Pasting Selection With Middle-Click

There is another type of paste operation that is supported on Linux, specifically by the X11 window system used by Linux and MAC-OS.  The selection is made using the mouse by clicking at the start of the text and dragging to the end of the text.  This selection can then be pasted into any window using the middle mouse button (the button under the wheel on most modern mice).  Windows does not support this feature.

This paste operation is intercepted by reimplementing the mouse release event handler.  If the event has the middle mouse button, the clipboard is checked to see if it supports this type of selection.  If it does, the text() function is again used to obtain the text of the selection, however, instead of using the default argument (nothing), the QClipboard::Selection argument is used to get this selection text instead of the normal clipboard paste buffer text.  Otherwise, the mouse release event is passed to the mouse release event handler of the QPlainTextEdit base class.

There is one issue with this paste operation however.  The text is pasted at the current location of the text cursor, not where the mouse cursor is actually pointing to at the time of the middle button click.  This will be the subject of next post.

[commit 9d1c0780e8]

Changed Lines From Pasting

In order to detect lines that may be modified of inserted text from pasting, the text that is about to be inserted from the clipboard needs to be intercepted and examined to see what is about to be inserted.  To catch the paste action, the paste function was reimplemented in the EditBox class.  The paste key sequence also needed to be intercepted, so the key press event handler was modified to also call this new paste function for the paste key sequence.

In the new paste function, a pointer to the clipboard is obtained from the static QApplication::clipboard() function.  The plain text contents of the clipboard is obtained by calling text() function.  Since the existing function for inserting a new line contained a subset of the code needed for inserting text which may contain new lines.  So this function was modified to handle more than just inserting a single new line.  This new function is called for the return key with a string containing a single new line character.

The insert text function handles determining whether the current line (before inserting the text) needs to be reported as changed, if any new lines need to be reported as inserted, and what to set the modified status of the cursor line once the text has been inserted.  Right now this function only handles a paste when there is no text selected.

[commit 8b46b474f1]