标签:部分 empty win32 title imp debug contain mst set
一.前言
申明:WPF自定义控件与样式是一个系列文章,前后是有些关联的,但大多是按照由简到繁的顺序逐步发布的等,若有不明白的地方可以参考本系列前面的文章,文末附有部分文章链接。
本文主要针对WPF项目开发中图片的各种使用问题,经过总结,把一些经验分享一下。内容包括:
- WPF常用图像数据源ImageSource的创建;
- 自定义缩略图控件ThumbnailImage,支持网络图片、大图片、图片异步加载等特性;
- 动态图片gif播放控件;
- 图片列表样式,支持大数据量的虚拟化;
二. WPF常用图像数据源ImageSource的创建
Image Source="../Images/qq.png">Image>
这是一个普通Image控件的使用,Source的数据类型是ImageSource,在XAML中可以使用文件绝对路径或相对路径,ImageSource是一个抽象类,我们一般使用BitmapSource、BitmapImage等。
但在实际项目中,有各种各样的需求,比如:
-
- 从Bitmap创建ImageSource对象;
- 从数据流byte[]创建ImageSource对象;
- 从System.Drawing.Image创建ImageSource对象;
- 从一个大图片文件创建一个指定大小的ImageSource对象;
2.1 从System.Drawing.Image创建指定大小ImageSource对象
/// /// 使用System.Drawing.Image创建WPF使用的ImageSource类型缩略图(不放大小图)
/// ///
System.Drawing.Image 对象
///
指定宽度
///
指定高度
public static ImageSource CreateImageSourceThumbnia(System.Drawing.Image sourceImage, double width, double height)
{
if (sourceImage == null) return null;
double rw = width / sourceImage.Width;
double rh = height / sourceImage.Height;
var aspect = (float)Math.Min(rw, rh);
int w = sourceImage.Width, h = sourceImage.Height;
if (aspect 1)
{
w = (int)Math.Round(sourceImage.Width * aspect); h = (int)Math.Round(sourceImage.Height * aspect);
}
Bitmap sourceBmp = new Bitmap(sourceImage, w, h);
IntPtr hBitmap = sourceBmp.GetHbitmap();
BitmapSource bitmapSource = Imaging.CreateBitmapSourceFromHBitmap(hBitmap, IntPtr.Zero, Int32Rect.Empty,
BitmapSizeOptions.FromEmptyOptions());
bitmapSource.Freeze();
System.Utility.Win32.Win32.DeleteObject(hBitmap);
sourceImage.Dispose();
sourceBmp.Dispose();
return bitmapSource;
}
2.2 从一个大图片文件创建一个指定大小的ImageSource对象
/// /// 创建WPF使用的ImageSource类型缩略图(不放大小图)
/// ///
本地图片路径
///
指定宽度
///
指定高度
public static ImageSource CreateImageSourceThumbnia(string fileName, double width, double height)
{
System.Drawing.Image sourceImage = System.Drawing.Image.FromFile(fileName);
double rw = width / sourceImage.Width;
double rh = height / sourceImage.Height;
var aspect = (float)Math.Min(rw, rh);
int w = sourceImage.Width, h = sourceImage.Height;
if (aspect 1)
{
w = (int)Math.Round(sourceImage.Width * aspect); h = (int)Math.Round(sourceImage.Height * aspect);
}
Bitmap sourceBmp = new Bitmap(sourceImage, w, h);
IntPtr hBitmap = sourceBmp.GetHbitmap();
BitmapSource bitmapSource = Imaging.CreateBitmapSourceFromHBitmap(hBitmap, IntPtr.Zero, Int32Rect.Empty,
BitmapSizeOptions.FromEmptyOptions());
bitmapSource.Freeze();
System.Utility.Win32.Win32.DeleteObject(hBitmap);
sourceImage.Dispose();
sourceBmp.Dispose();
return bitmapSource;
}
2.3 从Bitmap创建指定大小的ImageSource对象
/// /// 从一个Bitmap创建ImageSource
/// ///
Bitmap对象
/// public static ImageSource CreateImageSourceFromImage(Bitmap image)
{
if (image == null) return null;
try
{
IntPtr ptr = image.GetHbitmap();
BitmapSource bs = Imaging.CreateBitmapSourceFromHBitmap(ptr, IntPtr.Zero, Int32Rect.Empty,
BitmapSizeOptions.FromEmptyOptions());
bs.Freeze();
image.Dispose();
System.Utility.Win32.Win32.DeleteObject(ptr);
return bs;
}
catch (Exception)
{
return null;
}
}
2.4 从数据流byte[]创建指定大小的ImageSource对象
/// /// 从数据流创建缩略图
/// public static ImageSource CreateImageSourceThumbnia(byte[] data, double width, double height)
{
using (Stream stream = new MemoryStream(data, true))
{
using (Image img = Image.FromStream(stream))
{
return CreateImageSourceThumbnia(img, width, height);
}
}
}
三.自定义缩略图控件ThumbnailImage
ThumbnailImage控件的主要解决的问题:
为了能扩展支持多种类型的缩略图,设计了一个简单的模式,用VS自带的工具生成的代码视图:
3.1 多种类型的缩略图扩展
首先定义一个图片类型枚举:
/// /// 缩略图数据源源类型
/// public enum EnumThumbnail
{
Image,
Vedio,
WebImage,
Auto,
FileX,
}
然后定义了一个接口,生成图片数据源ImageSource
/// /// 缩略图创建服务接口
/// public interface IThumbnailProvider
{
/// /// 创建缩略图。fileName:文件路径;width:图片宽度;height:高度
///
ImageSource GenereateThumbnail(object fileSource, double width, double height);
}
如上面的代码视图,有三个实现,视频缩略图VedioThumbnailProvider没有实现完成,基本方法是利用一个第三方工具ffmpeg来获取第一帧图像然后创建ImageSource。
ImageThumbnailProvider:普通图片缩略图实现(调用的2.2方法):
/// /// 本地图片缩略图创建服务
/// internal class ImageThumbnailProvider : IThumbnailProvider
{
/// /// 创建缩略图。fileName:文件路径;width:图片宽度;height:高度
/// public ImageSource GenereateThumbnail(object fileName, double width, double height)
{
try
{
var path = fileName.ToSafeString();
if (path.IsInvalid()) return null;
return System.Utility.Helper.Images.CreateImageSourceThumbnia(path, width, height);
}
catch
{
return null;
}
}
}
WebImageThumbnailProvider:网络图片缩略图实现(下载图片数据后调用2.1方法):
/// /// 网络图片缩略图创建服务
/// internal class WebImageThumbnailProvider : IThumbnailProvider
{
/// /// 创建缩略图。fileName:文件路径;width:图片宽度;height:高度
/// public ImageSource GenereateThumbnail(object fileName, double width, double height)
{
try
{
var path = fileName.ToSafeString();
if (path.IsInvalid()) return null;
var request = WebRequest.Create(path);
request.Timeout = 20000;
var stream = request.GetResponse().GetResponseStream();
var img = System.Drawing.Image.FromStream(stream);
return System.Utility.Helper.Images.CreateImageSourceThumbnia(img, width, height);
}
catch
{
return null;
}
}
}
简单工厂ThumbnailProviderFactory实现:
/// /// 缩略图创建服务简单工厂
/// public class ThumbnailProviderFactory : System.Utility.Patterns.ISimpleFactory
{
/// /// 根据key获取实例
/// public virtual IThumbnailProvider GetInstance(EnumThumbnail key)
{
switch (key)
{
case EnumThumbnail.Image:
return Singleton.GetInstance();
case EnumThumbnail.Vedio:
return Singleton.GetInstance();
case EnumThumbnail.WebImage:
return Singleton.GetInstance();
}
return null;
}
}
3.2 缩略图控件ThumbnailImage
先看看效果图吧,下面三张图片,图1是本地图片,图2是网络图片,图3也是网络图片,为什么没显示呢,这张图片用的是国外的图片链接地址,异步加载(加载比较慢,还没出来的!)
ThumbnailImage实际是继承在微软的图片控件Image,因此没有样式代码,继承之后,主要的目的就是重写Imagesource的处理过程,详细代码:
/*
* 较大的图片,视频,网络图片要做缓存处理:缓存缩略图为本地文件,或内存缩略图对象。
*/
/// /// 缩略图图片显示控件,同时支持图片和视频缩略图
/// public class ThumbnailImage : Image
{
/// /// 是否启用缓存,默认false不启用
/// public bool CacheEnable
{
get { return (bool)GetValue(CacheEnableProperty); }
set { SetValue(CacheEnableProperty, value); }
}
/// /// 是否启用缓存,默认false不启用.默认缓存时间是180秒
/// public static readonly DependencyProperty CacheEnableProperty =
DependencyProperty.Register("CacheEnable", typeof(bool), typeof(ThumbnailImage), new PropertyMetadata(false));
/// /// 缓存时间,单位秒。默认180秒
/// public int CacheTime
{
get { return (int)GetValue(CacheTimeProperty); }
set { SetValue(CacheTimeProperty, value); }
}
public static readonly DependencyProperty CacheTimeProperty =
DependencyProperty.Register("CacheTime", typeof(int), typeof(ThumbnailImage), new PropertyMetadata(180));
/// /// 是否启用异步加载,网络图片建议启用,本地图可以不需要。默认不起用异步
/// public bool AsyncEnable
{
get { return (bool)GetValue(AsyncEnableProperty); }
set { SetValue(AsyncEnableProperty, value); }
}
public static readonly DependencyProperty AsyncEnableProperty =
DependencyProperty.Register("AsyncEnable", typeof(bool), typeof(ThumbnailImage), new PropertyMetadata(false));
/// /// 缩略图类型,默认Image图片
/// public EnumThumbnail ThumbnailType
{
get { return (EnumThumbnail)GetValue(ThumbnailTypeProperty); }
set { SetValue(ThumbnailTypeProperty, value); }
}
public static readonly DependencyProperty ThumbnailTypeProperty =
DependencyProperty.Register("ThumbnailType", typeof(EnumThumbnail), typeof(ThumbnailImage), new PropertyMetadata(EnumThumbnail.Image));
/// /// 缩略图数据源:文件物理路径
/// public object ThumbnailSource
{
get { return GetValue(ThumbnailSourceProperty); }
set { SetValue(ThumbnailSourceProperty, value); }
}
public static readonly DependencyProperty ThumbnailSourceProperty = DependencyProperty.Register("ThumbnailSource", typeof(object),
typeof(ThumbnailImage), new PropertyMetadata(OnSourcePropertyChanged));
/// /// 缩略图
/// protected static ThumbnailProviderFactory ThumbnailProviderFactory = new ThumbnailProviderFactory();
protected override void OnInitialized(EventArgs e)
{
base.OnInitialized(e);
this.Loaded += ThumbnailImage_Loaded;
}
void ThumbnailImage_Loaded(object sender, RoutedEventArgs e)
{
BindSource(this);
}
/// /// 属性更改处理事件
/// private static void OnSourcePropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args)
{
ThumbnailImage img = sender as ThumbnailImage;
if (img == null) return;
if (!img.IsLoaded) return;
BindSource(img);
}
private static void BindSource(ThumbnailImage image)
{
var w = image.Width;
var h = image.Height;
object source = image.ThumbnailSource;
//bind
if (image.AsyncEnable)
{
BindThumbnialAync(image, source, w, h);
}
else
{
BindThumbnial(image, source, w, h);
}
}
/// /// 绑定缩略图
/// private static void BindThumbnial(ThumbnailImage image, object fileSource, double w, double h)
{
IThumbnailProvider thumbnailProvider = ThumbnailProviderFactory.GetInstance(image.ThumbnailType);
image.Dispatcher.BeginInvoke(new Action(() =>
{
var cache = image.CacheEnable;
var time = image.CacheTime;
ImageSource img = null;
if (cache)
{
img = CacheManager.GetCache(fileSource.GetHashCode().ToString(), time, () =>
{
return thumbnailProvider.GenereateThumbnail(fileSource, w, h);
});
}
else img = thumbnailProvider.GenereateThumbnail(fileSource, w, h);
image.Source = img;
}), DispatcherPriority.ApplicationIdle);
}
/// /// 异步线程池绑定缩略图
/// private