chrome/browser/ui/views/frame/minimize_button_metrics_win.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/ui/views/frame/minimize_button_metrics_win.h"
   6
   7 #include "base/logging.h"
   8 #include "base/i18n/rtl.h"
   9 #include "ui/base/win/shell.h"
  10 #include "ui/gfx/win/dpi.h"
  11
  12 namespace {
  13
  14 int GetMinimizeButtonOffsetForWindow(HWND hwnd) {
  15   // The WM_GETTITLEBARINFOEX message can fail if we are not active/visible. By
  16   // fail we get a location of 0; the return status code is always the same and
  17   // similarly the state never seems to change (titlebar_info.rgstate).
  18   TITLEBARINFOEX titlebar_info = {0};
  19   titlebar_info.cbSize = sizeof(TITLEBARINFOEX);
  20   SendMessage(hwnd, WM_GETTITLEBARINFOEX, 0,
  21               reinterpret_cast<WPARAM>(&titlebar_info));
  22
  23   if (titlebar_info.rgrect[2].left == titlebar_info.rgrect[2].right ||
  24       (titlebar_info.rgstate[2] & (STATE_SYSTEM_INVISIBLE |
  25                                    STATE_SYSTEM_OFFSCREEN |
  26                                    STATE_SYSTEM_UNAVAILABLE))) {
  27     return 0;
  28   }
  29
  30   // Most versions of Windows return screen coordinates for
  31   // WM_GETTITLEBARINFOEX. Since chrome is not dpi aware (currently) we need to
  32   // unscale these coordinates. Surface Pro seems to be unique, in that it
  33   // returns local coordinates (eg they don't need to be scaled). There doesn't
  34   // appear to be a clear way to detect this, so we assume that if the minimize
  35   // button is outside the bounds of the window coordinates are scaled.
  36   RECT window_rect = {0};
  37   GetWindowRect(hwnd, &window_rect);
  38   POINT minimize_button_corner = { titlebar_info.rgrect[2].left, 0 };
  39   if (minimize_button_corner.x > window_rect.right) {
  40     minimize_button_corner.x =
  41         static_cast<int>(minimize_button_corner.x /
  42                          gfx::win::GetUndocumentedDPIScale());
  43   }
  44   MapWindowPoints(HWND_DESKTOP, hwnd, &minimize_button_corner, 1);
  45   return minimize_button_corner.x / gfx::win::GetDeviceScaleFactor();
  46 }
  47
  48 }  // namespace
  49
  50 // static
  51 int MinimizeButtonMetrics::last_cached_minimize_button_x_delta_ = 0;
  52
  53 MinimizeButtonMetrics::MinimizeButtonMetrics()
  54     : hwnd_(NULL),
  55       cached_minimize_button_x_delta_(last_cached_minimize_button_x_delta_),
  56       was_activated_(false) {
  57 }
  58
  59 MinimizeButtonMetrics::~MinimizeButtonMetrics() {
  60 }
  61
  62 void MinimizeButtonMetrics::Init(HWND hwnd) {
  63   DCHECK(!hwnd_);
  64   hwnd_ = hwnd;
  65 }
  66
  67 void MinimizeButtonMetrics::OnHWNDActivated() {
  68   was_activated_ = true;
  69   // NOTE: we don't cache here as it seems only after the activate is the value
  70   // correct.
  71 }
  72
  73 int MinimizeButtonMetrics::GetMinimizeButtonOffsetX() const {
  74   // Under DWM WM_GETTITLEBARINFOEX won't return the right thing until after
  75   // WM_NCACTIVATE (maybe it returns classic values?). In an attempt to return a
  76   // consistant value we cache the last value across instances and use it until
  77   // we get the activate.
  78   if (was_activated_ || !ui::win::IsAeroGlassEnabled() ||
  79       cached_minimize_button_x_delta_ == 0) {
  80     const int minimize_button_offset = GetAndCacheMinimizeButtonOffsetX();
  81     if (minimize_button_offset > 0)
  82       return minimize_button_offset;
  83   }
  84
  85   // If we fail to get the minimize button offset via the WM_GETTITLEBARINFOEX
  86   // message then calculate and return this via the
  87   // cached_minimize_button_x_delta_ member value. Please see
  88   // CacheMinimizeButtonDelta() for more details.
  89   DCHECK(cached_minimize_button_x_delta_);
  90
  91   if (base::i18n::IsRTL())
  92     return cached_minimize_button_x_delta_;
  93
  94   RECT client_rect = {0};
  95   GetClientRect(hwnd_, &client_rect);
  96   return client_rect.right - cached_minimize_button_x_delta_;
  97 }
  98
  99 int MinimizeButtonMetrics::GetAndCacheMinimizeButtonOffsetX() const {
 100   const int minimize_button_offset = GetMinimizeButtonOffsetForWindow(hwnd_);
 101   if (minimize_button_offset <= 0)
 102     return 0;
 103
 104   if (base::i18n::IsRTL()) {
 105     cached_minimize_button_x_delta_ = minimize_button_offset;
 106   } else {
 107     RECT client_rect = {0};
 108     GetClientRect(hwnd_, &client_rect);
 109     cached_minimize_button_x_delta_ =
 110         client_rect.right - minimize_button_offset;
 111   }
 112   last_cached_minimize_button_x_delta_ = cached_minimize_button_x_delta_;
 113   return minimize_button_offset;
 114 }