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
"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 ?
- Forms and controls - see Roadmap Widgetset dependent components
- Creating TOpenGLControl with AGL context (see components/opengl/)
- Mouse events
- Keyboard events
What needs to be done next?
Item | Note | Dependencies | Responsible |
---|---|---|---|
Mouse Capture releasing | |||
TBrush Patterns | CGPatternCreate | ||
StretchMaskBlt | Implement: ROP, stretch mode | ||
TCalendar | no counterpart | ||
TFontDialog | FPShowHideFontPanel | ||
TListView | CreateDataBrowserControl | ||
TScrollBox, TCustomControl with scrollbars, TScrollingWinControl | HIScrollViewCreate | Tombo | |
IDE form designer | kOverlayWindowClass | ||
TClipboard | PasteboardCreate | ||
TPageSetupDialog | PMSessionPageSetupDialog | ||
TPrintDialog, TPrinterSetupDialog | PMSessionPrintDialog |
Bugs
Item | Note | Dependencies | Responsible |
---|---|---|---|
TCustomControl - keyboard focus | |||
TCustomEdit.CharCase | Is ignored when typing text | ||
TMemo.WordWrap | persistent bug, when word wrap is disabled the memo doesn't scroll to caret | ||
TMaskEdit | Every typed char is doubled |
Compatibility issues
Keyboard
- Apple Command key is mapped to ssCtrl per Apple Guidelines
- Apple control key is mapped to ssMeta
- Apple option key is mapped to its inscription, i.e. ssAlt
- Virtual key codes mapping (depends on keyboard language layout!)
- Shortcuts indication (ampersand)
Drawing on canvas outside OnPaint event
- won't be implemented
Drawing on screen device context
- won't be implemented
TControl.Color
- background of Carbon controls is transparent
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.