Hi All,
We (HSLF developers) are searching for good object model to work with the
character and paragraph styles.
It would be good to discuss a possible architecture and know your opinions,
before we settle. Working with text is a key feature of a PowerPoint API and
this discussion won't harm. :))
A possible solution to handle character styles is to use
java.text.AttributedString, a standard Java class
which is meant for working with format runs in Java2D.
Use cases may look as follows:
(a) Create a text box and set character format:
org.apache.poi.hslf.model.TextRun txrun = ...; //HSLF object which represents a
run of text in a powerpoint document
String text = "Hello, World";
txrun.settext(text)
AttributedString str = txrun.getCharacterStyle();
str.addAttribute(TextAttribute.FAMILY, "Arial"); //set the font family to the
entire string
str.addAttribute(TextAttribute.SIZE, new Float(32), 0, 5); //set the font size
to a a subrange
str.addAttribute(TextAttribute.FOREGROUND, Color.red, 3, 6);//set the font
color to a a subrange
(b) For a text run read format runs or get attributes at the specified position:
org.apache.poi.hslf.model.TextRun txrun = ...;
String text = txrun.getText();
AttributedString str = txrun.getCharacterStyle();
//iterate over format runs
AttributedCharacterIterator it = str.getIterator();
int index = 0;
while (index < it.getEndIndex()) {
it.setIndex(index);
inr runLimit = it.getRunLimit();
Map attrs = it.getAttributes();
String fragment = text.substring(index , runLimit);
System.out.println("[" + fragment + "]: "+ attrs);
index = runLimit;
}
//get format attributes at the specified position:
it.setIndex(8);
Map attr = it.getAttributes();
System.out.println("attributes at position 8: " + attr);
Advantages of this approach:
- there are lots of docs on Java2D and people can use their previous experience
or read recommended books to learn more how to use java.text.AttributedString.
- This part of HSLF becomes compatible with Java graphics.
Users can use the AttributedString object to paint the string using
java.awt.Graphics:
Graphics2D.drawString(AttributedCharacterIterator iterator, float x, float y)
should output something similar to what you see in PowerPoint.
- We don't need any special objects to handle stylings. (Currently we
have RichTextRun object with getters and setters for font name, font
size, bold/italic/underline, etc). All is done via the standard methods
of java.text.AttributedString.
Drawbacks:
- My main concern is that the exposing of AttributedString may not be
user-friendly.
Also I'm not sure if this approach will fit for working with paragraph styles.
I think that the API to work with paragraph styles should be symmetrical, i.e.
set paragraph attributes via AttributedString:
AttributedString str = txrun.getParagraphStyle();
//do paragraph styling
So, I would like to hear you comments. Also, If anyone knows a good
alternative to the suggested architecture - please share your
knowledge.
Regards,
Yegor Kozlov
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