SharpDX之Direct2D教程II——加载位图文件和保存位图文件
本系列文章目录：
SharpDX之Direct2D教程I——简单示例和Color（颜色）
绘制位图是绘制操作的不可缺少的一部分。在Direct2D中绘制位图，必须先利用WIC组件将位图加载到内存中，再绘制到RenderTarget中去
在SharpDX中绘制位图，分成两个部分：
利用WIC在SharpDX中加载位图，生成Bitmap对象
利用RenderTarget对象的DrawBitmap方法把Bitmap对象绘制到RenderTarget中去
利用WIC在SharpDX中加载位图文件
利用WIC在SharpDX中绘制位图文件的核心内容就是把位图文件转换为Bitmap对象。它的操作过程如下：
1、创建WIC的ImagingFactory类。
2、根据位图文件创建BitmapDecoder对象（实际上调用系统解码器解析位图文件）。
BitmapDecoder对象有1个属性和1个函数
FrameCount属性：只读属性，说明该位图对象包含的帧数。一般gif文件能包含多个帧，其余格式的一般只有1个帧
GetFrame函数：返回指定帧对象。参数index是整形，说明是第几帧（从0开始）。返回的是BitmapFrameDecode对象
3、利用BitmapDecoder对象的GetFrame函数，返回指定帧的BitmapFrameDecode对象。（参数index一般是0，返回第1帧）
一般情况下，到此就可以了。但是，位图格式有很多，你可能不是很确定你的位图格式是否兼容SharpDX的Bitmap对象。因此，比较好的做法是继续下面的步骤，将位图格式转换为兼容SharpDX的Bitmap对象
4、创建FormatConverter对象。该对象负责进行格式转换。
5、调用FormatConverter对象的Initialize方法，进行格式转换。
6、最后，利用Bitmap对象的FromWicBitmap函数将之前的FormatConverter对象转换为SharpDX的Bitmap对象
和Windows API Code Pack 1.1中的Direct2D略有不同的是，BitmapFrameDecode对象和FormatConverter对象都继承BitmapSource对象，省去了一个转换的过程
下面是代码
Protected Function LoadBitmap(Render As D2D.RenderTarget, File As String, FrameIndex As Integer) As D2D.Bitmap
Dim Decoder As New WIC.BitmapDecoder(_ImagingFactory, File, DX.IO.NativeFileAccess.Read, WIC.DecodeOptions.CacheOnLoad)
If FrameIndex > Decoder.FrameCount - 1 OrElse FrameIndex < 0 Then FrameIndex = 0
Dim Source As WIC.BitmapFrameDecode = Decoder.GetFrame(FrameIndex)
Dim Converter As New WIC.FormatConverter(_ImagingFactory)
Converter.Initialize(Source, WIC.PixelFormat.Format32bppPBGRA)
Return D2D.Bitmap.FromWicBitmap(Render, Converter)
End Function
利用RenderTarget对象的DrawBitmap方法把Bitmap对象绘制到RenderTarget中去
下面是DrawBitmap方法的原型定义：
Public Sub DrawBitmap(bitmap As D2D.Bitmap, destinationRectangle As DX.RectangleF, opacity As Single, interpolationMode As D2D.BitmapInterpolationMode, sourceRectangle As DX.RectangleF)
Public Sub DrawBitmap(bitmap As D2D.Bitmap, opacity As Single, interpolationMode As D2D.BitmapInterpolationMode)
Public Sub DrawBitmap(bitmap As D2D.Bitmap, destinationRectangle As DX.RectangleF, opacity As Single, interpolationMode As D2D.BitmapInterpolationMode)
Public Sub DrawBitmap(bitmap As D2D.Bitmap, opacity As Single, interpolationMode As D2D.BitmapInterpolationMode, sourceRectangle As DX.RectangleF)
参数的意义如下：
bitmap：要绘制的Bitmap对象
destinationRectangle：绘制在RenderTarget对象上的目标范围。缺省是在RenderTarget对象的左上角，宽高是Bitmap对象的宽高
opacity：不透明度
interpolationMode：图像缩放时的插值算法，是个枚举
sourceRectangle：要绘制的源目标范围。缺省是Bitmap对象的整个范围
下面是示例代码
Public Class clsSharpDXLoadBitmap
Inherits clsSharpDXSampleBase
Protected _ImagingFactory As WIC.ImagingFactory
Public Shadows Sub CreateDeviceResource(Target As Control)
MyBase.CreateDeviceResource(Target)
_ImagingFactory = New WIC.ImagingFactory
End Sub
Public Function LoadBitmap(File As String, Optional FrameIndex As Integer = 0) As D2D.Bitmap
Return LoadBitmap(_RenderTarget, File, FrameIndex)
End Function
Protected Function LoadBitmap(Render As D2D.RenderTarget, File As String, FrameIndex As Integer) As D2D.Bitmap
Dim Decoder As New WIC.BitmapDecoder(_ImagingFactory, File, DX.IO.NativeFileAccess.Read, WIC.DecodeOptions.CacheOnLoad)
If FrameIndex > Decoder.FrameCount - 1 OrElse FrameIndex < 0 Then FrameIndex = 0
Dim Source As WIC.BitmapFrameDecode = Decoder.GetFrame(FrameIndex)
Dim Converter As New WIC.FormatConverter(_ImagingFactory)
Converter.Initialize(Source, WIC.PixelFormat.Format32bppPBGRA)
Return D2D.Bitmap.FromWicBitmap(Render, Converter)
End Function
Public Shadows Sub Render()
With _RenderTarget
.BeginDraw()
.Clear(DX.Color.Honeydew.ToColor4)
Dim B As D2D.Bitmap = LoadBitmap("216.png")
.DrawBitmap(B, 1, SharpDX.Direct2D1.BitmapInterpolationMode.NearestNeighbor, New DX.RectangleF(0, 0, 260, 260))
.EndDraw()
End With
End Sub
End Class
利用WIC保存图片
WIC既能负责图片的解码，也能负责图片的编码。我们也可以利用WIC编码图片。
在调试的时候出了问题，先看看下面两段代码
Public Class Class1
Public Shared Sub Test()
Dim wicFactory As WIC.ImagingFactory = New WIC.ImagingFactory
Dim F As String = "333.png"
If (File.Exists(F)) Then File.Delete(F)
Dim spStream As WIC.WICStream = New WIC.WICStream(wicFactory, F, NativeFileAccess.Write)
Dim spBitmapEncoder As WIC.PngBitmapEncoder = New WIC.PngBitmapEncoder(wicFactory)
spBitmapEncoder.Initialize(spStream)
End Sub
End Class
上面的代码是用VB2010写的，仅仅写到PngBitmapEncoder对象的Initialize方法。
再看看下面这段代码，用的是C# 2010写的
class Class1
{
public static void test()
{
ImagingFactory wicFactory = new ImagingFactory();
string F = "333.png";
if (File.Exists(F)) File.Delete(F);
WICStream stream = new WICStream(wicFactory, F, NativeFileAccess.Write);
PngBitmapEncoder encoder = new PngBitmapEncoder(wicFactory);
encoder.Initialize(stream);
}
}
可以看出，两段代码没什么不同（仅仅是语法上的不同而已），但是VB2010的代码在执行到Initialize时总是报错（内部错误），而C#2010在执行到Initialize方法很顺利的完成了。两段代码引用的是同一个动态库SharpDX的2.5.0的库。
我解释不出是什么原因，只能归结于SharpDX自身的原因了。
不过，我发现一个问题，写在这儿，给大家一个参考，也许谁能给出解决方案。（或者是我的设置有问题？）
在VB2010中，PngBitmapEncoder类的初始方法只能看到两个，New(Object)和New(IntPtr)
在C#2010中，PngBitmapEncoder类的初始方法能看到六个，除了上面的两个，还多了很多
打开SharpDX.Direct2D1.xml中也看到PngBitmapEncoder对象的初始方法有六个
难道SharpDX真的不能很好的运用于VB2010中么？
最后贴一段SharpDX中自带示例中的WIC保存图片的代码
using System;
using System.IO;
using SharpDX;
using SharpDX.Direct2D1;
using SharpDX.DXGI;
using SharpDX.IO;
using SharpDX.WIC;
using AlphaMode = SharpDX.Direct2D1.AlphaMode;
using Bitmap = SharpDX.WIC.Bitmap;
using PixelFormat = SharpDX.Direct2D1.PixelFormat;
namespace RenderToWicApp
{
internal static class Program
{
private static void Main()
{
var wicFactory = new ImagingFactory();
var d2dFactory = new SharpDX.Direct2D1.Factory();
string filename = "output.png";
const int width = 512;
const int height = 512;
var rectangleGeometry = new RoundedRectangleGeometry(d2dFactory, new RoundedRectangle() { RadiusX = 32, RadiusY = 32, Rect = new RectangleF(128, 128, width - 128 * 2, height-128 * 2) });
var wicBitmap = new Bitmap(wicFactory, width, height, SharpDX.WIC.PixelFormat.Format32bppBGR, BitmapCreateCacheOption.CacheOnLoad);
var renderTargetProperties = new RenderTargetProperties(RenderTargetType.Default, new PixelFormat(Format.Unknown, AlphaMode.Unknown), 0, 0, RenderTargetUsage.None, FeatureLevel.Level_DEFAULT);
var d2dRenderTarget = new WicRenderTarget(d2dFactory, wicBitmap, renderTargetProperties);
var solidColorBrush = new SolidColorBrush(d2dRenderTarget, Color.White);
d2dRenderTarget.BeginDraw();
d2dRenderTarget.Clear(Color.Black);
d2dRenderTarget.FillGeometry(rectangleGeometry, solidColorBrush, null);
d2dRenderTarget.EndDraw();
if (File.Exists(filename))
File.Delete(filename);
var stream = new WICStream(wicFactory, filename, NativeFileAccess.Write);
var encoder = new PngBitmapEncoder(wicFactory);
encoder.Initialize(stream);
var bitmapFrameEncode = new BitmapFrameEncode(encoder);
bitmapFrameEncode.Initialize();
bitmapFrameEncode.SetSize(width, height);
var pixelFormatGuid = SharpDX.WIC.PixelFormat.FormatDontCare;
bitmapFrameEncode.SetPixelFormat(ref pixelFormatGuid);
bitmapFrameEncode.WriteSource(wicBitmap);
bitmapFrameEncode.Commit();
encoder.Commit();
bitmapFrameEncode.Dispose();
encoder.Dispose();
stream.Dispose();
System.Diagnostics.Process.Start(Path.GetFullPath(Path.Combine(Environment.CurrentDirectory,filename)));
}
}
}
