Bug [#1910]. Accessibility support may be queried and, on GTK+, disabled.

10 files changed, 129 insertions, 13 deletions

diff --git a/cocoa/ScintillaCocoa.mm b/cocoa/ScintillaCocoa.mm
index 1caed47da..cc5ee0fc7 100644
--- a/cocoa/ScintillaCocoa.mm
+++ b/cocoa/ScintillaCocoa.mm
@@ -906,6 +906,9 @@ sptr_t ScintillaCocoa::WndProc(unsigned int iMessage, uptr_t wParam, sptr_t lPar
           return r;
         }
 
+      case SCI_GETACCESSIBILITY:
+          return SC_ACCESSIBILITY_ENABLED;
+
       default:
         sptr_t r = ScintillaBase::WndProc(iMessage, wParam, lParam);
 
diff --git a/doc/ScintillaDoc.html b/doc/ScintillaDoc.html
index a29bfe617..631b38eb8 100644
--- a/doc/ScintillaDoc.html
+++ b/doc/ScintillaDoc.html
@@ -367,16 +367,16 @@
         <tr>
           <td>&cir; <a class="toc" href="#LongLines">Long lines</a></td>
 
-          <td>&cir; <a class="toc" href="#Lexer">Lexer</a></td>
+          <td>&cir; <a class="toc" href="#Accessibility">Accessibility</a></td>
 
-          <td>&cir; <a class="toc" href="#LexerObjects">Lexer objects</a></td>
+          <td>&cir; <a class="toc" href="#Lexer">Lexer</a></td>
 
         </tr>
 
         <tr>
-          <td>&cir; <a class="toc" href="#Notifications">Notifications</a></td>
+          <td>&cir; <a class="toc" href="#LexerObjects">Lexer objects</a></td>
 
-          <td>&cir; <a class="toc" href="#Accessibility">Accessibility</a></td>
+          <td>&cir; <a class="toc" href="#Notifications">Notifications</a></td>
 
           <td>&cir; <a class="toc" href="#Images">Images</a></td>
 
@@ -6511,6 +6511,60 @@ sptr_t CallScintilla(unsigned int iMessage, uptr_t wParam, sptr_t lParam){
     of a space character in <code>STYLE_DEFAULT</code>. All the edges can be cleared with
     <code>SCI_MULTIEDGECLEARALL</code>.</p>
 
+    <h2 id="Accessibility">Accessibility</h2>
+
+    <p>Scintilla supports some platform accessibility features.
+    This support differs between platforms.
+    On GTK+ and Cocoa the platform accessibility APIs are implemented sufficiently to
+    make screen readers work.
+    On Win32, the system caret is manipulated to help screen readers.
+    </p>
+
+    <code><a class="message" href="#SCI_SETACCESSIBILITY">SCI_SETACCESSIBILITY(int accessibility)</a><br />
+     <a class="message" href="#SCI_GETACCESSIBILITY">SCI_GETACCESSIBILITY &rarr; int</a><br />
+    </code>
+
+    <p><b id="SCI_SETACCESSIBILITY">SCI_SETACCESSIBILITY(int accessibility)</b><br />
+     <b id="SCI_GETACCESSIBILITY">SCI_GETACCESSIBILITY &rarr; int</b><br />
+     These messages may enable or disable accessibility and report its current status.</p>
+
+    <p>On most platforms, accessibility is either implemented or not implemented and this can be
+    discovered with <code>SCI_GETACCESSIBILITY</code> with
+    <code>SCI_SETACCESSIBILITY</code> performing no action.
+    On GTK+, there are storage and performance costs to accessibility, so it can be disabled
+    by calling <code>SCI_SETACCESSIBILITY</code>.
+    </p>
+ 
+    <table class="standard" summary="Accessibility status">
+      <tbody>
+        <tr>
+          <th align="left">Symbol</th>
+
+          <th>Value</th>
+
+          <th align="left">Accessibility status</th>
+        </tr>
+      </tbody>
+
+      <tbody valign="top">
+        <tr>
+          <td align="left"><code>SC_ACCESSIBILITY_DISABLED</code></td>
+
+          <td align="center">0</td>
+
+          <td>Accessibility is disabled.</td>
+        </tr>
+
+        <tr>
+          <td align="left"><code>SC_ACCESSIBILITY_ENABLED</code></td>
+
+          <td align="center">1</td>
+
+          <td>Accessibility is enabled.</td>
+        </tr>
+      </tbody>
+    </table>
+   
     <h2 id="Lexer">Lexer</h2>
 
     <p>If you define the symbol <code>SCI_LEXER</code> when building Scintilla, (this is sometimes
@@ -7891,15 +7945,6 @@ for line = lineStart to lineEnd do SCI_ENSUREVISIBLE(line) next
      <a class="jump" href="#SCN_AUTOCSELECTION">SCN_AUTOCSELECTION</a></code>
      notification.</p>
 
-    <h2 id="Accessibility">Accessibility</h2>
-
-    <p>Scintilla supports some platform accessibility features.
-    This support differs between platforms.
-    On GTK+ and Cocoa the platform accessibility APIs are implemented sufficiently to
-    make screen readers work.
-    On Win32, the system caret is manipulated to help screen readers.
-    </p>
-
     <h2 id="Images">Images</h2>
 
     <p>Two formats are supported for images used in margin markers and autocompletion lists, RGBA and XPM.</p>
diff --git a/doc/ScintillaHistory.html b/doc/ScintillaHistory.html
index a8bad7678..290ac3927 100644
--- a/doc/ScintillaHistory.html
+++ b/doc/ScintillaHistory.html
@@ -527,6 +527,10 @@
 	Released 19 February 2017.
 	</li>
 	<li>
+	Accessibility support may be queried with SCI_GETACCESSIBILITY.
+	On GTK+, accessibility may be disabled by calling SCI_SETACCESSIBILITY.
+	</li>
+	<li>
 	Lexer added for "indent" language which is styled as plain text but folded by indentation level.
 	</li>
 	<li>
diff --git a/gtk/ScintillaGTK.cxx b/gtk/ScintillaGTK.cxx
index 35622bc02..46a4b488f 100644
--- a/gtk/ScintillaGTK.cxx
+++ b/gtk/ScintillaGTK.cxx
@@ -175,6 +175,7 @@ ScintillaGTK::ScintillaGTK(_ScintillaObject *sci_) :
 		rgnUpdate(0),
 		repaintFullWindow(false),
 		styleIdleID(0),
+		accessibilityEnabled(SC_ACCESSIBILITY_ENABLED),
 		accessible(0) {
 	sci = sci_;
 	wMain = GTK_WIDGET(sci);
@@ -875,6 +876,19 @@ sptr_t ScintillaGTK::WndProc(unsigned int iMessage, uptr_t wParam, sptr_t lParam
 			return ret;
 		}
 
+		case SCI_GETACCESSIBILITY:
+			return accessibilityEnabled;
+
+		case SCI_SETACCESSIBILITY:
+			accessibilityEnabled = wParam;
+			if (accessible) {
+				ScintillaGTKAccessible *sciAccessible = ScintillaGTKAccessible::FromAccessible(accessible);
+				if (sciAccessible) {
+					sciAccessible->SetAccessibility();
+				}
+			}
+			break;
+
 		default:
 			return ScintillaBase::WndProc(iMessage, wParam, lParam);
 		}
diff --git a/gtk/ScintillaGTK.h b/gtk/ScintillaGTK.h
index 6f69661f2..4ee55a6c8 100644
--- a/gtk/ScintillaGTK.h
+++ b/gtk/ScintillaGTK.h
@@ -68,6 +68,7 @@ class ScintillaGTK : public ScintillaBase {
 	bool repaintFullWindow;
 
 	guint styleIdleID;
+	int accessibilityEnabled;
 	AtkObject *accessible;
 
 	// Private so ScintillaGTK objects can not be copied
diff --git a/gtk/ScintillaGTKAccessible.cxx b/gtk/ScintillaGTKAccessible.cxx
index 4fcfcda99..001f2703f 100644
--- a/gtk/ScintillaGTKAccessible.cxx
+++ b/gtk/ScintillaGTKAccessible.cxx
@@ -788,6 +788,10 @@ void ScintillaGTKAccessible::AtkEditableTextIface::init(::AtkEditableTextIface *
 	//~ iface->set_run_attributes = SetRunAttributes;
 }
 
+bool ScintillaGTKAccessible::Enabled() const {
+	return sci->accessibilityEnabled == SC_ACCESSIBILITY_ENABLED;
+}
+
 // Callbacks
 
 void ScintillaGTKAccessible::UpdateCursor() {
@@ -820,6 +824,10 @@ void ScintillaGTKAccessible::UpdateCursor() {
 }
 
 void ScintillaGTKAccessible::ChangeDocument(Document *oldDoc, Document *newDoc) {
+	if (!Enabled()) {
+		return;
+	}
+
 	if (oldDoc == newDoc) {
 		return;
 	}
@@ -854,7 +862,15 @@ void ScintillaGTKAccessible::NotifyReadOnly() {
 #endif
 }
 
+void ScintillaGTKAccessible::SetAccessibility() {
+	// Called by ScintillaGTK when application has enabled or disabled accessibility
+	character_offsets.resize(0);
+	character_offsets.push_back(0);
+}
+
 void ScintillaGTKAccessible::Notify(GtkWidget *, gint, SCNotification *nt) {
+	if (!Enabled())
+		return;
 	switch (nt->nmhdr.code) {
 		case SCN_MODIFIED: {
 			if (nt->modificationType & (SC_MOD_INSERTTEXT | SC_MOD_DELETETEXT)) {
@@ -864,6 +880,13 @@ void ScintillaGTKAccessible::Notify(GtkWidget *, gint, SCNotification *nt) {
 					character_offsets.resize(line + 1);
 				}
 			}
+			if (nt->modificationType & (SC_MOD_INSERTTEXT | SC_MOD_DELETETEXT)) {
+				// invalidate character offset cache if applicable
+				const Position line = sci->pdoc->LineFromPosition(nt->position);
+				if (character_offsets.size() > static_cast<size_t>(line + 1)) {
+					character_offsets.resize(line + 1);
+				}
+			}
 			if (nt->modificationType & SC_MOD_INSERTTEXT) {
 				int startChar = CharacterOffsetFromByteOffset(nt->position);
 				int lengthChar = sci->pdoc->CountCharacters(nt->position, nt->position + nt->length);
diff --git a/gtk/ScintillaGTKAccessible.h b/gtk/ScintillaGTKAccessible.h
index 88256e0ca..1905c0619 100644
--- a/gtk/ScintillaGTKAccessible.h
+++ b/gtk/ScintillaGTKAccessible.h
@@ -23,12 +23,16 @@ private:
 	// cache holding character offset for each line start, see CharacterOffsetFromByteOffset()
 	std::vector<Position> character_offsets;
 
+	// cache holding character offset for each line start, see CharacterOffsetFromByteOffset()
+	std::vector<Position> character_offsets;
+
 	// cached length of the deletion, in characters (see Notify())
 	int deletionLengthChar;
 	// local state for comparing
 	Position old_pos;
 	std::vector<SelectionRange> old_sels;
 
+	bool Enabled() const;
 	void UpdateCursor();
 	void Notify(GtkWidget *widget, gint code, SCNotification *nt);
 	static void SciNotify(GtkWidget *widget, gint code, SCNotification *nt, gpointer data) {
@@ -136,6 +140,7 @@ public:
 	// So ScintillaGTK can notify us
 	void ChangeDocument(Document *oldDoc, Document *newDoc);
 	void NotifyReadOnly();
+	void SetAccessibility();
 
 	// Helper GtkWidget methods
 	static AtkObject *WidgetGetAccessibleImpl(GtkWidget *widget, AtkObject **cache, gpointer widget_parent_class);
diff --git a/include/Scintilla.h b/include/Scintilla.h
index 6a36d24f4..b997c0a5b 100644
--- a/include/Scintilla.h
+++ b/include/Scintilla.h
@@ -593,6 +593,10 @@ typedef sptr_t (*SciFnDirect)(sptr_t ptr, unsigned int iMessage, uptr_t wParam,
 #define SCI_LINESSPLIT 2289
 #define SCI_SETFOLDMARGINCOLOUR 2290
 #define SCI_SETFOLDMARGINHICOLOUR 2291
+#define SC_ACCESSIBILITY_DISABLED 0
+#define SC_ACCESSIBILITY_ENABLED 1
+#define SCI_SETACCESSIBILITY 2702
+#define SCI_GETACCESSIBILITY 2703
 #define SCI_LINEDOWN 2300
 #define SCI_LINEDOWNEXTEND 2301
 #define SCI_LINEUP 2302
diff --git a/include/Scintilla.iface b/include/Scintilla.iface
index 4c964e3fd..5aa5f8ee3 100644
--- a/include/Scintilla.iface
+++ b/include/Scintilla.iface
@@ -1476,6 +1476,16 @@ fun void SetFoldMarginColour=2290(bool useSetting, colour back)
 # Set the other colour used as a chequerboard pattern in the fold margin
 fun void SetFoldMarginHiColour=2291(bool useSetting, colour fore)
 
+enu Accessibility=SC_ACCESSIBILITY_
+val SC_ACCESSIBILITY_DISABLED=0
+val SC_ACCESSIBILITY_ENABLED=1
+
+# Enable or disable accessibility.
+set void SetAccessibility=2702(int accessibility,)
+
+# Report accessibility status.
+get int GetAccessibility=2703(,)
+
 ## New messages go here
 
 ## Start of key messages
diff --git a/src/Editor.cxx b/src/Editor.cxx
index e5fbc69be..35bbc10fe 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -7554,6 +7554,13 @@ sptr_t Editor::WndProc(unsigned int iMessage, uptr_t wParam, sptr_t lParam) {
 		std::vector<EdgeProperties>().swap(vs.theMultiEdge); // Free vector and memory, C++03 compatible
 		InvalidateStyleRedraw();
 		break;
+	
+	case SCI_GETACCESSIBILITY:
+		return SC_ACCESSIBILITY_DISABLED;
+
+	case SCI_SETACCESSIBILITY:
+		// May be implemented by platform code.
+		break;
 
 	case SCI_GETDOCPOINTER:
 		return reinterpret_cast<sptr_t>(pdoc);