Scrollable Auto-Resizing Layout Frame

ScrollableResizeLayoutFrame.lua

local ContentFrameMixin = CreateFromMixins(ResizeLayoutMixin);

function ContentFrameMixin:OnLoad()
    self.texturePool = CreateTexturePool(self, "OVERLAY");
end

function ContentFrameMixin:GeneratePage()
    self.texturePool:ReleaseAll();

    local MIN_TEXTURE_HEIGHT = 20;
    local MAX_TEXTURE_HEIGHT = 40;
    local MIN_TEXTURE_WIDTH = 200;
    local MAX_TEXTURE_WIDTH = 400;

    for i = 1, fastrandom(10, 30) do
        local width = fastrandom(MIN_TEXTURE_WIDTH, MAX_TEXTURE_WIDTH);
        local height = fastrandom(MIN_TEXTURE_HEIGHT, MAX_TEXTURE_HEIGHT);
        local r, g, b = fastrandom(), fastrandom(), fastrandom();

        local texture = self.texturePool:Acquire();
        texture:SetColorTexture(r, g, b);
        texture:SetSize(width, height);
        texture:SetPoint("TOP", 0, -((i - 1) * MAX_TEXTURE_HEIGHT));
        texture:Show();
    end

    -- This is required after you're done laying out your contents; on the
    -- end of the current game tick (OnUpdate) the Layout method provided
    -- by ResizeLayoutMixin will be called which will resize this frame to
    -- the total extents of all child regions.

    self:MarkDirty();
end

---

local ScrollableContentFrameMixin = {};

function ScrollableContentFrameMixin:OnLoad()
    self.ScrollBar = CreateFrame("EventFrame", nil, self, "WowTrimScrollBar");
    self.ScrollBar:SetPoint("TOPRIGHT");
    self.ScrollBar:SetPoint("BOTTOMRIGHT");

    self.ScrollBox = CreateFrame("Frame", nil, self, "WowScrollBox");
    self.ScrollBox:SetPoint("TOPLEFT");
    self.ScrollBox:SetPoint("BOTTOMRIGHT", self.ScrollBar, "BOTTOMLEFT");
    self.ScrollBox:FullUpdate(ScrollBoxConstants.UpdateQueued);

    self.ScrollView = CreateScrollBoxLinearView();
    self.ScrollView:SetPanExtent(50);  -- Controls the distance scrolled.

    -- Note that the content frame must, either directly or indirectly, inherit
    -- ResizeLayoutFrame. It must additionally be parented to the scrollbox
    -- and needs the ".scrollable" field set to true.

    self.ContentFrame = Mixin(CreateFrame("Frame", nil, self.ScrollBox, "ResizeLayoutFrame"), ContentFrameMixin);
    self.ContentFrame.scrollable = true;
    self.ContentFrame:OnLoad();
    self.ContentFrame:SetPoint("TOPLEFT", self.ScrollBox);
    self.ContentFrame:SetPoint("TOPRIGHT", self.ScrollBox);
    self.ContentFrame:SetScript("OnSizeChanged", GenerateClosure(self.OnContentSizeChanged, self));
    self.ContentFrame:GeneratePage();

    -- This generally needs to be called after all scrollable children of the
    -- scrollbox have been created; this will reparent any of its children
    -- with the ".scrollable" field set to that of the inner scroll target
    -- frame.
    --
    -- You can call this _before_ creating all scrollable children, but you'll
    -- need to ensure that instead of being parented to the scrollbox that
    -- they're instead parented to the scroll target - which is accessible from
    -- "self.ScrollBox:GetScrollTarget()".

    ScrollUtil.InitScrollBoxWithScrollBar(self.ScrollBox, self.ScrollBar, self.ScrollView);

    self.GeneratePageButton = CreateFrame("Button", nil, self, "UIPanelButtonTemplate");
    self.GeneratePageButton:SetPoint("TOP", self, "BOTTOM", 0, -20);
    self.GeneratePageButton:SetText("Generate");
    self.GeneratePageButton:SetWidth(150);
    self.GeneratePageButton:SetScript("OnClick", GenerateClosure(self.OnGeneratePageButtonClicked, self));
end

function ScrollableContentFrameMixin:OnContentSizeChanged()
    -- It's expected that OnSizeChanged is only fired when the content layout
    -- frame has recalulated in a deferred manner via OnUpdate, so we can
    -- update the scrollbox immediately without delaying it until the next
    -- game tick.

    self.ScrollBox:FullUpdate(ScrollBoxConstants.UpdateImmediately);
end

function ScrollableContentFrameMixin:OnGeneratePageButtonClicked()
    self:GeneratePage();
end

function ScrollableContentFrameMixin:GeneratePage()
    self.ContentFrame:GeneratePage();
end

---

ScrollableContentFrame = Mixin(CreateFrame("Frame", nil, UIParent), ScrollableContentFrameMixin);
ScrollableContentFrame:SetPoint("CENTER");
ScrollableContentFrame:SetSize(640, 480);
ScrollableContentFrame:OnLoad();