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doc: Intuition bootcamp — comprehensive enrichment of all subsystem articles
Transformed 8 stub articles (720 lines total) into full bootcamp-grade references (5,100+ lines) with architecture diagrams, complete code examples, struct field references, pitfalls, and best practices. IDCMP (idcmp.md — 1,060 lines): - IntuiMessage field reference with types, sizes, value ranges - Use-case cookbook: double-click, rubber-band, multi-signal, BOOPSI - When to use IDCMP vs alternatives (decision flowchart) - 5 named antipatterns with WRONG/RIGHT code - Memory safety checklist and defensive event loop template - Cross-platform comparison table (Win32, X11, Cocoa, Qt) Input Events (input_events.md — 850 lines): - Event class routing and QoS analysis (priority-as-QoS hierarchy) - Intuition consumption table (what survives the handler chain) - lowlevel.library bypass for CD32/game input - Latency analysis with pipeline timing budget (68000 vs 68040) - Input strategy comparison (IDCMP vs handler vs direct hardware) - Game input patterns: direct HW polling, CIA keyboard, hybrid handler - Signal pattern for proper handler→application communication Windows (windows.md — 370 lines): - Window anatomy diagram, WA_ tag reference tables - Refresh modes comparison (Simple/Smart/SuperBitMap) - Window types: standard, backdrop, borderless, GimmeZeroZero - Coordinate system, border offsets, struct Window fields - Modification API (move, resize, title, busy pointer) Gadgets (gadgets.md — 403 lines): - Three-generation evolution (raw/GadTools/BOOPSI) - Complete GadTools lifecycle with setup, creation, events, cleanup - Runtime state updates (GadTools vs raw Intuition) - Raw struct Gadget: GFLG_*, GACT_*, GTYP_* flag tables - Proportional and string gadget internals BOOPSI (boopsi.md — 505 lines): - Class hierarchy Mermaid diagram - Method dispatch sequence diagram - ICA interconnection architecture (icclass, modelclass, ICTARGET_IDCMP) - Full custom gadget class tutorial (4 steps with complete code) - Built-in class reference table - C++/Qt analog comparison table Menus (menus.md — 378 lines): - Menu hierarchy diagram (Menu → Item → Sub-Item) - GadTools NewMenu workflow with field reference - Event handling with multi-select chain walking - Checkmark/mutual exclusion, sub-menus, dynamic modification - Keyboard shortcut system (single-char and NM_COMMANDSTRING) Requesters (requesters.md — 370 lines): - EasyRequest return value logic table - ASL file requester with multi-select and full tag reference - ASL font and screenmode requesters - Non-blocking BuildEasyRequest/SysReqHandler pattern - Requester state persistence IntuitionBase (intuition_base.md — 267 lines): - Library version table (OS 1.2 through 3.2.x) - Struct field reference with safety annotations - ViewLord architecture diagram - LockIBase vs Forbid/Permit guidance - Complete library function overview (5 categories) README index updated with enriched article descriptions.
This commit is contained in:
Ilia Sharin
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[← Home](../README.md) · [Intuition](README.md)
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# Gadgets — GadTools and BOOPSI
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# Gadgets
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## Overview
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## What Is a Gadget?
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Intuition gadgets are the UI controls: buttons, string fields, sliders, checkboxes, listviews, etc. OS 2.0+ provides **GadTools** (high-level toolkit) and **BOOPSI** (object-oriented framework).
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A gadget is Intuition's fundamental interactive UI element — the Amiga equivalent of a widget, control, or component. Every button, checkbox, slider, text field, and scrollbar in an Amiga application is a gadget. Gadgets handle their own rendering, hit-testing, and state management, delivering results to the application via [IDCMP](idcmp.md) messages.
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The gadget system evolved through three major generations:
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| Generation | Era | API | Key Feature |
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|---|---|---|---|
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| **Raw Intuition** | 1985 (OS 1.x) | `struct Gadget` + manual imagery | Full control, maximum boilerplate |
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| **GadTools** | 1990 (OS 2.0) | `CreateGadget()` + `NewGadget` | Standard OS look-and-feel with minimal code |
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| **[BOOPSI](boopsi.md)** | 1990 (OS 2.0) | `NewObject()` + OOP dispatchers | Object-oriented, interconnectable, extensible |
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Most applications should use **GadTools** for standard UI or **BOOPSI** for custom behavior. Raw Intuition gadgets are only necessary for OS 1.x compatibility or extreme customization.
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---
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## GadTools Gadget Types
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## Gadget Types
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| Kind | Constant | Description |
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|---|---|---|
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| Button | `BUTTON_KIND` | Simple push button |
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| Checkbox | `CHECKBOX_KIND` | Toggle on/off |
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| Integer | `INTEGER_KIND` | Numeric entry field |
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| Listview | `LISTVIEW_KIND` | Scrollable list |
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| MX | `MX_KIND` | Mutually exclusive (radio buttons) |
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| Number | `NUMBER_KIND` | Read-only number display |
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| Cycle | `CYCLE_KIND` | Pop-up cycle selector |
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| Palette | `PALETTE_KIND` | Colour picker |
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| Scroller | `SCROLLER_KIND` | Scroll bar |
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| Slider | `SLIDER_KIND` | Value slider |
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| String | `STRING_KIND` | Text entry field |
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| Text | `TEXT_KIND` | Read-only text display |
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### System Gadgets
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Built into every window — controlled by `WA_Flags`:
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| Gadget | Flag | IDCMP Event | Description |
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|---|---|---|---|
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| Close | `WFLG_CLOSEGADGET` | `IDCMP_CLOSEWINDOW` | "×" button — window close request |
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| Depth | `WFLG_DEPTHGADGET` | — (handled by Intuition) | Front/back toggle |
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| Zoom | `WFLG_HASZOOM` | — | Alternate-size toggle (OS 2.0+) |
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| Drag | `WFLG_DRAGBAR` | — | Title bar drag area |
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| Size | `WFLG_SIZEGADGET` | `IDCMP_NEWSIZE` | Resize handle |
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### Application Gadgets
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Created by the application and attached to windows:
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| Type | GadTools Kind | Description | IDCMP |
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|---|---|---|---|
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| **Button** | `BUTTON_KIND` | Click action | `IDCMP_GADGETUP` |
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| **Checkbox** | `CHECKBOX_KIND` | Boolean toggle | `IDCMP_GADGETUP` |
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| **Cycle** | `CYCLE_KIND` | Drop-down selector (cycles through options) | `IDCMP_GADGETUP` |
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| **Integer** | `INTEGER_KIND` | Numeric text field | `IDCMP_GADGETUP` |
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| **ListView** | `LISTVIEW_KIND` | Scrollable list of items | `IDCMP_GADGETUP` |
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| **MX** (Mutual Exclude) | `MX_KIND` | Radio button group | `IDCMP_GADGETUP` |
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| **Number** | `NUMBER_KIND` | Read-only numeric display | — |
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| **Palette** | `PALETTE_KIND` | Color picker from screen palette | `IDCMP_GADGETUP` |
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| **Scroller** | `SCROLLER_KIND` | Scrollbar | `IDCMP_GADGETUP` / `MOUSEMOVE` |
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| **Slider** | `SLIDER_KIND` | Horizontal/vertical value slider | `IDCMP_GADGETUP` / `MOUSEMOVE` |
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| **String** | `STRING_KIND` | Text input field | `IDCMP_GADGETUP` |
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| **Text** | `TEXT_KIND` | Read-only text display | — |
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---
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## Creating a GadTools Layout
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## GadTools — Standard Gadget Creation (OS 2.0+)
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### Setup
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GadTools requires a **VisualInfo** handle (ties gadgets to a specific screen's look):
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```c
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#include <libraries/gadtools.h>
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#include <proto/gadtools.h>
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struct Library *GadToolsBase = OpenLibrary("gadtools.library", 39);
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struct Screen *scr = LockPubScreen(NULL);
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APTR vi = GetVisualInfo(scr, TAG_DONE);
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```
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### Creating a Gadget List
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GadTools gadgets are created in a **linked list** using a context pointer:
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```c
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struct Gadget *glist = NULL;
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struct NewGadget ng;
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struct Gadget *gad = CreateContext(&glist);
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struct Gadget *gad;
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ng.ng_LeftEdge = 20;
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ng.ng_TopEdge = 30;
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ng.ng_Width = 100;
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ng.ng_Height = 14;
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ng.ng_GadgetText = "OK";
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ng.ng_GadgetID = 1;
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ng.ng_VisualInfo = vi;
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ng.ng_Flags = 0;
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ng.ng_TextAttr = NULL;
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/* Initialize the context — creates a hidden "anchor" gadget */
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gad = CreateContext(&glist);
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gad = CreateGadget(BUTTON_KIND, gad, &ng, TAG_DONE);
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/* Define gadget layout */
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struct NewGadget ng = {
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.ng_LeftEdge = 20,
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.ng_TopEdge = 30,
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.ng_Width = 200,
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.ng_Height = 14,
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.ng_GadgetText = "Name:",
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.ng_TextAttr = &topaz8,
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.ng_GadgetID = GAD_NAME,
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.ng_Flags = PLACETEXT_LEFT,
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.ng_VisualInfo = vi,
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};
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ng.ng_TopEdge += 20;
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ng.ng_GadgetText = "Cancel";
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ng.ng_GadgetID = 2;
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gad = CreateGadget(BUTTON_KIND, gad, &ng, TAG_DONE);
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/* Open window with gadgets: */
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struct Window *win = OpenWindowTags(NULL,
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WA_Gadgets, glist,
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WA_IDCMP, IDCMP_GADGETUP | IDCMP_CLOSEWINDOW | BUTTONIDCMP,
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/* ... */
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/* String gadget */
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gad = CreateGadget(STRING_KIND, gad, &ng,
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GTST_MaxChars, 64,
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GTST_String, "Default",
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TAG_DONE);
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/* Event loop: */
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/* on IDCMP_GADGETUP: */
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/* struct Gadget *gad = (struct Gadget *)imsg->IAddress; */
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/* switch (gad->GadgetID) { case 1: ... case 2: ... } */
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/* Button below it */
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ng.ng_TopEdge += 20;
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ng.ng_GadgetText = "OK";
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ng.ng_GadgetID = GAD_OK;
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ng.ng_Flags = PLACETEXT_IN;
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/* Cleanup: */
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gad = CreateGadget(BUTTON_KIND, gad, &ng, TAG_DONE);
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/* Attach to window */
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struct Window *win = OpenWindowTags(NULL,
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WA_Title, "GadTools Demo",
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WA_Gadgets, glist, /* Attach gadget list */
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WA_IDCMP, IDCMP_CLOSEWINDOW | IDCMP_GADGETUP |
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IDCMP_REFRESHWINDOW,
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WA_Flags, WFLG_CLOSEGADGET | WFLG_DRAGBAR |
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WFLG_DEPTHGADGET | WFLG_ACTIVATE |
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WFLG_SMART_REFRESH,
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TAG_DONE);
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/* Render gadget borders (required for GadTools!) */
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GT_RefreshWindow(win, NULL);
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```
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### Event Handling
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```c
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struct IntuiMessage *msg;
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while ((msg = GT_GetIMsg(win->UserPort)))
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{
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ULONG class = msg->Class;
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UWORD code = msg->Code;
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struct Gadget *gad = (struct Gadget *)msg->IAddress;
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GT_ReplyIMsg(msg);
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switch (class)
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{
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case IDCMP_GADGETUP:
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switch (gad->GadgetID)
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{
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case GAD_NAME:
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{
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/* Read string value */
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STRPTR name;
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GT_GetGadgetAttrs(gad, win, NULL,
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GTST_String, &name, TAG_DONE);
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Printf("Name: %s\n", name);
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break;
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}
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case GAD_OK:
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running = FALSE;
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break;
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}
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break;
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case IDCMP_REFRESHWINDOW:
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GT_BeginRefresh(win);
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GT_EndRefresh(win, TRUE);
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break;
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}
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}
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```
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### Cleanup
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```c
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/* Order matters: window first, then gadgets, then visual info */
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CloseWindow(win);
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FreeGadgets(glist);
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FreeVisualInfo(vi);
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UnlockPubScreen(NULL, scr);
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CloseLibrary(GadToolsBase);
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```
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---
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## BOOPSI (Basic Object-Oriented Programming System for Intuition)
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## Updating Gadget State at Runtime
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BOOPSI provides class-based gadgets with message dispatch:
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### GadTools Gadgets
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```c
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/* Create a BOOPSI string gadget: */
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Object *strObj = NewObject(NULL, "strgclass",
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GA_Left, 20,
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GA_Top, 50,
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GA_Width, 200,
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GA_Height, 14,
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GA_ID, 3,
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STRINGA_Buffer, myBuffer,
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STRINGA_MaxChars, 64,
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/* Update a slider value */
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GT_SetGadgetAttrs(sliderGad, win, NULL,
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GTSL_Level, 75,
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TAG_DONE);
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/* Add to window: */
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AddGadget(win, (struct Gadget *)strObj, -1);
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RefreshGadgets((struct Gadget *)strObj, win, NULL);
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/* Disable a button */
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GT_SetGadgetAttrs(okGad, win, NULL,
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GA_Disabled, TRUE,
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TAG_DONE);
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/* Cleanup: */
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RemoveGadget(win, (struct Gadget *)strObj);
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DisposeObject(strObj);
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/* Read current value */
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LONG level;
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GT_GetGadgetAttrs(sliderGad, win, NULL,
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GTSL_Level, &level,
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TAG_DONE);
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```
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### Raw Intuition Gadgets
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For non-GadTools gadgets, you must manually remove/re-add to avoid rendering glitches:
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```c
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/* Remove gadget from window */
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UWORD pos = RemoveGadget(win, myGadget);
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/* Modify gadget fields */
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myGadget->Flags |= GFLG_DISABLED;
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/* Re-add at same position */
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AddGadget(win, myGadget, pos);
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/* Refresh the display */
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RefreshGList(myGadget, win, NULL, 1);
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```
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---
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## Raw Intuition Gadgets (struct Gadget)
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For cases where GadTools or BOOPSI are insufficient — direct hardware-level control:
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### struct Gadget
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```c
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struct Gadget {
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struct Gadget *NextGadget; /* Linked list */
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WORD LeftEdge, TopEdge;
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WORD Width, Height;
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UWORD Flags; /* GFLG_* */
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UWORD Activation; /* GACT_* */
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UWORD GadgetType; /* GTYP_* */
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APTR GadgetRender; /* Image or Border for normal state */
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APTR SelectRender; /* Image or Border for selected state */
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struct IntuiText *GadgetText; /* Label */
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LONG MutualExclude;
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APTR SpecialInfo; /* StringInfo, PropInfo, etc. */
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UWORD GadgetID; /* Application-defined ID */
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APTR UserData; /* Application-defined pointer */
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};
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```
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### Gadget Flags (GFLG_*)
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| Flag | Value | Description |
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|---|---|---|
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| `GFLG_GADGHCOMP` | `0x0000` | Highlight by complementing select box |
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| `GFLG_GADGHBOX` | `0x0001` | Highlight by drawing box around gadget |
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| `GFLG_GADGHIMAGE` | `0x0002` | Use `SelectRender` image when selected |
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| `GFLG_GADGHNONE` | `0x0003` | No highlighting |
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| `GFLG_GADGIMAGE` | `0x0004` | `GadgetRender` is `struct Image *`, not `struct Border *` |
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| `GFLG_RELBOTTOM` | `0x0008` | Position relative to bottom edge |
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| `GFLG_RELRIGHT` | `0x0010` | Position relative to right edge |
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| `GFLG_RELWIDTH` | `0x0020` | Width relative to window width |
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| `GFLG_RELHEIGHT` | `0x0040` | Height relative to window height |
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| `GFLG_SELECTED` | `0x0080` | Gadget is currently selected |
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| `GFLG_DISABLED` | `0x0100` | Gadget is grayed out / inactive |
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### Activation Flags (GACT_*)
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| Flag | Value | Description |
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|---|---|---|
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| `GACT_RELVERIFY` | `0x0001` | Send `IDCMP_GADGETUP` only if mouse released inside |
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| `GACT_IMMEDIATE` | `0x0002` | Send `IDCMP_GADGETDOWN` on press |
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| `GACT_ENDGADGET` | `0x0004` | Deactivate requester when gadget released |
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| `GACT_FOLLOWMOUSE` | `0x0008` | Report mouse while gadget is active |
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| `GACT_TOGGLESELECT` | `0x0100` | Toggle selected state on each click |
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| `GACT_LONGINT` | `0x0800` | String gadget contains a long integer |
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### Gadget Types (GTYP_*)
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| Type | Value | SpecialInfo | Description |
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|---|---|---|---|
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| `GTYP_BOOLGADGET` | `0x0001` | — | Simple click button |
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| `GTYP_STRGADGET` | `0x0004` | `struct StringInfo *` | Text input field |
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| `GTYP_PROPGADGET` | `0x0003` | `struct PropInfo *` | Proportional (slider/scrollbar) |
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| `GTYP_CUSTOMGADGET` | `0x0005` | Class-specific | BOOPSI custom class |
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---
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## Proportional (Slider) Gadgets
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Prop gadgets are used for scrollbars and sliders. They have their own state structure:
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```c
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struct PropInfo {
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UWORD Flags; /* AUTOKNOB, FREEHORIZ, FREEVERT */
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UWORD HorizPot; /* Horizontal position (0–0xFFFF) */
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UWORD VertPot; /* Vertical position (0–0xFFFF) */
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UWORD HorizBody; /* Horizontal knob size (0–0xFFFF) */
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UWORD VertBody; /* Vertical knob size (0–0xFFFF) */
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/* ... internal fields ... */
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};
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/* Calculate body size for a scrollbar:
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visible = number of visible items
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total = total number of items */
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UWORD body = (visible >= total) ? MAXBODY
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: (UWORD)((ULONG)MAXBODY * visible / total);
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/* Calculate pot (position) from current top item:
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top = first visible item index */
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UWORD pot = (total <= visible) ? 0
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: (UWORD)((ULONG)MAXPOT * top / (total - visible));
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```
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---
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## String Gadgets
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Text input gadgets use `StringInfo`:
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```c
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UBYTE buffer[128] = "Default text";
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UBYTE undoBuffer[128];
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struct StringInfo si = {
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.Buffer = buffer,
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.UndoBuffer = undoBuffer,
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.BufferPos = 0,
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.MaxChars = sizeof(buffer),
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};
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/* Read the result after GADGETUP: */
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Printf("User entered: %s\n", si.Buffer);
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```
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With GadTools, this is much simpler:
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```c
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gad = CreateGadget(STRING_KIND, gad, &ng,
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GTST_MaxChars, 128,
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GTST_String, "Default text",
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TAG_DONE);
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```
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---
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## Relative Positioning
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Gadgets can be positioned relative to window edges — they automatically move when the window resizes:
|
||||
|
||||
```c
|
||||
/* Scrollbar on the right edge */
|
||||
myGadget.LeftEdge = -16; /* 16 pixels from right */
|
||||
myGadget.TopEdge = 0;
|
||||
myGadget.Width = 16;
|
||||
myGadget.Height = -16; /* Extends to 16px from bottom */
|
||||
myGadget.Flags = GFLG_RELRIGHT | GFLG_RELHEIGHT;
|
||||
```
|
||||
|
||||
| Flag | Effect |
|
||||
|---|---|
|
||||
| `GFLG_RELRIGHT` | `LeftEdge` is offset from right edge (use negative values) |
|
||||
| `GFLG_RELBOTTOM` | `TopEdge` is offset from bottom edge |
|
||||
| `GFLG_RELWIDTH` | `Width` is added to window width |
|
||||
| `GFLG_RELHEIGHT` | `Height` is added to window height |
|
||||
|
||||
---
|
||||
|
||||
## Pitfalls
|
||||
|
||||
### 1. Forgetting GT_RefreshWindow
|
||||
|
||||
GadTools gadgets won't render properly without the initial `GT_RefreshWindow(win, NULL)` call. The window appears to have no gadgets.
|
||||
|
||||
### 2. Using GetMsg Instead of GT_GetIMsg
|
||||
|
||||
GadTools internally sends messages for gadget sub-events (e.g., ListView scrolling). Using `GetMsg()` directly breaks GadTools' internal state machine.
|
||||
|
||||
### 3. Modifying Gadgets Without Remove/Add
|
||||
|
||||
Changing a raw gadget's position, flags, or imagery while it's attached to a window causes rendering corruption. Always `RemoveGadget()` → modify → `AddGadget()` → `RefreshGList()`.
|
||||
|
||||
### 4. Not Setting GACT_RELVERIFY
|
||||
|
||||
Without `GACT_RELVERIFY`, the application never receives `IDCMP_GADGETUP`. The gadget appears to "eat" clicks silently.
|
||||
|
||||
### 5. String Gadget Buffer Overrun
|
||||
|
||||
The `MaxChars` field includes the null terminator. If your buffer is 64 bytes, set `MaxChars` to 64 (not 63). The gadget handles null termination.
|
||||
|
||||
---
|
||||
|
||||
## Best Practices
|
||||
|
||||
1. **Use GadTools** for standard UI — it provides the correct OS look-and-feel automatically
|
||||
2. **Use `GT_GetIMsg()`/`GT_ReplyIMsg()`** — never mix raw `GetMsg()` with GadTools
|
||||
3. **Always call `GT_RefreshWindow()`** after opening a window with GadTools gadgets
|
||||
4. **Free in reverse order**: `CloseWindow()` → `FreeGadgets()` → `FreeVisualInfo()` → `UnlockPubScreen()`
|
||||
5. **Use `GA_Disabled`** to gray out gadgets instead of removing them — maintains layout stability
|
||||
6. **Set `PLACETEXT_LEFT/RIGHT/ABOVE`** for label placement — don't hardcode text positions
|
||||
7. **Handle `IDCMP_REFRESHWINDOW`** with `GT_BeginRefresh()`/`GT_EndRefresh()`
|
||||
8. **Give every gadget a unique `GadgetID`** — this is how you identify the source in `IDCMP_GADGETUP`
|
||||
|
||||
---
|
||||
|
||||
## References
|
||||
|
||||
- NDK39: `libraries/gadtools.h`, `intuition/classusr.h`
|
||||
- ADCD 2.1: `CreateGadget`, `CreateContext`, `GetVisualInfo`
|
||||
- NDK 3.9: `intuition/intuition.h`, `intuition/gadgetclass.h`, `libraries/gadtools.h`
|
||||
- ADCD 2.1: `CreateGadget()`, `GT_SetGadgetAttrs()`, `GT_GetGadgetAttrs()`
|
||||
- AmigaOS Reference Manual (RKRM): Libraries, Chapter 7 — Gadgets
|
||||
- See also: [BOOPSI](boopsi.md), [IDCMP](idcmp.md), [Windows](windows.md)
|
||||
|
|
|
|||
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