screencapture example: Make the screen model dynamic

Use QGuiApplication::screens() to obtain the screens and
connect the changed signals to model reset. Make the description
a bit more verbose.

Change-Id: I92c0be712196aa7be475c08305ef6f8a20e603d3
Reviewed-by: Lars Knoll <lars@knoll.priv.no>
Reviewed-by: Artem Dyomin <artem.dyomin@qt.io>
(cherry picked from commit 004c18bb572329778a3e85fe436e0b216cf1f287)

4 files changed, 29 insertions, 15 deletions

diff --git a/examples/multimedia/screencapture/screencapturepreview.cpp b/examples/multimedia/screencapture/screencapturepreview.cpp
index 728e89220..9f40c8c80 100644
--- a/examples/multimedia/screencapture/screencapturepreview.cpp
+++ b/examples/multimedia/screencapture/screencapturepreview.cpp
@@ -21,7 +21,6 @@ ScreenCapturePreview::ScreenCapturePreview(QWidget *parent)
     : QWidget(parent),
       screenListView(new QListView(this)),
       screenCapture(new QScreenCapture(this)),
-      screens(QGuiApplication::screens()),
       mediaCaptureSession(new QMediaCaptureSession(this)),
       videoWidget(new QVideoWidget(this)),
       gridLayout(new QGridLayout(this)),
@@ -30,8 +29,7 @@ ScreenCapturePreview::ScreenCapturePreview(QWidget *parent)
       videoWidgetLabel(new QLabel("QScreenCapture output:", this))
 {
     // Get list of screens:
-    screenListModel = new ScreenListModel(screens, this);
-    qDebug() << "return value from QGuiApplication::screens(): " << screens;
+    screenListModel = new ScreenListModel(this);
 
     // Setup QScreenCapture with initial source:
 
diff --git a/examples/multimedia/screencapture/screencapturepreview.h b/examples/multimedia/screencapture/screencapturepreview.h
index 72b639639..da665ab08 100644
--- a/examples/multimedia/screencapture/screencapturepreview.h
+++ b/examples/multimedia/screencapture/screencapturepreview.h
@@ -38,7 +38,7 @@ private:
     ScreenListModel *screenListModel = nullptr;
     QListView *screenListView = nullptr;
     QScreenCapture *screenCapture = nullptr;
-    QList<QScreen *> screens;
+    QWindowList windows;
     QMediaCaptureSession *mediaCaptureSession = nullptr;
     QVideoWidget *videoWidget = nullptr;
     QGridLayout *gridLayout = nullptr;
diff --git a/examples/multimedia/screencapture/screenlistmodel.cpp b/examples/multimedia/screencapture/screenlistmodel.cpp
index 6a3a1efd7..0b46560cc 100644
--- a/examples/multimedia/screencapture/screenlistmodel.cpp
+++ b/examples/multimedia/screencapture/screenlistmodel.cpp
@@ -3,28 +3,38 @@
 
 #include "screenlistmodel.h"
 
+#include <QGuiApplication>
 #include <QScreen>
 
-ScreenListModel::ScreenListModel(const QList<QScreen *> &data, QObject *parent) :
-      QAbstractListModel(parent),
-      screenList(data)
+#include <QTextStream>
+
+ScreenListModel::ScreenListModel(QObject *parent) :
+      QAbstractListModel(parent)
 {
+    auto *app = qApp;
+    connect(app, &QGuiApplication::screenAdded, this, &ScreenListModel::screensChanged);
+    connect(app, &QGuiApplication::screenRemoved, this, &ScreenListModel::screensChanged);
+    connect(app, &QGuiApplication::primaryScreenChanged, this, &ScreenListModel::screensChanged);
 }
 
 int ScreenListModel::rowCount(const QModelIndex &) const
 {
-    return screenList.size();
+    return QGuiApplication::screens().size();
 }
 
 QVariant ScreenListModel::data(const QModelIndex &index, int role) const
 {
+    const auto screenList = QGuiApplication::screens();
     Q_ASSERT(index.isValid());
     Q_ASSERT(index.row() <= screenList.size());
 
     if (role == Qt::DisplayRole) {
-        auto screen = screenList.at(index.row());
-        return QString("%1: %2").arg(screen->metaObject()->className(),
-                                     screen->name());
+        auto *screen = screenList.at(index.row());
+        QString description;
+        QTextStream str(&description);
+        str << '"' << screen->name() << "\" " << screen->size().width() << 'x'
+            << screen->size().height() << ", " << screen->logicalDotsPerInch() << "DPI";
+        return description;
     }
 
     return {};
@@ -32,7 +42,13 @@ QVariant ScreenListModel::data(const QModelIndex &index, int role) const
 
 QScreen *ScreenListModel::screen(const QModelIndex &index) const
 {
-    return screenList.at(index.row());
+    return QGuiApplication::screens().value(index.row());
+}
+
+void ScreenListModel::screensChanged()
+{
+    beginResetModel();
+    endResetModel();
 }
 
 #include "moc_screenlistmodel.cpp"
diff --git a/examples/multimedia/screencapture/screenlistmodel.h b/examples/multimedia/screencapture/screenlistmodel.h
index 83cc1e664..3bfa30b8f 100644
--- a/examples/multimedia/screencapture/screenlistmodel.h
+++ b/examples/multimedia/screencapture/screenlistmodel.h
@@ -17,14 +17,14 @@ class ScreenListModel : public QAbstractListModel
     Q_OBJECT
 
 public:
-    explicit ScreenListModel(const QList<QScreen *> &data, QObject *parent = nullptr);
+    explicit ScreenListModel(QObject *parent = nullptr);
 
     int rowCount(const QModelIndex &parent = QModelIndex()) const override;
     QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
     QScreen *screen(const QModelIndex &index) const;
 
-private:
-    QList<QScreen *> screenList;
+private Q_SLOTS:
+    void screensChanged();
 };
 
 #endif // SCREENLISTMODEL_H