Clipboard

The clipboard is a mechanism provided by PM to allow the user to transfer data between different applications. To do so, the user selects some data in a window, "copies" (or "cuts") it to the clipboard and then "pastes" the data in the target application.

When dealing with bidirectional data, it may be required to transfer text data, that has different bidirectional attributes (i.e, different format of text) between applications. Accordingly, a conversion of the text must be performed, in order to transform the text to a format (identified by bidirectional attributes) which is compatible with the target application (the one that "pastes" the data).

The PM bidirectional support provides automatic conversion of text between source and target applications, based on their process bidirectional attributes. In addition, bidi-aware applications can explicitly set the bidirectional attributes managed by the clipboard in order to affect the conversion that is performed on the text.

In order to allow the automatic conversion of the clipboard, the following conditions must be met:

• Both the source and the target applications have valid process bidirectional attributes (i.e, their bidi attributes are not 0).

• Exchange of CF_TEXT and CF_DSPTEXT format is performed.

• The source and target bidi attributes are different.

• None of the applications (i.e, neither the source application nor the target one) have issued any APIs to cancel the conversion provided by the clipboard.

The clipboard maintains two sets of bidirectional attributes.

The first set is called the 'Clipboard Bidirectional Attributes' and is associated with the text data that is currently stored in the clipboard. The default value for this set is inherited from the process bidirectional attributes of the application that issues WinSetClipbrdData. The source application can optionally modify this set of attributes by using the WinSetLangInfo API with the LI_BD_CLIP_ATTR effect.

The second set is called the 'Conversion Bidirectional Attributes'. This set is associated with the target application, and its default value is inherited from the process bidirectional attributes of the application that issues the WinQueryClipbrdData API. The target application can optionally modify these attributes by using the WinSetLangInfo API with LI_BD_CLIP_CONV_ATTR effect.

When using the WinSetLangInfo API to change the clipboard data, bidi-aware applications must follow the following rules:

• Setting of both the 'Clipboard bidi attributes' and the 'conversion bidi attributes' must be performed only when an application has access to the clipboard - i.e, after issuing WinOpenClipbrd and before issuing the WinCloseClipbrd APIs.

• Setting LI_BD_CLIP_ATTR must be done AFTER data has been put into the clipboard (that is, after issuing WinSetClipbrdData).

The following is a typical scenario. Lines marked with '(BD)' are optional, and can be issued by bidi-aware applications.

  Setting Clipboard Bidirectional Data.  -------------------------------------

  WinOpenClipbrd()
  WinEmptyClipbrd()
  WinSetClipbrdData(CF_TEXT)     (clipboard bidi attributes are set -
                                  inheited from process bidi attributes).

  (BD) WinSetLangInfo(LI_BD_CLIP_ATTR..) (clipboard bidi attribute are set)

  WinCloseClipbrd()


  Querying Clipboard Bidirectional Data
  --------------------------------------

   WinOpenClipbrd()

   (BD) WinQueryLangInfo(LI_BD_CLIP_ATTR...)
                                  (Queries the current clipboard
                                   bidi attributes).
   (BD) WinSetLangInfo(LI_BD_CLIP_CONV_ATTR...)
                                  (sets the clipboard conversion
                                   bidi attributes).
    WinQueryClipbrdData(CF_TEXT)   (clipboard performs conversion on
                                    the text, using the clipboard
                                    and the conversion bidi attributes.
    WinCloseClipbrd()