Silverlight 背景平鋪——比較簡單的實現方法

         由於blend不夠普及，圖片平鋪問題在所難免。以前寫過如何在WPF中利用VisualBrush進行平鋪。但是在silverlihgt中是沒有VisualBrush的。那隻能通過代碼來控製圖片平鋪用了。

        在google中找了一些實現方法，但總感覺太複雜。比較經典的當然是Elite.Silverlight3.PixelShaders這個項目中的平鋪方法，但是過於複雜，並且不支援絕對的平鋪即需要指明在X軸平鋪數量和在Y軸的平鋪數量。即便是使用寬度除以圖片寬度來計算，也是稍顯麻煩。後來就找到了一個繼承於Panel的TitlePanel，這個是比較簡單的實現方法，切不用修改以往的代碼。貼上代碼以及樣本。
        

/*Copyright (c) 2008, WiredPrairie.usAll rights reserved.Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:    * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.    * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer         in the documentation and/or other materials provided with the distribution.    * Neither the name of the <ORGANIZATION> nor the names of its contributors may be used to endorse or promote products derived         from this software without specific prior written permission.THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENTOF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHERIN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISEDOF THE POSSIBILITY OF SUCH DAMAGE.   */using System;using System.Net;using System.Windows;using System.Windows.Controls;using System.Windows.Documents;using System.Windows.Ink;using System.Windows.Input;using System.Windows.Media;using System.Windows.Media.Animation;using System.Windows.Shapes;using System.Windows.Media.Imaging;using System.Diagnostics;namespace glPro.Common{    public class TilePanel : Panel    {        #region DependencyProperty setup        // Dependency properties for Tile Width, Height and Image        public static readonly DependencyProperty TileWidthProperty =            DependencyProperty.Register("TileWidth", typeof(double), typeof(TilePanel),                  new PropertyMetadata(double.NaN, new PropertyChangedCallback(TileWidthPropertyChanged)));        public static readonly DependencyProperty TileHeightProperty =            DependencyProperty.Register("TileHeight", typeof(double), typeof(TilePanel),                      new PropertyMetadata(double.NaN, new PropertyChangedCallback(TileHeightPropertyChanged)));        public static readonly DependencyProperty ImageProperty =            DependencyProperty.Register("Image", typeof(ImageBrush), typeof(TilePanel), new PropertyMetadata(null,                                                new PropertyChangedCallback(ImagePropertyChanged)));        public double TileWidth        {            get { return (double)GetValue(TileWidthProperty); }            set { SetValue(TileWidthProperty, value); }        }        public double TileHeight        {            get { return (double)GetValue(TileHeightProperty); }            set { SetValue(TileHeightProperty, value); }        }        public ImageBrush Image        {            get { return (ImageBrush)GetValue(ImageProperty); }            set { SetValue(ImageProperty, value); }        }        #endregion        private Size _lastFinalSize;        private ImageBrush _imgBrush;        private bool _needsUpdate = false;        public TilePanel()        {            this.SizeChanged += new SizeChangedEventHandler(TilePanelSizeChanged);        }        /// <summary>        /// Called when the size of the panel changes.        /// </summary>        /// <param name="sender">This panel</param>        /// <param name="e">The new size information</param>        protected virtual void TilePanelSizeChanged(object sender, SizeChangedEventArgs e)        {            if (e.NewSize != _lastFinalSize)            {                _lastFinalSize = e.NewSize;                // adjust the clipping rectangle based on the new size                RectangleGeometry rg = new RectangleGeometry();                rg.Rect = new Rect(new Point(), _lastFinalSize);                this.Clip = rg;                TileAdjustmentNeededAsync();            }                    }        /// <summary>        /// Signal that an adjustment to the tiles is needed,        /// then makes the call asynchronously.        /// By asynchronously making this call, it can help prevent        /// unnecessary work by the panel.        /// </summary>        protected void TileAdjustmentNeededAsync()        {            // by doing this sync, we can queue up several request            // but then really only handle the last one.            _needsUpdate = true;            // async call the adjust tiles            this.Dispatcher.BeginInvoke(delegate            {                AdjustTiles();            });        }                private static void TileHeightPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)        {            TilePanel tilePanel = d as TilePanel;            if (tilePanel != null)            {                Debug.WriteLine("TileHeight Changed: {0}", e.NewValue);                double val = (double)e.NewValue;                if ( val == double.NaN || val <= 0.0)                {                    throw new ArgumentOutOfRangeException("TileHeight");                }                tilePanel.TileAdjustmentNeededAsync();            }        }         private static void TileWidthPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)        {            TilePanel tilePanel = d as TilePanel;            if (tilePanel != null)            {                Debug.WriteLine("TileWidth Changed: {0}", e.NewValue);                double val = (double)e.NewValue;                if (val == double.NaN || val <= 0.0)                {                    throw new ArgumentOutOfRangeException("TileWidth");                }                tilePanel.TileAdjustmentNeededAsync();            }        }              private static void ImagePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)        {            // put code here to handle the property changed for Image            TilePanel tilePanel = d as TilePanel;            if (tilePanel != null )            {                Debug.WriteLine("ImagePropertyChanged");                tilePanel._imgBrush = e.NewValue as ImageBrush;                // remove all of the existing tiles as they no longer are valid                tilePanel.Children.Clear();                tilePanel.TileAdjustmentNeededAsync();            }        }         /// <summary>        /// Perform the standard Arrange. Here though, all of the tiles        /// are placed based on the tilesize specified.        /// </summary>        /// <param name="finalSize">the actual size that the panel has been given</param>        /// <returns>The size taken (which is always what it was given).</returns>        protected override Size ArrangeOverride(Size finalSize)        {            UIElementCollection children = Children;            double tw = TileWidth;            double th = TileHeight;            double x = 0, y = 0;            foreach (UIElement uie in Children)            {                if (x >= finalSize.Width)                {                    x = 0;                    y += th;                }                uie.Arrange(new Rect(x, y, tw, th));                x += tw;            }            return finalSize;        }        /// <summary>        /// Adjusts the quantity of the tiles based on the         /// size of the panel and immediately calls        /// UpdateLayout so the new tiles can be properly         /// layed out.        /// </summary>        protected virtual void AdjustTiles()        {            Debug.WriteLine("AdjustTiles - Update Needed: {0}", _needsUpdate);            // seems that it was already done ...            if (!_needsUpdate) { return; }            _needsUpdate = false;            // if no image brush is set ... all the children are cleared!            if (_imgBrush == null)             {                this.Children.Clear();                return ;             }            double tw = TileWidth;            double th = TileHeight;            // determine how many we actually need            int totalNeededX = (int) Math.Ceiling(this.ActualWidth / tw);            int totalNeededY = (int) Math.Ceiling(this.ActualHeight / th);            int totalNeeded = totalNeededX * totalNeededY;            // there may be too many             if (totalNeeded < this.Children.Count)            {                while (this.Children.Count > totalNeeded)                {                    this.Children.RemoveAt(this.Children.Count - 1);                                   }            }            // or too few ...            else if (this.Children.Count < totalNeeded)            {                while (this.Children.Count < totalNeeded)                {                    Rectangle r = new Rectangle();                    r.Width = tw;                    r.Height = th;                    r.Fill = _imgBrush;                    this.Children.Add(r);                                                        }            }            this.UpdateLayout();        }    }}

在xaml頁面中：引用此類： xmlns:local="clr-namespace:glPro.Common"

    <Grid>            <local:TilePanel  x:Name="pnlTile"                              TileWidth="4"                              TileHeight="61">                <local:TilePanel.Image>                    <ImageBrush ImageSource="Images/2-1上平鋪.png" />                </local:TilePanel.Image>            </local:TilePanel>        </Grid>

TileWidth是圖片的寬度，TileHeight是圖片的高度.其他的都是自動計算的。就這麼簡單。貼上找來的源碼。靠，才發現CSDN不能上傳源碼。抱歉！不過基本上代碼拷貝過去就能用。