platform_view_android_delegate.cc

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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#include "flutter/shell/platform/android/platform_view_android_delegate/platform_view_android_delegate.h"
 
#include <utility>
 
namespace flutter {
namespace {
void putStringAttributesIntoBuffer(
    const StringAttributes& attributes,
    int32_t* buffer,
    size_t* position,
    std::vector<std::vector<uint8_t>>& string_attribute_args) {
  if (attributes.empty()) {
    buffer[(*position)++] = PlatformViewAndroidDelegate::kEmptyStringIndex;
    return;
  }
  buffer[(*position)++] = attributes.size();
  for (const auto& attribute : attributes) {
    buffer[(*position)++] = attribute->start;
    buffer[(*position)++] = attribute->end;
    buffer[(*position)++] = static_cast<int32_t>(attribute->type);
    switch (attribute->type) {
      case StringAttributeType::kSpellOut:
        buffer[(*position)++] = PlatformViewAndroidDelegate::kEmptyStringIndex;
        break;
      case StringAttributeType::kLocale:
        buffer[(*position)++] = string_attribute_args.size();
        std::shared_ptr<LocaleStringAttribute> locale_attribute =
            std::static_pointer_cast<LocaleStringAttribute>(attribute);
        string_attribute_args.push_back(
            {locale_attribute->locale.begin(), locale_attribute->locale.end()});
        break;
    }
  }
}
 
void putStringIntoBuffer(const std::string& string,
                         int32_t* buffer,
                         size_t* position,
                         std::vector<std::string>& strings) {
  if (string.empty()) {
    buffer[(*position)++] = PlatformViewAndroidDelegate::kEmptyStringIndex;
  } else {
    buffer[(*position)++] = strings.size();
    strings.push_back(string);
  }
}
 
int64_t flagsToInt64(flutter::SemanticsFlags flags) {
  int64_t result = 0;
  if (flags.isChecked != flutter::SemanticsCheckState::kNone) {
    result |= (INT64_C(1) << 0);
  }
  if (flags.isChecked == flutter::SemanticsCheckState::kTrue) {
    result |= (INT64_C(1) << 1);
  }
  if (flags.isSelected == flutter::SemanticsTristate::kTrue) {
    result |= (INT64_C(1) << 2);
  }
  if (flags.isButton) {
    result |= (INT64_C(1) << 3);
  }
  if (flags.isTextField) {
    result |= (INT64_C(1) << 4);
  }
  if (flags.isFocused == flutter::SemanticsTristate::kTrue) {
    result |= (INT64_C(1) << 5);
  }
  if (flags.isEnabled != flutter::SemanticsTristate::kNone) {
    result |= (INT64_C(1) << 6);
  }
  if (flags.isEnabled == flutter::SemanticsTristate::kTrue) {
    result |= (INT64_C(1) << 7);
  }
  if (flags.isInMutuallyExclusiveGroup) {
    result |= (INT64_C(1) << 8);
  }
  if (flags.isHeader) {
    result |= (INT64_C(1) << 9);
  }
  if (flags.isObscured) {
    result |= (INT64_C(1) << 10);
  }
  if (flags.scopesRoute) {
    result |= (INT64_C(1) << 11);
  }
  if (flags.namesRoute) {
    result |= (INT64_C(1) << 12);
  }
  if (flags.isHidden) {
    result |= (INT64_C(1) << 13);
  }
  if (flags.isImage) {
    result |= (INT64_C(1) << 14);
  }
  if (flags.isLiveRegion) {
    result |= (INT64_C(1) << 15);
  }
  if (flags.isToggled != flutter::SemanticsTristate::kNone) {
    result |= (INT64_C(1) << 16);
  }
  if (flags.isToggled == flutter::SemanticsTristate::kTrue) {
    result |= (INT64_C(1) << 17);
  }
  if (flags.hasImplicitScrolling) {
    result |= (INT64_C(1) << 18);
  }
  if (flags.isMultiline) {
    result |= (INT64_C(1) << 19);
  }
  if (flags.isReadOnly) {
    result |= (INT64_C(1) << 20);
  }
  if (flags.isFocused != flutter::SemanticsTristate::kNone) {
    result |= (INT64_C(1) << 21);
  }
  if (flags.isLink) {
    result |= (INT64_C(1) << 22);
  }
  if (flags.isSlider) {
    result |= (INT64_C(1) << 23);
  }
  if (flags.isKeyboardKey) {
    result |= (INT64_C(1) << 24);
  }
  if (flags.isChecked == flutter::SemanticsCheckState::kMixed) {
    result |= (INT64_C(1) << 25);
  }
  if (flags.isExpanded != flutter::SemanticsTristate::kNone) {
    result |= (INT64_C(1) << 26);
  }
  if (flags.isExpanded == flutter::SemanticsTristate::kTrue) {
    result |= (INT64_C(1) << 27);
  }
  if (flags.isSelected != flutter::SemanticsTristate::kNone) {
    result |= (INT64_C(1) << 28);
  }
  if (flags.isRequired != flutter::SemanticsTristate::kNone) {
    result |= (INT64_C(1) << 29);
  }
  if (flags.isRequired == flutter::SemanticsTristate::kTrue) {
    result |= (INT64_C(1) << 30);
  }
  if (flags.isAccessibilityFocusBlocked) {
    result |= (INT64_C(1) << 31);
  }
  return result;
}
}  // namespace
 
PlatformViewAndroidDelegate::PlatformViewAndroidDelegate(
    std::shared_ptr<PlatformViewAndroidJNI> jni_facade)
    : jni_facade_(std::move(jni_facade)) {};
 
void PlatformViewAndroidDelegate::UpdateSemantics(
    const flutter::SemanticsNodeUpdates& update,
    const flutter::CustomAccessibilityActionUpdates& actions) {
  {
    size_t num_bytes = 0;
    for (const auto& value : update) {
      num_bytes += kBytesPerNode;
      num_bytes +=
          value.second.childrenInTraversalOrder.size() * kBytesPerChild;
      num_bytes += value.second.childrenInHitTestOrder.size() * kBytesPerChild;
      num_bytes += value.second.customAccessibilityActions.size() *
                   kBytesPerCustomAction;
      num_bytes +=
          value.second.labelAttributes.size() * kBytesPerStringAttribute;
      num_bytes +=
          value.second.valueAttributes.size() * kBytesPerStringAttribute;
      num_bytes += value.second.increasedValueAttributes.size() *
                   kBytesPerStringAttribute;
      num_bytes += value.second.decreasedValueAttributes.size() *
                   kBytesPerStringAttribute;
      num_bytes +=
          value.second.hintAttributes.size() * kBytesPerStringAttribute;
    }
    // The encoding defined here is used in:
    //
    //  * AccessibilityBridge.java
    //  * AccessibilityBridgeTest.java
    //  * accessibility_bridge.mm
    //
    // If any of the encoding structure or length is changed, those locations
    // must be updated (at a minimum).
    std::vector<uint8_t> buffer(num_bytes);
    int32_t* buffer_int32 = reinterpret_cast<int32_t*>(&buffer[0]);
    float* buffer_float32 = reinterpret_cast<float*>(&buffer[0]);
 
    std::vector<std::string> strings;
    std::vector<std::vector<uint8_t>> string_attribute_args;
    size_t position = 0;
    for (const auto& value : update) {
      // If you edit this code, make sure you update kBytesPerNode
      // and/or kBytesPerChild above to match the number of values you are
      // sending.
      const flutter::SemanticsNode& node = value.second;
      buffer_int32[position++] = node.id;
      int64_t flags = flagsToInt64(node.flags);
      std::memcpy(&buffer_int32[position], &flags, 8);
      position += 2;
      buffer_int32[position++] = node.actions;
      buffer_int32[position++] = node.maxValueLength;
      buffer_int32[position++] = node.currentValueLength;
      buffer_int32[position++] = node.textSelectionBase;
      buffer_int32[position++] = node.textSelectionExtent;
      buffer_int32[position++] = node.platformViewId;
      buffer_int32[position++] = node.scrollChildren;
      buffer_int32[position++] = node.scrollIndex;
      buffer_int32[position++] = node.traversalParent;
      buffer_float32[position++] = static_cast<float>(node.scrollPosition);
      buffer_float32[position++] = static_cast<float>(node.scrollExtentMax);
      buffer_float32[position++] = static_cast<float>(node.scrollExtentMin);
 
      putStringIntoBuffer(node.identifier, buffer_int32, &position, strings);
 
      putStringIntoBuffer(node.label, buffer_int32, &position, strings);
      putStringAttributesIntoBuffer(node.labelAttributes, buffer_int32,
                                    &position, string_attribute_args);
 
      putStringIntoBuffer(node.value, buffer_int32, &position, strings);
      putStringAttributesIntoBuffer(node.valueAttributes, buffer_int32,
                                    &position, string_attribute_args);
 
      putStringIntoBuffer(node.increasedValue, buffer_int32, &position,
                          strings);
      putStringAttributesIntoBuffer(node.increasedValueAttributes, buffer_int32,
                                    &position, string_attribute_args);
 
      putStringIntoBuffer(node.decreasedValue, buffer_int32, &position,
                          strings);
      putStringAttributesIntoBuffer(node.decreasedValueAttributes, buffer_int32,
                                    &position, string_attribute_args);
 
      putStringIntoBuffer(node.hint, buffer_int32, &position, strings);
      putStringAttributesIntoBuffer(node.hintAttributes, buffer_int32,
                                    &position, string_attribute_args);
 
      putStringIntoBuffer(node.tooltip, buffer_int32, &position, strings);
      putStringIntoBuffer(node.linkUrl, buffer_int32, &position, strings);
      putStringIntoBuffer(node.locale, buffer_int32, &position, strings);
 
      buffer_int32[position++] = node.headingLevel;
      buffer_int32[position++] = node.textDirection;
      buffer_float32[position++] = node.rect.left();
      buffer_float32[position++] = node.rect.top();
      buffer_float32[position++] = node.rect.right();
      buffer_float32[position++] = node.rect.bottom();
      node.transform.getColMajor(&buffer_float32[position]);
      position += 16;
      node.hitTestTransform.getColMajor(&buffer_float32[position]);
      position += 16;
      buffer_int32[position++] = node.childrenInTraversalOrder.size();
      for (int32_t child : node.childrenInTraversalOrder) {
        buffer_int32[position++] = child;
      }
 
      buffer_int32[position++] = node.childrenInHitTestOrder.size();
      for (int32_t child : node.childrenInHitTestOrder) {
        buffer_int32[position++] = child;
      }
 
      buffer_int32[position++] = node.customAccessibilityActions.size();
      for (int32_t child : node.customAccessibilityActions) {
        buffer_int32[position++] = child;
      }
    }
 
    // custom accessibility actions.
    size_t num_action_bytes = actions.size() * kBytesPerAction;
    std::vector<uint8_t> actions_buffer(num_action_bytes);
    int32_t* actions_buffer_int32 =
        reinterpret_cast<int32_t*>(&actions_buffer[0]);
 
    std::vector<std::string> action_strings;
    size_t actions_position = 0;
    for (const auto& value : actions) {
      // If you edit this code, make sure you update kBytesPerAction
      // to match the number of values you are
      // sending.
      const flutter::CustomAccessibilityAction& action = value.second;
      actions_buffer_int32[actions_position++] = action.id;
      actions_buffer_int32[actions_position++] = action.overrideId;
      putStringIntoBuffer(action.label, actions_buffer_int32, &actions_position,
                          action_strings);
      putStringIntoBuffer(action.hint, actions_buffer_int32, &actions_position,
                          action_strings);
    }
 
    // Calling NewDirectByteBuffer in API level 22 and below with a size of zero
    // will cause a JNI crash.
    if (!actions_buffer.empty()) {
      jni_facade_->FlutterViewUpdateCustomAccessibilityActions(actions_buffer,
                                                               action_strings);
    }
 
    if (!buffer.empty()) {
      jni_facade_->FlutterViewUpdateSemantics(buffer, strings,
                                              string_attribute_args);
    }
  }
}
 
}  // namespace flutter