windowsphone 瀑布流&ui虚拟化

瀑布流已经有点年代了吧，不过wp上还真是挺少资料的。今天抽空把自己之前搞过的东西写出来，避免大家重复劳动。

一、简单的瀑布流排版加入ui虚拟化。

最近看了 段博琼  ui虚拟化的一篇博文，链接：http://www.cnblogs.com/hebeiDGL/p/3410575.html

觉得还不错，于是下载了他的demo稍微改了一下瀑布流效果。

demo截图如下：

      

主要改动：

1：自定义WaterFallPanel继承Panel，用于实现瀑布流排版，并保持容器children距离顶部高度的信息：

public class WaterFallPanel : Panel
    {
        public WaterFallPanel()
        {
            /**默认2列**/
            ColumnCount = 2;
            ColumnHeight = new double[ColumnCount];
            childwidth = 480 / ColumnCount;
        }

        double childwidth;
        static double[] ColumnHeight;

        /// <summary>
        /// 列数
        /// </summary>
        public int ColumnCount
        {
            get { return (int)this.GetValue(ColumnCountProperty); }
            set { this.SetValue(ColumnCountProperty, value); }
        }


        public static DependencyProperty ColumnCountProperty = DependencyProperty.Register("WaterFallPanel", typeof(int), typeof(WaterFallPanel), new PropertyMetadata(new PropertyChangedCallback((o, e) =>
        {
            ColumnHeight = new double[(int)e.NewValue];
            if (o == null || e.NewValue == e.OldValue)
                return;
            o.SetValue(ColumnCountProperty, e.NewValue);
        })));


        protected override Size MeasureOverride(Size availableSize)
        {

            Size resultSize = new Size(0, 0);
            //List<DependencyObject> Children = this.GetVisualChildren().ToList();
            for (int i = 0; i < Children.Count; i++)
            {
                Children[i].Measure(availableSize);
            }
            #region 测量值
            for (int i = 0; i < ColumnHeight.Count(); i++)
            {
                ColumnHeight[i] = 0;
            }
            heightlist.Clear();
            for (int i = 0; i < Children.Count; i++)
            {
                double miniheight = ColumnHeight.Min();
                int h = 0;
                for (; h < ColumnHeight.Length; h++)
                {
                    if (ColumnHeight[h] == miniheight)
                    {
                        break;
                    }
                }
                ColumnHeight[h] += Children[i].DesiredSize.Height;

                heightlist.Add(ColumnHeight.Min());
            }
            #endregion

            resultSize.Height = ColumnHeight.Max();
            if (Children.Count == 0)
            {
                resultSize.Height = 0;
                resultSize.Width = 480;
            }
            else
            {
                resultSize.Width = (Children.Count + 1) * Children[0].DesiredSize.Width;
            }

            return resultSize;
        }

        protected override Size ArrangeOverride(Size finalSize)
        {
            for (int i = 0; i < ColumnHeight.Count(); i++)
            {
                ColumnHeight[i] = 0;
            }

            #region 排列值
            heightlist.Clear();
            for (int i = 0; i < Children.Count; i++)
            {
                double miniheight = ColumnHeight.Min();
                int h = 0;
                for (; h < ColumnHeight.Length; h++)
                {
                    if (ColumnHeight[h] == miniheight)
                    {
                        break;
                    }
                }
                Children[i].Arrange(new Rect(new Point(Children[i].DesiredSize.Width * h, ColumnHeight[h]), Children[i].DesiredSize));
                ColumnHeight[h] += Children[i].DesiredSize.Height;
                if (h == 0)
                {
                    if (Children[i].DesiredSize.Width > childwidth)
                    {
                        ColumnHeight[h + 1] += Children[i].DesiredSize.Height;
                    }
                }
                heightlist.Add(ColumnHeight.Min());
            }
            if (Children.Count < ColumnCount)
                finalSize.Width = childwidth * (Children.Count + 1);
            else
                finalSize.Width = childwidth * (ColumnCount + 1);


            #endregion


            return finalSize;
        }
        private List<double> heightlist = new List<double>();
        public double GetItemHeight(int item)
        {
            if (item >= 0 && item < heightlist.Count)
            {
                return heightlist[item];
            }
            else
            {
                return 0;
            }
        }
    }

View Code