ui/views/corewm/cursor_height_provider_win.cc

   1 // Copyright 2014 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 "ui/views/corewm/cursor_height_provider_win.h"
   6
   7 #include <windows.h>
   8 #include <algorithm>
   9 #include <map>
  10
  11 #include "base/basictypes.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/win/scoped_hdc.h"
  14
  15 namespace {
  16 typedef scoped_ptr<uint32_t> PixelData;
  17 typedef std::map<HCURSOR, int> HeightStorage;
  18
  19 const uint32_t kBitsPeruint32 = sizeof(uint32_t) * 8;
  20 // All bits are 1 for transparent portion of monochromatic mask.
  21 const uint32_t kTransparentMask = 0xffffffff;
  22 // This is height of default pointer arrow in Windows 7.
  23 const int kDefaultHeight = 20;
  24 // Masks are monochromatic.
  25 const size_t kNumberOfColors = 2;
  26 const size_t KHeaderAndPalette =
  27       sizeof(BITMAPINFOHEADER) + kNumberOfColors * sizeof(RGBQUAD);
  28
  29 static HeightStorage* cached_heights = NULL;
  30
  31 // Extracts the pixel data of provided bitmap
  32 PixelData GetBitmapData(HBITMAP handle, const BITMAPINFO& info, HDC hdc) {
  33   PixelData data;
  34   // Masks are monochromatic.
  35   DCHECK_EQ(info.bmiHeader.biBitCount, 1);
  36   if (info.bmiHeader.biBitCount != 1)
  37     return data.Pass();
  38
  39   // When getting pixel data palette is appended to memory pointed by
  40   // BITMAPINFO passed so allocate additional memory to store additional data.
  41   scoped_ptr<BITMAPINFO> header(
  42       reinterpret_cast<BITMAPINFO*>(new char[KHeaderAndPalette]));
  43   memcpy(header.get(), &(info.bmiHeader), sizeof(info.bmiHeader));
  44
  45   data.reset(new uint32_t[info.bmiHeader.biSizeImage / sizeof(uint32_t)]);
  46
  47   int result = GetDIBits(hdc,
  48                          handle,
  49                          0,
  50                          info.bmiHeader.biHeight,
  51                          data.get(),
  52                          header.get(),
  53                          DIB_RGB_COLORS);
  54
  55   if (result == 0)
  56     data.reset();
  57
  58   return data.Pass();
  59 }
  60
  61 // Checks if the specifed row is transparent in provided bitmap.
  62 bool IsRowTransparent(const PixelData& data,
  63                       const uint32_t row_size,
  64                       const uint32_t last_byte_mask,
  65                       const uint32_t y) {
  66   // Set the padding bits to 1 to make mask matching easier.
  67   *(data.get() + (y + 1) * row_size - 1) |= last_byte_mask;
  68   for (uint32_t i = y * row_size; i < (y + 1) * row_size; ++i) {
  69     if (*(data.get() + i) != kTransparentMask)
  70       return false;
  71   }
  72   return true;
  73 }
  74
  75 // Gets the vertical offset between specified cursor's hotpoint and it's bottom.
  76 //
  77 // Gets the cursor image data and extract cursor's visible height.
  78 // Based on that get's what should be the vertical offset between cursor's
  79 // hot point and the tooltip.
  80 int CalculateCursorHeight(HCURSOR cursor_handle) {
  81   base::win::ScopedGetDC hdc(NULL);
  82
  83   ICONINFO icon = {0};
  84   GetIconInfo(cursor_handle, &icon);
  85
  86   BITMAPINFO bitmap_info = {0};
  87   bitmap_info.bmiHeader.biSize = sizeof(bitmap_info.bmiHeader);
  88   if (GetDIBits(hdc, icon.hbmMask, 0, 0, NULL, &bitmap_info, DIB_RGB_COLORS) ==
  89       0)
  90     return kDefaultHeight;
  91
  92   // Rows are padded to full DWORDs. OR with this mask will set them to 1
  93   // to simplify matching with |transparent_mask|.
  94   uint32_t last_byte_mask = 0xFFFFFFFF;
  95   const unsigned char bits_to_shift = sizeof(last_byte_mask) * 8 -
  96       (bitmap_info.bmiHeader.biWidth % kBitsPeruint32);
  97   if (bits_to_shift != kBitsPeruint32)
  98     last_byte_mask = (last_byte_mask << bits_to_shift);
  99   else
 100     last_byte_mask = 0;
 101
 102   const uint32_t row_size =
 103       (bitmap_info.bmiHeader.biWidth + kBitsPeruint32 - 1) / kBitsPeruint32;
 104   PixelData data(GetBitmapData(icon.hbmMask, bitmap_info, hdc));
 105   if (data == NULL)
 106     return kDefaultHeight;
 107
 108   const int cursor_height = GetSystemMetrics(SM_CYCURSOR);
 109   // Crash data seems to indicate cursor_height may be bigger than the bitmap.
 110   int i = std::max(0, static_cast<int>(bitmap_info.bmiHeader.biHeight) -
 111                    cursor_height);
 112   for (; i < bitmap_info.bmiHeader.biHeight; ++i) {
 113     if (!IsRowTransparent(data, row_size, last_byte_mask, i)) {
 114       i--;
 115       break;
 116     }
 117   }
 118   return bitmap_info.bmiHeader.biHeight - i - icon.yHotspot;
 119 }
 120
 121 }  // namespace
 122
 123 namespace views {
 124 namespace corewm {
 125
 126 int GetCurrentCursorVisibleHeight() {
 127   CURSORINFO cursor = {0};
 128   cursor.cbSize = sizeof(cursor);
 129   GetCursorInfo(&cursor);
 130
 131   if (cached_heights == NULL)
 132     cached_heights = new HeightStorage;
 133
 134   HeightStorage::const_iterator cached_height =
 135       cached_heights->find(cursor.hCursor);
 136   if (cached_height != cached_heights->end())
 137     return cached_height->second;
 138
 139   const int height = CalculateCursorHeight(cursor.hCursor);
 140   (*cached_heights)[cursor.hCursor] = height;
 141
 142   return height;
 143 }
 144
 145 }  // namespace corewm
 146 }  // namespace views