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   // WM_GETTITLEBARINFOEX returns rects in screen coordinates in pixels.
  31   // We need to convert the minimize button corner offset to DIP before
  32   // returning it.
  33   POINT minimize_button_corner = { titlebar_info.rgrect[2].left, 0 };
  34   MapWindowPoints(HWND_DESKTOP, hwnd, &minimize_button_corner, 1);
  35   return minimize_button_corner.x / gfx::GetDPIScale();
  36 }
  37
  38 }  // namespace
  39
  40 // static
  41 int MinimizeButtonMetrics::last_cached_minimize_button_x_delta_ = 0;
  42
  43 MinimizeButtonMetrics::MinimizeButtonMetrics()
  44     : hwnd_(nullptr),
  45       cached_minimize_button_x_delta_(last_cached_minimize_button_x_delta_),
  46       was_activated_(false) {
  47 }
  48
  49 MinimizeButtonMetrics::~MinimizeButtonMetrics() {
  50 }
  51
  52 void MinimizeButtonMetrics::Init(HWND hwnd) {
  53   DCHECK(!hwnd_);
  54   hwnd_ = hwnd;
  55 }
  56
  57 void MinimizeButtonMetrics::OnHWNDActivated() {
  58   was_activated_ = true;
  59   // NOTE: we don't cache here as it seems only after the activate is the value
  60   // correct.
  61 }
  62
  63 int MinimizeButtonMetrics::GetMinimizeButtonOffsetX() const {
  64   // Under DWM WM_GETTITLEBARINFOEX won't return the right thing until after
  65   // WM_NCACTIVATE (maybe it returns classic values?). In an attempt to return a
  66   // consistant value we cache the last value across instances and use it until
  67   // we get the activate.
  68   if (was_activated_ || !ui::win::IsAeroGlassEnabled() ||
  69       cached_minimize_button_x_delta_ == 0) {
  70     const int minimize_button_offset = GetAndCacheMinimizeButtonOffsetX();
  71     if (minimize_button_offset > 0)
  72       return minimize_button_offset;
  73   }
  74
  75   // If we fail to get the minimize button offset via the WM_GETTITLEBARINFOEX
  76   // message then calculate and return this via the
  77   // cached_minimize_button_x_delta_ member value. Please see
  78   // CacheMinimizeButtonDelta() for more details.
  79   DCHECK(cached_minimize_button_x_delta_);
  80
  81   if (base::i18n::IsRTL())
  82     return cached_minimize_button_x_delta_;
  83
  84   RECT client_rect = {0};
  85   GetClientRect(hwnd_, &client_rect);
  86   return client_rect.right - cached_minimize_button_x_delta_;
  87 }
  88
  89 int MinimizeButtonMetrics::GetAndCacheMinimizeButtonOffsetX() const {
  90   const int minimize_button_offset = GetMinimizeButtonOffsetForWindow(hwnd_);
  91   if (minimize_button_offset <= 0)
  92     return 0;
  93
  94   if (base::i18n::IsRTL()) {
  95     cached_minimize_button_x_delta_ = minimize_button_offset;
  96   } else {
  97     RECT client_rect = {0};
  98     GetClientRect(hwnd_, &client_rect);
  99     cached_minimize_button_x_delta_ =
 100         client_rect.right - minimize_button_offset;
 101   }
 102   last_cached_minimize_button_x_delta_ = cached_minimize_button_x_delta_;
 103   return minimize_button_offset;
 104 }