Draw Rectangle directly on the screen without a window?

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upsurt

Joined: 14 Jan 2014
Posts: 51

upsurt

How can I draw a rectangle directly on the screen without a window?

26 Jul 2014, 19:44

cod3b453

Joined: 25 Aug 2004
Posts: 619

cod3b453

You can use GetDesktopWindow and GetWindowDC then the usual drawing functions - SetPixel/LineTo & MoveTo, BitBlt etc but these will not persist without trapping/forcing redraw.

26 Jul 2014, 20:01

upsurt

Joined: 14 Jan 2014
Posts: 51

upsurt

Thank you very much, cod3b453!

Here my first try

Code:

include "win32ax.inc"

.data
  cnt dd 1000

.code 
start:

@@:
  dec [cnt]
  jz @f

  invoke GetDesktopWindow
  invoke GetWindowDC,eax

  invoke BitBlt,eax,100,100,250,100,0,0,0,BLACKNESS

  invoke Sleep,10
  jmp @b
@@:

finish:
  invoke ExitProcess,0

.end start

26 Jul 2014, 21:17

upsurt

Joined: 14 Jan 2014
Posts: 51

upsurt

How can I remove the rectangle and how can I define the color? *confused*

If I move the rectangle to a new position, the old rectangle still exists for some time.

Code:

include "win32ax.inc" 

.data 
  cnt dd 1000 

.code  
start: 

@@: 
  dec [cnt] 
  jz @f 

  invoke GetDesktopWindow 
  invoke GetWindowDC,eax 

  invoke BitBlt,eax,[cnt],[cnt],250,100,0,0,0,BLACKNESS 

  invoke Sleep,10 
  jmp @b 
@@: 

finish: 
  invoke ExitProcess,0 

.end start

26 Jul 2014, 21:25

cod3b453

Joined: 25 Aug 2004
Posts: 619

cod3b453

The problem here is you are effectively hijacking the screen and overwriting the display area; if you really want to do this without creating a proper window you'll either need to enumerate all the open windows using EnumWindows* or save a copy of the screen under the region you're colouring in and put it back when you move it (though this is less reliable).

*You can get their regions using GetWindowRect. For every window that is under your box, you'll probably need to trap drawing using SetWindowLong to subclass the WM_PAINT or similar messages to redraw over the top or use SendMessage WM_PAINT or similar to force a redraw when you want to move it and restore the proper drawing.

26 Jul 2014, 21:42

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 17933
Location: In your JS exploiting you and your system

revolution

You could also force all other windows to redraw the portion under the rectangle by sending an InvalidateRect message. That way you don't need to manage the pixels yourself, each window will handle its own drawing in the usual fashion.

26 Jul 2014, 21:59

cod3b453

Joined: 25 Aug 2004
Posts: 619

cod3b453

revolution wrote:

...InvalidateRect...

I knew it existed! Just couldn't remember the name Cool

26 Jul 2014, 22:05

upsurt

Joined: 14 Jan 2014
Posts: 51

upsurt

Thank you, guys! You're awesome!

27 Jul 2014, 08:46

upsurt

Joined: 14 Jan 2014
Posts: 51

upsurt

AndreyT wrote:

InvalidateRect does not immediately redraw the window. It simply "schedules" a future redraw for a specific rectangular area of the window. Using InvalidateRect you may schedule as many areas as you want, making them accumulate in some internal buffer. The actual redrawing for all accumulated scheduled areas will take place later, when the window has nothing else to do. (Of course, if the window is idle at the moment when you issue the InvalidateRect call, the redrawing will take place immediately).

You can also force an immediate redraw for all currently accumulated invalidated areas by calling UpdateWindow. But, again, if you are not in a hurry, explicitly calling UpdateWindow is not necessary, since once the window is idle it will perform a redraw for all currently invalidated areas automatically.

RedrawWindow, on the other hand, is a function with a much wider and flexible set of capabilities. It can be used to perform invalidation scheduling (i.e. the same thing InvalidateRect does) or it can be used to forcefully perform immediate redrawing of the specified area, without doing any "scheduling". In the latter case calling RedrawWindow is virtually equivalent to calling InvalidateRect and then immediately calling UpdateWindow.

Source: http://stackoverflow.com/questions/2325894/difference-between-invalidaterect-and-redrawwindow

28 Jul 2014, 14:06

badc0de02

Joined: 25 Nov 2013
Posts: 216
Location: %x

badc0de02

you have to make a screen shot and copy from the image the rect and set it in like a puzzle to remove it --

28 Jul 2014, 16:04

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 17933
Location: In your JS exploiting you and your system

revolution

A screen shot is not a good option IMO because the applications running can be dynamic and have different data to display. If you simply overwrite it with some previous capture then you get old pixels mixed with new pixels and the user says "WTF is this mess?".

28 Jul 2014, 16:39

badc0de02

Joined: 25 Nov 2013
Posts: 216
Location: %x

badc0de02

so just simply use window hook to update every windows SIMPLY?

28 Jul 2014, 17:20

badc0de02

Joined: 25 Nov 2013
Posts: 216
Location: %x

badc0de02

or just simply get A new Screenshot to every drawing cycle and REPLACE IT SIMPLY?

28 Jul 2014, 17:22

badc0de02

Joined: 25 Nov 2013
Posts: 216
Location: %x

badc0de02

we have now to opinions Revolution wich is the simplest wich no?

28 Jul 2014, 17:25

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 17933
Location: In your JS exploiting you and your system

revolution

badc0de02 wrote:

or just simply get A new Screenshot to every drawing cycle and REPLACE IT SIMPLY?

A new screen shot would have the rectangle on it thus defeating the purpose.

28 Jul 2014, 17:46

badc0de02

Joined: 25 Nov 2013
Posts: 216
Location: %x

badc0de02

whats with the next OPINION?

28 Jul 2014, 17:55

upsurt

Joined: 14 Jan 2014
Posts: 51

upsurt

I thought also about screenshots ... but wasn't sure about the overhead/data while making a mass of screenshots.

And by the way, how would I paint the rectangle part of the image to the screen?
The code I've right now draws only a black rectangle. And I don't know how to change the color.
I guess it should also be able to draw a circle ... without painting every single by my self.

28 Jul 2014, 18:47

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 17933
Location: In your JS exploiting you and your system

revolution

upsurt wrote:

And by the way, how would I paint the rectangle part of the image to the screen?

If you want to transfer an image then you can use the BitBlt API.

BTW: I can't image why you want to avoid using a window. Things become much simpler when you use the OS tools for their intended purpose. The OS can also use the GPU to accelerate various functions. If you bypass all that stuff then you probably only end up creating a headache for yourself by duplicating all the OS code.

28 Jul 2014, 18:55

upsurt

Joined: 14 Jan 2014
Posts: 51

upsurt

upsurt wrote:

AndreyT wrote:

InvalidateRect does not immediately redraw the window. It simply "schedules" a future redraw for a specific rectangular area of the window. Using InvalidateRect you may schedule as many areas as you want, making them accumulate in some internal buffer. The actual redrawing for all accumulated scheduled areas will take place later, when the window has nothing else to do. (Of course, if the window is idle at the moment when you issue the InvalidateRect call, the redrawing will take place immediately).

You can also force an immediate redraw for all currently accumulated invalidated areas by calling UpdateWindow. But, again, if you are not in a hurry, explicitly calling UpdateWindow is not necessary, since once the window is idle it will perform a redraw for all currently invalidated areas automatically.

RedrawWindow, on the other hand, is a function with a much wider and flexible set of capabilities. It can be used to perform invalidation scheduling (i.e. the same thing InvalidateRect does) or it can be used to forcefully perform immediate redrawing of the specified area, without doing any "scheduling". In the latter case calling RedrawWindow is virtually equivalent to calling InvalidateRect and then immediately calling UpdateWindow.

Source: http://stackoverflow.com/questions/2325894/difference-between-invalidaterect-and-redrawwindow

by the way, these to options work, but only around 80%

invoke InvalidateRect,rc,TRUE
invoke UpdateWindow,[hwnd]

and

invoke RedrawWindow,[hwnd],NULL,NULL,RDW_FRAME+RDW_INVALIDATE+RDW_UPDATENOW+RDW_ALLCHILDREN

But they don't clean the whole rectangle, only a part. So they will be a black part left. Sad

WHY??

28 Jul 2014, 18:55

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 17933
Location: In your JS exploiting you and your system

revolution

upsurt wrote:

<snip>

But they don't clean the whole rectangle, only a part. So they will be a black part left.

WHY??

Because the OS uses a lot of optimisations to make things more efficient. But when you do thing manually without informing the OS about changes then things get out of sync.

BTW: If you used a formal window then you won't have this problem.

28 Jul 2014, 18:58

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