// widget_dropdown.ysl2

template "widget[@type='DropDown']", mode="widget_defs" {

param "hmi_element";

labels("text box button");

||

dispatch: function(value) {

if(!this.opened) this.set_selection(value);

},

init: function() {

this.button_elt.setAttribute("onclick", "hmi_widgets['«$hmi_element/@id»'].on_button_click()");

// Save original size of rectangle

this.box_bbox = this.box_elt.getBBox()

// Compute margins

text_bbox = this.text_elt.getBBox()

lmargin = text_bbox.x - this.box_bbox.x;

tmargin = text_bbox.y - this.box_bbox.y;

this.margins = [lmargin, tmargin].map(x => Math.max(x,0));

// It is assumed that list content conforms to Array interface.

this.content = [

``foreach "arg" | "«@value»",

];

// Index of first visible element in the menu, when opened

this.menu_offset = 0;

// How mutch to lift the menu vertically so that it does not cross bottom border

this.lift = 0;

// Event handlers cannot be object method ('this' is unknown)

// as a workaround, handler given to addEventListener is bound in advance.

this.bound_close_on_click_elsewhere = this.close_on_click_elsewhere.bind(this);

this.opened = false;

},

// Called when a menu entry is clicked

on_selection_click: function(selection) {

this.close();

this.apply_hmi_value(0, selection);

},

on_button_click: function() {

this.open();

},

on_backward_click: function(){

this.scroll(false);

},

on_forward_click:function(){

this.scroll(true);

},

set_selection: function(value) {

let display_str;

if(value >= 0 && value < this.content.length){

// if valid selection resolve content

display_str = this.content[value];

this.last_selection = value;

} else {

// otherwise show problem

display_str = "?"+String(value)+"?";

}

// It is assumed that first span always stays,

// and contains selection when menu is closed

this.text_elt.firstElementChild.textContent = display_str;

},

grow_text: function(up_to) {

let count = 1;

let txt = this.text_elt;

let first = txt.firstElementChild;

// Real world (pixels) boundaries of current page

let bounds = svg_root.getBoundingClientRect();

this.lift = 0;

while(count < up_to) {

let next = first.cloneNode();

// relative line by line text flow instead of absolute y coordinate

next.removeAttribute("y");

next.setAttribute("dy", "1.1em");

// default content to allow computing text element bbox

next.textContent = "...";

// append new span to text element

txt.appendChild(next);

// now check if text extended by one row fits to page

// FIXME : exclude margins to be more accurate on box size

let rect = txt.getBoundingClientRect();

if(rect.bottom > bounds.bottom){

// in case of overflow at the bottom, lift up one row

let backup = first.getAttribute("dy");

// apply lift asr a dy added too first span (y attrib stays)

first.setAttribute("dy", "-"+String((this.lift+1)*1.1)+"em");

rect = txt.getBoundingClientRect();

if(rect.top > bounds.top){

this.lift += 1;

} else {

// if it goes over the top, then backtrack

// restore dy attribute on first span

if(backup)

first.setAttribute("dy", backup);

else

first.removeAttribute("dy");

// remove unwanted child

txt.removeChild(next);

return count;

}

}

count++;

}

return count;

},

close_on_click_elsewhere: function(e) {

// inhibit events not targetting spans (menu items)

if(e.target.parentNode !== this.text_elt){

e.stopPropagation();

// close menu in case click is outside box

if(e.target !== this.box_elt)

this.close();

}

},

close: function(){

// Stop hogging all click events

svg_root.removeEventListener("click", this.bound_close_on_click_elsewhere, true);

// Restore position and sixe of widget elements

this.reset_text();

this.reset_box();

// Put the button back in place

this.element.appendChild(this.button_elt);

// Mark as closed (to allow dispatch)

this.opened = false;

// Dispatch last cached value

this.apply_cache();

},

// Set text content when content is smaller than menu (no scrolling)

set_complete_text: function(){

let spans = this.text_elt.children;

let c = 0;

for(let item of this.content){

let span=spans[c];

span.textContent = item;

span.setAttribute("onclick", "hmi_widgets['«$hmi_element/@id»'].on_selection_click("+c+")");

c++;

}

},

// Move partial view :

// false : upward, lower value

// true : downward, higher value

scroll: function(forward){

let contentlength = this.content.length;

let spans = this.text_elt.children;

let spanslength = spans.length;

// reduce accounted menu size according to jumps

if(this.menu_offset != 0) spanslength--;

if(this.menu_offset < contentlength - 1) spanslength--;

if(forward){

this.menu_offset = Math.min(

contentlength - spans.length + 1,

this.menu_offset + spanslength);

}else{

this.menu_offset = Math.max(

0,

this.menu_offset - spanslength);

}

this.set_partial_text();

},

// Setup partial view text content

// with jumps at first and last entry when appropriate

set_partial_text: function(){

let spans = this.text_elt.children;

let contentlength = this.content.length;

let spanslength = spans.length;

let i = this.menu_offset, c = 0;

while(c < spanslength){

let span=spans[c];

// backward jump only present if not exactly at start

if(c == 0 && i != 0){

span.textContent = "↑ ↑ ↑";

span.setAttribute("onclick", "hmi_widgets['«$hmi_element/@id»'].on_backward_click()");

// presence of forward jump when not right at the end

}else if(c == spanslength-1 && i < contentlength - 1){

span.textContent = "↓ ↓ ↓";

span.setAttribute("onclick", "hmi_widgets['«$hmi_element/@id»'].on_forward_click()");

// otherwise normal content

}else{

span.textContent = this.content[i];

span.setAttribute("onclick", "hmi_widgets['«$hmi_element/@id»'].on_selection_click("+i+")");

i++;

}

c++;

}

},

open: function(){

let length = this.content.length;

// systematically reset text, to strip eventual whitespace spans

this.reset_text();

// grow as much as needed or possible

let slots = this.grow_text(length);

// Depending on final size

if(slots == length) {

// show all at once

this.set_complete_text();

} else {

// eventualy align menu to current selection, compensating for lift

let offset = this.last_selection - this.lift;

if(offset > 0)

this.menu_offset = Math.min(offset + 1, length - slots + 1);

else

this.menu_offset = 0;

// show surrounding values

this.set_partial_text();

}

// Now that text size is known, we can set the box around it

this.adjust_box_to_text();

// Take button out until menu closed

this.element.removeChild(this.button_elt);

// Rise widget to top by moving it to last position among siblings

this.element.parentNode.appendChild(this.element.parentNode.removeChild(this.element));

// disable interaction with background

svg_root.addEventListener("click", this.bound_close_on_click_elsewhere, true);

// mark as open

this.opened = true;

},

// Put text element in normalized state

reset_text: function(){

let txt = this.text_elt;

let first = txt.firstElementChild;

// remove attribute eventually added to first text line while opening

first.removeAttribute("onclick");

first.removeAttribute("dy");

// keep only the first line of text

for(let span of Array.from(txt.children).slice(1)){

txt.removeChild(span)

}

},

// Put rectangle element in saved original state

reset_box: function(){

let m = this.box_bbox;

let b = this.box_elt;

b.x.baseVal.value = m.x;

b.y.baseVal.value = m.y;

b.width.baseVal.value = m.width;

b.height.baseVal.value = m.height;

},

// Use margin and text size to compute box size

adjust_box_to_text: function(){

let [lmargin, tmargin] = this.margins;

let m = this.text_elt.getBBox();

let b = this.box_elt;

b.x.baseVal.value = m.x - lmargin;

b.y.baseVal.value = m.y - tmargin;

b.width.baseVal.value = 2 * lmargin + m.width;

b.height.baseVal.value = 2 * tmargin + m.height;

},

||

}