, w, h));
}
return -1;
}
private static int getBaseline(View view, Shape bounds) {
if (view.getViewCount() == 0) {
return -1;
}
AttributeSet attributes = view.getElement().getAttributes();
Object name = null;
if (attributes != null) {
name = attributes.getAttribute(StyleConstants.NameAttribute);
}
int index = 0;
if (name == HTML.Tag.HTML && view.getViewCount() > 1) {
// For html on widgets the header is not visible, skip it.
index++;
}
bounds = view.getChildAllocation(index, bounds);
if (bounds == null) {
return -1;
}
View child = view.getView(index);
if (view instanceof javax.swing.text.ParagraphView) {
Rectangle rect;
if (bounds instanceof Rectangle) {
rect = (Rectangle)bounds;
}
else {
rect = bounds.getBounds();
}
return rect.y + (int)(rect.height *
child.getAlignment(View.Y_AXIS));
}
return getBaseline(child, bounds);
}
private static boolean hasParagraph(View view) {
if (view instanceof javax.swing.text.ParagraphView) {
return true;
}
if (view.getViewCount() == 0) {
return false;
}
AttributeSet attributes = view.getElement().getAttributes();
Object name = null;
if (attributes != null) {
name = attributes.getAttribute(StyleConstants.NameAttribute);
}
int index = 0;
if (name == HTML.Tag.HTML && view.getViewCount() > 1) {
// For html on widgets the header is not visible, skip it.
index = 1;
}
return hasParagraph(view.getView(index));
}
/**
* Check the given string to see if it should trigger the
* html rendering logic in a non-text component that supports
* html rendering.
*/
public static boolean isHTMLString(String s) {
if (s != null) {
if ((s.length() >= 6) && (s.charAt(0) == '<') && (s.charAt(5) == '>')) {
String tag = s.substring(1,5);
return tag.equalsIgnoreCase(propertyKey);
}
}
return false;
}
/**
* Stash the HTML render for the given text into the client
* properties of the given JComponent. If the given text is
* <em>NOT HTML the property will be cleared of any
* renderer.
* <p>
* This method is useful for ComponentUI implementations
* that are static (i.e. shared) and get their state
* entirely from the JComponent.
*/
public static void updateRenderer(JComponent c, String text) {
View value = null;
View oldValue = (View)c.getClientProperty(BasicHTML.propertyKey);
Boolean htmlDisabled = (Boolean) c.getClientProperty(htmlDisable);
if (htmlDisabled != Boolean.TRUE && BasicHTML.isHTMLString(text)) {
value = BasicHTML.createHTMLView(c, text);
}
if (value != oldValue && oldValue != null) {
for (int i = 0; i < oldValue.getViewCount(); i++) {
oldValue.getView(i).setParent(null);
}
}
c.putClientProperty(BasicHTML.propertyKey, value);
}
/**
* If this client property of a JComponent is set to Boolean.TRUE
* the component's 'text' property is never treated as HTML.
*/
private static final String htmlDisable = "html.disable";
/**
* Key to use for the html renderer when stored as a
* client property of a JComponent.
*/
public static final String propertyKey = "html";
/**
* Key stored as a client property to indicate the base that relative
* references are resolved against. For example, lets say you keep
* your images in the directory resources relative to the code path,
* you would use the following the set the base:
* <pre>
* jComponent.putClientProperty(documentBaseKey,
* xxx.class.getResource("resources/"));
* </pre>
*/
public static final String documentBaseKey = "html.base";
static BasicEditorKit getFactory() {
if (basicHTMLFactory == null) {
basicHTMLViewFactory = new BasicHTMLViewFactory();
basicHTMLFactory = new BasicEditorKit();
}
return basicHTMLFactory;
}
/**
* The source of the html renderers
*/
private static BasicEditorKit basicHTMLFactory;
/**
* Creates the Views that visually represent the model.
*/
private static ViewFactory basicHTMLViewFactory;
/**
* Overrides to the default stylesheet. Should consider
* just creating a completely fresh stylesheet.
*/
private static final String styleChanges =
"p { margin-top: 0; margin-bottom: 0; margin-left: 0; margin-right: 0 }" +
"body { margin-top: 0; margin-bottom: 0; margin-left: 0; margin-right: 0 }";
/**
* The views produced for the ComponentUI implementations aren't
* going to be edited and don't need full html support. This kit
* alters the HTMLEditorKit to try and trim things down a bit.
* It does the following:
* <ul>
* <li>It doesn't produce Views for things like comments,
* head, title, unknown tags, etc.
* <li>It installs a different set of css settings from the default
* provided by HTMLEditorKit.
* </ul>
*/
static class BasicEditorKit extends HTMLEditorKit {
/** Shared base style for all documents created by us use. */
private static StyleSheet defaultStyles;
/**
* Overriden to return our own slimmed down style sheet.
*/
public StyleSheet getStyleSheet() {
if (defaultStyles == null) {
defaultStyles = new StyleSheet();
StringReader r = new StringReader(styleChanges);
try {
defaultStyles.loadRules(r, null);
} catch (Throwable e) {
// don't want to die in static initialization...
// just display things wrong.
}
r.close();
defaultStyles.addStyleSheet(super.getStyleSheet());
}
return defaultStyles;
}
/**
* Sets the async policy to flush everything in one chunk, and
* to not display unknown tags.
*/
public Document createDefaultDocument(Font defaultFont,
Color foreground) {
StyleSheet styles = getStyleSheet();
StyleSheet ss = new StyleSheet();
ss.addStyleSheet(styles);
BasicDocument doc = new BasicDocument(ss, defaultFont, foreground);
doc.setAsynchronousLoadPriority(Integer.MAX_VALUE);
doc.setPreservesUnknownTags(false);
return doc;
}
/**
* Returns the ViewFactory that is used to make sure the Views don't
* load in the background.
*/
public ViewFactory getViewFactory() {
return basicHTMLViewFactory;
}
}
/**
* BasicHTMLViewFactory extends HTMLFactory to force images to be loaded
* synchronously.
*/
static class BasicHTMLViewFactory extends HTMLEditorKit.HTMLFactory {
public View create(Element elem) {
View view = super.create(elem);
if (view instanceof ImageView) {
((ImageView)view).setLoadsSynchronously(true);
}
return view;
}
}
/**
* The subclass of HTMLDocument that is used as the model. getForeground
* is overridden to return the foreground property from the Component this
* was created for.
*/
static class BasicDocument extends HTMLDocument {
/** The host, that is where we are rendering. */
// private JComponent host;
BasicDocument(StyleSheet s, Font defaultFont, Color foreground) {
super(s);
setPreservesUnknownTags(false);
setFontAndColor(defaultFont, foreground);
}
/**
* Sets the default font and default color. These are set by
* adding a rule for the body that specifies the font and color.
* This allows the html to override these should it wish to have
* a custom font or color.
*/
private void setFontAndColor(Font font, Color fg) {
getStyleSheet().addRule(sun.swing.SwingUtilities2.
displayPropertiesToCSS(font,fg));
}
}
/**
* Root text view that acts as an HTML renderer.
*/
static class Renderer extends View {
Renderer(JComponent c, ViewFactory f, View v) {
super(null);
host = c;
factory = f;
view = v;
view.setParent(this);
// initially layout to the preferred size
setSize(view.getPreferredSpan(X_AXIS), view.getPreferredSpan(Y_AXIS));
}
/**
* Fetches the attributes to use when rendering. At the root
* level there are no attributes. If an attribute is resolved
* up the view hierarchy this is the end of the line.
*/
public AttributeSet getAttributes() {
return null;
}
/**
* Determines the preferred span for this view along an axis.
*
* @param axis may be either X_AXIS or Y_AXIS
* @return the span the view would like to be rendered into.
* 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.
*/
public float getPreferredSpan(int axis) {
if (axis == X_AXIS) {
// width currently laid out to
return width;
}
return view.getPreferredSpan(axis);
}
/**
* Determines the minimum span for this view along an axis.
*
* @param axis may be either X_AXIS or Y_AXIS
* @return the span the view would like to be rendered into.
* 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.
*/
public float getMinimumSpan(int axis) {
return view.getMinimumSpan(axis);
}
/**
* Determines the maximum span for this view along an axis.
*
* @param axis may be either X_AXIS or Y_AXIS
* @return the span the view would like to be rendered into.
* 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.
*/
public float getMaximumSpan(int axis) {
return Integer.MAX_VALUE;
}
/**
* Specifies that a preference has changed.
* Child views can call this on the parent to indicate that
* the preference has changed. The root view routes this to
* invalidate on the hosting component.
* <p>
* This can be called on a different thread from the
* event dispatching thread and is basically unsafe to
* propagate into the component. To make this safe,
* the operation is transferred over to the event dispatching
* thread for completion. It is a design goal that all view
* methods be safe to call without concern for concurrency,
* and this behavior helps make that true.
*
* @param child the child view
* @param width true if the width preference has changed
* @param height true if the height preference has changed
*/
public void preferenceChanged(View child, boolean width, boolean height) {
host.revalidate();
host.repaint();
}
/**
* Determines the desired alignment for this view along an axis.
*
* @param axis may be either X_AXIS or Y_AXIS
* @return the desired alignment, where 0.0 indicates the origin
* and 1.0 the full span away from the origin
*/
public float getAlignment(int axis) {
return view.getAlignment(axis);
}
/**
* Renders the view.
*
* @param g the graphics context
* @param allocation the region to render into
*/
public void paint(Graphics g, Shape allocation) {
Rectangle alloc = allocation.getBounds();
view.setSize(alloc.width, alloc.height);
view.paint(g, allocation);
}
/**
* Sets the view parent.
*
* @param parent the parent view
*/
public void setParent(View parent) {
throw new Error("Can't set parent on root view");
}
/**
* Returns the number of views in this view. Since
* this view simply wraps the root of the view hierarchy
* it has exactly one child.
*
* @return the number of views
* @see #getView
*/
public int getViewCount() {
return 1;
}
/**
* Gets the n-th view in this container.
*
* @param n the number of the view to get
* @return the view
*/
public View getView(int n) {
return view;
}
/**
* Provides a mapping from the document model coordinate space
* to the coordinate space of the view mapped to it.
*
* @param pos the position to convert
* @param a the allocated region to render into
* @return the bounding box of the given position
*/
public Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException {
return view.modelToView(pos, a, b);
}
/**
* Provides a mapping from the document model coordinate space
* to the coordinate space of the view mapped to it.
*
* @param p0 the position to convert >= 0
* @param b0 the bias toward the previous character or the
* next character represented by p0, in case the
* position is a boundary of two views.
* @param p1 the position to convert >= 0
* @param b1 the bias toward the previous character or the
* next character represented by p1, in case the
* position is a boundary of two views.
* @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
* @exception IllegalArgumentException for an invalid bias argument
* @see View#viewToModel
*/
public Shape modelToView(int p0, Position.Bias b0, int p1,
Position.Bias b1, Shape a) throws BadLocationException {
return view.modelToView(p0, b0, p1, b1, a);
}
/**
* Provides a mapping from the view coordinate space to the logical
* coordinate space of the model.
*
* @param x x coordinate of the view location to convert
* @param y y coordinate of the view location to convert
* @param a the allocated region to render into
* @return the location within the model that best represents the
* given point in the view
*/
public int viewToModel(float x, float y, Shape a, Position.Bias[] bias) {
return view.viewToModel(x, y, a, bias);
}
/**
* Returns the document model underlying the view.
*
* @return the model
*/
public Document getDocument() {
return view.getDocument();
}
/**
* Returns the starting offset into the model for this view.
*
* @return the starting offset
*/
public int getStartOffset() {
return view.getStartOffset();
}
/**
* Returns the ending offset into the model for this view.
*
* @return the ending offset
*/
public int getEndOffset() {
return view.getEndOffset();
}
/**
* Gets the element that this view is mapped to.
*
* @return the view
*/
public Element getElement() {
return view.getElement();
}
/**
* Sets the view size.
*
* @param width the width
* @param height the height
*/
public void setSize(float width, float height) {
this.width = (int) width;
view.setSize(width, height);
}
/**
* Fetches the container hosting the view. This is useful for
* things like scheduling a repaint, finding out the host
* components font, etc. The default implementation
* of this is to forward the query to the parent view.
*
* @return the container
*/
public Container getContainer() {
return host;
}
/**
* Fetches the factory to be used for building the
* various view fragments that make up the view that
* represents the model. This is what determines
* how the model will be represented. This is implemented
* to fetch the factory provided by the associated
* EditorKit.
*
* @return the factory
*/
public ViewFactory getViewFactory() {
return factory;
}
private int width;
private View view;
private ViewFactory factory;
private JComponent host;
}
}
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