Re: How to load only needed images? [modified] - WPF Discussion Boards

13-Mar-09 8:48

I wonder why data access is a security risk that they are not allowed in partial-trust.

Eslam Afifi

Double Animation Hell

emptythetill13-Mar-09 2:55

Re: Double Animation Hell

13-Mar-09 2:55

Hello.

In attempting to convert from Flash to WPF I'm going through the stages of re-working stuff which is easy to do in AS3. This latest example is proving a nightmare. So, imagine you have a set of squares...

[IMG]http://img22.imageshack.us/img22/7858/grid.png[/IMG]

You click at a random place on the screen, the 'lead' square moves there and the rest catch up one afte the other. The only way I can seem to achieve this in WPF is to use three DoubleAnimations on every square, X, Y and Angle. But this leaves me with shed loads of code instead of the 2-3 lines I'd use in AS3 (it does run much quicker though). So my question is to do this simple thing in WPF, wanting a nice smooth transition and wanting to set the duration etc how would you go about it? I thought about applying a for loop and running each one through, would that be a good way?

Regards, E.

Insincere Dave13-Mar-09 8:06

Insincere Dave

13-Mar-09 8:06

Animations are rather verbose but it would be quite simple to write some helper functions to do common scenarios. These tutorials tutorials might be of some use if your familar with flash, they are for silverlight but the code should be simpler in WPF as you could use a timer or CompositionTarget instead of an empty storyboard. It shouldn't be that hard to replicate the AS3 code using procedural animation.

Re: Double Animation Hell

emptythetill14-Mar-09 5:21

How to load only needed images?

14-Mar-09 5:21

Hello. Cheers for that, and thanks for always answering my questions. Smile | :)

S.a.n.4.e.s12-Mar-09 7:35

12-Mar-09 7:35

Hi everybody! I'm a kind of newbie in WPF and I have an app, that shows in a ListBox images from some directory. I'm using recycling option and a converter to minimize images to 100 width. This realy decrease memory usage, but the case is that app's start takes some time (up to 2 minutes on 2000 5mp images). And this time depends on quantity of images linearly.. I think, that's because of app has to load all images in cash, and i want to perform quick start and then to load images needed. Also, when app starts memory goes up to 250 Mb on ~300 5mp images, and on loaded memory decreases to 70-80 Mb and stays steady. Any ideas?

Eslam Afifi12-Mar-09 12:27

12-Mar-09 12:27

I have not done any serious WPF yet so I didn't run into such situations. But I think this may solve your problem.

<ListBox VirtualizingStackPanel.IsVirtualizing="True" />

Please tell me if it works.

Eslam Afifi

S.a.n.4.e.s12-Mar-09 19:18

Re: How to load only needed images? [modified]

12-Mar-09 19:18

It set to true all the time, but unfortunatly it doesn't solve the problem.

Eslam Afifi13-Mar-09 2:53

13-Mar-09 2:53

I've just got online and read Luc Pattyn's replies. I'd like to add to his/her advice using the MVVM pattern and store the thumbnails in the Model-View, or maybe in the Model itself. Make the converter checks if the thumbnail exists or not so you use the cached thumbnail or create and store it. You can keep the thumbnails in memory or on disk, whatever is best for your situation. All that while keeping the ListBox virtualizing.

Eslam Afifi

modified on Saturday, March 14, 2009 8:08 AM

Luc Pattyn12-Mar-09 13:29

Luc Pattyn

12-Mar-09 13:29

Hi,

this problem is not specific to WPF. There generally are two remedies:
1. only load what is really necessary; having controls that support a "virtual" mode makes that easier.
2. compute "thumbnails" once, and store them on disk, together with the actual images. Don't worry about disk space, they could well be 100 times smaller than the originals.

Smile | :)

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S.a.n.4.e.s12-Mar-09 20:30

12-Mar-09 20:30

I'm using controls, that support "virtual" mode, and i think it work on scrolling, but i interest in faster startup. I don't know why it starts so long, and i assume that all the images are cached on load. Maybe i'm wrong, but i don't know another reason. That's why i need help. If it matter's, i can show code.

Luc Pattyn13-Mar-09 2:14

Luc Pattyn

13-Mar-09 2:14

Hi,

improving the performance is similar to debugging, so gather the facts, analyze, formulate an hypothesis, verify, fix, and iterate.

These are the first steps I would take:
- install logging code, basically a "public static void log(string)" method that saves a string to a log file;
- set up a StopWatch, so each log message automatically gets prefixed with the elapsed time with millisecond resolution
- sprinkle log statements in the relevant parts of the app.
- now have a trial run: startup, stop, look at the log file; any time gap exceeding say 100 msec needs either more log statements, and if that is not possible, is a hotspot in need of fixing. It might be a Thread.Sleep() you forgot to remove, a first database access (move to another thread?), a first network access, etc.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Re: How to load only needed images? [modified]

Luc Pattyn13-Mar-09 2:19

Luc Pattyn

13-Mar-09 2:19

S.a.n.4.e.s wrote:
i assume that all the images are cached on load

not sure what you mean.

S.a.n.4.e.s wrote:
If it matter's, i can show code

it might be useful, *after* you tried to localize and fix the slow parts.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

S.a.n.4.e.s14-Mar-09 0:10

Storing Signature in sql server database

14-Mar-09 0:10

<blockquote class="FQ"><div class="FQA">Luc Pattyn wrote:</div> S.a.n.4.e.s wrote:
i assume that all the images are cached on load

not sure what you mean.</blockquote>

I mean, that all the collection of images, binded to ListView, are loading on startup. I use a single thread, don't use network or database, i simple get *.jpg files from some directory on one of my disks.

There's my code.
XAML:
<pre>
<usercontrol.resources>
<objectdataprovider x:name="PhotosODP" x:key="MyPhotos" objecttype="{x:Type l:PhotoList}" xmlns:x="#unknown" />
<l:uritoimageconverter x:key="LocalUriToImageConverter" xmlns:x="#unknown" xmlns:l="#unknown" />
<DataTemplate DataType="{x:Type l:Photo}">
<Grid VirtualizingStackPanel.IsVirtualizing="True" VirtualizingStackPanel.VirtualizationMode="Recycling">
<Border Background="#FF562100" Padding="4" BorderThickness="1">
<StackPanel Width="{Binding ElementName=Zoomer, Path=Value}" Margin="5" VirtualizingStackPanel.IsVirtualizing="True" VirtualizingStackPanel.VirtualizationMode="Recycling">
<Image Source="{Binding Source, Converter={StaticResource LocalUriToImageConverter}}" VirtualizingStackPanel.IsVirtualizing="True" VirtualizingStackPanel.VirtualizationMode="Recycling"/>
<Label Foreground="White" Content="{Binding FileName}" />
</StackPanel>
</Border>
</Grid>
</DataTemplate>
</usercontrol.resources>
</pre>

And C# class, that makes a collection:
<pre>
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Media.Imaging;

namespace Components
{
public class Photo
{
public Photo(string path)
{
_source = path;
_name = path.Substring(path.LastIndexOf("\\") + 1);
}

public override string ToString()
{
return Source;
}

private string _source;
public string Source { get { return _source; } }
//my
private string _name;
public string FileName { get { return _name; } }
//

}

public class PhotoList : ObservableCollection<photo>
{
public PhotoList() { }

public PhotoList(string path) : this(new DirectoryInfo(path)) { }

public PhotoList(DirectoryInfo directory)
{
_directory = directory;
Update();
}

public string Path
{
set
{
_directory = new DirectoryInfo(value);
Update();
}
get { return _directory.FullName; }
}

public DirectoryInfo Directory
{
set
{
_directory = value;
Update();
}
get { return _directory; }
}

private void Update()
{
foreach (FileInfo f in _directory.GetFiles("*.jpg"))
{
Add(new Photo(f.FullName));
}
}

DirectoryInfo _directory;
}

}
</photo></pre>
And an event of an app, on which load of images starts:
<pre>
private void UserControl_Initialized(object sender, EventArgs e)
{
photos = (PhotoList)(this.Resources["MyPhotos"] as ObjectDataProvider).Data;
photos.Path = path;
}
</pre>

modified on Saturday, March 14, 2009 6:57 AM

vsaratkar12-Mar-09 5:45

vsaratkar

12-Mar-09 5:45

Hi,

I am using InkCanvas control for signature. Can anyone tell me how to store these signatures in sql server DB?

Vsaratkar

Eslam Afifi12-Mar-09 13:00

12-Mar-09 13:00

Save the strokes to a memory stream

var memoryStream = new System.IO.MemoryStream();
inkCanvas.Strokes.Save(memoryStream); // you may want to add a second parameter = true
to compress the data

then store the data of the memory stream in your database as an appropriate binary type.

to load the data to an InkCanvans from a memory stream

inkCanvas1.Strokes = new StrokeCollection(memoryStream); // make sure that the position of
memoryStream = 0

Eslam Afifi

vsaratkar13-Mar-09 2:13

vsaratkar

13-Mar-09 2:13

Thanks Eslam!!!!!

Eslam Afifi13-Mar-09 2:58

13-Mar-09 2:58

Glad to help Smile | :)

Eslam Afifi

AndyTexas22-Jun-09 6:08

AndyTexas

22-Jun-09 6:08

I see how to store the strokes DB. We've been successful at this in storing signatures from a tablet application. I now want to be able to present our signatures via a web report. I want to be able to convert my strokes directly to a png or bitmap and display using SS Reporting Services image control. So, I need to convert the strokes collection, stored in the database, to to bitmap byte[], as we're unable to use the inkcavas control in SSRS. Does anyone know how to do this?

-Andy

Eslam Afifi22-Jun-09 12:24

22-Jun-09 12:24

Adventures into Ink API using WPF[^] does that. But it outputs only the visible parts of the ink. You may want to ensure that the InkCanvas or InkPresenter is big enough to contain all the ink in it.
The StrokeCollection has a method Draw[^] that draws on a DrawingContext, maybe you want to investigate that.
By the way, you should start a new thread instead of replying to an old one to increase the probability that someone see your question and someone may have a better solution.

Eslam Afifi

WPF Tween Library

emptythetill12-Mar-09 1:56

12-Mar-09 1:56

Hello.

Has anyone come across a nice, sturdy Tweening library for WPF? Coming from Flash I have been spoiled by Tweener, TweenMax, GTween etc and am in shock that MS has not provided something similar for WPF when us designers consider it an essential.

Cheers, E.

Re: WPF Tween Library

Pete O'Hanlon12-Mar-09 2:25

Pete O'Hanlon

12-Mar-09 2:25

This Silverlight version[^] looks promising - a WPF version would be extremely simple to achieve.

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Re: WPF Tween Library

emptythetill13-Mar-09 2:50