linux_aura: Enable HIDPI support

ui/views/widget/desktop_aura/desktop_screen_x11.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/widget/desktop_aura/desktop_screen_x11.h"
 
 #include <X11/extensions/Xrandr.h>
 #include <X11/Xlib.h>
 
 // It clashes with out RootWindow.
 #undef RootWindow
 
 #include "base/logging.h"
 #include "base/x11/edid_parser_x11.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/root_window_host.h"
+#include "ui/base/layout.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/display_observer.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/screen.h"
 #include "ui/gfx/x/x11_types.h"
 #include "ui/views/widget/desktop_aura/desktop_root_window_host_x11.h"
 #include "ui/views/widget/desktop_aura/desktop_screen.h"
 
 namespace {
 
 // The delay to perform configuration after RRNotify.  See the comment
 // in |Dispatch()|.
 const int64 kConfigureDelayMs = 500;
 
+float GetDeviceScaleFactor(int screen_dimention, int mm_screen_dimention) {

[Daniel Erat, 2013/10/29 16:27:03]

s/dimention/dimension/g

the units of the first argument are ambiguous -- if it's pixels, could you
rename these to something like "screen_pixels" and "screen_mm"?

+  const int kCSSDefaultDIPCountPerInch = 96;

[Daniel Erat, 2013/10/29 16:27:03]

is something shorter like kCSSDefaultDPI still accurate? feel free to ignore
this suggestion if you want to keep DIP in the name.

+  const float kInchInMm = 25.4f;
+
+  float screen_dpi = (screen_dimention * kInchInMm) / mm_screen_dimention;

[Daniel Erat, 2013/10/29 16:27:03]

maybe a bit clearer:

  float screen_inches = screen_mm / kInchInMm;
  float screen_dpi = screen_pixels / screen_inches;

+  float scale = screen_dpi / kCSSDefaultDIPCountPerInch;
+
+  return ui::GetImageScale(ui::GetSupportedScaleFactor(scale));
+}
+
 std::vector<gfx::Display> GetFallbackDisplayList() {
   ::XDisplay* display = gfx::GetXDisplay();
   ::Screen* screen = DefaultScreenOfDisplay(display);
   int width = WidthOfScreen(screen);
   int height = HeightOfScreen(screen);
+  int mm_width = WidthMMOfScreen(screen);
+  int mm_height = HeightMMOfScreen(screen);
 
-  return std::vector<gfx::Display>(
-      1, gfx::Display(0, gfx::Rect(0, 0, width, height)));
+  gfx::Rect bounds_in_pixels(0, 0, width, height);
+  gfx::Display gfx_display(0, bounds_in_pixels);
+  if (!gfx::Display::HasForceDeviceScaleFactor() &&
+      !ui::IsXDisplaySizeBlackListed(mm_width, mm_height)) {
+    float device_scale_factor = GetDeviceScaleFactor(width, mm_width);
+    DCHECK_LE(1.0f, device_scale_factor);
+    gfx_display.SetScaleAndBounds(device_scale_factor, bounds_in_pixels);
+  }
+
+  return std::vector<gfx::Display>(1, gfx_display);
 }
 
 }  // namespace
 
 namespace views {
 
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopScreenX11, public:
 
 DesktopScreenX11::DesktopScreenX11()
@@ skipping 71 matching lines @@
     }
   }
 
   displays_ = incoming;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopScreenX11, gfx::Screen implementation:
 
 bool DesktopScreenX11::IsDIPEnabled() {
-  return false;
+  return true;
 }
 
 gfx::Point DesktopScreenX11::GetCursorScreenPoint() {
   XDisplay* display = gfx::GetXDisplay();
 
   ::Window root, child;
   int root_x, root_y, win_x, win_y;
   unsigned int mask;
   XQueryPointer(display,
                 DefaultRootWindow(display),
@@ skipping 143 matching lines @@
 
   bool has_work_area = false;
   gfx::Rect work_area;
   std::vector<int> value;
   if (ui::GetIntArrayProperty(x_root_window_, "_NET_WORKAREA", &value) &&
       value.size() >= 4) {
     work_area = gfx::Rect(value[0], value[1], value[2], value[3]);
     has_work_area = true;
   }
 
+  float device_scale_factor = 1.0f;
   for (int i = 0; i < resources->noutput; ++i) {
     RROutput output_id = resources->outputs[i];
     XRROutputInfo* output_info =
         XRRGetOutputInfo(xdisplay_, resources, output_id);
 
     bool is_connected = (output_info->connection == RR_Connected);
     if (!is_connected) {
       XRRFreeOutputInfo(output_info);
       continue;
     }
 
     if (output_info->crtc) {
       XRRCrtcInfo *crtc = XRRGetCrtcInfo(xdisplay_,
                                          resources,
                                          output_info->crtc);
 
       int64 display_id = -1;
       if (!base::GetDisplayId(output_id, i, &display_id)) {
         // It isn't ideal, but if we can't parse the EDID data, fallback on the
         // display number.
         display_id = i;
       }
 
       gfx::Rect crtc_bounds(crtc->x, crtc->y, crtc->width, crtc->height);
       gfx::Display display(display_id, crtc_bounds);
+
+      if (!gfx::Display::HasForceDeviceScaleFactor()) {
+        if (i == 0 && !ui::IsXDisplaySizeBlackListed(output_info->mm_width,
+                                                     output_info->mm_height)) {
+          // As per display scale factor is not supported right now,
+          // the primary display's scale factor is always used.
+          device_scale_factor = GetDeviceScaleFactor(crtc->width,
+                                                       output_info->mm_width);
+          DCHECK_LE(1.0f, device_scale_factor);
+        }
+        display.SetScaleAndBounds(device_scale_factor, crtc_bounds);
+      }
+
       if (has_work_area) {
         gfx::Rect intersection = crtc_bounds;
         intersection.Intersect(work_area);
         display.set_work_area(intersection);
       }
 
       displays.push_back(display);
 
       XRRFreeCrtcInfo(crtc);
     }
@@ skipping 14 matching lines @@
   ProcessDisplayChange(new_displays);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 
 gfx::Screen* CreateDesktopScreen() {
   return new DesktopScreenX11;
 }
 
 }  // namespace views