Fix touch scaling for high dpi windows.

Fix touch scaling for high dpi windows.

Touch events in windows are always expressed in screen coordinates, even if
the target app is not dpi-aware. This patch determines the dpi scale used
by the OS, and re-scales touch events accordingly. 

In some cases the touch events are sent to the wrong window. This is detected
and corrected.

BUG=175542
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=185474

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=186187

[girard, 2013-02-28 18:22:13]

Until we become High-DPI aware, we need to correct touch coordinates. (The OS
auto-scales most things, like mouse events and window sizes, but it does _not_
auto-scale touches.)

[sky, 2013-02-28 21:43:06]

LGTM

[girard, 2013-02-28 22:05:43]

On 2013/02/28 21:43:06, sky wrote:
> LGTM

Thanks, Sky.  Minor addition - it turns out that in "metro mode", the app is
flagged as DPI aware, and so the fix isn't needed there. (Took me a while to get
a valid test image installed under Metro). Patch #3 tests for being DPI-aware
before it enables touch-scaling.

Can you please review the delta? (Sorry for the noise.)

[sky, 2013-02-28 22:22:23]

SLGTM

[commit-bot: I haz the power, 2013-03-01 04:35:36]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/girard@chromium.org/12317157/5005

[commit-bot: I haz the power, 2013-03-01 07:21:06]

Change committed as 185474

[girard, 2013-03-04 18:52:55]

On 2013/03/01 07:21:06, I haz the power (commit-bot) wrote:
> Change committed as 185474

Change was reverted in https://codereview.chromium.org/12379040/ because of
breakage on the XP bots. I've tested on XP, and confirmed through inspection
that this code can't possibly run on XP (in chrome, or in a unit test), so this
must be a flaky test result.  Re-trying the patch.

[commit-bot: I haz the power, 2013-03-04 18:53:20]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/girard@chromium.org/12317157/5005

[commit-bot: I haz the power, 2013-03-04 18:53:21]

Failed to apply patch for ui/base/win/dpi.cc:
While running patch -p1 --forward --force --no-backup-if-mismatch;
  patching file ui/base/win/dpi.cc
  Hunk #1 FAILED at 7.
  Hunk #2 succeeded at 30 (offset 3 lines).
  Hunk #3 succeeded at 113 (offset 3 lines).
  1 out of 3 hunks FAILED -- saving rejects to file ui/base/win/dpi.cc.rej

Patch:       ui/base/win/dpi.cc
Index: ui/base/win/dpi.cc
diff --git a/ui/base/win/dpi.cc b/ui/base/win/dpi.cc
index
ecfb3e7a31e477ff93b3e4a19394bd2d6ced2d09..222b61f14784b1b60451cefd2d85bf752b9bf961
100644
--- a/ui/base/win/dpi.cc
+++ b/ui/base/win/dpi.cc
@@ -7,6 +7,7 @@
 #include <windows.h>
 
 #include "base/win/scoped_hdc.h"
+#include "base/win/registry.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/point_conversions.h"
 #include "ui/gfx/rect_conversions.h"
@@ -27,6 +28,16 @@ float GetDeviceScaleFactorImpl() {
 #endif
 }
 
+BOOL IsProcessDPIAwareWrapper() {
+  typedef BOOL(WINAPI *IsProcessDPIAwarePtr)(VOID);
+  IsProcessDPIAwarePtr is_process_dpi_aware_func =
+      reinterpret_cast<IsProcessDPIAwarePtr>(
+          GetProcAddress(GetModuleHandleA("user32.dll"), "IsProcessDPIAware"));
+  if (is_process_dpi_aware_func)
+    return is_process_dpi_aware_func();
+  return FALSE;
+}
+
 }  // namespace
 
 namespace ui {
@@ -100,6 +111,28 @@ gfx::Size DIPToScreenSize(const gfx::Size& dip_size) {
   return gfx::ToFlooredSize(gfx::ScaleSize(dip_size, GetDeviceScaleFactor()));
 }
 
+double GetDPIScaleFromRegistry() {
+  static double scale = -1.0;
+  if (scale == -1.0) {
+    double result = 1.0;
+    if (!IsProcessDPIAwareWrapper()) {
+      //HKEY_CURRENT_USER\Control Panel\Desktop\WindowMetrics\AppliedDPI
+      base::win::RegKey key(HKEY_CURRENT_USER,
+                            L"Control Panel\\Desktop\\WindowMetrics",
+                            KEY_QUERY_VALUE);
+
+      if (key.Valid()) {
+        DWORD value = 0;
+        if (key.ReadValueDW(L"AppliedDPI", &value) == ERROR_SUCCESS) {
+          result = ((double)value) / kDefaultDPIX;
+        }
+      }
+    }
+    scale = result;
+  }
+  return scale;
+}
+
 }  // namespace win
 
 }  // namespace ui

[commit-bot: I haz the power, 2013-03-05 13:55:10]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/girard@chromium.org/12317157/7004

[commit-bot: I haz the power, 2013-03-05 16:43:27]

Change committed as 186187

[Ryan Sleevi, 2013-03-05 18:32:56]

drive by comments and nits.

Note: You should open a new issue (git cl issue 0), upload the
existing-as-landed, then upload the fixed version, and have that landed. You
should not re-use the same codereview CL to land the same patch multiple times.

https://chromiumcodereview.appspot.com/12317157/diff/7004/ui/base/win/dpi.cc
File ui/base/win/dpi.cc (right):

https://chromiumcodereview.appspot.com/12317157/diff/7004/ui/base/win/dpi.cc#...
ui/base/win/dpi.cc:130: //HKEY_CURRENT_USER\Control
Panel\Desktop\WindowMetrics\AppliedDPI
nit: space between //

https://chromiumcodereview.appspot.com/12317157/diff/7004/ui/base/win/dpi.cc#...
ui/base/win/dpi.cc:138: result = ((double)value) / kDefaultDPIX;
style: Don't do C-casts

https://chromiumcodereview.appspot.com/12317157/diff/7004/ui/base/win/hwnd_su...
File ui/base/win/hwnd_subclass.cc (right):

https://chromiumcodereview.appspot.com/12317157/diff/7004/ui/base/win/hwnd_su...
ui/base/win/hwnd_subclass.cc:131: &point, sizeof(TOUCHINPUT))) {
style: indentation
BUG: GetTouchInputInfo is only available on Win7+. You need to
GetProcAdress-wrap this function