Bluetooth Chat example: update UI

* Add some icons for Light and Dark themes. Implement switching between
  themes by listening to QStyleHints::colorSchemeChanged() signal and
  manually picking the proper icon.
* Rework the desing to get rid of the unnecessary "Quit" button, and
  also change the layout of buttons in the connection dialog.
* Update the screenshot in the documentation.

As a drive-by fix, make sure that the cursor is always at the end of
QTextEdit before showing a new message. The user can change the cursor
position by clicking/selecting the text, and this could previously lead
to some bugs in message visualization.

Fixes: QTBUG-118875
Pick-to: 6.5
Change-Id: Ia3a9dec3dae0d1411643ed851eba0ab4dc96a47f
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>
(cherry picked from commit 6eb66322f0933de004baf35a96c5dd06d5d62ff6)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

27 files changed, 160 insertions, 25 deletions

diff --git a/examples/bluetooth/btchat/CMakeLists.txt b/examples/bluetooth/btchat/CMakeLists.txt
index 6d2bd0b9..0e4e217c 100644
--- a/examples/bluetooth/btchat/CMakeLists.txt
+++ b/examples/bluetooth/btchat/CMakeLists.txt
@@ -22,6 +22,18 @@ qt_add_executable(btchat
     remoteselector.cpp remoteselector.h remoteselector.ui
 )
 
+set(icon_files)
+foreach(icon IN ITEMS bluetooth bluetooth_dark send send_dark)
+    foreach(scale IN ITEMS "" "@2" "@3" "@4")
+        list(APPEND icon_files "icons/btchat/24x24${scale}/${icon}.png")
+    endforeach()
+endforeach()
+
+qt_add_resources(btchat "theme" FILES
+    ${icon_files}
+    icons/btchat/index.theme
+)
+
 set_target_properties(btchat PROPERTIES
     WIN32_EXECUTABLE TRUE
     MACOSX_BUNDLE TRUE
diff --git a/examples/bluetooth/btchat/btchat.pro b/examples/bluetooth/btchat/btchat.pro
index 7e0c976f..0d7b5f77 100644
--- a/examples/bluetooth/btchat/btchat.pro
+++ b/examples/bluetooth/btchat/btchat.pro
@@ -21,6 +21,29 @@ FORMS = \
     chat.ui \
     remoteselector.ui
 
+theme_resources.files = \
+    icons/btchat/24x24/bluetooth.png \
+    icons/btchat/24x24/bluetooth_dark.png \
+    icons/btchat/24x24/send.png \
+    icons/btchat/24x24/send_dark.png \
+    icons/btchat/24x24@2/bluetooth.png \
+    icons/btchat/24x24@2/bluetooth_dark.png \
+    icons/btchat/24x24@2/send.png \
+    icons/btchat/24x24@2/send_dark.png \
+    icons/btchat/24x24@3/bluetooth.png \
+    icons/btchat/24x24@3/bluetooth_dark.png \
+    icons/btchat/24x24@3/send.png \
+    icons/btchat/24x24@3/send_dark.png \
+    icons/btchat/24x24@4/bluetooth.png \
+    icons/btchat/24x24@4/bluetooth_dark.png \
+    icons/btchat/24x24@4/send.png \
+    icons/btchat/24x24@4/send_dark.png \
+    icons/btchat/index.theme
+
+theme_resources.prefix = /
+
+RESOURCES += theme_resources
+
 ios: QMAKE_INFO_PLIST = ../shared/Info.qmake.ios.plist
 macos: QMAKE_INFO_PLIST = ../shared/Info.qmake.macos.plist
 
diff --git a/examples/bluetooth/btchat/chat.cpp b/examples/bluetooth/btchat/chat.cpp
index 288f4641..b323b2a3 100644
--- a/examples/bluetooth/btchat/chat.cpp
+++ b/examples/bluetooth/btchat/chat.cpp
@@ -13,6 +13,9 @@
 #include <QtBluetooth/qbluetoothlocaldevice.h>
 #include <QtBluetooth/qbluetoothuuid.h>
 
+#include <QtGui/qguiapplication.h>
+#include <QtGui/qstylehints.h>
+
 #if QT_CONFIG(permissions)
 #include <QtCore/qcoreapplication.h>
 #include <QtCore/qpermissions.h>
@@ -32,12 +35,15 @@ Chat::Chat(QWidget *parent)
     //! [Construct UI]
     ui->setupUi(this);
 
-    connect(ui->quitButton, &QPushButton::clicked, this, &Chat::accept);
     connect(ui->connectButton, &QPushButton::clicked, this, &Chat::connectClicked);
     connect(ui->sendButton, &QPushButton::clicked, this, &Chat::sendClicked);
     //! [Construct UI]
     ui->connectButton->setFocus();
 
+    QStyleHints *styleHints = qGuiApp->styleHints();
+    updateIcons(styleHints->colorScheme());
+    connect(styleHints, &QStyleHints::colorSchemeChanged, this, &Chat::updateIcons);
+
     initBluetooth();
 }
 
@@ -106,6 +112,15 @@ void Chat::initBluetooth()
     //! [Get local device name]
 }
 
+void Chat::updateIcons(Qt::ColorScheme scheme)
+{
+    const QString bluetoothIconName = (scheme == Qt::ColorScheme::Dark) ? u"bluetooth_dark"_s
+                                                                        : u"bluetooth"_s;
+    const QString sendIconName = (scheme == Qt::ColorScheme::Dark) ? u"send_dark"_s : u"send"_s;
+    ui->sendButton->setIcon(QIcon::fromTheme(sendIconName));
+    ui->connectButton->setIcon(QIcon::fromTheme(bluetoothIconName));
+}
+
 //! [clientConnected clientDisconnected]
 void Chat::clientConnected(const QString &name)
 {
@@ -237,6 +252,7 @@ void Chat::sendClicked()
 //! [showMessage]
 void Chat::showMessage(const QString &sender, const QString &message)
 {
+    ui->chat->moveCursor(QTextCursor::End);
     ui->chat->insertPlainText(QString::fromLatin1("%1: %2\n").arg(sender, message));
     ui->chat->ensureCursorVisible();
 }
diff --git a/examples/bluetooth/btchat/chat.h b/examples/bluetooth/btchat/chat.h
index d9a22ca7..6230e639 100644
--- a/examples/bluetooth/btchat/chat.h
+++ b/examples/bluetooth/btchat/chat.h
@@ -42,6 +42,8 @@ private slots:
 
     void initBluetooth();
 
+    void updateIcons(Qt::ColorScheme scheme);
+
 private:
     int adapterFromUserSelection() const;
     int currentAdapterIndex = 0;
diff --git a/examples/bluetooth/btchat/chat.ui b/examples/bluetooth/btchat/chat.ui
index 639626f1..bea3d2ee 100644
--- a/examples/bluetooth/btchat/chat.ui
+++ b/examples/bluetooth/btchat/chat.ui
@@ -50,12 +50,16 @@
    <item>
     <layout class="QHBoxLayout" name="horizontalLayout">
      <item>
-      <widget class="QLineEdit" name="sendText"/>
+      <widget class="QLineEdit" name="sendText">
+       <property name="placeholderText">
+        <string>Enter message</string>
+       </property>
+      </widget>
      </item>
      <item>
       <widget class="QPushButton" name="sendButton">
        <property name="text">
-        <string>Send</string>
+        <string/>
        </property>
        <property name="default">
         <bool>true</bool>
@@ -89,15 +93,21 @@
        </property>
       </widget>
      </item>
+     <item>
+      <spacer name="horizontalSpacer_2">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
     </layout>
    </item>
-   <item>
-    <widget class="QPushButton" name="quitButton">
-     <property name="text">
-      <string>Quit</string>
-     </property>
-    </widget>
-   </item>
   </layout>
  </widget>
  <resources/>
diff --git a/examples/bluetooth/btchat/doc/images/btchat-example.png b/examples/bluetooth/btchat/doc/images/btchat-example.png
index 2da48731..acfadf5c 100644
--- a/examples/bluetooth/btchat/doc/images/btchat-example.png
+++ b/examples/bluetooth/btchat/doc/images/btchat-example.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24/bluetooth.png b/examples/bluetooth/btchat/icons/btchat/24x24/bluetooth.png
new file mode 100644
index 00000000..832dd042
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24/bluetooth.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24/bluetooth_dark.png b/examples/bluetooth/btchat/icons/btchat/24x24/bluetooth_dark.png
new file mode 100644
index 00000000..48b772d0
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24/bluetooth_dark.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24/send.png b/examples/bluetooth/btchat/icons/btchat/24x24/send.png
new file mode 100644
index 00000000..dfce248a
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24/send.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24/send_dark.png b/examples/bluetooth/btchat/icons/btchat/24x24/send_dark.png
new file mode 100644
index 00000000..66e78daf
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24/send_dark.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24@2/bluetooth.png b/examples/bluetooth/btchat/icons/btchat/24x24@2/bluetooth.png
new file mode 100644
index 00000000..12bbb81d
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24@2/bluetooth.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24@2/bluetooth_dark.png b/examples/bluetooth/btchat/icons/btchat/24x24@2/bluetooth_dark.png
new file mode 100644
index 00000000..f3456e6f
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24@2/bluetooth_dark.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24@2/send.png b/examples/bluetooth/btchat/icons/btchat/24x24@2/send.png
new file mode 100644
index 00000000..8c4d5d0e
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24@2/send.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24@2/send_dark.png b/examples/bluetooth/btchat/icons/btchat/24x24@2/send_dark.png
new file mode 100644
index 00000000..03b597c3
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24@2/send_dark.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24@3/bluetooth.png b/examples/bluetooth/btchat/icons/btchat/24x24@3/bluetooth.png
new file mode 100644
index 00000000..235b91aa
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24@3/bluetooth.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24@3/bluetooth_dark.png b/examples/bluetooth/btchat/icons/btchat/24x24@3/bluetooth_dark.png
new file mode 100644
index 00000000..c64aa4a9
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24@3/bluetooth_dark.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24@3/send.png b/examples/bluetooth/btchat/icons/btchat/24x24@3/send.png
new file mode 100644
index 00000000..3d15b197
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24@3/send.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24@3/send_dark.png b/examples/bluetooth/btchat/icons/btchat/24x24@3/send_dark.png
new file mode 100644
index 00000000..7f1a9f4d
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24@3/send_dark.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24@4/bluetooth.png b/examples/bluetooth/btchat/icons/btchat/24x24@4/bluetooth.png
new file mode 100644
index 00000000..bad3e2ea
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24@4/bluetooth.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24@4/bluetooth_dark.png b/examples/bluetooth/btchat/icons/btchat/24x24@4/bluetooth_dark.png
new file mode 100644
index 00000000..01f420b0
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24@4/bluetooth_dark.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24@4/send.png b/examples/bluetooth/btchat/icons/btchat/24x24@4/send.png
new file mode 100644
index 00000000..c931f7a0
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24@4/send.png
diff --git a/examples/bluetooth/btchat/icons/btchat/24x24@4/send_dark.png b/examples/bluetooth/btchat/icons/btchat/24x24@4/send_dark.png
new file mode 100644
index 00000000..8b801207
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/24x24@4/send_dark.png
diff --git a/examples/bluetooth/btchat/icons/btchat/index.theme b/examples/bluetooth/btchat/icons/btchat/index.theme
new file mode 100644
index 00000000..3209f84f
--- /dev/null
+++ b/examples/bluetooth/btchat/icons/btchat/index.theme
@@ -0,0 +1,22 @@
+[Icon Theme]
+Name=btchat
+Directories=24x24,24x24@2,24x24@3,24x24@4
+
+[24x24]
+Size=24
+Type=Fixed
+
+[24x24@2]
+Size=24
+Scale=2
+Type=Fixed
+
+[24x24@3]
+Size=24
+Scale=3
+Type=Fixed
+
+[24x24@4]
+Size=24
+Scale=4
+Type=Fixed
diff --git a/examples/bluetooth/btchat/main.cpp b/examples/bluetooth/btchat/main.cpp
index 6347c914..16c8e272 100644
--- a/examples/bluetooth/btchat/main.cpp
+++ b/examples/bluetooth/btchat/main.cpp
@@ -6,11 +6,15 @@
 #include <QtCore/qloggingcategory.h>
 #include <QtWidgets/qapplication.h>
 
+using namespace Qt::StringLiterals;
+
 int main(int argc, char *argv[])
 {
     // QLoggingCategory::setFilterRules(QStringLiteral("qt.bluetooth* = true"));
     QApplication app(argc, argv);
 
+    QIcon::setThemeName(u"btchat"_s);
+
     Chat d;
     QObject::connect(&d, &Chat::accepted, &app, &QApplication::quit);
 
diff --git a/examples/bluetooth/btchat/remoteselector.cpp b/examples/bluetooth/btchat/remoteselector.cpp
index 7ab496bd..2c1f9a00 100644
--- a/examples/bluetooth/btchat/remoteselector.cpp
+++ b/examples/bluetooth/btchat/remoteselector.cpp
@@ -9,8 +9,13 @@
 #include <QtBluetooth/qbluetoothservicediscoveryagent.h>
 #include <QtBluetooth/qbluetoothuuid.h>
 
+#include <QtGui/qguiapplication.h>
+#include <QtGui/qstylehints.h>
+
 #include <QtWidgets/qlistwidget.h>
 
+using namespace Qt::StringLiterals;
+
 RemoteSelector::RemoteSelector(const QBluetoothAddress &localAdapter, QWidget *parent)
     :   QDialog(parent), ui(new Ui::RemoteSelector)
 {
@@ -19,6 +24,10 @@ RemoteSelector::RemoteSelector(const QBluetoothAddress &localAdapter, QWidget *p
     setWindowState(Qt::WindowMaximized);
 #endif
 
+    QStyleHints *styleHints = qGuiApp->styleHints();
+    updateIcon(styleHints->colorScheme());
+    connect(styleHints, &QStyleHints::colorSchemeChanged, this, &RemoteSelector::updateIcon);
+
 //! [createDiscoveryAgent]
     m_discoveryAgent = new QBluetoothServiceDiscoveryAgent(localAdapter);
 
@@ -104,6 +113,14 @@ void RemoteSelector::discoveryFinished()
     ui->status->setText(tr("Select the chat service to connect to."));
 }
 
+void RemoteSelector::updateIcon(Qt::ColorScheme scheme)
+{
+    const QString bluetoothIconName = (scheme == Qt::ColorScheme::Dark) ? u"bluetooth_dark"_s
+                                                                        : u"bluetooth"_s;
+    const QIcon bluetoothIcon = QIcon::fromTheme(bluetoothIconName);
+    ui->iconLabel->setPixmap(bluetoothIcon.pixmap(24, 24, QIcon::Normal, QIcon::On));
+}
+
 void RemoteSelector::on_remoteDevices_itemActivated(QListWidgetItem *item)
 {
     m_service = m_discoveredServices.value(item);
@@ -116,6 +133,7 @@ void RemoteSelector::on_remoteDevices_itemActivated(QListWidgetItem *item)
 void RemoteSelector::on_remoteDevices_itemClicked(QListWidgetItem *)
 {
     ui->connectButton->setEnabled(true);
+    ui->connectButton->setFocus();
 }
 
 void RemoteSelector::on_connectButton_clicked()
diff --git a/examples/bluetooth/btchat/remoteselector.h b/examples/bluetooth/btchat/remoteselector.h
index e319caa6..6d5ba034 100644
--- a/examples/bluetooth/btchat/remoteselector.h
+++ b/examples/bluetooth/btchat/remoteselector.h
@@ -42,6 +42,7 @@ private:
 private slots:
     void serviceDiscovered(const QBluetoothServiceInfo &serviceInfo);
     void discoveryFinished();
+    void updateIcon(Qt::ColorScheme scheme);
     void on_remoteDevices_itemActivated(QListWidgetItem *item);
     void on_remoteDevices_itemClicked(QListWidgetItem *item);
     void on_cancelButton_clicked();
diff --git a/examples/bluetooth/btchat/remoteselector.ui b/examples/bluetooth/btchat/remoteselector.ui
index 108ae885..853f6105 100644
--- a/examples/bluetooth/btchat/remoteselector.ui
+++ b/examples/bluetooth/btchat/remoteselector.ui
@@ -15,31 +15,58 @@
   </property>
   <layout class="QVBoxLayout" name="verticalLayout">
    <item>
-    <widget class="QLabel" name="status">
+    <widget class="QLabel" name="iconLabel">
      <property name="text">
-      <string>Scanning...</string>
+      <string/>
+     </property>
+     <property name="alignment">
+      <set>Qt::AlignCenter</set>
      </property>
     </widget>
    </item>
    <item>
-    <widget class="QListWidget" name="remoteDevices"/>
-   </item>
-   <item>
-    <widget class="QPushButton" name="connectButton">
-     <property name="enabled">
-      <bool>false</bool>
-     </property>
+    <widget class="QLabel" name="status">
      <property name="text">
-      <string>Connect</string>
+      <string>Scanning...</string>
      </property>
     </widget>
    </item>
    <item>
-    <widget class="QPushButton" name="cancelButton">
-     <property name="text">
-      <string>Cancel</string>
-     </property>
-    </widget>
+    <widget class="QListWidget" name="remoteDevices"/>
+   </item>
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout">
+     <item>
+      <spacer name="horizontalSpacer">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+     <item>
+      <widget class="QPushButton" name="cancelButton">
+       <property name="text">
+        <string>Cancel</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QPushButton" name="connectButton">
+       <property name="enabled">
+        <bool>false</bool>
+       </property>
+       <property name="text">
+        <string>Connect</string>
+       </property>
+      </widget>
+     </item>
+    </layout>
    </item>
   </layout>
  </widget>