Qt on Android: resource file system qrc and assets, androidqrc

Qt on Android: resource file system qrc and assets, androidqrc

When using Qt for Android development, sometimes our application carries some resource files, such as png and jpg, or some configuration files, such as xml, where are these files stored?

There are two methods:

Let's take a look.

The Qt Resource System

Qrc and Qt resource file systems are easy to use. See the figure:

Figure 1 qrc

Files you put in qrc, such as copy.png, will be compiled into the exe file (the Android Application is libapplication. so ). When you run an application, these resources are also loaded into the memory. If your resources are large, this is a problem.

On the Android platform, you have another option.

Android assets

There is an assets Directory In the Android project directory. The files in this directory will not be packaged into the APK. When the APK is installed on the Android system, the assets will not be installed in the application directory, it is still in APK, but the application can access resources in this folder!

Qt uses this mechanism to implement the assets Virtual File System. Common QFile, QPixmap, and QImage can all access files in assets through "assets.

With the assets Virtual File System, your resource files will not be loaded to the memory when the program starts, saving resources.

Look at a picture:

Figure 2 assets

How can I store resource files? Put it in the android/assets folder under the Qt project directory. 3:

Figure 3 use the directory structure of assets

As long as you put it in this way, the files in assets will be packaged into the APK during Qt compilation, and then they can be accessed in the C ++ code.

Android example using assets

Create a project for Android by referring to Qt on Android: full process of Hello World.

Create AndroidManifest. xml and place a beauty.jpg file in the android/assets Directory. Delete Widgets. h and widgets. cpp of the project. Modify main. cpp as follows:

#include <QApplication>#include <QLabel>#include <QPixmap>int main(int argc, char *argv[]){    QApplication a(argc, argv);    QLabel label;    QPixmap pixmap("assets:/beauty.jpg");    label.setPixmap(pixmap);    label.show();    return a.exec();}

Compile and run. You can see Figure 4:

Figure 4 Qt on Android example using assets

OK. The end is now.

Let's review the Qt on Android series:

Qt on Android: full process of Hello World

Introduction to Qt 5.2 for Android development in Windows

Analysis of the deployment process of Qt for Android

Qt on Android: Output Qt debugging information to logcat.

Qt on Android: Qt 5.3.0 released. Improvements for Android

Qt on Android Episode 1)

Qt on Android Episode 2)

Qt on Android Episode 3)

Qt on Android Episode 4)

Compiling a pure C project using Qt for Android

Compiling Android C language executable programs using Qt for Android in Windows

Qt on Android: Android SDK Installation

Qt on Android: http download and Json Parsing

Set the app name for Qt on Android to Chinese

Qt on Android: Enables full screen display of Qt Widgets and Qt Quick apps

Qt on Android: how to adapt to different screen sizes

Qt on Android: Use JNI and third-party jar packages

Introduction to Qt on Android core programming