How to do that when I'm in the main window of my system by pressing F1 will display the help muetre in pdf format. how do I intercept was pressed the F1 key on my main window?
I use Delphi XE2
Thanks for the help!
Use the Application.OnHelpCommand event, which you can either assign in code:
interface
type
TForm1 = class(TForm)
// IDE generated code
private
procedure AppOnHelp(Command: Word; Data: Integer;
var CallHelp: Boolean);
end;
implementation
procedure TForm1.FormCreate(Sender: TObject);
begin
Application.OnHelp := AppOnHelp;
end;
Or assign by using a TApplicationEvents component and creating a handler for the OnHelp event in the Object Inspector's Events tab.
You can set CallHelp to false to prevent the normal help processing, and launch your own help file via ShellExecute.
procedure TForm1.AppOnHelp(Command: Word; Data: Integer;
var CallHelp: Boolean);
begin
CallHelp := False;
// Launch your own help here
end;
Related
I want my form to handle the arrow keys, and I can do it -- as long as there is no button on the form. Why is this?
Key messages are processed by the controls themselves who receives these messages, that's why when you're on a button the form is not receiving the message. So normally you would have to subclass these controls, but the VCL is kind enough to ask the parenting form what to do if the form is interested:
type
TForm1 = class(TForm)
..
private
procedure DialogKey(var Msg: TWMKey); message CM_DIALOGKEY;
..
procedure TForm1.DialogKey(var Msg: TWMKey);
begin
if not (Msg.CharCode in [VK_DOWN, VK_UP, VK_RIGHT, VK_LEFT]) then
inherited;
end;
François editing: to answer the OP original question, you need to call onKeyDown somehow so that his event code would work (feel free to edit; was too long for a comment).
type
TForm1 = class(TForm)
Button1: TButton;
Button2: TButton;
Button3: TButton;
Button4: TButton;
procedure FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
private
{ Private declarations }
procedure DialogKey(var Msg: TWMKey); message CM_DIALOGKEY;
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.DialogKey(var Msg: TWMKey);
begin
case Msg.CharCode of
VK_DOWN, VK_UP, VK_RIGHT, VK_LEFT:
if Assigned(onKeyDown) then
onKeyDown(Self, Msg.CharCode, KeyDataToShiftState(Msg.KeyData));
else
inherited
end;
end;
procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
begin
case Key of
VK_DOWN: Top := Top + 5;
VK_UP: Top := Top - 5;
VK_LEFT: Left := Left - 5;
VK_RIGHT: Left := Left + 5;
end;
end;
Arrow keys are used to navigate between buttons on a form. This is standard Windows behaviour. Although you can disable this standard behaviour you should think twice before going against the platform standard. Arrow keys are meant for navigation.
If you want to get the full low down on how a key press finds its way through the message loop I recommend reading A Key's Odyssey. If you want to intercept the key press before it becomes a navigation key, you need to do so in IsKeyMsg or earlier. For example, Sertac's answer gives one such possibility.
Only the object that has the focus can receive a keyboard event.
To let the form have access to the arrow keys event,
declare a MsgHandler in the public part of the form.
In the form create constructor, assign the Application.OnMessage to this MsgHandler.
The code below intercepts the arrow keys only if they are coming from a TButton descendant. More controls can be added as needed.
procedure TForm1.FormCreate(Sender: TObject);
begin
Application.OnMessage := Self.MsgHandler;
end;
procedure TForm1.MsgHandler(var Msg: TMsg; var Handled: Boolean);
var
ActiveControl: TWinControl;
key : word;
begin
if (Msg.message = WM_KEYDOWN) then
begin
ActiveControl := Screen.ActiveControl;
// if the active control inherits from TButton, intercept the key.
// add other controls as fit your needs
if not ActiveControl.InheritsFrom(TButton)
then Exit;
key := Msg.wParam;
Handled := true;
case Key of // intercept the wanted keys
VK_DOWN : ; // doStuff
VK_UP : ; // doStuff
VK_LEFT : ; // doStuff
VK_RIGHT : ; // doStuff
else Handled := false;
end;
end;
end;
Because they are preempted to deal with setting the focus on the next available WinControl.
(I'm pretty sure that if you put an Edit instead of a Button you see the same thing).
If you want to handle them yourself, you can provide the Application with an OnMessage event that will filter those before they are processed and handle them yourself there.
var
KBHook: HHook; {this intercepts keyboard input}
implementation
{$R *.dfm}
function KeyboardHookProc(Code: Integer; WordParam: Word; LongParam: LongInt): LongInt; stdcall;
begin
case WordParam of
vk_Space: ShowMessage ('space') ;
vk_Right:ShowMessage ('rgt') ;
vk_Left:ShowMessage ('lft') ;
vk_Up: ShowMessage ('up') ;
vk_Down: ShowMessage ('down') ;
end; {case}
end;
procedure TForm4.FormCreate(Sender: TObject);
begin
KBHook:=SetWindowsHookEx(WH_KEYBOARD,#KeyboardHookProc,HInstance,GetCurrentThreadId());
end;
This code will work even when a control is focused (buttons , listboxes), so be careful some controls may loose their keyboard events (Read David haffernans answer) .
keyboard events with Focused controls
eg: If you are having textbox in your app and want to recive text(if focused) also , then
add an applicationevent1
procedure TForm4.ApplicationEvents1Message(var Msg: tagMSG;var Handled: Boolean);
begin
if Msg.message = WM_KEYFIRST then
KBHook:=SetWindowsHookEx(WH_KEYBOARD,#KeyboardHookProc,HInstance,GetCurrentThreadId());
end;
add the following code at the bottom of the function KeyboardHookProc
UnhookWindowsHookEx(KBHook);
and remove
KBHook:=SetWindowsHookEx(WH_KEYBOARD,#KeyboardHookProc, HInstance,
GetCurrentThreadId());
from oncreate event.
I need to write an application that displays two different pictures in two instances of the application. These pictures must look as if they were put side by side on the canvas of the same window but for internal reasons it must be two different applications not a single one. Is there any way to turn off the window frame regardless of what the user's Windows settings are? I still want to retain the title bar and the close/minimize/maximize buttons.
Bonus points if the two (or multiple) windows look and react like a single one to the user.
A Delphi example would be nice but I can probably do with a hint on which flags or whatever to set using Win32 API (no dotNET please).
Since windows with title bars always have borders, your next option is to make a borderless window and then paint a title bar at the top of the window yourself. That means handling mouse messages, too. Start with wm_NCHitTest. To make a borderless window, override your form's CreateParams method and set the Style field so there's no border.
This creates a Form without side or bottom borders:
type
TForm1 = class(TForm)
private
FBorderWidth: Integer;
FTitleHeight: Integer;
procedure AppRestored(Sender: TObject);
procedure WMNCCalcSize(var Message: TWMNCCalcSize); message WM_NCCALCSIZE;
procedure WMNCPaint(var Message: TWMNCPaint); message WM_NCPAINT;
protected
procedure Resize; override;
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
{ TForm1 }
procedure TForm1.AppRestored(Sender: TObject);
begin
Repaint;
end;
procedure TForm1.Resize;
begin
inherited Resize;
if FBorderWidth = 0 then
begin
FBorderWidth := (Width - ClientWidth) div 2;
FTitleHeight := Height - ClientHeight - FBorderWidth;
Application.OnRestore := AppRestored;
end;
Invalidate;
end;
procedure TForm1.WMNCCalcSize(var Message: TWMNCCalcSize);
begin
inherited;
with Message.CalcSize_Params^ do
begin
Dec(rgrc[0].Left, FBorderWidth);
Inc(rgrc[0].Right, FBorderWidth);
Inc(rgrc[0].Bottom, FBorderWidth);
end;
end;
procedure TForm1.WMNCPaint(var Message: TWMNCPaint);
begin
DeleteObject(Message.RGN);
Message.RGN := CreateRectRgn(Left, Top, Left + Width, Top + FTitleHeight);
inherited;
end;
I want to minimize a Delphi application to the systray instead of the task bar.
The necessary steps seem to be the following:
Create icon which should then be displayed in the systray.
When the user clicks the [-] to minimize the application, do the following:
Hide the form.
Add the icon (step #1) to the systray.
Hide/delete the application's entry in the task bar.
When the user double-clicks the application's icon in the systray, do the following:
Show the form.
Un-minimize the application again and bring it to the front.
If "WindowState" is "WS_Minimized" set to "WS_Normal".
Hide/delete the application's icon in the systray.
When the user terminates the application, do the following:
Hide/delete the application's icon in the systray.
That's it. Right?
How could one implement this in Delphi?
I've found the following code but I don't know why it works. It doesn't follow my steps described above ...
unit uMinimizeToTray;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ShellApi;
const WM_NOTIFYICON = WM_USER+333;
type
TMinimizeToTray = class(TForm)
procedure FormCreate(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
procedure CMClickIcon(var msg: TMessage); message WM_NOTIFYICON;
private
{ Private-Deklarationen }
public
{ Public-Deklarationen }
end;
var
MinimizeToTray: TMinimizeToTray;
implementation
{$R *.dfm}
procedure TMinimizeToTray.CMClickIcon(var msg: TMessage);
begin
if msg.lparam = WM_LBUTTONDBLCLK then Show;
end;
procedure TMinimizeToTray.FormCreate(Sender: TObject);
VAR tnid: TNotifyIconData;
HMainIcon: HICON;
begin
HMainIcon := LoadIcon(MainInstance, 'MAINICON');
Shell_NotifyIcon(NIM_DELETE, #tnid);
tnid.cbSize := sizeof(TNotifyIconData);
tnid.Wnd := handle;
tnid.uID := 123;
tnid.uFlags := NIF_MESSAGE or NIF_ICON or NIF_TIP;
tnid.uCallbackMessage := WM_NOTIFYICON;
tnid.hIcon := HMainIcon;
tnid.szTip := 'Tooltip';
Shell_NotifyIcon(NIM_ADD, #tnid);
end;
procedure TMinimizeToTray.FormClose(Sender: TObject; var Action: TCloseAction);
begin
Action := caNone;
Hide;
end;
end.
If it still works, it's probably easiest to use JVCL's TJvTrayIcon to handle it automatically.
I would recommend using CoolTrayIcon. The author has already worked out all the issues involved with tray icons. Its free with source and examples and very debugged.
http://subsimple.com/delphi.asp
Instead of Application.BringToFront; use SetforegroundWindow(Application.Handle);
In the following text I'll be referring to the step numbers mentioned in the question:
The following solution is without any additional components. It's very easy to implement.
Step #1:
Just use the application's main icon (see following code).
Step #2:
procedure TForm1.ApplicationEvents1Minimize(Sender: TObject);
begin
Shell_NotifyIcon(NIM_ADD, #TrayIconData);
Form1.Hide;
end;
Step #3:
procedure TForm1.TrayMessage(var Msg: TMessage);
begin
if Msg.lParam = WM_LBUTTONDOWN then begin
Form1.Show;
Form1.WindowState := wsNormal;
Application.BringToFront;
Shell_NotifyIcon(NIM_DELETE, #TrayIconData);
end;
end;
Step #4:
procedure TForm1.FormDestroy(Sender: TObject);
begin
Shell_NotifyIcon(NIM_DELETE, #TrayIconData);
end;
Necessary code in interface part:
uses
[...], ShellApi;
const
WM_ICONTRAY = WM_USER + 1;
type
TForm1 = class(TForm)
[...]
procedure TrayMessage(var Msg: TMessage); message WM_ICONTRAY;
end;
The only problem: The application can be minimized to the systray only once. The next time you want to minimize it, nothing will happen. Why?
Source: delphi.about.com
I would like to prevent copy, cut and paste in my TEdit. How can I do this?
I tried setting the Key=NULL on KeyDown event when CTRL+V was pressed on the control, but it didn't work.
You'll need to prevent the WM_CUT, WM_COPY, and WM_PASTE messages from being sent to your TEdit. This answer describes how do to this using just the Windows API. For the VCL, it may be sufficient to subclass TEdit and change its DefWndProc property or override its WndProc method.
Assign this to TEdit.OnKeyPress :
procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
if (Key=#22) or (Key=#3) then Key:=#0; // 22 = [Ctrl+V] / 3 = [Ctrl+C]
end;
I know this is an old question but I'll add what I have found. The original poster almost had the solution. It works fine if you ignore cut/copy/paste in the key press event instead of the key down event. ie (c++ builder)
void __fastcall Form::OnKeyPress(TObject *Sender, System::WideChar &Key)
{
if( Key==0x03/*ctrl-c*/ || Key==0x16/*ctrl-v*/ || Key==0x018/*ctrl-x*/ )
Key = 0; //ignore key press
}
You can use some global programs that grab shortcuts and block C-V C-C C-X when TEdit window is active
Uses Clipbrd;
procedure TForm1.Edit1Enter(Sender: TObject);
begin
Clipboard.AsText := '';
end;
An old question, but the same bad answers are still floating around.
unit LockEdit;
// Version of TEdit with a property CBLocked that prevents copying, pasting,
// and cutting when the property is set.
{$mode objfpc}{$H+}
interface
uses
Classes, SysUtils, StdCtrls, Windows;
type
TLockEdit = class(TEdit)
protected
procedure WndProc(var msg: TMessage); override;
private
FLocked: boolean;
public
property CBLocked: boolean read FLocked write FLocked default false;
end;
implementation
procedure TLockEdit.WndProc(Var msg: TMessage);
begin
if ((msg.msg = WM_PASTE) or (msg.msg = WM_COPY) or (msg.msg = WM_CUT))
and CBLocked
then msg.msg:=WM_NULL;
inherited;
end;
end.
I'm trying to control the coordinates of where my program opens a new window because currently they're opening ontop of each other. Does anyone have a working example of how to do this?
You can always set the .Top and .Left properties manually, like this:
procedure TForm1.Button1Click(Sender: TObject);
var
frm : TForm;
begin
frm := TForm.Create(Self);
frm.Left := 100; //replace with some integer variable
frm.Top := 100; //replace with some integer variable
frm.Show;
end;
However, Windows has a default window placement algorithm that tries to keep the title bars of each window visible. On my computer, repeated clicks to this Button1 procedure give nicely stacked windows:
procedure TForm1.Button1Click(Sender: TObject);
var
frm : TForm;
begin
frm := TForm.Create(Self);
frm.Show;
end;
Also, don't forget that you can use the built-in set of TPosition locations:
procedure TForm1.Button1Click(Sender: TObject);
var
frm : TForm;
begin
frm := TForm.Create(Self);
frm.Position := poOwnerFormCenter;
{
Other possible values:
TPosition = (poDesigned, poDefault, poDefaultPosOnly, poDefaultSizeOnly,
poScreenCenter, poDesktopCenter, poMainFormCenter, poOwnerFormCenter);
//}
frm.Show;
end;
This type of functionality has been explained for C# in another question on SO.
Also, for Delphi, check out Understanding and Using Windows Callback Functions in Delphi which describes getting handles for windows that are currently open. And see Shake a window (form) from Delphi code which describes how to move a window once you've got its handle.