How to draw an image in the middle of the screen and have it for 300 ms and then hide it?

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I'm making a subliminal images program for me and to put it for free online, I want the pics to show fast on the screen (say one every 5 seconds, for the duration of 300 ms), I know how to do all except that the way I know to draw on the screen doesn't have another way of removing what the program drew on the screen and showing what was behind it except by redrawing the whole screen, also I want that if the user clicked by mistake a mouse click on the image which appears and fades fast, the program doesn't take the mouse click and passes it down to the thing in screen just below it.

If I make a borderless form it would take the mouse clicks and maybe the keyboard focus (maybe I can make it not able to be focused on as I remember maybe there's a way)

What I have tried:

C#

[DllImport("User32.dll")]
public static extern IntPtr GetDC(IntPtr hwnd);
[DllImport("User32.dll")]
public static extern void ReleaseDC(IntPtr hwnd, IntPtr dc);
//Get a Graphics object for the entire screen and draw a rectangle with it:
[DllImport("user32.dll")]
public static extern bool InvalidateRect(IntPtr hwnd, IntPtr lpRect, bool bErase);


IntPtr desktopPtr;
Graphics g;

            desktopPtr = GetDC(IntPtr.Zero);
            g = Graphics.FromHdc(desktopPtr);
            g.DrawImage(...)
            Thread.Sleep(300);
            InvalidateRect(IntPtr.Zero, IntPtr.Zero, true);

I solved it, but this draws the pic on the screen very slowly from top to bottom and I want an instant drawing of it...

I need to pass the mouse click down to the next windows just below it if the user mouse clicks on the form by mistake, the form gets closed immediately and the mouse click should be ordered in that exact place, this is for knowing the scaling factor of the display to order the mouse click in the correct position:

private float getScalingFactor()
{
Graphics g = Graphics.FromHwnd(IntPtr.Zero);
IntPtr desktop = g.GetHdc();
int LogicalScreenHeight = GetDeviceCaps(desktop, (int)DeviceCap.VERTRES);
int PhysicalScreenHeight = GetDeviceCaps(desktop, (int)DeviceCap.DESKTOPVERTRES);

float ScreenScalingFactor = (float)PhysicalScreenHeight / (float)LogicalScreenHeight;

return ScreenScalingFactor; // 1.25 = 125%
}

[DllImport("gdi32.dll")]
static extern int GetDeviceCaps(IntPtr hdc, int nIndex);

public enum DeviceCap
{
VERTRES = 10,
DESKTOPVERTRES = 117,

// http://pinvoke.net/default.aspx/gdi32/GetDeviceCaps.html
}

whether it's a right or left or middle click should be taken in consideration too.

Posted 11-Oct-21 5:52am

john1990_1

Updated 12-Oct-21 13:14pm

v13

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PIEBALDconsult 11-Oct-21 18:59pm

Is that what your customers want?

john1990_1 11-Oct-21 19:04pm

No, I need the pic to be drawn on the screen efficiently and not be drawn slowly from top to bottom, I made a borderless form which is another solution but it takes keyboard focus and consumes mouse clicks, is there a way to make a borderless form that can't get focus and doesn't "eat" mouse clicks and lets them go to the window just below it?

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OriginalGriff · Answer 1 · 2021-10-11T20:54:00

Solution 1

Draw your images into Bitmaps so they are "ready to go" (you may have this already) and save them in a collection like a List.

Then create a UserControl based on a Picturebox, and add a Timer to the Picturebox in the Show event handler. handle the Tick event.
Add a "showing" flag to your control.
Add your own property called Images, which accepts the List of Images. When it is set, call a method to display an image.
In the show method call a method called DisplayImage.

In DisplayImage:
Set the Showing flag to true.
Set the Timer.Interval property to 300
Select an Image from the List, and set the controls Image property to the image. Set up for the next one.
Start the Timer.

In the Tick handler:
Check the Showing flag
If it's true, clear it, set the Interval to 5000, and clear the Image property.
Otherwise, set it, and call DisplayImage.

Then just add the control to your form, and set the Images property to your collection.

Posted 11-Oct-21 20:54pm

OriginalGriff

Comments

john1990_1 12-Oct-21 11:16am

Thx, all this I already did, I put the images in "Image" not "Bitmap" one file each time and show the form only on LoadComplete of the pictrurebox, so it's the same, the only problem is that if the user presses with a mouse and the form appears so he presses on the form by mistake the click gets eaten, I think in that case I would close the form and order a mouse click on that exact location, how can this be done with taking into account display zoom scale ratio?

john1990_1 12-Oct-21 11:22am

I added to the question.

Dave Kreskowiak 12-Oct-21 12:58pm

I think he's trying to do this as an "overlay" on top of the Desktop and other applications?

john1990_1 12-Oct-21 12:59pm

Dave would you please explain?

Dave Kreskowiak 12-Oct-21 13:00pm

Me? No, YOU have to explain what you're trying to do.

john1990_1 12-Oct-21 13:04pm

I now just need a way to: If the user pressed on the "pic form" by mistake that appears on the desktop as a topmost window to show him pics fast for his subliminal brain, I want my form to get closed immediately (which I know how to do) and pass the mouse click to the form just below it, with a mouse click order, which I know how to do but not if the screen display scale is not 100% (125% or 150% or 175%...), I don't know how to locate the mouse press if the scale is not 100% and how to order a mouse click just where it was.

Dave Kreskowiak 12-Oct-21 13:06pm

You're overcomplicating this.

WHy not just make your form "transparent" to the mouse clicks instead?

https://www.codeproject.com/Articles/12877/Transparent-Click-Through-Forms

john1990_1 12-Oct-21 13:34pm

Thx but this is in VB and I want C# and it seems so much beyond my ability, would you please make it simpler? and another problem I detected now is that I don't want the keyboard focus to go to it so do you know how to do this plz?

Dave Kreskowiak 12-Oct-21 13:35pm

So? THey both target the same framework. VB.NET and C# are very much alike. It's easy to translate.

There's even online converters for it.

Or, you can read what's going on in the code and write the equivalent code yourself.

john1990_1 12-Oct-21 13:54pm

Thx, what about the form not getting keyboard focus?

Dave Kreskowiak 12-Oct-21 14:00pm

One thing at a time. Get the form working how you want it to display.

Disabling focus is relatively easy.

john1990_1 12-Oct-21 14:01pm

I think it's severely hard for me to do the mouse click transparency now, from easy to hard, how to disable keyboard focus plz?

Dave Kreskowiak 12-Oct-21 15:44pm

What do you mean "hard"? You're already doing everything you need in your existing code you posted. The hardest thing in there is declaring the external function calls, which you're already doing something very similar, and I've already laid out the functions to call and their parameters and types.

Turning off focus is easy. You just have to override your Form's WndProc method and ignore passing on a certain message to the base WndProc method. But, you do NOT want to do this until you get everything else working because that would prevent you from doing anything in your form.

private const int WM_SETFOCUS = 0x0007;

protected override void WndProc(ref Message m)
{
    if (m.Msg != WM_SETFOCUS)
    {
        base.WndProc(ref m);
    }
}

It pisses me off that people like you don't want to try stuff and experiment with code and that is exactly what you need to be able to do to figure this stuff out.

If you're not willing to do that, give up writing code right now.