[GTK4] Implement Clipboard.getAvailableTypes()

[ptziegler]

The list of available types is calculated using the GDK4 clipboard and
no longer falls back to the GTK3 bindings.

Note that UTF8_STRING, COMPOUND_TEXT and STRING_ID are not implemented
for GTK4, which is why those types must not be used in the TextTransfer,
regardless of whether X11 or Wayland is used.

[github-actions]

Test Results

   408 files   -   137     408 suites   - 137   19m 4s ⏱️ - 11m 57s
 4 332 tests  -    37   4 322 ✅  -    35  10 💤  -  2  0 ❌ ±0 
12 521 runs   - 4 103  12 424 ✅  - 4 090  97 💤  - 13  0 ❌ ±0 

Results for commit de14b38. ± Comparison against base commit 0fe4a76.

This pull request removes 37 tests.

AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicASCII_dollarSign
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicASCII_emptyString
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicASCII_letterA
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicASCII_letters
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicUTF16LE_null
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicUTF16_AsciiLetters
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicUTF16_Asciiletter
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicUTF16_LotsOfLetters
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicUTF16_letter
AllGTKTests org.eclipse.swt.tests.gtk.Test_GtkConverter ‑ test_HeuristicUTF16_letters
…

♻️ This comment has been updated with latest results.

[akurtakov]

Doesn't this PR practically disable clipboard functionality almost entirely?

[ptziegler]

Doesn't this PR practically disable clipboard functionality almost entirely?

Yes. But as mentioned, the clipboard is not implemented for GTK4. This method internally calls getAvailableClipboardTypes() and/or getAvailablePrimaryTypes(), which then calls gtk_clipboard_wait_for_contents().

The last method uses GTK3-only methods which will always cause an UnsatisfiedLinkError.

eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/gtk/org/eclipse/swt/dnd/Clipboard.java

Lines 696 to 711 in 0f21a6e

	long gtk_clipboard_wait_for_contents(long clipboard, long target) {
	long startTime = System.currentTimeMillis();
	String key = "org.eclipse.swt.internal.gtk.dispatchEvent";
	Display display = this.display;
	display.setData(key, new int[]{GDK.GDK_PROPERTY_NOTIFY, GDK.GDK_SELECTION_CLEAR, GDK.GDK_SELECTION_REQUEST, GDK.GDK_SELECTION_NOTIFY});
	long selection_data = GTK3.gtk_clipboard_wait_for_contents(clipboard, target);
	display.setData(key, null);
	long duration = System.currentTimeMillis() - startTime;
	if (selection_data == 0 && duration > 5000) {
	// Bug 241957: In case of timeout take clipboard ownership to unblock future calls
	ClipboardProxy._getInstance(display).setData(this, new String[] {" "},
	new Transfer[] { TextTransfer.getInstance() },
	clipboard == GTKCLIPBOARD ? DND.CLIPBOARD : DND.SELECTION_CLIPBOARD);
	}
	return selection_data;
	}

[laeubi]

But as mentioned, the clipboard is not implemented for GTK4.

I'm not sure if it is relevant but GDK4 seems to have a clipboard class.

https://docs.gtk.org/gdk4/class.Clipboard.html

and this seems to be the method to use for getting the formats:

https://docs.gtk.org/gdk4/method.Clipboard.get_formats.html

so can we sue this or is there a subtile difference between GTK and GDK that makes it impossible?

[akurtakov]

In Gtk 3.x gdk used to be its own library but in Gtk 4.x gdk library has been merged into main libgtk. @ptziegler Would you look into that? If not give me few days and I'll try to look into it myself.

[ptziegler]

The GDK clipboard is already used in some places but the implementation is not yet complete.

eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/gtk/org/eclipse/swt/dnd/Clipboard.java

Lines 44 to 51 in 0f21a6e

	static {
	GTKCLIPBOARD = GTK.GTK4 ? GDK.gdk_display_get_clipboard(GDK.gdk_display_get_default()) : GTK3.gtk_clipboard_get (GDK.GDK_NONE);
	byte[] buffer = Converter.wcsToMbcs("PRIMARY", true);
	long primary = GTK.GTK4 ? 0 : GDK.gdk_atom_intern(buffer, false);
	GTKPRIMARYCLIPBOARD = GTK.GTK4 ? GDK.gdk_display_get_primary_clipboard(GDK.gdk_display_get_default()) : GTK3.gtk_clipboard_get(primary);
	buffer = Converter.wcsToMbcs("TARGETS", true);
	TARGET = GTK.GTK4 ? 0 : GDK.gdk_atom_intern(buffer, false);
	}

Would you look into that?

I can try to have a look what else is needed to complete this port, but I currently have to deal with allergy & stuff, so no promises...

[ptziegler]

I've updated the PR to instead implement the GTK4 case, rather than disabling it.

Recording.webm

[ptziegler]

As a side note: I've tested this together with #1984 and quite often the copy & paste actions in the popup menu don't work and the following error is logged.

(SWT:140252): Gtk-WARNING **: 20:10:05.026: Broken accounting of active state for widget 0x72becc95af10(GtkPopoverMenu)

This seems to be a GTK4 bug: https://gitlab.gnome.org/GNOME/gtk/-/issues/4563

[akurtakov]

For some reason the Linux GHA seems to switched to on run GTK4. As it's not due to this change and it actually fixes a crash I am ignoring it and merging.

[laeubi]

For some reason the Linux GHA seems to switched to on run GTK4.

This is because the GTK4 label was added to this PR!

Jenkins will still compile/run on GTK3.