Place things

place_things.lua

--Made by a completely reasonable person for 100% legitimate reasons. 
obs = obslua

screen = ""
webcam = ""

-- A very useful debug method
function log(message)
    obs.script_log(obs.LOG_INFO, message)
end

function script_update(settings)
    screen = obs.obs_data_get_string(settings, "screen")
    webcam = obs.obs_data_get_string(settings, "webcam")
end

function script_properties()
    local props = obs.obs_properties_create()
    local p = obs.obs_properties_add_list(props, "screen", "Full screen capture", obs.OBS_COMBO_TYPE_EDITABLE, obs.OBS_COMBO_FORMAT_STRING)
    local q = obs.obs_properties_add_list(props, "webcam", "Webcam", obs.OBS_COMBO_TYPE_EDITABLE, obs.OBS_COMBO_FORMAT_STRING)

    local sources = obs.obs_enum_sources()
    if sources ~= nil then
        for _, source in ipairs(sources) do
            local source_id = obs.obs_source_get_id(source)
            
            -- Win name or Mac name
            if (source_id == "monitor_capture") or (source_id == "display_capture") or (source_if == 'window_capture') then
                local name = obs.obs_source_get_name(source)
                obs.obs_property_list_add_string(p, name, name)
            end

            -- Win name or Mac name
            if (source_id == "dshow_input") or (source_id == "av_capture_input") then
                local name = obs.obs_source_get_name(source)
                obs.obs_property_list_add_string(q, name, name)
            end
        end
    end
    obs.source_list_release(sources)

    obs.obs_properties_add_button(props, "my_button", "Place things", place_things_just_right)

    return props
end

function place_things_just_right()
    local source = obs.obs_get_source_by_name(screen)
    if source ~= nil then
        --Place the full screen image
        local video_info = obs.obs_video_info()
        obs.obs_get_video_info(video_info)

        local the_scene_item = find_scene_item_from_source(source)
        if the_scene_item ~= nil then

            local scale = obs.vec2()
            local w = obs.obs_source_get_width(source)
            local h = obs.obs_source_get_height(source)
            local mult = video_info.base_width / w
            
            scale.x = mult
            scale.y = mult
            obs.obs_sceneitem_set_scale(the_scene_item, scale)

            local pos = obs.vec2()
            pos.x = 0
            pos.y = 0
            obs.obs_sceneitem_set_pos(the_scene_item, pos)
            
            local dy = h - video_info.base_height / scale.y

            if dy >= 0 then
                crp = obs.obs_sceneitem_crop()
                crp.top = math.floor(dy / 2.0)
                -- Leave it out because it doesn't really matter
                --crp.bottom = math.floor(dy / 2.0)
                crp.left = 0
                crp.right = 0
                obs.obs_sceneitem_set_crop(the_scene_item, crp)
            end
        end
    end

    local source = obs.obs_get_source_by_name(webcam)
    if source ~= nil then
        local video_info = obs.obs_video_info()
        obs.obs_get_video_info(video_info)

        local the_scene_item = find_scene_item_from_source(source)

        if the_scene_item ~= nil then

            local w = obs.obs_source_get_width(source)
            local h = obs.obs_source_get_height(source)

            local target_w = 381 * video_info.base_width / 1920
            local target_h = 253 * video_info.base_height / 1080

            local aspect_ratio = w / h

            local scale = 1
            if aspect_ratio > target_w / target_h then
                -- Crop from the left and right
                scale = target_h / h
                local to_crop = (w - h * target_w / target_h) / 2

                crp = obs.obs_sceneitem_crop()
                crp.left = math.floor(to_crop)
                crp.right = math.floor(to_crop)

                crp.top = 0
                crp.bottom = 0
                obs.obs_sceneitem_set_crop(the_scene_item, crp)
            end

            if aspect_ratio < target_w / target_h then
                -- Crop from the top and bottom
                scale = target_w / w
                local to_crop = (h - w * target_h / target_w) / 2

                crp = obs.obs_sceneitem_crop()
                crp.bottom = math.floor(to_crop)
                crp.top = math.floor(to_crop)
                obs.obs_sceneitem_set_crop(the_scene_item, crp)
            end

            local total_scale = obs.vec2()
            total_scale.x = scale
            total_scale.y = scale

            obs.obs_sceneitem_set_scale(the_scene_item, total_scale)

            local pos = obs.vec2()
            pos.x = video_info.base_width - target_w
            pos.y = 0
            obs.obs_sceneitem_set_pos(the_scene_item, pos)
        end
    end
end

-- OBS has a roundabout way of going through the scene, but as long as there are no
-- duplicate names this should work.
function find_scene_item_from_source(source)
    local current_scene_source = obs.obs_frontend_get_current_scene()
    local current_scene = obs.obs_scene_from_source(current_scene_source)
    local scene_items = obs.obs_scene_enum_items(current_scene)
    
    local the_scene_item = nil
    local source_name = obs.obs_source_get_name(source)

    for i, scene_item in ipairs(scene_items) do
        if obs.obs_source_get_name(obs.obs_sceneitem_get_source(scene_item)) == source_name then
            the_scene_item = scene_item
        end
    end

    obs.sceneitem_list_release(scene_items)
    return the_scene_item
end