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Free Vision Modern (fv-delphi-modern)

A modernized port of the Free Vision (FV) text-mode UI framework from Free Pascal to modern Delphi (12+).

Free Vision is a classic console-based GUI toolkit originally derived from Borland's Turbo Vision. This modern variant uses Delphi CLASS syntax instead of the legacy Turbo Pascal OBJECT syntax, providing better IDE integration, proper inheritance, and modern memory management.

Features

  • Complete TUI Framework: Windows, dialogs, menus, status bars, buttons, input fields, and more
  • Modern Architecture: Interfaces (IFVDrawable, ISerializable), RTL generics (TObjectList<T>, TStringList)
  • Full Unicode Support: Double-width characters, emoji, and CJK glyphs rendered correctly throughout the framework via TDrawCell-based drawing system
  • Text Editor: Full-featured editor with find/replace, clipboard, undo, and file operations
  • Hex Editor: Binary file viewer/editor with hex and ASCII modes
  • String Grid: Spreadsheet-like grid with sorting, editing, selection, and CSV import/export
  • Standard Dialogs: Message boxes, file open/save dialogs, color selection, ASCII table
  • Advanced Controls: Tab controls, outline/tree views, progress gauges, timed dialogs
  • Layout Components: Splitter panels with draggable divider, accordion with collapsible sections
  • Extended Widgets: Toolbar, breadcrumb navigation, combo box dropdown, progress bar, editor gutter with pluggable providers, toast notifications
  • SIXEL Graphics: Adaptive 256-color SIXEL encoder, direct SIXEL canvas drawing, and BMP/SIXEL image viewer
  • Input Validation: Built-in validators for ranges, patterns, and lookups
  • JSON Serialization: Views implement ISerializable for state persistence
  • Windows Console: Native Windows Console API for display and input
  • Terminal Emulator: Pseudo-terminal windows using Windows ConPTY

SIXEL Graphics

SIXEL support is optimized for Windows Terminal sessions and integrates with the normal Free Vision view system.

What is supported

  • TSixelEncoder (src/SixelEncoder.pas): converts TPixelGrid data ($00RRGGBB) to SIXEL DCS strings using adaptive palette quantization (up to 256 registers)
  • TSixelView (src/SixelView.pas): renders pre-encoded SIXEL data from memory or .sixel/.six/.sxl files
  • TSixelCanvasView (src/SixelView.pas): direct pixel drawing API for generated/animated graphics (SetPixel, FillRect, DrawLine, Clear)
  • TImageWindow/TImageView (src/ImageView.pas): loads both BMP and SIXEL files, supports scrolling and safe viewport cropping before SIXEL encoding

True color vs SIXEL palette

Windows Terminal supports true-color text attributes, but SIXEL itself remains palette-based.
Practical limit is still 256 color registers per emitted SIXEL image, so quality depends on quantization and dithering choices.

Dithering control

TSixelEncoder supports error-diffusion dithering to reduce visible color banding:

  • Auto-enabled for coarser quantization steps
  • Force on: FV_SIXEL_DITHER=1 (also accepts on, true)
  • Force off: FV_SIXEL_DITHER=0 (also accepts off, false)

Cell-size override

If terminal pixel cell detection is wrong, you can override with:

  • FV_CELL_W=<pixels>
  • FV_CELL_H=<pixels>

FVTest demos

Test -> New Components contains:

  • Image Viewer (BMP + SIXEL files)
  • SIXEL Spectrometer (direct animated bar rendering on TSixelCanvasView)
  • SIXEL Animated Sine (direct animated waveform drawing on TSixelCanvasView)

Clipboard Integration

System clipboard support is provided by src/FVClipboard.pas and is shared across editor-style controls.

API

Function Description
ClipboardSetText(const Text: string): Boolean Writes Unicode text to Windows clipboard
ClipboardGetText: string Reads text from Windows clipboard
ClipboardHasText: Boolean Returns whether text data is available

Common key usage in FVTest demos

  • Ctrl+Ins: copy selection
  • Shift+Ins: paste clipboard text

The Test menu includes clipboard-focused examples:

  • Test -> Editor -> Clipboard
  • Test -> New Components -> Clipboard

Terminal Emulator

The terminal component (TTerminalWindow) provides a VT100-compatible terminal emulator using Windows ConPTY. It supports running command-line applications including other Free Vision apps.

Keyboard Controls

The terminal uses Ctrl+A as the escape prefix (like GNU screen):

Key Sequence Action
Ctrl+A, then any key Exit capture mode, send key to outer app
Ctrl+A, Ctrl+A Send literal Ctrl+A to child process
Ctrl+A, M Toggle terminal mouse mode (passthrough/select)
Ctrl+C / Ctrl+Ins Copy terminal selection to clipboard
Ctrl+V / Shift+Ins Paste clipboard text to terminal process
Right click Copy selection, or paste when no selection
Shift+PageUp/Down Scroll through scrollback buffer
Mouse wheel Scroll through scrollback buffer

Re-entering Capture Mode

After exiting capture mode with Ctrl+A:

  • Click on the terminal to re-enter capture mode
  • Press Enter or Esc to re-enter capture mode

The terminal window title shows the current mouse mode:

  • Mouse:Pass forwards mouse to child apps that enable VT mouse reporting
  • Mouse:Select keeps mouse local for text selection/scrolling
  • Mouse:Select keeps keyboard capture, so typing continues while mouse stays local
  • New terminal windows start in Mouse:Select; use Ctrl+A, M to switch to passthrough
  • Entering alternate screen (?1049/?1047/?47) auto-switches to Mouse:Pass, then restores previous mode on exit

Features

  • VT100/ANSI escape sequence support
  • Scrollback buffer with configurable size
  • Text selection with mouse (double-click for word selection)
  • Copy/paste support (Ctrl+C/Ctrl+Ins copy selection, Ctrl+V/Shift+Ins paste)
  • Visual bell
  • Window title from OSC sequences
  • Session logging
  • Text reflow on resize

String Grid

The TStringGrid component (Grid.pas) provides a spreadsheet-like data grid for console applications.

Features

  • Sortable columns with visual indicators
  • Cell editing (F2 or direct typing)
  • Row and cell selection modes
  • Clipboard support (copy/paste)
  • Undo support
  • Column resizing and auto-fit
  • Fixed header rows
  • JSON serialization for layout

CSV Import/Export

The grid supports RFC 4180-compliant CSV files:

// Load CSV file
Grid.LoadFromCSV('data.csv');

// Save to CSV
Grid.SaveToCSV('output.csv');

// With options
var Opts := TCSVOptions.Create;
Opts.Delimiter := cdSemicolon;        // or cdComma, cdTab, cdPipe, cdAuto
Opts.CustomDelimiter := '~';          // Override with any character
Opts.UseFixedHeaderRow := True;       // Headers as fixed row 0
Opts.Encoding := ceUTF8BOM;           // UTF-8 with BOM (Excel compatible)
Grid.LoadFromCSV('data.csv', Opts);
Opts.Free;

TCSVOptions Properties

Property Default Description
Delimiter cdComma Field delimiter (comma, semicolon, tab, pipe, auto-detect)
CustomDelimiter #0 Override delimiter with any character
Encoding ceUTF8BOM File encoding (UTF-8 BOM, UTF-8, ANSI)
HasHeaders True First row contains column headers
UseFixedHeaderRow False Put headers in fixed row 0
TrimWhitespace False Trim spaces from values
AutoCreateColumns True Create columns from CSV structure

Hex Editor

The THexEditor component (HexEdit.pas) provides a binary file viewer and editor.

Features

  • Classic hex editor layout (address | hex bytes | ASCII)
  • Dual editing modes: hex nibbles or ASCII characters
  • Selection support with keyboard (Shift+arrows) and mouse
  • Modified byte highlighting
  • File load/save operations
  • Pluggable data source interface (IHexDataSource)

Keyboard Controls

Key Action
Arrow keys Navigate bytes
Tab Toggle between hex and ASCII mode
Shift+Arrows Extend selection
0-9, A-F Edit hex nibble (in hex mode)
Any printable Edit ASCII character (in ASCII mode)
Home/End Jump to start/end of row
Ctrl+Home/End Jump to start/end of file
Page Up/Down Scroll by page

Usage

var
  HexEdit: THexEditor;
  Source: TMemoryHexSource;
begin
  Source := TMemoryHexSource.Create;
  Source.LoadFromFile('data.bin');

  HexEdit := THexEditor.Create(Bounds, Source);
  // ... add to window

  // Save changes
  Source.SaveToFile('data.bin');
end;

Unicode and Emoji Support

The framework uses a TDrawCell-based drawing system where each screen cell stores a full string instead of a single Char. This allows proper rendering of:

  • Emoji: Characters like CheckMark, CrossMark, Diamond rendered as true Unicode glyphs
  • CJK characters: Double-width East Asian characters occupy two screen cells
  • Surrogate pairs: Code points above U+FFFF (e.g. emoji) handled via Delphi's UTF-16 surrogate pair encoding
  • Box-drawing characters: Full set of Unicode box-drawing and block elements (FVBoxChars.pas)

The rendering pipeline (TDrawBuffer -> WriteBuf -> UnicodeCharBuf -> VT escape sequences) preserves full Unicode fidelity from view drawing through to terminal output.

Requirements

  • Delphi 12.x or later
  • Windows 32-bit or 64-bit target

Getting Started

  1. Open FVTest.dproj in the Delphi IDE
  2. Build and run the project
  3. Explore the Test menu to see various components in action

Minimal Application

program MyApp;

uses
  App, Views, Menus, Drivers;

type
  TMyApp = class(TApplication)
    procedure InitMenuBar; override;
    procedure InitStatusLine; override;
  end;

procedure TMyApp.InitMenuBar;
var
  R: TRect;
begin
  GetExtent(R);
  R.B.Y := R.A.Y + 1;
  MenuBar := TMenuBar.Create(R, NewMenu(
    NewSubMenu('~F~ile', hcNoContext, NewMenu(
      NewItem('E~x~it', 'Alt-X', kbAltX, cmQuit, hcNoContext, nil)),
    nil)));
end;

procedure TMyApp.InitStatusLine;
var
  R: TRect;
begin
  GetExtent(R);
  R.A.Y := R.B.Y - 1;
  StatusLine := TStatusLine.Create(R,
    NewStatusDef(0, $FFFF,
      NewStatusKey('~Alt-X~ Exit', kbAltX, cmQuit, nil),
    nil));
end;

var
  App: TMyApp;
begin
  App := TMyApp.Create;
  App.Run;
  App.Free;
end.

Project Structure

src/
  FVCommon.pas      - Platform types (Sw_Word, PString, etc.)
  FVInterfaces.pas  - Interface definitions (IFVDrawable, ISerializable, etc.)
  FVSerialization.pas - JSON serialization helpers
  FVClipboard.pas   - Windows clipboard integration helpers
  Objects.pas       - Stream classes, string utilities
  Video.pas         - Console output (Windows Console API)
  Drivers.pas       - Keyboard and mouse input handling
  Views.pas         - View hierarchy (TView, TGroup, TWindow, etc.)
  Menus.pas         - Menu system (TMenuBar, TMenuBox, TStatusLine)
  App.pas           - Application framework (TApplication)
  Dialogs.pas       - Dialog controls (TDialog, TButton, TInputLine, etc.)
  Grid.pas          - TStringGrid with CSV import/export
  HexEdit.pas       - THexEditor binary viewer/editor
  SixelEncoder.pas  - Adaptive SIXEL encoder (palette + dithering)
  SixelView.pas     - TSixelView + TSixelCanvasView for SIXEL rendering
  ImageView.pas     - BMP/SIXEL viewer window and scrollable image view
  Validate.pas      - Input validation
  MsgBox.pas        - Message box helpers
  StdDlg.pas        - Standard file dialogs
  Editors.pas       - Text editor components
  ColorSel.pas      - Color selection dialog
  Outline.pas       - Tree/outline view
  Tabs.pas          - Tab control
  Statuses.pas      - Progress gauges
  Gadgets.pas       - Clock and heap views
  ProgressBar.pas   - Progress bar indicator
  Breadcrumb.pas    - Clickable path navigation
  ToolBar.pas       - Horizontal button bar
  ComboBox.pas      - Dropdown select control
  Splitter.pas      - Draggable panel divider + split group container
  Accordion.pas     - Collapsible section stack
  EditorGutter.pas  - Multi-column editor gutter (line numbers, bookmarks, breakpoints, diff)
  Notification.pas  - Auto-dismissing toast popups

See ARCHITECTURE.md for detailed class hierarchies and diagrams.

Porting Notes

  • Uses modern Delphi CLASS syntax with proper inheritance and override
  • All view classes derive directly from TObject (no intermediate base class)
  • Views implement interfaces: IFVDrawable, IFVEventHandler, IFVDataAware, ISerializable
  • Uses RTL generics: TObjectList<T>, TStringList (no custom collection classes)
  • TClass.Create / Object.Free instead of New(P, Init) / Dispose(P, Done)
  • Pointer types aliased for compatibility: PView = TView
  • ShortString used for FV string types (Sw_String, PString)
  • Windows Console API for video output and input
  • Range checking should be OFF at project level

Known Limitations

  • New edge-cases, oversights or errors may be introduced in this project

Known Issues

  • Corruption in ASCII Table display
  • Corruption in TStringGrid with wide Unicode characters

License

This library is distributed under the GNU Lesser General Public License (LGPL) with the following linking exception:

As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.

See COPYING.TXT for the complete license text.

Credits

  • Original Turbo Vision by Borland International
  • Free Vision by the Free Pascal Development Team
  • Delphi port by Claude Code (Anthropic)

Contributing

Bug reports and contributions are welcome. Please ensure any modifications maintain compatibility with the original Free Vision API where possible.

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Modernized Free Vision for Delphi

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