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      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/files/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, cursor_offset, data_object);
     96 }
     97 
     98 void SetDragImageOnDataObject(const gfx::Canvas& canvas,
     99                               const gfx::Vector2d& cursor_offset,
    100                               ui::OSExchangeData* data_object) {
    101   gfx::ImageSkia image = gfx::ImageSkia(canvas.ExtractImageRep());
    102   SetDragImageOnDataObject(image, cursor_offset, data_object);
    103 }
    104 
    105 }  // namespace drag_utils
    106