device/hid/hid_report_descriptor.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 "device/hid/hid_report_descriptor.h"
   6
   7 #include "base/stl_util.h"
   8
   9 namespace device {
  10
  11 HidReportDescriptor::HidReportDescriptor(const uint8_t* bytes, size_t size) {
  12   size_t header_index = 0;
  13   HidReportDescriptorItem* item = NULL;
  14   while (header_index < size) {
  15     item = new HidReportDescriptorItem(&bytes[header_index], item);
  16     items_.push_back(linked_ptr<HidReportDescriptorItem>(item));
  17     header_index += item->GetSize();
  18   }
  19 }
  20
  21 HidReportDescriptor::~HidReportDescriptor() {}
  22
  23 void HidReportDescriptor::GetTopLevelCollections(
  24     std::vector<HidUsageAndPage>* topLevelCollections) {
  25   DCHECK(topLevelCollections);
  26   STLClearObject(topLevelCollections);
  27
  28   for (std::vector<linked_ptr<HidReportDescriptorItem> >::const_iterator
  29            items_iter = items().begin();
  30        items_iter != items().end();
  31        ++items_iter) {
  32     linked_ptr<HidReportDescriptorItem> item = *items_iter;
  33
  34     bool isTopLevelCollection =
  35         item->tag() == HidReportDescriptorItem::kTagCollection &&
  36         item->parent() == NULL;
  37
  38     if (isTopLevelCollection) {
  39       uint16_t collection_usage = 0;
  40       HidUsageAndPage::Page collection_usage_page =
  41           HidUsageAndPage::kPageUndefined;
  42
  43       HidReportDescriptorItem* usage = item->previous();
  44       if (usage && usage->tag() == HidReportDescriptorItem::kTagUsage) {
  45         collection_usage = usage->GetShortData();
  46       }
  47
  48       HidReportDescriptorItem* usage_page = usage->previous();
  49       if (usage_page &&
  50           usage_page->tag() == HidReportDescriptorItem::kTagUsagePage) {
  51         collection_usage_page =
  52             (HidUsageAndPage::Page)usage_page->GetShortData();
  53       }
  54
  55       topLevelCollections->push_back(
  56           HidUsageAndPage(collection_usage, collection_usage_page));
  57     }
  58   }
  59 }
  60
  61 }  // namespace device