StylePad demo - scaling it

Question

Hi, I'm trying to modify the Stylepad demo (located in $JAVA_HOME/demo/jfc/Stylepad) so that it works 100% with a scaled instance of Graphics2D.
I've seen a bit of discussion around this (scaling/zooming a JTextPane/JTextComponent) - but I have yet to see a solution.
Just overriding JTextPane's paintComponen() method and serving it a scaled Graphics2D instance opened up a box of problems :) - to which I would appreciate solution suggestions to.
I've modified StylePad.java's createEditor() method. Here it is:
    protected JTextComponent createEditor() {
           StyleContext sc = new StyleContext();
           final DefaultStyledDocument doc = new DefaultStyledDocument();
              initDocument(doc, sc);
          final JTextPane p = new JTextPane(doc){
              public void paintComponent(Graphics g) {
                        Graphics2D g2d = (Graphics2D)g;
                     g2d.scale(0.5,0.5);
                     super.paintComponent(g2d);
                p.setCaret(new ScaledCaret()); // my custom caret
                p.addCaretListener(new CaretListener() {
                        public void caretUpdate(CaretEvent e) {
                            p.repaint();
             MouseInputAdapter mh = new MouseInputAdapter() {
                        public void mousePressed(MouseEvent e) {
                                p.repaint();
                       public void mouseDragged(MouseEvent e) {
                                p.repaint();
                p.addMouseListener(mh);
                p.addMouseMotionListener(mh);
                p.setDragEnabled(true);
     /* My own BasicTextPaneUI implementation, commented out for now
        ScaledTextUI sTextUI = new ScaledTextUI();
        p.setUI(sTextUI);
        return p;
    }The first problem I encountered was that the Caret position was all wrong. So, I created my own caret implementation that extends DefaultCaret. Remember that this is just test code to get it working with the scale 0.5,0.5 which I use in StylePad ..
import javax.swing.text.DefaultCaret;
import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
public class ScaledCaret extends DefaultCaret {
     * Moves the caret position
     * according to the mouse pointer's current
     * location.  This effectively extends the
     * selection.  By default, this is only done
     * for mouse button 1.
     * @param e the mouse event
     * @see MouseMotionListener#mouseDragged
    public void mouseDragged(MouseEvent e) {
        MouseEvent p = new MouseEvent((Component)e.getSource(),e.getID(),e.getWhen(),e.getModifiers(),(int)Math.round(e.getX()*2), (int)Math.round(e.getY()*2),e.getClickCount(),e.isPopupTrigger());
        super.mouseDragged(p);
     * Tries to set the position of the caret from
     * the coordinates of a mouse event, using viewToModel().
     * @param e the mouse event
    protected void positionCaret(MouseEvent e) {
        MouseEvent p = new MouseEvent((Component)e.getSource(),e.getID(),e.getWhen(),e.getModifiers(),(int)Math.round(e.getX()*2), (int)Math.round(e.getY()*2),e.getClickCount(),e.isPopupTrigger());
        super.positionCaret(p);
}That fixed the Caret positioning problems - but it still does not blink (once scaled the caret stops blinking).
The problem I am working with now is the size of the component.
If you run the StylePad demo with the above code you will experience problems with the painting of the JTextPane .. the ScrollPane obviously thinks its bigger than what it is, and around the JTextPane a lot of "rubbish" is painted.
My next step was creating a class extending BasicTextPaneUI. I did this, overriding getMaximumSize(), getPeferredSize() and getMinimumSize() to always return a specific dimension. It did not fix the problems I described above..
Hope someone takes an interest in this problem :)

Answer 1

Hi again,
I found out that the scaled painting should be done in the JTextPane's paintComponent method (this will affect all children). Doing them in the view's messed up things ..
I do however still have problems. Trying to implement your code everything looks pretty messed up.. Here's my EditorKit and ViewFactory if you would be kind enough to take a look at it:
    static class MyEditorKit extends StyledEditorKit implements ViewFactory {
      * Fetches a factory that is suitable for producing
      * views of any models that are produced by this
      * kit.  The default is to have the UI produce the
      * factory, so this method has no implementation.
      * @return the view factory
        public ViewFactory getViewFactory() {
         return this;
         * Creates an uninitialized text storage model (PlainDocument)
         * that is appropriate for this type of editor.
         * @return the model
        public Document createDefaultDocument() {
            return new DefaultStyledDocument();
      * THIS IS COPIED FROM StyledEditorKit
      * Creates a view from the given structural element of a
      * document.
      * @param elem  the piece of the document to build a view of
      * @return the view
      * @see View
      public View create(Element elem) {
         String kind = elem.getName();
         if (kind != null) {
          if (kind.equals(AbstractDocument.ContentElementName)) {
                    return new MyLabelView(elem);
          } else if (kind.equals(AbstractDocument.ParagraphElementName)) {
              return new MyParagraphView(elem);
          } else if (kind.equals(AbstractDocument.SectionElementName)) {
              return new MyBoxView(elem, View.Y_AXIS);
          } else if (kind.equals(StyleConstants.ComponentElementName)) {
              return new MyComponentView(elem);
          } else if (kind.equals(StyleConstants.IconElementName)) {
              return new IconView(elem);
         // default to text display
            return new LabelView(elem);
     }Here's an example of one of the view's (MyParagraphView since that is the one that is used frequently (always?):
        static class MyParagraphView extends javax.swing.text.ParagraphView {
            public MyParagraphView(Element elem) {
                super(elem);
                System.out.println("new MyParagraphView()");
             * Determines the minimum span for this view along an
             * axis.  This is implemented to provide the superclass
             * behavior after first making sure that the current font
             * metrics are cached (for the nested lines which use
             * the metrics to determine the height of the potentially
             * wrapped lines).
             * @param axis may be either View.X_AXIS or View.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.
             * @see View#getMinimumSpan
            public float getMinimumSpan(int axis) {
                float f = super.getMinimumSpan(axis);
                System.out.print("getMinimumSpan() from super ="+f+" .. ");
                if(axis == View.X_AXIS) {
                    f *= StylePadConstants.X_SCALE_FACTOR;
                } else {
                    f *= StylePadConstants.Y_SCALE_FACTOR;
                System.out.println("new ="+f);
                return f;
             * Determines the maximum span for this view along an
             * axis.  This is implemented to provide the superclass
             * behavior after first making sure that the current font
             * metrics are cached (for the nested lines which use
             * the metrics to determine the height of the potentially
             * wrapped lines).
             * @param axis may be either View.X_AXIS or View.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.
             * @see View#getMaximumSpan
            public float getMaximumSpan(int axis) {
                float f = super.getMaximumSpan(axis);
                if(axis == View.X_AXIS) {
                    f *= StylePadConstants.X_SCALE_FACTOR;
                } else {
                    f *= StylePadConstants.Y_SCALE_FACTOR;
                return f;
             * Determines the preferred span for this view along an
             * axis.  This is implemented to provide the superclass
             * behavior after first making sure that the current font
             * metrics are cached (for the nested lines which use
             * the metrics to determine the height of the potentially
             * wrapped lines).
             * @param axis may be either View.X_AXIS or View.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.
             * @see View#getPreferredSpan
            public float getPreferredSpan(int axis) {
                float f = super.getPreferredSpan(axis);
                System.out.print("getPreferredSpan() - from super="+f+"  .. ");
                if(axis == View.X_AXIS) {
                    f *= StylePadConstants.X_SCALE_FACTOR;
                } else {
                    f *= StylePadConstants.Y_SCALE_FACTOR;
                System.out.println("new="+f);
                return f;
             * Provides a mapping from the document model coordinate space
             * to the coordinate space of the view mapped to it.  This makes
             * sure the allocation is valid before calling the superclass.
             * @param pos the position to convert >= 0
             * @param a the allocated region to render into
             * @return the bounding box of the given position
             * @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 {
                Rectangle r = (Rectangle)super.modelToView(pos, a, b);
                r.x *= StylePadConstants.X_SCALE_FACTOR;
                r.y *= StylePadConstants.Y_SCALE_FACTOR;
                r.width *= StylePadConstants.X_SCALE_FACTOR;
                r.height *= StylePadConstants.Y_SCALE_FACTOR;
                return r;
             * 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 >= 0
             * @param y   y coordinate of the view location to convert >= 0
             * @param a the allocated region to render into
             * @return the location within the model that best represents the
             *  given point in the view >= 0
             * @see View#viewToModel
            public int viewToModel(float x, float y, Shape a, Position.Bias[] bias) {
                float newx = (float)(x*StylePadConstants.X_SCALE_FACTOR);
                float newy = (float)(y*StylePadConstants.Y_SCALE_FACTOR);
                Rectangle r = a.getBounds();
                r.x *= StylePadConstants.X_SCALE_FACTOR;
                r.y *= StylePadConstants.Y_SCALE_FACTOR;
                r.width *= StylePadConstants.X_SCALE_FACTOR;
                r.height *= StylePadConstants.Y_SCALE_FACTOR;
                int i = super.viewToModel(newx, newy, r, bias);
                return i;
        }What happens is that text elements are displayed on top of other text elements etc.
All the other views (MyBoxView etc.) contains the same code as the one above. I copied the create() method from StyledEditorKit's ViewFactory.
StylePadConstants merely contains the x/y scale factor.
Best regards,
Bjorn