[英]Cannot read a Bitmap image that I just saved in Base64
我嘗試加載圖片(PNG),將其保存在文本文件中的Base64中並重新加載,但是從文本加載圖片后,我只會看到淡淡的圖片(黑白,非常丑陋,與原始圖片相差甚遠!)。文件。 我的問題在哪里?
順便說一句,所有示例(從圖像文件加載圖片,保存到base64,從base64加載)均來自SO問題。
首先是從PNG文件加載圖片的方式:
try
{
var openFileDialog = new OpenFileDialog
{
CheckFileExists = true,
Multiselect = false,
DefaultExt = "png",
InitialDirectory =
Environment.GetFolderPath(Environment.SpecialFolder.MyPictures)
};
if (openFileDialog.ShowDialog() == true)
{
Bitmap img;
using (var stream = File.Open(openFileDialog.FileName, FileMode.Open, FileAccess.Read, FileShare.Read))
{
img = new Bitmap(stream);
}
Logo.Source = BitmapToImageSource(img);
}
}
catch (Exception exception)
{
MessageBox.Show(exception.ToString(), "An error occured", MessageBoxButton.OK, MessageBoxImage.Warning);
}
將其保存到base64:
try
{
Bitmap img = BitmapSourceToBitmap2((BitmapSource) Logo.Source);
string base64String;
using (var stream = new MemoryStream())
{
img.Save(stream, ImageFormat.Png);
byte[] imageBytes = stream.ToArray();
base64String = Convert.ToBase64String(imageBytes);
}
string fileName = string.Format(CultureInfo.InvariantCulture, "image{0:yyyyMMddHHmmss}.txt",
DateTime.Now);
string path = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), fileName);
using (var stream = File.Open(path, FileMode.CreateNew, FileAccess.Write, FileShare.None))
{
using (var writer = new StreamWriter(stream, System.Text.Encoding.UTF8))
{
writer.Write(base64String);
writer.Flush();
}
}
}
catch (Exception exception)
{
MessageBox.Show(exception.ToString(), "An error occured", MessageBoxButton.OK, MessageBoxImage.Warning);
}
BitmapSourceToBitmap2:
int width = srs.PixelWidth;
int height = srs.PixelHeight;
int stride = width*((srs.Format.BitsPerPixel + 7)/8);
IntPtr ptr = IntPtr.Zero;
try
{
ptr = Marshal.AllocHGlobal(height*stride);
srs.CopyPixels(new Int32Rect(0, 0, width, height), ptr, height*stride, stride);
using (var btm = new Bitmap(width, height, stride, PixelFormat.Format1bppIndexed, ptr))
{
// Clone the bitmap so that we can dispose it and
// release the unmanaged memory at ptr
return new Bitmap(btm);
}
}
finally
{
if (ptr != IntPtr.Zero)
Marshal.FreeHGlobal(ptr);
}
並將其從文件加載回:
try
{
var openFileDialog = new OpenFileDialog
{
CheckFileExists = true,
Multiselect = false,
DefaultExt = "txt",
InitialDirectory =
Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)
};
if (openFileDialog.ShowDialog() == true)
{
string base64String;
using (FileStream stream = File.Open(openFileDialog.FileName, FileMode.Open))
{
using (var reader = new StreamReader(stream))
{
base64String = reader.ReadToEnd();
}
}
byte[] binaryData = Convert.FromBase64String(base64String);
var bi = new BitmapImage();
bi.BeginInit();
bi.StreamSource = new MemoryStream(binaryData);
bi.EndInit();
Logo.Source = bi;
}
}
catch (Exception exception)
{
MessageBox.Show(exception.ToString(), "An error occured", MessageBoxButton.OK, MessageBoxImage.Warning);
}
這是一個簡短的代碼序列,它將JPG文件讀入字節數組,從中創建一個BitmapSource,然后將其編碼為base64字符串並將其寫入文件。
第二步,從文件中讀取base64字符串,進行解碼並創建第二個BitmapSource。
該示例假定存在一些XAML,其中包含兩個分別名為image1
和image2
Image元素。
第1步:
var imageFile = @"C:\Users\Clemens\Pictures\DSC06449.JPG";
var buffer = File.ReadAllBytes(imageFile);
using (var stream = new MemoryStream(buffer))
{
image1.Source = BitmapFrame.Create(
stream, BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
}
var base64File = @"C:\Users\Clemens\Pictures\DSC06449.b64";
var base64String = System.Convert.ToBase64String(buffer);
File.WriteAllText(base64File, base64String);
第2步:
base64String = File.ReadAllText(base64File);
buffer = System.Convert.FromBase64String(base64String);
using (var stream = new MemoryStream(buffer))
{
image2.Source = BitmapFrame.Create(
stream, BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
}
如果需要將已經存在的BitmapSource編碼為字節數組,請使用如下代碼:
var encoder = new PngBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(bitmapSource));
using (var stream = new MemoryStream())
{
encoder.Save(stream);
buffer = stream.ToArray();
}
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