From b9a131bae8b0858d111984a13410b8b5312656d3 Mon Sep 17 00:00:00 2001
From: Francisco Madgaleno <franciscojma86@gmail.com>
Date: Tue, 1 Oct 2019 15:38:30 -0700
Subject: [PATCH 01/10] Support system dpi awareness for older versions of
 Windows

---
 shell/platform/windows/win32_dpi_helper.cc | 28 ++++++++++++++++++++--
 shell/platform/windows/win32_dpi_helper.h  | 15 ++++++++++++
 shell/platform/windows/win32_window.cc     | 25 ++++++++++++-------
 shell/platform/windows/win32_window.h      |  2 +-
 4 files changed, 59 insertions(+), 11 deletions(-)

diff --git a/shell/platform/windows/win32_dpi_helper.cc b/shell/platform/windows/win32_dpi_helper.cc
index c31044ce2c767..1b23430ca9ec2 100644
--- a/shell/platform/windows/win32_dpi_helper.cc
+++ b/shell/platform/windows/win32_dpi_helper.cc
@@ -1,5 +1,7 @@
 #include "flutter/shell/platform/windows/win32_dpi_helper.h"
 
+#include <iostream>
+
 namespace flutter {
 
 namespace {
@@ -18,7 +20,6 @@ Win32DpiHelper::Win32DpiHelper() {
   if (user32_module_ == nullptr) {
     return;
   }
-
   if (!AssignProcAddress(user32_module_, "EnableNonClientDpiScaling",
                          enable_non_client_dpi_scaling_)) {
     return;
@@ -33,7 +34,6 @@ Win32DpiHelper::Win32DpiHelper() {
                          set_process_dpi_awareness_context_)) {
     return;
   }
-
   permonitorv2_supported_ = true;
 }
 
@@ -43,6 +43,22 @@ Win32DpiHelper::~Win32DpiHelper() {
   }
 }
 
+// SetAwareness
+// Check the available api. Start with v2, then fall back.
+void Win32DpiHelper::SetDpiAwerenessAllVersions() {
+  if (permonitorv2_supported_) {
+    SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2);
+  } else {
+    std::cerr << "Per Monitor V2 DPI awareness is not supported on this "
+                 "version of Windows. Setting System DPI awareness\n";
+    AssignProcAddress(user32_module_, "GetDpiForSystem", get_dpi_for_system_);
+    AssignProcAddress(user32_module_, "SetProcessDpiAware",
+                      set_process_dpi_aware_);
+
+    SetProcessDPIAware();
+  }
+}
+
 bool Win32DpiHelper::IsPerMonitorV2Available() {
   return permonitorv2_supported_;
 }
@@ -61,6 +77,10 @@ UINT Win32DpiHelper::GetDpiForWindow(HWND hwnd) {
   return get_dpi_for_window_(hwnd);
 }
 
+UINT Win32DpiHelper::GetDpiForSystem() {
+  return get_dpi_for_system_();
+}
+
 BOOL Win32DpiHelper::SetProcessDpiAwarenessContext(
     DPI_AWARENESS_CONTEXT context) {
   if (!permonitorv2_supported_) {
@@ -69,4 +89,8 @@ BOOL Win32DpiHelper::SetProcessDpiAwarenessContext(
   return set_process_dpi_awareness_context_(context);
 }
 
+BOOL Win32DpiHelper::SetProcessDpiAware() {
+  return set_process_dpi_aware_();
+}
+
 }  // namespace flutter
diff --git a/shell/platform/windows/win32_dpi_helper.h b/shell/platform/windows/win32_dpi_helper.h
index ddf51184bf956..8ba635cee0859 100644
--- a/shell/platform/windows/win32_dpi_helper.h
+++ b/shell/platform/windows/win32_dpi_helper.h
@@ -28,17 +28,32 @@ class Win32DpiHelper {
   // Wrapper for OS functionality to return the DPI for |HWND|
   UINT GetDpiForWindow(HWND);
 
+  // Wrapper for OS functionality to return the DPI for the System. Only used if
+  // Per Monitor V2 is not supported by the current Windows version.
+  UINT GetDpiForSystem();
+
   // Sets the current process to a specified DPI awareness context.
   BOOL SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT);
 
+  // Sets the current process to System-level DPI awareness.
+  BOOL SetProcessDpiAware();
+
+  // Sets the DPI awareness for the application. For versions >= Windows 1703,
+  // use Per Monitor V2. For any older versions, use System.
+  void SetDpiAwerenessAllVersions();
+
  private:
   using EnableNonClientDpiScaling_ = BOOL __stdcall(HWND);
   using GetDpiForWindow_ = UINT __stdcall(HWND);
   using SetProcessDpiAwarenessContext_ = BOOL __stdcall(DPI_AWARENESS_CONTEXT);
+  using SetProcessDpiAware_ = BOOL __stdcall();
+  using GetDpiForSystem_ = UINT __stdcall();
 
   EnableNonClientDpiScaling_* enable_non_client_dpi_scaling_ = nullptr;
   GetDpiForWindow_* get_dpi_for_window_ = nullptr;
   SetProcessDpiAwarenessContext_* set_process_dpi_awareness_context_ = nullptr;
+  SetProcessDpiAware_* set_process_dpi_aware_ = nullptr;
+  GetDpiForSystem_* get_dpi_for_system_ = nullptr;
 
   HMODULE user32_module_ = nullptr;
   bool permonitorv2_supported_ = false;
diff --git a/shell/platform/windows/win32_window.cc b/shell/platform/windows/win32_window.cc
index 43690efec2753..3462bd5067b09 100644
--- a/shell/platform/windows/win32_window.cc
+++ b/shell/platform/windows/win32_window.cc
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "flutter/shell/platform/windows/win32_window.h"
+#include <iostream>
 
 namespace flutter {
 
@@ -26,7 +27,11 @@ void Win32Window::InitializeChild(const char* title,
   Destroy();
   std::wstring converted_title = NarrowToWide(title);
 
-  WNDCLASS window_class = ResgisterWindowClass(converted_title);
+  // Set DPI awareness for all Windows versions. This call has to be made before
+  // the HWND is created.
+  dpi_helper_->SetDpiAwerenessAllVersions();
+
+  WNDCLASS window_class = RegisterWindowClass(converted_title);
 
   auto* result = CreateWindowEx(
       0, window_class.lpszClassName, converted_title.c_str(),
@@ -54,7 +59,7 @@ std::wstring Win32Window::NarrowToWide(const char* source) {
   return wideTitle;
 }
 
-WNDCLASS Win32Window::ResgisterWindowClass(std::wstring& title) {
+WNDCLASS Win32Window::RegisterWindowClass(std::wstring& title) {
   window_class_name_ = title;
 
   WNDCLASS window_class{};
@@ -83,13 +88,17 @@ LRESULT CALLBACK Win32Window::WndProc(HWND const window,
 
     auto that = static_cast<Win32Window*>(cs->lpCreateParams);
 
-    // Since the application is running in Per-monitor V2 mode, turn on
-    // automatic titlebar scaling
-    BOOL result = that->dpi_helper_->EnableNonClientDpiScaling(window);
-    if (result != TRUE) {
-      OutputDebugString(L"Failed to enable non-client area autoscaling");
+    if (that->dpi_helper_->IsPerMonitorV2Available()) {
+      // Since the application is running in Per-monitor V2 mode, turn on
+      // automatic titlebar scaling
+      BOOL result = that->dpi_helper_->EnableNonClientDpiScaling(window);
+      if (result != TRUE) {
+        OutputDebugString(L"Failed to enable non-client area autoscaling");
+      }
+      that->current_dpi_ = that->dpi_helper_->GetDpiForWindow(window);
+    } else {
+      that->current_dpi_ = that->dpi_helper_->GetDpiForSystem();
     }
-    that->current_dpi_ = that->dpi_helper_->GetDpiForWindow(window);
     that->window_handle_ = window;
   } else if (Win32Window* that = GetThisFromHandle(window)) {
     return that->MessageHandler(window, message, wparam, lparam);
diff --git a/shell/platform/windows/win32_window.h b/shell/platform/windows/win32_window.h
index e670a52519308..63a00c355dea6 100644
--- a/shell/platform/windows/win32_window.h
+++ b/shell/platform/windows/win32_window.h
@@ -57,7 +57,7 @@ class Win32Window {
 
   // Registers a window class with default style attributes, cursor and
   // icon.
-  WNDCLASS ResgisterWindowClass(std::wstring& title);
+  WNDCLASS RegisterWindowClass(std::wstring& title);
 
   // OS callback called by message pump.  Handles the WM_NCCREATE message which
   // is passed when the non-client area is being created and enables automatic

From f04b0b9848a8927b302ef3591bf4e4f863c0a4c5 Mon Sep 17 00:00:00 2001
From: Francisco Madgaleno <franciscojma86@gmail.com>
Date: Tue, 1 Oct 2019 18:42:24 -0700
Subject: [PATCH 02/10] Fix documentation

---
 shell/platform/windows/win32_dpi_helper.cc | 2 --
 shell/platform/windows/win32_window.cc     | 1 -
 2 files changed, 3 deletions(-)

diff --git a/shell/platform/windows/win32_dpi_helper.cc b/shell/platform/windows/win32_dpi_helper.cc
index 1b23430ca9ec2..eaa6be5765e01 100644
--- a/shell/platform/windows/win32_dpi_helper.cc
+++ b/shell/platform/windows/win32_dpi_helper.cc
@@ -43,8 +43,6 @@ Win32DpiHelper::~Win32DpiHelper() {
   }
 }
 
-// SetAwareness
-// Check the available api. Start with v2, then fall back.
 void Win32DpiHelper::SetDpiAwerenessAllVersions() {
   if (permonitorv2_supported_) {
     SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2);
diff --git a/shell/platform/windows/win32_window.cc b/shell/platform/windows/win32_window.cc
index 3462bd5067b09..1cda8cba0fb6b 100644
--- a/shell/platform/windows/win32_window.cc
+++ b/shell/platform/windows/win32_window.cc
@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 #include "flutter/shell/platform/windows/win32_window.h"
-#include <iostream>
 
 namespace flutter {
 

From 4f5eae92cc7a5e582f96d116db5587837b950e41 Mon Sep 17 00:00:00 2001
From: Francisco Madgaleno <franciscojma86@gmail.com>
Date: Tue, 1 Oct 2019 18:46:26 -0700
Subject: [PATCH 03/10] Fix documentation

---
 shell/platform/windows/win32_dpi_helper.h |  3 +++
 shell/platform/windows/win32_window.cc    | 12 ++----------
 2 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/shell/platform/windows/win32_dpi_helper.h b/shell/platform/windows/win32_dpi_helper.h
index 8ba635cee0859..196affab9f2e2 100644
--- a/shell/platform/windows/win32_dpi_helper.h
+++ b/shell/platform/windows/win32_dpi_helper.h
@@ -40,6 +40,9 @@ class Win32DpiHelper {
 
   // Sets the DPI awareness for the application. For versions >= Windows 1703,
   // use Per Monitor V2. For any older versions, use System.
+  //
+  // This call is overriden if DPI awareness is stated in the application
+  // manifest.
   void SetDpiAwerenessAllVersions();
 
  private:
diff --git a/shell/platform/windows/win32_window.cc b/shell/platform/windows/win32_window.cc
index 1cda8cba0fb6b..702827da2915b 100644
--- a/shell/platform/windows/win32_window.cc
+++ b/shell/platform/windows/win32_window.cc
@@ -6,16 +6,8 @@
 
 namespace flutter {
 
-Win32Window::Win32Window() {
-  // Assume Windows 10 1703 or greater for DPI handling.  When running on a
-  // older release of Windows where this context doesn't exist, DPI calls will
-  // fail and Flutter rendering will be impacted until this is fixed.
-  // To handle downlevel correctly, dpi_helper must use the most recent DPI
-  // context available should be used: Windows 1703: Per-Monitor V2, 8.1:
-  // Per-Monitor V1, Windows 7: System See
-  // https://docs.microsoft.com/en-us/windows/win32/hidpi/high-dpi-desktop-application-development-on-windows
-  // for more information.
-}
+Win32Window::Win32Window() {}
+
 Win32Window::~Win32Window() {
   Destroy();
 }

From 040295d23c46aa727087da3833364cf6409445db Mon Sep 17 00:00:00 2001
From: Francisco Madgaleno <franciscojma86@gmail.com>
Date: Wed, 2 Oct 2019 09:46:16 -0700
Subject: [PATCH 04/10] Address comments

---
 shell/platform/windows/win32_dpi_helper.cc | 34 +++++-----------------
 shell/platform/windows/win32_dpi_helper.h  | 11 +++----
 shell/platform/windows/win32_window.cc     | 11 +++----
 3 files changed, 18 insertions(+), 38 deletions(-)

diff --git a/shell/platform/windows/win32_dpi_helper.cc b/shell/platform/windows/win32_dpi_helper.cc
index eaa6be5765e01..5843def87e43f 100644
--- a/shell/platform/windows/win32_dpi_helper.cc
+++ b/shell/platform/windows/win32_dpi_helper.cc
@@ -1,7 +1,5 @@
 #include "flutter/shell/platform/windows/win32_dpi_helper.h"
 
-#include <iostream>
-
 namespace flutter {
 
 namespace {
@@ -43,17 +41,17 @@ Win32DpiHelper::~Win32DpiHelper() {
   }
 }
 
-void Win32DpiHelper::SetDpiAwerenessAllVersions() {
+BOOL Win32DpiHelper::SetDpiAwareness() {
   if (permonitorv2_supported_) {
-    SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2);
+    return set_process_dpi_awareness_context_(
+        DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2);
+
   } else {
-    std::cerr << "Per Monitor V2 DPI awareness is not supported on this "
-                 "version of Windows. Setting System DPI awareness\n";
     AssignProcAddress(user32_module_, "GetDpiForSystem", get_dpi_for_system_);
     AssignProcAddress(user32_module_, "SetProcessDpiAware",
                       set_process_dpi_aware_);
 
-    SetProcessDPIAware();
+    return set_process_dpi_aware_();
   }
 }
 
@@ -68,27 +66,11 @@ BOOL Win32DpiHelper::EnableNonClientDpiScaling(HWND hwnd) {
   return enable_non_client_dpi_scaling_(hwnd);
 }
 
-UINT Win32DpiHelper::GetDpiForWindow(HWND hwnd) {
-  if (!permonitorv2_supported_) {
-    return false;
+UINT Win32DpiHelper::GetDpi(HWND hwnd) {
+  if (permonitorv2_supported_) {
+    return get_dpi_for_window_(hwnd);
   }
-  return get_dpi_for_window_(hwnd);
-}
-
-UINT Win32DpiHelper::GetDpiForSystem() {
   return get_dpi_for_system_();
 }
 
-BOOL Win32DpiHelper::SetProcessDpiAwarenessContext(
-    DPI_AWARENESS_CONTEXT context) {
-  if (!permonitorv2_supported_) {
-    return false;
-  }
-  return set_process_dpi_awareness_context_(context);
-}
-
-BOOL Win32DpiHelper::SetProcessDpiAware() {
-  return set_process_dpi_aware_();
-}
-
 }  // namespace flutter
diff --git a/shell/platform/windows/win32_dpi_helper.h b/shell/platform/windows/win32_dpi_helper.h
index 196affab9f2e2..3d55f72f6c9f2 100644
--- a/shell/platform/windows/win32_dpi_helper.h
+++ b/shell/platform/windows/win32_dpi_helper.h
@@ -25,12 +25,9 @@ class Win32DpiHelper {
   // Wrapper for OS functionality to turn on automatic window non-client scaling
   BOOL EnableNonClientDpiScaling(HWND);
 
-  // Wrapper for OS functionality to return the DPI for |HWND|
-  UINT GetDpiForWindow(HWND);
-
-  // Wrapper for OS functionality to return the DPI for the System. Only used if
-  // Per Monitor V2 is not supported by the current Windows version.
-  UINT GetDpiForSystem();
+  // Wrapper for OS functionality to return the DPI for |HWND| if Per Monitor V2
+  // awareness has been set. Otherwise, returns the DPI for the System.
+  UINT GetDpi(HWND);
 
   // Sets the current process to a specified DPI awareness context.
   BOOL SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT);
@@ -43,7 +40,7 @@ class Win32DpiHelper {
   //
   // This call is overriden if DPI awareness is stated in the application
   // manifest.
-  void SetDpiAwerenessAllVersions();
+  BOOL SetDpiAwareness();
 
  private:
   using EnableNonClientDpiScaling_ = BOOL __stdcall(HWND);
diff --git a/shell/platform/windows/win32_window.cc b/shell/platform/windows/win32_window.cc
index 702827da2915b..2b1c2bdc12141 100644
--- a/shell/platform/windows/win32_window.cc
+++ b/shell/platform/windows/win32_window.cc
@@ -20,7 +20,9 @@ void Win32Window::InitializeChild(const char* title,
 
   // Set DPI awareness for all Windows versions. This call has to be made before
   // the HWND is created.
-  dpi_helper_->SetDpiAwerenessAllVersions();
+  if (!dpi_helper_->SetDpiAwareness()) {
+    OutputDebugString(L"Failed to set DPI awareness");
+  }
 
   WNDCLASS window_class = RegisterWindowClass(converted_title);
 
@@ -86,10 +88,9 @@ LRESULT CALLBACK Win32Window::WndProc(HWND const window,
       if (result != TRUE) {
         OutputDebugString(L"Failed to enable non-client area autoscaling");
       }
-      that->current_dpi_ = that->dpi_helper_->GetDpiForWindow(window);
-    } else {
-      that->current_dpi_ = that->dpi_helper_->GetDpiForSystem();
     }
+    that->current_dpi_ = that->dpi_helper_->GetDpi(window);
+
     that->window_handle_ = window;
   } else if (Win32Window* that = GetThisFromHandle(window)) {
     return that->MessageHandler(window, message, wparam, lparam);
@@ -282,7 +283,7 @@ Win32Window::HandleDpiChange(HWND hwnd,
     // The DPI is only passed for DPI change messages on top level windows,
     // hence call function to get DPI if needed.
     if (uDpi == 0) {
-      uDpi = dpi_helper_->GetDpiForWindow(hwnd);
+      uDpi = dpi_helper_->GetDpi(hwnd);
     }
     current_dpi_ = uDpi;
     window->OnDpiScale(uDpi);

From c6f3aae469a2909b9d5b1c2a3ea565d0a028c788 Mon Sep 17 00:00:00 2001
From: Francisco Madgaleno <franciscojma86@gmail.com>
Date: Wed, 2 Oct 2019 09:46:57 -0700
Subject: [PATCH 05/10] Remove unused call

---
 shell/platform/windows/win32_dpi_helper.h | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/shell/platform/windows/win32_dpi_helper.h b/shell/platform/windows/win32_dpi_helper.h
index 3d55f72f6c9f2..6f06d8024d79e 100644
--- a/shell/platform/windows/win32_dpi_helper.h
+++ b/shell/platform/windows/win32_dpi_helper.h
@@ -29,9 +29,6 @@ class Win32DpiHelper {
   // awareness has been set. Otherwise, returns the DPI for the System.
   UINT GetDpi(HWND);
 
-  // Sets the current process to a specified DPI awareness context.
-  BOOL SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT);
-
   // Sets the current process to System-level DPI awareness.
   BOOL SetProcessDpiAware();
 

From b2f68e370c4543cd98ff1ab6330bab709d663965 Mon Sep 17 00:00:00 2001
From: Francisco Madgaleno <franciscojma86@gmail.com>
Date: Wed, 2 Oct 2019 09:51:04 -0700
Subject: [PATCH 06/10] Another one

---
 shell/platform/windows/win32_dpi_helper.h | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/shell/platform/windows/win32_dpi_helper.h b/shell/platform/windows/win32_dpi_helper.h
index 6f06d8024d79e..013f215e540ae 100644
--- a/shell/platform/windows/win32_dpi_helper.h
+++ b/shell/platform/windows/win32_dpi_helper.h
@@ -29,9 +29,6 @@ class Win32DpiHelper {
   // awareness has been set. Otherwise, returns the DPI for the System.
   UINT GetDpi(HWND);
 
-  // Sets the current process to System-level DPI awareness.
-  BOOL SetProcessDpiAware();
-
   // Sets the DPI awareness for the application. For versions >= Windows 1703,
   // use Per Monitor V2. For any older versions, use System.
   //

From a9eb31cd0111218dd8800fe6752d133356c2186f Mon Sep 17 00:00:00 2001
From: Francisco Madgaleno <franciscojma86@gmail.com>
Date: Thu, 23 Jan 2020 14:58:50 -0800
Subject: [PATCH 07/10] Changed to get

---
 shell/platform/windows/win32_dpi_helper.cc | 66 ++++++++++------------
 shell/platform/windows/win32_dpi_helper.h  | 38 +++++--------
 shell/platform/windows/win32_window.cc     | 17 +-----
 3 files changed, 43 insertions(+), 78 deletions(-)

diff --git a/shell/platform/windows/win32_dpi_helper.cc b/shell/platform/windows/win32_dpi_helper.cc
index 5843def87e43f..f9d9c37487fc0 100644
--- a/shell/platform/windows/win32_dpi_helper.cc
+++ b/shell/platform/windows/win32_dpi_helper.cc
@@ -13,64 +13,56 @@ bool AssignProcAddress(HMODULE comBaseModule, const char* name, T*& outProc) {
 }  // namespace
 
 Win32DpiHelper::Win32DpiHelper() {
-  // TODO ensure that this helper works correctly on downlevel builds.
   user32_module_ = LoadLibraryA("User32.dll");
   if (user32_module_ == nullptr) {
     return;
   }
-  if (!AssignProcAddress(user32_module_, "EnableNonClientDpiScaling",
-                         enable_non_client_dpi_scaling_)) {
+  shlib_module_ = LoadLibraryA("Shcore.dll");
+  if (shlib_module_ == nullptr) {
     return;
   }
 
-  if (!AssignProcAddress(user32_module_, "GetDpiForWindow",
-                         get_dpi_for_window_)) {
-    return;
+  if (AssignProcAddress(user32_module_, "GetDpiForWindow",
+                        get_dpi_for_window_)) {
+    dpi_for_window_supported_ = true;
   }
 
-  if (!AssignProcAddress(user32_module_, "SetProcessDpiAwarenessContext",
-                         set_process_dpi_awareness_context_)) {
-    return;
+  if (AssignProcAddress(shlib_module_, "GetDpiForMonitor",
+                        get_dpi_for_monitor_) &&
+      AssignProcAddress(user32_module_, "MonitorFromWindow",
+                        monitor_from_window_)) {
+    dpi_for_monitor_supported_ = true;
   }
-  permonitorv2_supported_ = true;
 }
 
 Win32DpiHelper::~Win32DpiHelper() {
   if (user32_module_ != nullptr) {
     FreeLibrary(user32_module_);
   }
-}
-
-BOOL Win32DpiHelper::SetDpiAwareness() {
-  if (permonitorv2_supported_) {
-    return set_process_dpi_awareness_context_(
-        DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2);
-
-  } else {
-    AssignProcAddress(user32_module_, "GetDpiForSystem", get_dpi_for_system_);
-    AssignProcAddress(user32_module_, "SetProcessDpiAware",
-                      set_process_dpi_aware_);
-
-    return set_process_dpi_aware_();
-  }
-}
-
-bool Win32DpiHelper::IsPerMonitorV2Available() {
-  return permonitorv2_supported_;
-}
-
-BOOL Win32DpiHelper::EnableNonClientDpiScaling(HWND hwnd) {
-  if (!permonitorv2_supported_) {
-    return false;
+  if (shlib_module_ != nullptr) {
+    FreeLibrary(shlib_module_);
   }
-  return enable_non_client_dpi_scaling_(hwnd);
 }
 
 UINT Win32DpiHelper::GetDpi(HWND hwnd) {
-  if (permonitorv2_supported_) {
+  // GetDpiForWindow returns the DPI for any awareness mode. If not available, fallback to a
+  // per monitor, system, or default DPI.
+  if (dpi_for_window_supported_) {
     return get_dpi_for_window_(hwnd);
+  } else if (dpi_for_monitor_supported_) {
+    HMONITOR monitor = monitor_from_window_(hwnd, MONITOR_DEFAULTTONEAREST);
+    UINT dpi_x = 0, dpi_y = 0;
+    HRESULT result =
+        get_dpi_for_monitor_(monitor, MDT_EFFECTIVE_DPI, &dpi_x, &dpi_y);
+    if (result == S_OK) {
+      return dpi_x;
+    }
+  } else {
+    HDC hdc = GetDC(hwnd);
+    UINT dpi = GetDeviceCaps(hdc, LOGPIXELSX);
+    ReleaseDC(hwnd, hdc);
+    return dpi;
   }
-  return get_dpi_for_system_();
+  return default_dpi_;
 }
-
 }  // namespace flutter
diff --git a/shell/platform/windows/win32_dpi_helper.h b/shell/platform/windows/win32_dpi_helper.h
index 013f215e540ae..7e67d8c1a47ba 100644
--- a/shell/platform/windows/win32_dpi_helper.h
+++ b/shell/platform/windows/win32_dpi_helper.h
@@ -18,39 +18,27 @@ class Win32DpiHelper {
 
   ~Win32DpiHelper();
 
-  // Check if Windows Per Monitor V2 DPI scaling functionality is available on
-  // current system.
-  bool IsPerMonitorV2Available();
-
-  // Wrapper for OS functionality to turn on automatic window non-client scaling
-  BOOL EnableNonClientDpiScaling(HWND);
-
-  // Wrapper for OS functionality to return the DPI for |HWND| if Per Monitor V2
-  // awareness has been set. Otherwise, returns the DPI for the System.
+  // Returns the current DPI. Supports all DPI awareness modes, and is backward
+  // compatible down to Windows Vista.
   UINT GetDpi(HWND);
 
-  // Sets the DPI awareness for the application. For versions >= Windows 1703,
-  // use Per Monitor V2. For any older versions, use System.
-  //
-  // This call is overriden if DPI awareness is stated in the application
-  // manifest.
-  BOOL SetDpiAwareness();
-
  private:
-  using EnableNonClientDpiScaling_ = BOOL __stdcall(HWND);
   using GetDpiForWindow_ = UINT __stdcall(HWND);
-  using SetProcessDpiAwarenessContext_ = BOOL __stdcall(DPI_AWARENESS_CONTEXT);
-  using SetProcessDpiAware_ = BOOL __stdcall();
-  using GetDpiForSystem_ = UINT __stdcall();
+  using GetDpiForMonitor_ = HRESULT __stdcall(HMONITOR hmonitor,
+                                              MONITOR_DPI_TYPE dpiType,
+                                              UINT* dpiX,
+                                              UINT* dpiY);
+  using MonitorFromWindow_ = HMONITOR __stdcall(HWND hwnd, DWORD dwFlags);
 
-  EnableNonClientDpiScaling_* enable_non_client_dpi_scaling_ = nullptr;
   GetDpiForWindow_* get_dpi_for_window_ = nullptr;
-  SetProcessDpiAwarenessContext_* set_process_dpi_awareness_context_ = nullptr;
-  SetProcessDpiAware_* set_process_dpi_aware_ = nullptr;
-  GetDpiForSystem_* get_dpi_for_system_ = nullptr;
+  GetDpiForMonitor_* get_dpi_for_monitor_ = nullptr;
+  MonitorFromWindow_* monitor_from_window_ = nullptr;
 
   HMODULE user32_module_ = nullptr;
-  bool permonitorv2_supported_ = false;
+  HMODULE shlib_module_ = nullptr;
+  bool dpi_for_window_supported_ = false;
+  bool dpi_for_monitor_supported_ = false;
+  UINT default_dpi_ = 96;
 };
 
 }  // namespace flutter
diff --git a/shell/platform/windows/win32_window.cc b/shell/platform/windows/win32_window.cc
index 2b1c2bdc12141..3a63b1eb6ae52 100644
--- a/shell/platform/windows/win32_window.cc
+++ b/shell/platform/windows/win32_window.cc
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "flutter/shell/platform/windows/win32_window.h"
+#include <iostream>
 
 namespace flutter {
 
@@ -18,12 +19,6 @@ void Win32Window::InitializeChild(const char* title,
   Destroy();
   std::wstring converted_title = NarrowToWide(title);
 
-  // Set DPI awareness for all Windows versions. This call has to be made before
-  // the HWND is created.
-  if (!dpi_helper_->SetDpiAwareness()) {
-    OutputDebugString(L"Failed to set DPI awareness");
-  }
-
   WNDCLASS window_class = RegisterWindowClass(converted_title);
 
   auto* result = CreateWindowEx(
@@ -80,17 +75,7 @@ LRESULT CALLBACK Win32Window::WndProc(HWND const window,
                      reinterpret_cast<LONG_PTR>(cs->lpCreateParams));
 
     auto that = static_cast<Win32Window*>(cs->lpCreateParams);
-
-    if (that->dpi_helper_->IsPerMonitorV2Available()) {
-      // Since the application is running in Per-monitor V2 mode, turn on
-      // automatic titlebar scaling
-      BOOL result = that->dpi_helper_->EnableNonClientDpiScaling(window);
-      if (result != TRUE) {
-        OutputDebugString(L"Failed to enable non-client area autoscaling");
-      }
-    }
     that->current_dpi_ = that->dpi_helper_->GetDpi(window);
-
     that->window_handle_ = window;
   } else if (Win32Window* that = GetThisFromHandle(window)) {
     return that->MessageHandler(window, message, wparam, lparam);

From 408d22d7846679e613ebb14b27e28ba14bb35d67 Mon Sep 17 00:00:00 2001
From: Francisco Madgaleno <franciscojma86@gmail.com>
Date: Thu, 23 Jan 2020 15:09:10 -0800
Subject: [PATCH 08/10] Format

---
 shell/platform/windows/win32_dpi_helper.cc | 4 ++--
 shell/platform/windows/win32_window.cc     | 1 -
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/shell/platform/windows/win32_dpi_helper.cc b/shell/platform/windows/win32_dpi_helper.cc
index f9d9c37487fc0..dd74d249be86a 100644
--- a/shell/platform/windows/win32_dpi_helper.cc
+++ b/shell/platform/windows/win32_dpi_helper.cc
@@ -45,8 +45,8 @@ Win32DpiHelper::~Win32DpiHelper() {
 }
 
 UINT Win32DpiHelper::GetDpi(HWND hwnd) {
-  // GetDpiForWindow returns the DPI for any awareness mode. If not available, fallback to a
-  // per monitor, system, or default DPI.
+  // GetDpiForWindow returns the DPI for any awareness mode. If not available,
+  // fallback to a per monitor, system, or default DPI.
   if (dpi_for_window_supported_) {
     return get_dpi_for_window_(hwnd);
   } else if (dpi_for_monitor_supported_) {
diff --git a/shell/platform/windows/win32_window.cc b/shell/platform/windows/win32_window.cc
index 3a63b1eb6ae52..e499bfbd129f8 100644
--- a/shell/platform/windows/win32_window.cc
+++ b/shell/platform/windows/win32_window.cc
@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 #include "flutter/shell/platform/windows/win32_window.h"
-#include <iostream>
 
 namespace flutter {
 

From 61bc8105dfeeef3c159428b1ac25f2a42b2cd9dd Mon Sep 17 00:00:00 2001
From: Francisco Madgaleno <franciscojma86@gmail.com>
Date: Thu, 23 Jan 2020 15:11:18 -0800
Subject: [PATCH 09/10] Documentation

---
 shell/platform/windows/win32_dpi_helper.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/shell/platform/windows/win32_dpi_helper.h b/shell/platform/windows/win32_dpi_helper.h
index 7e67d8c1a47ba..2bbf69aa0ad4a 100644
--- a/shell/platform/windows/win32_dpi_helper.h
+++ b/shell/platform/windows/win32_dpi_helper.h
@@ -10,16 +10,16 @@
 
 namespace flutter {
 
-// A helper class for abstracting various Windows DPI related functions across
-// Windows OS versions.
+/// A helper class for abstracting various Windows DPI related functions across
+/// Windows OS versions.
 class Win32DpiHelper {
  public:
   Win32DpiHelper();
 
   ~Win32DpiHelper();
 
-  // Returns the current DPI. Supports all DPI awareness modes, and is backward
-  // compatible down to Windows Vista.
+  /// Returns the current DPI. Supports all DPI awareness modes, and is backward
+  /// compatible down to Windows Vista.
   UINT GetDpi(HWND);
 
  private:

From 1bb1a02c840bd31f5b4c2c8fea6d7b9289e98fc3 Mon Sep 17 00:00:00 2001
From: Francisco Madgaleno <franciscojma86@gmail.com>
Date: Thu, 23 Jan 2020 16:43:15 -0800
Subject: [PATCH 10/10] Address review

---
 shell/platform/windows/win32_dpi_helper.cc | 31 ++++++++++++----------
 shell/platform/windows/win32_dpi_helper.h  |  1 -
 2 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/shell/platform/windows/win32_dpi_helper.cc b/shell/platform/windows/win32_dpi_helper.cc
index dd74d249be86a..40a79e72c31d9 100644
--- a/shell/platform/windows/win32_dpi_helper.cc
+++ b/shell/platform/windows/win32_dpi_helper.cc
@@ -4,6 +4,8 @@ namespace flutter {
 
 namespace {
 
+constexpr UINT kDefaultDpi = 96;
+
 template <typename T>
 bool AssignProcAddress(HMODULE comBaseModule, const char* name, T*& outProc) {
   outProc = reinterpret_cast<T*>(GetProcAddress(comBaseModule, name));
@@ -17,14 +19,16 @@ Win32DpiHelper::Win32DpiHelper() {
   if (user32_module_ == nullptr) {
     return;
   }
-  shlib_module_ = LoadLibraryA("Shcore.dll");
-  if (shlib_module_ == nullptr) {
-    return;
-  }
 
   if (AssignProcAddress(user32_module_, "GetDpiForWindow",
                         get_dpi_for_window_)) {
     dpi_for_window_supported_ = true;
+    return;
+  }
+
+  shlib_module_ = LoadLibraryA("Shcore.dll");
+  if (shlib_module_ == nullptr) {
+    return;
   }
 
   if (AssignProcAddress(shlib_module_, "GetDpiForMonitor",
@@ -49,20 +53,19 @@ UINT Win32DpiHelper::GetDpi(HWND hwnd) {
   // fallback to a per monitor, system, or default DPI.
   if (dpi_for_window_supported_) {
     return get_dpi_for_window_(hwnd);
-  } else if (dpi_for_monitor_supported_) {
+  }
+
+  if (dpi_for_monitor_supported_) {
     HMONITOR monitor = monitor_from_window_(hwnd, MONITOR_DEFAULTTONEAREST);
     UINT dpi_x = 0, dpi_y = 0;
     HRESULT result =
         get_dpi_for_monitor_(monitor, MDT_EFFECTIVE_DPI, &dpi_x, &dpi_y);
-    if (result == S_OK) {
-      return dpi_x;
-    }
-  } else {
-    HDC hdc = GetDC(hwnd);
-    UINT dpi = GetDeviceCaps(hdc, LOGPIXELSX);
-    ReleaseDC(hwnd, hdc);
-    return dpi;
+    return SUCCEEDED(result) ? dpi_x : kDefaultDpi;
   }
-  return default_dpi_;
+
+  HDC hdc = GetDC(hwnd);
+  UINT dpi = GetDeviceCaps(hdc, LOGPIXELSX);
+  ReleaseDC(hwnd, hdc);
+  return dpi;
 }
 }  // namespace flutter
diff --git a/shell/platform/windows/win32_dpi_helper.h b/shell/platform/windows/win32_dpi_helper.h
index 2bbf69aa0ad4a..6ded84836713f 100644
--- a/shell/platform/windows/win32_dpi_helper.h
+++ b/shell/platform/windows/win32_dpi_helper.h
@@ -38,7 +38,6 @@ class Win32DpiHelper {
   HMODULE shlib_module_ = nullptr;
   bool dpi_for_window_supported_ = false;
   bool dpi_for_monitor_supported_ = false;
-  UINT default_dpi_ = 96;
 };
 
 }  // namespace flutter