控制器数据绑定 vs 事件处理程序
即使早期的XBAP项目几乎要完全依赖数据绑定，但在学习完这个领域的知识后，我们发现在Silverlight 2中的数据绑定仍然不够实用，既没有ElementName属性也没有Path属性，相反，我们使用了一系列的事件处理程序来设置TextBlock的文本属性，它与TextBox的为文本属性相当。
作者注记：要查看数据绑定在Silverlight中的地位，请参考silverlight.net上的这篇文章http://www.devx.com/RIA/link/38130）。
设置TextBlock的文本属性
private void txtFirstName_TextChanged
(object sender, TextChangedEventArgs e)
{//When the user types into the First Name textbox,
add the same text in the First Name textblock
txbFirstName.Text = txtFirstName.Text;
PositionTextBlockInCanvas(txbFirstName);
//Adjust the location if it would fall
//outside the Imprint Area
If (txbFirstName.Text.Length == 0)
{//Also, unhide the And Character whenever the
//First Name textblock contains one or more letters
txbAndCharacter.Visibility = Visibility.Collapsed;
}
else
{
txbAndCharacter.Visibility = Visibility.Visible;
}
}
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在这个示例代码中，AndCharacter TextBlock 的Visibility属性连接到FirstName TextBlock的文本属性Length了。当FirstName TextBlock中没有内容时，AndCharacter TextBlock就不可见，但当用户在FirstName TextBlock中输入字符时，AndCharacter TextBlock就自动被设为可见了。
改变水印颜色浮动TextBlock的Foreground属性）是通过事件处理程序完成的，MouseEnter事件程序创建一个SolidColorBrush，它匹配当前鼠标下方框内的颜色然后调用哪个ApplyNewImprintColor方法。
Silverlight 2改变浮动TextBlock的Foreground属性
＜!-- Colored rectangles representing Drink Mate standard imprint colors --＞
＜Rectangle x:Name="ImprintColorRectangle1"
Height="30" Width="30" Fill="#000000" Stroke="#FFFFFF" StrokeThickness="0"
MouseEnter="handleMouseEnterImprintColors"
MouseLeftButtonDown="handleImprintColorClick"
MouseLeave="handleMouseLeaveImprintColors" /＞＜! --Black --＞
＜Rectanglex:Name="ImprintColorRectangle2"
Height="30"
Width="30" Fill="#000099"
Stroke="#FFFFFF"
StrokeThickness="0"
MouseEnter="handleMouseEnterImprintColors"
MouseLeave
="handleMouseLeaveImprintColors"
MouseLeftButtonDown
="handleImprintColorClick" /＞＜! --Reflex Blue --＞
＜Rectangle x:Name="ImprintColorRectangle3"
Height="30" Width="30"
Fill="#0000CC"
Stroke="#FFFFFF"
StrokeThickness="0"
MouseEnter="handleMouseEnterImprintColors"
MouseLeave="handleMouseLeaveImprintColors"
MouseLeftButtonDown="handleImprintColorClick" /＞＜! -- Medium Blue --＞
＜Rectangle x:Name="ImprintColorRectangle4"
Height="30" Width="30"
Fill="#3232FF" Stroke="#FFFFFF" StrokeThickness="0"
MouseEnter="handleMouseEnterImprintColors"
MouseLeave="handleMouseLeaveImprintColors"
MouseLeftButtonDown="handleImprintColorClick" /＞＜! -- Process Blue --＞
private void handleMouseEnterImprintColors(object
sender, MouseEventArgs e)
{
Rectangle rect = (Rectangle)sender;
SolidColorBrush newImprintColor = (SolidColorBrush)rect.Fill;
ApplyNewImprintColor(newImprintColor);
bdrTooltips.Visibility = Visibility.Visible;
txbTooltips.Text = "Click to change the imprint color.";
}
private void ApplyNewImprintColor(SolidColorBrush newImprintColor)
{
try
{
txbFirstName.Foreground = newImprintColor;
txbAndCharacter.Foreground = newImprintColor;
txbSecondName.Foreground = newImprintColor;
txbEventDate.Foreground = newImprintColor;
}
catch (System.Exception ex)
{
Console.WriteLine(ex.Message);
}
}
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