Feature request #3064696 SCI_VERTICALCENTRECARET: center current line in window.

4 files changed, 23 insertions, 3 deletions

diff --git a/include/Scintilla.h b/include/Scintilla.h
index 331216979..0e1159b53 100644
--- a/include/Scintilla.h
+++ b/include/Scintilla.h
@@ -787,6 +787,7 @@ typedef sptr_t (*SciFnDirect)(sptr_t ptr, unsigned int iMessage, uptr_t wParam,
 #define SCI_SWAPMAINANCHORCARET 2607
 #define SCI_CHANGELEXERSTATE 2617
 #define SCI_CONTRACTEDFOLDNEXT 2618
+#define SCI_VERTICALCENTRECARET 2619
 #define SCI_STARTRECORD 3001
 #define SCI_STOPRECORD 3002
 #define SCI_SETLEXER 4001
diff --git a/include/Scintilla.iface b/include/Scintilla.iface
index a8ef722a0..61031398c 100644
--- a/include/Scintilla.iface
+++ b/include/Scintilla.iface
@@ -259,7 +259,7 @@ val SC_MARK_CIRCLEPLUSCONNECTED=19
 val SC_MARK_CIRCLEMINUS=20
 val SC_MARK_CIRCLEMINUSCONNECTED=21
 
-# Invisible mark that only sets the line background color.
+# Invisible mark that only sets the line background colour.
 val SC_MARK_BACKGROUND=22
 val SC_MARK_DOTDOTDOT=23
 val SC_MARK_ARROWS=24
@@ -2095,6 +2095,9 @@ fun int ChangeLexerState=2617(position start, position end)
 # Return -1 when no more lines.
 fun int ContractedFoldNext=2618(int lineStart,)
 
+# Centre current line in window.
+fun void VerticalCentreCaret=2619(,)
+
 # Start notifying the container of all key presses and commands.
 fun void StartRecord=3001(,)
 
diff --git a/src/Editor.cxx b/src/Editor.cxx
index 681cb12cd..c03ff8f31 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -995,6 +995,16 @@ void Editor::HorizontalScrollTo(int xPos) {
 	}
 }
 
+void Editor::VerticalCentreCaret() {
+	int lineDoc = pdoc->LineFromPosition(sel.IsRectangular() ? sel.Rectangular().caret.Position() : sel.MainCaret());
+	int lineDisplay = cs.DisplayFromDoc(lineDoc);
+	int newTop = lineDisplay - (LinesOnScreen() / 2);
+	if (topLine != newTop) {
+		SetTopLine(newTop > 0 ? newTop : 0);
+		RedrawRect(GetClientRectangle());
+	}
+}
+
 void Editor::MoveCaretInsideView(bool ensureVisible) {
 	PRectangle rcClient = GetTextRectangle();
 	Point pt = PointMainCaret();
@@ -4589,6 +4599,7 @@ void Editor::NotifyMacroRecord(unsigned int iMessage, uptr_t wParam, sptr_t lPar
 	case SCI_PAGEDOWNRECTEXTEND:
 	case SCI_SELECTIONDUPLICATE:
 	case SCI_COPYALLOWLINE:
+	case SCI_VERTICALCENTRECARET:
 		break;
 
 		// Filter out all others like display changes. Also, newlines are redundant
@@ -6319,7 +6330,7 @@ void Editor::StyleToPositionInView(Position pos) {
 	int styleAtEnd = pdoc->StyleAt(pos-1);
 	pdoc->EnsureStyledTo(pos);
 	if ((endWindow > pos) && (styleAtEnd != pdoc->StyleAt(pos-1))) {
-		// Style at end of line changed so is multi-line change like starting a comment 
+		// Style at end of line changed so is multi-line change like starting a comment
 		// so require rest of window to be styled.
 		pdoc->EnsureStyledTo(endWindow);
 	}
@@ -6794,6 +6805,10 @@ sptr_t Editor::WndProc(unsigned int iMessage, uptr_t wParam, sptr_t lParam) {
 		CopyAllowLine();
 		break;
 
+	case SCI_VERTICALCENTRECARET:
+		VerticalCentreCaret();
+		break;
+
 	case SCI_COPYRANGE:
 		CopyRangeToClipboard(wParam, lParam);
 		break;
diff --git a/src/Editor.h b/src/Editor.h
index 17683c63a..50948e2e3 100644
--- a/src/Editor.h
+++ b/src/Editor.h
@@ -219,7 +219,7 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 	PRectangle rcPaint;
 	bool paintingAllText;
 	StyleNeeded styleNeeded;
-	
+
 	int modEventMask;
 
 	SelectionText drag;
@@ -328,6 +328,7 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 	void ScrollTo(int line, bool moveThumb=true);
 	virtual void ScrollText(int linesToMove);
 	void HorizontalScrollTo(int xPos);
+	void VerticalCentreCaret();
 	void MoveCaretInsideView(bool ensureVisible=true);
 	int DisplayFromPosition(int pos);