diff options
| author | Liang Qi <liang.qi@qt.io> | 2017-01-24 10:33:37 +0100 |
|---|---|---|
| committer | Oswald Buddenhagen <oswald.buddenhagen@qt.io> | 2017-01-25 20:06:06 +0100 |
| commit | 318b58562ae89453fb98e8145cd0440e14ba60b0 (patch) | |
| tree | 622bc032cf076b4569621032f3a3315d95c3ae88 /src/widgets/doc/src/model-view-programming.qdoc | |
| parent | c28fde3fdac19fd5a5f614bb7983080031c924b3 (diff) | |
| parent | 79352528a1726b4551ea4d9285dd2394dd0d43da (diff) | |
Merge remote-tracking branch 'origin/5.8' into dev
Conflicts:
.qmake.conf
mkspecs/common/msvc-desktop.conf
mkspecs/common/msvc-version.conf
mkspecs/common/winrt_winphone/qmake.conf
mkspecs/features/mac/default_post.prf
mkspecs/features/mac/sdk.prf
mkspecs/features/qt.prf
mkspecs/features/uikit/default_post.prf
mkspecs/features/winrt/default_pre.prf
mkspecs/winphone-arm-msvc2013/qmake.conf
mkspecs/winphone-x86-msvc2013/qmake.conf
mkspecs/winrt-arm-msvc2013/qmake.conf
mkspecs/winrt-x64-msvc2013/qmake.conf
mkspecs/winrt-x86-msvc2013/qmake.conf
qmake/generators/win32/msvc_vcproj.cpp
src/gui/kernel/qwindowsysteminterface.cpp
src/network/kernel/qhostaddress.cpp
src/plugins/platforms/mirclient/qmirclientplugin.cpp
src/plugins/platforms/mirclient/qmirclientplugin.h
src/widgets/util/qsystemtrayicon.cpp
tests/auto/widgets/itemviews/qlistview/tst_qlistview.cpp
tools/configure/Makefile.mingw
tools/configure/Makefile.win32
Done-with: Jake Petroules <jake.petroules@qt.io>
Done-with: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Change-Id: I4be3262d3994e11929d3b1ded2c3379783797dbe
Diffstat (limited to 'src/widgets/doc/src/model-view-programming.qdoc')
| -rw-r--r-- | src/widgets/doc/src/model-view-programming.qdoc | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/src/widgets/doc/src/model-view-programming.qdoc b/src/widgets/doc/src/model-view-programming.qdoc index e727d7fe56..84819e8c1a 100644 --- a/src/widgets/doc/src/model-view-programming.qdoc +++ b/src/widgets/doc/src/model-view-programming.qdoc @@ -2070,9 +2070,22 @@ Normally, the begin and end functions are capable of informing other components about changes to the model's underlying structure. For more complex changes to the - model's structure, perhaps involving internal reorganization or sorting of data, - it is necessary to emit the \l{QAbstractItemModel::layoutChanged()}{layoutChanged()} - signal to cause any attached views to be updated. + model's structure, perhaps involving internal reorganization, sorting of data or + any other structural change, it is necessary to perform the following sequence: + + \li Emit the \l{QAbstractItemModel::layoutAboutToBeChanged()}{layoutAboutToBeChanged()} signal + \li Update internal data which represents the structure of the model. + \li Update persistent indexes using \l{QAbstractItemModel::changePersistentIndexList()}{changePersistentIndexList()} + \li Emit the \l{QAbstractItemModel::layoutChanged()}{layoutChanged()} signal. + + This sequence can be used for any structural update in lieu of the more + high-level and convenient protected methods. For example, if a model of + two million rows needs to have all odd numbered rows removed, that + is 1 million discountiguous ranges of 1 element each. It would be + possible to use beginRemoveRows and endRemoveRows 1 million times, but + that would obviously be inefficient. Instead, this can be signalled as a + single layout change which updates all necessary persistent indexes at + once. \section3 Lazy population of model data |