WPF has an ImageSource which has a BitmapMetadata.
However, the Metadata property is read only an the BitmapMetadata is frozen.
So I can I modify the metadata of an image?
Unfortunately the WPF imaging API doesn't allow you to modify the image metadata... However, you can still do it with GDI+ (System.Drawing)
Found the answer:
var frame = ...;
BitmapMetadata newMetadata = ...;
var newFrame = BitmapFrame.Create(frame, frame.Thumbnail, newMetadata, frame.ColorContexts);
var encoder = new JpegBitmapEncoder();
encoder.Frames.Add(newFrame);
Related
My application shows a large number of image thumbnails at once. Currently, I am keeping all full size images in memory, and simply scaling the image in the UI to create the thumbnail. However, I'd rather just keep small thumbnails in memory, and only load the fullsize images when necessary.
I thought this would be easy enough, but the thumbnails I'm generating are terribly blurry compared to just scaling the fullsize image in the UI.
The images are byte arrays with no header information. I know the size and format ahead of time, so I can use BitmapSource.Create to create an ImageSource.
//This image source, when bound to the UI and scaled down creates a nice looking thumbnail
var imageSource = BitmapSource.Create(
imageWidth,
imageHeight,
dpiXDirection,
dpiYDirection,
format,
palette,
byteArray,
stride);
using (var ms = new MemoryStream())
{
PngBitmapEncoder encoder = new PngBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(imageSource);
encoder.Save(ms);
var bi = new BitmapImage();
bi.BeginInit();
bi.CacheOption = BitmapCacheOption.OnLoad;
//I can't just create a MemoryStream from the original byte array because there is no header info and it doesn't know how to decode the image!
bi.StreamSource = ms;
bi.DecodePixelWidth = 60;
bi.EndInit();
//This thumbnail is blurry!!!
Thumbnail = bi;
}
I'm guessing its blurry since I'm converting it to png first, but when I use the BmpBitmapEncoder I get that "No imaging component available" error. In this case my image is Gray8, but I'm not sure why the PngEncoder can figure it out but the BmpEncoder can't.
Surely there must be someway to create a thumbnail from the original ImageSource without having to encode it to a bitmap format first? I wish BitmapSource.Create just let you specify a decode width/height like the BitmapImage class does.
EDIT
The final answer is to use a TransformBitmap with a WriteableBitmap to create the thumbnail and eliminate the original, full-size image.
var imageSource = BitmapSource.Create(...raw bytes and stuff...);
var width = 100d;
var scale = width / imageSource.PixelWidth;
WriteableBitmap writable = new WriteableBitmap(new TransformedBitmap(imageSource, new ScaleTransform(scale, scale)));
writable.Freeze();
Thumbnail = writable;
You should be able to create a TransformedBitmap from the original one:
var bitmap = BitmapSource.Create(...);
var width = 60d;
var scale = width / bitmap.PixelWidth;
var transform = new ScaleTransform(scale, scale);
var thumbnail = new TransformedBitmap(bitmap, transform);
In order to get ultimately rid of the original bitmap, you could create a WriteableBitmap from the TransformedBitmap:
var thumbnail = new WriteableBitmap(new TransformedBitmap(bitmap, transform));
I have a WPF project, which we using some WindowsForm control(PivotTable from OWC, Office Web Component). However, since the PivotTable doesn't support print very well, the only way we can think of is to print the image file PivotTable exports(another way is to print from exported Excel file, but we want to avoid it since it is not guaranteed that Excel is installed on the machine).
We already have one print project, which will print WPF ElementFramework nicely. So I want to use that piece of code. Now my question is: how I can generate a FrameworkElement out of a BitmapImage from code. Since this FrameworkElement is purely for printing, so I guess I must create it from the code, probably assign a parent to it, not show it on the screen, and after the printing destroy the FrameworkElement so that ultimately I can delete the temp BitmapImage file.
So this is beyond my knowledge. I don't even know whether that's a proper way: create a UI element for some non-UI related work? Any advice on that? Thanks!
You should load the temp image file's bytes into memory and create a Image from those bytes.
Your Image will not use the temp file directly and you can delete it immediately after reading the bytes, the rest is GarbageCollector's job. Here is a function to create your BitmapImage from bytes:
public static BitmapImage GetImageFromByteArray(byte[] rawImageBytes)
{
BitmapImage imageSource = null;
try
{
using (MemoryStream stream = new MemoryStream(rawImageBytes))
{
stream.Seek(0, SeekOrigin.Begin);
BitmapImage bi = new BitmapImage();
bi.BeginInit();
bi.CacheOption = BitmapCacheOption.OnLoad;
bi.StreamSource = stream;
bi.EndInit();
imageSource = bi;
}
}
catch (System.Exception)
{
}
return imageSource;
}
And use it like this:
testImage.Source = GetImageFromByteArray(rawImageBytes);
How to assign a picture Image.Source: Image.Source = "Images \ 1.bmp" - does not work (you can not assign a picture)
Image myImage3 = new Image();
BitmapImage bi3 = new BitmapImage();
bi3.BeginInit();
bi3.UriSource = new Uri("smiley_stackpanel.PNG", UriKind.Relative);
bi3.EndInit();
myImage3.Stretch = Stretch.Fill;
myImage3.Source = bi3;
As mentioned above easily found here
Refer to Pack URIs in WPF
Don't forget to set the Build Action for '1.bmp' to Resource
The Image.Source page at MSDN http://msdn.microsoft.com/en-us/library/system.windows.controls.image.source.aspx has an example. You need to assign an ImageSource, not a string. (but of course see Pack URIs in above post)
What I got is something like a screenshot making application. (managed to serialize, thank god!!!) When a button is clicked a screenshot is taken by accessing a handling classe's method. now the tricky part is that the class has another method for operating with the above said result, in such a manner than when the respective handling method is called, a window is created(shown) and the bitmap image should go into a display container in that window. The problem is that so far, I've noticed that in WPF the image control's source cannot be attribuited to a variable which stores the image. How can i display the image stored in that variable without having to save it first,get uri,etc. ?
You need to create an image from a memory stream, this has been well documented by many people. Here are two links that may get you started:
http://forums.silverlight.net/forums/p/44637/166282.aspx
http://www.wpftutorial.net/Images.html
thanks for the links slugster. Here's how I did it:
MemoryStream ms = new MemoryStream();
sBmp = gBmp; //note: gBmp is a variable that stores the captured image and passes it on to the method that uses sBMP as a distribuitor of the variable holding the captured image data
//variable that holds image
sBmp.Save(ms,ImageFormat.Bmp);
//my buffer byte
byte[] buffer = ms.GetBuffer();
//Create new MemoryStream that has the contents of buffer
MemoryStream bufferPasser = new MemoryStream(buffer);
//Creates a window with parents classthatholdsthismethod and null
Edit childEdit = new Edit(this, null);
childEdit.Show();
//I create a new BitmapImage to work with
BitmapImage bitmap = new BitmapImage();
bitmap.BeginInit();
bitmap.StreamSource = bufferPasser;
bitmap.EndInit();
//I set the source of the image control type as the new BitmapImage created earlier.
childEdit.imgImageCanvas.Source = bitmap;
childEdit.Activate();
I've basically combined what I had found on those pages with some info I found on how to pass on a bmp to a memstream. I got this to work 100% :)
What I am trying to do is so simple but I am having a hard time making it work. I saw some posts along the same lines but I still have questions.
I have a MenuItem object called mnuA. All I want is set the icon property programatically in C#. I have tried the following
a) mnuA.Icon = new BitmapImage{UriSource = new Uri(#"c:\icons\A.png")};
Results: Instead of showing the actual icon, I get the class name (System.Windows.Media.Imaging.BitmapImage)
b) mnuA.Icon = new BitmapImage(new Uri(#"c:\icons\A.png"));
Results: Instead of showing the actual icon, I get the path of the image (file:///c:/icons/A.png)
What am I doing wrong? Do I really need a converter class for something simple like this?
Try this:
Image img = new Image();
img.Source = new BitmapImage(new Uri(#"c:\icons\A.png"));
mnuA.Icon = img;
Might be a long shot, but try something like:
Uri u = new Uri(...); mnuA.Icon = new
BitmapImage(u);
What it seems its happening is that your icon is getting converted to a string.