adornerlayer | 易学教程

In WPF, how to display AdornerLayer on top of DataGrid

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问题 I am using WPF datagrid from codeplex. I am using DatagridTemplateColumn and I have written datatemplates to display contents in each column. Now I have to display some help message to a user when the any control in datagrid is focussed. For this I thought of using adorner layer. I used ComboBox loaded event and accessed the adrorner layer of it. I then added my own adorner layer with some thing to be displayed there similar to tooltip. Below is the code. TextBox txtBox = (TextBox)comboBox

GetAdornerLayer mysteriously returning null

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问题 I've been using the same bit of code for several versions of my app with no problems, but I'm now mysteriously receiving NullRerefenceException s with the following: this.Loaded += delegate { deleteBrush = new DeleteBrushAdorner( background ); AdornerLayer al = AdornerLayer.GetAdornerLayer( background ); al.Add( deleteBrush ); // null ref here?? }; background is just a Border element. My two thoughts on what could be causing it are a) switching to .NET 4.0, and b) placing instances of the

GetAdornerLayer mysteriously returning null

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Initial validation on dynamically added control

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问题 WPF validation system performs intial validatation of an object (I mean - all fields are validated when a databound item is changed, and results are displayed on the ui). But it doesn't work like this, when I add a control dynamically. In such case inital validation happens, but results aren't shown on the ui. Only after some properties on a databound object change, everything starts working correctly. Here's a crude sample. Suppose we have MyObject class public class MyObject :

What's the point to WPF adorners?

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问题 I've recently developed a drawing component for my company, featuring a Canvas on which you can draw certain shapes using click-and-drag. For each shape, I placed two adorners on its AdornerLayer: One for increased hit detection (basically a transparent rectangle that would exceed the shape's boundaries by a few pixels), and another for resizing (four Thumb controls on the corners). But, I ran into many problems when implementing some of the features of the component, all adorner related.

Validation ErrorTemplate not showing on data errors

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问题 This is a bit of a WPF whodunnit! My validation temples it not appearing when expected The Problem Basically, I am using IDataErrorInfo on my view model to provide feedback on data entry errors. I can see this being called and working as expected, but the validation error template for the bound control is never displayed by WPF! I have tried both using the built-in default textbox red border error template, a style error template, and a hard coded template. None of these are displayed in a

AdornerLayer.GetAdornerLayer() return NULL for all controls in a Panel

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问题 I'm facing the fact that i cannot understand Well how AdornerLayer is added for UIElements. I have such a situation: I have a WPF Form which is built with 3 controls: A Grid on which are 1 Button and 1 TextBox . In my System, when I click to open this Form, all 3 elements have AdornerLayer not null . var controls = _frameworkElementProvider.GetUIElements(Content); var controlsWithAddorner = new List<FrameworkElement>(); foreach (var control in controls) { var adornerLayer = AdornerLayer

Why AdornerLayers are always the top most layers? Is there a way to change it?

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问题 Why is that the adorner layer is always rendered as the top most layer in an application (under AdornerDecorator - refer screenshot)? Is there a way to change the layer/level on to which the adorners can be drawn? In the following screenshot, AdornerLayer is added to AdornerDecorator and the Adorners (MyAdorners) are added to this AdornerLayer. But the AdornerLayer is retrieved like this, AdornerLayer layer1 = AdornerLayer.GetAdornerLayer(button1); layer1.Add(new MyAdorner(button1)); 回答1: To

What's the point to WPF adorners?

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I've recently developed a drawing component for my company, featuring a Canvas on which you can draw certain shapes using click-and-drag. For each shape, I placed two adorners on its AdornerLayer: One for increased hit detection (basically a transparent rectangle that would exceed the shape's boundaries by a few pixels), and another for resizing (four Thumb controls on the corners). But, I ran into many problems when implementing some of the features of the component, all adorner related. They captured all preview events, since they were in another visual tree than the Canvas itself, that was

Why AdornerLayers are always the top most layers? Is there a way to change it?

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Why is that the adorner layer is always rendered as the top most layer in an application (under AdornerDecorator - refer screenshot)? Is there a way to change the layer/level on to which the adorners can be drawn? In the following screenshot, AdornerLayer is added to AdornerDecorator and the Adorners (MyAdorners) are added to this AdornerLayer. But the AdornerLayer is retrieved like this, AdornerLayer layer1 = AdornerLayer.GetAdornerLayer(button1); layer1.Add(new MyAdorner(button1)); To answer my second question, Is there a way to change the layer/level on to which the adorners can be drawn? I