From b443d58497d6d2cfce83c3882ff0cf0ce45914d1 Mon Sep 17 00:00:00 2001
From: Neil Hodgson <nyamatongwe@gmail.com>
Date: Thu, 7 Apr 2022 13:08:52 +1000
Subject: Bug [#2322] Fix partial updates and non-responsive scroll bars on
 Xorg. Also fixes bugs [#2196] and [#2312].

---
 gtk/ScintillaGTK.cxx | 27 +++++++++++++++++++++++++++
 gtk/ScintillaGTK.h   |  2 ++
 2 files changed, 29 insertions(+)

(limited to 'gtk')

diff --git a/gtk/ScintillaGTK.cxx b/gtk/ScintillaGTK.cxx
index a1ac3adf8..877b4763a 100755
--- a/gtk/ScintillaGTK.cxx
+++ b/gtk/ScintillaGTK.cxx
@@ -259,6 +259,10 @@ ScintillaGTK::~ScintillaGTK() {
 		g_source_remove(styleIdleID);
 		styleIdleID = 0;
 	}
+	if (scrollBarIdleID) {
+		g_source_remove(scrollBarIdleID);
+		scrollBarIdleID = 0;
+	}
 	ClearPrimarySelection();
 	wPreedit.Destroy();
 	if (settingsHandlerId) {
@@ -1109,6 +1113,7 @@ bool ScintillaGTK::ModifyScrollBars(Sci::Line nMax, Sci::Line nPage) {
 #if !GTK_CHECK_VERSION(3,18,0)
 		gtk_adjustment_changed(GTK_ADJUSTMENT(adjustmentv));
 #endif
+		gtk_adjustment_set_value(GTK_ADJUSTMENT(adjustmentv), static_cast<gdouble>(topLine));
 		modified = true;
 	}
 
@@ -1130,6 +1135,7 @@ bool ScintillaGTK::ModifyScrollBars(Sci::Line nMax, Sci::Line nPage) {
 #if !GTK_CHECK_VERSION(3,18,0)
 		gtk_adjustment_changed(GTK_ADJUSTMENT(adjustmenth));
 #endif
+		gtk_adjustment_set_value(GTK_ADJUSTMENT(adjustmenth), xOffset);
 		modified = true;
 	}
 	if (modified && (paintState == PaintState::painting)) {
@@ -1144,6 +1150,27 @@ void ScintillaGTK::ReconfigureScrollBars() {
 	Resize(static_cast<int>(rc.Width()), static_cast<int>(rc.Height()));
 }
 
+void ScintillaGTK::SetScrollBars() {
+	if (scrollBarIdleID) {
+		// Only allow one scroll bar change to be queued
+		return;
+	}
+	constexpr gint priorityScrollBar = GDK_PRIORITY_REDRAW + 5;
+	// On GTK, unlike other platforms, modifying scrollbars inside some events including
+	// resizes causes problems. Deferring the modification to a lower priority (125) idle
+	// event avoids the problems. This code did not always work when the priority was
+	// higher than GTK's resize (GTK_PRIORITY_RESIZE=110) or redraw 
+	// (GDK_PRIORITY_REDRAW=120) idle tasks.
+	scrollBarIdleID = gdk_threads_add_idle_full(priorityScrollBar,
+		[](gpointer pSci) -> gboolean {
+			ScintillaGTK *sciThis = static_cast<ScintillaGTK *>(pSci);
+			sciThis->ChangeScrollBars();
+			sciThis->scrollBarIdleID = 0;
+			return FALSE;
+		},
+		this, nullptr);
+}
+
 void ScintillaGTK::NotifyChange() {
 	g_signal_emit(G_OBJECT(sci), scintilla_signals[COMMAND_SIGNAL], 0,
 		      Platform::LongFromTwoShorts(GetCtrlID(), SCEN_CHANGE), PWidget(wMain));
diff --git a/gtk/ScintillaGTK.h b/gtk/ScintillaGTK.h
index 9e9858c55..5db4ed3a5 100755
--- a/gtk/ScintillaGTK.h
+++ b/gtk/ScintillaGTK.h
@@ -82,6 +82,7 @@ class ScintillaGTK : public ScintillaBase {
 	bool repaintFullWindow;
 
 	guint styleIdleID;
+	guint scrollBarIdleID = 0;
 	FontOptions fontOptionsPrevious;
 	int accessibilityEnabled;
 	AtkObject *accessible;
@@ -133,6 +134,7 @@ private:
 	void SetHorizontalScrollPos() override;
 	bool ModifyScrollBars(Sci::Line nMax, Sci::Line nPage) override;
 	void ReconfigureScrollBars() override;
+	void SetScrollBars() override;
 	void NotifyChange() override;
 	void NotifyFocus(bool focus) override;
 	void NotifyParent(Scintilla::NotificationData scn) override;
-- 
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