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Posts tagged with 'winforms'

Setting tab stops in a Windows Forms TextBox control

c# winforms SendMessage pinvoke textbox EM_SETTABSTOPS 2 Comments Downloads

I was adding a Wizard to one of my applications, and the final screen of this Wizard was a summary of the user's choices. I wanted the user to be able to copy this to the Clipboard if required, and so I'd used a TextBox rather than the ListView I might have otherwise used. However, this presented a minor issue as I'd chosen to use tabs to delimit the information, and the varying length of text meant that this wasn't aligned as expected.

Previously I have "dealt" with this issue by cheating - I'd just add extra tabs to force everything to line up. However, I do plan on fully localising this application at some point, not to mention that even using a different font could potentially trigger the text to misalign once more. And so I decided to do it properly this time.

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Using message filters in Windows Forms applications

c# winforms pinvoke IMessageFilter 0 Comments Downloads

For a utility application, I wanted to add an item in the system menu. It's been quite a long time since I last did this (and was in VB6), so I decided to find some ready made source code. This class provides a nice little helper for wrapping the system menu to add new commands to it, but it requires the owner form to hook into its window procedure and forward messages on which I felt was an awkward design.

The code snippets below should illustrate my point - first we initialise the instance of the SystemMenu class, but in order for custom commands to be processed we have to override to override the form's WndProc and pass any messages received into the SystemMenu class.

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Displaying text in an empty ListBox

c# winforms WM_PAINT listbox wm_erasebkgnd 3 Comments Downloads

While looking at ways of improving the UI of a dialog in an application, I wanted to display some status text in a ListBox control that was empty. The default Windows Forms ListBox (which uses the underlying native Win32 control) doesn't support this, but with a little effort we can extend the control.

When a Control receives either the WM_PAINT or WM_ERASEBKGND messages, it will check to see if the ControlStyles.UserPaint style is set. If set then the WM_PAINT message will cause the Paint event to be raised, and for WM_ERASEBKGND the PaintBackground event - but only if the the AllPaintingInWmPaint style is not set.

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Displaying multi-page tiff files using the ImageBox control and C#

c# winforms imagebox tiff sample 1 Comments Downloads

Earlier this week I received a support request from a user wanting to know if it was possible to display multi-page tiff files using the ImageBox control. As I haven't wrote anything about this control for a while, it seemed a good opportunity for a short blog post.

One you have obtained an Image instance containing your tiff graphic, you can use the GetFrameCount method in conjunction with a predefined FrameDimension object in order to determine how many pages there are in the image.

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Aligning Windows Forms custom controls to text baselines using C#

c# winforms designer 1 Comments Downloads

One of the nice things about the Visual Studio WinForms designers are the guidelines it draws onto design surfaces, aiding you in perfectly positioning your controls. These guidelines are known internally as snap lines, and by default each visual component inheriting from Control gets four of these, representing the values of the control's Margin property.

A problem arises when you have multiple controls that have different heights, and contain a display string - in this case aligning along one edge isn't going to work and will probably look pretty ugly. Instead, you more than likely want to align the different controls so that the text appears on the same line.

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Adding keyboard accelerators and visual cues to a WinForms control

c# winforms keyboard mnemonic 0 Comments Downloads

Some weeks ago I was trying to make parts of WebCopy's UI a little bit simpler via the expedient of hiding some of the more advanced (and consequently less used) options. And to do this, I created a basic toggle panel control. This worked rather nicely, and while I was writing it I also thought I'd write a short article on adding keyboard support to WinForm controls - controls that are mouse only are a particular annoyance of mine.

Below is an fairly simple (but functional) button control that works - as long as you're a mouse user. The rest of the article will discuss how to extend the control to more thoroughly support keyboard users, and you what I describe below in your own controls.

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Hosting a ColorGrid control in a ToolStrip

c# winforms colorpicker toolstrip 2 Comments

The ColorGrid control is a fairly useful control for selecting from a predefined list of colours. However, it can take up quite a bit of screen real estate depending on how many colours it contains. This article describes how you can host a ColorGrid in a standard ToolStrip control, providing access to both the ColorGrid and the ColorPickerDialog.

The ToolStrip control makes this surprisingly easy to accomplish. First, we're going to need a component to host the ColorGrid which we can ably achieve by inheriting from ToolStripDropDown. So lets get started!

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Adding Double Click support to the ComboBox control

c# winforms interop combobox GetComboBoxInfo COMBOBOXINFO NativeWindow WM_LBUTTONUP WM_LBUTTONDBLCLK 1 Comments Downloads

I was recently using a ComboBox control with the DropDownStyle set to Simple, effectively turning into a combined text box and list box.

However, when I wanted an action to occur on double clicking an item in the list I found that the control doesn't actually offer double click support. I suppose I should have just ripped out the combo box at that point and went with dedicated controls but instead I decided to extend ComboBox to support double clicks.

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Dragging items in a ListBox control with visual insertion guides

c# winforms drag and drop insertion WM_PAINT listbox 2 Comments Downloads

In my last post, I described how to drag and drop items to reorder a ListView control. This time I'm going to describe the exact same technique, but this time for the more humble ListBox.

The code below assumes you are working in a new class named ListBox that inherits from System.Windows.Forms.ListBox.

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Dragging items in a ListView control with visual insertion guides

c# winforms listview drag and drop insertion WM_PAINT 7 Comments Downloads

I can't remember when it was I first saw something being dragged with an insertion mark for guidance. Whenever it was, it was a long long time ago and I'm just catching up now.

This article describes how to extend a ListView control to allow the items within it to be reordered, using insertion guides.

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