slabOS/lib/basalt/objects/Scrollbar.lua

local tHex = require("tHex")

return function(name, basalt)
    local base = basalt.getObject("VisualObject")(name, basalt)
    local objectType = "Scrollbar"

    base:setZIndex(2)
    base:setSize(1, 8)
    base:setBackground(colors.lightGray, "\127", colors.gray)

    local barType = "vertical"
    local symbol = " "
    local symbolBG = colors.black
    local symbolFG = colors.black
    local scrollAmount = 3
    local index = 1
    local symbolSize = 1
    local symbolAutoSize = true

    local function updateSymbolSize()
        local w,h = base:getSize()
        if(symbolAutoSize)then
            symbolSize = math.max((barType == "vertical" and h or w-(#symbol)) - (scrollAmount-1), 1)
        end
    end
    updateSymbolSize()

    local function mouseEvent(self, button, x, y)
    local obx, oby = self:getAbsolutePosition()
    local w,h = self:getSize()
        updateSymbolSize()
        local size = barType == "vertical" and h or w
        for i = 0, size do
            if ((barType == "vertical" and oby + i == y) or (barType == "horizontal" and obx + i == x)) and (obx <= x) and (obx + w > x) and (oby <= y) and (oby + h > y) then
                index = math.min(i + 1, size - (#symbol + symbolSize - 2))
                self:scrollbarMoveHandler()
                self:updateDraw()
            end
        end
    end

    local object = {
        getType = function(self)
            return objectType
        end,

        load = function(self)
            base.load(self)
            local parent = self:getParent()
            self:listenEvent("mouse_click")
            self:listenEvent("mouse_up")
            self:listenEvent("mouse_scroll")
            self:listenEvent("mouse_drag")
        end,

        setSymbol = function(self, _symbol, bg, fg)
            symbol = _symbol:sub(1,1)
            symbolBG = bg or symbolBG
            symbolFG = fg or symbolFG
            updateSymbolSize()
            self:updateDraw()
            return self
        end,

        setSymbolBG = function(self, bg)
            return self:setSymbol(symbol, bg, nil)
        end,

        setSymbolFG = function(self, fg)
            return self:setSymbol(symbol, nil, fg)
        end,

        getSymbol = function(self)
            return symbol
        end,

        getSymbolBG = function(self)
            return symbolBG
        end,

        getSymbolFG = function(self)
            return symbolFG
        end,

        setIndex = function(self, _index)
            index = _index
            if (index < 1) then
                index = 1
            end
            local w,h = self:getSize()
            --index = math.min(index, (barType == "vertical" and h or w) - (symbolSize - 1))
            updateSymbolSize()
            self:updateDraw()
            return self
        end,

        setScrollAmount = function(self, amount)
            scrollAmount = amount
            updateSymbolSize()
            self:updateDraw()
            return self
        end,

        getScrollAmount = function(self)
            return scrollAmount
        end,

        getIndex = function(self)
            local w,h = self:getSize()
            return scrollAmount > (barType=="vertical" and h or w) and math.floor(scrollAmount/(barType=="vertical" and h or w) * index) or index
        end,

        setSymbolSize = function(self, size)
            symbolSize = tonumber(size) or 1
            symbolAutoSize = size~=false and false or true
            updateSymbolSize()
            self:updateDraw()
            return self
        end,

        getSymbolSize = function(self)
            return symbolSize
        end,

        setBarType = function(self, _typ)
            barType = _typ:lower()
            updateSymbolSize()
            self:updateDraw()
            return self
        end,

        getBarType = function(self)
            return barType
        end,

        mouseHandler = function(self, button, x, y, ...)
            if (base.mouseHandler(self, button, x, y, ...)) then
                mouseEvent(self, button, x, y)
                return true
            end
            return false
        end,

        dragHandler = function(self, button, x, y)
            if (base.dragHandler(self, button, x, y)) then
                mouseEvent(self, button, x, y)
                return true
            end
            return false
        end,

        setSize = function(self, ...)
            base.setSize(self, ...)
            updateSymbolSize()
            return self
        end,

        scrollHandler = function(self, dir, x, y)
            if(base.scrollHandler(self, dir, x, y))then
                local w,h = self:getSize()
                updateSymbolSize()
                index = index + dir
                if (index < 1) then
                    index = 1
                end
                index = math.min(index, (barType == "vertical" and h or w) - (barType == "vertical" and symbolSize - 1 or #symbol+symbolSize-2))
                self:scrollbarMoveHandler()
                self:updateDraw()
            end
        end,

        onChange = function(self, ...)
            for _,v in pairs(table.pack(...))do
                if(type(v)=="function")then
                    self:registerEvent("scrollbar_moved", v)
                end
            end
            return self
        end,


        scrollbarMoveHandler = function(self)
            self:sendEvent("scrollbar_moved", self:getIndex())
        end,

        customEventHandler = function(self, event, ...)
            base.customEventHandler(self, event, ...)
            if(event=="basalt_FrameResize")then
                updateSymbolSize()
            end 
        end,

        draw = function(self)
            base.draw(self)
            self:addDraw("scrollbar", function()
                local parent = self:getParent()
                local w,h = self:getSize()
                local bgCol,fgCol = self:getBackground(), self:getForeground()
                if (barType == "horizontal") then
                    for n = 0, h - 1 do
                        self:addBlit(index, 1 + n, symbol:rep(symbolSize), tHex[symbolFG]:rep(#symbol*symbolSize), tHex[symbolBG]:rep(#symbol*symbolSize))
                    end
                elseif (barType == "vertical") then
                    for n = 0, h - 1 do
                        if (index == n + 1) then
                            for curIndexOffset = 0, math.min(symbolSize - 1, h) do
                                self:addBlit(1, index + curIndexOffset, symbol:rep(math.max(#symbol, w)), tHex[symbolFG]:rep(math.max(#symbol, w)), tHex[symbolBG]:rep(math.max(#symbol, w)))
                            end
                        end
                    end
                end
            end)
        end,
    }

    object.__index = object
    return setmetatable(object, base)
end