I am new to Windows 8 app development. In my app I need to display a GridView with images and title. The image URL and the title I get from the server as a XML data. The images are downloaded from the given URL and stored in a local directory. Now, when an image is downloaded I want to notify the GridView and update the particular image view with the downloaded image. I store the title and the local image URI in an ObservableCollection. The data source of the GridView is bound to this ObservableCollection, so once the XML data is downloaded I am able to update the title through the ObservableCollection. But i don't know how to update the images once they are downloaded.
Assuming that your image is saved in the local data folder (ApplicationData.Current.LocalFolder) - you can create a new BitmapImage this way:
var imagePathInLocalDataFolder = ?
var imageUri = new Uri("ms-appdata:///local/" + imagePathInLocalDataFolder, UriKind.Absolute);
var bitmapImage = new BitmapImage(new Uri(imageUri));
You can then assign the bitmapImage variable value to a property that you bind to an Image.Source - and you should see your image.
Related
I have to set a image on wizard dialogue in swt,classpath load this image but image not displayed properly. In my design create a composit in this composit create a lebel.there after in this lebel I want add an image.After that i will create a runnable jar.This jar will be executed with proper image. In my implementation part i have create a resources (src folder) within src folder and in this resources folder kept image which i need.Please find the below code,
File file = new File("resources/Automatics_Logo.png");
Image image = new Image(Display.getDefault(), file.getPath());
Label lblNewLabel_4 = new Label(composite, SWT.NONE);
lblNewLabel_4.setImage(SWTResourceManager.getImage(CheckSystemConfigurationAndInstallation.class,image.toString()));
Image imgSWT=null; // Image class is the SWT Image class
ImageDescriptor imgDesc=null;
java.net.URL imgURL = IntroductionPage.class.getResource("/Automatics_Logo.png");
if (imgURL != null) {
imgDesc = ImageDescriptor.createFromURL(imgURL);
imgSWT = imgDesc.createImage();
I have a database program that stores images to the SQL DB and reads them back to be displayed in a WPF application. if i use Jpeg images it works fine, but if i use PNG images, which i wanted to use to try and keep the transparency ( which disappears anyway when stored ) most of the images come back corrupt.
this is the image that has been selected
i then save it to the db, and add the image the listview
then if i close the application and reload it, it pulls the image back from the db, you can see that it is corrupt in the listview
and then when i select it, the image control also shows the corrupted image
i am storing the image in code using a BitmapImage object, and use this to set the image.source, and also convert this to a byte[] for storing into the image field in the database.
i convert the bitmapimage to a Byte[] with the following line
command.Parameters.AddWithValue("#Image", ImageToByteArray(productImage.ProductImage));
and these are the functions to convert to and from a bitmapimage
private static BitmapImage BuildImage(byte[] image)
{
var bitmap = new BitmapImage();
bitmap.BeginInit();
MemoryStream mem = new MemoryStream(image);
bitmap.StreamSource = mem;
bitmap.CacheOption = BitmapCacheOption.OnLoad;
bitmap.EndInit();
//bitmap.Freeze();
return bitmap;
}
private static byte[] ImageToByteArray(BitmapImage image)
{
byte[] data;
JpegBitmapEncoder encoder = new JpegBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(image));
using (MemoryStream ms = new MemoryStream())
{
encoder.Save(ms);
data = ms.ToArray();
}
return data;
}
works fine with Jpegs, but then i have the white background to the images.
any help would be much appreciated.
"JpegBitmapEncoder" is a large clue. Surely you'd want "PNGBitmapEncoder"...?
As personal preference I would change your SQL data column to varbinary(MAX) and use stream and BinaryReader objects to upload the file.
However I think your issue is you are not using PngBitmapEncoder for the PNG you are using the JpegBitmapEncoder irrespective of filetype.
Hope this helps.
I am trying to change the Background of a button to an image source. I want to load that image in memory when we navigate to the page so that it doesn't flicker the first time it shows.
On Windows Phone, I was able to create the image source as such:
StreamResourceInfo resourceInfo = Application.GetResourceStream(uri);
BitmapImage bitmapSource = new BitmapImage();
// Avoid flicker by not delay-loading.
bitmapSource.CreateOptions = BitmapCreateOptions.None;
bitmapSource.SetSource(resourceInfo.Stream);
imageSource = bitmapSource;
I tried something similar in my Windows 8 Store app:
BitmapImage bitmapSource = new BitmapImage();
bitmapSource.CreateOptions = BitmapCreateOptions.None;
bitmapSource.UriSource = uri;
imageSource = bitmapSource;
but the same problem occurs. The button already has a different image as the Background, and on a certain event I would like it to change to the new background. But when I change the source, a noticeable flicker is observed. I'm assuming this is because the image is not yet in memory, as the issue goes away the second time the image source is modified.
Anyone know a solution? I need to somehow force the loading of this image.
Thanks!
If you use the SetSourceAsync method on the BitmapImage and await it before you attach it to the image source you should not see the flicker:-
// Ensure the stream is disposed once the image is loaded
using (IRandomAccessStream fileStream = await file.OpenAsync(Windows.Storage.FileAccessMode.Read))
{
// Set the image source to the selected bitmap
BitmapImage bitmapImage = new BitmapImage();
await bitmapImage.SetSourceAsync(fileStream);
imageSource = bitmapImage;
}
The MSDN docs have some more info on this
Thanks Ross, but what I ended up doing instead is I preloaded the half dozen or so bitmaps I needed by using similar code to what you had above, except from resource of course. I did this asynchronously when the page loaded, and then when I set the ImageSource on the button background, I used the already preloaded bitmaps. That way I know I'm not allocated a new chunk of memory for every instance of the bitmap.
My app retrieves file content from remote server. File can be image or text. When the file is image it returns some string like this:
????\bNExif\0\0MM\0*\0\0\0\b\0\a\0.... and so on. As I understand it's an image but in other format (binary?).
So how can I convert that string to an image and set it to control as source?
Thanks.
I think you can do something like this:
MemoryStream ms = new MemoryStream(bytes);
BitmapImage bi = new BitmapImage();
bi.SetSource(ms);
Then if you have an Image element in XAML, say XamlImage:
XamlImage.Source = bi;
I'm building a Win8/WinJS app that loads pictures from the local pictures library. Everything is generally working fine for loading valid images and displaying them in a list view.
Now I need to detect corrupt images and disable parts of the app for those images.
For example, open a text file and enter some text in it. Save the file as .jpg, which is obviously not going to be a valid jpg image. My app still loads the file because of the .jpg name, but now I need to disable certain parts of the app because the image is corrupt.
Is there a way I can check to see if a given image that I've loaded is a valid image file? To check if it's corrupt or not?
I'm using standard WinRT / WinJS objects like StorageFile, Windows.Storage.Search related objects, etc, to load up my image list based on searches for file types.
I don't need to filter out corrupt images from the search results. I just need to be able to tell if an image is corrupt after someone selects it in a ListView.
One possible solution would be to check the image's width and height properties to determine whether it is valid or not.
Yeah, the contentType property will return whatever the file extension is. The best way I can find it to look at the image properties:
file.properties.getImagePropertiesAsync()
.done(function(imageProps) {
if(imageProps.width === 0 && imageProps.height === 0) {
// I'm probably? likely? invalid.
});
where SelectImagePlaceholder is an Image Control.. =)
StorageFile file;
using (IRandomAccessStream fileStream = await file.OpenAsync(Windows.Storage.FileAccessMode.Read))
{
try
{
// Set the image source to the selected bitmap
BitmapImage bitmapImage = new BitmapImage();
await bitmapImage.SetSourceAsync(fileStream);
SelectImagePlaceholder.Source = bitmapImage;
//SelectImagePlaceholder.HorizontalAlignment = HorizontalAlignment.Center;
//SelectImagePlaceholder.Stretch = Stretch.None;
this.SelectImagePlaceholder.DataContext = file;
_curMedia = file;
}
catch (Exception ex)
{
//code Handle the corrupted or invalid image
}
}