I have an Android QT app with more than has 14K active users at the moment of writing this post. The app is relatively stable, its crash rate is 0.34%:
Category Archives: Platforms and frameworks
Adding interstitial ads to a QT application on Android platform
I keep working on my Lines Game and probably I try to make it the best Lines Game in the world, but there is some disappointing incident that prevents it from being the best and makes it a usual game that glitches a bit. To see the glitch in action download the beta version of the game.
Adding Interstitial Ads to a QT application on Android platform is an interesting and relatively exciting job. I learned the following facts while doing it:
- To build my app with Google Play Services I add com.google.android.gms:play-services-ads:18.1.1 dependency to build.gradle and add com.google.android.gms.version and com.google.android.gms.ads.APPLICATION_ID to the manifest.
- I do not specify additional permissions (uses-permission attributes INTERNET, WRITE_EXTERNAL_STORAGE, ACCESS_NETWORK_STATE) required by ads, but they are detected automatically when I upload the app to Google Play store and the used is not prompted to allow them when the app starts.
- QT main thread (on which QML UI is run) is not Android UI thread. So I cannot call Java advertising API from QML or C++ directly, but all the calls should be queued with runOnUiThread method.
- To access Context required by Java advertising API I replace QtActivity with my own custom activity that implements all the advertising logic and forwards all the lifecycle events to original QtActivity.
- When the interstitial ad is open my activity is paused and stopped (onPaused / onStopped event handlers are called in Java and onApplicationStateChanged with Qt::ApplicationInactive / Qt::ApplicationSuspended respectively ) and when the interstitial ad is closed my activity is resumed but in different ways either with onRestart.
Compiling OpenSSL 1.1 with MSVC2017 for using with QT 5.13
QT does not work with OpenSSL 1.0 anymore. Versions QT 5.12.4 and above require OpenSSL 1.1, but fortunately OpenSSL 1.1 can be easily compiled with MS2017 as follows:
set PATH=%PATH%;C:\Perl64\bin
set PATH=%PATH%;C:\PFiles\nasm-2.14.02-win64
perl Configure VC-WIN64A
nmake
The key to the success is using ‘VS2017 x64 Native Tools Command Prompt‘, but not ‘VS2017 Developer Command Prompt’.
To make QT use OpenSSL, two dlls
libcrypto-1_1-x64.dll
libssl-1_1-x64.dll
should be copied to QT binary directory, for example, C:\Qt\Qt5.13.0\5.13.0\msvc2017_64\bin
Determining .NET Framework version from the native C++ code.
.NET Framework version 4.5 and higher can be determined with the following C++ code:
#include <windows.h>
bool IsDotNet45Installed()
{
DWORD value{};
DWORD dataSize = sizeof(value);
const LONG retCode = ::RegGetValue(
HKEY_LOCAL_MACHINE,
L"SOFTWARE\\Microsoft\\NET Framework Setup\\NDP\\v4\\Full\\",
L"Release",
RRF_RT_REG_DWORD,
nullptr,
&value,
&dataSize
);
if (retCode != ERROR_SUCCESS)
{
return false;
}
return value >= 378389;
}
How I built QT 5.11.1 for Android on Windows
I tried to build QT 5.11.1 for Android on Windows, and “configure.bat” completed successfully, but “mingw32-make” failed with with the following error:
No rule to make target 'vulkan/qvulkanfunctions_p.h', needed by '.obj\qvulkaninstance.obj'.
It is the bug fixed in QT 5.11.2 that is planned on August/September 2018.
When I build the master branch and copied the following files from it to \qtbase\src\gui\vulkan manually:
qvulkanfunctions.h qvulkanfunctions_p.cpp qvulkanfunctions_p.h
and started “mingw32-make” again I got another error:
How I compiled OpenSSL from sources with VS2015
I installed Perl, downloaded and extracted OpenSSL 1.1.0h and built 64 bit version in VS2015 x64 Native Tools Command Prompt with the following commands:
set PATH=%PATH%;C:\Perl64\bin perl Configure VC-WIN64A no-asm nmake
32 bit version can be built with VC-WIN32 configuration option as described in INSTALL:
on Windows (only pick one of the targets for configuration):
$ perl Configure { VC-WIN32 | VC-WIN64A | VC-WIN64I | VC-CE }
$ nmake
$ nmake test
$ nmake install
probably ‘A’ suffix means AMD and ‘I’ means something else, so we need ‘A’.
Regular expressions for editing DEF-file (Windows Module-Definition file)
The following regular expression (find/replace pair) in Visual Studio format removes extra whitespace and @ symbol from a DEF-file:
^[ \t]+(\b(?<name>_\w+|[\w-[0-9_]]\w*)\b)[ \t]+@(?<index>\d+)(?=\r?$)
${name}\t${index}
and converts it to such a form when it can be imported to MS Excel and sorted by the function number, so you can manually add new functions by incrementing the last number.
To convert the file back the following find/replace pair can be used:
^(\b(?<name>_\w+|[\w-[0-9_]]\w*)\b)[ \t](?<index>\d+)(?=\r?$)
\t${name}\t\t@${index}
Setting up QT Creator 4.6.1 for Android development on Windows 10
First I installed Android Studio. When it started I set an option to create the application with Native C++ support and Android NDK was automatically installed to C:\Users\AppData\Local\Android\Sdk\ndk-bundle, also I added Android-19 API level and somehow CMake was installed to C:\Users\AppData\Local\Android\Sdk\cmake\3.6.4111459. Then in QT Creator I opened Tools->Options->Devices->Android and specified the following paths:
Building QT 5.10.1 from sources with VS2017
I am not sure it is a correct way, but I was able to do this:
git clone --recursive https://code.qt.io/qt/qt5.git --branch v5.10.1
and all the submodules were checked out with commit hashes tag v5.10.1 points to:
You are in 'detached HEAD' state. You can look around, make experimental changes and commit them, and you can discard any commits you make in this state without impacting any branches by performing another checkout. ... Submodule path 'qt3d': checked out '31f424bb81cd2583920d3d521e1e01f01c2d28e2' ...
Generating .NET wrappers for COM during build in MS Visual Studio
If in some Visual Studio solution a .NET project references a C++ project that implements a COM server then the following command can be used in Post-Build Event of the C++ project to generate .NET wrapper for COM:
"$(TargetFrameworkSDKToolsDirectory)tlbimp.exe" "$(TargetPath)" /verbose /strictref /asmversion=$(Version) /out:"$(TargetDir)$(TargetName)Lib.dll"
In VS2015 by default this command will generate .NET 4.0 assembly. To generate .NET 2.0 assembly, the following command can be used:
"C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Bin\TlbImp.exe" "$(TargetPath)" /verbose /strictref /asmversion=$(Version) /out:"$(TargetDir)$(TargetName)Lib.dll"
I am not sure that changing TargetFrameworkVersion attribute in PropertyGroup Label=”Globals” element of the project file can help here, so it is not clear how to get rid of absolute path.
Also it is impossible to add a reference to a TLB or EXE file to .NET assembly, so using TLB generated by MIDL directly is not an option (MIDL->Output page of C++ project using $(OutDir)$(TargetName).tlb as Type Library name).
