[C#/WINUI3/.NET8] VisualTreeHelper 클래스 : GetChildrenCount/GetChild 정적 메소드를 사용해 DependencyObject 객체에서 특정 타입의 첫번째 자손 객체 구하기

■ VisualTreeHelper 클래스의 GetChildrenCount/GetChild 정적 메소드를 사용해 DependencyObject 객체에서 특정 타입의 첫번째 자손 객체를 구하는 방법을 보여준다.

※ 자식과 손자 객체까지만 탐색한다.

▶ 예제 코드 (C#)


using System.Linq;
using System.Collections.Generic;

using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Media;

#region 첫번째 자손 객체 구하기 - GetFirstDescendantObjectOfType<TDescendant>(sourceObject)

/// <summary>
/// 첫번째 자손 객체 구하기
/// </summary>
/// <typeparam name="TDescendant">자손 타입</typeparam>
/// <param name="sourceObject">소스 객체</param>
/// <returns>자손 객체</returns>
public TDescendant GetFirstDescendantObjectOfType<TDescendant>(DependencyObject sourceObject) where TDescendant : DependencyObject
{
    IEnumerable<DependencyObject> childObjectEnumerable = sourceObject.GetDescendantObjectEnumerableOfType<TDescendant>();

    return childObjectEnumerable.FirstOrDefault();
}

#endregion
#region 자손 객체 열거 가능형 구하기 - GetDescendantObjectEnumerableOfType<TDescendant>(sourceObject)

/// <summary>
/// 자손 객체 열거 가능형 구하기
/// </summary>
/// <typeparam name="TDescendant">자손 타입</typeparam>
/// <param name="sourceObject">소스 객체</param>
/// <returns>자손 객체 열거 가능형</returns>
private IEnumerable<TDescendant> GetDescendantObjectEnumerableOfType<TDescendant>(DependencyObject sourceObject) where TDescendant : DependencyObject
{
    IEnumerable<DependencyObject> childObjectEnumerable = GetDescendantObjectEnumerable(sourceObject);

    return childObjectEnumerable.OfType<TDescendant>();
}

#endregion
#region 자손 객체 열거 가능형 구하기 - GetDescendantObjectEnumerable(sourceObject)

/// <summary>
/// 자손 객체 열거 가능형 구하기
/// </summary>
/// <param name="sourceObject">소스 객체</param>
/// <returns>자손 객체 열거 가능형</returns>
private IEnumerable<DependencyObject> GetDescendantObjectEnumerable(DependencyObject sourceObject)
{
    Queue<DependencyObject> queue = new Queue<DependencyObject>();

    int count1 = VisualTreeHelper.GetChildrenCount(sourceObject);

    for(int i = 0; i < count1; i++)
    {
        DependencyObject childObject = VisualTreeHelper.GetChild(sourceObject, i);

        yield return childObject;

        queue.Enqueue(childObject);
    }

    while(queue.Count > 0)
    {
        DependencyObject parentObject = queue.Dequeue();

        int count2 = VisualTreeHelper.GetChildrenCount(parentObject);

        for(int i = 0; i < count2; i++)
        {
            DependencyObject childDependencyObject = VisualTreeHelper.GetChild(parentObject, i);

            yield return childDependencyObject;

            queue.Enqueue(childDependencyObject);
        }
    }
}

#endregion

using System.Linq;

using System.Collections.Generic;

using Microsoft.UI.Xaml;

using Microsoft.UI.Xaml.Media;

#region 첫번째 자손 객체 구하기 - GetFirstDescendantObjectOfType<TDescendant>(sourceObject)

/// <summary>

/// 첫번째 자손 객체 구하기

/// </summary>

/// <typeparam name="TDescendant">자손 타입</typeparam>

/// <param name="sourceObject">소스 객체</param>

/// <returns>자손 객체</returns>

public TDescendant GetFirstDescendantObjectOfType<TDescendant>(DependencyObject sourceObject) where TDescendant : DependencyObject

{

IEnumerable<DependencyObject> childObjectEnumerable = sourceObject.GetDescendantObjectEnumerableOfType<TDescendant>();

return childObjectEnumerable.FirstOrDefault();

}

#endregion

#region 자손 객체 열거 가능형 구하기 - GetDescendantObjectEnumerableOfType<TDescendant>(sourceObject)

/// <summary>

/// 자손 객체 열거 가능형 구하기

/// </summary>

/// <typeparam name="TDescendant">자손 타입</typeparam>

/// <param name="sourceObject">소스 객체</param>

/// <returns>자손 객체 열거 가능형</returns>

private IEnumerable<TDescendant> GetDescendantObjectEnumerableOfType<TDescendant>(DependencyObject sourceObject) where TDescendant : DependencyObject

{

IEnumerable<DependencyObject> childObjectEnumerable = GetDescendantObjectEnumerable(sourceObject);

return childObjectEnumerable.OfType<TDescendant>();

}

#endregion

#region 자손 객체 열거 가능형 구하기 - GetDescendantObjectEnumerable(sourceObject)

/// <summary>

/// 자손 객체 열거 가능형 구하기

/// </summary>

/// <param name="sourceObject">소스 객체</param>

/// <returns>자손 객체 열거 가능형</returns>

private IEnumerable<DependencyObject> GetDescendantObjectEnumerable(DependencyObject sourceObject)

{

Queue<DependencyObject> queue = new Queue<DependencyObject>();

int count1 = VisualTreeHelper.GetChildrenCount(sourceObject);

for(int i = 0; i < count1; i++)

{

DependencyObject childObject = VisualTreeHelper.GetChild(sourceObject, i);

yield return childObject;

queue.Enqueue(childObject);

}

while(queue.Count > 0)

{

DependencyObject parentObject = queue.Dequeue();

int count2 = VisualTreeHelper.GetChildrenCount(parentObject);

for(int i = 0; i < count2; i++)

{

DependencyObject childDependencyObject = VisualTreeHelper.GetChild(parentObject, i);

yield return childDependencyObject;

queue.Enqueue(childDependencyObject);

}

#endregion