Develop Reference

How to create an 1 pixel wide window using C# and WinForm

I would like to create an application that have a small window displayed at the bottom corner of desktop. On startup, the window shall be very small and ideally, just a couple of pixels in width.
Here is the code I used to do it:
public partial class DurationT64 : Form
{
private Size fullSize;
private Point fullPos;
private Point compactPos;
public DurationT64()
{
InitializeComponent();
var workingArea = Screen.PrimaryScreen.WorkingArea;
this.MinimumSize = new Size(0, this.Height);
this.MaximumSize = new Size(this.Width, this.Height);
// fullPos: the window location when it is in full size form.
fullPos = new Point(workingArea.Right - this.Width, workingArea.Bottom - this.Height);
this.Location = fullPos;
// fullSize: the size of the windown when it is in full size form.
fullSize = new Size(this.Width, this.Height);
this.Size = fullSize;
// compactPos: the window location when it is in compact size form.
compactPos = new Point(workingArea.Right - 30, fullPos.Y);
this.Width = 1;
this.Location = compactPos;
}
}
As you can see that in this example, I intended to create a window of just 1 pixel in width, placed closed to the right edge of the primary monitor.
However, I realized that the window doesn't go as small as I was expected. It goes down to 20 pixels wide but no less than that. Please refer to this screen capture image below for example:
an image shows that the window is wider than it suppose to be
I did some research regards to this problem and noticed that there was a solution proposed by Zach Johnson (#zach-johnson) back in 2009. Here is the link to it Overcome OS Imposed Windows Form Minimum Size Limit.
However, nether methods proposed in that link (the intercepting WM_ message one proposed by Zach and the SetBoundsCore one proposed by #Ace) works for me.
Can anyone please give me some solution to this question? Preferably, a solution purely based on C#/Winform and does not rely on native Win32 window message loop, if possible.
Many thanks!

It is rather straight-forward, Winforms ensures that the window cannot be made smaller than the system-imposed minimum size of a window, exposed as the SystemInformation.MinWindowTrackSize property in .NET. This is a "safety" setting, it ensures that the user cannot make the window too small when he resizes it, thus losing control over it. Same consideration applies to code.
Bypassing this limit requires no magic, you need to do two things:
Set the FormBorderStyle property to None so the user cannot resize the window.
Set the size after the window is created. The Load event is best.
Some comments about your existing code: be careful about tinkering with the Width/Height/Size properties, you are doing too much of it in your constructor and it cannot work correctly. In the constructor they don't yet match the actual size of the window. And will not be close at all on modern machines with high-resolution monitors, auto-scaling to match the DPI of the video adapter is important today. You have to postpone until the window is created and scaling is complete, the Load event is the proper place for code like this. One of the few reasons to actually use Load.
And note that your Location property calculation is inadequate, it does not consider the location of the taskbar. It doesn't work on my machine, I like the taskbar on the right.
Minimum repro:
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
this.FormBorderStyle = FormBorderStyle.None;
}
protected override void OnLoad(EventArgs e) {
this.Width = 1;
base.OnLoad(e);
}
}
Do keep in mind that you'll need hawk-eyes to find it back on the screen :)

XNA How to display what is underneath the game window?

What I would like to do is to simply display a Texture2D on the screen, the screen needs to be transparent as well. I already have a section of code I found which can make the window borderless.
IntPtr hWnd = this.Window.Handle;
var control = System.Windows.Forms.Control.FromHandle(hWnd);
var form = control.FindForm();
form.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
When put into the Initialize() method, this successfully makes the window borderless.
however, when I use a GraphicsDevice.Clear(Color.Transparent); in my Draw all it results in is a black square in the middle of my screen.
Is there a way to change the opacity of the background at all? Is there anything else I can try to fix this?
Some things I heard of were to take a screenshot of the background and display it on the screen via backbuffer, however I can't find any solutions that successfully implement that.
EDIT: Here is the draw method, while rather simple
protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(Color.Transparent);
spriteBatch.Begin();
{
spriteBatch.Draw(tex, parameters, Color.White );
}
spriteBatch.End();
base.Draw(gameTime);
}
I also found I can change the forms opacity via form.opacity = 0; but that makes the texture transparent as well.

Prevent Window Centering in XNA

When I set the position of my game window using form.DesktopLocation(new Point(X, Y);, it works, but then XNA automatically resets it to the center of the screen. I tried googling and looking on stack overflow, but I can't seem to figure out how to prevent it centering. Any ideas?
Here's my code manipulating the GraphicsDevice, GraphicsDeviceManager, and the Form controlling the game:
// in the initialiser
window = (Form)Form.FromHandle(Window.Handle);
GraphicsDeviceManager = new GraphicsDeviceManager(this);
// in the draw method
g.PreferredBackBufferWidth = Width;
g.PreferredBackBufferHeight = Height;
g.ApplyChanges();
f.DesktopLocation = new System.Drawing.Point(X, Y);
And that's literally everything. I tried setting the desktop location more than once each frame, before and after the g.ApplyChanges(), and that doesn't change anything.
However, just now, I tried removing the g.ApplyChanges() and it doesn't do it anymore. Odd. Why would running a g.ApplyChanges() before changing the form only sometimes recenter the form AFTER I positioned the form?

There is no solution to this question.
XNA automatically resets the position of the window to the center of the screen on g.ApplyChanges, and whenever it hits another window-related operation, such as resizing, or moving the window from one monitor to another.
This is a problem in XNA, not with XNA code. XNA was written with no way to prevent this because their focus is on content, not windows. Therefore, if you want greater control over your forms, it's a better idea to not use XNA at all, or use XNA's output in a form you set up.

Keep my form above the taskbar?

My overall goal is to render a second (or third, fourth...) mouse cursor. To this end, I have created a frameless, topmost, transparent window. I can draw on this window (I have 4 buttons on it to show that it's properly covering the whole desktop) - but when I click on the taskbar, it is brought to the top and overlays my buttons and drawn line.
How can I keep my window above the taskbar?
Alternatively, is there a way that I can draw on the "final" version of the screen?
Here's the code from my .Designer.cs file:
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.None;
this.BackColor = System.Drawing.Color.White;
this.CausesValidation = false;
this.ClientSize = new System.Drawing.Size(332, 332);
this.ControlBox = false;
this.Controls.Add(this.button4);
this.Controls.Add(this.button3);
this.Controls.Add(this.button2);
this.Controls.Add(this.button1);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
this.MaximizeBox = false;
this.MinimizeBox = false;
this.Name = "Screen";
this.ShowIcon = false;
this.SizeGripStyle = System.Windows.Forms.SizeGripStyle.Hide;
this.StartPosition = System.Windows.Forms.FormStartPosition.WindowsDefaultBounds;
this.TopMost = true;
this.TransparencyKey = System.Drawing.Color.White;

Without analysing the exact motivation of doing this and whether this approach is the best way through, you should note that the taskbar's behaviour is equivalent to the one of any other window: TopMost can be used without any restriction. On the other hand, it is considered outside the "WorkingArea" and thus, depending upon the properties you are using, it might be ignored. Take a look at the sample codes below to understand this better.
Main Form covering all the available space above the taskbar:
this.ClientSize = new System.Drawing.Size(Screen.PrimaryScreen.WorkingArea.Width, Screen.PrimaryScreen.WorkingArea.Height);
this.Location = new Point(Screen.PrimaryScreen.WorkingArea.Left, Screen.PrimaryScreen.WorkingArea.Top);
Main Form covering the whole available space of the screen:
this.ClientSize = new System.Drawing.Size(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height);
this.Location = new Point(Screen.PrimaryScreen.WorkingArea.Left, Screen.PrimaryScreen.WorkingArea.Top);
Thus, you can locate your form on top of the taskbar without any problem by bearing the mind that it represents the difference between WorkingArea and Bounds of the screen.
CLARIFICATION: this answer highlights what might be the reason for the taskbar to be treated differently than any other part of the screen. It does not imply that you have to make your form as big as the whole screen to put it over the taskbar; you can put it over the taskbar whenever you want with an as small size as you wish. What you have to bear in mind is that WorkingArea does not provide the whole dimensions of the screen, but just the area ABOVE the taskbar; if you want to bring the taskbar into consideration, consider Bounds.

I'll go with varocarbas answer,but there is something that i want to add which i think might be useful.
A few things are there that i guess may be helpful,when i read your question the first idea that struck my mind was to create a GlobalHook to monitor message WM_CBT,this message is send to GlobalHook procedure when the system is about to Maximize,Minimize,Restore or Focus a Window.When any hook is trapped you can override any required events to block that window from becoming the topmost window,thus giving your Form a chance to remain the topmost Window.This method will be highly helpful if it worked as i am expecting.
If you are interested in this, here are the methods that are required to make a GlobalHook work.
SetWindowsHookEx(),used to tell the system to create a GlobalHook.
HookProc,Represents the method called when a hook catches a monitored event.
HookType,Enumerates the valid hook types passed into a call to SetWindowsHookEx.
CallNextHook.If using interoperability is messy,try this open source library that contains WindowsAPI functions in a managed wrapper.Hope this helps you,meanwhile i'm also trying to get the stuff working for you.

I've been struggling for a few hours with this same problem. I thought of a nice solution: just change the bottom padding of the form dynamically whenever the form is maximized.
If Me.WindowState = FormWindowState.Maximized then
Dim pd As New Padding
pd.Left = Me.Padding.Left
pd.Right = Me.Padding.Right
pd.Top = Me.Padding.Top
pd.Bottom = Me.Height - Screen.PrimaryScreen.WorkingArea.Height
Me.Padding = pd
end if
This way the form is not above the taskbar, but at least your controls are!
Note: in designing your forms you can leave the bottom-padding 0.
If you want your form to be able to minimize/normal resize, then you may want to reset the bottom padding to 0 in another form event.

I actually found the solution about 15 minutes after I posted. (Isn't that always the way? Research for hours, but as soon as you ask for help, you figure it out on your own. :)
I have an event that is calling my code with position updates. If I simply call "BringToFront" in this event, it works just fine. The event is called many times per second, but if I throttle my behavior back to 1/4 second, it still works great.

How can I make a background panel from a form transpart/invisible in an XNA window?

I have an XNA project that utilizes the Windows.Forms to create the GUI. Our GUI consists of a left panel and right panel. They both have a image laid over them(let's call them the panel images). Those images have buttons with images over them. Now the panel images don't completely cover the panel. Now what we want to do is make the panel invisible or transparent so you only see the panel images. In the picture below I circled what I want to be transparent/invisible. As you can see on the upper part of the project it already looks transparent but that is only because it blends in with the background on the XNA scene. On the bottom where the panel is over the ground you can see how the panel extends further than the panel images. So, does anyone know how I can make those parts invisible/transparent.
Alright, we've messed around with making the panel color Color.Transparent, magenta(XNA transparent color) and those attempts haven't worked. Any input/advice is welcome and much appreciated.
Here is the code that sets up the panel:
this.pnlLeftSide.BackgroundImage = global::Referenceator_UI.Resources.LeftBar;
this.pnlLeftSide.BackgroundImageLayout = System.Windows.Forms.ImageLayout.None;
this.pnlLeftSide.Controls.Add(this.btnScreenShot);
this.pnlLeftSide.Controls.Add(this.btnScale);
this.pnlLeftSide.Controls.Add(this.btnMove);
this.pnlLeftSide.Controls.Add(this.btnRotate);
this.pnlLeftSide.Controls.Add(this.btnSelect);
this.pnlLeftSide.Location = new System.Drawing.Point(0, 0);
this.pnlLeftSide.Name = "pnlLeftSide";
this.pnlLeftSide.Size = new System.Drawing.Size(197, Screen.PrimaryScreen.WorkingArea.Height);
this.pnlLeftSide.Dock = DockStyle.Left;
this.pnlLeftSide.BackColor = controlColor; //this what we want invisible/transparent
-Thank you stackoverflow community

Try setting Region property of your panels. You can create necessary Region objects manually (by enumerating lines describing visible polygon) or use some method which converts image with transparency color key to Region (easily googled - https://stackoverflow.com/questions/886968/how-do-i-convert-an-images-transparency-into-a-region for example).
Since geometry of your panels does not seem to be too complex, you can create Region manually following way:
using(var gp = new System.Drawing.Drawing2D.GraphicsPath())
{
// Here goes series of AddLine() calls.
// You must
// gp.AddLine(0, 0, leftPanel.Width, 0);
// ...
gp.CloseFigure();
return new Region(gp);
}
Note that you'll get sharp edges with this method (even if it works). Consider rendering all that GUI using XNA.