1 /*
   2  * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 #include "systemScale.h"
  26 #include <d2d1.h>
  27 #pragma comment(lib, "d2d1")
  28 #include <jdk_util.h>
  29 #ifndef MDT_EFFECTIVE_DPI
  30 #define MDT_EFFECTIVE_DPI 0
  31 #endif
  32 
  33 void GetScreenDpi(HMONITOR hmon, float *dpiX, float *dpiY)
  34 {
  35     unsigned x = 0;
  36     unsigned y = 0;
  37 
  38     // for debug purposes
  39     static float scale = -2.0f;
  40     if (scale == -2) {
  41         scale = -1;
  42         char *uiScale = getenv("J2D_UISCALE");
  43         if (uiScale != NULL) {
  44             scale = (float)strtod(uiScale, NULL);
  45             if (errno == ERANGE || scale <= 0) {
  46                 scale = -1;
  47             }
  48         }
  49     }
  50 
  51     if (scale > 0) {
  52         *dpiX = *dpiY = scale;
  53         return;
  54     }
  55 
  56     typedef HRESULT(WINAPI GetDpiForMonitorFunc)(HMONITOR, int, UINT*, UINT*);
  57     static HMODULE hLibSHCoreDll = NULL;
  58     static GetDpiForMonitorFunc *lpGetDpiForMonitor = NULL;
  59 
  60     if (hLibSHCoreDll == NULL) {
  61         hLibSHCoreDll = JDK_LoadSystemLibrary("shcore.dll");
  62         if (hLibSHCoreDll != NULL) {
  63             lpGetDpiForMonitor = (GetDpiForMonitorFunc*)GetProcAddress(
  64                 hLibSHCoreDll, "GetDpiForMonitor");
  65         }
  66     }
  67 
  68     if (lpGetDpiForMonitor != NULL) {
  69         HRESULT hResult = lpGetDpiForMonitor(hmon,
  70                                              MDT_EFFECTIVE_DPI, &x, &y);
  71         if (hResult == S_OK) {
  72             *dpiX = static_cast<float>(x);
  73             *dpiY = static_cast<float>(y);
  74         }
  75     } else {
  76         ID2D1Factory* m_pDirect2dFactory;
  77         HRESULT res = D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED,
  78                                         &m_pDirect2dFactory);
  79         if (res == S_OK) {
  80             m_pDirect2dFactory->GetDesktopDpi(dpiX, dpiY);
  81             m_pDirect2dFactory->Release();
  82         }
  83     }
  84     return;
  85 }
  86 
  87 HMONITOR WINAPI getPrimaryMonitor()
  88 {
  89     const POINT point = { 0, 0 };
  90     return MonitorFromPoint(point, MONITOR_DEFAULTTOPRIMARY);
  91 }