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Development Team/Almanac/GTK's Clipboard Module (view source)
Revision as of 14:55, 25 July 2008
, 14:55, 25 July 2008→How do I work with multiple clipboards in my activity?
=== How do I work with multiple clipboards in my activity? ===
=== How do I work with multiple clipboards in my activity? ===
First, you need to create [[#How_do_I_create_my_own_named_clipboard.3F | named clipboards]] for each context that you will be saving data.
There are many cases where you might want to have multiple clipboards to save and share activity data. I'll use a very basic example from which readers can get the general idea about multiple clipboards and adapt to their own unique needs. In this example, we have a notebook widget with several pages and we want data that is copied from a specific page available only to the same page in other instances of the same activity.
So how do we accomplish this?
First, you need to create [[#How_do_I_create_my_own_named_clipboard.3F | named clipboards]] for each context that you will be saving data. In our case, we have two notebook pages and will create two separate clipboards (one for each page).
<pre>
#### Method: _createCanvas, creates a top level canvas object for this activity
def _createCanvas(self):
top_container = Notebook()
#Create pages for the notebook
first_page = gtk.VBox()
second_page = gtk.VBox()
#Create a clipboard specifically for data on the first page of this activity's notebook
self.pg1_clipboard = gtk.clipboard_get('ANNOTATE_CLIPBOARD_1')
#Create a clipboard specifically for data on the second page of this activity's notebook
self.pg2_clipboard = gtk.clipboard_get('ANNOTATE_CLIPBOARD_2')
</pre>
The UI for each page in our notebook is pretty much identical, except that the widgets will be identified uniquely based on which page they happen to be in. The code below creates a simple UI for each page with a text entry widget, a copy button and a paste button.
<pre>
#FOR FIRST PAGE:: Create a text entry box with two buttons for copy and paste right below it.
first_page_entry_box = gtk.VBox(homogeneous=False, spacing=5)
button_row = gtk.HBox()
#### Create the actual gtk.Entry for text entry
self.clipInput1 = gtk.Entry(max=0)
self.clipInput1.set_width_chars(100)
#### Create the copy button and assign callback
copyClipInput1 = gtk.Button(label='Copy Text')
copyClipInput1.connect("clicked", self._copyClipInput1_cb, None)
button_row.pack_start(copyClipInput1, expand=False, fill=False)
#### Create the paste button and assign callback
pasteClipInput1 = gtk.Button(label='Paste Text')
pasteClipInput1.connect("clicked", self._pasteClipInput1_cb, None)
#### Put everything together in the UI
button_row.pack_start(copyClipInput1, expand=False, fill=False)
button_row.pack_start(pasteClipInput1, expand=False, fill=False)
button_row.pack_start(gtk.Label(''), expand=True, fill=True) #for appearance purposes
first_page_entry_box.pack_start(self.clipInput1, expand=False, fill=False)
first_page_entry_box.pack_start(button_row, expand=False, fill=False)
first_page.pack_start(first_page_entry_box)
first_page.pack_start(gtk.Label(''), expand=True, fill=True) #for appearance purposes
#FOR SECOND PAGE:: Create a text entry box with two buttons for copy and paste right below it.
second_page_entry_box = gtk.VBox(homogeneous=False, spacing=5)
button_row = gtk.HBox()
#### Create the actual gtk.Entry for text entry
self.clipInput2 = gtk.Entry(max=0)
self.clipInput2.set_width_chars(100)
#### Create the copy button and assign callback
copyClipInput2 = gtk.Button(label='Copy Text')
copyClipInput2.connect("clicked", self._copyClipInput2_cb, None)
button_row.pack_start(copyClipInput2, expand=False, fill=False)
#### Create the paste button and assign callback
pasteClipInput2 = gtk.Button(label='Paste Text')
pasteClipInput2.connect("clicked", self._pasteClipInput2_cb, None)
#### Put everything together in the UI
button_row.pack_start(copyClipInput2, expand=False, fill=False)
button_row.pack_start(pasteClipInput2, expand=False, fill=False)
button_row.pack_start(gtk.Label(''), expand=True, fill=True) #for appearance purposes
second_page_entry_box.pack_start(self.clipInput2, expand=False, fill=False)
second_page_entry_box.pack_start(button_row, expand=False, fill=False)
second_page.pack_start(second_page_entry_box)
second_page.pack_start(gtk.Label(''), expand=True, fill=True) #for appearance purposes
</pre>
The rest of the work will be done when either the "Copy" or "Paste" buttons are pressed. In this case, the callbacks we bind using the connect() method above will be invoked.
Below are the virtually identical callbacks for the two pages in our activity. The only difference is that they reference different clipboard objects, so that each page has its own set of clipboard data that it manipulates.
<pre>
#### Method: _copyClipInput1_cb, which is called when the "Copy Text" button is clicked
def _copyClipInput1_cb(self, widget, data=None):
#Select all text in self.copyClipInput and copy it to the clipboard
self.pg1_clipboard.set_text(self.clipInput1.get_text())
_logger.debug("$$$$$$$$$$$$$$$$$$$ Copy button on First Page pressed")
#### Method: _pasteClipInput1_cb, which is called when the "Paste Text" button is clicked
def _pasteClipInput1_cb(self, widget, data=None):
self.clipInput1.set_text(self.pg1_clipboard.wait_for_text())
_logger.debug("******************* Paste button on First Page pressed.")
#### Method: _copyClipInput2_cb, which is called when the "Copy Text" button is clicked
def _copyClipInput2_cb(self, widget, data=None):
#Select all text in self.copyClipInput and copy it to the clipboard
self.pg2_clipboard.set_text(self.clipInput2.get_text())
_logger.debug("$$$$$$$$$$$$$$$$$$$ Copy button on Second Page pressed")
#### Method: _pasteClipInput2_cb, which is called when the "Paste Text" button is clicked
def _pasteClipInput2_cb(self, widget, data=None):
self.clipInput2.set_text(self.pg2_clipboard.wait_for_text())
_logger.debug("******************* Paste button on Second Page pressed.")
</pre>
= Working with More Complex Data Structures on the Clipboard =
= Working with More Complex Data Structures on the Clipboard =