DelphiColorPreview

A lightweight RAD Studio (Delphi 12 Athens or newer) IDE plugin that shows a color swatch in the editor gutter next to every color literal in your source — like the color decorators in VS Code — and lets you Shift+click a swatch to pick a new color, rewriting the literal directly in your code. It understands both VCL (TColor) and FMX (TAlphaColor, with an alpha channel) color forms.

Features

• Color swatches in the left gutter, on every line that contains a color literal.

• Recognizes VCL and FMX color forms:

  Form	Example	Notes
  clXXX	clRed, clBtnFace	VCL named constants; system colors resolved to their real RGB
  RGB(r,g,b)	RGB(255, 128, 0)	integer-literal arguments only
  $00BBGGRR hex	$00FF8040	8-digit $00… → VCL TColor (BGR); auto-detected
  $AARRGGBB hex	$FF3366CC, $80FF0000	8-digit with a non-zero high byte → FMX TAlphaColor (ARGB); auto-detected
  $RRGGBB hex	$C0FFEE	6-digit → BGR or RGB per the byte-order mode (see below)
  claXXX	claRed, claDodgerblue	FMX TAlphaColor named constants
  TAlphaColorRec.X	TAlphaColorRec.Blue	FMX TAlphaColor record members
  TAlphaColors.X	TAlphaColors.Green	FMX TAlphaColor record members

• Byte order is mostly automatic. Only bare hex is ambiguous ($RRGGBB is BGR in VCL, RGB in FMX/web), and the plugin resolves it for you:

  • 8-digit hex is decided by its high byte — $00BBGGRR is a VCL TColor, while a non-zero high byte ($FF3366CC, $80FF0000) is an FMX TAlphaColor (ARGB, with alpha). No setting needed.
  • 6-digit hex has no such tell, so it follows the byte-order mode: Auto (the default — RGB in FMX units, BGR otherwise, detected from the unit's uses), BGR, or RGB. Set it in the picker; the choice is persisted. Named constants and RGB() always have a fixed order. Existing VCL projects are unaffected.

• Alpha aware. Translucent colors render as the color blended over a checkerboard so you can see the transparency; alpha is preserved (and editable) when you edit.

• Themed picker. The color editor matches the IDE's current theme (light/dark).

• Edit colors straight from the gutter (see Usage).

• One persisted setting (the byte-order mode); no toolbar, no menu — build, install, done.

Requirements

• RAD Studio 12 Athens or newer (Delphi 12+). It relies on the modern ToolsAPI.Editor code-editor notifier framework (TNTACodeEditorNotifier, INTACodeEditorState, gutter paint stages), which was introduced in 12 — the older INTAEditViewModifier painting API was deprecated as of 11.3. It is therefore not compatible with Delphi 11 or earlier.
• Win32 design-time package (the IDE host is a 32-bit process).

Delphi 13+: the source is forward-compatible (it uses only the stable base interfaces, which RAD Studio extends additively). Just recompile — a design package BPL is locked to its IDE version, so the D12 BPL won't load in D13. Open DelphiColorPreview.dproj in the newer IDE (it upgrades the project automatically) and rebuild.

Installation

1. Open DelphiColorPreview.dproj in RAD Studio 12.
2. Build the project.
3. Right-click the project in the Project Manager → Install.

That's it — the swatches show up in the editor gutter immediately. To uninstall, right-click the project → Uninstall (or remove it from Component → Install Packages…).

Prefer the command line? Run build.bat (it calls rsvars.bat + msbuild, Win32 / Debug) and then do step 3 in the IDE.

Usage

• A color swatch appears in the gutter next to every line that has a color literal — with or without a breakpoint on that line.

• Shift+click a swatch to open the picker:

  

  It has:

  • a preview (checkerboard behind translucent colors),
  • a Choose color… button that opens the native color dialog for the RGB hue,
  • an Alpha slider (enabled for TAlphaColor literals),
  • a Byte order (hex) selector — Auto / BGR / RGB, remembered across IDE restarts (only affects 6-digit hex; see Features).

• The picker matches the current IDE theme (light/dark).

• Confirming rewrites the literal in your code, keeping its original form:

  • hex stays hex — $00BBGGRR (VCL), $AARRGGBB (FMX alpha), or $RRGGBB per the mode,
  • RGB(r, g, b) stays an RGB() call,
  • clXXX / claXXX / TAlphaColorRec.X / TAlphaColors.X stay the matching named constant when one exists (otherwise a hex literal).

• The edit goes through the editor buffer, so Ctrl+Z undoes it like any other change.

• A plain (non-Shift) click is left untouched, so the gutter still works for breakpoints.

How it works

The package registers a single global INTACodeEditorEvents notifier through (BorlandIDEServices as INTACodeEditorServices).AddEditorEventsNotifier.

• Swatches are painted at the pgsEndPaint gutter stage, which runs once after the whole gutter is drawn with a clip covering the entire gutter. The plugin enumerates the visible lines (EditorState.TopLine..BottomLine → LineState[]) and draws a swatch in each line's GutterRect. Using the line's own gutter rectangle means there is no column-to-pixel math, so the swatch never drifts.
• Line text and geometry come straight from INTACodeEditorLineState (.Text, .GutterRect).
• Editing goes through IOTAEditView.Buffer.EditPosition (Move / Delete / InsertText) so the IDE records a normal, undoable edit.
• The Auto byte-order mode detects an FMX unit by scanning the top of the active buffer (IOTAEditBuffer.CreateReader) for an FMX. unit reference, cached per file.
• The picker registers itself with IOTAIDEThemingServices and calls ApplyTheme, so it follows the IDE's light/dark theme.

Source layout

File	Responsibility
ColorPreview.Parser.pas	FindColorTokens — scans one line into color tokens; FormatColorLiteral — formats a token back to source
ColorPreview.Render.pas	DrawColorPreview — solid / checkerboard-blended swatch drawing (shared)
ColorPreview.Settings.pas	the persisted byte-order mode (Auto/BGR/RGB) in the IDE registry
ColorPreview.PickerForm.pas	the themed custom picker (preview, alpha slider, byte-order selector)
ColorPreview.Notifier.pas	TColorPreviewNotifier — paints swatches, detects FMX units, handles the click
ColorPreview.Register.pas	registers / unregisters the notifier on package load
DelphiColorPreview.dpk	the design-only package (requires rtl, vcl, designide)

License

MIT