Send SCN_UPDATEUI notification when view scrolled. Satisfies feature request #3125977.

Also includes an updated field in notification so that updates of no interest can be
easily ignored.

5 files changed, 88 insertions, 14 deletions

diff --git a/doc/ScintillaDoc.html b/doc/ScintillaDoc.html
index f120e29f1..b8c2a38ae 100644
--- a/doc/ScintillaDoc.html
+++ b/doc/ScintillaDoc.html
@@ -5687,6 +5687,9 @@ struct SCNotification {
     int listType;       // SCN_USERLISTSELECTION, SCN_AUTOCSELECTION
     int x;              // SCN_DWELLSTART, SCN_DWELLEND
     int y;              // SCN_DWELLSTART, SCN_DWELLEND
+    int token;		// SCN_MODIFIED with SC_MOD_CONTAINER
+    int annotationLinesAdded;	// SC_MOD_CHANGEANNOTATION
+    int updated;	// SCN_UPDATEUI
 };
 </pre>
 
@@ -5787,13 +5790,59 @@ href="#SCI_POSITIONFROMLINE">SCI_POSITIONFROMLINE</a>(lineNumber);
     double click and the <code>line</code> field is set to the line of the double click.</p>
 
     <p><b id="SCN_UPDATEUI">SCN_UPDATEUI</b><br />
-     Either the text or styling of the document has changed or the selection range has changed. Now
-    would be a good time to update any container UI elements that depend on document or view state.
-    This was previously called <code><a class="message"
-    href="#SCN_CHECKBRACE">SCN_CHECKBRACE</a></code> because a common use is to check whether the
-    caret is next to a brace and set highlights on this brace and its corresponding matching brace.
-    This also replaces <a class="message" href="#SCN_POSCHANGED"><code>SCN_POSCHANGED</code></a>,
-    which is now deprecated.</p>
+     Either the text or styling of the document has changed or the selection range or scroll position has changed.
+     Now would be a good time to update any container UI elements that depend on document or view state.
+     The <code>updated</code> field is set to the bit set of things changed since the previous notiication.</p>
+    <table cellpadding="1" cellspacing="2" border="0" summary="Modify notification type flags">
+      <tbody>
+        <tr>
+          <th align="left">Symbol</th>
+
+          <th>Value</th>
+
+          <th align="left">Meaning</th>
+
+        </tr>
+      </tbody>
+
+      <tbody valign="top">
+        <tr>
+          <td align="left"><code>SC_UPDATE_CONTENT</code></td>
+
+          <td align="center">0x01</td>
+
+          <td>Contents, styling or markers have been changed.</td>
+
+        </tr>
+
+        <tr>
+          <td align="left"><code>SC_UPDATE_SELECTION</code></td>
+
+          <td align="center">0x02</td>
+
+          <td>Selection has been changed.</td>
+
+        </tr>
+
+        <tr>
+          <td align="left"><code>SC_UPDATE_V_SCROLL</code></td>
+
+          <td align="center">0x04</td>
+
+          <td>Scrolled vertically.</td>
+
+        </tr>
+
+        <tr>
+          <td align="left"><code>SC_UPDATE_H_SCROLL</code></td>
+
+          <td align="center">0x08</td>
+
+          <td>Scrolled horizontally.</td>
+
+        </tr>
+      </tbody>
+    </table>
 
     <p><b id="SCN_MODIFIED">SCN_MODIFIED</b><br />
      This notification is sent when the text or styling of the document changes or is about to
diff --git a/include/Scintilla.h b/include/Scintilla.h
index 0e1159b53..c0bb32332 100644
--- a/include/Scintilla.h
+++ b/include/Scintilla.h
@@ -832,6 +832,10 @@ typedef sptr_t (*SciFnDirect)(sptr_t ptr, unsigned int iMessage, uptr_t wParam,
 #define SC_MOD_CONTAINER 0x40000
 #define SC_MOD_LEXERSTATE 0x80000
 #define SC_MODEVENTMASKALL 0xFFFFF
+#define SC_UPDATE_CONTENT 0x1
+#define SC_UPDATE_SELECTION 0x2
+#define SC_UPDATE_V_SCROLL 0x4
+#define SC_UPDATE_H_SCROLL 0x8
 #define SCEN_CHANGE 768
 #define SCEN_SETFOCUS 512
 #define SCEN_KILLFOCUS 256
@@ -971,6 +975,7 @@ struct SCNotification {
 	int y;		/* SCN_DWELLSTART, SCN_DWELLEND */
 	int token;		/* SCN_MODIFIED with SC_MOD_CONTAINER */
 	int annotationLinesAdded;	/* SC_MOD_CHANGEANNOTATION */
+	int updated;	/* SCN_UPDATEUI */
 };
 
 #ifdef SCI_NAMESPACE
diff --git a/include/Scintilla.iface b/include/Scintilla.iface
index 405fc0552..1a81aca98 100644
--- a/include/Scintilla.iface
+++ b/include/Scintilla.iface
@@ -2193,6 +2193,11 @@ val SC_MOD_CONTAINER=0x40000
 val SC_MOD_LEXERSTATE=0x80000
 val SC_MODEVENTMASKALL=0xFFFFF
 
+val SC_UPDATE_CONTENT=0x1
+val SC_UPDATE_SELECTION=0x2
+val SC_UPDATE_V_SCROLL=0x4
+val SC_UPDATE_H_SCROLL=0x8
+
 # For compatibility, these go through the COMMAND notification rather than NOTIFY
 # and should have had exactly the same values as the EN_* constants.
 # Unfortunately the SETFOCUS and KILLFOCUS are flipped over from EN_*
diff --git a/src/Editor.cxx b/src/Editor.cxx
index e9a30ee72..89c67b433 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -175,7 +175,8 @@ Editor::Editor() {
 
 	lengthForEncode = -1;
 
-	needUpdateUI = true;
+	needUpdateUI = 0;
+	ContainerNeedsUpdate(SC_UPDATE_CONTENT);
 	braces[0] = invalidPosition;
 	braces[1] = invalidPosition;
 	bracesMatchStyle = STYLE_BRACEBAD;
@@ -434,7 +435,10 @@ int Editor::LineFromLocation(Point pt) {
 }
 
 void Editor::SetTopLine(int topLineNew) {
-	topLine = topLineNew;
+	if (topLine != topLineNew) {
+		topLine = topLineNew;
+		ContainerNeedsUpdate(SC_UPDATE_V_SCROLL);
+	}
 	posTopLine = pdoc->LineStart(cs.DocFromDisplay(topLine));
 }
 
@@ -741,7 +745,7 @@ void Editor::InvalidateSelection(SelectionRange newMain, bool invalidateWholeSel
 			lastAffected = Platform::Maximum(lastAffected, sel.Range(r).anchor.Position());
 		}
 	}
-	needUpdateUI = true;
+	ContainerNeedsUpdate(SC_UPDATE_SELECTION);
 	InvalidateRange(firstAffected, lastAffected);
 }
 
@@ -982,6 +986,7 @@ void Editor::HorizontalScrollTo(int xPos) {
 		xPos = 0;
 	if ((wrapState == eWrapNone) && (xOffset != xPos)) {
 		xOffset = xPos;
+		ContainerNeedsUpdate(SC_UPDATE_H_SCROLL);
 		SetHorizontalScrollPos();
 		RedrawRect(GetClientRectangle());
 	}
@@ -1291,6 +1296,7 @@ void Editor::SetXYScroll(XYScrollPosition newXY) {
 		}
 		if (newXY.xOffset != xOffset) {
 			xOffset = newXY.xOffset;
+			ContainerNeedsUpdate(SC_UPDATE_H_SCROLL);
 			if (newXY.xOffset > 0) {
 				PRectangle rcText = GetTextRectangle();
 				if (horizontalScrollBarVisible &&
@@ -3307,7 +3313,7 @@ void Editor::Paint(Surface *surfaceWindow, PRectangle rcArea) {
 		surfaceWindow->SetPalette(&palTemp, true);
 
 		NotifyUpdateUI();
-		needUpdateUI = false;
+		needUpdateUI = 0;
 
 		RefreshStyleData();
 		RefreshPixMaps(surfaceWindow);
@@ -4213,6 +4219,7 @@ void Editor::NotifyHotSpotReleaseClick(int position, bool shift, bool ctrl, bool
 void Editor::NotifyUpdateUI() {
 	SCNotification scn = {0};
 	scn.nmhdr.code = SCN_UPDATEUI;
+	scn.updated = needUpdateUI;
 	NotifyParent(scn);
 }
 
@@ -4329,7 +4336,7 @@ static inline int MovePositionForDeletion(int position, int startDeletion, int l
 }
 
 void Editor::NotifyModified(Document *, DocModification mh, void *) {
-	needUpdateUI = true;
+	ContainerNeedsUpdate(SC_UPDATE_CONTENT);
 	if (paintState == painting) {
 		CheckForChangeOutsidePaint(Range(mh.position, mh.position + mh.length));
 	}
@@ -4611,6 +4618,11 @@ void Editor::NotifyMacroRecord(unsigned int iMessage, uptr_t wParam, sptr_t lPar
 	NotifyParent(scn);
 }
 
+// Something has changed that the container should know about
+void Editor::ContainerNeedsUpdate(int flags) {
+	needUpdateUI |= flags;
+}
+
 /**
  * Force scroll and keep position relative to top of window.
  *
@@ -6338,7 +6350,7 @@ void Editor::IdleStyling() {
 
 	if (needUpdateUI) {
 		NotifyUpdateUI();
-		needUpdateUI = false;
+		needUpdateUI = 0;
 	}
 	styleNeeded.Reset();
 }
@@ -6995,6 +7007,7 @@ sptr_t Editor::WndProc(unsigned int iMessage, uptr_t wParam, sptr_t lParam) {
 
 	case SCI_SETXOFFSET:
 		xOffset = wParam;
+		ContainerNeedsUpdate(SC_UPDATE_H_SCROLL);
 		SetHorizontalScrollPos();
 		Redraw();
 		break;
@@ -7459,6 +7472,7 @@ sptr_t Editor::WndProc(unsigned int iMessage, uptr_t wParam, sptr_t lParam) {
 			break;
 		}
 		xOffset = 0;
+		ContainerNeedsUpdate(SC_UPDATE_H_SCROLL);
 		InvalidateStyleRedraw();
 		ReconfigureScrollBars();
 		break;
diff --git a/src/Editor.h b/src/Editor.h
index 288addee0..a618e1e40 100644
--- a/src/Editor.h
+++ b/src/Editor.h
@@ -208,7 +208,7 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 	int posTopLine;
 	int lengthForEncode;
 
-	bool needUpdateUI;
+	int needUpdateUI;
 	Position braces[2];
 	int bracesMatchStyle;
 	int highlightGuideColumn;
@@ -438,6 +438,7 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 	void NotifyErrorOccurred(Document *doc, void *userData, int status);
 	void NotifyMacroRecord(unsigned int iMessage, uptr_t wParam, sptr_t lParam);
 
+	void ContainerNeedsUpdate(int flags);
 	void PageMove(int direction, Selection::selTypes sel=Selection::noSel, bool stuttered = false);
 	enum { cmSame, cmUpper, cmLower } caseMap;
 	virtual std::string CaseMapString(const std::string &s, int caseMapping);