benilla-octo/crates/benilla-app/assets/ui/ScrollTemplates.xml

<Ui>
    <!--
        Benilla's scroll parts: a `Slider` bar with its arrow helpers, an optional trough, and a
        real-scroll kit that pans a `<ScrollFrame>` child whose height is known only after layout.
        Faux lists use the stock `FauxScrollFrameTemplate`; this file declares only `Benilla` names.
        A real-scroll bar overrides the template's OnValueChanged on its instance, which wins
        because the loader runs every `<Scripts>` block in order.
    -->
    <Script><![CDATA[
        -- One valueStep per step, where the reference's arrows and wheel move half the bar
        -- (UIPanelTemplates.xml:137/149, UIPanelTemplates.lua:150-157).
        -- Soundless: the reference plays UChatScrollButton on an arrow click, never on the wheel.
        function BenillaScrollBar_Step(scrollBar, dir)
            local step = scrollBar:GetValueStep()
            if step <= 0 then step = 1 end
            scrollBar:SetValue(scrollBar:GetValue() + dir * step)
        end

        -- Greys each arrow at its end of the range (reference: ScrollFrame_OnScrollRangeChanged).
        function BenillaScrollBar_UpdateArrows(scrollBar)
            local minV, maxV = scrollBar:GetMinMaxValues()
            local val = scrollBar:GetValue()
            local up = getglobal(scrollBar:GetName() .. "ScrollUpButton")
            local down = getglobal(scrollBar:GetName() .. "ScrollDownButton")
            if val <= minV then up:Disable() else up:Enable() end
            if val >= maxV then down:Disable() else down:Enable() end
        end

        -- The value is pixels in steps of a row; the parent holds the 0-based top row in
        -- `frame.offset` and its repaint in `frame.updateFunc`, which runs only when that row
        -- changes, so a repaint that re-seats the thumb ends the loop. A ScrollFrame parent also
        -- gets SetVerticalScroll, as UIPanelTemplates.xml:156-158 routes it.
        function BenillaFauxScrollBar_OnValueChanged(scrollBar, value)
            local frame = scrollBar:GetParent()
            local step = scrollBar:GetValueStep()
            if step <= 0 then step = 1 end
            local newOffset = floor(value / step + 0.5)
            if newOffset ~= frame.offset then
                frame.offset = newOffset
                if frame.updateFunc then frame.updateFunc() end
            end
            BenillaScrollBar_UpdateArrows(scrollBar)
            if frame.SetVerticalScroll then frame:SetVerticalScroll(value) end
        end

        -- ReputationFrame's hang, 8 left, 21 above, 20 below (ReputationFrame.xml:573-599 against
        -- UIPanelTemplates.xml:166-181). Lazy: the bar does not exist at the trough's OnLoad.
        function BenillaScrollTrough_Seat(trough, scrollBar)
            if trough.seated then return end
            trough.seated = true
            trough:ClearAllPoints()
            trough:SetPoint("TOPLEFT", scrollBar, "TOPLEFT", -8, 21)
            trough:SetPoint("BOTTOMRIGHT", scrollBar, "BOTTOMRIGHT", 7, -20)
        end

        -- Show and hide a bar only through here, so its `<barname>Trough` follows.
        function BenillaScrollBar_SetShown(scrollBar, shown)
            local trough = getglobal(scrollBar:GetName() .. "Trough")
            if trough then BenillaScrollTrough_Seat(trough, scrollBar) end
            if shown then
                scrollBar:Show()
                if trough then trough:Show() end
            else
                scrollBar:Hide()
                if trough then trough:Hide() end
            end
        end

        -- For a stock `FauxScrollFrameTemplate` frame; call after `FauxScrollFrame_Update`.
        function BenillaScrollTrough_Follow(scrollFrameName)
            local sf = getglobal(scrollFrameName)
            if not sf then return end
            local bar = getglobal(scrollFrameName .. "ScrollBar")
            if not bar then return end
            local trough = getglobal(bar:GetName() .. "Trough")
            if not trough then return end
            BenillaScrollTrough_Seat(trough, bar)
            if sf:IsShown() then trough:Show() else trough:Hide() end
        end

        -- One row per wheel notch (+1 up), from the owner window's OnMouseWheel; the reference's
        -- `ScrollFrameTemplate_OnMouseWheel` moves half the bar.
        function BenillaFauxScrollFrame_OnMouseWheel(frame, delta)
            local scrollBar = getglobal(frame:GetName() .. "ScrollBar")
            BenillaScrollBar_Step(scrollBar, -delta)
        end

        -- ══════════════════════════ The real-scroll kit ══════════════════════════════════════════
        -- Shaped on UIPanelTemplates.xml:166-211: the bar is the `Slider` child `$parentBar`.
        BENILLA_SCROLL_STEP = 20   -- px per arrow click or wheel notch
        BENILLA_SCROLL_PAD = 20    -- px of room below the child's last element

        -- The loop back through SyncBar ends in one hop: Slider:SetValue ignores an equal value.
        function BenillaScrollBar_OnValueChanged(bar, value)
            bar:GetParent():SetVerticalScroll(value)
            BenillaScrollBar_UpdateArrows(bar)
        end

        -- Hides the bar when the content fits (reference: ScrollFrame_OnScrollRangeChanged).
        function BenillaScroll_SyncBar(sf)
            local bar = getglobal(sf:GetName() .. "Bar")
            if not bar then return end
            local range = sf:GetVerticalScrollRange()
            bar:SetValueStep(BENILLA_SCROLL_STEP)
            bar:SetMinMaxValues(0, range)
            bar:SetValue(sf:GetVerticalScroll())
            BenillaScrollBar_UpdateArrows(bar)
            BenillaScrollBar_SetShown(bar, range > 0)
        end

        -- Clamped here: SetVerticalScroll stores any value, as the reference's does.
        function BenillaScroll_Step(sf, delta)
            local target = sf:GetVerticalScroll() + delta
            local range = sf:GetVerticalScrollRange()
            if target > range then target = range end
            if target < 0 then target = 0 end
            sf:SetVerticalScroll(target)
            BenillaScroll_SyncBar(sf)
        end

        -- The wheel's delta is +1 per notch up, and up scrolls toward the top.
        function BenillaScroll_OnMouseWheel(sf, delta)
            BenillaScroll_Step(sf, -delta * BENILLA_SCROLL_STEP)
        end

        -- Nil if hidden, a blank FontString, or not laid out yet.
        function BenillaScroll_WidgetBottom(w)
            if not w then return nil end
            if w.IsShown then
                if not w:IsShown() then return nil end
            elseif w.GetText then
                local t = w:GetText()
                if not t or t == "" then return nil end
            end
            return w:GetBottom()
        end

        -- Rects resolve after Lua runs, so owners re-run this from OnUpdate; it writes only on a
        -- real change, since SetHeight invalidates layout.
        function BenillaScroll_ResizeChild(scrollName, widgets)
            local sf = getglobal(scrollName)
            -- Not a derived name: the reference pairs `<X>ScrollFrame` with `<X>ScrollChildFrame`.
            local child = sf:GetScrollChild()
            if not child then return false end
            local top = child:GetTop()
            if not top then return false end
            local bottom = nil
            for i = 1, table.getn(widgets) do
                local b = BenillaScroll_WidgetBottom(getglobal(widgets[i]))
                if b and (not bottom or b < bottom) then bottom = b end
            end
            local height = 1
            if bottom then height = (top - bottom) + BENILLA_SCROLL_PAD end
            if height < 1 then height = 1 end
            if math.abs(child:GetHeight() - height) < 1 then return false end
            child:SetHeight(height)
            sf:UpdateScrollChildRect()
            return true
        end
    ]]></Script>

    <!-- The stock scrollbar art cropped to its centred 16px, as `UIPanelScrollBarButton` does. -->
    <Slider name="BenillaScrollBarTemplate" virtual="true">
        <Size><AbsDimension x="16" y="0"/></Size>
        <Frames>
            <Button name="$parentScrollUpButton">
                <Size><AbsDimension x="16" y="16"/></Size>
                <Anchors><Anchor point="BOTTOM" relativePoint="TOP"/></Anchors>
                <NormalTexture file="Interface\Buttons\UI-ScrollBar-ScrollUpButton-Up"><TexCoords left="0.25" right="0.75" top="0.25" bottom="0.75"/></NormalTexture>
                <PushedTexture file="Interface\Buttons\UI-ScrollBar-ScrollUpButton-Down"><TexCoords left="0.25" right="0.75" top="0.25" bottom="0.75"/></PushedTexture>
                <DisabledTexture file="Interface\Buttons\UI-ScrollBar-ScrollUpButton-Disabled"><TexCoords left="0.25" right="0.75" top="0.25" bottom="0.75"/></DisabledTexture>
                <HighlightTexture file="Interface\Buttons\UI-ScrollBar-ScrollUpButton-Highlight" alphaMode="ADD"><TexCoords left="0.25" right="0.75" top="0.25" bottom="0.75"/></HighlightTexture>
                <Scripts><OnClick>BenillaScrollBar_Step(this:GetParent(), -1); PlaySound("UChatScrollButton")</OnClick></Scripts>
            </Button>
            <Button name="$parentScrollDownButton">
                <Size><AbsDimension x="16" y="16"/></Size>
                <Anchors><Anchor point="TOP" relativePoint="BOTTOM"/></Anchors>
                <NormalTexture file="Interface\Buttons\UI-ScrollBar-ScrollDownButton-Up"><TexCoords left="0.25" right="0.75" top="0.25" bottom="0.75"/></NormalTexture>
                <PushedTexture file="Interface\Buttons\UI-ScrollBar-ScrollDownButton-Down"><TexCoords left="0.25" right="0.75" top="0.25" bottom="0.75"/></PushedTexture>
                <DisabledTexture file="Interface\Buttons\UI-ScrollBar-ScrollDownButton-Disabled"><TexCoords left="0.25" right="0.75" top="0.25" bottom="0.75"/></DisabledTexture>
                <HighlightTexture file="Interface\Buttons\UI-ScrollBar-ScrollDownButton-Highlight" alphaMode="ADD"><TexCoords left="0.25" right="0.75" top="0.25" bottom="0.75"/></HighlightTexture>
                <Scripts><OnClick>BenillaScrollBar_Step(this:GetParent(), 1); PlaySound("UChatScrollButton")</OnClick></Scripts>
            </Button>
        </Frames>
        <Scripts>
            <OnValueChanged>BenillaFauxScrollBar_OnValueChanged(self, arg1)</OnValueChanged>
        </Scripts>
        <ThumbTexture name="$parentThumbTexture" file="Interface\Buttons\UI-ScrollBar-Knob">
            <Size><AbsDimension x="16" y="16"/></Size>
            <TexCoords left="0.25" right="0.75" top="0.25" bottom="0.75"/>
        </ThumbTexture>
    </Slider>

    <!--
        A bar's trough, drawn per window in 1.12. Declare it before its bar, named
        `<barname>Trough`, with no anchors. `UI-Character-ScrollBar` holds two 31-wide pieces,
        the left capped at the top, the right at the bottom.
        Deviation: a three-slice where the reference overlaps two quads, since two quads reach
        only 362 units and a page here is 563 tall.
        The fill is ItemTextFrame's 0.8-alpha black; fill and art are in separate layers because
        the client orders overlapping quads within one layer by texture handle.
    -->
    <Frame name="BenillaScrollTroughTemplate" virtual="true" hidden="true">
        <Size><AbsDimension x="31"/></Size>
        <Layers>
            <Layer level="BACKGROUND">
                <!-- The channel interior, inset 6 from each edge of the 31-wide piece. -->
                <Texture name="$parentFill">
                    <Anchors>
                        <Anchor point="TOPLEFT"><Offset><AbsDimension x="6" y="0"/></Offset></Anchor>
                        <Anchor point="BOTTOMRIGHT"><Offset><AbsDimension x="-6" y="0"/></Offset></Anchor>
                    </Anchors>
                    <Color r="0" g="0" b="0" a="0.8"/>
                </Texture>
            </Layer>
            <Layer level="BORDER">
                <!-- Left column, rows 0..22: the cap, the up-arrow socket and a crossbar. -->
                <Texture name="$parentTop" file="Interface\PaperDollInfoFrame\UI-Character-ScrollBar">
                    <Size><AbsDimension y="23"/></Size>
                    <Anchors>
                        <Anchor point="TOPLEFT"/>
                        <Anchor point="TOPRIGHT"/>
                    </Anchors>
                    <TexCoords left="0" right="0.484375" top="0" bottom="0.08984375"/>
                </Texture>
                <!-- Right column, ending on v 0.421875 as ReputationFrame's does. -->
                <Texture name="$parentBottom" file="Interface\PaperDollInfoFrame\UI-Character-ScrollBar">
                    <Size><AbsDimension y="26"/></Size>
                    <Anchors>
                        <Anchor point="BOTTOMLEFT"/>
                        <Anchor point="BOTTOMRIGHT"/>
                    </Anchors>
                    <TexCoords left="0.515625" right="1.0" top="0.3203125" bottom="0.421875"/>
                </Texture>
                <!-- Declared last: an anchor to a later sibling falls back to the parent. -->
                <Texture name="$parentMiddle" file="Interface\PaperDollInfoFrame\UI-Character-ScrollBar">
                    <Anchors>
                        <Anchor point="TOPLEFT" relativeTo="$parentTop" relativePoint="BOTTOMLEFT"/>
                        <Anchor point="BOTTOMRIGHT" relativeTo="$parentBottom" relativePoint="TOPRIGHT"/>
                    </Anchors>
                    <TexCoords left="0" right="0.484375" top="0.1171875" bottom="0.2734375"/>
                </Texture>
            </Layer>
        </Layers>
    </Frame>

</Ui>