zorldo

Goofing around with Ebiten
git clone git://bsandro.tech/zorldo
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impl_android.go (3727B)

      1 // Copyright 2016 Hajime Hoshi
      2 //
      3 // Licensed under the Apache License, Version 2.0 (the "License");
      4 // you may not use this file except in compliance with the License.
      5 // You may obtain a copy of the License at
      6 //
      7 //     http://www.apache.org/licenses/LICENSE-2.0
      8 //
      9 // Unless required by applicable law or agreed to in writing, software
     10 // distributed under the License is distributed on an "AS IS" BASIS,
     11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     12 // See the License for the specific language governing permissions and
     13 // limitations under the License.
     14 
     15 package devicescale
     16 
     17 /*
     18 
     19 #include <jni.h>
     20 #include <stdlib.h>
     21 
     22 // Basically same as:
     23 //
     24 //     WindowService windowService = context.getSystemService(Context.WINDOW_SERVICE);
     25 //     Display display = windowManager.getDefaultDisplay();
     26 //     DisplayMetrics displayMetrics = new DisplayMetrics();
     27 //     display.getRealMetrics(displayMetrics);
     28 //     this.deviceScale = displayMetrics.density;
     29 //
     30 static float deviceScale(uintptr_t java_vm, uintptr_t jni_env, uintptr_t ctx) {
     31   JavaVM* vm = (JavaVM*)java_vm;
     32   JNIEnv* env = (JNIEnv*)jni_env;
     33   jobject context = (jobject)ctx;
     34 
     35   const char* kWindowService = "window";
     36 
     37   const jclass android_content_Context =
     38       (*env)->FindClass(env, "android/content/Context");
     39   const jclass android_view_WindowManager =
     40       (*env)->FindClass(env, "android/view/WindowManager");
     41   const jclass android_view_Display =
     42       (*env)->FindClass(env, "android/view/Display");
     43   const jclass android_util_DisplayMetrics =
     44       (*env)->FindClass(env, "android/util/DisplayMetrics");
     45 
     46   const jobject android_context_Context_WINDOW_SERVICE =
     47       (*env)->GetStaticObjectField(
     48           env, android_content_Context,
     49           (*env)->GetStaticFieldID(env, android_content_Context, "WINDOW_SERVICE", "Ljava/lang/String;"));
     50 
     51   const jobject windowManager =
     52       (*env)->CallObjectMethod(
     53           env, context,
     54           (*env)->GetMethodID(env, android_content_Context, "getSystemService", "(Ljava/lang/String;)Ljava/lang/Object;"),
     55           android_context_Context_WINDOW_SERVICE);
     56   const jobject display =
     57       (*env)->CallObjectMethod(
     58           env, windowManager,
     59           (*env)->GetMethodID(env, android_view_WindowManager, "getDefaultDisplay", "()Landroid/view/Display;"));
     60   const jobject displayMetrics =
     61       (*env)->NewObject(
     62           env, android_util_DisplayMetrics,
     63           (*env)->GetMethodID(env, android_util_DisplayMetrics, "<init>", "()V"));
     64   (*env)->CallVoidMethod(
     65       env, display,
     66       (*env)->GetMethodID(env, android_view_Display, "getRealMetrics", "(Landroid/util/DisplayMetrics;)V"),
     67       displayMetrics);
     68   const float density =
     69       (*env)->GetFloatField(
     70           env, displayMetrics,
     71           (*env)->GetFieldID(env, android_util_DisplayMetrics, "density", "F"));
     72 
     73   (*env)->DeleteLocalRef(env, android_content_Context);
     74   (*env)->DeleteLocalRef(env, android_view_WindowManager);
     75   (*env)->DeleteLocalRef(env, android_view_Display);
     76   (*env)->DeleteLocalRef(env, android_util_DisplayMetrics);
     77 
     78   (*env)->DeleteLocalRef(env, android_context_Context_WINDOW_SERVICE);
     79   (*env)->DeleteLocalRef(env, windowManager);
     80   (*env)->DeleteLocalRef(env, display);
     81   (*env)->DeleteLocalRef(env, displayMetrics);
     82 
     83   return density;
     84 }
     85 
     86 */
     87 import "C"
     88 
     89 import (
     90 	"fmt"
     91 
     92 	"golang.org/x/mobile/app"
     93 )
     94 
     95 func impl(x, y int) float64 {
     96 	s := 0.0
     97 	if err := app.RunOnJVM(func(vm, env, ctx uintptr) error {
     98 		// TODO: This might be crash when this is called from init(). How can we detect this?
     99 		s = float64(C.deviceScale(C.uintptr_t(vm), C.uintptr_t(env), C.uintptr_t(ctx)))
    100 		return nil
    101 	}); err != nil {
    102 		panic(fmt.Sprintf("devicescale: error %v", err))
    103 	}
    104 	return s
    105 }