internal/ui: move impls for device scale to internal/ui for mobiles

internal/devicescale/devicescale.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build !js
+//go:build !android && !ios && !js
 
 package devicescale
 

internal/devicescale/impl_android.go

@@ -1,105 +0,0 @@
-// Copyright 2016 Hajime Hoshi
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package devicescale
-
-/*
-
-#include <jni.h>
-#include <stdlib.h>
-
-// Basically same as:
-//
-//     WindowService windowService = context.getSystemService(Context.WINDOW_SERVICE);
-//     Display display = windowManager.getDefaultDisplay();
-//     DisplayMetrics displayMetrics = new DisplayMetrics();
-//     display.getRealMetrics(displayMetrics);
-//     this.deviceScale = displayMetrics.density;
-//
-static float deviceScale(uintptr_t java_vm, uintptr_t jni_env, uintptr_t ctx) {
-  JavaVM* vm = (JavaVM*)java_vm;
-  JNIEnv* env = (JNIEnv*)jni_env;
-  jobject context = (jobject)ctx;
-
-  const char* kWindowService = "window";
-
-  const jclass android_content_Context =
-      (*env)->FindClass(env, "android/content/Context");
-  const jclass android_view_WindowManager =
-      (*env)->FindClass(env, "android/view/WindowManager");
-  const jclass android_view_Display =
-      (*env)->FindClass(env, "android/view/Display");
-  const jclass android_util_DisplayMetrics =
-      (*env)->FindClass(env, "android/util/DisplayMetrics");
-
-  const jobject android_context_Context_WINDOW_SERVICE =
-      (*env)->GetStaticObjectField(
-          env, android_content_Context,
-          (*env)->GetStaticFieldID(env, android_content_Context, "WINDOW_SERVICE", "Ljava/lang/String;"));
-
-  const jobject windowManager =
-      (*env)->CallObjectMethod(
-          env, context,
-          (*env)->GetMethodID(env, android_content_Context, "getSystemService", "(Ljava/lang/String;)Ljava/lang/Object;"),
-          android_context_Context_WINDOW_SERVICE);
-  const jobject display =
-      (*env)->CallObjectMethod(
-          env, windowManager,
-          (*env)->GetMethodID(env, android_view_WindowManager, "getDefaultDisplay", "()Landroid/view/Display;"));
-  const jobject displayMetrics =
-      (*env)->NewObject(
-          env, android_util_DisplayMetrics,
-          (*env)->GetMethodID(env, android_util_DisplayMetrics, "<init>", "()V"));
-  (*env)->CallVoidMethod(
-      env, display,
-      (*env)->GetMethodID(env, android_view_Display, "getRealMetrics", "(Landroid/util/DisplayMetrics;)V"),
-      displayMetrics);
-  const float density =
-      (*env)->GetFloatField(
-          env, displayMetrics,
-          (*env)->GetFieldID(env, android_util_DisplayMetrics, "density", "F"));
-
-  (*env)->DeleteLocalRef(env, android_content_Context);
-  (*env)->DeleteLocalRef(env, android_view_WindowManager);
-  (*env)->DeleteLocalRef(env, android_view_Display);
-  (*env)->DeleteLocalRef(env, android_util_DisplayMetrics);
-
-  (*env)->DeleteLocalRef(env, android_context_Context_WINDOW_SERVICE);
-  (*env)->DeleteLocalRef(env, windowManager);
-  (*env)->DeleteLocalRef(env, display);
-  (*env)->DeleteLocalRef(env, displayMetrics);
-
-  return density;
-}
-
-*/
-import "C"
-
-import (
-	"fmt"
-
-	"golang.org/x/mobile/app"
-)
-
-func impl(x, y int) float64 {
-	s := 0.0
-	if err := app.RunOnJVM(func(vm, env, ctx uintptr) error {
-		// TODO: This might be crash when this is called from init(). How can we detect this?
-		s = float64(C.deviceScale(C.uintptr_t(vm), C.uintptr_t(env), C.uintptr_t(ctx)))
-		return nil
-	}); err != nil {
-		panic(fmt.Sprintf("devicescale: error %v", err))
-	}
-	return s
-}

internal/devicescale/impl_ios.go

@@ -1,29 +0,0 @@
-// Copyright 2016 Hajime Hoshi
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package devicescale
-
-// #cgo CFLAGS: -x objective-c
-// #cgo LDFLAGS: -framework Foundation -framework UIKit
-//
-// #import <UIKit/UIKit.h>
-//
-// static double devicePixelRatio() {
-//   return [[UIScreen mainScreen] nativeScale];
-// }
-import "C"
-
-func impl(x, y int) float64 {
-	return float64(C.devicePixelRatio())
-}

internal/ui/ui_android.go

@@ -14,7 +14,80 @@
 
 package ui
 
+/*
+#include <jni.h>
+#include <stdlib.h>
+
+// Basically same as:
+//
+//     WindowService windowService = context.getSystemService(Context.WINDOW_SERVICE);
+//     Display display = windowManager.getDefaultDisplay();
+//     DisplayMetrics displayMetrics = new DisplayMetrics();
+//     display.getRealMetrics(displayMetrics);
+//     this.deviceScale = displayMetrics.density;
+//
+static float deviceScale(uintptr_t java_vm, uintptr_t jni_env, uintptr_t ctx) {
+  JavaVM* vm = (JavaVM*)java_vm;
+  JNIEnv* env = (JNIEnv*)jni_env;
+  jobject context = (jobject)ctx;
+
+  const char* kWindowService = "window";
+
+  const jclass android_content_Context =
+      (*env)->FindClass(env, "android/content/Context");
+  const jclass android_view_WindowManager =
+      (*env)->FindClass(env, "android/view/WindowManager");
+  const jclass android_view_Display =
+      (*env)->FindClass(env, "android/view/Display");
+  const jclass android_util_DisplayMetrics =
+      (*env)->FindClass(env, "android/util/DisplayMetrics");
+
+  const jobject android_context_Context_WINDOW_SERVICE =
+      (*env)->GetStaticObjectField(
+          env, android_content_Context,
+          (*env)->GetStaticFieldID(env, android_content_Context, "WINDOW_SERVICE", "Ljava/lang/String;"));
+
+  const jobject windowManager =
+      (*env)->CallObjectMethod(
+          env, context,
+          (*env)->GetMethodID(env, android_content_Context, "getSystemService", "(Ljava/lang/String;)Ljava/lang/Object;"),
+          android_context_Context_WINDOW_SERVICE);
+  const jobject display =
+      (*env)->CallObjectMethod(
+          env, windowManager,
+          (*env)->GetMethodID(env, android_view_WindowManager, "getDefaultDisplay", "()Landroid/view/Display;"));
+  const jobject displayMetrics =
+      (*env)->NewObject(
+          env, android_util_DisplayMetrics,
+          (*env)->GetMethodID(env, android_util_DisplayMetrics, "<init>", "()V"));
+  (*env)->CallVoidMethod(
+      env, display,
+      (*env)->GetMethodID(env, android_view_Display, "getRealMetrics", "(Landroid/util/DisplayMetrics;)V"),
+      displayMetrics);
+  const float density =
+      (*env)->GetFloatField(
+          env, displayMetrics,
+          (*env)->GetFieldID(env, android_util_DisplayMetrics, "density", "F"));
+
+  (*env)->DeleteLocalRef(env, android_content_Context);
+  (*env)->DeleteLocalRef(env, android_view_WindowManager);
+  (*env)->DeleteLocalRef(env, android_view_Display);
+  (*env)->DeleteLocalRef(env, android_util_DisplayMetrics);
+
+  (*env)->DeleteLocalRef(env, android_context_Context_WINDOW_SERVICE);
+  (*env)->DeleteLocalRef(env, windowManager);
+  (*env)->DeleteLocalRef(env, display);
+  (*env)->DeleteLocalRef(env, displayMetrics);
+
+  return density;
+}
+*/
+import "C"
+
 import (
+	"fmt"
+
+	"golang.org/x/mobile/app"
 	"golang.org/x/mobile/gl"
 
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver"
@@ -41,3 +114,15 @@ func (*graphicsDriverCreatorImpl) newDirectX() (graphicsdriver.Graphics, error)
 func (*graphicsDriverCreatorImpl) newMetal() (graphicsdriver.Graphics, error) {
 	return nil, nil
 }
+
+func deviceScaleFactorImpl() float64 {
+	var s float64
+	if err := app.RunOnJVM(func(vm, env, ctx uintptr) error {
+		// TODO: This might be crash when this is called from init(). How can we detect this?
+		s = float64(C.deviceScale(C.uintptr_t(vm), C.uintptr_t(env), C.uintptr_t(ctx)))
+		return nil
+	}); err != nil {
+		panic(fmt.Sprintf("devicescale: error %v", err))
+	}
+	return s
+}

internal/ui/ui_ios.go

@@ -14,6 +14,16 @@
 
 package ui
 
+// #cgo CFLAGS: -x objective-c
+// #cgo LDFLAGS: -framework Foundation -framework UIKit
+//
+// #import <UIKit/UIKit.h>
+//
+// static double devicePixelRatio() {
+//   return [[UIScreen mainScreen] nativeScale];
+// }
+import "C"
+
 import (
 	"fmt"
 
@@ -86,3 +96,8 @@ func (u *userInterfaceImpl) isGL() (bool, error) {
 
 	return u.graphicsDriver.IsGL(), nil
 }
+
+func deviceScaleFactorImpl() float64 {
+	// TODO: Can this be called from non-main threads?
+	return float64(C.devicePixelRatio())
+}

internal/ui/ui_mobile.go

@@ -33,7 +33,6 @@ import (
 	"golang.org/x/mobile/event/touch"
 	"golang.org/x/mobile/gl"
 
-	"github.com/hajimehoshi/ebiten/v2/internal/devicescale"
 	"github.com/hajimehoshi/ebiten/v2/internal/gamepad"
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicscommand"
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver"
@@ -102,6 +101,9 @@ type userInterfaceImpl struct {
 	outsideWidth  float64
 	outsideHeight float64
 
+	deviceScaleFactorOnce sync.Once
+	deviceScaleFactor     float64
+
 	foreground int32
 	errCh      chan error
 
@@ -124,10 +126,6 @@ type userInterfaceImpl struct {
 	m sync.RWMutex
 }
 
-func deviceScale() float64 {
-	return devicescale.GetAt(0, 0)
-}
-
 // appMain is the main routine for gomobile-build mode.
 func (u *userInterfaceImpl) appMain(a app.App) {
 	var glctx gl.Context
@@ -185,7 +183,7 @@ func (u *userInterfaceImpl) appMain(a app.App) {
 			}
 			switch e.Type {
 			case touch.TypeBegin, touch.TypeMove:
-				s := deviceScale()
+				s := u.DeviceScaleFactor()
 				touches[e.Sequence] = TouchForInput{
 					ID: TouchID(e.Sequence),
 					X:  float64(e.X) / s,
@@ -317,7 +315,7 @@ func (u *userInterfaceImpl) outsideSize() (float64, float64) {
 		outsideHeight = u.outsideHeight
 	} else {
 		// gomobile build
-		d := deviceScale()
+		d := u.DeviceScaleFactor()
 		outsideWidth = float64(u.gbuildWidthPx) / d
 		outsideHeight = float64(u.gbuildHeightPx) / d
 	}
@@ -333,7 +331,7 @@ func (u *userInterfaceImpl) update() error {
 	}()
 
 	w, h := u.outsideSize()
-	if err := u.context.updateFrame(u.graphicsDriver, w, h, deviceScale(), u, nil); err != nil {
+	if err := u.context.updateFrame(u.graphicsDriver, w, h, u.DeviceScaleFactor(), u, nil); err != nil {
 		return err
 	}
 	return nil
@@ -417,7 +415,11 @@ func (u *userInterfaceImpl) updateExplicitRenderingModeIfNeeded() {
 }
 
 func (u *userInterfaceImpl) DeviceScaleFactor() float64 {
-	return deviceScale()
+	// Assume that the device scale factor never changes on mobiles.
+	u.deviceScaleFactorOnce.Do(func() {
+		u.deviceScaleFactor = deviceScaleFactorImpl()
+	})
+	return u.deviceScaleFactor
 }
 
 func (u *userInterfaceImpl) readInputState(inputState *InputState) {