Add Supports::ThreadSafeMeasureWidths for platforms to indicate if they support

concurrent calls to MeasureWidths.

7 files changed, 23 insertions, 3 deletions

diff --git a/cocoa/PlatCocoa.mm b/cocoa/PlatCocoa.mm
index 239884341..bec420a66 100644
--- a/cocoa/PlatCocoa.mm
+++ b/cocoa/PlatCocoa.mm
@@ -348,6 +348,7 @@ const Supports SupportsCocoa[] = {
 	Supports::FractionalStrokeWidth,
 	Supports::TranslucentStroke,
 	Supports::PixelModification,
+	Supports::ThreadSafeMeasureWidths,
 };
 
 }
diff --git a/doc/ScintillaDoc.html b/doc/ScintillaDoc.html
index e54059624..58e8da944 100644
--- a/doc/ScintillaDoc.html
+++ b/doc/ScintillaDoc.html
@@ -50,6 +50,7 @@
 	table.standard tr:nth-child(even) {background: #F0F0F0}
 	table.standard td {
 		padding: 1px 5px 1px 5px;
+		vertical-align:top;
 	}
 	tr.section {
 		border-top:1px solid #808080;
@@ -128,7 +129,7 @@
 
     <h1>Scintilla Documentation</h1>
 
-    <p>Last edited 12 November 2021 NH</p>
+    <p>Last edited 2 February 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 />
@@ -4691,13 +4692,15 @@ struct Sci_TextToFind {
         <tr>
           <td><code>SC_SUPPORTS_LINE_DRAWS_FINAL</code></td>
           <td>0</td>
-          <td>Whether drawing a line draws its final position. Only false on Win32 GDI.</td>
+          <td>Whether drawing a line draws its final position.<br />
+          Only false on Win32 GDI.</div></td>
         </tr>
 
         <tr>
           <td><code>SC_SUPPORTS_PIXEL_DIVISIONS</code></td>
           <td>1</td>
-          <td>Are logical pixels larger than physical pixels? Currently only true for macOS Cocoa with 'retina' displays.
+          <td>Are logical pixels larger than physical pixels?<br />
+          Currently only true for macOS Cocoa with 'retina' displays.<br />
           When true, creating pixmaps at twice the resolution can produce clearer output with less blur.</td>
         </tr>
 
@@ -4719,6 +4722,14 @@ struct Sci_TextToFind {
           <td>Can individual pixels be modified? This is false for character cell platforms like curses.</td>
         </tr>
 
+        <tr>
+          <td><code>SC_SUPPORTS_THREAD_SAFE_MEASURE_WIDTHS</code></td>
+          <td>5</td>
+          <td>Can text measurement be safely performed concurrently on multiple threads?<br />
+          Currently only true for macOS Cocoa, DirectWrite on Win32, and GTK on X or Wayland.
+          </td>
+        </tr>
+
       </tbody>
     </table>
 
diff --git a/gtk/PlatGTK.cxx b/gtk/PlatGTK.cxx
index 53ee57300..859589bec 100755
--- a/gtk/PlatGTK.cxx
+++ b/gtk/PlatGTK.cxx
@@ -215,6 +215,10 @@ const Supports SupportsGTK[] = {
 	Supports::FractionalStrokeWidth,
 	Supports::TranslucentStroke,
 	Supports::PixelModification,
+#if !defined(PLAT_GTK_WIN32) && !defined(PLAT_GTK_MACOSX)
+	// Pango is not thread-safe on Win32 or macOS
+	Supports::ThreadSafeMeasureWidths,
+#endif
 };
 
 }
diff --git a/include/Scintilla.h b/include/Scintilla.h
index b46e886b6..7ab0e3560 100644
--- a/include/Scintilla.h
+++ b/include/Scintilla.h
@@ -1101,6 +1101,7 @@ typedef sptr_t (*SciFnDirectStatus)(sptr_t ptr, unsigned int iMessage, uptr_t wP
 #define SC_SUPPORTS_FRACTIONAL_STROKE_WIDTH 2
 #define SC_SUPPORTS_TRANSLUCENT_STROKE 3
 #define SC_SUPPORTS_PIXEL_MODIFICATION 4
+#define SC_SUPPORTS_THREAD_SAFE_MEASURE_WIDTHS 5
 #define SCI_SUPPORTSFEATURE 2750
 #define SC_LINECHARACTERINDEX_NONE 0
 #define SC_LINECHARACTERINDEX_UTF32 1
diff --git a/include/Scintilla.iface b/include/Scintilla.iface
index f2ef2d33e..a98a310ab 100644
--- a/include/Scintilla.iface
+++ b/include/Scintilla.iface
@@ -3040,6 +3040,7 @@ val SC_SUPPORTS_PIXEL_DIVISIONS=1
 val SC_SUPPORTS_FRACTIONAL_STROKE_WIDTH=2
 val SC_SUPPORTS_TRANSLUCENT_STROKE=3
 val SC_SUPPORTS_PIXEL_MODIFICATION=4
+val SC_SUPPORTS_THREAD_SAFE_MEASURE_WIDTHS=5
 
 # Get whether a feature is supported
 get bool SupportsFeature=2750(Supports feature,)
diff --git a/include/ScintillaTypes.h b/include/ScintillaTypes.h
index 917878474..fe4b06032 100644
--- a/include/ScintillaTypes.h
+++ b/include/ScintillaTypes.h
@@ -507,6 +507,7 @@ enum class Supports {
 	FractionalStrokeWidth = 2,
 	TranslucentStroke = 3,
 	PixelModification = 4,
+	ThreadSafeMeasureWidths = 5,
 };
 
 enum class LineCharacterIndexType {
diff --git a/win32/PlatWin.cxx b/win32/PlatWin.cxx
index 645decb35..9a41614cd 100644
--- a/win32/PlatWin.cxx
+++ b/win32/PlatWin.cxx
@@ -1282,6 +1282,7 @@ constexpr Supports SupportsD2D[] = {
 	Supports::FractionalStrokeWidth,
 	Supports::TranslucentStroke,
 	Supports::PixelModification,
+	Supports::ThreadSafeMeasureWidths,
 };
 
 constexpr D2D_COLOR_F ColorFromColourAlpha(ColourRGBA colour) noexcept {