Flutter 控制屏幕旋轉的實現

發布時間：2020-10-21 23:56:06 來源：腳本之家閱讀：836 作者：一天清晨欄目：開發技術

最近需要做個平板的項目，然后需要直接橫屏，有2種實現方式。

1, 隨著屏幕旋轉，布局自動調整。做橫豎屏適配

2，強制屏幕橫屏，不隨著屏幕去調整

第一種方式這里就不做說明了。代碼做適配就可以。下面說一下第二種實現方式

Flutter 自帶方式

flutter 為我們提供了方法來控制系統的橫豎屏顯示

 SystemChrome.setPreferredOrientations([
   DeviceOrientation.landscapeLeft,
   DeviceOrientation.landscapeRight,
   DeviceOrientation.portraitUp,
   DeviceOrientation.portraitDown
  ]).then((_) {
  });

包含的方向類型。！！！！但是但是但是這個方法只適用于android在iOS上沒有效果，上網查資料有大神封裝的 flutter插件orientation ,flutter插件auto_orientation 在iOS上都起不到效果，所以打算自己寫一個原生文件與flutter進行通訊，實現屏幕旋轉。也是筆者在查詢資料之后做的一個整合和解釋說明

iOS端實現屏幕旋轉

創建iOS原生文件

創建iOS原生文件來實現交互，首先要創建個原生文件。命名為FlutterIOSDevicePlugin。創建文件

創建一個命名為FlutterIOSDevicePlugin.h 和命名為FlutterIOSDevicePlugin.m文件，說明一下： FlutterIOSDevicePlugin.h文件選擇圖片里面的header File模塊創建即可。

創建之后，一起看一下FlutterIOSDevicePlugin.h里面的代碼

#ifndef FlutterIOSDevicePlugin_h
#define FlutterIOSDevicePlugin_h

#import <Flutter/Flutter.h>

@interface FlutterIOSDevicePlugin : NSObject<FlutterPlugin>
+ (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar flutterViewController:(FlutterViewController*) controller;
- (instancetype)newInstance:(NSObject<FlutterPluginRegistrar>*)registrar flutterViewController:(FlutterViewController*) controller;
@end
#endif /* FlutterIOSDevicePlugin_h */

這個不需要過多說明了看一下FlutterIOSDevicePlugin.m的代碼

#import <Foundation/Foundation.h>
#import "FlutterIOSDevicePlugin.h"

@interface FlutterIOSDevicePlugin () {
  NSObject<FlutterPluginRegistrar> *_registrar;
  FlutterViewController *_controller;
}
@end

static NSString* const CHANNEL_NAME = @"flutter_ios_device";
static NSString* const METHOD_CHANGE_ORIENTATION = @"change_screen_orientation";
static NSString* const ORIENTATION_PORTRAIT_UP = @"portraitUp";
static NSString* const ORIENTATION_PORTRAIT_DOWN = @"portraitDown";
static NSString* const ORIENTATION_LANDSCAPE_LEFT = @"landscapeLeft";
static NSString* const ORIENTATION_LANDSCAPE_RIGHT = @"landscapeRight";

@implementation FlutterIOSDevicePlugin
+ (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar {
  FlutterMethodChannel* channel = [FlutterMethodChannel
                   methodChannelWithName:CHANNEL_NAME
                   binaryMessenger:[registrar messenger]];
  FlutterIOSDevicePlugin* instance = [[FlutterIOSDevicePlugin alloc] newInstance:registrar flutterViewController:nil];
  [registrar addMethodCallDelegate:instance channel:channel];
}

+ (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar flutterViewController:(FlutterViewController*) controller {
  FlutterMethodChannel* channel = [FlutterMethodChannel
                   methodChannelWithName:CHANNEL_NAME
                   binaryMessenger:[registrar messenger]];
  FlutterIOSDevicePlugin* instance = [[FlutterIOSDevicePlugin alloc] newInstance:registrar flutterViewController:controller];
  [registrar addMethodCallDelegate:instance channel:channel];
}

- (instancetype)newInstance:(NSObject<FlutterPluginRegistrar>*)registrar flutterViewController:(FlutterViewController*) controller{
  _registrar = registrar;
  _controller = controller;
  return self;
}

- (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
  if ([METHOD_CHANGE_ORIENTATION isEqualToString:call.method]) {
    NSArray *arguments = call.arguments;
    NSString *orientation = arguments[0];
    NSNumber *index = [NSNumber numberWithInt: [call.arguments[0] intValue]];
    NSInteger iOSOrientation;
     if ([orientation isEqualToString:ORIENTATION_LANDSCAPE_LEFT]){
           iOSOrientation = UIDeviceOrientationLandscapeLeft;
         }else if([orientation isEqualToString:ORIENTATION_LANDSCAPE_RIGHT]){
           iOSOrientation = UIDeviceOrientationLandscapeRight;
         }else if ([orientation isEqualToString:ORIENTATION_PORTRAIT_DOWN]){
           iOSOrientation = UIDeviceOrientationPortraitUpsideDown;
         }else{
           iOSOrientation = UIDeviceOrientationPortrait;
         }

    [[UIDevice currentDevice] setValue:@(iOSOrientation) forKey:@"orientation"];
//    [[NSNotificationCenter defaultCenter] postNotificationName:@"FlutterIOSDevicePlugin" object:nil userInfo:@{@"orientationMask": index}];
//    [UIViewController attemptRotationToDeviceOrientation];

    result(nil);
  } else {
    result(FlutterMethodNotImplemented);
  }
}
@end

以上是全部的代碼，其中嘗試了用通知的方式去做屏幕旋轉，后來發現其實沒有那么麻煩，直接采用的是

[[UIDevice currentDevice] setValue:@(iOSOrientation) forKey:@"orientation"];

方式做的。其中遇到的問題：

問題1:iphone手機上可以正常旋轉，ipad上不行

這個問題主要原因是info。plist文件里面的iphone和ipad不一致，且勾選Requires full screen 即可

回到正軌哈

注冊原生插件文件

iOS 工程種有個GeneratedPluginRegistrant.m文件，直接注冊就可以了。如果你項目引入了其他第三方插件，也是統一在這個地方注冊的

#import "GeneratedPluginRegistrant.h"

#if __has_include(<auto_orientation/AutoOrientationPlugin.h>)
#import <auto_orientation/AutoOrientationPlugin.h>
#else
@import auto_orientation;
#endif

#if __has_include(<orientation/OrientationPlugin.h>)
#import <orientation/OrientationPlugin.h>
#else
@import orientation;
#endif
#import "FlutterIOSDevicePlugin.h"

@implementation GeneratedPluginRegistrant

+ (void)registerWithRegistry:(NSObject<FlutterPluginRegistry>*)registry {
 [AutoOrientationPlugin registerWithRegistrar:[registry registrarForPlugin:@"AutoOrientationPlugin"]];
 [OrientationPlugin registerWithRegistrar:[registry registrarForPlugin:@"OrientationPlugin"]];
//  [registry registrarForPlugin:@"FlutterIOSDevicePlugin"];
  

  [FlutterIOSDevicePlugin registerWithRegistrar: [registry registrarForPlugin:@"FlutterIOSDevicePlugin"]];
}

@end

代碼中的這個片段是自己寫的插件注冊的方法，其他的AutoOrientationPlugin，OrientationPlugin是引用第三方插件自動生成的代碼。

[FlutterIOSDevicePlugin registerWithRegistrar: [registry registrarForPlugin:@"FlutterIOSDevicePlugin"]];

AppDelegate文件中的設置

import UIKit
import Flutter



@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
 var orientationMask: UIInterfaceOrientationMask = .all;
  
 override func application(
  _ application: UIApplication,
  didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
 ) -> Bool {
  NotificationCenter.default.addObserver(self, selector: #selector(changeLandscape(center:)), name:NSNotification.Name(rawValue: "FlutterIOSDevicePlugin"), object: nil)
  GeneratedPluginRegistrant.register(with: self);
  return super.application(application, didFinishLaunchingWithOptions: launchOptions)
 }
  override func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {
    return orientationMask;
  }
  
  @objc func changeLandscape(center: Notification){
    let index: NSNumber = (center.userInfo?["orientationMask"] ?? 5) as! NSNumber
    var mask : UIInterfaceOrientationMask = .all
    switch index {
    case 0:
      mask = .portrait
      break
    case 1:
      mask = .landscapeLeft
      break
    case 2:
      mask = .landscapeRight
      break
    case 3:
      mask = .portraitUpsideDown
      break
    case 4:
      mask = .landscape
      break
    case 5:
      mask = .all
      break
    case 6:
      mask = .allButUpsideDown
      break
    
    default:
      mask = .all
      break
    }
    orientationMask = mask;
    _ = application(UIApplication.shared, supportedInterfaceOrientationsFor: UIApplication.shared.keyWindow)
  }
}

其中changeLandscape方法是控制監聽的事件的方法，目前沒什么用。主要代碼是這一段，這個是在發出屏幕旋轉的時候回調的方法，這里面設置的是全部的方向都可以。

  override func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {
    return orientationMask;
  }

問題2:程序不走該方法

具體原因是因為info.plist文件問題。參考上面設置就沒問題

flutter 原生代碼使用

這個地方是針對于iOS平臺去做的區別。

MethodChannel _channel = const MethodChannel('flutter_ios_device');

@override
 void initState() {
  SystemChrome.setPreferredOrientations([
   DeviceOrientation.landscapeLeft,
   DeviceOrientation.landscapeRight,
   DeviceOrientation.portraitUp,
   DeviceOrientation.portraitDown
  ]).then((_) {
   if (Platform.isIOS) {
    this.changeScreenOrientation(DeviceOrientation.landscapeLeft);
   }
  });
  super.initState();
 }
 
Future<void> changeScreenOrientation(DeviceOrientation orientation) {
  String o;
  switch (orientation) {
   case DeviceOrientation.portraitUp:
    o = 'portraitUp';
    break;
   case DeviceOrientation.portraitDown:
    o = 'portraitDown';
    break;
   case DeviceOrientation.landscapeLeft:
    o = 'landscapeLeft';
    break;
   case DeviceOrientation.landscapeRight:
    o = 'landscapeRight';
    break;
  }
  return _channel.invokeMethod('change_screen_orientation', [o]);
 }

代碼不用過多說明了，有不了解的可以留言

問題3: 啟動程序自動旋轉

SystemChrome.setPreferredOrientations需要設置全部內容。不然會默認旋轉。有點小坑，

以上基本上可以實現屏幕旋轉的問題，如果有小伙伴還是不行，可以試一下用iOS原生通知的方式去完成。這個我做的是平板的項目，暫時沒有問題，更多相關Flutter 控制屏幕旋轉內容請搜索億速云以前的文章或繼續瀏覽下面的相關文章希望大家以后多多支持億速云！

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