// 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.

// +build !js

package ui

// #cgo LDFLAGS: -lgdi32
//
// #include <windows.h>
//
// static char* getDPI(int* dpi) {
//   HDC dc = GetWindowDC(0);
//   *dpi = GetDeviceCaps(dc, LOGPIXELSX);
//   if (!ReleaseDC(0, dc)) {
//     return "ReleaseDC failed";
//   }
//   return "";
// }
import "C"

func deviceScale() float64 {
	dpi := C.int(0)
	if errmsg := C.GoString(C.getDPI(&dpi)); errmsg != "" {
		panic(errmsg)
	}
	return float64(dpi) / 96
}

func glfwScale() float64 {
	return deviceScale()
}

// 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.

// +build !js

package ui

// #cgo LDFLAGS: -lgdi32
//
// #include <windows.h>
//
// static int getDPI() {
//   HDC dc = GetWindowDC(0);
//   int dpi = GetDeviceCaps(dc, LOGPIXELSX);
//   ReleaseDC(0, dc);
//   return dpi;
// }
import "C"

func deviceScale() float64 {
	dpi := int(C.getDPI())
	return float64(dpi) / 96
}

func glfwScale() float64 {
	return deviceScale()
}

--- 
+++ 
@@ -20,16 +20,21 @@
 //
 // #include <windows.h>
 //
-// static int getDPI() {
+// static char* getDPI(int* dpi) {
 //   HDC dc = GetWindowDC(0);
-//   int dpi = GetDeviceCaps(dc, LOGPIXELSX);
-//   ReleaseDC(0, dc);
-//   return dpi;
+//   *dpi = GetDeviceCaps(dc, LOGPIXELSX);
+//   if (!ReleaseDC(0, dc)) {
+//     return "ReleaseDC failed";
+//   }
+//   return "";
 // }
 import "C"
 
 func deviceScale() float64 {
-	dpi := int(C.getDPI())
+	dpi := C.int(0)
+	if errmsg := C.GoString(C.getDPI(&dpi)); errmsg != "" {
+		panic(errmsg)
+	}
 	return float64(dpi) / 96
 }
 
ui: Check the return value of ReleaseDC()
