VB API First Lesson GETDC call

function function:

The GetDC function user obtains the device environment handle for the client area or entire screen of the specified window, and then you can use the handle in the GDI function to draw in the device environment.

A device environment is an undisclosed data structure whose values are used internally by GDI functions.

Gets the handle of the device called GetDC, first declares

Private Declare Function GetDC Lib "user32" (ByVal hwnd as long) as long

Parameter resolution:

Parameters	Meaning
HWnd	1. The specified window handle 2. If the value is NULL, get the entire screen of the device environment

return value:

1. If the function call succeeds, the return value is the device environment handle for the client area of the specified window;

2. If the function call fails, the return value is NULL.

Example

Get the device handle for a form

Option Explicit

Private Declare Function GetDC Lib "user32" (ByVal hwnd as long) as long

Private Sub Command1_Click ()
Dim Formhdc as Long
FORMHDC = GetDC (Form1.hwnd)
Print FORMHDC
End Sub

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VB API First Lesson GETDC call