UI slider module

ui slider module extends ui base with slider ui element.

Enable ui base with uiSli and create a slider with callback on untouch:

var ui = require("ui")       // load ui base module
      .adx(require("uiSli")) // add uiSli module into base and remove from cache

Create - specify - a slider

var s2 = // hold on to "s2" slider ui element for direct access app later on.
//    0   1    2       3   4   5   6   7   8  9      10  11
// flgs  clazz id      x   y   w   h  bc fcs  valObj cb,  ls (arr of labels ([[...],..]))
//       sli                ->x2->y2                    [0] fs tc    x  y  txt fmt
ui.c( 3,"sli","s2"  , 30,175,180, 29, -4,[-4,0],33  ,cb,  [[12, 6,  70, 6,   u,
                                                           ,function(v,_,l){ // (val,ui,lab)
        var s="", f=_.te.f; return (!(f==0 || f&184)) ? s : ((v<1)?"0":"") // 128+32+16+8
                       +(s=_.mr(v*10)+"%").substr(0,s.length-2)+"."+s.substr(-2); }// val
//                         _.mr()=Math.round()               min max si  o a flgs
                                                             -10, 10,[3] 0 1  168
//                                                           left top right bot margins
                                                            ,   6,  3,    5,  0
//                                                      [>0] fs tc   x  y  label text
                                                           ,[12, 7,-25, 6, "%:0"] // frnt
                                                           ,[12, 7,182, 6, "100"] // back

Above example definition creates, adds to ui, and returns (and stores in global variable s2 ) a 0..100% horizontal slider of 3 pixel change value touch / drag s(ensitivity) with left top at x and y (30, 175) and of h(eight) and w(idth) (180,29), with custom colored border (-4) and same colored 'left' filling and black colored (0) 'right' filling, with start value 33 (%) within min (0) and max (100) range and 3 respective labels with own font specs (fs, all 12), text colors (tc, 6 and 7) and positions (by fixed x and y offset from left top showing custom formatted value (in center), "%:0" on the left and "100", on the right, with bit coded single value callback activation touch event flags filter (flgs: 168), with not value-based adjustment (a: 0) of color and position of value label, with extra margins - left and right for easy min / max setting by touch (left:6, right:5) - top (3) for drawing within bounding box ticks (and values) taller than 1 pixel, and no extra margin at the bottom (bot: 0).

Two more examples:

// Simple horizontal slider "s1":
//    0  1     2       3   4   5   6   7   8  9       10  11                         12
// flgs  clazz id      x   y   w   h  bc fcs  value   cb, ls (arr labels [[...],..]) ca
//       sli                ->x2->y2                    [0] fs tc    x  y  txt fmt
ui.c( 3,"sli","s1"  , 10,145,220, 26,  6,[ 4, 1],0,   cb, [[ u, u,   u, u, u,    0
//                                                          min max si
                                                          , -10,100,[0]);

// Fully loaded vertical slider "s5":
//....0  1     2       3   4   5   6   7   8  9       10  11                         12
//.flgs  clazz id      x   y   w   h  bc fcs  value   cb, ls (arr of labels [[...],..])
//.......sli                ->x2->y2                    [0] fs tc    x  y  txt fmt
ui.c( 3,"sli","s5"  , 10,150, 55,170,  2,[ 4, 1], 4,  cb, [[14, 6,   6, u, "v" // y val dep
     ,function(v,_,l){ // value,ui,label passed for value dependent modification...
      var s="",y, f=_.te.f; if (f===0 || f&184) { // update label only at 0 and 128+32+16+8
      s=((_.mu(s=_.mr(v))<10)?" ":"")+((s<0)?s:"+"+s)+l[4]; // ./ label y pos val dependent
      l[3]=(((y=_.mr(170/2-v*(170-2-2-5-5)/(10-(-10)))-18)>=2+5+3)?y:y+23); }
      return s; } // value dependent display location of value label (a top of bar level)
// orientation o: 0=horizontal, 1=vertical                 min max si  o a flgs
                                                          ,-10, 10,[3],1,0, 168
// margins for ticks and easy min / max tap area            left top right bot margins
                                                           ,   0,  5,    5,  5]
// minimum, maximum labels relative to left top corner [>0] fs tc   x   y  txt fmt
                                                          ,[10, 4, 80 , 1, "max"]
                                                          ,[10, 1, 83,156, "min"]

sli ui element constructor arguments (a[]) and runtime data structure (e[]) are:

arg runtime 'object' instance of 'clazz' slider
a[]  e[]
 0   [0] f   - flags focus(4), active(2), visible(1)
 .    .         0bxx1 visible &1 visible
 .    .          0bx1x active  &2 active / senses touches vs read/display-only
 .    .          0b1xx focus   &4 focus by touch down, drag w/in bounding box
 1   [1] c   - clazz - "rad"
 2   [2] id  - eg "s02", short, at least 3 chars, and ui globally unique
               Single letter ui element ids are 'reserved' (for keyboard(s)).
 3   [3] x   - x ((left ) of focus / touch bounding box)
 4   [4] y   - y ((top  ) of focus / touch bounding box)
 5       w   - width (of focus / touch box,...
     [5] x2  - x ((right) of focus / touch bounding box: x - w + 1)
 6       h   - height (of focus / touch box,...
     [6] y2  - y ((bot  ) of focus / touch bounding box: y - h + 1)
 7   [7] bc  - border color
 8   [8] fcs - fill colors array
         [0] fill color for 'left side' of slider
         [1] fill color for 'right side' of slider
 9   [9] v  - value - a number
10  [10] cb - callback on touch, value change, untouch
11  [11] ls - labels - array of labels of which first one is value related
      ls[0] label (info) for value related info, array with:
         l[0]  fs - font spec:s>0: fontVector (size); s<0: .fnts[-s] of loaded font
         l[1]  tc - (label) text color (index)
         l[2]  x  - x offset from focus box x ( bounding box left )
         l[3]  y  - y offset from focus box y ( bounding box top  )
         l[4]  tx - value label text available for formatter function
         l[5]  fm - optional function to format/change value label/parms
         l[6]  mn - minimum value ( at left  border )
         l[7]  mx - maximum value ( at right border )
         l[8]  si - sensitivity information
           si[0] s - sensitivity (in pixels to detect change and redraw)
         l[9]  o  - opt. orientation falsy: horizontal, else vertical slider
         l[10] a  - opt. value adjusted label pos and color (for B&W, 2-clrs)
         l[11] flgs - flags define on what touch events label is rendered
         l[12] ml - opt. margin left for extra min touch area (part of w)
         l[13] mt - opt. margin top for ticks or a-alike (part of h)
         l[14] mr - opt. margin right for extra  min touch area (part of w)
         l[15] mb - opt. margin bottom for ticks or a-alike (part of h)
      ls[1,2,3,...] any number of additional labels, mostly just 2 (min,max)
         l[0]  fs - font spec:s>0: fontVector (size); s<0: .fnts[-s] of loaded font
         l[1]  tc - (label) text color (index)
         l[2]  x  - x offset from focus box x ( bounding box left )
         l[3]  y  - y offset from focus box y ( bounding box top  )
         l[4]  tx - label text to display (using .drawString())
         l[5]  fm - opt. formatter function(l[4],_,l)

Above examples custom formatter does one decimal rounding on value and appends percent sign ( 50.6% ). Flags define on what touch event(s) the value label is rendered.

Custom formatter has dual purpose:

  • Render more than just the bare (numeric) value.
  • Simplified custom formatted numeric value (rounded, less digits).
  • Render discrete text values based on numeric value, such as "high", "medium" and "low" alone or combined with (formatted) numeric value.
  • Placing a visual - value labe or any other thing - alone or in combination with (formatted) value anywhere on the display with value derivced position and color and form and shape and...
  • Avoid slowing down sliding by suppressing rendering on some of the touch events. When value label's font spec ( fs / l[0] / ls[0][0]` ) is *NOT* `undefined, value label rendering gets invoked on virtually all occurring touch events and leaves it to the application to skip - by returning empty string.
  • Provide a hook for the application to render (and/or do) what ever extra ordinary thing the application requires based on different values reached when visualizing these values with (most likely read-only / display-only, not active bit displayed) sliders by updating them with these values using one of these avenues (when no other touch is going on, otherwise it has to be deferred with a timeout / queued):
    • invoke ui update method with respective arguments:
      • ui.u(sliderEltIdxOrIdOrInstance, value, 1); (1 for 'propagate' change / update event).
    • invoke ui event method with x and y with the right values simulating a touch down and then and then invoke with no arguments to simulate an untouch:
      • ui.evt(x,y);ui.evt(); .

Because rendering - drawing strings on a display - can be slow, rendering the actual value while sliding has to be kept to a minimum to keep sliding snappy. Providing the formatter function that returns an non-empty string only on desired conditions and an empty one else does the trick: rendering an empty string is not noticeably slowing down sliding; ui element value (v), ui and touch event states / flags (, .te.f) can be used to form the desired condition to return empty or not empty string.

Note that the custom formatter ([l[13] of first label - ls[0]) is called before value label is drawn. This allows the custom formatter not only to define what is rendered, but also how and where it is rendered by just-in-time setting/modifying the passed label's parameters and do other extraordinary things (like coloring or clearing a alert zone).

Label parameters useful to modify just-in-time for drawing the label are:

  • l[0] fs - font spec: vectorFont size (>0), (loaded) bit map font (<=0)
  • l[1] tc - text color: single coded value (>=0) or from palette (<0)
  • l[2] x - x relative to bounding box left side (x of ui element def)
  • l[3] y - y relative to bounding box top side (y of ui element def)
  • l[6] s - sensitivity - for value / change/time dependent adjustment
  • l[8] a - adjust (value based <>50%) vs fix label color and position
  • l[13] itself, the custom formatter (for the next label drawing).

No working guarantee is given for changing other label parameters than the one listed above.

Just-in-time setting parameters for the value label to draw helps when either fixed specified ( l[8] = 0 or absent) or fix combined with value-based, out-of-box adjusted ( l[8] = 1) colors and position do just not fit the ui's needs or aren't looking right (After all it is UX and and the ui has to look at be usable at its best). To avoid value-based adjustment of color and position after setting parameters, define the slider ui element with 0 for a / l[8] / ls[0][8] (like for fixed specified color and postion).

With value-based auto adjustment (a) of value label's color and position enabled - value of ( a / l[8] / ls[0][8] ) is set to ( 1 ) - drawing position is adjusted a third of the slider bar width to the left when slider value is >= 50% (half an upper half), otherwise to the right (when the slider is <50%, lower half), and the color of the labe takes on the opposite fill color. Specifying another non-0 value than `1` does it proportionally less ( `<1` ) or more ( `>1). Best results are easiest achieved when drawn label length is around a third of the actual slider bar. Longer labels may need label parameters set to custom calculated placement and color in custom formatter and with value-based auto adjustment 'turned of' (set to0` ).

A real estate saving trick on small displays and keeping the actual slider bar as wide as possible is to use the space of the left and right labels - if present - for the extra padding for easy minimum and maximum touching area. Note that the extra margins are part of the width of the bounding box, so labels left and right of the actual slider bar lay inside the bounding box and their x and y are different from what they are when positioned outside of the bounding box.

Ticks drawing is part of the extra drawings function that can be passed at initial or re-display of all items or whole display by the ui base draw function ui.d(undefined,extraDrawingsFunction) or - for short either ui.d(0,...) or ui.d(u,...) (with variable u defined for undefined, or when custom (re-)drawing individual slider ui element e with ui.d(e,tickDrawingFunction). For convenience (and more so for performance), ui ( _ ) and slider ui element ( e ) are passed to the extra_or_tick_drawings(_,e) function. Note the extra margin for the ticks are part of the height of the bounding box. You either increase the slider ui elements h(eight) or you accept a slim slider bar. Slim slider bars may though not anymore accommodate a label value, which - under some circumstances - may not be an issue because of not added value or (accurate,) numeric value is not needed. Btw, custom formatter can return text values, such as "high", "medium", "low" instead of numeric values... or combined with numeric values). Last but not least the value label can be drawen anywhere on the display with the respective 'fix' x and y relative to the left top of the bounding box ('fix', 0 for the auto value-based adjustment of position and color value label 111a / l[8] / ls[0][8]``` may be recommended if not otherwise desired, such as 'moving target'-a-like and limited control over the color. Both 'moving target' AND full control over color can be achieved by setting label parameters in custom formatter function).

Colors are bit-coded with 3-bit color-depth according ui.clrs=[...] setup.

Since slider has two (2) areas to fill - left and right side of slider - fill colors - fcs - are specified as array:

  • fcs[0] is fill color for the 'left' / 'filled' side of the slider.
  • fcs[1] is fill color for the 'right' / 'empty' side of the slider.

Since slider has drag aspects callback and should also be able to deliver values to the application while sliding, callback conditions can be specified by flags as defined for the ui event flags. These flags also control whether the new changed value is set and custom formatter function is invoked or not. On untouch though, the new value is and formatter is invoked no matter whether the untouch flag(s) is(are) set or not.

Callback is called with id, v, ui, e, t as arguments:

args[] sym   description
  0    id  : button id ("c01")
  1    v   : value object (usually a number)
  2    ui  : ui (THE ui object)
  3    e   : uiSli element (sli 'object' (runtime data structure))
  4    t   : touch info x, y,... (where last touched)
        { x : x coordinate
        , y : y coordinate
        , t : touched (truey) / untouched (falsey)
        , f : flags

For detailed ui setup, including color depth and custom colors, connecting to display and touch screen, soft key board or buttons, see ui module and example material (in the ui.zip file and sources with comments). Take a look at the example that shows all ui elements on one single display - uiExampleAll.js - project file in the _sbx Espruino sandbox projects folder. Make it the Espruino Web IDE sandbox folder and run the ready-made examples on your Espruino board. Espruino forum has several entries about the modules and hardware. Search in (google) for: Espruino Forum allObjects touch screen display modular ui framework

No board or display with touch screen yet? No Problem: Open uiExample.html in uidev folder in Web browser to run the same example in the Cross Development / Emulation environment (where modules are developed and maintained).

For helpful details to use the ui base and ui element APIs, take a look at documentation in ui base and uiBtn modules.

sli - slider ui element properties - variables and methods - mixed into ui base:

exports = // sli (slider) ui element ('clazz' name).
// ...
// ... private variables and methods
// ...


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