ui/base/dragdrop/drag_utils.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/base/dragdrop/drag_utils.h"
   6
   7 #include "base/file_util.h"
   8 #include "base/logging.h"
   9 #include "base/strings/utf_string_conversions.h"
  10 #include "ui/base/dragdrop/os_exchange_data.h"
  11 #include "ui/gfx/canvas.h"
  12 #include "ui/gfx/font_list.h"
  13 #include "ui/gfx/geometry/point.h"
  14 #include "ui/gfx/geometry/rect.h"
  15 #include "ui/gfx/geometry/size.h"
  16 #include "ui/gfx/image/canvas_image_source.h"
  17 #include "url/gurl.h"
  18
  19 namespace drag_utils {
  20
  21 namespace {
  22
  23 // Maximum width of the link drag image in pixels.
  24 static const int kLinkDragImageVPadding = 3;
  25
  26 // File dragging pixel measurements
  27 static const int kFileDragImageMaxWidth = 200;
  28 static const SkColor kFileDragImageTextColor = SK_ColorBLACK;
  29
  30 class FileDragImageSource : public gfx::CanvasImageSource {
  31  public:
  32   FileDragImageSource(const base::FilePath& file_name,
  33                       const gfx::ImageSkia& icon)
  34       : CanvasImageSource(CalculateSize(icon), false),
  35         file_name_(file_name),
  36         icon_(icon) {
  37   }
  38
  39   virtual ~FileDragImageSource() {
  40   }
  41
  42   // Overridden from gfx::CanvasImageSource.
  43   virtual void Draw(gfx::Canvas* canvas) OVERRIDE {
  44     if (!icon_.isNull()) {
  45       // Paint the icon.
  46       canvas->DrawImageInt(icon_, (size().width() - icon_.width()) / 2, 0);
  47     }
  48
  49     base::string16 name = file_name_.BaseName().LossyDisplayName();
  50     const int flags = gfx::Canvas::TEXT_ALIGN_CENTER;
  51     const gfx::FontList font_list;
  52 #if defined(OS_WIN)
  53     // Paint the file name. We inset it one pixel to allow room for the halo.
  54     const gfx::Rect rect(1, icon_.height() + kLinkDragImageVPadding + 1,
  55                          size().width() - 2, font_list.GetHeight());
  56     canvas->DrawStringRectWithHalo(name, font_list, kFileDragImageTextColor,
  57                                    SK_ColorWHITE, rect, flags);
  58 #else
  59     // NO_SUBPIXEL_RENDERING is required when drawing to a non-opaque canvas.
  60     const gfx::Rect rect(0, icon_.height() + kLinkDragImageVPadding,
  61                          size().width(), font_list.GetHeight());
  62     canvas->DrawStringRectWithFlags(name, font_list, kFileDragImageTextColor,
  63                                     rect,
  64                                     flags | gfx::Canvas::NO_SUBPIXEL_RENDERING);
  65 #endif
  66   }
  67
  68  private:
  69   gfx::Size CalculateSize(const gfx::ImageSkia& icon) const {
  70     const int width = kFileDragImageMaxWidth;
  71     // Add +2 here to allow room for the halo.
  72     const int height = gfx::FontList().GetHeight() + icon.height() +
  73                        kLinkDragImageVPadding + 2;
  74     return gfx::Size(width, height);
  75   }
  76
  77   const base::FilePath file_name_;
  78   const gfx::ImageSkia icon_;
  79
  80   DISALLOW_COPY_AND_ASSIGN(FileDragImageSource);
  81 };
  82
  83 }  // namespace
  84
  85 void CreateDragImageForFile(const base::FilePath& file_name,
  86                             const gfx::ImageSkia& icon,
  87                             ui::OSExchangeData* data_object) {
  88   DCHECK(data_object);
  89   gfx::CanvasImageSource* source = new FileDragImageSource(file_name, icon);
  90   gfx::Size size = source->size();
  91   // ImageSkia takes ownership of |source|.
  92   gfx::ImageSkia image = gfx::ImageSkia(source, size);
  93
  94   gfx::Vector2d cursor_offset(size.width() / 2, kLinkDragImageVPadding);
  95   SetDragImageOnDataObject(image, size, cursor_offset, data_object);
  96 }
  97
  98 void SetDragImageOnDataObject(const gfx::Canvas& canvas,
  99                               const gfx::Size& size,
 100                               const gfx::Vector2d& cursor_offset,
 101                               ui::OSExchangeData* data_object) {
 102   gfx::ImageSkia image = gfx::ImageSkia(canvas.ExtractImageRep());
 103   SetDragImageOnDataObject(image, size, cursor_offset, data_object);
 104 }
 105
 106 }  // namespace drag_utils