Fix issues with High DPI support on Windows (#358).

Both main process and subprocesses are now set to be DPI aware
when cef.DpiAware.EnableHighDpiSupport function is called.

- Update docs/MigrationGuide.md document.
- Update examples/wxpython.py
- Add DpiAware.EnableHighDpiSupport function.
- Deprecate DpiAware.SetProcessDpiAware function.
- Deprecate ApplicationSettings.auto_zooming "system_dpi" value

Author: cztomczak

.gitignore

@@ -7,3 +7,5 @@ __pycache__/
 cefclient
 webcache/
 examples/screenshot.png
+examples/pyinstaller/build/
+examples/pyinstaller/dist/

README.md

@@ -476,6 +476,7 @@ Additional information for v31.2 release:
 * [DownloadHandler](api/DownloadHandler.md#downloadhandler)
 * [DpiAware (class)](api/DpiAware.md#dpiaware-class)
   * [CalculateWindowSize](api/DpiAware.md#calculatewindowsize)
+  * [EnableHighDpiSupport](api/DpiAware.md#enablehighdpisupport)
   * [GetSystemDpi](api/DpiAware.md#getsystemdpi)
   * [IsProcessDpiAware](api/DpiAware.md#isprocessdpiaware)
   * [SetProcessDpiAware](api/DpiAware.md#setprocessdpiaware)

api/API-index.md

@@ -209,6 +209,7 @@
 * [DownloadHandler](DownloadHandler.md#downloadhandler)
 * [DpiAware (class)](DpiAware.md#dpiaware-class)
   * [CalculateWindowSize](DpiAware.md#calculatewindowsize)
+  * [EnableHighDpiSupport](DpiAware.md#enablehighdpisupport)
   * [GetSystemDpi](DpiAware.md#getsystemdpi)
   * [IsProcessDpiAware](DpiAware.md#isprocessdpiaware)
   * [SetProcessDpiAware](DpiAware.md#setprocessdpiaware)

api/ApplicationSettings.md

@@ -84,14 +84,17 @@ all processes.
 ### auto_zooming
 
 (string)
-Windows only. Perform automatic zooming of browser contents. Example values for auto_zooming (numeric value means a zoom level):
+Windows only. Perform automatic zooming of browser contents. Example
+values for auto_zooming (numeric value means a zoom level):
 
-  * "system_dpi" - use system DPI settings, see the [DpiAware](DpiAware.md) wiki page for more details.
+  * "" - default is empty string
   * "0.0" (96 DPI)
   * "1.0" (120 DPI)
   * "2.0" (144 DPI)
   * "-1.0" (72 DPI)
-  * "" - if cefpython detects that application is DPI aware it will automatically set `auto_zooming` to "system_dpi". If you do not wish such behavior set `auto_zooming` to an empty string. See the [DpiAware](DpiAware.md) wiki page for more details on that.
+  * "system_dpi" - Deprecated. Use system DPI settings. This value is
+    deprecated, as it is no more required to set auto_zooming to this
+    value after High DPI support was enabled.
 
 Example values that can be set in Win7 DPI settings (Control Panel Appearance and Personalization Display):
 

api/DpiAware.md

@@ -12,23 +12,19 @@ Table of contents:
 * [Introduction](#introduction)
 * [Static methods](#static-methods)
   * [CalculateWindowSize](#calculatewindowsize)
+  * [EnableHighDpiSupport](#enablehighdpisupport)
   * [GetSystemDpi](#getsystemdpi)
   * [IsProcessDpiAware](#isprocessdpiaware)
   * [SetProcessDpiAware](#setprocessdpiaware)
 
 
-## Introduction
-
-By default if DPI awareness is not enabled in application, then OS performs display scaling. That causes text to look fuzzy on high DPI displays. The solution is to enable DPI awareness and use the ApplicationSettings.`auto_zooming` option. High DPI support is available only on Windows.
-
-Enabling High DPI support in app can be done by embedding a DPI awareness xml manifest in executable (see [Issue #112](../issues/112) comment #2), or by calling the `DpiAware.SetProcessDpiAware` method. Embedding xml manifest is the most reliable method. There is also an another way by writing registry key, but we won't discuss this method here.
-
-The downside of calling `SetProcessDpiAware` is that scrollbar in CEF browser is very small. This is because DPI awareness was set too late, after executable and the CEF dll was loaded. To fix that embed DPI awareness xml manifest in the .exe file.
 
-Additionally you have to set the ApplicationSettings.`auto_zomming` option to "system_dpi". This will cause browser content to be zoomed automatically using system DPI settings. On Win7 these can be set in: Control Panel > Appearance and Personalization > Display.
+## Introduction
 
-When cefpyhon detects that application is DPI aware, it will automatically set ApplicationSettings."auto_zooming" to "system_dpi". User can manually enable DPI awareness in application by going to .exe properties > Compatibility tab > and checking the box labeled "Disable display scaling on high DPI settings". If you wish to not enable auto zooming in such case then set "auto_zooming" to an empty string.
+By default if DPI awareness is not enabled in application, then OS performs display scaling. That causes text to look blurry on high DPI displays. To resolve this you have to
+ call `cef.DpiAware.EnableHighDpiSupport` method. High DPI support is available only on Windows.
 
+Enabling High DPI support in app can be done by embedding a DPI awareness xml manifest in both main executable and subprocess executable (see [Issue #112](../issues/112) comment #2), or by calling the `cef.DpiAware.EnableHighDpiSupport` method.
 
 ## Static methods
 
@@ -49,6 +45,21 @@ Calculation for DPI < 96 is not yet supported. Use
 the `GetSystemDpi` method for that.
 
 
+### EnableHighDpiSupport
+
+| | |
+| --- | --- |
+| __Return__ | void |
+
+Calling this function will set current process and subprocesses
+to be DPI aware.
+
+Description from upstream CEF:
+> Call during process startup to enable High-DPI support on Windows 7 or newer.
+> Older versions of Windows should be left DPI-unaware because they do not
+> support DirectWrite and GDI fonts are kerned very badly.
+
+
 ### GetSystemDpi
 
 | | |
@@ -90,4 +101,8 @@ On Win8 this will return True if DPI awareness is set to either "System DPI awar
 | --- | --- |
 | __Return__ | void |
 
+Calling this method is deprecated, call instead `EnableHighDpiSupport()`.
+See [Issue #358](../../../issues/358) for how the behavior changed in
+latest CEF. This method now internally calls `EnableHighDpiSupport()`.
+
 Enables DPI awareness for the running process. Embedding a DPI manifest in .exe is the prefered way, as it gives more reliable results, otherwise some display bugs may appear (discussed in the "Introduction" section on this page).

docs/Migration-guide.md

@@ -35,6 +35,7 @@ Table of contents:
 * [v55+ HTTPS cache problems on pages with certificate errors](#v55-https-cache-problems-on-pages-with-certificate-errors)
 * [v55.3+ Handlers' callbacks and other interfaces](#v553-handlers-callbacks-and-other-interfaces)
 * [v56+ MacOS 10.9+ required to run](#v56-macos-109-required-to-run)
+* [v57.1+ High DPI support on Windows](#v571-high-dpi-support-on-windows)
 
 
 
@@ -281,3 +282,16 @@ your code will definitely break, unless you've also used
 ## v56+ MacOS 10.9+ required to run
 
 CEF v55 was the last version to support MacOS 10.7.
+
+
+## v57.1+ High DPI support on Windows
+
+The `cef.DpiAware.SetProcessDpiAware` function is now deprecated.
+Use cef.DpiAware.[EnableHighDpiSupport](../api/DpiAware.md#enablehighdpisupport)
+function instead.
+
+The ApplicationSettings.[auto_zooming](../api/ApplicationSettings.md#auto_zooming)
+option should have its value set to an empty string (a default now)
+for High DPI support. In previous versions the default value was
+"system_dpi" and if you have set it explicitilly in your application,
+then you should change it to an empty string now.

examples/wxpython.py

@@ -34,9 +34,8 @@ def main():
     sys.excepthook = cef.ExceptHook  # To shutdown all CEF processes on error
     settings = {}
     if WINDOWS:
-        settings["auto_zooming"] = "system_dpi"  # High DPI support
         # noinspection PyUnresolvedReferences, PyArgumentList
-        cef.DpiAware.SetProcessDpiAware()  # Alternative is to embed manifest
+        cef.DpiAware.EnableHighDpiSupport()
     cef.Initialize(settings=settings)
     app = CefApp(False)
     app.MainLoop()

src/cefpython.pyx

@@ -666,10 +666,6 @@ def Initialize(applicationSettings=None, commandLineSwitches=None, **kwargs):
         application_settings["downloads_enabled"] = True
     if "remote_debugging_port" not in application_settings:
         application_settings["remote_debugging_port"] = 0
-    if "auto_zooming" not in application_settings:
-        IF UNAME_SYSNAME == "Windows":
-            if DpiAware.IsProcessDpiAware():
-                application_settings["auto_zooming"] = "system_dpi"
     if "app_user_model_id" in application_settings:
         g_commandLineSwitches["app-user-model-id"] =\
                 application_settings["app_user_model_id"]

src/compile_time_constants.pxi

@@ -1,3 +1,3 @@
 # This file was generated by setup.py
-DEF UNAME_SYSNAME = "Linux"
-DEF PY_MAJOR_VERSION = 2
+DEF UNAME_SYSNAME = "Windows"
+DEF PY_MAJOR_VERSION = 3

src/dpi_aware_win.pyx

@@ -37,4 +37,11 @@ class DpiAware:
 
     @staticmethod
     def SetProcessDpiAware():
-        SetProcessDpiAware()
+        """Deprecated."""
+        DpiAware.EnableHighDpiSupport()
+
+    @staticmethod
+    def EnableHighDpiSupport():
+        # This CEF function sets process to be DPI aware. This
+        # CEF func is also called in subprocesses.
+        CefEnableHighDPISupport()

src/extern/cef/cef_app.pxd

@@ -23,6 +23,8 @@ cdef extern from "include/cef_app.h":
     cdef cppclass CefApp:
         pass
 
+    cdef void CefEnableHighDPISupport() nogil
+
     cdef int CefExecuteProcess(CefMainArgs& args,
                                CefRefPtr[CefApp] application,
                                void* windows_sandbox_info

src/subprocess/cefpython_app.cpp

@@ -15,7 +15,9 @@
 #endif  // OS_WIN
 
 #ifdef BROWSER_PROCESS
-#ifdef OS_LINUX
+#ifdef OS_WIN
+#include "client_handler/dpi_aware.h"
+#elif OS_LINUX  // OS_WIN
 #include <gtk/gtk.h>
 #include <gdk/gdk.h>
 #include <gdk/gdkx.h>
@@ -175,6 +177,11 @@ void CefPythonApp::OnBeforeChildProcessLaunch(
 #ifdef BROWSER_PROCESS
     // This is included only in the Browser process, when building
     // the libcefpythonapp library.
+    if (IsProcessDpiAware()) {
+        // It is required to set DPI awareness in subprocesses
+        // as well, see Issue #358.
+        command_line->AppendSwitch("enable-high-dpi-support");
+    }
     BrowserProcessHandler_OnBeforeChildProcessLaunch(command_line);
 #endif // BROWSER_PROCESS
 

src/subprocess/main.cpp

@@ -14,6 +14,17 @@ int APIENTRY wWinMain(HINSTANCE hInstance,
 {
 	UNREFERENCED_PARAMETER(hPrevInstance);
 	UNREFERENCED_PARAMETER(lpCmdLine);
+
+	// lpCmdLine does not include program name argument, must
+	// use GetCommandLineW(). Cannot use CefCommandLine::GetGlobalCommandLine,
+	// as CEF was not yet initialized.
+	CefRefPtr<CefCommandLine> command_line = \
+	        CefCommandLine::CreateCommandLine();
+    command_line->InitFromString(GetCommandLineW());
+    if (command_line->HasSwitch("enable-high-dpi-support")) {
+	    CefEnableHighDPISupport();
+	}
+
 	CefMainArgs mainArgs(hInstance);
 
 #else // defined(OS_WIN)