Author Archives: dmitriano

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21
12
22
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Touch target size on Android

Posted by | Android, QT |

Probably QT “Fusion” is not an appropriate style for Android apps, because its buttons height is not enough:

(more…)
19
12
22
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“One Edit Apart” task on Yandex interview

Posted by | C++ |

The task is to write one_edit_apart function that determines is it possible to make two given strings equal by replacing, adding or removing one symbol. The equal strings are considered to be equal, for example:

one_edit_apart("cat", "at") == true
one_edit_apart("cat", "cats") == true
one_edit_apart("cat", "cast") == true
one_edit_apart("cast", "cats") == false
one_edit_apart("cat", "cut") == true
one_edit_apart("cat", "dog") == false

The task is trivial, but Yandex interviewers require all the calculation to be done exactly in their inline editor without debugging and compiling and they do not accept the solution until it works for all possible input. The obvious solution is to truncate equal heads and equal tails and check if the lengths of remaining strings are not greater than 1, but if you forgot to handle the case when heads and tails intersect (with “a” and “aa”, for example) they will say “ooops…., you did a newbie mistake that 1-st year students usually do” and if this all takes more than 40 minutes you fail to pass the test. Below I provided the source code they are most likely to accept:

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11
12
22
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QT has Translation Rules for Plurals

Posted by | QT |

For example, there is the following content in qt-everywhere-src-6.4.1\qttranslations\translations\linguist_ru.ts:

<message numerus="yes">
    <source>Dropped %n message(s) which had no ID.</source>
    <translation>
        <numerusform>Удалено %n сообщение, у которого не было ID.</numerusform>
        <numerusform>Удалено %n сообщения, у которых не было ID.</numerusform>
        <numerusform>Удалено %n сообщений, у которых не было ID.</numerusform>
    </translation>
</message>
(more…)
11
12
22
 2 Comments

Building QT6.4.1 for Android on Windows

Posted by | QT |

Build QT6.4.1 for Windows and then build it for Android as follows:

set MY_DRIVE=D:

cd %MY_DRIVE%\dev\build\qta
%MY_DRIVE%
     
set "CMAKE_ROOT=%MY_DRIVE%\dev\tools\cmake-3.24.2-windows-x86_64\bin"
set "NINJA_ROOT=%MY_DRIVE%\dev\tools\ninja-win"
set "PERL_ROOT=%MY_DRIVE%\dev\tools\Strawberry\perl\bin"
set "MINGW_ROOT=%MY_DRIVE%\dev\tools\x86_64-12.2.0-release-win32-seh-rt_v10-rev0\mingw64\bin"
set "PYTHON_ROOT=%MY_DRIVE%\dev\tools\Python35"
set "JDK_ROOT=C:\Program Files\Android\Android Studio\jre\bin"
             
set PATH=C:\WINDOWS\system32;C:\WINDOWS
set PATH=%CMAKE_ROOT%;%PATH%
set PATH=%NINJA_ROOT%;%PATH%
set PATH=%MINGW_ROOT%;%PATH%
set PATH=%PERL_ROOT%;%PATH%
set PATH=%PYTHON_ROOT%;%PATH%
set PATH=%JDK_ROOT%;%PATH%
(more…)
10
12
22
 3 Comments

Building QT6.4.1 for Windows

Posted by | QT |

Extract QT sources:

cd /d/dev/repos
tar -xf ../distrib/qt-everywhere-src-6.4.1.tar.xz

Configure QT as follows:

"C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Auxiliary\Build\vcvarsall.bat" amd64

set MY_DRIVE=D:

%MY_DRIVE%

cd %MY_DRIVE%\dev\build\qt
   
set "CMAKE_ROOT=%MY_DRIVE%\dev\tools\cmake-3.24.2-windows-x86_64\bin"
set "NINJA_ROOT=%MY_DRIVE%\dev\tools\ninja-win"
set "PERL_ROOT=%MY_DRIVE%\dev\tools\Strawberry\perl\bin"
       
set PATH=%CMAKE_ROOT%;%PATH%
set PATH=%NINJA_ROOT%;%PATH%
set PATH=%PERL_ROOT%;%PATH%
set PATH=%MY_DRIVE%\dev\tools\Python35;%PATH%
(more…)
10
12
22
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Translation of standard buttons text on Android in QT6

Posted by | QT |

Found the following code in qt-everywhere-src-6.4.0\qtbase\src\plugins\platforms\android\qandroidplatformtheme.cpp:

QString QAndroidPlatformTheme::standardButtonText(int button) const
{
    switch (button) {
    case QPlatformDialogHelper::Yes:
        return QCoreApplication::translate("QAndroidPlatformTheme", "Yes");
    case QPlatformDialogHelper::YesToAll:
        return QCoreApplication::translate("QAndroidPlatformTheme", "Yes to All");
    case QPlatformDialogHelper::No:
        return QCoreApplication::translate("QAndroidPlatformTheme", "No");
    case QPlatformDialogHelper::NoToAll:
        return QCoreApplication::translate("QAndroidPlatformTheme", "No to All");
    }
    return QPlatformTheme::standardButtonText(button);
}
(more…)
17
11
22
 1 Comment

Key knowledge about forwarding references in C++

Posted by | C++ |

The compiler deduces U as std::string& or as std::string depending on value category of the argument:

template <class U>
void f(U&& s)
{
    static_assert(std::is_same_v<U, const std::string&>);

    std::cout << std::forward<U>(s) << std::endl;
}

int main()
{
    const std::string& s = "abc";

    f(s);

    return 0;
}
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02
11
22
 2 Comments

Creating Windows Application Icon on Ubuntu 22.04

Posted by | Ubuntu, Windows |

Install magick tool:

sudo apt update
sudo apt install imagemagick

Copy *.png files to a folder, for example:

win16x16.png
win32x32.png
win48x48.png
win64x64.png

and run the following command:

convert *.png winapp.ico
31
10
22
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QDebug can’t be used from a destructor of a static object

Posted by | QT |

We can’t do this in QT:

class Global
{
public:

    ~Global()
    {
        qDebug() << "Global destructor.";
    }
};

Global g;
(more…)
29
10
22
 2 Comments

QML Application Style

Posted by | QML, QT |

There was qtquickcontrols2.conf in the root directory of my app sources with the following content:

; This file can be edited to change the style of the application
; See Styling Qt Quick Controls 2 in the documentation for details:
; https://doc.qt.io/qt-6/qtquickcontrols2-styles.html

[Controls]
;Style=Default
;Style=Universal
;Style=Material
Style=Fusion
;Style=iOS

[Universal]
Theme=Light
Accent=Steel

[Material]
;Theme=Light
Theme=Dark
;Accent=BlueGrey
;Primary=BlueGray
(more…)
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