Solved

MDI form scrollbars

Posted on 1997-03-16
2
675 Views
Last Modified: 2012-05-04
 I want to make MDI main form scrollbars to be invisible
even in that case when one or more child windows come out
from the main form border.
  But setting up to .FALSE. of main form properties HorzScrollBar.Visible and VertyScrollBar.Visible give'nt effect. Then I try to redefine Style of the main form Style:=Style and not WS_HSROLL (WS_VSCROLL) by overriding the TForm.CreateParams metod, but with the same result.
  The only exit from this situation I find is to rewrite
TForm.AlignControls directly in forms.pas. (I made the scrollbars positions out from form border and then they are invisible though present physicaly.
  Unfortunately after this I have'nt a possibility to rebuild VCL and to use some modules (such as VBX tc.) because not all modules that are referencing to forms are present in source code.
   This Is my problem and I'd like to know, is there any way
to disable at all these scrollbars without coming into VCL
source code?
  Any help will be grateful.
0
Comment
Question by:riaukamo
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 1

Accepted Solution

by:
ozzy earned 100 total points
ID: 1334769
Line 2389 in Forms.pas:
            WS_CLIPCHILDREN or WS_HSCROLL or WS_VSCROLL or

Here's the problem... Commenting out the scroll styles will make things work as you wanted, but then, you got the version problem when installing other components....


Here's a unit fixing it.

Have your mainform call InstallHook(Self) sometime AFTER OnShow but before OnShow of any MDI CHild. I called it in the procedure creating a new MDI child.

Remember to call RemoveHook when the app terminates.

What happens is:
Everytime a MDI child is moved out of the MDI parent's window, a undocumented?? message, value $3F, is sent to the MDICLIENT window. The defaulthandler for this message obviously resets the window style to the one specified when creating the window. Unfortunately, I could not hook this message, therefore I just located an appropriate message to hook, and set the styles I want in the hook proc.




----------------------
unit ScrollFix;

interface
uses
  Forms, Messages, Windows;

function InstallHook (AForm : TForm) : BOOLEAN;
function RemoveHook : BOOLEAN;

implementation


// These styles will be removed from the window
const
  StylesToRemove = WS_VSCROLL or WS_HSCROLL;


// Globals, for faster access
var
  StyleFixupWindow,
  StyleFixupHook : INTEGER;


// The hook procedure
function StyleFixup (nCode : INTEGER; wParam : WORD; lParam : INTEGER) : INTEGER; stdcall;
var
  pcwr  : PCWPRetStruct;
begin
  pcwr := POINTER(lParam);

// WM_WINDOWPOSCHANGING seems to work. Tried a lot, but as far
// as I find, this one's stable.
  if (pcwr^.hwnd = StyleFixupWindow)
  and (pcwr^.message = WM_WINDOWPOSCHANGING) then begin

// Modify the window style.
    SetWindowLong
      (
        StyleFixupWindow,
        GWL_STYLE,
        GetWindowLong (StyleFixupWindow, GWL_STYLE) and not StylesToRemove
      );
  end;
  if nCode=HC_ACTION then Result := 0 else Result := CallNextHookEx(StyleFixupHook, nCode, wParam, lParam);
end;

function InstallHook (AForm : TForm) : BOOLEAN;
begin
// Installs the hook if not already installed.
  Result := StyleFixupWindow=0;
  if not Result then exit;
  StyleFixupHook := SetWindowsHookEx(WH_CALLWNDPROCRET, @StyleFixup, hInstance, 0);
  Result := StyleFixupHook<>0;
  if Result then StyleFixupWindow := AForm.CLientHandle;
end;

function RemoveHook : BOOLEAN;
begin
// Removes the hook if installed
  Result := StyleFixupWindow<>0;
  if Result then Result := UnhookWindowsHookEx (StyleFixupHook);
  if Result then StyleFixupWindow := 0;
  Application.ProcessMessages;
end;

initialization
// Better keep this, the compiler is a bit buggy and doesn't always
// initialize globals.
  StyleFixupWindow := 0;
end.
----------------------

0
 

Author Comment

by:riaukamo
ID: 1334770
Please answer if it's possible what I need to make your unit
to work under Delphi 1.0?
0

Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

A lot of questions regard threads in Delphi.   One of the more specific questions is how to show progress of the thread.   Updating a progressbar from inside a thread is a mistake. A solution to this would be to send a synchronized message to the…
Introduction The parallel port is a very commonly known port, it was widely used to connect a printer to the PC, if you look at the back of your computer, for those who don't have newer computers, there will be a port with 25 pins and a small print…
Nobody understands Phishing better than an anti-spam company. That’s why we are providing Phishing Awareness Training to our customers. According to a report by Verizon, only 3% of targeted users report malicious emails to management. With compan…

738 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question