Get ACTUAL full virtual desktop size?

[BarryG]

It turns out that "GetSystemMetrics_(#SM_CXVIRTUALSCREEN)" and the "CY" version don't actually get the entire desktop area when using multiple monitors. Seen lots of posts on StackOverflow about it.

I need to get the entire actual desktop size, regardless of which monitor is set as the main one.

So I tried adapting this code by Chi -> viewtopic.php?p=507541#p507541

And here's what I'm testing:

Code: Select all

; Get full real desktop size of all monitors combined.

Global desktop_size_x,desktop_size_y,desktop_size_w,desktop_size_h

Procedure MonitorEnumProc(hMonitor,hdcMonitor,lprcMonitor,dwData) ; http://forums.purebasic.com/english/viewtopic.php?p=507541
  *monRect.RECT=lprcMonitor
  x=*monRect\left : If x<desktop_size_x : desktop_size_x=x : EndIf
  y=*monRect\top : If y<desktop_size_y : desktop_size_y=y : EndIf
  w=*monRect\right : If w>desktop_size_w : desktop_size_w=w : EndIf
  h=*monRect\bottom : If h>desktop_size_h : desktop_size_h=h : EndIf
  ProcedureReturn #True
EndProcedure

Procedure GetDesktopSize()
  desktop_size_x=0
  desktop_size_y=0
  desktop_size_w=0
  desktop_size_h=0
  EnumDisplayMonitors_(0,0,@MonitorEnumProc(),0)
EndProcedure

GetDesktopSize()

OpenWindow(0,desktop_size_x+10,desktop_size_y+10,desktop_size_w-20,desktop_size_h-20,"",#PB_Window_BorderLess)
SetWindowColor(0,#Yellow)
UpdateWindow_(WindowID(0))
Repeat : WaitWindowEvent(1) : Until GetAsyncKeyState_(#VK_ESCAPE) & $8000 <> 0

When I run this, the yellow window doesn't match the desktop size because monitor 3 on the right is the main one, but it also doesn't work if I set monitor 1 or 2 as the main. Anyone know how to resolve this so that the yellow window fills all 3 monitors? And don't forget to test when all 3 monitors are stacked vertically, too. Thanks.

Screenshot for reference:

[Axolotl]

I cannot test this, because I only have a single monitor setting.
I know, that the GetSystemMetrics() returns a LONG value, so to get the negative values you should do something like below.
Recently I did this.
Maybe you can give it a try and a small feedback.
And sorry in advance, because I do things simple i.e. never did this dpi stuff.

Code: Select all

Procedure.l GetSystemMetrics(Index)   ; .l is important (works in 64-bit) .. variable can be a .i type, index == i.e. #SM_XVIRTUALSCREEN 
  ProcedureReturn GetSystemMetrics_(Index)  ; return depends on Index, i.e. #SM_XVIRTUALSCREEN 
EndProcedure 

Macro VirtualScreenX() 
  GetSystemMetrics(#SM_XVIRTUALSCREEN) 
EndMacro 

Macro VirtualScreenY() 
  GetSystemMetrics(#SM_YVIRTUALSCREEN) 
EndMacro 

Macro VirtualScreenWidth() 
  GetSystemMetrics(#SM_CXVIRTUALSCREEN) 
EndMacro 

Macro VirtualScreenHeight() 
  GetSystemMetrics(#SM_CYVIRTUALSCREEN) 
EndMacro 

Macro CountMonitors() 
  GetSystemMetrics(#SM_CMONITORS) 
EndMacro 

Macro SameDisplayFormat() 
  GetSystemMetrics(#SM_SAMEDISPLAYFORMAT) 
EndMacro 

Macro MonitorAsString()  ; returns <Number of Monitors> _ <entire width> x <entire height>  i.e. '1_1920x1080' 
  Str(GetSystemMetrics(#SM_CMONITORS)) + "_" + Str(GetSystemMetrics(#SM_CXVIRTUALSCREEN)) + "x" + Str(GetSystemMetrics(#SM_CYVIRTUALSCREEN)) 
EndMacro 

[ChrisR]

I haven't tested it, I only have one monitor at the moment.
It seems that there is confusion in your code between: *monRect\right, bottom and Width, Height
desktop_size.. should be a Rect structure. Not tested and don't know if Windows lets you stretch it over several monitors but try with:

Code: Select all

; Get full real desktop size of all monitors combined.
Global desktopRect.Rect

Procedure MonitorEnumProc(hMonitor,hdcMonitor,*monRect.RECT,dwData) ; https://www.purebasic.fr/english/viewtopic.php?p=507541
  If *monRect\left   < desktopRect\left   : desktopRect\left   = *monRect\left   : EndIf
  If *monRect\top    < desktopRect\top    : desktopRect\top    = *monRect\top    : EndIf
  If *monRect\right  > desktopRect\right  : desktopRect\right  = *monRect\right  : EndIf
  If *monRect\bottom > desktopRect\bottom : desktopRect\bottom = *monRect\bottom : EndIf
  ProcedureReturn #True
EndProcedure

Procedure GetDesktopSize()
  desktopRect\left   = 9999
  desktopRect\top    = 9999
  desktopRect\right  = 0
  desktopRect\bottom = 0
  EnumDisplayMonitors_(0,0,@MonitorEnumProc(),0)
EndProcedure

GetDesktopSize()

OpenWindow(0,desktopRect\left+10,desktopRect\top+10,desktopRect\right-desktopRect\left-20,desktopRect\bottom-desktopRect\top-20,"",#PB_Window_BorderLess)
SetWindowColor(0,#Yellow)
UpdateWindow_(WindowID(0))
Repeat : WaitWindowEvent(1) : Until GetAsyncKeyState_(#VK_ESCAPE) & $8000 <> 0

[BarryG]

@Axolotl: No, using #SM_CXVIRTUALSCREEN doesn't work when the monitors are re-arranged.

@ChrisR: Yes, that did it! Thank you so much.

[NicTheQuick]

This also works on Linux:

Code: Select all

Structure DesktopRect
	left.i
	top.i
	right.i
	bottom.i
EndStructure

Procedure.i min(a.i, b.i)
	If a < b: ProcedureReturn a: Else: ProcedureReturn b: EndIf
EndProcedure
Procedure.i max(a.i, b.i)
	If a > b: ProcedureReturn a: Else: ProcedureReturn b: EndIf
EndProcedure

Procedure GetDesktopRect(*rect.DesktopRect)
	Protected i.i, desktops.i = ExamineDesktops()
	With *rect
		\left = $7FFFFFFF 
		\top = $7FFFFFFF
		\right = -$80000000
		\bottom = -$80000000
		For i = 0 To desktops - 1
			\left = min(\left, DesktopX(i))
			\top = min(\left, DesktopY(i))
			\right = max(\right, DesktopX(i) + DesktopWidth(i))
			\bottom = max(\bottom, DesktopY(i) + DesktopHeight(i))
		Next
	EndWith
EndProcedure

Define rect.DesktopRect
GetDesktopRect(rect)
Debug rect\left
Debug rect\top
Debug rect\right
Debug rect\bottom

OpenWindow(0, rect\left, rect\top, rect\right - rect\left, rect\bottom - rect\top, "test", #PB_Window_BorderLess)
Repeat: Until WaitWindowEvent() = #PB_Event_CloseWindow

Or did I miss something?

[moulder61]

@NicTheQuick

Works on my dual monitor Void Linux install except the window opens at what would be 1920,0 rather than 0,0.
The window is sized correctly at 3840,1080, but half of it disappears off the right hand side of the desktop.

I'll check it later in Arch, Devuan and Antix to see if they behave the same?

Moulder.

[moulder61]

@NicTheQuick

If you're interested, Devuan, Arch and Antix all behave the same as Void on my machine re: my previous post.
I don't run a "normal" desktop environment as such. All my installs have the same customised minimal XFWM setup.
Don't know if that would make a difference?

Moulder.

[ChrisR]

Or did I miss something?

You haven't missed any thing, it should work fine with the Desktop library.
Well, maybe you forgot to lock Alt-Tab and Ctrl-Alt-Del shortcuts so as not to close this borderless window