ui/gfx/gdi_util.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 "ui/gfx/gdi_util.h"
   6
   7 #include "base/logging.h"
   8 #include "base/memory/scoped_ptr.h"
   9
  10 namespace gfx {
  11
  12 void CreateBitmapHeader(int width, int height, BITMAPINFOHEADER* hdr) {
  13   CreateBitmapHeaderWithColorDepth(width, height, 32, hdr);
  14 }
  15
  16 void CreateBitmapHeaderWithColorDepth(int width, int height, int color_depth,
  17                                       BITMAPINFOHEADER* hdr) {
  18   // These values are shared with gfx::PlatformDevice
  19   hdr->biSize = sizeof(BITMAPINFOHEADER);
  20   hdr->biWidth = width;
  21   hdr->biHeight = -height;  // minus means top-down bitmap
  22   hdr->biPlanes = 1;
  23   hdr->biBitCount = color_depth;
  24   hdr->biCompression = BI_RGB;  // no compression
  25   hdr->biSizeImage = 0;
  26   hdr->biXPelsPerMeter = 1;
  27   hdr->biYPelsPerMeter = 1;
  28   hdr->biClrUsed = 0;
  29   hdr->biClrImportant = 0;
  30 }
  31
  32 void CreateBitmapV4Header(int width, int height, BITMAPV4HEADER* hdr) {
  33   // Because bmp v4 header is just an extension, we just create a v3 header and
  34   // copy the bits over to the v4 header.
  35   BITMAPINFOHEADER header_v3;
  36   CreateBitmapHeader(width, height, &header_v3);
  37   memset(hdr, 0, sizeof(BITMAPV4HEADER));
  38   memcpy(hdr, &header_v3, sizeof(BITMAPINFOHEADER));
  39
  40   // Correct the size of the header and fill in the mask values.
  41   hdr->bV4Size = sizeof(BITMAPV4HEADER);
  42   hdr->bV4RedMask   = 0x00ff0000;
  43   hdr->bV4GreenMask = 0x0000ff00;
  44   hdr->bV4BlueMask  = 0x000000ff;
  45   hdr->bV4AlphaMask = 0xff000000;
  46 }
  47
  48 // Creates a monochrome bitmap header.
  49 void CreateMonochromeBitmapHeader(int width,
  50                                   int height,
  51                                   BITMAPINFOHEADER* hdr) {
  52   hdr->biSize = sizeof(BITMAPINFOHEADER);
  53   hdr->biWidth = width;
  54   hdr->biHeight = -height;
  55   hdr->biPlanes = 1;
  56   hdr->biBitCount = 1;
  57   hdr->biCompression = BI_RGB;
  58   hdr->biSizeImage = 0;
  59   hdr->biXPelsPerMeter = 1;
  60   hdr->biYPelsPerMeter = 1;
  61   hdr->biClrUsed = 0;
  62   hdr->biClrImportant = 0;
  63 }
  64
  65 void SubtractRectanglesFromRegion(HRGN hrgn,
  66                                   const std::vector<gfx::Rect>& cutouts) {
  67   if (cutouts.size()) {
  68     HRGN cutout = ::CreateRectRgn(0, 0, 0, 0);
  69     for (size_t i = 0; i < cutouts.size(); i++) {
  70       ::SetRectRgn(cutout,
  71                    cutouts[i].x(),
  72                    cutouts[i].y(),
  73                    cutouts[i].right(),
  74                    cutouts[i].bottom());
  75       ::CombineRgn(hrgn, hrgn, cutout, RGN_DIFF);
  76     }
  77     ::DeleteObject(cutout);
  78   }
  79 }
  80
  81 HRGN ConvertPathToHRGN(const gfx::Path& path) {
  82 #if defined(USE_AURA)
  83   int point_count = path.getPoints(NULL, 0);
  84   scoped_ptr<SkPoint[]> points(new SkPoint[point_count]);
  85   path.getPoints(points.get(), point_count);
  86   scoped_ptr<POINT[]> windows_points(new POINT[point_count]);
  87   for (int i = 0; i < point_count; ++i) {
  88     windows_points[i].x = SkScalarRound(points[i].fX);
  89     windows_points[i].y = SkScalarRound(points[i].fY);
  90   }
  91
  92   return ::CreatePolygonRgn(windows_points.get(), point_count, ALTERNATE);
  93 #elif defined(OS_WIN)
  94   return path.CreateNativeRegion();
  95 #endif
  96 }
  97
  98
  99 double CalculatePageScale(HDC dc, int page_width, int page_height) {
 100   int dc_width = GetDeviceCaps(dc, HORZRES);
 101   int dc_height = GetDeviceCaps(dc, VERTRES);
 102
 103   // If page fits DC - no scaling needed.
 104   if (dc_width >= page_width && dc_height >= page_height)
 105     return 1.0;
 106
 107   double x_factor =
 108       static_cast<double>(dc_width) / static_cast<double>(page_width);
 109   double y_factor =
 110       static_cast<double>(dc_height) / static_cast<double>(page_height);
 111   return std::min(x_factor, y_factor);
 112 }
 113
 114 // Apply scaling to the DC.
 115 bool ScaleDC(HDC dc, double scale_factor) {
 116   SetGraphicsMode(dc, GM_ADVANCED);
 117   XFORM xform = {0};
 118   xform.eM11 = xform.eM22 = scale_factor;
 119   return !!ModifyWorldTransform(dc, &xform, MWT_LEFTMULTIPLY);
 120 }
 121
 122 void StretchDIBits(HDC hdc, int dest_x, int dest_y, int dest_w, int dest_h,
 123                    int src_x, int src_y, int src_w, int src_h, void* pixels,
 124                    const BITMAPINFO* bitmap_info) {
 125   // When blitting a rectangle that touches the bottom, left corner of the
 126   // bitmap, StretchDIBits looks at it top-down!  For more details, see
 127   // http://wiki.allegro.cc/index.php?title=StretchDIBits.
 128   int rv;
 129   int bitmap_h = -bitmap_info->bmiHeader.biHeight;
 130   int bottom_up_src_y = bitmap_h - src_y - src_h;
 131   if (bottom_up_src_y == 0 && src_x == 0 && src_h != bitmap_h) {
 132     rv = ::StretchDIBits(hdc,
 133                          dest_x, dest_h + dest_y - 1, dest_w, -dest_h,
 134                          src_x, bitmap_h - src_y + 1, src_w, -src_h,
 135                          pixels, bitmap_info, DIB_RGB_COLORS, SRCCOPY);
 136   } else {
 137     rv = ::StretchDIBits(hdc,
 138                          dest_x, dest_y, dest_w, dest_h,
 139                          src_x, bottom_up_src_y, src_w, src_h,
 140                          pixels, bitmap_info, DIB_RGB_COLORS, SRCCOPY);
 141   }
 142   DCHECK(rv != GDI_ERROR);
 143 }
 144
 145 }  // namespace gfx