floui-rs

Rust bindings for floui, pronounced "flowy", a proof-of-concept single header C++17 lib inspired by SwiftUI, which wraps native iOS and Android controls/widgets, and integrates into the de facto build environments of each platform (XCode and Android Studio).

Currently available controls:

• Text
• TextField
• Button
• VStack (Vertical UIStackView on iOS and LinearLayout on Android)
• HStack (Horizontal UIStackView on iOS and LinearLayout on Android)
• Spacer
• Toggle/Check (tvOS doesn't support it)
• Slider (tvOS doesn't support it)
• ImageView
• WebView
• ScrollView

Usage

You can check out the floui-rs-template, which is structured to be able to build for both ios or android from the command-line.

Otherwise, if you would like to do it manually:

Build your library as a static-lib: ```toml

Cargo.toml

[lib] crate-type = ["static-lib"]

[dependencies] floui = "0.1" ``` Build against the android and ios architectures you might need.

Rust

```rust use floui::{enums::, prelude::, widgets::*}; use std::cell::RefCell; use std::rc::Rc;

fn mygui(vc: &ViewController) -> MainView { let count = Rc::from(RefCell::from(0)); MainView::new( &vc, &[ &Button::new("Increment").foreground(Color::Blue).action({ let count = count.clone(); move || { log("Increment clicked"); let mut c = count.borrowmut(); *c += 1; let t: Text = fromid("mytext").unwrap(); t.text(&format!("{}", c)); } }), &Text::new("0").id("mytext").center().bold(), &Button::new("Decrement") .foreground(Color::Red) .action(move || { log("Increment clicked"); let mut c = count.borrowmut(); *c -= 1; let t: Text = fromid("mytext").unwrap(); t.text(&format!("{}", c)); }), ], ) }

use std::os::raw::c_void;

[no_mangle]

extern "C" fn flouihandleevents(arg1: *mut cvoid) { unsafe { ViewController::handleevents(arg1); } }

[no_mangle]

extern "C" fn flouimain(arg1: *mut cvoid, arg2: *mut cvoid, arg3: *mut cvoid) -> *mut c_void { let vc = unsafe { ViewController::new(arg1, arg2, arg3) }; mygui(&vc).underlying() as _ } ```

Notes on certain usages

• Sliders on Android take the full width of the LinearLayout, so this must be taken into consideration if code is shared also with iOS.

• Adding images has to be in the project's resource file.

  • In Android Studio: Resource Manager, Import Drawables. This will add the file to res/drawable. The file can be accessed directly ImageView::load("MyImage.jpg").
  • In XCode: You can simply drag images into Assets.xcassets, then the image can be accessed directly ImageView::load("MyImage.jpg").

• Using the WebView widget

  • on iOS:
    • Requires adding WebKit.framework under General > Frameworks, Libraries and Embedded Content.
    • Requires enabling the ios-webview flag in your Cargo.toml.
    • Local files can be loaded using WebView::load_url() but need to be preceded by file:///, the files should be added to your xcode project.
  • On Android:
    • To load local files, precede them with file:/// and the path of the file, which should be added to an assets folder (File > New > Folder > Assets folder). This then can be loaded using WebView::load_url().
    • To load http requests, you need to enable the internet permission in your AndroidManifest.xml: <uses-permission android:name="android.permission.INTERNET" />

Creating new widgets

Wrapping platform widgets doesn't require using C++, it requires that the widget implements WidgetExt, and the underlying (JNI jobject pointer for Android, UIView on iOS) can be retrieved. You can use the jni-rs crate and objc crates for such purposes.

Target-specific structure

iOS

• Add the required ios rustup targets.
• Install cargo-lipo.
• Add the built library to your xcode project (under Build Phases > Link Binary with Libraries).
• Modify the library search path to find the library (under Build Settings > Library Search Paths).
• Modify your ViewController.m file: ```objc

  import "ViewController.h"

extern void *floui_main(void *, void *, void *);

@interface ViewController ()

@end

@implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; floui_main((void *)CFBridgingRetain(self), nil, nil); }

@end ```

Android

• ANDROIDSDKROOT should be set to your android sdk directory.
• ANDROIDNDKROOT should be set to your android ndk directory.
• Add the required android rustup targets.
• Create an Android Studio Native C++ project, choose toolchain C++ 17 in the last step.
• Modify your CMakeLists.txt: ```cmake cmakeminimumrequired(VERSION 3.4.1) project(myapplication)

find_library(log-lib log)

addlibrary(myapplication SHARED native-lib.cpp) addlibrary(rust-lib STATIC IMPORTED)

if (ANDROIDABI STREQUAL x86) set(RUSTARCH i686-linux-android) elseif (ANDROIDABI STREQUAL armeabi-v7a) set(RUSTARCH armv7-linux-androideabi) elseif (ANDROIDABI STREQUAL arm64-v8a) set(RUSTARCH aarch64-linux-android) elseif (ANDROIDABI STREQUAL x8664) set(RUSTARCH x8664-linux-android) else () message(FATAL "Unknown architecture") endif ()

setproperty(TARGET rust-lib PROPERTY IMPORTEDLOCATIONDEBUG ${CMAKECURRENTLISTDIR}/app/target/${RUSTARCH}/debug/libapp.a) setproperty(TARGET rust-lib PROPERTY IMPORTEDLOCATIONRELEASE ${CMAKECURRENTLISTDIR}/app/target/${RUSTARCH}/release/libapp.a)

targetlinklibraries(myapplication android rust-lib ${log-lib}) - Modify your C++ file to just call the Rust lib. c++

include

include

extern "C" void *floui_main(void *, void *, void *);

extern "C" void flouihandleevents(void *);

extern "C" JNIEXPORT jobject JNICALL JavacomexamplemyapplicationMainActivitymainView(JNIEnv* env, jobject mainactivity, jobject view) { return (jobject) flouimain(env, mainactivity, view); }

extern "C" JNIEXPORT void JNICALL JavacomexamplemyapplicationMainActivityhandleEvent(JNIEnv *env, jobject thiz, jobject view) { flouihandle_events(view); } - Modify your MainActivity.java to look like: java package com.example.myapplication;

import androidx.annotation.NonNull; import androidx.appcompat.app.AppCompatActivity; import androidx.constraintlayout.widget.ConstraintLayout;

import android.os.Bundle; import android.view.View;

import com.google.android.material.slider.Slider;

public class MainActivity extends AppCompatActivity implements View.OnClickListener, Slider.OnChangeListener { static { System.loadLibrary("myapplication"); }

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ConstraintLayout layout = new ConstraintLayout(this);
    setContentView(layout);
    mainView(layout);
}
public native View mainView(View view);
public native void handleEvent(View view);

@Override
public void onClick(View view) {
    handleEvent(view);
}

@Override
public void onValueChange(@NonNull Slider slider, float value, boolean fromUser) {
    handleEvent(slider);
}

} ```