Merge pull request #939 from elevatormind/backtrace-windows-disable

Fix issue #937

CMakeLists.txt

@@ -113,7 +113,9 @@ if(Backtrace_FOUND)
     include_directories(${Backtrace_INCLUDE_DIRS})
     add_compile_definitions(QET_CRASH_BACKTRACE)
 else()
-    message(STATUS "backtrace() not available: crash dumps will carry the log ring without a backtrace")
+    message(STATUS
+        "backtrace() not available: crash dumps will carry the log ring "
+        "without a backtrace")
 endif()
 
 find_package(SQLite3 REQUIRED)

INSTALL.md

@@ -271,6 +271,22 @@ mkdir build && cd build
 cmake .. -G Ninja -DBUILD_WITH_KF=OFF -DCMAKE_BUILD_TYPE=Release
 cmake --build .
 ```
+
+If `libbacktrace` is installed in your MSYS2 environment, pass the following
+cached CMake variables when configuring. They are only necessary in that
+case, because `FindBacktrace` needs them to locate the library:
+
+```sh
+cmake .. -G Ninja -DBUILD_WITH_KF=OFF -DCMAKE_BUILD_TYPE=Release \
+    -DBacktrace_INCLUDE_DIR=/c/msys64/clang64/include \
+    -DBacktrace_LIBRARY=/c/msys64/clang64/lib/libbacktrace.a
+```
+
+`Backtrace_INCLUDE_DIR` must point to the directory containing `backtrace.h`,
+and `Backtrace_LIBRARY` to the `libbacktrace.a` file. The paths above are the
+usual locations for the MSYS2 `clang64` environment; adjust them if your
+installation uses a different prefix.
+
 (KF6 isn't packaged in MSYS2 either, hence `-DBUILD_WITH_KF=OFF` again.)
 
 Using the Qt Online Installer's bundled MinGW kit instead: point

sources/palettegraphicsview.cpp

@@ -31,12 +31,14 @@ PaletteGraphicsView::PaletteGraphicsView(QWidget *parent) :
 	QGraphicsView(parent)
 {
 	qApp->installEventFilter(this);
+	setViewportUpdateMode(QGraphicsView::FullViewportUpdate);
 }
 
 PaletteGraphicsView::PaletteGraphicsView(QGraphicsScene *scene, QWidget *parent) :
 	QGraphicsView(scene, parent)
 {
 	qApp->installEventFilter(this);
+	setViewportUpdateMode(QGraphicsView::FullViewportUpdate);
 	listenToScene(scene);
 }
 

sources/palettegraphicsview.h

@@ -39,6 +39,18 @@ class QPainter;
 	listens to changed() on every scene it is given, which makes the scene
 	clear the flag before it emits. Set the scene through this class, not
 	through a QGraphicsView pointer.
+
+	The constructor also forces QGraphicsView::FullViewportUpdate in place
+	of the default MinimalViewportUpdate. #954 shipped with the default
+	kept, and moving an item then left conductor-shaped ghosts behind on
+	both a light and a dark palette, so the cause is shared code, not
+	paintInverted(): most likely listening to changed() at all, above,
+	changes which of QGraphicsScene's two update paths a view is on, and
+	MinimalViewportUpdate's job of turning the scene's reported dirty
+	rects into the smallest correct viewport region is where that would
+	show up first. FullViewportUpdate removes the need to get that region
+	right by repainting the whole viewport on every update; the class's
+	own benchmark already shows that cost is small next to a frame budget.
 */
 class PaletteGraphicsView : public QGraphicsView
 {

tests/qttest/CMakeLists.txt

@@ -157,7 +157,12 @@ add_test(NAME tst_crashhandler COMMAND tst_crashhandler)
 target_include_directories(tst_crashhandler PRIVATE ${QET_DIR}/sources)
 # Qt::Xml because crashhandler.cpp includes qetversion.h for the header it
 # builds at install() time, and that pulls in QDomElement.
-target_link_libraries(tst_crashhandler PRIVATE Qt::Test Qt::Xml ${Backtrace_LIBRARIES})
+if(Backtrace_FOUND)
+  target_link_libraries(tst_crashhandler PRIVATE
+    Qt::Test Qt::Xml ${Backtrace_LIBRARIES})
+else()
+  target_link_libraries(tst_crashhandler PRIVATE Qt::Test Qt::Xml)
+endif()
 
 # The crash-dump bookkeeping from #905: which dumps get listed, offered and
 # deleted, and what redact() masks. qetlogger.cpp needs exactly one symbol
@@ -176,7 +181,12 @@ target_include_directories(tst_crashdumps PRIVATE
   ${QET_DIR}/sources
   ${QET_DIR}/sources/NameList
   ${QET_DIR}/pugixml/src)
-target_link_libraries(tst_crashdumps PRIVATE Qt::Test Qt::Widgets Qt::Xml ${Backtrace_LIBRARIES})
+if(Backtrace_FOUND)
+  target_link_libraries(tst_crashdumps PRIVATE
+    Qt::Test Qt::Widgets Qt::Xml ${Backtrace_LIBRARIES})
+else()
+  target_link_libraries(tst_crashdumps PRIVATE Qt::Test Qt::Widgets Qt::Xml)
+endif()
 
 add_executable(
   tst_menubarkeyboard

tests/qttest/tst_crashhandler.cpp

@@ -100,7 +100,9 @@ void tst_CrashHandler::formatsTheHandledSignals()
 {
 	QCOMPARE(format(SIGSEGV), QByteArray::number(SIGSEGV));
 	QCOMPARE(format(SIGABRT), QByteArray::number(SIGABRT));
+#if defined(SIGBUS)
 	QCOMPARE(format(SIGBUS), QByteArray::number(SIGBUS));
+#endif
 	QCOMPARE(format(SIGFPE), QByteArray::number(SIGFPE));
 	QCOMPARE(format(SIGILL), QByteArray::number(SIGILL));
 }