a2d/MGTK.md

# MouseGraphics ToolKit

This is a complex API library written by Apple circa 1985. It consists of:

* [Graphics Primitives](#graphics-primitives) - screen management, lines, rects, polys, text, patterns, pens
  * [Concepts](#concepts)
  * [Commands](#commands)
* [Mouse Graphics](#mouse-graphics) - windows, menus, events, cursors
  * [Concepts](#concepts-1)
  * [Commands](#commands-1)
* [Creating Applications and DeskTop Desk Accessories](#creating-applications-and-desktop-desk-accessories)

For the purposes of DeskTop, the entry point is fixed at $4000 AUX, called MLI-style:
```
    JSR $4000
    .byte call
    .addr params
```
Result will be in A, with Z bit set, 0 indicating success (so `BNE error` works).

ca65 syntax is used for primitives: `.byte`, `.word` (interpreted as 16-bit signed integer), `.addr` (16-bit address), `.res N` (N byte buffer)

---

# Graphics Primitives

## Concepts

### Point
```
.word       xcoord
.word       ycoord
```

### Rect
```
.word       x1
.word       y1
.word       x2
.word       y2
```

### Pattern
A simple repeating 8x8 pattern is defined by 8 bytes. All bits of each byte are used.
```
.byte       row0
.byte       row1
.byte       row2
.byte       row3
.byte       row4
.byte       row5
.byte       row6
.byte       row7
```

### MapInfo
Used with GrafPorts to define offsets/clipping, and bitmaps for source data.
```
Point       viewloc
.addr       mapbits         $2000 for the screen, or bitmap bits
.byte       mapwidth        $80, or stride for bitmap
.byte       reserved
Rect        maprect         a.k.a. cliprect
```

### GrafPort
There is always a current GrafPort (or "port" for short) that defines
the destination and pen state of drawing operations.
```
MapInfo     portmap
Pattern     penpattern
.byte       colormask_and
.byte       colormask_or
Point       penloc
.byte       penwidth        horizontal pen thickness
.byte       penheight       vertical pen thickness
.byte       penmode
.byte       textback        text background
.addr       textfont
```

### PolyList
```
.byte       count           number of vertices in this polygon
.byte       last            high bit set if there are more polygons
Point       vertex0
... repeats for each vertex
... repeats for each polygon
```

### Font
This is a MousePaint-compatible font. Single- and double-width fonts are
supported; max height is 16 pixels.
```
.byte       fonttype        0=regular, $80=double-width
.byte       lastchar        char code of last character (usually $7F)
.byte       height          pixels (1-16)
.res N      charwidth       pixels, for each char
.res N      row0            bits
.res N      row0right       bits (double-width only)
... repeats for each row
```

## Commands

#### NoOp ($00)
No-op

No parameters.

### Initialization

#### InitGraf ($01)
No parameters.

#### SetSwitches ($02)
Configure display switches

Parameters:
```
 .byte       flags           bit 0=hires, 1=page2, 2=mixed, 3=text
```

### GrafPort - assign, update, query ports

#### InitPort ($03)
Initialize GrafPort to standard values

Parameters:
```
(input is address of GrafPort record)
```

#### SetPort ($04)
Set current port as specified

Parameters:
```
(input is address of GrafPort record)
```

#### GetPort ($05)
Get pointer to current port

Parameters:
```
.addr       port            (out)
```

#### SetPortBits ($06)
Set just the mapinfo (viewloc, mapbits) of the current grafport.

Parameters:
```
(input is address of MapInfo record)
```

#### SetPenMode ($07)
Set the pen mode of the current grafport.

Parameters:
```
.byte       mode            pen*/notpen*
```

#### SetPattern ($08)
Set the pattern of the current grafport.

Parameters:
```
.res 8      pattern         8x8 pixel pattern for PaintRect calls
```

#### SetColorMasks ($09)
Set the color masks of the current grafport.

Parameters:
```
.byte       and_mask
.byte       or_mask
```

#### SetPenSize ($0A)
Set the pen size of the current grafport.

Parameters:
```
.byte       penwidth        horizontal pen thickness
.byte       penheight       vertical pen thickness
```

#### SetFont ($0B)
Set the font of the current grafport.

Parameters:
```
.addr       textfont        font definition
```

#### SetTextBG ($0C)
Set the text background of the current grafport.

Parameters:
```
.byte       backcolor       0=black, $7F=white
```

### Drawing - draw lines; frame, fill, and test rects and polys

#### Move ($0D)
Set pen location (relative) of the current grafport.

Parameters:
```
.word       xdelta
.word       ydelta
```

#### MoveTo ($0E)
Set pen location (absolute) of the current grafport.

Parameters:
```
Point        pos
```

#### Line ($0F)
Draw line from pen location (relative) of the current grafport.

Parameters:
```
.word       xdelta
.word       ydelta
```

#### LineTo ($10)
Draw line from pen location (absolute) of the current grafport.

Parameters:
```
Point       pos
```

#### PaintRect ($11)
Fill rectangle with pattern of the current grafport.

Parameters:
```
Rect        rect
```

#### FrameRect ($12)
Draw rectangle with pen mode/size of the current grafport.

Parameters:
```
Rect        rect
```

#### InRect ($13)
Is current position in bounds? A=$80 true, 0 false

Parameters:
```
Rect        rect
```

#### PaintBits ($14)
Draw bitmap.

Parameters:
```
(input is address of MapInfo record)
```

#### PaintPoly ($15)
Fill multiple closed polygons with the pattern of the current grafport.

Parameters:
```
(input is address of PolyList record)
```

#### FramePoly ($16)
Draw multiple closed polygons with the pen mode/size of the current grafport.

Parameters:
```
(input is address of PolyList record)
```

#### InPoly ($17)
Is pen location of the current grafport within the polygon? A=$80 true, 0 false

Parameters:
```
(input is address of PolyList record)
```

### Text - draw and measure text


#### TextWidth ($18)
Measure the width of a string in pixels

Parameters:
```
.addr       data
.byte       length
.word       width           (out) result in pixels
```

#### DrawText ($19)
Draw string at the pen location of the current graphport (as left, baseline)

Parameters:
```
.addr       data
.byte       length
```

### Utility - configuration and version

#### SetZP1 ($1A)
Configure lower half of ZP usage by API (speed vs. convenience)

Parameters:
```
.byte       preserve        0=stash/no auto restore; 1=restore now and onward
```

#### SetZP2 ($1B)
Configure upper half ZP usage by API (speed vs. convenience)

Parameters:
```
.byte       preserve        0=stash/no auto restore; 1=restore now and onward
```


---

# Mouse Graphics

## Concepts

### Cursor
```
.res 24     bitmap          2x12 byte bitmap (XOR'd after mask)
.res 24     mask            2x12 byte mask (OR'd with screen)
.byte       hotx            hotspot coords (pixels)
.byte       hoty
```

### Event
```
.byte       kind            event_kind_*
.res 4
```
if `kind` is `event_kind_key_down`:
```
.byte       kind            event_kind_*
.byte       key             (ASCII code; high bit clear)
.byte       modifiers       (0=none, 1=open-apple, 2=solid-apple, 3=both)
.res 2      reserved
```
if `kind` is `event_kind_update:`
```
.byte       kind            event_kind_*
.byte       window_id
.res 3      reserved
```
otherwise:
```
.byte       kind            event_kind_*
.word       mousex
.word       mousey
```

```
event_kind_no_event        = 0    ; No mouse or keypress
event_kind_button_down     = 1    ; Mouse button was depressed
event_kind_button_up       = 2    ; Mouse button was released
event_kind_key_down        = 3    ; Key was pressed
event_kind_drag            = 4    ; Mouse button still down
event_kind_apple_key       = 5    ; Mouse button was depressed, modifier key down
event_kind_update          = 6    ; Window update needed

event_modifier_open_apple  = 1 << 0
event_modifier_solid_apple = 1 << 1
```

### Menu

Menu Bar record:
```
.word       count           Number of menu bar items

.byte       menu_id         Menu identifier
.byte       disabled        Flag
.addr       title           Address of length-prefixed string
.addr       menu            Address of Menu record
.res 6      reserved        Reserved
... repeats for each menu
```

Menu record:
```
.word       count           Number of items in menu

.res  5     reserved        Reserved
.byte       options         bit 0=OA, 1=SA, 2=mark, 5=check, 6=filler, 7=disabled
.byte       mark_char       Custom mark character if mark option set
.byte       char1           ASCII code of shortcut #1 (e.g. uppercase B); or 0
.byte       char2           ASCII code of shortcut #2 (e.g. lowercase b, or same); or 0
.addr       name            Address of length-prefixed string
... repeats for each menu item
```

### Window "winfo"
```
.byte       id
.byte       options         option_*
.addr       title
.byte       hscroll         scroll_option_*
.byte       vscroll         scroll_option_*
.byte       hthumbmax
.byte       hthumbpos
.byte       vthumbmax
.byte       vthumbpos
.byte       status
.byte       reserved
.word       mincontwidth    minimum content size (horizontal)
.word       mincontlength   minimum content size (vertical)
.word       maxcontwidth    maximum content size (horizontal)
.word       maxcontlength   maximum content size (vertical)
GrafPort    windowport      GrafPort record
.addr       nextwinfo       address of next lower window in stack
```

Windows have a _content area_ which has the requested dimensions. Above this is an optional
_title bar_ which in turn has an optional _close box_. Within the content area are an
optional _resize box_ and optional _scroll bars_.

```
option_dialog_box       = 1 << 0
option_go_away_box      = 1 << 1
option_grow_box         = 1 << 2

scroll_option_none      = 0
scroll_option_present   = 1 << 7
scroll_option_thumb     = 1 << 6
scroll_option_active    = 1 << 0
scroll_option_normal    = scroll_option_present | scroll_option_thumb | scroll_option_active
```
## Commands

### Initialization

#### Version ($1C)
Get toolkit version

Parameters:
```
.byte       (out) major
.byte       (out) minor
.byte       (out) patch
.byte       (out) status
.word       (out) number
```

#### StartDeskTop ($1D)
Inits state, registers interrupt handler, draws desktop

Parameters:
```
.byte       machine         ROM FBB3 ($06 = IIe or later)
.byte       subid           ROM FBC0 ($EA = IIe, $E0 = IIe enh/IIgs, $00 = IIc/IIc+)
.byte       op_sys          0=ProDOS, 1=Pascal
.byte       slot_num:       Mouse slot, 0 = search (will be filled in)
.byte       use_interrupts  0=passive, 1=interrupt
.addr       sysfontptr
.addr       savearea        buffer for saving screen data (e.g. behind menus)
.word       savesize        bytes
```

#### StopDeskTop ($1E)
Deallocates interrupt, hides cursor

No parameters.

#### SetUserHook ($1F)


Parameters:
```
.byte       hook_id         0=before, 1=after event checking
.addr       routine_ptr     0=remove hook_id
```

#### AttachDriver ($20)
Install pointer driver; A=0 on success, $95 if mouse disabled

Parameters:
```
.addr       hook            Mouse hook routine to install
.addr       mouse_state     (out) Address of mouse state (.word x, y; .byte status)
```

#### ScaleMouse ($21)
Set mouse/screen scaling

Parameters:
```
.byte       x_exponent      x-scale factor for mouse, 0...3
.byte       y_exponent      y-scale factor for mouse, 0...3
```

#### KeyboardMouse ($22)
Next operation will be performed by keyboard

No parameters.

#### GetIntHandler ($23)
Get address of interrupt handler

Parameters:
```
.addr       handler         (out) Address of interrupt handler (after cld)
```


### Cursor Manager - set, show, hide

#### SetCursor ($24)
Set cursor definition

Parameters:
```
(input is address of Cursor record)
```

#### ShowCursor ($25)
Return cursor to visibility

No parameters.

#### HideCursor ($26)
Cursor hidden until ShowCursor call

No parameters.

#### ObscureCursor ($27)
Cursor hidden until moved

No parameters.

#### GetCursorAddr ($28)
Get cursor definition

Parameters:
```
.addr definition            (out) Address of cursor record
```

### Event Manager - get, peek, post

#### CheckEvents ($29)
Process mouse/kbd if GetEvent will be delayed.

No parameters.

#### GetEvent ($2A)


Parameters:
```
(parameter is address of Event record)
```

#### FlushEvents ($2B)


No parameters.

#### PeekEvent ($2C)


Parameters:
```
(parameter is address of Event record)
```

#### PostEvent ($2D)
Post event to queue

Parameters:
```
(parameter is address of Event record)
```

#### SetKeyEvent ($2E)
If set, keypresses are ignored by Tool Kit

Parameters:
```
.byte       handle_keys     high bit set = ignore keyboard, otherwise check
```


### Menu Manager - configure, enable, disable, select

#### InitMenu ($2F)
Configure characters used for menu glyphs. Optional. The defaults
are solid=$1E, open=$1F, check=$1D, control=$01.

Parameters:
```
.byte       solid_char      char code to use for solid apple glyph
.byte       open_char       char code to use for open apple glyph
.byte       check_char      char code to use for checkmark glyph
.byte       control_char    char code to use for control key glyph
```

#### SetMenu ($30)
Configure (and draw) menu

Parameters:
```
(input is address of Menu Bar record)
```

#### MenuSelect ($31)
Enter modal loop for handling mouse-down on menu bar

Parameters:
```
.byte       menu_id         (out) Top level menu identifier, or 0 if none
.byte       menu_item       (out) Index (1-based) of item in menu, or 0 if none
```

#### MenuKey ($32)
Find menu item corresponding to keypress

Parameters:
```
.byte       menu_id         (out)
.byte       menu_item       (out)
.byte       which_key
.byte       key_mods        bit 0=OA, bit 1=SA
```

#### HiliteMenu ($33)
Toggle highlight state of menu

Parameters:
```
.byte       menu_id
```

#### DisableMenu ($34)
Disable/enable a menu. Effectively disables all items, but individual disable/enable states are restored when re-enabled.

Parameters:
```
.byte       menu_id
.byte       disable         0=enable, 1=disable
```

#### DisableItem ($35)
Disable/enable a specific item in a menu.

Parameters:
```
.byte       menu_id
.byte       menu_item
.byte       disable         0=enable, 1=disable
```

#### CheckItem ($36)
Sets a specific menu item as checked.

Parameters:
```
.byte       menu_id
.byte       menu_item
.byte       check           0=unchecked, 1=checked
```

#### SetMark ($37)
Sets a specific menu item as using a distinct mark character when checked.

Parameters:
```
.byte       menu_id
.byte       menu_item
.byte       set_char        0=use checkmark, 1=use mark_char
.byte       mark_char       char code to use for mark
```


### Window Manager - open, close, drag, grow, update

#### OpenWindow ($38)


Parameters:
```
(input is address of WInfo record)
```

#### CloseWindow ($39)


Parameters:
```
.byte window_id
```

#### CloseAll ($3A)


No parameters.

#### GetWinPtr ($3B)
Get pointer to window params by id; A=0 on success

Parameters:
```
.byte       window_id
.addr       window_ptr      (out) winfo address
```

#### GetWinPort ($3C)
Populate GrafPort with current drawing state of window, clipped if the window is partially offscreen.

Parameters:
```
.byte       window_id
.addr       port            address of GrafPort to populate
```

Returns `error_window_obscured` if the content area of the window is completely offscreen and drawing should be skipped. (The port rect will be invalid.)


#### SetWinPort ($3D)
Update port of window

Parameters:
```
.byte       window_id
.addr       port            GrafPort to copy from
```


#### BeginUpdate ($3E)
Respond to update event for window

Parameters:
```
.byte       window_id
```

#### EndUpdate ($3F)


No parameters.

#### FindWindow ($40)


Parameters:
```
.word       mousex          screen coordinates
.word       mousey
.byte       which_area      (out) area_*
.byte       window_id       (out) of window
```

#### FrontWindow ($41)
Get id of top window

Parameters:
```
.byte       window_id       (out) window, or 0 if none
```

#### SelectWindow ($42)
Make window topmost

Parameters:
```
.byte       window_id
```

#### TrackGoAway ($43)


Parameters:
```
.byte       clicked         (out) 0 = cancelled, 1 = close
```

#### DragWindow ($44)


Parameters:
```
.byte       window_id
.word       dragx           mouse coords
.word       dragy
.byte       moved           (out) high bit set if moved, clear if not
```


#### GrowWindow ($45)


Parameters:
```
.byte       window_id
.word       mousex
.word       mousey
.byte       itgrew          (out) 0 = no change, 1 = moved
```

#### ScreenToWindow ($46)
Map screen coords to content coords

Parameters:
```
.byte       window_id
.word       screenx
.word       screeny
.word       windowx         (out)
.word       windowy         (out)
```

#### WindowToScreen ($47)
Map content coords to screen coords

Parameters:
```
.byte       window_id
.word       windowx
.word       windowy
.word       screenx         (out)
.word       screeny         (out)
```


### Control Manager - scrollbars

#### FindControl ($48)


Parameters:
```
.word       mousex
.word       mousey
.byte       which_ctl       ctl_*
.byte       which_part      part_*
```

#### SetCtlMax ($49)


Parameters:
```
.byte       which_ctl       ctl_*_scroll_bar
.byte       ctlmax          maximum value
```

#### TrackThumb ($4A)


Parameters:
```
.byte       which_ctl       ctl_*_scroll_bar
.word       mousex
.word       mousey
.byte       thumbpos        (out) 0...255
.byte       thumbmobed      (out) 0 = no change, 1 = moved
```


#### UpdateThumb ($4B)


Parameters:
```
.byte       which_ctl       ctl_*_scroll_bar
.byte       thumbpos        new position 0...250
```

#### ActivateCtl ($4C)
Activate/deactivate scroll bar

Parameters:
```
.byte       which_ctl       ctl_*_scroll_bar
.byte       activate        0=deactivate, 1=activate
```

# Creating Applications and DeskTop Desk Accessories

### Application Use

_Notes specific to DeskTop Desk Accessories (DA) are included where usage differs._

#### Initialization

* `StartDeskTop`
* `InitMenu` (if necessary; the defaults are sensible)
* `SetMenu`
* Run main loop until quit
* `StopDeskTop`


#### Main Loop

* `GetEvent`
* If `event_kind_button_down` or `event_kind_apple_key`:
   * `FindWindow` to figure out what was clicked
   * If `area_desktop` - ignore
   * If `area_menubar` - handle menu
   * If `area_dragbar` - [handle window drag](#handle-window-drag)
   * If `area_grow_box` - [handle window resize](#handle-window-resize)
   * If `area_close_box` - [handle window close](#handle-window-close)
   * If `area_content`:
     * `FindControl`
     * If `ctl_*_scroll_bar` - [handle scrolling](#handle-scrolling)
     * If `ctl_dead_zone` - ignore
     * If `ctl_not_a_control`:
       * If not topmost:
         * `SelectWindow`
       * Otherwise, handle content click per app
* If `event_kind_key_down` - [handle key](#handle-key)
* If `event_kind_drag`:
  * TODO
* If `event_kind_update`:
   * [Redraw](#redraw-window) contents of `window_id`


#### Redraw window

* `GetWinPort` - populate a local GrafPort with an appropriately clipped port
* if `error_window_obscured` is returned, abort these steps (port will be invalid)
* `SetPort` - make it current
* optional: `HideCursor` - if multiple drawing calls will be made
* ... draw ...
* optional: `ShowCursor` - if it was hidden above
* optional: `SetWinPort` - save changed attributes (penpos, etc) if desired


#### Handle Key

* `MenuKey`
* If `menu_id` is not 0:
  * Dispatch for `menu_id` and `menu_item`
  * `HiliteMenu` to toggle state back off when done
* Otherwise:
  * handle key press per app

_DA specific: Menus are not supported in DAs, so the first steps here can be skipped._


#### Handle Menu

* `MenuSelect` to initiate menu modal loop
* If `menu_id` is 0, done
* Dispatch for `menu_id` and `menu_item`
* `HiliteMenu` to toggle state back off when done

_DA specific: Menus are not supported in DAs._


#### Handle Window Drag

* `SelectWindow` to make topmost if necessary
* `DragWindow` to initiate drag modal loop
* [Handle update events](#handle-update-events)
* [Redraw](#redraw-window) window content if not moved and was made topmost

_DA specific: Use the following steps instead:_

* `DragWindow` to initiate drag modal loop
* If not `moved` - done
* Call `JUMP_TABLE_REDRAW_ALL` so DeskTop can redraw its windows
* [Redraw](#redraw-window) window content
* Call `DESKTOP_REDRAW_ICONS` so DeskTop can redraw the desktop (volume) icons


#### Handle Window Close

* `TrackGoAway` to initiate modal close loop
* If canceled - done
* `CloseWindow`


#### Handle Scrolling

* If `part_thumb`:
  * `TrackThumb` to initiate modal scroll loop
  * If thumb did not move - done
  * [Redraw](#redraw-window) window content
  * `UpdateThumb`
* If `part_page_*`:
  * Scroll by a "page"
  * [Redraw](#redraw-window) window content
  * `UpdateThumb`
* If `part_*_arrow`:
  * Scroll by a "line"
  * [Redraw](#redraw-window) window content
  * `UpdateThumb`


#### Handle Window Resize

* `GrowWindow` to initiate modal resize loop
* If canceled - done
* `UpdateThumb` if needed to adjust scroll bars
* [Redraw](#redraw-window) window content

_DA specific:_

In addition to the above steps:
* Call `JUMP_TABLE_REDRAW_ALL` _before_ redrawing the DA window.
* Call `DESKTOP_REDRAW_ICONS` _after_ redrawing the DA window.


#### Handle Update Events

* Repeat:
  * `PeekEvent`
  * If not `event_kind_update` - exit these steps
  * Otherwise:
    * `GetEvent`
    * `BeginUpdate`
    * If error, continue
    * Otherwise:
      * [Redraw](#redraw-window) `window_id`'s content
      * `EndUpdate`

_DA specific: Update events are not used._