Resources, styles, control templates, and themes in Visual C#

Making PDF417 in Visual C# Resources, styles, control templates, and themes

Resources, styles, control templates, and themes
PDF 417 Encoder In Visual C#.NET
Using Barcode maker for Visual Studio .NET Control to generate, create PDF 417 image in Visual Studio .NET applications.
www.OnBarcode.com
PDF417 Recognizer In C#.NET
Using Barcode decoder for Visual Studio .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Now that WPF is here, you don t have to mess around with any of that. You can still set properties to specific values, but you can also set a property s value to depend on the value of something that might change. If your background points at a particular resource dictionary, by changing the value in that dictionary, anything that references that value can be set to automatically change.
Draw DataMatrix In Visual C#
Using Barcode creation for Visual Studio .NET Control to generate, create Data Matrix 2d barcode image in VS .NET applications.
www.OnBarcode.com
PDF417 Encoder In Visual C#
Using Barcode maker for Visual Studio .NET Control to generate, create PDF 417 image in .NET applications.
www.OnBarcode.com
The Property System
Generate Code 128B In Visual C#.NET
Using Barcode creator for VS .NET Control to generate, create Code 128A image in VS .NET applications.
www.OnBarcode.com
Barcode Generator In C#
Using Barcode generation for Visual Studio .NET Control to generate, create Barcode image in .NET applications.
www.OnBarcode.com
You might think that there is a member variable behind each property you set on a control or other WPF object. Given the number of properties available, though, even if each variable only took up 4 bytes, each control would end up eating a fair amount of memory, and that memory would be used even if you never set the value away from the default. Instead, each WPF object has its own dictionary of property values. This way, objects only use memory when the property has been set, a much more efficient approach. The Property System also provides a whole bunch of other capabilities, including the automatic retrieval of parent values and the ability to handle dynamic properties that change automatically when their dependency changes. Attached properties also depend on the use of this dictionary. The property dictionary can hold property values even if the particular control doesn t understand what they re for (like Dock.Left).
Draw QR Code In Visual C#.NET
Using Barcode encoder for VS .NET Control to generate, create QR Code JIS X 0510 image in Visual Studio .NET applications.
www.OnBarcode.com
Code-27 Generation In Visual C#
Using Barcode generation for .NET framework Control to generate, create Code-27 image in VS .NET applications.
www.OnBarcode.com
Because WPF handles properties in a consistent way, it s easy to set up this dynamic behavior. Let s take the border example from before, where we referenced a brush from a resource:
Generating PDF-417 2d Barcode In None
Using Barcode creator for Software Control to generate, create PDF417 image in Software applications.
www.OnBarcode.com
Create PDF 417 In None
Using Barcode drawer for Online Control to generate, create PDF417 image in Online applications.
www.OnBarcode.com
<Button BorderBrush="{StaticResource myBrush}" ...>7</Button>
Reading Barcode In Visual Studio .NET
Using Barcode reader for .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
Code 39 Decoder In .NET Framework
Using Barcode decoder for VS .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
The use of StaticResource means that the value for the brush will be retrieved once and then used from that point forward. When the XAML is read, the system immediately retrieves the value for myBrush, sets the border appropriately, and then forgets about it. If we change static to dynamic, we get different behavior:
Painting EAN / UCC - 14 In Visual Studio .NET
Using Barcode maker for ASP.NET Control to generate, create USS-128 image in ASP.NET applications.
www.OnBarcode.com
Draw QR Code In Objective-C
Using Barcode encoder for iPhone Control to generate, create QR Code ISO/IEC18004 image in iPhone applications.
www.OnBarcode.com
<Button BorderBrush="{DynamicResource myBrush}" ...>7</Button>
Code 128 Code Set C Creator In VS .NET
Using Barcode creation for Reporting Service Control to generate, create Code 128A image in Reporting Service applications.
www.OnBarcode.com
USS-128 Generation In None
Using Barcode generator for Excel Control to generate, create EAN / UCC - 14 image in Excel applications.
www.OnBarcode.com
DynamicResource is fancier. When the system goes to handle this XAML, it doesn t
Recognizing Barcode In Visual Basic .NET
Using Barcode reader for .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
ANSI/AIM Code 128 Creation In VS .NET
Using Barcode maker for ASP.NET Control to generate, create ANSI/AIM Code 128 image in ASP.NET applications.
www.OnBarcode.com
assign a value immediately; instead, it puts in an expression. That expression isn t evaluated until the value is needed. This is an important distinction: The DynamicResource is lazy-loaded, so the item referenced doesn t have to exist at the point when the XAML is read. With a StaticResource, if the item referenced doesn t exist when the XAML is read, an exception is thrown. In the case of the example, that s not a problem, but the resource could be something you create at runtime (maybe it s a user preference). The same approach is used for data binding, where it s less likely that the data is available before the XAML is read. The behavior of a DynamicResource goes further than lazy loading. Instead of having a value assigned to the property, a connection is made such that, if the referenced
EAN13 Printer In Visual Studio .NET
Using Barcode encoder for Reporting Service Control to generate, create UPC - 13 image in Reporting Service applications.
www.OnBarcode.com
European Article Number 13 Maker In VB.NET
Using Barcode creation for .NET framework Control to generate, create EAN-13 Supplement 5 image in Visual Studio .NET applications.
www.OnBarcode.com
Resources
value changes, the property also changes with it. Let s modify the calculator so that one button uses a static resource and one a dynamic:
<Button BorderBrush="{DynamicResource myBrush}" ...>7</Button> <Button BorderBrush="{StaticResource myBrush}" ...>8</Button>
Now, we can add some code to the OnClickOperator (from the last chapter) method to change the brush when the user hits any operator button (listing 6.6). This might seem like a silly example. Okay, this is a silly example. But, if we took it a little further, it could be made into a nice little UI hint it isn t always obvious that the user has hit the button and the color change could be used to indicate the last button pressed.
Listing 6.6 Changing Brush when user hits an operator
private void OnClickOperator(object sender, RoutedEventArgs e) { Button btn = sender as Button; OperatorHolder holder = btn.Content as OperatorHolder; ExecuteLastOperator(holder.Operator); this.Resources["myBrush"] = new SolidColorBrush(Colors.Gray); }
All we re doing here is updating the Window s myBrush resource to be a gray brush instead of the red brush we already had. Note that we aren t doing anything to tell the system to redraw the buttons or update their values, yet the dynamically set button gets updated anyway (figure 6.4). Notice also that the static button s color doesn t change. If you want to set up a dynamic property value via code, it s fairly straightforward. Instead of setting the property value directly, you have to use a special method on the control, called SetResourceReference. For example, if we want the 9 button to use the brush dynamically, we d do the following:
button9.SetResourceReference(Button. BorderBrushProperty,"myBrush");
Figure 6.4 The border around the 7 button changes automatically when we update the resource. The color around the 8 button doesn t because it uses a static resource reference.
This sets the button s border color to the value in myBrush, and that value is updated whenever the myBrush resource changes. Notice that we re passing Button.BorderBrushProperty as the property to set. This is a dependency property, and we ll explain what that means in the next section.
Copyright © OnBarcode.com . All rights reserved.