Updating sql database from a listbox

08-May-2019 21:44 by 5 Comments

Updating sql database from a listbox

In the case of the Minimum and Maximum example, if the “base” value of the Maximum property is less than the Minimum value, then the “effective” value of the Maximum property becomes equal to the Minimum value.

The Affects Parent Measure and Affects Parent Arrange flags will cause Invalidate Measure() and Invalidate Arrange() to be called, respectively, on the target element’s parent.The Silverlight Slider control attempts to do this.Unfortunately, this can lead to code that is cumbersome to maintain, especially if you need to use the same mechanism in several different classes.The quintessential example can be found within the Slider control. Clearly, it would be a problem if the Maximum value were allowed to fall below the Minimum value.Value coercion is used to prevent this invalid state from occuring.Furthermore, achieving parity between frameworks can prove to be very difficult.

As evidence of this, note that the pseudo-coercion within Silverlight’s native Slider control is just wrong.Effective Value It is important to recognize that with value coercion, a dependency property has both a “base” (or “desired”) value and an “effective” (or “coerced”) value.The “base” value is always passed into the Coerce Value Callback and the value returned from that method becomes the new “effective” value.That means if either the Minimum or Maximum values change, the Value property must explicitly be coerced.As such, the property changed callback for the Maximum property also coerces the Value property, something like this: Base Value vs.If the Maximum value happens to be less than the Minimum value, the function will coerce it to be equal to the Minimum value so that it is valid.