Out of memory Exception on Listview with images and inkcanvas UWP

Question

my idea is to create a listview with images, over each image I would like to insert a InkCanvas. I tried two ways and both have problems.

First way.

I created the listview with its DataTemplate:

<DataTemplate x:Name="ListViewItemTemplate">
        <Grid>
           <Image></Image>
           <InkCanvas></InkCanvas>
        </Grid>
</DataTemplate>

<ItemsPanelTemplate x:Name="ListItemsPanelTemplate">
        <VirtualizingStackPanel Orientation="Vertical">
            <VirtualizingStackPanel.ChildrenTransitions>
                <TransitionCollection/>
            </VirtualizingStackPanel.ChildrenTransitions>
        </VirtualizingStackPanel>
</ItemsPanelTemplate>

<ListView x:Name="list" 
    ItemTemplate="{StaticResource ListViewItemTemplate}"
    ItemsPanel="{StaticResource ListItemsPanelTemplate}">
</ListView>

c#:

 List<Image> pages = new List<Image>();
    list.ItemsSource = pages;

In this way, the listview uses virtualization, when I write in a inkview, the stroke is copied every 5 inkview. It's not good.

If I remove the virtualization:

<ItemsPanelTemplate x:Name="ListItemsPanelTemplate">
        <StackPanel Orientation="Vertical"/>
</ItemsPanelTemplate>

It occurs the problem of the second way. Written below.

Second way:

I created a usercontrol PageFormat for the DataTemplate like this:

<UserControl>
<Grid Background="White">
    <Image x:Name="image"></Image>
    <InkCanvas x:Name="ink" ></InkCanvas>
</Grid>
</UserControl>

<ListView x:Name="list" ></ListView>

c#:

List<PageFormat> pages= new List<PageFormat>();
list.ItemsSource = pages;

In this way I have the following problem:like in this question

When I create more than 125 InkCanvas I have a memory problem. I prefer the second way because I can play with the formatting of the page directly in a usercontrol, but I can not solve these problems.

I would like to solve the problem of generating InkCanvas the System.OutOfMemoryException error. How can I solve it? Thanks so much.

instead of listview? however I think that reoccurs the problem of memory for more than 125 InkCanvas. — Andrea485, Jan 19 '17 at 21:03
I only posted the elements without property, the application works, I view images, for less than 125 images has no problems, problems occur with too many images because it can not create more than 125 InkCanvas, and cause out of memory exception. — Andrea485, Jan 19 '17 at 21:19
Nope there is no memory leak only an out of memory exception due to many inkcanvas. — Andrea485, Jan 19 '17 at 22:56

aybe · Answer 1 · 2017-01-19T22:17:42.547

If you are 100% sure that InkCanvas is the cause of out of memory exceptions, you could do the following pseudo-system:

when a user is not editing an item, it should be persisted to disk/memory and a bitmap rendered and presented out of it.
when a user starts editing an item, de-serialize its data and realize it as an InkCanvas

i.e. use less resource-intensive types wherever it is appropriate

EDIT

Here's the solution to the fact that rendering an InkCanvas to a RenderTargetBitmap will produce a blank image:

https://mtaulty.com/2016/02/16/windows-10-uwp-inkcanvas-and-rendertargetbitmap/

(requires Win2D package)

could be a solution, I'll try. – Andrea485 Jan 19 '17 at 21:27 — Andrea485, Jan 19 '17 at 21:27

Out of memory Exception on Listview with images and inkcanvas UWP

1 Answers1