From 33c7edaaf479e5d06513ce0dfe3e2de470227d70 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Fl=C3=B6ser?= <mgraesslin@kde.org>
Date: Sat, 12 Jan 2019 14:39:16 +0100
Subject: [PATCH] Use reserve on QVector<Phase2Data>

Summary:
We know that the maximum size is the number of windows in stacking
order. It might be that some are skipped as they are not ready for
painting, but overall it's better to reserve a little bit too much
memory than to have a growing QVector.

Test Plan: Compiles

Reviewers: #kwin

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D18208
---
 scene.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/scene.cpp b/scene.cpp
index 584be708c3..fa91f619f2 100644
--- a/scene.cpp
+++ b/scene.cpp
@@ -207,6 +207,7 @@ void Scene::paintGenericScreen(int orig_mask, ScreenPaintData)
         paintBackground(infiniteRegion());
     }
     QVector<Phase2Data> phase2;
+    phase2.reserve(stacking_order.size());
     foreach (Window * w, stacking_order) { // bottom to top
         Toplevel* topw = w->window();
 
@@ -250,6 +251,7 @@ void Scene::paintSimpleScreen(int orig_mask, QRegion region)
     assert((orig_mask & (PAINT_SCREEN_TRANSFORMED
                          | PAINT_SCREEN_WITH_TRANSFORMED_WINDOWS)) == 0);
     QVector<Phase2Data> phase2data;
+    phase2data.reserve(stacking_order.size());
 
     QRegion dirtyArea = region;
     bool opaqueFullscreen(false);