I'd like to open a .jpg file in WPF, scale it down to around 50%, then save it back to the file system. What's a good/efficient way to go about doing that?
If you want to save on the memory usage you should look into specifying DecodePixelWidth/DecodePixelHeight on BitmapImage or the JpegDecoder.
The scaling can be accomplished using TransformedBitmap.
I have used 2 functions here. ResizeImage accepts Original Image as Byte Array and target size in pixel. This function Returns resized Image as Byte Array. You can write it in file.
Follow these steps
1) Read Image as Byte array using BinaryReader
2) Call ResizeImage function by Passing this array and target size of imag.
3) Store Returned value in Byte array
4) Write it to file using BinaryWriter
byte[] ResizeImage(byte[] imageFile, int targetSize)
{
System.Drawing.Image oldImage = System.Drawing.Image.FromStream(new MemoryStream(imageFile));
System.Drawing.Size newSize = CalculateDimensions(oldImage.Size, targetSize);
using (System.Drawing.Bitmap newImage = new System.Drawing.Bitmap(oldImage, (int)newSize.Width, (int)newSize.Height))
{
using (System.Drawing.Graphics canvas = System.Drawing.Graphics.FromImage(newImage))
{
canvas.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
canvas.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
canvas.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
canvas.DrawImage(oldImage, new System.Drawing.Rectangle(new System.Drawing.Point(0, 0), newSize));
MemoryStream m = new MemoryStream();
newImage.Save(m, System.Drawing.Imaging.ImageFormat.Jpeg);
return m.GetBuffer();
}
}
}
System.Drawing.Size CalculateDimensions(System.Drawing.Size oldSize, int targetSize)
{
System.Drawing.Size newSize = new System.Drawing.Size();
if (oldSize.Height > oldSize.Width)
{
newSize.Width = (int)(oldSize.Width * ((float)targetSize / (float)oldSize.Height));
newSize.Height = targetSize;
}
else
{
newSize.Width = targetSize;
newSize.Height = (int)(oldSize.Height * ((float)targetSize / (float)oldSize.Width));
}
return newSize;
}
Take a look at the answer with the most upvotes to this question. It offers a helper class for manipulating images. Take a look at the ResizeImage function and SaveJpeg function.
EDIT:
I have found something more WPF-specific here.
Related
I'm kind of new to Silverlight. I've managed to solve this problem for WPF, unfortunately not for Silverlight.
I open an image with an OpenFileDialog. I make a stream out of it and write it in a byte array. This byte array is then put into the database. This is the code I use to open the image and convert it into a byte array:
OpenFileDialog dlg = new OpenFileDialog();
dlg.InitialDirectory = #"C:\";
dlg.Filter = "Image File (*.jpg;*.bmp;*.gif)|*.jpg;*.bmp;*.gif";
dlg.FilterIndex = 1;
if(dlg.ShowDialog() == true)
{
pImage.Naam = dlg.File.Name;
BitmapImage bitImage = new BitmapImage();
Stream s = (Stream)dlg.File.OpenRead();
imgItem.Source = bitImage;
pImage.Data = new byte[s.Length];
s.Read(pImage.Data, 0, (int)s.Length);
s.Close();
}
I manage to save the byte array as a varbinary without any problem to my database.
When I retrieve it, I have no difficulties converting the varbinary back to the byte array (I'm pretty sure the two byte arrays are the same as when debugging I get exactly the same size).
But then I get stuck! Whenever I want to convert the byte array back to an image using the following code, my stream (and thus my image) is empty:
var newImage = new BitmapImage();
var myStream = new MemoryStream(pHuidigeImage.Data);
newImage.SetSource(myStream);
imgItem.Source = newImage;
So, what's wrong here?
Thanks in advance!
I'm building a small app using C#/WPF.
The application receives (from an unmanaged C++ library) a byte array (byte[]) from a bitmap source
In my WPF window, I have an (System.windows.Controls.Image) image which I will use to display the bitmap.
In the code behind (C#) I need to able to take that byte array, create BitmapSource /ImageSource and assign the source for my image control.
// byte array source from unmanaged librariy
byte[] imageData;
// Image Control Definition
System.Windows.Controls.Image image = new Image() {width = 100, height = 100 };
// Assign the Image Source
image.Source = ConvertByteArrayToImageSource(imageData);
private BitmapSource ConvertByteArrayToImagesource(byte[] imageData)
{
??????????
}
I've been working on this for a bit here and haven't been able to figure this out. I've tried several solutions that I've found by goolging around. To date, I haven't been able to figure this out.
I've tried:
1) Creating a BitmapSource
var stride = ((width * PixelFormats.Bgr24 +31) ?32) *4);
var imageSrc = BitmapSource.Create(width, height, 96d, 96d, PixelFormats.Bgr24, null, imageData, stride);
That through a runtime exception saying buffer was too small
Buffer size is not sufficient
2) I tried using a memory stream:
BitmapImage bitmapImage = new BitmapImage();
using (var mem = new MemoryStream(imageData))
{
bitmapImage.BeginInit();
bitmapImage.CrateOptions = BitmapCreateOptions.PreservePixelFormat;
bitmapImage.CacheOption = BitmapCacheOption.OnLoad;
bitmapImage.StreamSource = mem;
bitmapImage.EndInit();
return bitmapImage;
}
This code through an exception on the EndInit() call.
"No imaging component suitableto complete this operation was found."
SOS! I've spent a couple of days on this one and am clearly stuck.
Any help/ideas/direction would be greatly appreciated.
Thanks,
JohnB
Your stride calculation is wrong. It is the number of full bytes per scan line, and should therefore be calculated like this:
var format = PixelFormats.Bgr24;
var stride = (width * format.BitsPerPixel + 7) / 8;
var imageSrc = BitmapSource.Create(
width, height, 96d, 96d, format, null, imageData, stride);
Of course you also have to make sure that you use the correct image size, i.e. that the width and height values actually correspond with the data in imageBuffer.
I have a byte[] that represents the raw data of an image. I would like to convert it to a BitmapImage.
I tried several examples I found but I kept getting the following exception
"No imaging component suitable to complete this operation was found."
I think it is because my byte[] does not actually represent an Image but only the raw bits.
so my question is as mentioned above is how to convert a byte[] of raw bits to a BitmapImage.
The code below does not create a BitmapSource from a raw pixel buffer, as asked in the question.
But in case you want to create a BitmapImage from an encoded frame like a PNG or a JPEG, you would do it like this:
public static BitmapImage LoadFromBytes(byte[] bytes)
{
using (var stream = new MemoryStream(bytes))
{
var image = new BitmapImage();
image.BeginInit();
image.CacheOption = BitmapCacheOption.OnLoad;
image.StreamSource = stream;
image.EndInit();
return image;
}
}
When your byte array contains a bitmap's raw pixel data, you may create a BitmapSource (which is the base class of BitmapImage) by the static method BitmapSource.Create.
However, you need to specify a few parameters of the bitmap. You must know in advance the width and height and also the PixelFormat of the buffer.
byte[] buffer = ...;
var width = 100; // for example
var height = 100; // for example
var dpiX = 96d;
var dpiY = 96d;
var pixelFormat = PixelFormats.Pbgra32; // for example
var stride = (width * pixelFormat.BitsPerPixel + 7) / 8;
var bitmap = BitmapSource.Create(width, height, dpiX, dpiY,
pixelFormat, null, buffer, stride);
I ran across this same error, but it was because my array was not getting filled with the actual data. I had an array of bytes that was equal to the length it was supposed to be, but the values were all still 0 - they had not been written to!
My particular issue - and I suspect for others that arrive at this question, as well - was because of the OracleBlob parameter. I didn't think I needed it, and thought I could just do something like:
DataSet ds = new DataSet();
OracleCommand cmd = new OracleCommand(strQuery, conn);
OracleDataAdapter oraAdpt = new OracleDataAdapter(cmd);
oraAdpt.Fill(ds)
if (ds.Tables[0].Rows.Count > 0)
{
byte[] myArray = (bytes)ds.Tables[0]["MY_BLOB_COLUMN"];
}
How wrong I was! To actually get the real bytes in that blob, I needed to actually read that result into an OracleBlob object. Instead of filling a dataset/datatable, I did this:
OracleBlob oBlob = null;
byte[] myArray = null;
OracleCommand cmd = new OracleCommand(strQuery, conn);
OracleDataReader result = cmd.ExecuteReader();
result.Read();
if (result.HasRows)
{
oBlob = result.GetOracleBlob(0);
myArray = new byte[oBlob.Length];
oBlob.Read(array, 0, Convert.ToInt32(myArray.Length));
oBlob.Erase();
oBlob.Close();
oBlob.Dispose();
}
Then, I could take myArray and do this:
if (myArray != null)
{
if (myArray.Length > 0)
{
MyImage.Source = LoadBitmapFromBytes(myArray);
}
}
And my revised LoadBitmapFromBytes function from the other answer:
public static BitmapImage LoadBitmapFromBytes(byte[] bytes)
{
var image = new BitmapImage();
using (var stream = new MemoryStream(bytes))
{
stream.Seek(0, SeekOrigin.Begin);
image.BeginInit();
image.StreamSource = stream;
image.CreateOptions = BitmapCreateOptions.PreservePixelFormat;
image.CacheOption = BitmapCacheOption.OnLoad;
image.UriSource = null;
image.EndInit();
}
return image;
}
Create a MemoryStream from the raw bytes and pass that into your Bitmap constructor.
Like this:
MemoryStream stream = new MemoryStream(bytes);
Bitmap image = new Bitmap(stream);
I want to read the raw binary of a PNG file on a website and store it into a byte[], so far I have something like this:
Uri imageUri = new Uri("http://www.example.com/image.png");
// Create a HttpWebrequest object to the desired URL.
HttpWebRequest imgRequest = (HttpWebRequest)WebRequest.Create(imageUri);
using (HttpWebResponse imgResponse = (HttpWebResponse)imgRequest.GetResponse())
{
using (BinaryReader lxBR = new BinaryReader(imgResponse.GetResponseStream()))
{
using (MemoryStream lxMS = new MemoryStream())
{
lnBuffer = lxBR.ReadBytes(1024);
while (lnBuffer.Length > 0)
{
lxMS.Write(lnBuffer, 0, lnBuffer.Length);
lnBuffer = lxBR.ReadBytes(1024);
}
lnFile = new byte[(int)lxMS.Length];
lxMS.Position = 0;
lxMS.Read(lnFile, 0, lnFile.Length);
}
}
}
but I can't use GetResponse on Silverlight because it is not Asynchronous (I think that's the reason) so instead I should be using BeginGetResponse, but I'm not completely clear on how to go about it. This is what I have so far:
HttpWebResponse imgResponse = (HttpWebResponse)imgRequest.BeginGetResponse(new AsyncCallback(WebComplete), imgRequest);
using (imgResponse)
{
using (BinaryReader lxBR = new BinaryReader(imgResponse.GetResponseStream()))
{
/*Same*/
}
}
and
void WebComplete(IAsyncResult a)
{
HttpWebRequest req = (HttpWebRequest)a.AsyncState;
HttpWebResponse res = (HttpWebResponse)req.EndGetResponse(a);
//...? Do I need something else here?
}
can someone explain me a little bit how to use the BeginGetResponse property and how do I use the AsyncCallback.
Thanks!
Note:
I'm new to silverlight and I've been following tutorials and borrowing from other responses here on StackOverflow:
(stackoverflow responce) what I need to do but not in silverlight
tutorial
WebRequest_in_Silverlight
is this valid Silverlight code?
HttpWebResponse imgResponse = (HttpWebResponse)imgRequest.BeginGetResponse(new AsyncCallback(WebComplete), imgRequest);
Got it working, want to post it here in case anyone needs it.
I need to get this image and then modify it (byte level) Silverlight didn't let me save the image directly to a WriteableBitmap and thus I had to get the image with a WebClient as a stream and then save it to a byte[]
this is how I get the image (I already have the specific Uri):
WebClient wc = new WebClient();
wc.OpenReadCompleted += new OpenReadCompletedEventHandler(wc_OpenReadCompleted);
wc.OpenReadAsync(uri)
so when the image is loaded the wc_OpenReadCompleted method is called and it does something like this:
int lengthInBytes = Convert.ToInt32(e.Result.Length);
BinaryReader br = new BinaryReader(e.Result);
byte[] buffer = new byte[lengthInBytes];
using (br)
{
for (int i = 0; i < lengthInBytes; i++)
{
buffer[i] = br.ReadByte();
}
}
at the end the buffer[] has all the bytes of the image (what I wanted)
I'm sure there are better ways of doing this but this is working for me ! )
note: at some point I need to convert the byte[] to a BitmapImage (that was easier than expected):
//imageInBytes is a byte[]
if (imageInBytes != null)
{
MemoryStream rawBytesStream = new MemoryStream(imageInBytes);
BitmapImage img = new BitmapImage();
img.SetSource(rawBytesStream);
return img;
}
I hope this helps anyone.
Use the OpenReadAsync method of the WebClient object. Attach to the OpenReadCompleted event of the WebClient. Use the Stream provided by the Result property of the event args.
Consider setting AllowReadStreamBuffering, this will fill the entire stream before raising the OpenReadCompleted. In either case its likely you can use this stream to complete you real task rather than coping it into a MemoryStream.
I am trying to find out how to use FJCore to encode a WriteableBitmap to a jpeg. I understand that WriteableBitmap provides the raw pixels but I am not sure how to convert it to the format that FJCore expects for its JpegEncoder method. JpegEncoder has two overloads, one takes a FluxJpeg.Core.Image and the other takes in a DecodedJpeg.
I was trying to create a FluxJpeg.Core.Image but it expects a byte[][,] for the image data. byte[n][x,y] where x is width and y is height but I don't know what n should be.
I thought that n should be 4 since that would correspond to the argb info encoded in each pixel but when I tried that FJCore throws an argument out of range exception. Here is what I tried. Raster is my byte[4][x,y] array.
raster[0][x, y] = (byte)((pixel >> 24) & 0xFF);
raster[1][x, y] = (byte)((pixel >> 16) & 0xFF);
raster[2][x, y] = (byte)((pixel >> 8) & 0xFF);
raster[3][x, y] = (byte)(pixel & 0xFF);
Figured it out! I downloaded FJCore from code.google.com and went through the image class. It only expects the RGB bytes. Here is the function that I wrote. I need the base64 version of the image so that's what my function returns.
private static string GetBase64Jpg(WriteableBitmap bitmap)
{
int width = bitmap.PixelWidth;
int height = bitmap.PixelHeight;
int bands = 3;
byte[][,] raster = new byte[bands][,];
for (int i = 0; i < bands; i++)
{
raster[i] = new byte[width, height];
}
for (int row = 0; row < height; row++)
{
for (int column = 0; column < width; column++)
{
int pixel = bitmap.Pixels[width * row + column];
raster[0][column, row] = (byte)(pixel >> 16);
raster[1][column, row] = (byte)(pixel >> 8);
raster[2][column, row] = (byte)pixel;
}
}
ColorModel model = new ColorModel { colorspace = ColorSpace.RGB };
FluxJpeg.Core.Image img = new FluxJpeg.Core.Image(model, raster);
MemoryStream stream = new MemoryStream();
JpegEncoder encoder = new JpegEncoder(img, 90, stream);
encoder.Encode();
stream.Seek(0, SeekOrigin.Begin);
byte[] binaryData = new Byte[stream.Length];
long bytesRead = stream.Read(binaryData, 0, (int)stream.Length);
string base64String =
System.Convert.ToBase64String(binaryData,
0,
binaryData.Length);
return base64String;
}
This code is fine and it should work. I am using same code to send image stream to server via web service and than regenerate image using these bytes...you can save these bytes to Db also
[WebMethod]
public string SaveImage(string data, string fileName)
{
byte[] imageBytes = System.Convert.FromBase64String(data);
MemoryStream mem = new MemoryStream();
mem.Write(imageBytes, 0, imageBytes.Length);
System.Drawing.Image img = System.Drawing.Image.FromStream(mem);
img.Save("D:\\FinalTest.jpg");
return "Saved !";
}
Sounds like [n] should be the byte-array of the image, I have been looking into encoding WriteableBitmap into a JPEG and found the same library but have not looked into it in detail, but assume this would be the case, will add more later to this answer to see if this works, as I have not have the chance to try it yet. There will be some method to get the bytes of a WritableBitmap in Silverlight I guess as it is possible to save to other types.