Mega Code Archive
Cleaning up EnumWindows
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Title: Cleaning up EnumWindows.
Question: I`ve seen how to use EnumWindows to get a list of all the current windows - but I get back a bunch of blanks and things I`ve never heard of. What`s going on?
Answer:
The follwoing appiles to Win95, 98 and NT - I have no idea if it works on 2000.
EnumWindows and it's callback EnumWndProc don't pull pack the handles of all the forms running, it pulls back all the handles of the Windowed Controlls ( i.e., forms, Editboxes, Memos, ect.) So, if your tring to use EnumWindows to find all the open forms on a system, you have to seperate the wheat from the chaff, so to speak.
To do this, I've found that two API functions, IsChild and GetClassName work well. IsChild Compares two Handles and returns weather or not the second is the child of the first. This should rid your list of most of the EditBoxes, Memos ect. GetClassName returns the class name of a Windowed Object - i.e., TForm TEditBox, ect. (Please note: this is often returned as the Windows class name or the C Class name, depending apon what language the App was developed under.)
Here's the prototypes for these functions:
Function GetClassName(
hWnd : THandle; // handle of window
lpClassName : PChar; // buffer for class name
nMaxCount : Integer; // size of buffer, in characters
) : integer; // Returns number of Characters copied, 0 = an Error
Function IsChild(
parWhnd : THandle; // Handle of Parent Object
ChdWhnd : THandle; // Handle of Child Object
) : Boolean; // Returns True if ParWhnd is the Parent of ChdWhnd
Don't worry - There both in the Windows Unit.
The following code impiments this methodology - Please pay close attention to the scope that the variables are in. It's supper touchy because of the callback.
Uses Windows;
Interface
type THandleArray = Array of THandle;
Procedure GetWindows( out WindowList : THandleArray; out Count : Integer; BadClassName : String);
Implimentation
var Wind : THandleList; //Temporary Storage of the Handles
var WinCount : Integer; //Temporary Counter
Function EnumWndProc(hwnd : THandle; Param : Cardinal) : Boolean; export; StdCall;
begin
// Remember - this function loops through for every window
Result := True; //Get The next Handle
winCount := WinCount + 1; //Increase the count
SetLength(Wind, winCount); //Expand the Dynamic Array
Wind[(WinCOunt - 1)] := hwnd; // Set the handle into the Temp Storage
end;
Procedure GetWindows( out WindowList : THandleArray; out Count : Integer; BadClassName : String);
var I, II, Count : Integer;
var AddWin : Boolean;
var Classname : String;
begin
winCount := 0; /Set The Count to 0
EnumWindows(@EnumWndProc, 0); // Start the loop through WnumWndProc
Count := 0;
for I := 0 to (WinCount - 1) do
Begin
AddWin := True; // Set The Add Flag to true
GetClassName(Wind[I], PChar(ClassName), 255) // get the class name
ClassName := PChar(ClassName); //Reformat the classname
If Lowercase(ClassName) = Lowercase(BadClassName)
then AddWin := False; // set flag acordingly
for II := 0 to (WinCOunt - 1) do
begin
if I II then // Don't check yourself!
begin
if ((Wind[I] = Wind[II]) or (isChild(Wind[II], Wind[I]))
then AddWin := False; // check for children and dups
end;
end;
if AddWin = True then
begin
Count := Count + 1;
SetLength(tempList, Count);
tempList[(Count - 1)] := Wind[I];
end;
end;
end;
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