Develop Reference

Making Background Transparent

I am trying to make a makeshift onscreen keyboard for Windows 10 and need the background to be transparent, to make it more convenient for the user (the keys are already transparent). I, however, have no idea how to make the background transparent.
Any help would be greatly appreciated.
I believe that I am essentially looking for an updated version of the code in this thread show below:
using System;
using System.Runtime.InteropServices;
using UnityEngine;
public class TransparentWindow : MonoBehaviour
{
[SerializeField]
private Material m_Material;
private struct MARGINS
{
public int cxLeftWidth;
public int cxRightWidth;
public int cyTopHeight;
public int cyBottomHeight;
}
[DllImport("user32.dll")]
private static extern IntPtr GetActiveWindow();
[DllImport("user32.dll")]
private static extern int SetWindowLong(IntPtr hWnd, int nIndex, uint dwNewLong);
[DllImport("user32.dll")]
static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);
[DllImport("user32.dll", EntryPoint = "SetLayeredWindowAttributes")]
static extern int SetLayeredWindowAttributes(IntPtr hwnd, int crKey, byte bAlpha, int dwFlags);
[DllImport("user32.dll", EntryPoint = "SetWindowPos")]
private static extern int SetWindowPos(IntPtr hwnd, int hwndInsertAfter, int x, int y, int cx, int cy, int uFlags);
[DllImport("Dwmapi.dll")]
private static extern uint DwmExtendFrameIntoClientArea(IntPtr hWnd, ref MARGINS margins);
const int GWL_STYLE = -16;
const uint WS_POPUP = 0x80000000;
const uint WS_VISIBLE = 0x10000000;
const int HWND_TOPMOST = -1;
void Start()
{
// You really don't want to enable this in the editor, but it works there..
int fWidth = Screen.width;
int fHeight = Screen.height;
var margins = new MARGINS() { cxLeftWidth = -1 };
var hwnd = GetActiveWindow();
SetWindowLong(hwnd, GWL_STYLE, WS_POPUP | WS_VISIBLE);
// Transparent windows with click through
SetWindowLong(hwnd, -20, 524288 | 32);//GWL_EXSTYLE=-20; WS_EX_LAYERED=524288=&h80000, WS_EX_TRANSPARENT=32=0x00000020L
SetLayeredWindowAttributes(hwnd, 0, 255, 2);// Transparency=51=20%, LWA_ALPHA=2
SetWindowPos(hwnd, HWND_TOPMOST, 0, 0, fWidth, fHeight, 32 | 64); //SWP_FRAMECHANGED = 0x0020 (32); //SWP_SHOWWINDOW = 0x0040 (64)
DwmExtendFrameIntoClientArea(hwnd, ref margins);
}
void OnRenderImage(RenderTexture from, RenderTexture to)
{
Graphics.Blit(from, to, m_Material);
}
}
The code given did not work, so I assume that it is outdated. I have no idea how to update it myself, since it is a bit out of my skill set. When I upload the code to Unity, it just says that there are errors in the code and that it is not a valid script. When I open the script, however, no errors appear.
I expect to be able to have a relatively good view of whatever is behind my keyboard, like my desktop, but I actually just see a black plane.
Update:
So apparently the error message was caused by my script not having the same name as my class. I spent over 4 hours yesterday trying to fix that error message, and this naming incident was the cause :(. Thanks Ruzihm. Anyway, now that the error message is gone, when I run or build the program, my transparent window material just comes up: a dark pink. I then changed my Unity version back to 2018.2.16f1, with no success. Then I removed the #if !Unity Editor line to get the transparency to work perfectly in the editor, but not when I build it. Note, click through does work when I build it and when I run it in the editor.

As discovered in the comments, the problem was fixed when the camera's clear flags were set to solid color and the pink transparent window material was replaced a with white transparent material.

"Place" a WinForm directly on the desktop

So I want to have something similar to an desktop overlay. So the thing is I tried to draw to the desktop wallpaper directly but this will get redrawn and from what I read there is really no good way around this. So I tried to go with a broderless completely transparent WinForm with text on it.
The Problem I have with is that hitting Windows+D will hide the application and I didn't found a way to prevent this or bring it up again. Also I read that setting the form as a Child of the Desktop can cause problems aswell.
What I did so far was setting the position of the Form directly above the Desktop:
[DllImport("user32.dll")]
static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
static readonly IntPtr HWND_BOTTOM = new IntPtr(1);
const UInt32 SWP_NOSIZE = 0x0001;
const UInt32 SWP_NOMOVE = 0x0002;
const UInt32 SWP_NOACTIVATE = 0x0010;
//By calling SetWindowPos(Handle, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE); it will move to the very back of all windows.
What I want in the end is a Win Form that is always ontop of the Desktop but under every other window.

You should run a thread which in fraction of time ( such as 100ms) call BringWindowToTop api and bring your window aplication to top, it will solve to Win+D issue.
[DllImport("user32.dll", SetLastError=true)]
static extern bool BringWindowToTop(IntPtr hWnd);
[DllImport("user32.dll", SetLastError=true)]
static extern bool BringWindowToTop(HandleRef hWnd);

Can you get the position of a window that is inside of another application

So I found an example from an answer provided here
There was an answer that gave this example of code to move the Notepad window to the top left corner of the screen. I tried it and it worked fine. I then tried it on a small project I am working on and I couldn't move it.
NOTE: I did change the "Notepad" to the name at the top of the window I wanted to move.
using System;
using System.Runtime.InteropServices; // For the P/Invoke signatures.
public static class PositionWindowDemo
{
// P/Invoke declarations.
[DllImport("user32.dll", SetLastError = true)]
static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
[DllImport("user32.dll", SetLastError = true)]
static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
const uint SWP_NOSIZE = 0x0001;
const uint SWP_NOZORDER = 0x0004;
public static void Main()
{
// Find (the first-in-Z-order) Notepad window.
IntPtr hWnd = FindWindow("Notepad", null);
// If found, position it.
if (hWnd != IntPtr.Zero)
{
// Move the window to (0,0) without changing its size or position
// in the Z order.
SetWindowPos(hWnd, IntPtr.Zero, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOZORDER);
}
}
}
I will give an example. Consider Visual Studios and how it has the Solution Explorer Window or the Output window, and I can drag them with the mouse and move them or undock them. Would there be a way to have an application that has windows inside of it similar to Visual Studios and get the position of them in a program?
I have seen many answers on here about moving a window or finding the active window etc. However I am not sure if I will be able to access this subWindow that is inside of another application.
Thanks

Setting position of a application in windows

I have a programm, which calls an extern application. The application is designed to run with 2 monitors. The first programm on monitor 1 and the second at monitor 2.
Now i have the problem that the extern application has no parameter I can give them to enforce raising on the second monitor.
Is there any possability to force another application to chance his position. Also good would be a possability to enforce changing his window state (always start as maximized).

See this instruction from MSDN.
http://msdn.microsoft.com/en-us/library/windows/desktop/dd162827(v=vs.85).aspx
Functions from WinAPI you'll need are
FindWindow - Find the window handle (HWND)
SetWindowPos - Sets the window position
ShowWindow - Change window state
EnumDisplayMonitors - Get monitor information
See pinvoke.net how to import these functions in C#

API can help you achieve same
so start by declaring
[DllImport("user32.dll")]
static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
[DllImport("user32.dll")]
static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);
const int SW_SHOWMAXIMIZED = 3;
const int SWP_FRAMECHANGED = 0x0020;
to use above simply invoke the target app and send it where you want it to and maximize
Process p = Process.Start(new ProcessStartInfo("notepad"));
Thread.Sleep(1000); //depends
IntPtr handle = p.MainWindowHandle;
SetWindowPos(handle, IntPtr.Zero, 200, 200, 500, 600, SWP_FRAMECHANGED);
ShowWindowAsync(handle, SW_SHOWMAXIMIZED);
above example is using notepad, you will choose your app here

Setting a Windows form to be bottommost

Some background
One of my current clients runs a chain of Internet points where customers an access the net through PC:s set up as "kiosks" (a custom-built application "locks" the computer until a user has signed in, and the running account is heavily restricted through the Windows group policy). Currently, each computer is running Windows XP and uses Active Desktop to display advertisements in the background. However, since my client has got problems with Active Desktop crashing on a daily basis (in addition to generally slowing down the computer) I have been asked to develop an application that replaces it.
The problem
I am trying to investigate whether it is possible to build a Windows forms application (using C#) that always stays in the background. The application should lie above the desktop (so that it covers any icons, files etc) but always behind all other running applications. I guess I'm really looking for a BottomMost property of the Form class (which doesn't exist, of course).
Any tips or pointers on how to achieve this would be highly appreciated.

This isn't directly supported by the .NET Form class, so you have two options:
1) Use the Win32 API SetWindowPos function.
pinvoke.net shows how to declare this for use in C#:
[DllImport("user32.dll")]
static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
static readonly IntPtr HWND_BOTTOM = new IntPtr(1);
const UInt32 SWP_NOSIZE = 0x0001;
const UInt32 SWP_NOMOVE = 0x0002;
const UInt32 SWP_NOACTIVATE = 0x0010;
So in your code, call:
SetWindowPos(Handle, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE);
As you commented, this moves the form to the bottom of the z-order but doesn't keep it there. The only workaround I can see for this is to call SetWindowPos from the Form_Load and Form_Activate events. If your application is maximized and the user is unable to move or minimise the form then you might get away with this approach, but it's still something of a hack. Also the user might see a slight "flicker" if the form gets brought to the front of the z-order before the SetWindowPos call gets made.
2) subclass the form, override the WndProc function and intercept the WM_WINDOWPOSCHANGING Windows message, setting the SWP_NOZORDER flag (taken from this page).

I think the best way to do so is using the activated event handler and SendToBack method, like so:
private void Form1_Activated(object sender, EventArgs e)
{
this.SendToBack();
}

Set your window to be a child window of the desktop (the "Program Manager" or "progman" process). I've succeeded with this method in Windows XP (x86) and Windows Vista (x64).
I stumbled on this method while searching for a way to make a screensaver display as if it were wallpaper. It turns out, this is sort of built in to the system's .scr handler. You use screensaver.scr /p PID, where PID is the process id of another program to attach to. So write a program to find progman's handle, then invoke the .scr with that as the /p argument, and you have screensaver wallpaper!
The project I'm playing with now is desktop status display (shows the time, some tasks, mounted disks, etc), and it's built on Strawberry Perl and plain Win32 APIS (mainly the Win32::GUI and Win32::API modules), so the code is easy to port to or understand any dynamic language with similar Win32 API bindings or access to Windows' Scripting Host (eg, ActivePerl, Python, JScript, VBScript). Here's a relevant portion of the class that produces the window:
do { Win32::API->Import(#$_) or die "Win32::API can't import #$_ ($^E)" } for
[user32 => 'HWND FindWindow(LPCTSTR lpClassName, LPCTSTR lpWindowName)'],
[user32 => 'HWND SetParent(HWND hWndChild, HWND hWndNewParent)'],
sub __screen_x {
Win32::GUI::GetSystemMetrics(SM_CXSCREEN)
}
sub __screen_y {
Win32::GUI::GetSystemMetrics(SM_CYSCREEN)
}
sub _create_window { # create window that covers desktop
my $self = shift;
my $wnd = $$self{_wnd} = Win32::GUI::Window->new(
-width => __screen_x(), -left => 0,
-height => __screen_y(), -top => 0,
) or die "can't create window ($^E)";
$wnd->SetWindowLong(GWL_STYLE,
WS_VISIBLE
| WS_POPUP # popup: no caption or border
);
$wnd->SetWindowLong(GWL_EXSTYLE,
WS_EX_NOACTIVATE # noactivate: doesn't activate when clicked
| WS_EX_NOPARENTNOTIFY # noparentnotify: doesn't notify parent window when created or destroyed
| WS_EX_TOOLWINDOW # toolwindow: hide from taskbar
);
SetParent($$wnd{-handle}, # pin window to desktop (bottommost)
(FindWindow('Progman', 'Program Manager') or die "can't find desktop window ($^E)")
) or die "can't pin to desktop ($^E)";
Win32::GUI::DoEvents; # allow sizing and styling to take effect (otherwise DC bitmaps are the wrong size)
}
This program buffers output to prevent flickering, which you'll probably want to do as well. I create a DC (device context) and PaintDesktop to it (you could use any bitmap with only a couple more lines -- CreateCompatibleBitmap, read in a file, and select the bitmap's handle as a brush), then create a holding buffer to keep a clean copy of that background and a working buffer to assemble the pieces -- on each loop, copy in background, then draw lines and brush bitmaps and use TextOut -- which is then copied to the original DC, at which time it appears on screen.

Yes, function SetWindowPos with flag HWND_BOTTOM should help you. But, from my experience: even after calling SetWindowPos as result of some user operations your window may bring to front.

subclass the form, override the WndProc function and intercept the Windows message(s) that are responsible for moving it up the z-order when it gets activated.

Create a Panel that cover your form, but what ever you want on that Panel, then in the Panel's Click-Event write this.sendback .

I've managed to get rid of the flickering when using setwindowpos...
const UInt32 SWP_NOSIZE = 0x0001;
const UInt32 SWP_NOMOVE = 0x0002;
const UInt32 SWP_NOACTIVATE = 0x0010;
const UInt32 SWP_NOZORDER = 0x0004;
const int WM_ACTIVATEAPP = 0x001C;
const int WM_ACTIVATE = 0x0006;
const int WM_SETFOCUS = 0x0007;
static readonly IntPtr HWND_BOTTOM = new IntPtr(1);
const int WM_WINDOWPOSCHANGING = 0x0046;
[DllImport("user32.dll")]
static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X,
int Y, int cx, int cy, uint uFlags);
[DllImport("user32.dll")]
static extern IntPtr DeferWindowPos(IntPtr hWinPosInfo, IntPtr hWnd,
IntPtr hWndInsertAfter, int x, int y, int cx, int cy, uint uFlags);
[DllImport("user32.dll")]
static extern IntPtr BeginDeferWindowPos(int nNumWindows);
[DllImport("user32.dll")]
static extern bool EndDeferWindowPos(IntPtr hWinPosInfo);
private void Window_Loaded(object sender, RoutedEventArgs e)
{
IntPtr hWnd = new WindowInteropHelper(this).Handle;
SetWindowPos(hWnd, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
IntPtr windowHandle = (new WindowInteropHelper(this)).Handle;
HwndSource src = HwndSource.FromHwnd(windowHandle);
src.AddHook(new HwndSourceHook(WndProc));
}
private IntPtr WndProc(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
if (msg == WM_SETFOCUS)
{
IntPtr hWnd = new WindowInteropHelper(this).Handle;
SetWindowPos(hWnd, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
handled = true;
}
return IntPtr.Zero;
}
private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
IntPtr windowHandle = (new WindowInteropHelper(this)).Handle;
HwndSource src = HwndSource.FromHwnd(windowHandle);
src.RemoveHook(new HwndSourceHook(this.WndProc));
}