Hi,
Using this example, firstly, I created an "Application > Qt Quick application project".
I didn't change the main.cpp and kept the Window part and entered the Rectangle section below that, as follows:

Qt Code: 
  1. ```
  2. import QtQuick 2.6
  3. import QtQuick.Window 2.2
  4.  
  5. Window {
  6.     visible: true
  7.     width: 640
  8.     height: 480
  9.     title: qsTr("Rec")
  10.  
  11.    Rectangle {
  12.       id: root
  13.       x: 50; y: 10
  14.        width: 120; height: 240
  15.        color: "Blue"
  16.  
  17.        Image {
  18.            id: triangle
  19.            x: root.width + width/2; y: height/2
  20.            source: "/triangle_red.png"
  21.        }
  22.  
  23.        Text {
  24.            y: 50
  25.            width: root.width
  26.            color: "white"
  27.            horizontalAlignment: Text.AlignHCenter
  28.            text: "Triangle"
  29.        }
  30.    }
  31. }
  32. ```
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The output is shown for Desktop. For other kits I just pressed the build button because I just needed the APK files.

My questions:

1- Is the type of the project I created exactly the one the book has used?
2-Do I need to keep the Window section? If so why isn't it shown in the example?
3- Shouldn't I change anything in main.cpp?
4- I built the project using the Arm Android kit but the size of the APK files for both Release and Debug modes are the same. I expected to have a smaller size for the Release mode.

Thank you.