Dropbox make it right

I was wrote about Dropbox highjacking Mac OS security. This seems finally changed. After upgrade to Mac OS Sierra I've noticed that Dropbox asking me permission to Accessibility via standard system dialog.

Next I went to Dropbox settings and changed Dropbox badge option to Never Show.

Restarted Dropbox app and voila! Dropbox have no accessibility access and not asking for this anymore!

Sadly it was not good will of Dropbox that is dictated this change. It's reported that Apple closed breach in security, so Dropbox hack is just impossible on macOS Sierra.

Dropbox highjacked your Mac security

If you're using Dropbox on Mac OS you might be surprised that Dropbox has permission to control your computer, even it's never asking permission for doing so. Even if you uncheck or remove Dropbox from Accessibility list it will reappear on next log in to computer or next start of Dropbox app. There is good articles at applehelpwritter.com on what is exact issue revealing Dropbox’s dirty little security hack and on how Dropbox do that discovering how Dropbox hacks your mac.

As for me, I'll show you how to prevent of Dropbox to highjacking Mac OS security. What we need is to remove access to execute exploit and prevent Dropbox to revert that changes.

1. Open Terminal app. Change current directory to Dropbox exploit dir. Dropbox version might be different on your computer, just choose latest if there is more than one.

cd /Library/DropboxHelperTools/Dropbox_u502

Remove executable and set-user-id bits from exploit binary. System will prompt you for admin password.

sudo chmod -sx dbaccessperm

Lock changes for exploit binary.

sudo chflags uchg dbaccessperm

2. Now uncheck permission for Dropbox in System Preferences - Security & Privacy - Privacy. You will need to Click the lock at left bottom to make changes on this page. That's it. Permissions for Dropbox will not reappear after Mac restart. Most important, there is no dialogs on every OS reboot.

You might think that more easy to just remove exploit binary but this not the case, if binary removed, Dropbox will recreate it on next start and override permissions.

If you not sure will Dropbox correctly work without controlling your computer, there is explanation why accessibility used by Dropbox app - "We use accessibility APIs for the Dropbox badge (Office integrations) and other integrations (finding windows & other UI interactions)." link. Personally I'm not using office integration and not see any problem in Dropbox functionality since I've disabled accessibility access for Dropbox.

Binding to Image Path in Isolated Storage

Bind Image Source to web address is not problem, it will works well... until You don't care about performance. Problem will appear if You want to cache images. Isolated storage is only way to store downloaded files in Silverlight not matter Browser or Windows Phone. Not so difficult to download image file from Internet and save to Isolated Storage, but how to use it in Silverlight Page?

Well, lets try to figure out. First define image converter:

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1. public class IsoImageConverter : IValueConverter    
2. {    
3.     //Convert Data to Image when Loading Data    
4.     public object Convert(object value, Type targetType, object parameter,    
5.         System.Globalization.CultureInfo culture)    
6.     {    
7.         var bitmap = new BitmapImage();    
8.         try    
9.         {    
10.             var path = (string)value;    
11.             if (!String.IsNullOrEmpty(path))  
12.             {    
13.                 using (var file = LoadFile(path))    
14.                 {    
15.                     bitmap.SetSource(file);    
16.                 }    
17.             }    
18.         }    
19.         catch    
20.         {    
21.         }    
22.         return bitmap;    
23.     }    
24.     
25.     private Stream LoadFile(string file)    
26.     {    
27.         using (var isoStore = IsolatedStorageFile.GetUserStoreForApplication())    
28.         {    
29.             return isoStore.OpenFile(file, FileMode.Open, FileAccess.Read);    
30.         }    
31.     }    
32.         
33.     public object ConvertBack(object value, Type targetType, object parameter,    
34.         System.Globalization.CultureInfo culture)    
35.     {    
36.         throw new NotImplementedException();    
37.     }    
38. }  

public class IsoImageConverter : IValueConverter { //Convert Data to Image when Loading Data public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { var bitmap = new BitmapImage(); try { var path = (string)value; if (!String.IsNullOrEmpty(path)) { using (var file = LoadFile(path)) { bitmap.SetSource(file); } } } catch { } return bitmap; } private Stream LoadFile(string file) { using (var isoStore = IsolatedStorageFile.GetUserStoreForApplication()) { return isoStore.OpenFile(file, FileMode.Open, FileAccess.Read); } } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { throw new NotImplementedException(); } }

Next define link in App.xaml for use in XAML code

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1. <local:IsoImageConverter x:Key="IsoImageCoverter"/>  

<local:IsoImageConverter x:Key="IsoImageCoverter"/>

And finally bind to string path to Isolated Storage image file

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1. <Image Source="{Binding ImagePath, Converter={StaticResource IsoImageCoverter}}"/>  

<Image Source="{Binding ImagePath, Converter={StaticResource IsoImageCoverter}}"/>

Localize ToggleSwitch in Silverlight Toolkit

Read tons of blogs and questions and answers, but cannot get Localize ToggleSwitch in SilverLight Toolkit in my Windows Phone Application. So i decided to get my own way. My proposal based on DataTemplate for ToggleSwitch and ValueConverter. So let's go.

First add Localized Resource for our new On and Off string values:

Next step create ValueConverter:

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1. public class BoolToSwitchConverter : IValueConverter  
2. {  
3.     private string FalseValue = Resources.Off;  
4.     private string TrueValue  = Resources.On;  
5.   
6.     public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)  
7.     {  
8.         if (value == null)  
9.             return FalseValue;  
10.         else  
11.             return ("On".Equals(value)) ? TrueValue : FalseValue;  
12.     }  
13.   
14.     public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)  
15.     {  
16.         return value != null ? value.Equals(TrueValue) : false;  
17.     }  
18. }  

public class BoolToSwitchConverter : IValueConverter { private string FalseValue = Resources.Off; private string TrueValue = Resources.On; public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { if (value == null) return FalseValue; else return ("On".Equals(value)) ? TrueValue : FalseValue; } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { return value != null ? value.Equals(TrueValue) : false; } }

Make our converter visible from XAML, adding glue code to Application Resources in App.xaml Add link to app namespace if you not do this before xmlns:local="clr-namespace:AppNamspace" And add resource code

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1. <Application.Resources>  
2.     <local:BoolToSwitchConverter x:Key="Switch" />  
3. </Application.Resources>  

<Application.Resources> <local:BoolToSwitchConverter x:Key="Switch" /> </Application.Resources>

And finally override DataTemplate on our ToggleSwitch:

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1. <toolkit:ToggleSwitch x:Name="MySwitch" Header="Localized Switch">  
2.     <toolkit:ToggleSwitch.ContentTemplate>  
3.         <DataTemplate>  
4.             <ContentControl HorizontalAlignment="Left"   
5.                 Content="{Binding Converter={StaticResource Switch}}"/>  
6.         </DataTemplate>  
7.     </toolkit:ToggleSwitch.ContentTemplate>  
8. </toolkit:ToggleSwitch>  

<toolkit:ToggleSwitch x:Name="MySwitch" Header="Localized Switch"> <toolkit:ToggleSwitch.ContentTemplate> <DataTemplate> <ContentControl HorizontalAlignment="Left" Content="{Binding Converter={StaticResource Switch}}"/> </DataTemplate> </toolkit:ToggleSwitch.ContentTemplate> </toolkit:ToggleSwitch>

Result:

Localize Windows Phone 7 Styles

In process of localize silverlight application, usually, localized text wider than original english. In most cases it not a problem if You use StackPanel or other wrapping conrols, but sometimes width cannot be easely changed. In silverlight application You can use satellite assembly and put localized styles, and connect to page using MergedDictionary and ResourceDictionary.

Why cannot use same approach for Windows Phone application? There is many reasons:

1. Windows Phone don't support satellite assemblies.
2. Windows Phone don't care about xml:lang
3. MergedDictionary degrade preformance

So try to use another approach. Define control, Button for example and apply default style

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1. <Button x:Name="MyStyledButton" Content="Button" Style="{StaticResource MyButton}"/>  

<Button x:Name="MyStyledButton" Content="Button" Style="{StaticResource MyButton}"/>

Then put general style in App.xaml

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1. <Style x:Key="MyButton" TargetType="Button">  
2.     <Setter Property="Background" Value="#303030"></Setter>  
3.     <Setter Property="BorderThickness" Value="0"></Setter>  
4. </Style>  

<Style x:Key="MyButton" TargetType="Button"> <Setter Property="Background" Value="#303030"></Setter> <Setter Property="BorderThickness" Value="0"></Setter> </Style>

Another bug in Windows Phone 7 that attribute BasedOn not supported, so we have to copy whole style to derived. Next step change name, adding -[lang code] to x:Key of style. So 'MyButton' will be 'MyButton-de' for example.

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1. <Style x:Key="MyButton-ru" TargetType="Button">  
2.     <Setter Property="Background" Value="#FF8080"></Setter>  
3.     <Setter Property="BorderThickness" Value="1"></Setter>  
4. </Style>  

<Style x:Key="MyButton-ru" TargetType="Button"> <Setter Property="Background" Value="#FF8080"></Setter> <Setter Property="BorderThickness" Value="1"></Setter> </Style>

Next we'll add runtime code for loading language dependent styles.

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1. string lang = CultureInfo.CurrentUICulture.TwoLetterISOLanguageName;  
2. // load localized style  
3. Style style = (Style)App.Current.Resources["MyButton-" + lang];  
4. if (style != null)  
5. {  
6.     MyButton.Style = style;  
7. }  

string lang = CultureInfo.CurrentUICulture.TwoLetterISOLanguageName; // load localized style Style style = (Style)App.Current.Resources["MyButton-" + lang]; if (style != null) { MyButton.Style = style; }

In runtime we determine current UI language and try to load altered style. If found, apply new style, if not - hardcoded style will be used.

Load Image at Background Thread in Silverlight WP7

Load image at background thread in Silverlight Windows Phone 7 application, is that possible?

Usually when you try to use BitmapImage, Image, WriteableImage in other than UI thread, you'll get exception. This is because these classes are derived from  System.Windows.Threading.DispatcherObject, which is blocked access from other than UI thread. There exists an extension to WriteableBitmap, LoadJpeg, which is works fine in thread, but you have to create WriteableBitmap object on main UI thread.

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1. using System.Windows;  
2. using System.Windows.Media.Imaging;  
3. using System.IO;  
4. using System.Threading;  
5.   
6. namespace ImageHelpers  
7. {  
8.     public delegate void ImageLoadedDelegate(WriteableBitmap wb, object argument);  
9.   
10.     public class ImageThread  
11.     {  
12.         public event ImageLoadedDelegate ImageLoaded;  
13.   
14.         public ImageThread()  
15.         {  
16.         }  
17.   
18.         public void LoadThumbAsync(Stream src, WriteableBitmap bmp, object argument)  
19.         {  
20.             ThreadPool.QueueUserWorkItem(callback =>  
21.             {  
22.                 bmp.LoadJpeg(src);  
23.                 src.Dispose();  
24.                 if (ImageLoaded != null)  
25.                 {  
26.                     Deployment.Current.Dispatcher.BeginInvoke(() =>  
27.                     {  
28.                         ImageLoaded(bmp, argument);  
29.                     });  
30.                 }  
31.             });  
32.         }  
33.     }  
34. }  

using System.Windows;<br /> using System.Windows.Media.Imaging;<br /> using System.IO;<br /> using System.Threading;<br /> <br /> namespace ImageHelpers<br /> {<br /> public delegate void ImageLoadedDelegate(WriteableBitmap wb, object argument);<br /> <br /> public class ImageThread<br /> {<br /> public event ImageLoadedDelegate ImageLoaded;<br /> <br /> public ImageThread()<br /> {<br /> }<br /> <br /> public void LoadThumbAsync(Stream src, WriteableBitmap bmp, object argument)<br /> {<br /> ThreadPool.QueueUserWorkItem(callback =><br /> {<br /> bmp.LoadJpeg(src);<br /> src.Dispose();<br /> if (ImageLoaded != null)<br /> {<br /> Deployment.Current.Dispatcher.BeginInvoke(() =><br /> {<br /> ImageLoaded(bmp, argument);<br /> });<br /> }<br /> });<br /> }<br /> }<br /> }<br />

Using scenario:

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1. ImageThread imageThread = new ImageThread();  
2.   
3. private void Init()  
4. {  
5.     imageThread.ImageLoaded += LoadFinished;  
6. }  
7.   
8. void LoadFinished(WriteableBitmap bmp, object arg)  
9. {  
10.     Imgage1.Source = bmp;  
11. }  
12.   
13. void DeferImageLoading( Stream imgStream )  
14. {  
15.     // we have to give size  
16.     var bmp = new WriteableBitmap(80, 80);  
17.     imageThread.LoadThumbAsync(imgStream, bmp, this);  
18. }  

ImageThread imageThread = new ImageThread();<br /> <br /> private void Init()<br /> {<br /> imageThread.ImageLoaded += LoadFinished;<br /> }<br /> <br /> void LoadFinished(WriteableBitmap bmp, object arg)<br /> {<br /> Imgage1.Source = bmp;<br /> }<br /> <br /> void DeferImageLoading( Stream imgStream )<br /> {<br /> // we have to give size<br /> var bmp = new WriteableBitmap(80, 80);<br /> imageThread.LoadThumbAsync(imgStream, bmp, this);<br /> }<br />

Using WP7 Profiler

Windows Phone 7 SDK RC add exciting new feature to developers. After installed new developer tools I noticed Microsoft Windows Phone 7.1 Profiler in About menu of Visual studio 2010 for Windows Phone. Quick Googling give no results, but everything more easy than can looks.

Open Your WP7 project and look into Debug menu. You will see disabled (probably not) menu item Start Windows Phone Performance Analysis

To enable this item You have to switch Your project target from Windows Phone 7.0 to 7.1 in Project -> Properties menu. So if Your application targeted current market, you have to make project clone prior profiling, cause You cannot switch back to 7.0.

When application targeted Mango You can open profiler. Choose options and click hyperlink Launch Application.

After working with application click Stop Profiling. After analysis You will see profiling results. Select timeline and it shows details.

Update: Finally found MSDN Page, describing WP7 Profiler