Scott Duensing ae2aef0119 Add remote forms system: DFM converter, server library, and client engine

Text-based protocol for serving Delphi-designed forms over serial.
dfm2form converts binary DFM (TPF0) to protocol commands on Linux.
formsrv loads .form files and sends/receives via pluggable transport.
formcli creates native Win 3.1 controls and routes events back to server.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

2026-03-04 18:35:54 -06:00

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Remote Forms Protocol

Overview

Text-based protocol for remote GUI. A C server on Linux sends form/control commands over a transport layer; a Delphi 1.0 client on Windows 3.1 creates native controls and sends user events back.

Message Format

One command per message.
Transport delivers whole messages (today: newline-delimited over serial).
Strings are double-quoted with escapes: \" \\ \n \r \t.
Bare tokens (IDs, numbers, type names) are whitespace-delimited.
IDs are positive integers assigned by the server.

Server → Client Commands

FORM.CREATE

FORM.CREATE <formId> <width> <height> "<title>"

Create a new form with the given dimensions and title. The form is not shown until FORM.SHOW is sent.

FORM.SHOW

FORM.SHOW <formId>

FORM.HIDE

FORM.HIDE <formId>

FORM.DESTROY

FORM.DESTROY <formId>

Free the form and all its controls.

CTRL.CREATE

CTRL.CREATE <formId> <ctrlId> <type> <left> <top> <width> <height> [Key="val" ...]

Create a control on the specified form. Inline key/value properties are applied immediately after creation. See Control Types and Properties below.

CTRL.SET

CTRL.SET <formId> <ctrlId> Key="val" [Key="val" ...]

Update one or more properties on an existing control.

EVENT.BIND

EVENT.BIND <formId> <ctrlId> <eventName>

Wire an opt-in event handler. Auto-wired events do not need explicit binding.

EVENT.UNBIND

EVENT.UNBIND <formId> <ctrlId> <eventName>

Remove an event handler.

Client → Server Events

EVENT <formId> <ctrlId> <eventName> [<data>]

Event data varies by event type:

Event	Data
Click	(none)
DblClick	(none)
Change	`"new text"`
Select	`<index> "selected text"`
KeyDown	`<vkCode>`
KeyUp	`<vkCode>`
MouseDown	`<x> <y> <button>`
MouseUp	`<x> <y> <button>`
MouseMove	`<x> <y> <button>`
Enter	(none)
Exit	(none)
Close	(none)

Control Types

Type	Delphi Class	Auto-wired Events
Label	TLabel	(none)
Edit	TEdit	Change
Button	TButton	Click
CheckBox	TCheckBox	Click
ListBox	TListBox	Select
ComboBox	TComboBox	Select, Change
Memo	TMemo	Change

Opt-in events (require EVENT.BIND): DblClick, KeyDown, KeyUp, Enter, Exit, MouseDown, MouseUp, MouseMove.

Properties

Property	Applies To	Value Format
Caption	Label, Button, CheckBox	Quoted string
Text	Edit, ComboBox, Memo	Quoted string (`\n` for line breaks)
Items	ListBox, ComboBox	Quoted string (`\n`-delimited)
Checked	CheckBox	0 or 1
Enabled	All	0 or 1
Visible	All	0 or 1
MaxLength	Edit	Integer
ReadOnly	Edit, Memo	0 or 1
ScrollBars	Memo	0-3 (ssNone..ssBoth)
ItemIndex	ListBox, ComboBox	Integer (-1 = none)
TabOrder	All windowed controls	Integer

String Encoding

Strings in the protocol are always double-quoted.
Escape sequences: \" (literal quote), \\ (literal backslash), \n (newline), \r (carriage return), \t (tab).
Multi-line values (Memo text, ListBox items) use \n within a single quoted string.

Transport Layer

The protocol is transport-agnostic. Messages are delivered via:

int  ReadMessage(char *buf, int maxLen);   // returns bytes read, 0 = none
void WriteMessage(const char *buf);        // sends complete message

Current transport: newline-delimited serial (messages terminated by CR+LF). The transport handles framing; protocol layer never sees delimiters.

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