[feat]分页的基本代码完成

Author: teacher-zhou

src/TDesign/Components/TPagination.cs

@@ -0,0 +1,186 @@
+using Microsoft.AspNetCore.Components.Rendering;
+
+namespace TDesign;
+/// <summary>
+/// 用于模块内切换内容的分页
+/// </summary>
+[CssClass("t-pagination")]
+public class TPagination:BlazorComponentBase
+{
+    #region 参数
+    /// <summary>
+    /// 设置分页组件的大小。
+    /// </summary>
+    [Parameter][BooleanCssClass("t-size-s","t-size-m")] public bool Small { get; set; }
+
+    #region Current
+    /// <summary>
+    /// 设置当前页码。
+    /// </summary>
+    [Parameter][EditorRequired]public int Current { get; set; }
+    /// <summary>
+    /// 设置一个当页码变更时的回调方法。
+    /// </summary>
+    [Parameter] public EventCallback<int> CurrentChanged { get; set; }
+    #endregion
+
+    #region PageSize
+    /// <summary>
+    /// 设置每一页的数据量。默认是 10。
+    /// </summary>
+    [Parameter] [EditorRequired]public int PageSize { get; set; } = 10;
+    /// <summary>
+    /// 设置一个当每页数据量变更时的回调方法。
+    /// </summary>
+    [Parameter]public EventCallback<int> PageSizeChanged { get; set; }
+    #endregion
+
+    #region Total
+    /// <summary>
+    /// 设置分页的总数据量。必须要大于 0。
+    /// </summary>
+    [Parameter][EditorRequired]public long Total { get; set; }
+    /// <summary>
+    /// 设置一个当总数据量变化时的回调方法。
+    /// </summary>
+    [Parameter]public EventCallback<long> TotalChanged { get; set; }
+    /// <summary>
+    /// 设置显示总数据量的任意内容。
+    /// </summary>
+    [Parameter]public RenderFragment<long>? TotalContent { get; set; }
+    /// <summary>
+    /// 设置一个布尔值，表示是否显示总数据量的内容。
+    /// </summary>
+    [Parameter]public bool ShowTotal { get; set; }
+    #endregion
+
+    /// <summary>
+    /// 设置分页页码条的显示数量。建议范围在 5-21 之间，默认是 7。
+    /// </summary>
+    [Parameter] public int PageNumber { get; set; } = 7;
+    #endregion
+
+
+    #region Internal Property
+    /// <summary>
+    /// 获取总页数。
+    /// </summary>
+    long TotalPages
+    {
+        get
+        {
+            var total = Total + PageSize - 1;
+            if ( total <= 0 )
+            {
+                total = 1;
+            }
+
+            var result = total / PageSize;
+            if ( result < 0 )
+            {
+                result = 1;
+            }
+            return result;
+        }
+    }
+    #endregion
+
+    #region Method
+    /// <inheritdoc/>
+    protected override void OnParametersSet()
+    {
+        base.OnParametersSet();
+
+        if ( Current <= 0 )
+        {
+            throw new ArgumentException($"{nameof(Current)} 必须大于0");
+        }
+        if ( PageSize <= 0 )
+        {
+            throw new ArgumentException($"{nameof(PageSize)} 必须大于0");
+        }
+        if ( Total <= 0 )
+        {
+            throw new ArgumentException($"{nameof(Total)} 必须大于0");
+        }
+    }
+
+    protected override void AddContent(RenderTreeBuilder builder, int sequence)
+    {
+        BuildTotal(builder, sequence);
+        BuildPrevOrNextBtn(builder, sequence + 1, true);
+        BuildPageNumbers(builder, sequence + 2);
+        BuildPrevOrNextBtn(builder, sequence + 3, false);
+    }
+
+    /// <summary>
+    /// 构建总数据量的元素。
+    /// </summary>
+    void BuildTotal(RenderTreeBuilder builder, int sequence) => builder.CreateElement(sequence, "div", TotalContent?.Invoke(Total), new { @class = "t-pagination__total" }, ShowTotal);
+
+    /// <summary>
+    /// 构建上一页或下一页按钮。
+    /// </summary>
+    /// <param name="builder"></param>
+    /// <param name="sequence"></param>
+    /// <param name="prevOrNext"><c>true</c> 表示上一页，否则是下一页。</param>
+    void BuildPrevOrNextBtn(RenderTreeBuilder builder, int sequence,bool prevOrNext)
+    {
+        builder.CreateElement(sequence, "div", content =>
+        {
+            content.CreateComponent<TIcon>(0, attributes: new { Name = prevOrNext ? IconName.ChevronLeft : IconName.ChevronRight });
+        }, new { @class = HtmlHelper.CreateCssBuilder().Append("t-pagination__btn").Append("t-pagination__btn-prev", prevOrNext).Append("t-pagination__btn-next") });
+    }
+
+    void BuildPageNumbers(RenderTreeBuilder builder, int sequence)
+    {
+        builder.CreateElement(sequence, "ul", content =>
+        {
+            var (start, end) = ComputePageNumber();
+            for ( long i = start; i <=end; i++ )
+            {
+                content.CreateElement((int)i, "li", i.ToString(), new { @class = "t-pagination__number" });
+            }
+
+        }, new { @class = "t-pagination__pager" });
+
+
+        /// <summary>
+        /// 计算分页页码的开始和结束的页码。
+        /// </summary>
+        /// <returns>开始和结束的页码。</returns>
+        (long start, long end) ComputePageNumber()
+        {
+            var start = 0L;
+            var end = 0L;
+
+            var middle = PageNumber / 2;
+            if ( Current <= middle )
+            {
+                start = 1;
+                end = PageNumber;
+            }
+            else if ( Current > middle )
+            {
+                start = Current - middle;
+                end = Current + middle;
+            }
+            if ( end > TotalPages )
+            {
+                end = TotalPages;
+                if ( start + end != PageNumber - 2 )
+                {
+                    start = end - PageNumber + 2 - 1;
+                }
+            }
+            if ( end <= PageNumber )
+            {
+                start = 1;
+            }
+
+            return (start, end);
+        }
+    }
+
+    #endregion
+}