Mega Code Archive
Creating two horizontal lines on your screen (TDesktopCanvas)
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Title: Creating two horizontal lines on your screen? (TDesktopCanvas)
Question: How do I create lines (or whatever) on the screen?
Eg. TDesktopCanvas
Answer:
{
This program demonstrates a TDesktopCanvas.
I wrote this to prepare my self for using Trinitron monitors :)
The code parts are gathered from different parts of the www.
}
program TrinitronTraining;
uses
Messages, Windows, Graphics, Forms;
type
TDesktopCanvas = class(TCanvas)
private
DC : hDC;
function GetWidth:Integer;
function GetHeight:Integer;
public
constructor Create;
destructor Destroy; override;
published
property Width: Integer read GetWidth;
property Height: Integer read GetHeight;
end;
{ TDesktopCanvas object }
function TDesktopCanvas.GetWidth:Integer;
begin
Result:=GetDeviceCaps(Handle,HORZRES);
end;
function TDesktopCanvas.GetHeight:Integer;
begin
Result:=GetDeviceCaps(Handle,VERTRES);
end;
constructor TDesktopCanvas.Create;
begin
inherited Create;
DC := GetDC(0);
Handle := DC;
end;
destructor TDesktopCanvas.Destroy;
begin
Handle := 0;
ReleaseDC(0, DC);
inherited Destroy;
end;
Const
YCount = 2;
Var
desktop : TDesktopCanvas;
dx,dy : Integer;
i : Integer;
F : Array[1..YCount] of TForm;
function CreateLine(Y : Integer) : TForm;
begin
Result := TForm.Create(Application);
with Result do begin
Left := 0;
Top := y;
Width := dx;
Height := 1;
BorderStyle := bsNone;
FormStyle := fsStayOnTop;
Visible := True;
end;
end;
procedure ProcessMessage;
var
Msg : TMsg;
begin
if PeekMessage(Msg, 0, 0, 0, PM_REMOVE) then
if Msg.Message = WM_QUIT then Application.Terminate;
end;
begin
desktop := TDesktopCanvas.Create;
try
dx := desktop.Width;
dy := desktop.Height div (YCount+1);
finally
desktop.free;
end;
for i:=1 to YCount do F[i]:=CreateLine(i*dy);
Application.NormalizeTopMosts;
ShowWindow(Application.Handle, SW_Hide);
for i:=1 to YCount do
SetWindowPos(F[i].Handle, HWND_TOPMOST, 0,0,0,0, SWP_NOACTIVATE+SWP_NOMOVE+SWP_NOSIZE);
{ use this if you don't want to stop
repeat
ProcessMessage;
until false;
{}
Sleep(15000);
for i:=1 to YCount do F[i].Free;
end.
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