Can anyone point me to a resource on how to "fade in" an image on load in silverlight? Basically I have a listbox of items that are returned from a web service and some times the images take a little longer to load, so I wanted to fade them in as they download. I read that I might need a storyboard for this effect. Is this the best route or are there alternatives?
I'm not aware of any alternatives. The StoryBoard is the best route. You could just animate the Opacity of the image from 0 to 100.
Put the Storyboard in the resources for the UserControl () or in the App.xaml.
Then in your OnOpened event (as you mentioned in the comment):
protected void OnOpened(object sender, EventArgs e)
{
// params might be incorrect
this.fadeInStoryBoard.Stop();
// your image controls will need x:names set
this.fadeInAnimation.SetValue(Storyboard.TargetNameProperty, ((Image)sender).Name);
this.fadeInStoryBoard.Start();
}
The example storyboard is from:
http://www.codeproject.com/KB/silverlight/AgDynAnimations.aspx
and starting the storyboard: http://blogs.msdn.com/b/silverlight_sdk/archive/2008/03/26/target-multiple-objects-properties-with-one-animation-silverlight.aspx
Here's a utility function to perform the task
private void FadeIn(UIElement uilelement)
{
uilelement.Opacity = 0.0;
uilelement.Visibility = Visibility = Visibility.Visible;
var timeline = new DoubleAnimation() { To = 1.0, Duration =TimeSpan.FromSeconds(3.0) };
Storyboard.SetTarget(timeline, uilelement);
Storyboard.SetTargetProperty(timeline, new PropertyPath(UIElement.OpacityProperty));
var sb = new Storyboard();
sb.Children.Add(timeline);
sb.Begin();
}
function void image1_Opened(object sender, EventArgs e)
{
FadeIn(sender as Image);
}
You should set the Image to Collapsed, or set its initial Opacity to 0.
<Image Source="{Binding ImagePath}"
Name="image1"
Visibility="Collapsed"
ImageOpened="image1_ImageOpened" />
Related
I'm trying to create a snapshot/image/bitmap of an element that I can display as content in another control.
It seems the suggested way to do this is with a VisualBrush, but I can't seem to get it to create a snapshot of the current value and keep that state. When you alter the original source, the changes are applied to all the "copies" that have been made too.
I have made a simple example to show what I mean.
What I want is for the items added to the stackpanel to have the opacity that was set when they were cloned. But instead, changing the opacity on the source changes all "clones".
<StackPanel Width="200" x:Name="sp">
<DockPanel>
<Button Content="Clone"
Click="OnCloneButtonClick" />
<TextBlock Text="Value" x:Name="tb" Background="Red" />
</DockPanel>
</StackPanel>
private void OnCloneButtonClick(object sender, RoutedEventArgs e)
{
tb.Opacity -= 0.1;
var brush = new VisualBrush(tb).CloneCurrentValue();
sp.Children.Add(new Border() { Background = brush, Width = tb.ActualWidth, Height = tb.ActualHeight });
}
I am afraid the visual elements aren't cloned when you call CloneCurrentValue().
You will have to clone the element yourself, for example by serializing the element to XAML and then deserialize it back using the XamlWriter.Save and XamlReader.Parse methods respectively:
private void OnCloneButtonClick(object sender, RoutedEventArgs e)
{
tb.Opacity -= 0.1;
var brush = new VisualBrush(Clone(tb));
sp.Children.Add(new Border() { Background = brush, Width = tb.ActualWidth, Height = tb.ActualHeight });
}
private static Visual Clone(Visual visual)
{
string xaml = XamlWriter.Save(visual);
return (Visual)XamlReader.Parse(xaml);
}
Using WPF: A Simple Color Picker With Preview, Sacha Barber, 18 Apr 2012 ,
I created a custom control from it:
public class ColorCustomControl : Control
{....}
It is then used as:
<Menu....>
<MenuItem.....>
<pn:ColorCustomControl/>
</MenuItem>
</Menu>
This yields the following picture when the Brushes MenuItem is selected:
Selection of any item in the opened Brushes submenu results in the appropriate action being taken with the Brushes submenu REMAINING OPEN. This is the effect I want.
However, as shown below, selection of any of the three swatches results in a quick flicker of the new swatch -- it replaces the color pattern to the left of "Preview"--followed immediately by closure of the Brushes submenu.
If the Brushes menuitem is again chosen, the most recently selected swatch correctly appears.
I have tried all preview events (i.e., keyboard lost focus, left mouse down, etc.), to try stopping closure of the submenu when a swatch is chosen. Nothing I have found will stop the popup from closing.
How can closure of the Brushes submenu be prevented when selecting a swatch from the visual?
(I strongly suspect that redrawing of the visual, as in InvalidateVisual() when a new swatch image is selected, is forcing closure of the submenu).
Any ideas anybody?
TIA
My suggestion is to stop events propagation from your user control. So in your ColorCustomControl class first of all add a property (it can be a dependency one too if you need):
private bool propagateEvents = true;
public bool PropagateEvents
{
get
{
return propagateEvents;
}
set
{
propagateEvents = value;
}
}
Then add e.Handled = !PropagateEvents; at the end of every mouse event handler; in the end add a Swatch_MouseLeftButtonUp method (it has to handle the event raised by ImgSqaure1, ImgSqaure2 and ImgCircle1).
The result will be:
private void Swatch_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
Image img = (sender as Image);
ColorImage.Source = img.Source;
e.Handled = !PropagateEvents;
}
private void Swatch_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
e.Handled = !PropagateEvents;
}
private void CanvImage_MouseDown(object sender, MouseButtonEventArgs e)
{
IsMouseDown = true;
e.Handled = !PropagateEvents;
}
private void CanvImage_MouseUp(object sender, MouseButtonEventArgs e)
{
IsMouseDown = false;
e.Handled = !PropagateEvents;
}
and in the user control XAML:
<Image x:Name="ImgSqaure1"
Height="20" Width="20"
Source="Images/ColorSwatchSquare1.png"
Margin="45,0,0,0"
ToolTip="Square swatch1"
MouseLeftButtonDown="Swatch_MouseLeftButtonDown"
MouseLeftButtonUp="Swatch_MouseLeftButtonUp"/>
<Image x:Name="ImgSqaure2"
Height="20" Width="20"
Source="Images/ColorSwatchSquare2.png" Margin="5,0,0,0"
ToolTip="Square swatch2"
MouseLeftButtonDown="Swatch_MouseLeftButtonDown"
MouseLeftButtonUp="Swatch_MouseLeftButtonUp"/>
<Image x:Name="ImgCircle1" Height="20" Width="20"
Source="Images/ColorSwatchCircle.png" Margin="5,0,0,0"
ToolTip="Circle swatch1"
MouseLeftButtonDown="Swatch_MouseLeftButtonDown"
MouseLeftButtonUp="Swatch_MouseLeftButtonUp" />
Now all you have to do is set the PropagateEvents property in your menu:
<Menu....>
<MenuItem.....>
<pn:ColorCustomControl PropagateEvents="False" />
</MenuItem>
</Menu>
I hope it can help you.
I have large treeview full of textboxes, each with tooltip containing a unique image. The image is stored in a property as a bytearray and I bind to it. Every time a new tooltip is displayed more memory is used.
I will be scaling the image, but that doesn't address the root of the problem. If there a way to free the memory used after the tooltip is no longer displayed?
<TextBlock.ToolTip>
<StackPanel>
<Image MaxWidth="650"
MaxHeight="400"
Source="{Binding ImageAsByteArray}"/>
<TextBlock Text="{Binding FilePath, StringFormat='Full Path: {0}'}" />
</StackPanel>
</TextBlock.ToolTip>
The tooltip can be set to any framework element, so could dynamically create this as an object behind the scenes:
<TextBlock ToolTip={Binding ToolTip} />
Then your view model or code behind could dynamically create this object and handle the loaded/unloaded event to capture when the tooltip displays.
I've done it below with a canvas is case you want to add other children besides the image:
var tooltipCanvas = new Canvas();
var img = new Image();
tooltipCanvas.Children.Add(img);
tooltipCanvas.Width = 500;
tooltipCanvas.Height = 500;
tooltipCanvas.Loaded += Tooltip_Loaded;
tooltipCanvas.Unloaded += Tooltip_Unloaded;
Then you could populate the image source just for the time the image is shown using the loaded and unloaded event handlers:
private void Tooltip_Loaded(object sender, RoutedEventArgs e)
{
var canvas = sender as Canvas;
var img = canvas.Children[0] as Image;
img.Source = /* get your image bytes */;
}
private void Tooltip_Unloaded(object sender, RoutedEventArgs e)
{
var canvas = sender as Canvas;
var img = canvas.Children[0] as Image;
img.Source = null;
}
I'm using a progress bar for loading an image in an application for Windows Phone 7.
bitmapImage.DownloadProgress += new EventHandler<DownloadProgressEventArgs (bitmapImage_DownloadProgress);
void bitmapImage_DownloadProgress(object sender, DownloadProgressEventArgs e)
{
progressBar.Value = e.Progress;
}
XAML file:
<ProgressBar x:Name="progressBar" IsIndeterminate="True" Width="300" Height="30" Style="{StaticResource PerformanceProgressBar}" />
I'd like to know the best way to make the progress bar disappear once the image is loaded.
Use the events ImageOpened which triggers when image has been loaded successfully and ImageFailed which triggers if image failed to download.
bitmapImage.ImageOpened += new EventHandler<RoutedEventArgs>(bi_ImageOpened);
bitmapImage.ImageFailed += new EventHandler<ExceptionRoutedEventArgs>(bi_ImageFailed);
void bi_ImageFailed(object sender, ExceptionRoutedEventArgs e)
{
MessageBox.Show("Download of image failed");
progressBar.Visibility = Visibility.Collapsed;
}
void bi_ImageOpened(object sender, RoutedEventArgs e)
{
progressBar.Visibility = Visibility.Collapsed;
}
Simply hide it via the Visibility property
progressBar.Visibility = Visibility.Collapsed
I have a Silverlight application in which I'm not using XAML. I have a basic application with the following code in Application_Startup:
private void Application_Startup(object sender, StartupEventArgs e)
{
Grid g = new Grid();
g.Children.Add(new Image { Source = new System.Windows.Media.Imaging.BitmapImage(new Uri("http://sstatic.net/so/img/sprites.png", UriKind.Absolute)) });
this.RootVisual = g;
}
This code will not render the specified image. If however, the App.Xaml file is modified to define the RootVisual in the Xaml the following works:
xaml:
<Application.RootVisual>
<Grid>
</Grid>
</Application.RootVisual>
code:
private void Application_Startup(object sender, StartupEventArgs e)
{
((Grid)this.RootVisual).Children.Add(new Image { Source = new System.Windows.Media.Imaging.BitmapImage(new Uri("http://sstatic.net/so/img/sprites.png", UriKind.Absolute)) });
}
I don't see why one would work and the other not. I have the same behavior using a UserControl as well (using Content instead of Childern of course).
From what I understand, there should be not XAML requirement. Is there something I'm missing?
The difference is in the first case you are setting the RootVisual to be a Grid, but in the second your grid is a child element.
On the MSDN page for the RootVisual property it shows the following example:
this.RootVisual = new Page();
so if you create a Page and then add your Grid to that page it should work.
Page page = new Page();
page.Content = g;
this.RootVisual = page;