QML downgrade from 6 to 5

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so many weird tricks that matter in Qt5 QML

1. the keyword “Window” is unrecongnized

You must type this line in the top of your qml file

import QtQuick.Window 2.3

or the keyword “Window” will be unrecongnized

2. all imported system libs will have their versions

//this is wrong
import QtQuick.Window

//this is correct
import QtQuick.Window 2.3

3. the way of the organization of qml in each project

qt5 use qmldir way to organize every qml module.

in qt6 qmldir is not created by coder it utlizes CMakelists.txt way to manage all qml files

4. qml individual module utilizes the folder name as its module name

e.g., module folder: folder_A folder content: a.qml b.qml qmldir the content of the qmldir:

module moduleA
a 1.0 a.qml
b 1.0 b.qml

now how to import in another certain c.qml file? the answer is

import folder_A 1.0

OMG, in qt6 everything has been organized in sub CMakelists.txt

### This file is automatically generated by Qt Design Studio.
### Do not change

###########################################################################################
# 9th
set_source_files_properties(SingletonModule/Exposes.qml PROPERTIES
    QT_QML_SINGLETON_TYPE TRUE
)

qt6_add_qml_module(SingletonModuleNamesssss
    URI "SingletonModuleName"
    VERSION 1.0
    QML_FILES
        SingletonFolder/a.qml
)



qt_add_library(content STATIC)
qt6_add_qml_module(content
    URI "content"
    VERSION 1.0
    RESOURCE_PREFIX "/qt/qml"
    QML_FILES
        main.qml        
    RESOURCES
        fonts/fonts.txt
        ../images/icons/g_icon.jpg
        ../images/icons/h_svg.svg
        ../images/icons/k_svg.svg
)

now how to import my singleton module which created by myself?

import SingletonModuleName 1.0

the URI is the key string so direct and simple without any confusion

but qt5, the mechanism is the import will cause engine to search the target folder with that exact name as we write with import keyword.

5. all qml files be put under qrc file defaultly

of course, you can choose not to manage them under qrc but this way is the default option

6. you must register the data type(s) if you wanna share data between cpp and qml

 qRegisterMetaType<data_type_a>("data_type_a");

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