Introduction
Try to copy some text as html into the windows clipboard with jdk1.3/1.4 (others not tested).
Some other applications don't accept this as valid data. Known as:
not working: Eudora 5.1 and OpenOfficeWriter 1.0.1.
working: OpenOfficeCalc 1.0.1, also Word2000, Dreamweaver4 and XMLSpy4 are told me to work.
If you put data into the clipboard with a RepresentationClass other than
java.lang.String doesn't/shouldn't work with any application.
Windows html clipboard format
Html as a clipboard format is registered in Windows with the identifier 'HTML Format'. The data-format is text, something like this:
Version:1.0 StartHTML:0000000000 EndHTML:0000000000 StartFragment:0000000000 EndFragment:0000000000 <!--StartFragment--> ... <!-- EndFragment-- >
- '...' is the html-data you want to put into the clipboard.
- The numbers '0000000000' are byte-offsets from the start of the whole block, StartHTML & EndHTML may be -1 (see links) and java sets them to -1.
- All data has to be in the utf-8 charset.
- For more options and details see the links
Links
HTML Clipboard Format
, or here:
nearly the same
274326 - HOWTO: Add HTML Code to the Clipboard by Using Visual Basic, Sun look here!
Clipboard inspecting tool
I have written a small native (win) application to inspect the clipboard in a nearly raw way.
Get it
Bugs in other applications
A little test helps to find out what is wrong with some destination applications. They can't handle StartHTML & EndHTML set to -1. If you set them to real values all works fine. Oddly enough Eudora doesn't understand its own Html Format.
Bug in Java
If you use a RepresentationClass other than java.lang.String
the html-data is wrapped twice with the envelope, so applications see something odd.
Example result:
Version:0.9 StartHTML:-1 EndHTML:-1 StartFragment:0000000111 EndFragment:0000000417 <!--StartFragment--> Version:0.9 StartHTML:-1 EndHTML:-1 StartFragment:0000000111 EndFragment:0000000286 <!--StartFragment--> Version:0.9 StartHTML:00000000108 EndHTML:00000000168 StartFragment:00000000108 EndFragment:00000000168 <!--StartFragment--><b>Example text</b><!--EndFragment-->
Reason: If you look at the code below you can
see that first super.translateTransferable() is called, afterwards
HTMLSupport.convertToHTMLFormat(). The bug is in the superclass DataTransferer
when, if the RepresentationClass isn't String, the data is converted
to String and recursively translateTransferable() is called. After the second
return the data is wrapped two times.
Java - Workaround
First, use only String as RepresentationClass to put html
into the clipboard to avoid the double wrapper.
For the interaction with other programs, i don't know a clean one. Since some of the important methods in WClipboard are private, you have to get access with reflection, and become really dependant from the underlying implementation, see below.
It probably works to exchange the class HTMLSupport with bootclasspath
(see 'java.exe -X'), you only want this for your own computer. Or try to use
your own classloader to inject a new class.
SystemFlavorMap - mapping of native/DataFlavor
I tried to overwrite the default mapping of native/DataFlavor by playing around with:
SystemFlavorMap.getDefaultFlavorMap() SystemFlavorMap.setNativesForFlavor(...) SystemFlavorMap.addUnencodedNativeForFlavor(...)
but this doesn't help.
A reason is in sun.awt.windows.WDataTransferer here the snippet:
public byte[] translateTransferable( Transferable transferable,
DataFlavor dataflavor,
long nativeFormat) throws IOException{
byte data[] = super.translateTransferable( transferable,
dataflavor,
nativeFormat);
if(nativeFormat == CF_HTML) data = HTMLSupport.convertToHTMLFormat(data);
return data;
}
They always compare to the native format, so it is always translated in the standard way.
Even if one uses a different DataFlavor, e.g. 'text/myOwn' which i may map to the
native 'Html Format'. Using a different
native Format is possible, but then other applications doesn't know about this.
Another disadvantage of the 'default enveloping' is, that one can't use the advanced
features of the windows-clipboardformat by placing some info into the header
(see Links above):
- Offer a selection in the context of a whole page
- Extra info like source URL
Workaround to interact with buggy software
Access the native clipboard, windows only, write only.
Needs work to become fool-proof, you may look into WClipboard.
Since this class hacks a private method, it may be harmful if
the underlying implementation is changed.
Also, some knowledge about the native format is needed, e.g. plain text needs a null char at the end.
To get access to the native windows clipboard: PEBClip.java
Transform html to Windows clipboard format: PEBHtmlSupport.java
Test class: Test.java