From b863e024b9bcdc78a11e2acbc93cc2e1ef79ba2e Mon Sep 17 00:00:00 2001
From: Zufu Liu <unknown>
Date: Fri, 25 Jun 2021 19:47:51 +1000
Subject: Feature [feature-requests:#1400] Set buffering when technology set.

---
 doc/ScintillaDoc.html     | 12 +++++++++---
 doc/ScintillaHistory.html | 13 +++++++++++++
 test/simpleTests.py       | 26 ++++++++++++++++++++++++++
 win32/ScintillaWin.cxx    |  1 +
 4 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/doc/ScintillaDoc.html b/doc/ScintillaDoc.html
index 9fbb50350..50409c0af 100644
--- a/doc/ScintillaDoc.html
+++ b/doc/ScintillaDoc.html
@@ -128,7 +128,7 @@
 
     <h1>Scintilla Documentation</h1>
 
-    <p>Last edited 17 June 2021 NH</p>
+    <p>Last edited 25 June 2021 NH</p>
 
     <p style="background:#90F0C0">Scintilla 5 has moved the lexers from Scintilla into a new
     <a href="Lexilla.html">Lexilla</a> project.<br />
@@ -4511,8 +4511,14 @@ struct Sci_TextToFind {
     is retained after being presented which may prevent drawing failures on some cards and drivers.
     <code>SC_TECHNOLOGY_DIRECTWRITEDC</code> differs from
     <code>SC_TECHNOLOGY_DIRECTWRITE</code> by using DirectWrite to draw into a GDI DC.
-    Since Direct2D buffers drawing, Scintilla's buffering can be turned off with
-    <code>SCI_SETBUFFEREDDRAW(0)</code>.
+    </p>
+    <p>
+    On Win32, buffered drawing is set to a reasonable value for the technology: on for GDI and off for Direct2D
+    as Direct2D performs its own buffering.
+    This can be changed after setting technology with
+    <a class="seealso" href="#SCI_SETBUFFEREDDRAW">SCI_SETBUFFEREDDRAW</a>.
+    </p>
+    <p>
     When using DirectWrite, you can use
     <a class="message" href="#SCI_SETFONTLOCALE"><code>SCI_SETFONTLOCALE</code></a>
     to set an appropriate font locale to draw text with expected language-dependent glyphs.
diff --git a/doc/ScintillaHistory.html b/doc/ScintillaHistory.html
index 634a7ff50..542fd4eb9 100644
--- a/doc/ScintillaHistory.html
+++ b/doc/ScintillaHistory.html
@@ -564,6 +564,19 @@
     </tr>
     </table>
     <h2>Releases</h2>
+    <h3>
+       <a href="https://www.scintilla.org/scintilla511.zip">Release 5.1.1</a>
+    </h3>
+    <ul>
+	<li>
+	Released 23 June 2021.
+	</li>
+	<li>
+	On Win32, when technology is changed, buffering is set to a reasonable value for the technology:
+	on for GDI and off for Direct2D as Direct2D performs its own buffering.
+	<a href="https://sourceforge.net/p/scintilla/feature-requests/1400/">Feature #1400</a>.
+	</li>
+    </ul>
     <h3>
        <a href="https://www.scintilla.org/scintilla510.zip">Release 5.1.0</a>
     </h3>
diff --git a/test/simpleTests.py b/test/simpleTests.py
index 2d8b25e68..dca1e24c4 100644
--- a/test/simpleTests.py
+++ b/test/simpleTests.py
@@ -1854,6 +1854,32 @@ class TestModalSelection(unittest.TestCase):
 		self.assertEquals(self.ed.GetSelectionNAnchor(0), 0)
 		self.ed.ClearSelections()
 
+class TestTechnology(unittest.TestCase):
+	""" These tests are just to ensure that the calls set and retrieve values.
+	They assume running on a Direct2D compatible version of Windows.
+	They do not check visual appearance.
+	"""
+	def setUp(self):
+		self.xite = Xite.xiteFrame
+		self.ed = self.xite.ed
+		self.ed.ClearAll()
+		self.ed.EmptyUndoBuffer()
+
+	def tearDown(self):
+		self.ed.ClearAll()
+		self.ed.EmptyUndoBuffer()
+
+	def testTechnologyAndBufferedDraw(self):
+		self.ed.Technology = self.ed.SC_TECHNOLOGY_DEFAULT
+		self.assertEquals(self.ed.GetTechnology(), self.ed.SC_TECHNOLOGY_DEFAULT)
+		if sys.platform == "win32":
+			self.ed.Technology = self.ed.SC_TECHNOLOGY_DIRECTWRITE
+			self.assertEquals(self.ed.GetTechnology(), self.ed.SC_TECHNOLOGY_DIRECTWRITE)
+			self.assertEquals(self.ed.BufferedDraw, False)
+			self.ed.Technology = self.ed.SC_TECHNOLOGY_DEFAULT
+			self.assertEquals(self.ed.GetTechnology(), self.ed.SC_TECHNOLOGY_DEFAULT)
+			self.assertEquals(self.ed.BufferedDraw, True)
+
 class TestStyleAttributes(unittest.TestCase):
 	""" These tests are just to ensure that the calls set and retrieve values.
 	They do not check the visual appearance of the style attributes.
diff --git a/win32/ScintillaWin.cxx b/win32/ScintillaWin.cxx
index 0af4a6d65..64ca03cfa 100644
--- a/win32/ScintillaWin.cxx
+++ b/win32/ScintillaWin.cxx
@@ -1832,6 +1832,7 @@ sptr_t ScintillaWin::SciMessage(Message iMessage, uptr_t wParam, sptr_t lParam)
 				}
 				DropRenderTarget();
 				technology = technologyNew;
+				view.bufferedDraw = technologyNew == Technology::Default;
 				// Invalidate all cached information including layout.
 				DropGraphics();
 				InvalidateStyleRedraw();
-- 
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