adjust ios dpr

com.unity.uiwidgets/Runtime/engine2/DisplayMetrics.cs

+using System.Runtime.InteropServices;
 using UnityEngine;
 
 namespace Unity.UIWidgets.engine2 {
                 
 #if UNITY_ANDROID
                 _devicePixelRatioByDefault = AndroidDevicePixelRatio();
+#endif
+
+#if UNITY_IOS
+                _devicePixelRatioByDefault = DisplayMetrics.IOSDeviceScaleFactor();
 #endif
 
                 if (_devicePixelRatioByDefault <= 0) {
                 }
             }
         }
+#endif
+
+#if UNITY_IOS
+        [DllImport("__Internal")]
+        static extern float IOSDeviceScaleFactor();
+
+//         [DllImport(“__Internal”)]
+//         static extern viewMetrics IOSGetViewportPadding();
 #endif
 
     }

engine/Build.bee.cs

                 "src/shell/platform/unity/darwin/ios/cocoa_task_runner.h",
                 "src/shell/platform/unity/darwin/ios/unity_surface_manager.mm",
                 "src/shell/platform/unity/darwin/ios/unity_surface_manager.h",
+                "src/shell/platform/unity/darwin/ios/DeviceScreen.mm",
+                "src/shell/platform/unity/darwin/ios/UIWidgetsDevice.mm",
+                "src/shell/platform/unity/darwin/ios/UIWidgetsDevice.h",
         };
 
         np.Sources.Add(c => IsWindows(c), winSources);

engine/src/shell/platform/unity/darwin/ios/DeviceScreen.mm

+#import <UIKit/UIKit.h>
+#import "UIWidgetsDevice.h"
+extern "C"
+{
+    float IOSDeviceScaleFactor(){
+        float scale = [[UIScreen mainScreen] scale] * 1.0;
+        if([UIWidgetsDevice NeedScreenDownSample]){
+            scale *= 0.8696;
+        }
+        return scale;
+    }
+}

engine/src/shell/platform/unity/darwin/ios/UIWidgetsDevice.h

+//
+//  UIWidgetsDevice.h
+//  Unity-iPhone
+//
+//  Created by Xingwei Zhu on 2019/6/24.
+//
+
+#ifndef UIWidgetsDevice_h
+#define UIWidgetsDevice_h
+
+#import <UIKit/UIKit.h>
+
+@interface UIWidgetsDevice : NSObject
+
++(NSString *) deviceName;
+
++(BOOL) NeedScreenDownSample;
+
+@end
+
+#endif /* UIWidgetsDevice_h */

engine/src/shell/platform/unity/darwin/ios/UIWidgetsDevice.mm

+//
+//  UIWidgetsDevice.m
+//  Unity-iPhone
+//
+//  Created by Xingwei Zhu on 2019/6/24.
+//
+#include "UIWidgetsDevice.h"
+#import <sys/utsname.h>
+#import <UIKit/UIKit.h>
+
+static NSString* _deviceName = nil;
+
+@implementation UIWidgetsDevice
+
++ (NSString *) deviceName
+{
+    if (_deviceName != nil) {
+        return _deviceName;
+    }
+    
+    struct utsname systemInfo;
+    uname(&systemInfo);
+    NSString* code = [NSString stringWithCString:systemInfo.machine encoding:NSUTF8StringEncoding];
+    
+    NSDictionary* deviceNamesByCode = @{
+                                        @"i386"      : @"Simulator",
+                                        @"x86_64"    : @"Simulator",
+                                        @"iPod1,1"   : @"iPod Touch",        // (Original)
+                                        @"iPod2,1"   : @"iPod Touch",        // (Second Generation)
+                                        @"iPod3,1"   : @"iPod Touch",        // (Third Generation)
+                                        @"iPod4,1"   : @"iPod Touch",        // (Fourth Generation)
+                                        @"iPod7,1"   : @"iPod Touch",        // (6th Generation)
+                                        @"iPhone1,1" : @"iPhone",            // (Original)
+                                        @"iPhone1,2" : @"iPhone",            // (3G)
+                                        @"iPhone2,1" : @"iPhone",            // (3GS)
+                                        @"iPad1,1"   : @"iPad",              // (Original)
+                                        @"iPad2,1"   : @"iPad 2",            //
+                                        @"iPad3,1"   : @"iPad",              // (3rd Generation)
+                                        @"iPhone3,1" : @"iPhone 4",          // (GSM)
+                                        @"iPhone3,3" : @"iPhone 4",          // (CDMA/Verizon/Sprint)
+                                        @"iPhone4,1" : @"iPhone 4S",         //
+                                        @"iPhone5,1" : @"iPhone 5",          // (model A1428, AT&T/Canada)
+                                        @"iPhone5,2" : @"iPhone 5",          // (model A1429, everything else)
+                                        @"iPad3,4"   : @"iPad",              // (4th Generation)
+                                        @"iPad2,5"   : @"iPad Mini",         // (Original)
+                                        @"iPhone5,3" : @"iPhone 5C",         // (model A1456, A1532 | GSM)
+                                        @"iPhone5,4" : @"iPhone 5C",         // (model A1507, A1516, A1526 (China), A1529 | Global)
+                                        @"iPhone6,1" : @"iPhone 5S",         // (model A1433, A1533 | GSM)
+                                        @"iPhone6,2" : @"iPhone 5S",         // (model A1457, A1518, A1528 (China), A1530 | Global)
+                                        @"iPhone7,1" : @"iPhone 6 Plus",     //
+                                        @"iPhone7,2" : @"iPhone 6",          //
+                                        @"iPhone8,1" : @"iPhone 6S",         //
+                                        @"iPhone8,2" : @"iPhone 6S Plus",    //
+                                        @"iPhone8,4" : @"iPhone SE",         //
+                                        @"iPhone9,1" : @"iPhone 7",          //
+                                        @"iPhone9,3" : @"iPhone 7",          //
+                                        @"iPhone9,2" : @"iPhone 7 Plus",     //
+                                        @"iPhone9,4" : @"iPhone 7 Plus",     //
+                                        @"iPhone10,1": @"iPhone 8",          // CDMA
+                                        @"iPhone10,4": @"iPhone 8",          // GSM
+                                        @"iPhone10,2": @"iPhone 8 Plus",     // CDMA
+                                        @"iPhone10,5": @"iPhone 8 Plus",     // GSM
+                                        @"iPhone10,3": @"iPhone X",          // CDMA
+                                        @"iPhone10,6": @"iPhone X",          // GSM
+                                        @"iPhone11,2": @"iPhone XS",         //
+                                        @"iPhone11,4": @"iPhone XS Max",     //
+                                        @"iPhone11,6": @"iPhone XS Max",     // China
+                                        @"iPhone11,8": @"iPhone XR",         //
+                                        
+                                        @"iPad4,1"   : @"iPad Air",          // 5th Generation iPad (iPad Air) - Wifi
+                                        @"iPad4,2"   : @"iPad Air",          // 5th Generation iPad (iPad Air) - Cellular
+                                        @"iPad4,4"   : @"iPad Mini",         // (2nd Generation iPad Mini - Wifi)
+                                        @"iPad4,5"   : @"iPad Mini",         // (2nd Generation iPad Mini - Cellular)
+                                        @"iPad4,7"   : @"iPad Mini",         // (3rd Generation iPad Mini - Wifi (model A1599))
+                                        @"iPad6,7"   : @"iPad Pro (12.9\")", // iPad Pro 12.9 inches - (model A1584)
+                                        @"iPad6,8"   : @"iPad Pro (12.9\")", // iPad Pro 12.9 inches - (model A1652)
+                                        @"iPad6,3"   : @"iPad Pro (9.7\")",  // iPad Pro 9.7 inches - (model A1673)
+                                        @"iPad6,4"   : @"iPad Pro (9.7\")"
+                                        };
+    _deviceName = [deviceNamesByCode objectForKey:code];
+    
+    if (!_deviceName) {
+        if ([code rangeOfString:@"iPod"].location != NSNotFound) {
+            _deviceName = @"iPod Touch";
+        }
+        else if([code rangeOfString:@"iPad"].location != NSNotFound) {
+            _deviceName = @"iPad";
+        }
+        else if([code rangeOfString:@"iPhone"].location != NSNotFound){
+            _deviceName = @"iPhone";
+        }
+        else {
+            _deviceName = @"Unknown";
+        }
+    }
+    
+    if ([_deviceName isEqualToString:@"Simulator"]) {
+        if([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
+            switch ((int)[[UIScreen mainScreen] nativeBounds].size.height) {
+                    //iPhone 5 or 5S or 5C
+                case 1136:
+                    _deviceName = @"iPhone 5 Simulator";
+                    break;
+                    //iPhone 6 or 6S or 7 or 8
+                case 1334:
+                    _deviceName = @"iPhone 6 Simulator";
+                    break;
+                    //iPhone 6+ or 6S+ or 7+ or 8+
+                case 1920:
+                    _deviceName = @"iPhone 6 Plus Simulator";
+                    break;
+                    //iPhone 6+ or 6S+ or 7+ or 8+
+                case 2208:
+                    _deviceName = @"iPhone 6 Plus Simulator";
+                    break;
+                    //iPhone X or XS
+                case 2436:
+                    _deviceName = @"iPhone X Simulator";
+                    break;
+                    //iPhone XS Max
+                case 2688:
+                    _deviceName = @"iPhone XS Max Simulator";
+                    break;
+                    //iPhone XR
+                case 1792:
+                    _deviceName = @"iPhone XR Simulator";
+                    break;
+                default:
+                    _deviceName = @"Unknown Simulator";
+                    break;
+            }
+        }
+    }
+    
+    return _deviceName;
+}
+
++ (BOOL) NeedScreenDownSample
+{
+    return  [[UIWidgetsDevice deviceName] isEqualToString:@"iPhone 6 Plus"] ||
+            [[UIWidgetsDevice deviceName] isEqualToString:@"iPhone 6S Plus"] ||
+            [[UIWidgetsDevice deviceName] isEqualToString:@"iPhone 7 Plus"] ||
+            [[UIWidgetsDevice deviceName] isEqualToString:@"iPhone 8 Plus"];
+}
+
+@end