I made my custom HTMLEditorKit, which can increase / decrease HTML content in JEditorPane, it even improves rendering performance, I called it LargeHTMLEditorKit :
public class LargeHTMLEditorKit extends HTMLEditorKit {
ViewFactory factory = new MyViewFactory();
@Override
public ViewFactory getViewFactory() {
return factory;
}
class MyViewFactory extends HTMLFactory {
@Override
public View create(Element elem) {
AttributeSet attrs = elem.getAttributes();
Object elementName = attrs.getAttribute(AbstractDocument.ElementNameAttribute);
Object o = (elementName != null) ? null : attrs.getAttribute(StyleConstants.NameAttribute);
if (o instanceof HTML.Tag) {
HTML.Tag kind = (HTML.Tag) o;
if (kind == HTML.Tag.HTML) {
return new HTMLBlockView(elem);
}
else if (kind == HTML.Tag.IMPLIED) {
String ws = (String) elem.getAttributes().getAttribute(CSS.Attribute.WHITE_SPACE);
if ((ws != null) && ws.equals("pre")) {
return super.create(elem);
}
return new HTMLParagraphView(elem);
} else if ((kind == HTML.Tag.P) ||
(kind == HTML.Tag.H1) ||
(kind == HTML.Tag.H2) ||
(kind == HTML.Tag.H3) ||
(kind == HTML.Tag.H4) ||
(kind == HTML.Tag.H5) ||
(kind == HTML.Tag.H6) ||
(kind == HTML.Tag.DT)) {
return new HTMLParagraphView(elem);
}
}
return super.create(elem);
}
}
private class HTMLBlockView extends BlockView {
public HTMLBlockView(Element elem) {
super(elem, View.Y_AXIS);
}
@Override
protected void layout(int width, int height) {
if (width<Integer.MAX_VALUE) {
super.layout(new Double(width / getZoomFactor()).intValue(),
new Double(height *
getZoomFactor()).intValue());
}
}
public double getZoomFactor() {
Double scale = (Double) getDocument().getProperty("ZOOM_FACTOR");
if (scale != null) {
return scale.doubleValue();
}
return 1;
}
@Override
public void paint(Graphics g, Shape allocation) {
Graphics2D g2d = (Graphics2D) g;
double zoomFactor = getZoomFactor();
AffineTransform old = g2d.getTransform();
g2d.scale(zoomFactor, zoomFactor);
super.paint(g2d, allocation);
g2d.setTransform(old);
}
@Override
public float getMinimumSpan(int axis) {
float f = super.getMinimumSpan(axis);
f *= getZoomFactor();
return f;
}
@Override
public float getMaximumSpan(int axis) {
float f = super.getMaximumSpan(axis);
f *= getZoomFactor();
return f;
}
@Override
public float getPreferredSpan(int axis) {
float f = super.getPreferredSpan(axis);
f *= getZoomFactor();
return f;
}
@Override
public Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException {
double zoomFactor = getZoomFactor();
Rectangle alloc;
alloc = a.getBounds();
Shape s = super.modelToView(pos, alloc, b);
alloc = s.getBounds();
alloc.x *= zoomFactor;
alloc.y *= zoomFactor;
alloc.width *= zoomFactor;
alloc.height *= zoomFactor;
return alloc;
}
@Override
public int viewToModel(float x, float y, Shape a,
Position.Bias[] bias) {
double zoomFactor = getZoomFactor();
Rectangle alloc = a.getBounds();
x /= zoomFactor;
y /= zoomFactor;
alloc.x /= zoomFactor;
alloc.y /= zoomFactor;
alloc.width /= zoomFactor;
alloc.height /= zoomFactor;
return super.viewToModel(x, y, alloc, bias);
}
}
}
And here HTMLParagraphView is required :
class HTMLParagraphView extends ParagraphView {
public static int MAX_VIEW_SIZE=100;
public HTMLParagraphView(Element elem) {
super(elem);
strategy = new HTMLParagraphView.HTMLFlowStrategy();
}
public static class HTMLFlowStrategy extends FlowStrategy {
protected View createView(FlowView fv, int startOffset, int spanLeft, int rowIndex) {
View res=super.createView(fv, startOffset, spanLeft, rowIndex);
if (res.getEndOffset()-res.getStartOffset()> MAX_VIEW_SIZE) {
res = res.createFragment(startOffset, startOffset+ MAX_VIEW_SIZE);
}
return res;
}
}
public int getResizeWeight(int axis) {
return 0;
}
}
Then you can use it as follows:
//Create a new JEditorPane
JEditorPane yourPane = new JEditorPane();
//Set the custom HTMLEditorKit
yourPane.setEditorKit(new LargeHTMLEditorKit());
//Set the zoom to 150%
yourPane.getDocument().putProperty("ZOOM_FACTOR", new Double(1.5));