Carbon interface internals

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This article applies to macOS only.

See also: Multiplatform Programming Guide

This article applies to iOS only.

See also: Multiplatform Programming Guide

This page gives an overview of the LCL Carbon interface for Mac OS X and will help new developers.

For installation and creating a first Carbon application refer to Carbon Interface.

Documentation about Carbon

• Apple Carbon docs

• Apple Mailing List search

• Carbon Book for download

• Carbon Dev

• "Learning Carbon" sample book chapter

• Free Pascal's Carbon API unit is FPCMacOSAll.pas in /usr/local/share/fpcsrc/packages/extra/univint.

Carbon interface development basics

• Target Mac OS X version is 10.4
• Avoid using obsolete or deprecated APIs and functions (e. g. QuickDraw vs. Quartz 2D)
• Use object approach
• Check Carbon calls result with OSError function
• Assume UTF-8 encoded strings between LCL and Carbon widgetset (for future Lazarus Unicode support)

What is already working ?

• Features - see Roadmap#Status_of_features_on_each_widgetset
• Forms and controls - see Roadmap#Status_of_components_on_each_widgetset
• Creating TOpenGLControl with AGL context (see components/opengl/)
• Mouse events
• Keyboard events

What needs to be done next?

See Bug Tracker Carbon open issues

Carbon IDE Bugs

Item	Note	Dependencies	Responsible
'...' buttons in dialogs	Now they are too large I think
OK/Cancel	Many dialogs have non-Mac check-X glyphs
Menu bar	Too wide for 1024x768 display resolution
Lazarus menu	Help About and app prefs (Environment options) should be accessible here
Menus	Many missing or non-standard menu shortcuts: File New should be Cmd+N File Save As should be Shift+Cmd+S File Quit should be Cmd+Q Search Find should be Cmd+F Search Find Next should be Cmd+G Search Find Previous should be Shift+Cmd+G (Goto line and Procedure List need to be reassigned) Option+Cmd+F does not bring up Search Results F11 behaves weird!

See Bug Tracker Carbon IDE open issues

Compatibility issues

Go to Carbon_interface_issues.

How to add a new control

For example TButton.

TButton is defined in lcl/buttons.pp. This is the platform independent part of the LCL, which is used by the normal LCL programmer.

Its widgetset class is in lcl/widgetset/wsbuttons.pp. This is the platform independent base for all widgetsets (carbon, gtk, win32, ...).

Its Carbon interface class is in lcl/interfaces/carbon/carbonwsbuttons.pp:

 TCarbonWSButton = class(TWSButton)
 private
 protected
 public
   class function  CreateHandle(const AWinControl: TWinControl; const AParams: TCreateParams): TLCLIntfHandle; override;
 end;

Every WS class that actually implements something must be registered. See the initialization section at the end of the carbonwsXXX.pp unit:

 RegisterWSComponent(TCustomButton, TCarbonWSButton);

TCarbonWSButton overrides CreateHandle to create a Carbon button helper class called TCarbonButton in carbonprivate.pp, which really creates the button control in the Carbon and installs event handlers.