From bd52b6791e8b75690a4bfa9fa89d8dc88fe3c925 Mon Sep 17 00:00:00 2001
From: Vlad Zahorodnii <vlad.zahorodnii@kde.org>
Date: Sun, 26 Jan 2020 15:08:52 +0200
Subject: [PATCH] Schedule a decoration repaint when client is resized

Summary:
If a client has been resized, it doesn't necessarily mean that the
decoration theme will schedule full repaint of the window frame. In
OpenGL and Xrender scene, we have a little hack that forces a full
repaint of window borders. However, we don't have one in QPainter
scene which causes all sorts of weird looking artifacts when resizing
a server-side decorated client.

We could add yet another hack in the QPainter scene, but a better
approach to tackle this problem would be to make DecoratedClient
schedule a full repaint of the decoration. It makes code in scene
plugins more straightforward and prevents us from repeating the same
mistake again.

Test Plan:
No longer able to see invisible decoration borders when
using QPainter render backend.

Reviewers: #kwin, davidedmundson

Reviewed By: #kwin, davidedmundson

Subscribers: davidedmundson, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D26927
---
 decorations/decorationrenderer.cpp       | 4 ++--
 plugins/scenes/opengl/scene_opengl.cpp   | 9 ++++-----
 plugins/scenes/xrender/scene_xrender.cpp | 1 -
 3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/decorations/decorationrenderer.cpp b/decorations/decorationrenderer.cpp
index ef753f27c4..5e28e40b71 100644
--- a/decorations/decorationrenderer.cpp
+++ b/decorations/decorationrenderer.cpp
@@ -40,12 +40,12 @@ Renderer::Renderer(DecoratedClientImpl *client)
     , m_imageSizesDirty(true)
 {
     auto markImageSizesDirty = [this]{
+        schedule(m_client->client()->rect());
         m_imageSizesDirty = true;
     };
     connect(client->client(), &AbstractClient::screenScaleChanged, this, markImageSizesDirty);
     connect(client->decoration(), &KDecoration2::Decoration::bordersChanged, this, markImageSizesDirty);
-    connect(client->decoratedClient(), &KDecoration2::DecoratedClient::widthChanged, this, markImageSizesDirty);
-    connect(client->decoratedClient(), &KDecoration2::DecoratedClient::heightChanged, this, markImageSizesDirty);
+    connect(client->decoratedClient(), &KDecoration2::DecoratedClient::sizeChanged, this, markImageSizesDirty);
 }
 
 Renderer::~Renderer() = default;
diff --git a/plugins/scenes/opengl/scene_opengl.cpp b/plugins/scenes/opengl/scene_opengl.cpp
index 3b5d2432d0..d15e503174 100644
--- a/plugins/scenes/opengl/scene_opengl.cpp
+++ b/plugins/scenes/opengl/scene_opengl.cpp
@@ -2562,11 +2562,10 @@ static void clamp(QImage &image, const QRect &viewport)
 void SceneOpenGLDecorationRenderer::render()
 {
     const QRegion scheduled = getScheduled();
-    const bool dirty = areImageSizesDirty();
-    if (scheduled.isEmpty() && !dirty) {
+    if (scheduled.isEmpty()) {
         return;
     }
-    if (dirty) {
+    if (areImageSizesDirty()) {
         resizeTexture();
         resetImageSizesDirty();
     }
@@ -2579,8 +2578,6 @@ void SceneOpenGLDecorationRenderer::render()
     QRect left, top, right, bottom;
     client()->client()->layoutDecorationRects(left, top, right, bottom);
 
-    const QRect geometry = dirty ? QRect(QPoint(0, 0), client()->client()->size()) : scheduled.boundingRect();
-
     // We pad each part in the decoration atlas in order to avoid texture bleeding.
     const int padding = 1;
 
@@ -2634,6 +2631,8 @@ void SceneOpenGLDecorationRenderer::render()
         m_texture->update(image, (position + dirtyOffset - viewport.topLeft()) * image.devicePixelRatio());
     };
 
+    const QRect geometry = scheduled.boundingRect();
+
     const QPoint topPosition(padding, padding);
     const QPoint bottomPosition(padding, topPosition.y() + top.height() + 2 * padding);
     const QPoint leftPosition(padding, bottomPosition.y() + bottom.height() + 2 * padding);
diff --git a/plugins/scenes/xrender/scene_xrender.cpp b/plugins/scenes/xrender/scene_xrender.cpp
index 1afeeedcb2..acab174a56 100644
--- a/plugins/scenes/xrender/scene_xrender.cpp
+++ b/plugins/scenes/xrender/scene_xrender.cpp
@@ -1229,7 +1229,6 @@ void SceneXRenderDecorationRenderer::render()
     if (areImageSizesDirty()) {
         resizePixmaps();
         resetImageSizesDirty();
-        scheduled = client()->client()->decorationRect();
     }
 
     const QRect top(QPoint(0, 0), m_sizes[int(DecorationPart::Top)]);