eglChooseConfig function

List<Pointer<Void>> eglChooseConfig(Pointer<Void> display, { Map<EglConfigAttribute, int>? attributes, int maxConfigs = 1, })

https://www.khronos.org/registry/EGL/sdk/docs/man/html/eglChooseConfig.xhtml

Implementation

List<Pointer<Void>> eglChooseConfig(
  Pointer<Void> display, {
  Map<EglConfigAttribute, int>? attributes,
  int maxConfigs = 1,
}) {
  final attributeCount = attributes == null ? 1 : attributes.length * 2 + 1;
  final attributeList = allocate<Int32>(count: attributeCount);

  if (attributes != null) {
    final attributeEntries = attributes.entries.toList(growable: false);

    for (var i = 0; i < attributeEntries.length; ++i) {
      attributeList[i * 2] = attributeEntries[i].key.toIntValue();
      attributeList[i * 2 + 1] = attributeEntries[i].value;
    }
  }

  // The list must be terminated with EGL_NONE.
  attributeList[attributeCount - 1] = EglValue.none.toIntValue();

  final configs = allocate<IntPtr>(count: maxConfigs);
  final numConfigs = allocate<Int32>();
  final nativeCallSucceeded = _libEGL.eglChooseConfig(
        display,
        attributeList,
        configs.cast<Pointer<Void>>(),
        maxConfigs,
        numConfigs,
      ) ==
      1;
  List<Pointer<Void>> result = <Pointer<Void>>[];

  if (nativeCallSucceeded) {
    for (var i = 0; i < numConfigs.value; ++i) {
      result.add(Pointer.fromAddress(configs[i]));
    }
  }

  free(attributeList);
  free(configs);
  free(numConfigs);

  if (!nativeCallSucceeded) {
    throw EglException(
        'Failed to choose config for display [$display], attributes $attributes, max configs $maxConfigs.');
  }

  return result;
}