amiga-bootcamp/09_intuition/gadgets.md

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[← Home](../README.md) · [Intuition](README.md)
# Gadgets — GadTools and BOOPSI
## Overview
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).
---
## GadTools Gadget Types
| Kind | Constant | Description |
|---|---|---|
| Button | `BUTTON_KIND` | Simple push button |
| Checkbox | `CHECKBOX_KIND` | Toggle on/off |
| Integer | `INTEGER_KIND` | Numeric entry field |
| Listview | `LISTVIEW_KIND` | Scrollable list |
| MX | `MX_KIND` | Mutually exclusive (radio buttons) |
| Number | `NUMBER_KIND` | Read-only number display |
| Cycle | `CYCLE_KIND` | Pop-up cycle selector |
| Palette | `PALETTE_KIND` | Colour picker |
| Scroller | `SCROLLER_KIND` | Scroll bar |
| Slider | `SLIDER_KIND` | Value slider |
| String | `STRING_KIND` | Text entry field |
| Text | `TEXT_KIND` | Read-only text display |
---
## Creating a GadTools Layout
```c
struct Screen *scr = LockPubScreen(NULL);
APTR vi = GetVisualInfo(scr, TAG_DONE);
struct Gadget *glist = NULL;
struct NewGadget ng;
struct Gadget *gad = CreateContext(&glist);
ng.ng_LeftEdge = 20;
ng.ng_TopEdge = 30;
ng.ng_Width = 100;
ng.ng_Height = 14;
ng.ng_GadgetText = "OK";
ng.ng_GadgetID = 1;
ng.ng_VisualInfo = vi;
ng.ng_Flags = 0;
ng.ng_TextAttr = NULL;
gad = CreateGadget(BUTTON_KIND, gad, &ng, TAG_DONE);
ng.ng_TopEdge += 20;
ng.ng_GadgetText = "Cancel";
ng.ng_GadgetID = 2;
gad = CreateGadget(BUTTON_KIND, gad, &ng, TAG_DONE);
/* Open window with gadgets: */
struct Window *win = OpenWindowTags(NULL,
WA_Gadgets, glist,
WA_IDCMP, IDCMP_GADGETUP | IDCMP_CLOSEWINDOW | BUTTONIDCMP,
/* ... */
TAG_DONE);
/* Event loop: */
/* on IDCMP_GADGETUP: */
/* struct Gadget *gad = (struct Gadget *)imsg->IAddress; */
/* switch (gad->GadgetID) { case 1: ... case 2: ... } */
/* Cleanup: */
CloseWindow(win);
FreeGadgets(glist);
FreeVisualInfo(vi);
UnlockPubScreen(NULL, scr);
```
---
## BOOPSI (Basic Object-Oriented Programming System for Intuition)
BOOPSI provides class-based gadgets with message dispatch:
```c
/* Create a BOOPSI string gadget: */
Object *strObj = NewObject(NULL, "strgclass",
GA_Left, 20,
GA_Top, 50,
GA_Width, 200,
GA_Height, 14,
GA_ID, 3,
STRINGA_Buffer, myBuffer,
STRINGA_MaxChars, 64,
TAG_DONE);
/* Add to window: */
AddGadget(win, (struct Gadget *)strObj, -1);
RefreshGadgets((struct Gadget *)strObj, win, NULL);
/* Cleanup: */
RemoveGadget(win, (struct Gadget *)strObj);
DisposeObject(strObj);
```
---
## References
- NDK39: `libraries/gadtools.h`, `intuition/classusr.h`
- ADCD 2.1: `CreateGadget`, `CreateContext`, `GetVisualInfo`