zz-plugin.lua

local api = ...

local M = {}

local size
local active_scroller, next_scroller

local function Scroller(items, font, speed)
    local total_w = 0
    for _, item in ipairs(items) do
        total_w = total_w + item.width
    end

    local function draw(now, y, x1, x2)
        local x = math.floor(x1 + (now * -speed) % total_w - total_w)
        local idx = 1
        
        local render = 0
        while x < x2 do
            local item = items[idx]
            if x + item.width < x1 then
                -- skip: not on screen
            else
                local a = item.color.a
                if item.blink then
                    a = math.min(1, 1-math.sin(now*10)) * a
                end
                render = render + 1
                font:write(
                    x, y, item.text, size,
                    item.color.r, item.color.g, item.color.b, a
                )
            end
            x = x + item.width
            idx = idx + 1
            if idx > #items then
                idx = 1
            end
        end
    end

    return draw
end

active_scroller = Scroller({})

function M.updated_config_json(config)
    local items = {}
    for idx = 1, #config.texts do
        local item = config.texts[idx]
        local color = config.color
        if item.color.a ~= 0 then
            color = item.color
        end

        -- 'show' either absent or true?
        if item.show ~= false then
            items[#items+1] = {
                text = item.text,
                blink = item.blink,
                color = color,
            }
            items[#items+1] = {
                text = "   -   ",
                blink = false,
                color = config.color,
            }
        end
    end
    if #items == 0 then
        items[#items+1] = {
            text = "                  ",
            blink = false,
            color = config.color,
        }
    end
    size = config.size
    local font = resource.load_font(api.localized(
        config.font.asset_name
    ))
    for _, item in ipairs(items) do
        item.width = font:width(item.text, size)
    end
    active_scroller = Scroller(
        items, font, config.speed
    )
    print("configured scroller content")
end

local function instance(ctx)
    local function layout(canvas)
        local pos = ctx.child_config.pos or 'bottom'
        local overlap = ctx.child_config.overlap or 'overlap'
        if overlap == 'overlap' then
            return canvas:full()
        elseif pos == 'bottom' then
            return canvas:cut('bottom', size)
        else
            return canvas:cut('top', size)
        end
    end
    local function draw(canvas, target)
        local pos = ctx.child_config.pos or 'bottom'
        local y
        if pos == "bottom" then
            y = target.y2 - size
        else
            y = target.y1
        end
        active_scroller(api.wall_time(), y, target.x1, target.x2)
    end

    return {
        layout = layout;
        draw = draw;
    }
end

function M.init(ctx)
    return instance(ctx)
end

return M