Dragging files to other applications
It seems that Gtk 1.x on windows allows you to receive drops from
other windows programs, but not to drag outside the application.
This means you can use DnD inside your PHP-Gtk application, but
use drop only when communicating with other programs.
The good news: Unlike the drop problems, all tested programs (Konqueror,
Kate, Firefox, Opera, Nautilus) seem to be able to handle correct URIs
dragged to them in the right way. Even Firefox accepts
text/uri-list data.
The first step is again to tell the widget that it has the ability
to act as a source for drag data. Furthermore, we need to provide
the data we want to drag, which can be done by connecting the widget
to the "drag-data-get"
signal.
Example 4.7. Setting up the drag source
//at the end of buildDialog()
$this->tree->drag_source_set(GDK_BUTTON1_MASK, $this->targets, GDK_ACTION_COPY);
$this->tree->connect('drag-data-get', array(&$this, 'dragDataGet'));
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We told the widget the following:
-
Act as a drag source when the user uses the first (mostly left)
mouse button
-
Provide one format for the dragging data, namely
text/uri-list
-
Require the drop target to copy the file, not to move it.
-
When the target widget demands for the data, call the
dragDataGet function of our class.
Next is to provide the data for the drop target in the
dragDataGet function:
Example 4.8. Setting the data to drag
function dragDataGet( $tree, $context, $selection_data, $info, $time) {
if( count( $tree->selection) < 1) { return false; }
$node = $tree->selection[0];
$file = $tree->node_get_text( $node, 2);
if( $file == '') { return false; }
$selection_data->set($selection_data->target, 8, urlencode($this->getUriFromFile($file)) . "\r\n");
}
/**
* converts a file name to a URI
* useful to convert a file to the text/uri-list compatible format
* @param string The file
* @return string The URI
*/
function getUriFromFile( $strFile) {
if (strstr($strFile, '://')) {
//real URL
$strUri = $strFile;
} else {
//normal file
if (substr($strFile, 1, 2) == ':\\') {
//windows path c:\programs\bla\blu\file.bli
$strUri = 'file://localhost/' . str_replace('\\', '/', $strFile);
} else {
//should be nice unix file
//@fixme: convert relative names to absolute ones?
$strUri = 'file://localhost' . realpath($strFile);
}
}
return $strUri;
}
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The data are passed by overwriting the selection data via the
set() method of the
selection_data. As we want to follow the
standards, the file name has to be converted to a full-flagged
url-encoded URI, with the terminating \r\n at
the end of the line. When nothing is selected in the tree, we don't
change the selection data.
When trying to drag a file to your favorite application, you will
note that nothing happens. Why? The URI passed to the program looks
like that: file%3A%2F%2Flocalhost%2Fdata%2Fphp-gtk.
Yes, urlencode doesn't take care of the character's
meaning in the URI. Now it would cost some effort to make a function
which does a correct encoding while taking care of special characters,
as http URIs can contain slashes in a parameter which would have to be
encoded, but slashes in the filename not. For that reason, only a
simple back-translation of some chars is done after urlencoding the
string:
Example 4.9. urlencode replacement
function pathurlencode($uri) {
$uri = urlencode($uri);
$uri = str_replace('%3A', ':', $uri);
$uri = str_replace('%2F', '/', $uri);
$uri = str_replace('%26', '&', $uri);
$uri = str_replace('%40', '@', $uri);
$uri = str_replace('%3A', ':', $uri);
$uri = str_replace('%3F', '?', $uri);
return $uri;
}
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With that, we can change our dragDataGet function:
$selection_data->set($selection_data->target, 8, $this->pathurlencode($this->getUriFromFile($file)) . "\r\n");
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