Win8 Metro(C#) 数字图像处理--1 图像打开，保存

原文:Win8 Metro(C#) 数字图像处理--1 图像打开，保存

作为本专栏的第一篇，必不可少的需要介绍一下图像的打开与保存，一便大家后面DEMO的制作。

  Win8Metro编程中，图像相关的操作基本都是以流的形式进行的，图像对象类型在Metro主要表现为两种形式：BitmapImage和WriteableBitmap，图像的显示控件为Image。

  我们可以用如下方式打开和显示一幅图像对象。

BitmapImage srcImage=newBitmapImage (new Uri(“UriPath”), UriKind.Relative)

  其中UriPath为图像的Uri地址，UriKind表示路径的选择，Urikind.Relative表示是相对路径，也可以选择绝对路径Urikind.Absolute，或者Urikind.
RelativeOrAbsolute。

Image imageBox=newImage ();

imageBox.Source=srcImage;//将图像显示在imageBox控件中

  还有一种方法则是使用WriteableBitmap对象，这也是我这里要详细介绍的方法。

1.图像打开

        privatestaticBitmapImage srcImage =newBitmapImage();

        privatestaticWriteableBitmap
wbsrcImage;

       //open image fuctiondefinition

        privateasyncvoid
OpenImage()

        {

            FileOpenPicker imagePicker =newFileOpenPicker

            {

               
ViewMode = PickerViewMode.Thumbnail,

               SuggestedStartLocation =PickerLocationId.PicturesLibrary,

               
FileTypeFilter = { ".jpg",".jpeg",".png",".bmp"
}

            };

            Guid decoderId;

            StorageFile imageFile =await
imagePicker.PickSingleFileAsync();

            if (imageFile !=null)

            {

               
srcImage = newBitmapImage();

               
using (IRandomAccessStream stream =await
imageFile.OpenAsync(FileAccessMode.Read))

               
{

                   srcImage.SetSource(stream);

                   
switch (imageFile.FileType.ToLower())

                   
{

                       case".jpg":

                       case".jpeg":

                           decoderId = Windows.Graphics.Imaging.BitmapDecoder.JpegDecoderId;

                           break;

                       case".bmp":

                           decoderId = Windows.Graphics.Imaging.BitmapDecoder.BmpDecoderId;

                           break;

                       case".png":

                           decoderId = Windows.Graphics.Imaging.BitmapDecoder.PngDecoderId;

                           break;

                       default:

                  
         return;

                   
}

                   Windows.Graphics.Imaging.BitmapDecoder decoder =await
Windows.Graphics.Imaging.BitmapDecoder.CreateAsync(decoderId, stream);

                   
int width = (int)decoder.PixelWidth;

             
      int height = (int)decoder.PixelHeight;

                   Windows.Graphics.Imaging.PixelDataProvider dataprovider =await
decoder.GetPixelDataAsync();

                   
byte[] pixels =dataprovider.DetachPixelData();

                   
wbsrcImage = newWriteableBitmap(width, height);

                   
Stream pixelStream =wbsrcImage.PixelBuffer.AsStream();

                   
//rgba in original  

                   
//to display ,convert tobgra  

                   
for (int i = 0; i < pixels.Length; i += 4)

                   
{

                       byte temp = pixels[i];

                       pixels[i] =pixels[i + 2];

                       pixels[i +2] = temp;

                   
}

                   pixelStream.Write(pixels, 0, pixels.Length);

                   pixelStream.Dispose();

                   stream.Dispose();

               
}

               
ImageOne.Source =wbsrcImage;

               
ImageOne.Width =wbsrcImage.PixelWidth;

               
ImageOne.Height =wbsrcImage.PixelHeight;

            }

        }

2.图像保存

//save image fuction definition

        privateasyncvoid
SaveImage(WriteableBitmap src)

        {

            FileSavePicker save =newFileSavePicker();

           save.SuggestedStartLocation =PickerLocationId.PicturesLibrary;

           save.DefaultFileExtension =".jpg";

            save.SuggestedFileName ="newimage";

           save.FileTypeChoices.Add(".bmp",newList<string>()
{ ".bmp" });

           save.FileTypeChoices.Add(".png",newList<string>()
{ ".png" });

           save.FileTypeChoices.Add(".jpg",newList<string>()
{ ".jpg",".jpeg" });

            StorageFile savedItem =await
save.PickSaveFileAsync();

            try

            {

               
Guid encoderId;

               
switch (savedItem.FileType.ToLower())

               
{

                   
case".jpg":

                       encoderId =BitmapEncoder.JpegEncoderId;

                       break;

                   
case".bmp":

                       encoderId =BitmapEncoder.BmpEncoderId;

                       break;

                   
case".png":

                   
default:

                       encoderId =BitmapEncoder.PngEncoderId;

                       break;

               
}

               
IRandomAccessStream fileStream =await savedItem.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);

               
BitmapEncoder encoder =awaitBitmapEncoder.CreateAsync(encoderId,
fileStream);

               
Stream pixelStream =src.PixelBuffer.AsStream();

                byte[] pixels =newbyte[pixelStream.Length];

               pixelStream.Read(pixels, 0, pixels.Length);

              
//pixal format shouldconvert to rgba8

               
for (int i = 0; i < pixels.Length; i += 4)

               
{

                    byte temp = pixels[i];

                   
pixels[i] =pixels[i + 2];

                   
pixels[i + 2] =temp;

               
}

               encoder.SetPixelData(

               
BitmapPixelFormat.Rgba8,

               
BitmapAlphaMode.Straight,

               
(uint)src.PixelWidth,

               
(uint)src.PixelHeight,

               
96, // Horizontal DPI

               
96, // Vertical DPI

               
pixels

               
);

               
await encoder.FlushAsync();

            }

            catch (Exception
e)

            {

               
throw e;

            }

        }

最后，分享一个专业的图像处理网站（微像素），里面有很多源代码下载：

http://www.zealpixel.com/portal.php