Develop Reference

Taking Screenshots Using Qt C++ on Android

thanks for checking my question out!
I'm currently working on a project using Qt C++, which is designed to be multi-platform. I'm a bit of a newcoming to it, so I've been asked to set up the ability to take screenshots from within the menu structure, and I'm having issues with the Android version of the companion app.
As a quick overview, it's a bit of software that send the content of a host PC's screen to our app, and I've been able to take screenshots on the Windows version just fine, using QScreen and QPixmap, like so:
overlaywindow.cpp
{
QPixmap screenSnapData = screenGrab->currentBackground();
}
screenGrabber.cpp
{
QScreen *screen = QGuiApplication::primaryScreen();
return screen->grabWindow( QApplication::desktop()->winId() );
}
Unfortunately, Android seems to reject QScreen, and with most suggestions from past Google searches suggesting the now-deprecated QPixmap::grab(), I've gotten a little stuck.
What luck I have had is within the code for the menu itself, and QWidget, but that isn't without issue, of course!
QFile doubleCheckFile("/storage/emulated/0/Pictures/Testing/checking.png");
doubleCheckFile.open(QIODevice::ReadWrite);
QPixmap checkingPixmap = QWidget::grab();
checkingPixmap.save(&doubleCheckFile);
doubleCheckFile.close();
This code does take a screenshot, but only of the button strip currently implemented, and not for the whole screen. I've also taken a 'screenshot' of just a white box with the screen's dimensions by using:
QDesktopWidget dw;
QWidget *screen=dw.screen();
QPixmap checkingPixmap = screen->grab();
Would anyone know of whether there was an alternative to using QScreen to take a screenshot in Android, or whether there's a specific way to get it working as compared to Windows? Or would QWidget be the right track? Any help's greatly appreciated!

as i can read in Qt doc : In your screenGrabber.cpp :
QScreen *screen = QGuiApplication::primaryScreen();
return screen->grabWindow( QApplication::desktop()->winId() );
replace with :
QScreen *screen = QGuiApplication::primaryScreen();
return screen->grabWindow( 0 ); // as 0 is the id of main screen

If you want to take a screenshot of your own widget, you can use the method QWidget::render (Qt Doc):
QPixmap pixmap(widget->size());
widget->render(&pixmap);
If you want to take a screenshot of another app/widget than your app, you should use the Android API...

masked input not working in android mobiles?

I am using the digitalbush masked input jQuery plugin. It is working fine in web browsers and the iPhone browser perfectly, but it is not working for Android mobile devices.
My issue :
mask is
in input field _ - _ - ___.
When I type numbers it will 12345685555___--
Example: http://rossbender.com/temp/mask.html
Any suggestions? How can I solve this?
Thanks
Prasad.

I resolved this issue with three actions, which have fixed this for all Android 4.0+ phones:
Update masked-input to at least version 1.4
Add type="tel" to the input, to trigger the numeric keyboard
Remove the input's maxlength attribute or set it to a value certain not to interfere with the caret action, like 20.

I tried using the raw script that Jonathan Rowny mentioned, but I was still having the same problem on an S3 - Chrome browser. I think it has something to do with inputs type="tel" and/or type="number". I ended up having to use another plugin. http://igorescobar.github.io/jQuery-Mask-Plugin/
jquery-mask (not to be confused with jquery-masked-input) is very similar but the syntax was slightly different. Hope this helps anyone else with this issue.
jquery-masked-input syntax:
$("#phone").mask("(999) 999-9999");
VS
jquery-mask syntax: ('#phone').mask('(000) 000-0000');

This was fixed awhile ago but for some reason the distribution posted on the website never took the changes. If you grab from the raw source, the fix works: https://raw.githubusercontent.com/digitalBush/jquery.maskedinput/master/src/jquery.maskedinput.js

After trying different mask libraries (Inputmask, ui-mask, ngMask) I ended up using jQuery-Mask-Plugin https://igorescobar.github.io/jQuery-Mask-Plugin/ which works pretty well and is also lightweight and well documented and has angularjs, react ,... samples.

I just ran into this problem and resolved it by removing the attribute type="number" from the asp textbox. After that masked input worked even on mobile devices.

The library used in the question is no longer being maintained. I switched my application to jQuery Mask Input as it works great, has a very similar base init call to the former library making for an extremely easy transition and, at the time of this post, jQuery Mask Input is regularly maintained at GitHub.
My issue was with the phone number masker moving the cursor back to the second position when 3 or 4 digits were entered. The cursor continued to act odd after that point. The problem was noticed using jQuery Masked Input v1.4.1 (old library) in android tablets using Chrome post major version 51.

To further enhance the accepted answer of Tony Brasunas, add following snippet in jquery.maskedinput.js for point number 3 to dynamically increase maxlength so it doesn't interfere with caret action.
Remove the input's maxlength attribute or set it to a value certain not to interfere with the caret action, like 20.
defs = $.mask.definitions;
tests = [];
partialPosition = len = mask.length;
firstNonMaskPos = null;
//insert snippet below
if (chrome && android) {
console.log("chrome && android");
var allAllowedRegExps = '';
jQuery.each(defs, function (key, value) {
allAllowedRegExps = allAllowedRegExps + key;
});
allAllowedRegExps = allAllowedRegExps.replace(/\[/g, '');
allAllowedRegExps = allAllowedRegExps.replace(/\]/g, '');
allAllowedRegExps = '[^' + allAllowedRegExps + ']';
var re = new RegExp(allAllowedRegExps, "g");
var actual = mask;
var replacedVal = actual.replace(re, "");
var actualValue = actual.length - replacedVal.length;
if ($(this).attr('maxlength') !== undefined) {
$(this).attr('maxlength', parseInt(this.attr('maxlength')) + parseInt(actualValue));
}
}
mask = String(mask);

This can be a quick fix:
var ua = navigator.userAgent;
var isAndroid = /Android/i.test(ua);
var isChrome = /Chrome/i.test(ua);
// Fix masking on Chrome for mobile devices
if (isAndroid && isChrome) {
$('.price_input').attr('type','tel');
}

It worked for me by using 1.4.1 and setting the max length to one plus the number of chars in the mask. The mask limited the actual input and the max length +1 fixed the problem of not being able to type numbers in the field.

Same Titanium code base for Android & Iphone

I have been trying to create a single codebase for both Iphone & Android for a intermediate level app. ( 4 tabs, multiple windows, maps etc.) using itanium 2.1 API.
However, I have found that things on Android platform dont work as smoothly or willingly as on Iphone epsecially tableviews & UI elemnts. The UI responsiveness on Android is also sluggish.
The kitchen sink examples are pretty straightforward. I am looking at an enterprise ready app which has to be maintained for atleast next couple of years.
Has anybody worked on similar lines with platform quirks and been successful in creating fully functional iOS & Android apps from SAME codebase?

I'm having a lot of success using the compile-time CommonJS mechanism for having a root view that then has os-specific capabilities.
For instance, my os-independent view might be ui/MyView.js :
var createAddButton = require("ui/MyView.AddButton");
var MyView = function() {
var self = Ti.UI.createWindow();
createAddButton(self, function() { alert('ADD!'); });
return self;
};
module.exports = MyView;
Then, I create os-specific functions to handle it:
iphone/ui/MyView.AddButton.js
module.exports = function(view, addHandler) {
var addButton = Titanium.UI.createButton({
systemButton: Titanium.UI.iPhone.SystemButton.ADD
});
addButton.addEventListener("click", addHandler);
view.rightNavButton = addButton;
};
android/ui/MyView.AddButton.js
module.exports = function(view, addHandler) {
view.activity.onCreateOptionsMenu = function(e){
var menuItem = e.menu.add({ title: "Add" });
menuItem.addEventListener("click", addHandler);
};
};
The CommonJS system they have implemented will pick the appropriate version of MyView.AddButton.js so that the button is added to the right place. It allows for the majority of the view to be the same, but the os-specific things to be separated properly.

Titanium is not meant for 1 codebase for all. You do need to rewrite stuff for every OS. However, some app developers claim to have reused 95% of its code. So only 5% of the code is OS specific. But I am sure their code is full with if-elses.
What I recommend doing, to be able to maintain it properly, without thousands of if-else constructions, is build a single backend core, and write code specifically for UI related matters per OS. This way, you have some UI related code for Android, UI related code for iOS and 1 core working for both.
Since Android and iOS differ a lot, writing a single codebase will make sure you can never use OS specific features (like android hardware menu button, or iOS NavigationGroup), and will let the UI look non-intuitive.

How to import a SpriteFont into MonoGame

I'm porting a simple tetris-like XNA app to Android, using Mono For Android and MonoGame; I have followed the suggested steps in this link and so far, everything compiles well, and no relevant warnings fire up. However, upon loading the contents, a null parameter exception breaks the program at the point below in my program:
protected override void LoadContent() {
// ...
_font = Content.Load<Microsoft.Xna.Framework.Graphics.SpriteFont>("SpriteFont1");
// ...
}
The content root directory is set in the game constructor class:
public Game2 (){
Content.RootDirectory = "Content";
Content.RootDirectory = "Assets/Content"; // TEST.
//...}
And I have tried several combinations, all to no avail.
I have also tried setting the xnb files as Content as well as Android Assets in the Build Action property; having the linked, copied always, copied only if newer... etc.
Either way, my problem is that I don't really understand WHY and HOW should I do this. I'm rather new to the platform and to XNA as well, so this may very well be a newbie question, but the truth is after several hours banging my head and fists against the monitor/keyboard I feel stuck and need your help.

I have a library that supports variable-width fonts (generated by BMFont) on MonoGame. Unfortunately it is a renderer and so has other code around it. However, the basic idea is very simple. You can take a look at the loader here and the mesh builder (given a string) here. This builder supports fonts that spread characters across multiple pages, too.
Hope this helps!

MonoGame (2.5.1) throws NotImplementedException in ContentManager.Load for SpriteFont type. Have the same not resolved problem. I'm trying not to use DrawString.
For loading textures in Win32 application I use:
Content.RootDirectory = #"../../Content";
var sampleTexture = Content.Load<Texture2D>("Sample.png");
You even must not add it to solution.
For Andoind (MonoDroid) application you must add "Content" folder to your solution and set "Andtoid Asset" in "Sample.png" properties.
Content.RootDirectory = "Content";
var sampleTexture = Content.Load<Texture2D>("Sample.png");
See also:
http://monogame.codeplex.com/discussions/360468
http://monogame.codeplex.com/discussions/267900

How to practically display math formula in Android

I researched on this for quite a while and I know this kind of questions already answered. But I couldn't find a right answer showing how to practically deal with math formula in Android app. Without including large amount (5~20MB) of files in the Android project, it seems that there is no way to parse & display math formula script like MATHML. I looked at JEuclid and MathJax that were mentioned a lot for Android but I found them in this category.
So at this point, the only way I can think of is to take each of those formula in a image file and display it on Android. But in practice, that manual process is really slow. I am sure this is not a right way.
So I have to ask this again. How to practically display math formula in your Android app?

You can not set maths formula to TextView in android. You have to use WebView in which you can display maths formulae. See mathjax for more information.
if you want to display for android then here is library you can implement in your project. mathjaxwebview

If you want to parse Tex(Inline mode and display mode) formats and ASCII math format you can use this link .I used the above math view given in this link to display formula.It worked like a charm adding to that download mathjax from official site and get fonts folder and put it in your assets folder. It will definitely work.
https://github.com/Nishant-Pathak/MathView
download math view form above link.

The libraries which are using WebView to wrap latex-rendering-js-library (e.g., this, this and this), are not working well with the RecyclerView and will make the app slow. And they are not even updating the js libraries.
Finally, I found "noties/jlatexmath-android", which is using "opencollab/jlatexmath" native Java library. It is fast and can be easily used with RecyclerView.
Sample usage of JLatexMathView:
implementation "ru.noties:jlatexmath-android:$jlatexmath_version"
// for Cyrillic symbols
implementation "ru.noties:jlatexmath-android-font-cyrillic:$jlatexmath_version"
// for Greek symbols
implementation "ru.noties:jlatexmath-android-font-greek:$jlatexmath_version"
<ru.noties.jlatexmath.JLatexMathView
android:id="#+id/j_latex_math_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="16dip"
android:background="#color/white"
app:jlmv_alignVertical="center"
app:jlmv_alignHorizontal="center"
app:jlmv_textSize="16sp" />
val latexText = "\$\$f(x)=(x+a)(x+b)\$\$"
binding.jLatexMathView.setLatex(latexText)
You can also use it as an extension of "noties/Markwon", a Markdown library for Android. Details can be found here.
Sample Usage of Markwon:
implementation "io.noties.markwon:core:$markwon_version"
implementation "io.noties.markwon:ext-latex:$markwon_version"
implementation "io.noties.markwon:inline-parser:$markwon_version"
<TextView
android:id="#+id/tv_markdown"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
val markwon = Markwon.builder(requireContext())
.usePlugin(MarkwonInlineParserPlugin.create())
.usePlugin(JLatexMathPlugin.create(binding.tvMarkdown.textSize) { builder ->
// ENABLE inlines
builder.inlinesEnabled(true)
})
.build()
val latexText = "Example: \$\$f(x)=(x+a)(x+b)\$\$"
markwon.setMarkdown(binding.tvMarkdown, latexText)

You can implement with MathType.
But your data for display must be in MathType format
https://docs.wiris.com/en/mathtype/mathtype_web/sdk/mobile-apps