Oxygen Basic
Programming => Bugs & Feature Requests => Topic started by: Nicola on October 06, 2020, 06:48:39 AM
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Hi,
A question.
Could I read the color of a pixel outside of a specific window, Without specifying the handle of the specific window or object?
thanks
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I think you get the hDC of the whole screen by setting the Window handle as null:
A C snippet from this page:
https://stackoverflow.com/questions/2659932/how-to-read-the-screen-pixels
HDC hdcScreen = ::GetDC(NULL);
COLORREF pixel = ::GetPixel(hdcScreen, x, y);
ReleaseDC(NULL, hdcScreen);
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Unfortunately, there are some very strange offsets when trying to read a screen pixel (using GetPixel). Perhaps you can make sense of it.
uses corewin
% ID_Timer 3000
% Interval 100
dim cmdline as asciiz ptr,inst as sys
&cmdline=GetCommandLine
inst=GetModuleHandle 0
'
'
function WndProc (sys hWnd,wMsg,wParam,lparam) as sys callback
==============================================================
static as sys hdc, htimer
static as String txt
static as RECT crect
static as PAINTSTRUCT Paintst
static as POINT p
static as int pix
'==========
select wMsg
'==========
case WM_CREATE
static sys hDCs=GetDC 0
hTimer = SetTimer (hWnd, ID_Timer, 100, 0)
GetClientRect hWnd,&cRect
case WM_TIMER
GetCursorPos @p
pix=GetPixel(hDCs,p.x, p.y)
InvalidateRect hwnd,&crect, 1
case WM_DESTROY
ReleaseDC hDCs
KillTimer(hWnd,ID_TIMER)
PostQuitMessage 0
case WM_PAINT
hDC=BeginPaint hWnd,&Paintst
GetClientRect hWnd,&cRect
'style
'0x20 DT_SINGLELINE
'0x04 DT_VCENTER
'0x01 DT_CENTER
'0x25
SetBkColor hdc,pix
SetTextColor hdc,0
txt="x y color " str(p.x) " , " str(p.y) " , " hex(pix,4)
DrawText hDC,strptr txt,-1,&cRect,0x25
EndPaint hWnd,&Paintst
ValidateRect hwnd,&crect
case WM_KEYDOWN
Select wParam
Case 27 : SendMessage hwnd, WM_CLOSE, 0, 0 'ESCAPE
End Select
'
InvalidateRect hwnd, &cRect, 1 'FULL SCREEN REFRESH
case else
function=DefWindowProc hWnd,wMsg,wParam,lParam
end select
end function ' WndProc
Function WinMain(sys inst,prevInst,zstring*cmdline,sys show) as sys
===================================================================
WndClass wc
MSG wm
sys hwnd, wwd, wht, wtx, wty, tax
wc.style = CS_HREDRAW or CS_VREDRAW
wc.lpfnWndProc = @WndProc
wc.cbClsExtra =0
wc.cbWndExtra =0
wc.hInstance =inst
wc.hIcon=LoadIcon 0, IDI_APPLICATION
wc.hCursor=LoadCursor 0,IDC_ARROW
wc.hbrBackground = GetStockObject WHITE_BRUSH
wc.lpszMenuName =0
wc.lpszClassName = strptr "Demo"
RegisterClass (&wc)
Wwd = 400 : Wht = 200
Tax = GetSystemMetrics SM_CXSCREEN
Wtx = (Tax - Wwd) /2
Tax = GetSystemMetrics SM_CYSCREEN
Wty = (Tax - Wht) /2
hwnd = CreateWindowEx 0,wc.lpszClassName,"OXYGEN BASIC",WS_OVERLAPPEDWINDOW,Wtx,Wty,Wwd,Wht,0,0,inst,0
ShowWindow hwnd,SW_SHOW
UpdateWindow hwnd
'
sys bRet
'
do while bRet := GetMessage (@wm, 0, 0, 0)
if bret=0
exit while
end if
if bRet = -1
'show an error message
exit while
else
TranslateMessage @wm
DispatchMessage @wm
end if
end while
End Function
WinMain inst,0,cmdline,SW_NORMAL
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The x-coordinate, in logical units, of the pixel to be examined.
How does that differ from pixel count position?
Is GetPixel DPI aware?
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Hi Charles.
Your program works great. Very well done. Although, for me as a beginner at O2, there are so many instructions that are new.
... if I wanted to create an external function, to put in an .inc file, could it be done?
As for the value of the DPI, it seems to me that there may be problems.
However, you are great. ;)
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Hi Nicola, :)
You can put any source code you like into an inc file. But declared functions for accessing DLLs need to be within an extern block
On rhe other side, when making DLLs, the exported functions need to go in an extern export block, or be individually tagged 'export'
Some DLL demos in examples\DLLs.