Optimize UIDiffView::NewMultiFileDiffViewer to not trash children creation with invalidations.

src/eepp/ui/tools/uidiffview.cpp

@@ -4,6 +4,7 @@
 #include <eepp/graphics/sprite.hpp>
 #include <eepp/graphics/text.hpp>
 #include <eepp/graphics/texturefactory.hpp>
+#include <eepp/scene/scenemanager.hpp>
 #include <eepp/system/filesystem.hpp>
 #include <eepp/system/log.hpp>
 #include <eepp/ui/doc/syntaxdefinitionmanager.hpp>
@@ -80,13 +81,17 @@ static Sprite* setImageViewerImage( UIImageViewer* viewer, Image* image ) {
 
 UIScrollView* UIDiffView::NewMultiFileDiffViewer( const std::string& patchText,
 												  const std::string& repoPath, ViewMode viewMode ) {
+	auto diffs = UIDiffView::splitDiff( patchText );
+	auto* uiSceneNode = SceneManager::instance()->getUISceneNode();
+	const bool wasLoading = uiSceneNode && uiSceneNode->isLoading();
+	if ( uiSceneNode )
+		uiSceneNode->setIsLoading( true );
+
 	auto scrollView = UIScrollView::New();
 	auto vbox = UILinearLayout::NewVertical();
 	vbox->setParent( scrollView );
 	vbox->setLayoutSizePolicy( SizePolicy::MatchParent, SizePolicy::WrapContent );
 
-	auto diffs = UIDiffView::splitDiff( patchText );
-
 	for ( const auto& diff : diffs ) {
 		auto* diffView = UIDiffView::New();
 		diffView->setViewMode( viewMode );
@@ -98,6 +103,18 @@ UIScrollView* UIDiffView::NewMultiFileDiffViewer( const std::string& patchText,
 		diffView->loadFromPatch( diff, "", "", repoPath );
 	}
 
+	if ( uiSceneNode ) {
+		uiSceneNode->setIsLoading( wasLoading );
+		if ( !wasLoading ) {
+			// A diff view owns several editors, scroll bars, toggles and image viewers. Queueing
+			// each intermediate widget separately makes style invalidation scan an ever-growing
+			// dirty set. One recursive invalidation of the completed tree provides the same final
+			// styling.
+			uiSceneNode->invalidateStyle( scrollView, true );
+			uiSceneNode->invalidateStyleState( scrollView, true, true );
+		}
+	}
+
 	return scrollView;
 }
 

src/tests/unit_tests/uidiffview_tests.cpp

@@ -6,6 +6,7 @@
 #include <eepp/ui/tools/uiimageviewer.hpp>
 #include <eepp/ui/uiapplication.hpp>
 #include <eepp/ui/uicodeeditor.hpp>
+#include <eepp/ui/uiscenenode.hpp>
 #include <eepp/ui/uiscrollview.hpp>
 
 using namespace EE;
@@ -143,6 +144,25 @@ diff --git a/second.txt b/second.txt
 	eeDelete( viewer );
 }
 
+UTEST( UIDiffView, MultiFileViewerHandlesLargePatches ) {
+	UIApplication app( WindowSettings{ 800, 600, "eepp - unit tests" } );
+	app.getUI()->flushDirtyStyleAndLayout();
+	constexpr size_t fileCount = 128;
+	std::string patchText;
+	patchText.reserve( fileCount * 160 );
+	for ( size_t i = 0; i < fileCount; ++i ) {
+		const std::string fileName( "file" + std::to_string( i ) + ".txt" );
+		patchText += "diff --git a/" + fileName + " b/" + fileName + "\n--- a/" + fileName +
+					 "\n+++ b/" + fileName + "\n@@ -1 +1 @@\n-old\n+new\n";
+	}
+
+	auto* viewer = UIDiffView::NewMultiFileDiffViewer( patchText );
+	EXPECT_EQ( fileCount, viewer->findAllByType<UIDiffView>( UI_TYPE_DIFF_VIEW ).size() );
+	EXPECT_FALSE( viewer->getUISceneNode()->isLoading() );
+
+	eeDelete( viewer );
+}
+
 UTEST( UIDiffView, LoadFromFileImageDiffUsesImageViewers ) {
 	UIApplication app( WindowSettings{ 800, 600, "eepp - unit tests" } );