cc/resources/resource.h

   1 // Copyright 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 #ifndef CC_RESOURCES_RESOURCE_H_
   6 #define CC_RESOURCES_RESOURCE_H_
   7
   8 #include "base/numerics/safe_math.h"
   9 #include "cc/base/cc_export.h"
  10 #include "cc/resources/resource_provider.h"
  11 #include "ui/gfx/geometry/size.h"
  12
  13 namespace cc {
  14
  15 class CC_EXPORT Resource {
  16  public:
  17   Resource() : id_(0), format_(RGBA_8888) {}
  18   Resource(unsigned id, const gfx::Size& size, ResourceFormat format)
  19       : id_(id),
  20         size_(size),
  21         format_(format) {}
  22
  23   ResourceId id() const { return id_; }
  24   gfx::Size size() const { return size_; }
  25   ResourceFormat format() const { return format_; }
  26
  27   // Return true if the call to UncheckedMemorySizeBytes would return a value
  28   // that fits in a size_t.
  29   static bool VerifySizeInBytes(const gfx::Size& size, ResourceFormat format) {
  30     base::CheckedNumeric<size_t> checked_value = BitsPerPixel(format);
  31     checked_value *= size.width();
  32     checked_value *= size.height();
  33     if (!checked_value.IsValid())
  34       return false;
  35     size_t value = checked_value.ValueOrDie();
  36     if ((value % 8) != 0)
  37       return false;
  38     return true;
  39   }
  40
  41   static size_t CheckedMemorySizeBytes(const gfx::Size& size,
  42                                        ResourceFormat format) {
  43     DCHECK(VerifySizeInBytes(size, format));
  44     base::CheckedNumeric<size_t> checked_value = BitsPerPixel(format);
  45     checked_value *= size.width();
  46     checked_value *= size.height();
  47     checked_value /= 8;
  48     return checked_value.ValueOrDie();
  49   }
  50
  51   inline static size_t UncheckedMemorySizeBytes(const gfx::Size& size,
  52                                                 ResourceFormat format) {
  53     DCHECK(VerifySizeInBytes(size, format));
  54     return static_cast<size_t>(BitsPerPixel(format)) * size.width() *
  55            size.height() / 8;
  56   }
  57
  58  protected:
  59   void set_id(ResourceId id) { id_ = id; }
  60   void set_dimensions(const gfx::Size& size, ResourceFormat format) {
  61     size_ = size;
  62     format_ = format;
  63   }
  64
  65  private:
  66   ResourceId id_;
  67   gfx::Size size_;
  68   ResourceFormat format_;
  69
  70   DISALLOW_COPY_AND_ASSIGN(Resource);
  71 };
  72
  73 }  // namespace cc
  74
  75 #endif  // CC_RESOURCES_RESOURCE_H_