Added SC_TECHNOLOGY_DIRECTWRITERETAIN mode.

5 files changed, 19 insertions, 5 deletions

diff --git a/doc/ScintillaDoc.html b/doc/ScintillaDoc.html
index a4dd4cc9c..e58c5cc4d 100644
--- a/doc/ScintillaDoc.html
+++ b/doc/ScintillaDoc.html
@@ -3240,8 +3240,12 @@ struct Sci_TextToFind {
      <b id="SCI_GETTECHNOLOGY">SCI_GETTECHNOLOGY</b><br />
     The technology property allows choosing between different drawing APIs and options.
     On most platforms, the only choice is <code>SC_TECHNOLOGY_DEFAULT</code> (0).
-    On Windows Vista or later, <code>SC_TECHNOLOGY_DIRECTWRITE</code> (1)
+    On Windows Vista or later, <code>SC_TECHNOLOGY_DIRECTWRITE</code> (1) or
+    <code>SC_TECHNOLOGY_DIRECTWRITERETAIN</code> (2)
     can be chosen to use the Direct2D and DirectWrite APIs for higher quality antialiased drawing.
+    <code>SC_TECHNOLOGY_DIRECTWRITERETAIN</code> differs from
+    <code>SC_TECHNOLOGY_DIRECTWRITE</code> by requesting that the frame
+    is retained after being presented which may prevent drawing failures on some cards and drivers.
     Since Direct2D buffers drawing, Scintilla's buffering can be turned off with
     <code>SCI_SETBUFFEREDDRAW(0)</code>.</p>
 
diff --git a/doc/ScintillaHistory.html b/doc/ScintillaHistory.html
index 06f8f644f..150f9f61c 100644
--- a/doc/ScintillaHistory.html
+++ b/doc/ScintillaHistory.html
@@ -497,6 +497,10 @@
 	<a href="http://sourceforge.net/p/scintilla/bugs/1639/">Bug #1639</a>.
 	</li>
 	<li>
+	On Windows another DirectWrite mode SC_TECHNOLOGY_DIRECTWRITERETAIN added
+	which may avoid drawing failures on some cards and drivers.
+	</li>
+	<li>
 	On Windows support the Visual Studio 2010+ clipboard format that indicates a line copy.
 	<a href="http://sourceforge.net/p/scintilla/bugs/1636/">Bug #1636</a>.
 	</li>
diff --git a/include/Scintilla.h b/include/Scintilla.h
index 949d42267..184bcacb7 100644
--- a/include/Scintilla.h
+++ b/include/Scintilla.h
@@ -888,6 +888,7 @@ typedef sptr_t (*SciFnDirect)(sptr_t ptr, unsigned int iMessage, uptr_t wParam,
 #define SCI_SCROLLTOEND 2629
 #define SC_TECHNOLOGY_DEFAULT 0
 #define SC_TECHNOLOGY_DIRECTWRITE 1
+#define SC_TECHNOLOGY_DIRECTWRITERETAIN 2
 #define SCI_SETTECHNOLOGY 2630
 #define SCI_GETTECHNOLOGY 2631
 #define SCI_CREATELOADER 2632
diff --git a/include/Scintilla.iface b/include/Scintilla.iface
index 75c2e643a..a30ed897f 100644
--- a/include/Scintilla.iface
+++ b/include/Scintilla.iface
@@ -2349,6 +2349,7 @@ fun void ScrollToEnd=2629(,)
 
 val SC_TECHNOLOGY_DEFAULT=0
 val SC_TECHNOLOGY_DIRECTWRITE=1
+val SC_TECHNOLOGY_DIRECTWRITERETAIN=2
 
 # Set the technology used.
 set void SetTechnology=2630(int technology,)
diff --git a/win32/ScintillaWin.cxx b/win32/ScintillaWin.cxx
index 2ff660a09..86e274178 100644
--- a/win32/ScintillaWin.cxx
+++ b/win32/ScintillaWin.cxx
@@ -457,7 +457,8 @@ void ScintillaWin::EnsureRenderTarget() {
 		D2D1_HWND_RENDER_TARGET_PROPERTIES dhrtp;
 		dhrtp.hwnd = hw;
 		dhrtp.pixelSize = size;
-		dhrtp.presentOptions = D2D1_PRESENT_OPTIONS_NONE;
+		dhrtp.presentOptions = (technology == SC_TECHNOLOGY_DIRECTWRITERETAIN) ?
+			D2D1_PRESENT_OPTIONS_RETAIN_CONTENTS : D2D1_PRESENT_OPTIONS_NONE;
 
 		D2D1_RENDER_TARGET_PROPERTIES drtp;
 		drtp.type = D2D1_RENDER_TARGET_TYPE_DEFAULT;
@@ -1402,9 +1403,11 @@ sptr_t ScintillaWin::WndProc(unsigned int iMessage, uptr_t wParam, sptr_t lParam
 			return keysAlwaysUnicode;
 
 		case SCI_SETTECHNOLOGY:
-			if ((wParam == SC_TECHNOLOGY_DEFAULT) || (wParam == SC_TECHNOLOGY_DIRECTWRITE)) {
+			if ((wParam == SC_TECHNOLOGY_DEFAULT) || 
+				(wParam == SC_TECHNOLOGY_DIRECTWRITERETAIN) ||
+				(wParam == SC_TECHNOLOGY_DIRECTWRITE)) {
 				if (technology != static_cast<int>(wParam)) {
-					if (static_cast<int>(wParam) == SC_TECHNOLOGY_DIRECTWRITE) {
+					if (static_cast<int>(wParam) > SC_TECHNOLOGY_DEFAULT) {
 #if defined(USE_D2D)
 						if (!LoadD2D())
 							// Failed to load Direct2D or DirectWrite so no effect
@@ -2960,7 +2963,8 @@ sptr_t PASCAL ScintillaWin::CTWndProc(
 						D2D1_HWND_RENDER_TARGET_PROPERTIES dhrtp;
 						dhrtp.hwnd = hWnd;
 						dhrtp.pixelSize = D2D1::SizeU(rc.right - rc.left, rc.bottom - rc.top);
-						dhrtp.presentOptions = D2D1_PRESENT_OPTIONS_NONE;
+						dhrtp.presentOptions = (sciThis->technology == SC_TECHNOLOGY_DIRECTWRITERETAIN) ?
+							D2D1_PRESENT_OPTIONS_RETAIN_CONTENTS : D2D1_PRESENT_OPTIONS_NONE;
 
 						D2D1_RENDER_TARGET_PROPERTIES drtp;
 						drtp.type = D2D1_RENDER_TARGET_TYPE_DEFAULT;