From 6b1bc6c137844171f87d808b1b95b7371c41d814 Mon Sep 17 00:00:00 2001
From: Harshad Vedartham <harshad1@zoho.com>
Date: Tue, 27 Aug 2024 11:38:05 -0700
Subject: [PATCH] Yet more massaging spans for performance

---
 .../format/todotxt/TodoTxtSyntaxHighlighter.java |  3 +--
 .../frontend/textview/HighlightingEditor.java    | 15 ++++++++++++---
 .../frontend/textview/SyntaxHighlighterBase.java | 16 +++++++++++-----
 3 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/app/src/main/java/net/gsantner/markor/format/todotxt/TodoTxtSyntaxHighlighter.java b/app/src/main/java/net/gsantner/markor/format/todotxt/TodoTxtSyntaxHighlighter.java
index 8301e9b82..37bfd4fb1 100644
--- a/app/src/main/java/net/gsantner/markor/format/todotxt/TodoTxtSyntaxHighlighter.java
+++ b/app/src/main/java/net/gsantner/markor/format/todotxt/TodoTxtSyntaxHighlighter.java
@@ -11,7 +11,6 @@
 import android.graphics.Paint;
 import android.text.style.LineBackgroundSpan;
 import android.text.style.LineHeightSpan;
-import android.text.style.UpdateLayout;
 
 import androidx.annotation.ColorInt;
 import androidx.annotation.NonNull;
@@ -45,7 +44,7 @@ public void generateSpans() {
     }
 
     // Adds spacing and divider line between paragraphs
-    public static class ParagraphDividerSpan implements LineBackgroundSpan, LineHeightSpan, UpdateLayout {
+    public static class ParagraphDividerSpan implements LineBackgroundSpan, LineHeightSpan, StaticSpan {
         private final int _lineColor;
         private Integer _origAscent = null;
 
diff --git a/app/src/main/java/net/gsantner/markor/frontend/textview/HighlightingEditor.java b/app/src/main/java/net/gsantner/markor/frontend/textview/HighlightingEditor.java
index 618335808..6c3c2d7ce 100644
--- a/app/src/main/java/net/gsantner/markor/frontend/textview/HighlightingEditor.java
+++ b/app/src/main/java/net/gsantner/markor/frontend/textview/HighlightingEditor.java
@@ -129,6 +129,15 @@ protected void onDraw(Canvas canvas) {
     // Highlighting
     // ---------------------------------------------------------------------------------------------
 
+    private void batch(final Runnable runnable) {
+        try {
+            beginBatchEdit();
+            runnable.run();
+        } finally {
+            endBatchEdit();
+        }
+    }
+
     private boolean isScrollSignificant() {
         return Math.abs(_oldHlRect.top - _hlRect.top) > _hlShiftThreshold ||
                 Math.abs(_hlRect.bottom - _oldHlRect.bottom) > _hlShiftThreshold;
@@ -146,14 +155,14 @@ private boolean runHighlight(final boolean recompute) {
 
     private void updateHighlighting() {
         if (runHighlight(false)) {
-            _hl.clearDynamic().applyDynamic(hlRegion());
+            batch(() -> _hl.clearDynamic().applyDynamic(hlRegion()));
             _oldHlRect.set(_hlRect);
         }
     }
 
     public void recomputeHighlighting() {
         if (runHighlight(true)) {
-            _hl.clearAll().recompute().applyStatic().applyDynamic(hlRegion());
+            batch(() -> _hl.clearAll().recompute().applyStatic().applyDynamic(hlRegion()));
         }
     }
 
@@ -174,7 +183,7 @@ private synchronized void _recomputeHighlightingWorker() {
         _hl.compute();
         post(() -> {
             if (_textUnchangedWhileHighlighting.get()) {
-                _hl.clearAll().setComputed().applyStatic().applyDynamic(hlRegion());
+                batch(() -> _hl.clearAll().setComputed().applyStatic().applyDynamic(hlRegion()));
             }
         });
     }
diff --git a/app/src/main/java/net/gsantner/markor/frontend/textview/SyntaxHighlighterBase.java b/app/src/main/java/net/gsantner/markor/frontend/textview/SyntaxHighlighterBase.java
index a30b3ce7c..6eddc7ff7 100644
--- a/app/src/main/java/net/gsantner/markor/frontend/textview/SyntaxHighlighterBase.java
+++ b/app/src/main/java/net/gsantner/markor/frontend/textview/SyntaxHighlighterBase.java
@@ -103,7 +103,7 @@ public SyntaxHighlighterBase configure(@Nullable final Paint paint) {
     // ---------------------------------------------------------------------------------------------
 
     /**
-     * A class representing any span
+     * A class holding any span
      */
     public static class SpanGroup implements Comparable<SpanGroup> {
         int start, end;
@@ -114,7 +114,7 @@ public static class SpanGroup implements Comparable<SpanGroup> {
             span = o;
             start = s;
             end = e;
-            isStatic = o instanceof UpdateLayout;
+            isStatic = (span instanceof UpdateLayout || span instanceof StaticSpan);
         }
 
         @Override
@@ -127,6 +127,9 @@ private static class ForceUpdateLayout implements UpdateLayout {
         // Empty class - just implements UpdateLayout
     }
 
+    public interface StaticSpan extends UpdateAppearance {
+    }
+
     private final ForceUpdateLayout _layoutUpdater;
 
     private final List<SpanGroup> _groups, _groupBuffer;
@@ -189,7 +192,7 @@ public SyntaxHighlighterBase clearStatic() {
 
         _staticApplied = false;
 
-        return this;
+        return reflow();
     }
 
     /**
@@ -262,6 +265,7 @@ private SyntaxHighlighterBase applyFixup() {
                     break;
                 } else {
                     group.start += _fixupDelta;
+                    group.end += _fixupDelta;
                 }
             }
             clearFixup();
@@ -325,6 +329,8 @@ public SyntaxHighlighterBase applyDynamic(final int[] range) {
         return this;
     }
 
+
+
     public SyntaxHighlighterBase applyStatic() {
         if (_spannable == null || _staticApplied) {
             return this;
@@ -334,13 +340,13 @@ public SyntaxHighlighterBase applyStatic() {
 
         for (final SpanGroup group : _groups) {
             if (group.isStatic) {
-                _spannable.setSpan(group.span, group.start, group.start + group.end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+                _spannable.setSpan(group.span, group.start, group.end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
             }
         }
 
         _staticApplied = true;
 
-        return this;
+        return reflow();
     }
 
     public final SyntaxHighlighterBase reflow() {