Retry OpenClipboard if it fails as another application may have opened it.

3 files changed, 27 insertions, 5 deletions

diff --git a/doc/ScintillaHistory.html b/doc/ScintillaHistory.html
index 6bdcb1e5d..1c5f2f356 100644
--- a/doc/ScintillaHistory.html
+++ b/doc/ScintillaHistory.html
@@ -538,6 +538,10 @@
 	<li>
 	IME target range displayed on Qt for OS X.
 	</li>
+	<li>
+	On Windows, make clipboard operations more robust by retrying OpenClipboard if it fails
+	as this may occur when another application has opened the clipboard.
+	</li>
     </ul>
     <h3>
        <a href="http://www.scintilla.org/scite363.zip">Release 3.6.3</a>
diff --git a/test/simpleTests.py b/test/simpleTests.py
index c7240b269..62243dd49 100644
--- a/test/simpleTests.py
+++ b/test/simpleTests.py
@@ -493,13 +493,15 @@ class TestSimple(unittest.TestCase):
 		self.ed.AddText(5, b"a1b2c")
 		self.ed.SetSel(1,3)
 		self.ed.Cut()
-		self.xite.DoEvents()
+		# Clipboard = "1b"
+		self.assertEquals(self.ed.Contents(), b"a2c")
 		self.assertEquals(self.ed.CanPaste(), 1)
 		self.ed.SetSel(0, 0)
 		self.ed.Paste()
 		self.assertEquals(self.ed.Contents(), b"1ba2c")
 		self.ed.SetSel(4,5)
 		self.ed.Copy()
+		# Clipboard = "c"
 		self.ed.SetSel(1,3)
 		self.ed.Paste()
 		self.assertEquals(self.ed.Contents(), b"1c2c")
@@ -508,13 +510,12 @@ class TestSimple(unittest.TestCase):
 		self.assertEquals(self.ed.Contents(), b"1c")
 
 	def testCopyAllowLine(self):
-		self.xite.DoEvents()
 		lineEndType = self.ed.EOLMode
 		self.ed.EOLMode = self.ed.SC_EOL_LF
 		self.ed.AddText(5, b"a1\nb2")
 		self.ed.SetSel(1,1)
 		self.ed.CopyAllowLine()
-		self.xite.DoEvents()
+		# Clipboard = "a1\n"
 		self.assertEquals(self.ed.CanPaste(), 1)
 		self.ed.SetSel(0, 0)
 		self.ed.Paste()
diff --git a/win32/ScintillaWin.cxx b/win32/ScintillaWin.cxx
index c9a712df2..2e9cce34a 100644
--- a/win32/ScintillaWin.cxx
+++ b/win32/ScintillaWin.cxx
@@ -2184,9 +2184,25 @@ public:
 	}
 };
 
+// OpenClipboard may fail if another application has opened the clipboard.
+// Try up to 8 times, with an initial delay of 1 ms and an exponential back off
+// for a maximum total delay of 127 ms (1+2+4+8+16+32+64).
+static bool OpenClipboardRetry(HWND hwnd) {
+	for (int attempt=0; attempt<8; attempt++) {
+		if (attempt > 0) {
+			::Sleep(1 << (attempt-1));
+		}
+		if (::OpenClipboard(hwnd)) {
+			return true;
+		}
+	}
+	return false;
+}
+
 void ScintillaWin::Paste() {
-	if (!::OpenClipboard(MainHWND()))
+	if (!::OpenClipboardRetry(MainHWND())) {
 		return;
+	}
 	UndoGroup ug(pdoc);
 	const bool isLine = SelectionEmpty() &&
 		(::IsClipboardFormatAvailable(cfLineSelect) || ::IsClipboardFormatAvailable(cfVSLineTag));
@@ -2737,8 +2753,9 @@ void ScintillaWin::GetIntelliMouseParameters() {
 }
 
 void ScintillaWin::CopyToClipboard(const SelectionText &selectedText) {
-	if (!::OpenClipboard(MainHWND()))
+	if (!::OpenClipboardRetry(MainHWND())) {
 		return;
+	}
 	::EmptyClipboard();
 
 	GlobalMemory uniText;