From b5e497e6ff2e9c5fc4d369b36d669aa916edcdc3 Mon Sep 17 00:00:00 2001
From: Yuhang Zhao <2546789017@qq.com>
Date: Thu, 5 Nov 2020 18:25:44 +0800
Subject: [PATCH] UNIX: fall back to traditional way.

The startSystemMove and startSystemResize may
return false on some systems, just fallback to
use the old way to move and resize the window.

Signed-off-by: Yuhang Zhao <2546789017@qq.com>
---
 framelesshelper.cpp | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/framelesshelper.cpp b/framelesshelper.cpp
index 4a9c829..83588a8 100644
--- a/framelesshelper.cpp
+++ b/framelesshelper.cpp
@@ -319,6 +319,7 @@ bool FramelessHelper::eventFilter(QObject *object, QEvent *event)
 {
     Q_ASSERT(object);
     Q_ASSERT(event);
+    QPointF m_pCurMousePos = {};
     const auto isWindowTopLevel = [](QObject *window) -> bool {
         Q_ASSERT(window);
         if (window->isWindowType()) {
@@ -486,21 +487,32 @@ bool FramelessHelper::eventFilter(QObject *object, QEvent *event)
         return false;
     };
     const auto moveOrResize =
-        [this, &getWindowEdges, &isResizePermitted, &isInTitlebarArea](const QPointF &globalPoint,
-                                                                       const QPointF &point,
-                                                                       QObject *object) {
+        [this,
+         &getWindowEdges,
+         &isResizePermitted,
+         &isInTitlebarArea,
+         &m_pCurMousePos](const QPointF &globalPoint, const QPointF &point, QObject *object) {
             Q_ASSERT(object);
             QWindow *window = getWindowHandle(object);
             if (window) {
+                const int deltaX = m_pCurMousePos.x() - globalPoint.x();
+                const int deltaY = m_pCurMousePos.y() - globalPoint.y();
                 const Qt::Edges edges = getWindowEdges(point, window->width(), window->height());
                 if (edges == Qt::Edges{}) {
                     if (isInTitlebarArea(globalPoint, point, object)) {
-                        window->startSystemMove();
+                        if (!window->startSystemMove()) {
+                            // Fallback to the traditional way.
+                            window->setX(window->x() + deltaX);
+                            window->setY(window->y() + deltaY);
+                        }
                     }
                 } else {
                     if (window->windowStates().testFlag(Qt::WindowState::WindowNoState)
                         && isResizePermitted(globalPoint, point, object) && getResizable(object)) {
-                        window->startSystemResize(edges);
+                        if (!window->startSystemResize(edges)) {
+                            // Fallback to the traditional way.
+                            window->resize(window->width() + deltaX, window->height() + deltaY);
+                        }
                     }
                 }
             } else {
@@ -568,6 +580,7 @@ bool FramelessHelper::eventFilter(QObject *object, QEvent *event)
     case QEvent::MouseMove: {
         const auto mouseEvent = static_cast<QMouseEvent *>(event);
         if (mouseEvent) {
+            m_pCurMousePos = mouseEvent->screenPos();
             QWindow *window = getWindowHandle(object);
             if (window) {
                 if (window->windowStates().testFlag(Qt::WindowState::WindowNoState)