Change the preview by using wheel instead of just upgrading the scale twice.

Right clicking reset the position and the size.

linphone-app/ui/modules/Common/Helpers/DragBox.qml

@@ -19,6 +19,7 @@ Item {
 
   // ---------------------------------------------------------------------------
 
+  signal clicked (var mouse)
   signal pressed (var mouse)
   signal released (var mouse)
   signal wheel (var wheel)
@@ -57,7 +58,20 @@ Item {
       _mouseArea = null
     }
   }
+  function updateBoundaries(){
+        var container = dragBox.container
 
+        if (parent.x < 0) {
+          parent.x = 0
+        } else if (parent.x + parent.width >= container.width) {
+          parent.x = container.width - parent.width
+        }
+        if (parent.y < 0) {
+          parent.y = 0
+        } else if (parent.y + parent.height >= container.height) {
+          parent.y = container.height - parent.height
+        }
+  }
   // ---------------------------------------------------------------------------
 
   Component.onCompleted: enabled && _create()
@@ -81,11 +95,13 @@ Item {
 
       anchors.fill: parent
 
+      acceptedButtons: Qt.LeftButton | Qt.RightButton
+
       drag {
         axis: Drag.XandYAxis
         target: parent
       }
-
+      onClicked:dragBox.clicked(mouse)
       onPressed: {
         dragBox.pressed(mouse)
         held = true
@@ -94,20 +110,7 @@ Item {
       onReleased: {
         dragBox.released(mouse)
         held = false
-
-        var container = dragBox.container
-
-        if (parent.x < 0) {
-          parent.x = 0
-        } else if (parent.x + parent.width >= container.width) {
-          parent.x = container.width - parent.width
-        }
-
-        if (parent.y < 0) {
-          parent.y = 0
-        } else if (parent.y + parent.height >= container.height) {
-          parent.y = container.height - parent.height
-        }
+        updateBoundaries()
       }
 
       onWheel: dragBox.wheel(wheel)

linphone-app/ui/views/App/Calls/IncallFullscreenWindow.qml

@@ -422,7 +422,8 @@ Window {
       id: cameraPreview
 
       Camera {
-        property bool scale: false
+        id:cameraPreviewItem
+        property double scale: 1.0
 
         function xPosition () {
           return window.width / 2 - width / 2
@@ -431,12 +432,17 @@ Window {
         function yPosition () {
           return window.height - height
         }
+        
+        function resetPosition(){
+            x = xPosition ();
+            y = yPosition ();
+          }
 
         call: window.call
         isPreview: true
 
-        height: CallStyle.actionArea.userVideo.height * (scale ? 2 : 1)
-        width: CallStyle.actionArea.userVideo.width * (scale ? 2 : 1)
+        height: (CallStyle.actionArea.userVideo.height * window.height/CallStyle.actionArea.userVideo.heightReference) * scale
+        width: (CallStyle.actionArea.userVideo.width * window.width/CallStyle.actionArea.userVideo.widthReference) * scale 
 
         DragBox {
           container: window
@@ -444,8 +450,23 @@ Window {
 
           xPosition: parent.xPosition
           yPosition: parent.yPosition
+          
+          property double startTime: 0
 
-          onWheel: parent.scale = wheel.angleDelta.y > 0
+          onWheel: {
+                var acceleration = 0.1;
+                if(startTime == 0){
+                    startTime = new Date().getTime();
+                }else
+                    acceleration = Math.max(0.005,10/(new Date().getTime() - startTime));
+                parent.scale = Math.max(0.5 , parent.scale+acceleration*(wheel.angleDelta.y >0 ? 1 : -1) );
+                updateBoundaries();
+                startTime = new Date().getTime();
+          }
+          onClicked: if(mouse.button == Qt.RightButton) {
+                         parent.scale = 1;
+                         resetPosition();
+                    }
         }
       }
     }

linphone-app/ui/views/App/Styles/Calls/CallStyle.qml

@@ -19,6 +19,8 @@ QtObject {
     property QtObject userVideo: QtObject {
       property int height: 200
       property int width: 130
+      property int heightReference: 1200 // height and width are fixed from these references
+      property int widthReference: 780
     }
 
     property QtObject vu: QtObject {