Click Callbacks

When a player with input capture clicks a button in a layout, the client sends a CCSUsrMsg_CustomHudClicked user message carrying the layout entity and the clicked panel's id. The core catches it and calls the callbacks registered on that layout entity.

HookClick

void CCSCustomHudLayout::HookClick(std::function<void(CCSPlayerController*, CCSCustomHudLayout*, const char*)> callback);
void CCSCustomHudLayout::UnhookClicks();

The callback gets the player who clicked, the layout, and the id attribute of the clicked panel:

<root>
    <styles>
        <include src="s2r://panorama/styles/custom_game/my_menu.vcss_c" />
    </styles>
    <Panel class="screen">
        <Panel id="MenuRoot" class="menu">
            <Button id="buy_ak47" class="row"><Label text="AK-47" /></Button>
            <Button id="buy_m4a1" class="row"><Label text="M4A1" /></Button>
            <Button id="close" class="close"><Label text="X" /></Button>
        </Panel>
    </Panel>
</root>

CHandle<CCSCustomHudLayout> g_hMenu;

void CreateMenu()
{
    CCSCustomHudLayout* pMenu = CCSCustomHudLayout::Create("my_menu");
    if (!pMenu)
        return;

    pMenu->HookClick([](CCSPlayerController* pPlayer, CCSCustomHudLayout* pLayout, const char* pszButtonId)
    {
        if (!V_strcmp(pszButtonId, "close"))
        {
            pLayout->SetHasClass("MenuRoot", "show", false, pPlayer);
            pLayout->SetInputCaptureEnabled(false, pPlayer);
            return;
        }

        CCSPlayerPawn* pPawn = pPlayer->GetPlayerPawn();
        if (!pPawn || !pPlayer->m_bPawnIsAlive())
            return;

        CPlayer_ItemServices* pItems = pPawn->m_pItemServices();
        if (!pItems)
            return;

        if (!V_strcmp(pszButtonId, "buy_ak47"))
            pItems->GiveNamedItem("weapon_ak47");
        else if (!V_strcmp(pszButtonId, "buy_m4a1"))
            pItems->GiveNamedItem("weapon_m4a1");
    });

    g_hMenu = pMenu->GetHandle();
}

Things to keep in mind:

• The id is the only thing that identifies a button. It comes from the client, so treat it as input: compare it against the ids you know, and check that this player is allowed to do what the button does right now — do not assume only players you showed the menu to can click it.
• Every player's clicks arrive at the same callback. Per-player menus (different pages for different players) are told apart by your own state keyed by the player, not by the layout.
• UnhookClicks() drops every callback on the layout, including ones other code registered on it. Several HookClick calls on one layout all fire, in the order they were added.
• A callback may create another layout or unhook itself; the core collects the matching callbacks before calling any of them.

Lifetime

You rarely need to unhook:

• A callback is dropped when its layout entity is removed — the entity is stored as a handle, and dead entries are pruned the next time a click comes in.
• All of a plugin's callbacks are dropped when that plugin unloads.
• The whole registry is cleared on level shutdown, along with the entities.

A removed layout's index being reused by a new entity cannot trigger an old callback: the match is made on the full handle, serial number included.

ISource2ModCustomHud

HookClick and UnhookClicks forward to ISource2ModCustomHud, the registry of callbacks the core owns. You can call it directly; the macros only fill in g_pSource2ModCustomHud:

#include "source2mod/ISource2ModCustomHud.h"

using CustomHudClickHandler = Source2ModCallback<void(CCSPlayerController* player, CCSCustomHudLayout* pLayout, const char* pszButtonId)>;

virtual Source2ModHookId HookCustomHudClick(CCSCustomHudLayout* pLayout, CustomHudClickHandler handler) = 0;
virtual bool UnhookCustomHudClick(CCSCustomHudLayout* pLayout, const CustomHudClickHandler& handler) = 0;
virtual bool UnhookCustomHudClick(Source2ModHookId id) = 0;
virtual void UnhookCustomHudClick(CCSCustomHudLayout* pLayout) = 0;

HOOK_CUSTOM_HUD_CLICK(pLayout, handler);   // g_pSource2ModCustomHud->HookCustomHudClick(pLayout, handler)
UNHOOK_CUSTOM_HUD_CLICK(pLayout);          // g_pSource2ModCustomHud->UnhookCustomHudClick(pLayout)

There is no plugin id argument: the handler is a lambda, a function or an object and a method (SOURCE2MOD_MEMBER(this, &MyPlugin::OnMenuClick)), and the core reads which plugin it belongs to off the handler. HookCustomHudClick returns a Source2ModHookId; UnhookCustomHudClick(id) drops that one callback, UnhookCustomHudClick(pLayout, handler) drops a function or object-and-method callback passed again (a lambda only goes by id), and UnhookCustomHudClick(pLayout) drops every callback on the layout.

It exists as an interface because the click arrives on the core's own hook (ClientSvcUserMessage) and has to be routed back to whichever plugin created the layout. A null layout or an empty handler is ignored.

When clicks do not arrive

A layout that renders but never calls back is almost always one of:

1. Input capture is off for that player — no cursor, no clicks.
2. The clicked element has no id, or the id in the layout differs from the one your callback compares against.
3. The callback is on a different entity — for example one created before a map change, whose handle is now dead.