Multiple DPI Tracking for ScreenWin

ui/gfx/screen_win.cc

Index: ui/gfx/screen_win.cc
diff --git a/ui/gfx/screen_win.cc b/ui/gfx/screen_win.cc
index 46bce435e742d3afa9d99a2ff3c87a331d3be19a..32326a45f8afd88b150f283efb8e8079f60395f4 100644
--- a/ui/gfx/screen_win.cc
+++ b/ui/gfx/screen_win.cc
@@ -10,17 +10,96 @@
 #include "base/bind_helpers.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/geometry/point.h"
+#include "ui/gfx/geometry/point_conversions.h"
 #include "ui/gfx/geometry/rect.h"
+#include "ui/gfx/geometry/size.h"
+#include "ui/gfx/geometry/vector2d.h"
 #include "ui/gfx/win/display_info.h"
 #include "ui/gfx/win/dpi.h"
+#include "ui/gfx/win/rect_util.h"
 #include "ui/gfx/win/screen_win_display.h"
 
 namespace {
 
+gfx::ScreenWin* g_screen_win_instance = nullptr;
+
+std::vector<gfx::win::DisplayInfo>::const_iterator FindTouchingDisplayInfo(
+    const gfx::win::ScreenWinDisplay& screen_win_display,
+    const std::vector<gfx::win::DisplayInfo>& display_infos) {
+  auto end = display_infos.end();
+  for (auto display_info_iter = display_infos.begin();
+       display_info_iter != end;
+       display_info_iter++) {
+    gfx::win::RectEdge edge =
+        gfx::win::FindTouchingRectEdge(screen_win_display.pixel_bounds(),
+                                       display_info_iter->screen_rect());
+    if (edge != gfx::win::RectEdge::NONE)
+      return display_info_iter;
+  }
+  return end;
+}
+
+// Windows historically has had a hard time handling displays of DPIs higher
+// than 96. Handling multiple DPI displays means we have to deal with Windows'
+// monitor physical coordinates and map into Chrome's DIP coordinates.
+//
+// To do this, DisplayInfosToScreenWinDisplays reasons over monitors as a tree
+// using the primary monitor as the root. Any monitor touching this root is
+// considered a child. Subsequent generations are formed similarly, having
+// preferring parents that are discovered earlier. As a result, if there is a
+// monitor that touches two other monitors, the earliest discovered monitor is
+// the parent.
+//
+// This also presumes that all monitors are connected components. Windows, by UI
+// construction restricts the layout of monitors to connected components except
+// when DPI virtualization is happening. When this happens, we scale relative
+// to (0, 0) like before.
+//
+// All subsequent scaling transformations are performed with respect to the
+// calculated physical-DIP mapping on ScreenWinDisplay.
+//
+// Note that this does not handle cases where a scaled display may have
+// insufficient room to lay out its children. In these cases, a DIP point could
+// map to multiple screen points due to overlap. The first discovered screen
+// will take precedence.
 std::vector<gfx::win::ScreenWinDisplay> DisplayInfosToScreenWinDisplays(
     const std::vector<gfx::win::DisplayInfo>& display_infos) {
+  std::vector<gfx::win::DisplayInfo> display_infos_remaining = display_infos;
+
+  // Seed the primary display to layout all the other displays.
   std::vector<gfx::win::ScreenWinDisplay> screen_win_displays;
-  for (const auto& display_info : display_infos)
+  for (auto current = display_infos_remaining.begin();
+       current != display_infos_remaining.end();
+       current++) {
+    if (current->screen_rect().origin().IsOrigin()) {
+      screen_win_displays.push_back(gfx::win::ScreenWinDisplay(*current));
+      display_infos_remaining.erase(current);
+      break;
+    }
+  }
+
+  // Scale touching display_infos relative to each other.
+  // If the DisplayInfo count doesn't change through one cycle of the loop, it
+  // either means we're done or we have non-touching DisplayInfos in the vector.
+  size_t display_infos_at_cycle_start = 0;
+  while ((display_infos_remaining.size() > 0) &&
+         (display_infos_remaining.size() != display_infos_at_cycle_start)) {
+    display_infos_at_cycle_start = display_infos_remaining.size();
+    for (const auto& screen_win_display : screen_win_displays) {
+      auto display_info = FindTouchingDisplayInfo(screen_win_display,
+                                                  display_infos_remaining);
+      if (display_info != display_infos_remaining.end()) {
+        screen_win_displays.push_back(
+            gfx::win::ScreenWinDisplay(screen_win_display, *display_info));
+        display_infos_remaining.erase(display_info);
+        break;
+      }
+    }
+  }
+
+  // Under Windows DPI virtualization, not all display_infos touch, so scale
+  // the remaining display infos relative to the origin.
+  for (const auto& display_info : display_infos_remaining)
     screen_win_displays.push_back(gfx::win::ScreenWinDisplay(display_info));
 
   return screen_win_displays;
@@ -65,15 +144,119 @@ std::vector<gfx::win::DisplayInfo> GetDisplayInfosFromSystem() {
   return display_infos;
 }
 
+// Returns a point in |to_origin|'s coordinates and position scaled by
+// |scale_factor|.
+gfx::Point ScalePointRelative(const gfx::Point& from_origin,
+                              const gfx::Point& to_origin,
+                              const float scale_factor,
+                              const gfx::Point& point) {
+  gfx::Vector2d from_origin_vector(from_origin.x(), from_origin.y());
+  gfx::Vector2d to_origin_vector(to_origin.x(), to_origin.y());
+  gfx::Point scaled_relative_point(
+      gfx::ScaleToFlooredPoint(point - from_origin_vector, scale_factor));
+  return scaled_relative_point + to_origin_vector;
+}
+
 }  // namespace
 
 namespace gfx {
 
 ScreenWin::ScreenWin() {
+  DCHECK(!g_screen_win_instance);
+  g_screen_win_instance = this;
   Initialize();
 }
 
-ScreenWin::~ScreenWin() = default;
+ScreenWin::~ScreenWin() {
+  DCHECK(g_screen_win_instance == this);
+  g_screen_win_instance = nullptr;
+}
+
+// static
+Point ScreenWin::ScreenToDIPPoint(const Point& pixel_point) {
+  const gfx::win::ScreenWinDisplay screen_win_display =
+      ScreenWin::GetScreenWinDisplayVia(
+          &ScreenWin::GetScreenWinDisplayNearestScreenPoint, pixel_point);
+  const Display display = screen_win_display.display();
+  return ScalePointRelative(screen_win_display.pixel_bounds().origin(),
+                            display.bounds().origin(),
+                            1.0f / display.device_scale_factor(),
+                            pixel_point);
+}
+
+// static
+Point ScreenWin::DIPToScreenPoint(const Point& dip_point) {
+  const gfx::win::ScreenWinDisplay screen_win_display =
+      ScreenWin::GetScreenWinDisplayVia(
+          &ScreenWin::GetScreenWinDisplayNearestDIPPoint, dip_point);
+  const Display display = screen_win_display.display();
+  return ScalePointRelative(display.bounds().origin(),
+                            screen_win_display.pixel_bounds().origin(),
+                            display.device_scale_factor(),
+                            dip_point);
+}
+
+// static
+Point ScreenWin::ClientToDIPPoint(HWND hwnd, const Point& client_point) {
+  const float scale_factor = ScreenWin::GetScaleFactorForHWND(hwnd);
+  return ScaleToFlooredPoint(client_point, 1.0f / scale_factor);
+}
+
+// static
+Point ScreenWin::DIPToClientPoint(HWND hwnd, const Point& dip_point) {
+  float scale_factor = ScreenWin::GetScaleFactorForHWND(hwnd);
+  return ScaleToFlooredPoint(dip_point, scale_factor);
+}
+
+// static
+Rect ScreenWin::ScreenToDIPRect(HWND hwnd, const Rect& pixel_bounds) {
+  float scale_factor = hwnd ?
+      ScreenWin::GetScaleFactorForHWND(hwnd) :
+      ScreenWin::GetScreenWinDisplayVia(
+          &ScreenWin::GetScreenWinDisplayNearestScreenRect, pixel_bounds).
+              display().device_scale_factor();
+  gfx::Rect dip_rect = ScaleToEnclosingRect(pixel_bounds, 1.0f / scale_factor);
+  dip_rect.set_origin(ScreenWin::ScreenToDIPPoint(pixel_bounds.origin()));
+  return dip_rect;
+}
+
+// static
+Rect ScreenWin::DIPToScreenRect(HWND hwnd, const Rect& dip_bounds) {
+  float scale_factor = hwnd ?
+      ScreenWin::GetScaleFactorForHWND(hwnd) :
+      ScreenWin::GetScreenWinDisplayVia(
+          &ScreenWin::GetScreenWinDisplayNearestDIPRect, dip_bounds).
+              display().device_scale_factor();
+  gfx::Rect screen_rect = ScaleToEnclosingRect(dip_bounds, scale_factor);
+  screen_rect.set_origin(ScreenWin::DIPToScreenPoint(dip_bounds.origin()));
+  return screen_rect;
+}
+
+// static
+Rect ScreenWin::ClientToDIPRect(HWND hwnd, const Rect& pixel_bounds) {
+  float scale_factor = ScreenWin::GetScaleFactorForHWND(hwnd);
+  return ScaleToEnclosingRect(pixel_bounds, 1.0f / scale_factor);
+}
+
+// static
+Rect ScreenWin::DIPToClientRect(HWND hwnd, const Rect& dip_bounds) {
+  float scale_factor = ScreenWin::GetScaleFactorForHWND(hwnd);
+  return ScaleToEnclosingRect(dip_bounds, scale_factor);
+}
+
+// static
+Size ScreenWin::ScreenToDIPSize(HWND hwnd, const Size& size_in_pixels) {
+  float scale_factor = ScreenWin::GetScaleFactorForHWND(hwnd);
+  // Always ceil sizes. Otherwise we may be leaving off part of the bounds.
+  return ScaleToCeiledSize(size_in_pixels, 1.0f / scale_factor);
+}
+
+// static
+Size ScreenWin::DIPToScreenSize(HWND hwnd, const Size& dip_size) {
+  float scale_factor = ScreenWin::GetScaleFactorForHWND(hwnd);
+  // Always ceil sizes. Otherwise we may be leaving off part of the bounds.
+  return ScaleToCeiledSize(dip_size, scale_factor);
+}
 
 HWND ScreenWin::GetHWNDFromNativeView(NativeView window) const {
   NOTREACHED();
@@ -89,7 +272,7 @@ gfx::Point ScreenWin::GetCursorScreenPoint() {
   POINT pt;
   ::GetCursorPos(&pt);
   gfx::Point cursor_pos_pixels(pt);
-  return gfx::win::ScreenToDIPPoint(cursor_pos_pixels);
+  return ScreenWin::ScreenToDIPPoint(cursor_pos_pixels);
 }
 
 gfx::NativeWindow ScreenWin::GetWindowUnderCursor() {
@@ -100,7 +283,7 @@ gfx::NativeWindow ScreenWin::GetWindowUnderCursor() {
 }
 
 gfx::NativeWindow ScreenWin::GetWindowAtScreenPoint(const gfx::Point& point) {
-  gfx::Point point_in_pixels = gfx::win::DIPToScreenPoint(point);
+  gfx::Point point_in_pixels = ScreenWin::DIPToScreenPoint(point);
   return GetNativeWindowFromHWND(WindowFromPoint(point_in_pixels.ToPOINT()));
 }
 
@@ -126,7 +309,7 @@ gfx::Display ScreenWin::GetDisplayNearestWindow(gfx::NativeView window) const {
 }
 
 gfx::Display ScreenWin::GetDisplayNearestPoint(const gfx::Point& point) const {
-  gfx::Point screen_point(gfx::win::DIPToScreenPoint(point));
+  gfx::Point screen_point(ScreenWin::DIPToScreenPoint(point));
   gfx::win::ScreenWinDisplay screen_win_display =
       GetScreenWinDisplayNearestScreenPoint(screen_point);
   return screen_win_display.display();
@@ -150,6 +333,18 @@ void ScreenWin::RemoveObserver(DisplayObserver* observer) {
   change_notifier_.RemoveObserver(observer);
 }
 
+gfx::Rect ScreenWin::ScreenToDIPRectInWindow(
+    NativeView view, const gfx::Rect& screen_rect) const {
+  HWND hwnd = view ? GetHWNDFromNativeView(view) : nullptr;
+  return ScreenWin::ScreenToDIPRect(hwnd, screen_rect);
+}
+
+gfx::Rect ScreenWin::DIPToScreenRectInWindow(NativeView view,
+                                             const gfx::Rect& dip_rect) const {
+  HWND hwnd = view ? GetHWNDFromNativeView(view) : nullptr;
+  return ScreenWin::DIPToScreenRect(hwnd, dip_rect);
+}
+
 void ScreenWin::UpdateFromDisplayInfos(
     const std::vector<gfx::win::DisplayInfo>& display_infos) {
   screen_win_displays_ = DisplayInfosToScreenWinDisplays(display_infos);
@@ -213,6 +408,39 @@ gfx::win::ScreenWinDisplay ScreenWin::GetScreenWinDisplayNearestScreenPoint(
   return GetScreenWinDisplay(MonitorInfoFromScreenPoint(screen_point));
 }
 
+gfx::win::ScreenWinDisplay ScreenWin::GetScreenWinDisplayNearestDIPPoint(
+    const Point& dip_point) const {
+  gfx::win::ScreenWinDisplay primary_screen_win_display;
+  for (const auto& screen_win_display : screen_win_displays_) {
+    Display display = screen_win_display.display();
+    const gfx::Rect dip_bounds = display.bounds();
+    if (dip_bounds.Contains(dip_point))
+      return screen_win_display;
+    else if (dip_bounds.origin().IsOrigin())
+      primary_screen_win_display = screen_win_display;
+  }
+  return primary_screen_win_display;
+}
+
+gfx::win::ScreenWinDisplay ScreenWin::GetScreenWinDisplayNearestDIPRect(
+    const Rect& dip_rect) const {
+  gfx::win::ScreenWinDisplay closest_screen_win_display;
+  int64_t closest_distance_squared = INT64_MAX;
+  for (const auto& screen_win_display : screen_win_displays_) {
+    Display display = screen_win_display.display();
+    gfx::Rect dip_bounds = display.bounds();
+    int64_t distance_squared =
+        gfx::win::SquaredDistanceBetweenRects(dip_rect, dip_bounds);
+    if (distance_squared == 0) {
+      return screen_win_display;
+    } else if (distance_squared < closest_distance_squared) {
+      closest_distance_squared = distance_squared;
+      closest_screen_win_display = screen_win_display;
+    }
+  }
+  return closest_screen_win_display;
+}
+
 gfx::win::ScreenWinDisplay ScreenWin::GetPrimaryScreenWinDisplay() const {
   MONITORINFOEX monitor_info = MonitorInfoFromWindow(nullptr,
                                                      MONITOR_DEFAULTTOPRIMARY);
@@ -240,4 +468,26 @@ gfx::win::ScreenWinDisplay ScreenWin::GetScreenWinDisplay(
   return gfx::win::ScreenWinDisplay();
 }
 
+// static
+float ScreenWin::GetScaleFactorForHWND(HWND hwnd) {
+  if (!g_screen_win_instance)
+    return gfx::win::ScreenWinDisplay().display().device_scale_factor();
+
+  DCHECK(hwnd);
+  HWND rootHwnd = g_screen_win_instance->GetRootWindow(hwnd);
+  gfx::win::ScreenWinDisplay screen_win_display =
+      g_screen_win_instance->GetScreenWinDisplayNearestHWND(rootHwnd);
+  return screen_win_display.display().device_scale_factor();
+}
+
+// static
+template <typename Getter, typename GetterType>
+gfx::win::ScreenWinDisplay ScreenWin::GetScreenWinDisplayVia(Getter getter,
+                                                             GetterType value) {
+  if (!g_screen_win_instance)
+    return gfx::win::ScreenWinDisplay();
+
+  return (g_screen_win_instance->*getter)(value);
+}
+
 }  // namespace gfx