Game development career thread:

using System;
using UnityEngine;
using UnityEngine.UI;
using System.Collections.Generic;


namespace Gumps
{
    internal class Bag
    {
        //parent of all the other parts
        GameObject    mBagFrame;

        PointerListener    mPL;    //track this to unregister event

        Canvas    mCanvas;
        string    mTitle;
        int        mNumSlots;
        int        mBagSlot;    //which slot number is this? (bag slots on character)

        internal event EventHandler    eClosed;


        internal Bag(Canvas canv, string title, int numSlots, int bagSlot)
        {
            mCanvas        =canv;
            mNumSlots    =numSlots;
            mTitle        =title;
            mBagSlot    =bagSlot;

            GameObject    closeButton    =null;
            GameObject    tit            =null;
            foreach(GameObject go in Toolbox.Instance.mUIBits)
            {
                if(go.name == "CloseButton")
                {
                    closeButton    =MakeCloseButton(go);
                }
                else if(go.name == "BagFrame")
                {
                    mBagFrame    =MakeBagFrame(go);
                }
                else if(go.name == "BagSlot")
                {
                    MakeBagSlots(go, mBagFrame);
                }
                else if(go.name == "TitleBar")
                {
                    tit    =MakeBagTitle(go, mBagFrame);
                }
            }

            closeButton.transform.SetParent(mBagFrame.transform, false);

            mPL    =tit.GetComponent<PointerListener>();

            mPL.eDrag    +=OnDrag;
        }


        internal int GetBagSlot()
        {
            return    mBagSlot;
        }


        GameObject    MakeBagTitle(GameObject tit, GameObject parent)
        {
            GameObject    titClone    =GameObject.Instantiate(tit);

            //make a child to hold the text
            GameObject    kid    =new GameObject("TextHolder");

            //find a font for debug
            Font    []fonts    =Resources.FindObjectsOfTypeAll<Font>();
            Font    dbgFont    =fonts[0];

            SetUpTextField(kid, dbgFont);

            Text    tx    =kid.GetComponent<Text>();

            tx.text                        =mTitle;
            tx.rectTransform.position    =Vector3.up;

            kid.transform.SetParent(titClone.transform, false);

            int    w, h;
            CalcSize(out w, out h);

            //set width
            RectTransform    rt    =titClone.GetComponent<RectTransform>();

            int    width    =w * 43 - 20;

            rt.sizeDelta    =new Vector2(width, 30);
            rt.position        =new Vector3(-13, 4);

            titClone.transform.SetParent(parent.transform, false);

            Button    bt    =titClone.GetComponent<Button>();

            return    titClone;
        }


        void MakeBagSlots(GameObject slot, GameObject parent)
        {
            int    w, h;
            CalcSize(out w, out h);

            int    numBoxes    =0;
            for(int y=0;y < h;y++)
            {
                for(int x=0;x < w;x++)
                {
                    GameObject    s    =GameObject.Instantiate(slot);

                    //wire click listener
                    Button    bt    =s.GetComponent<Button>();
                    bt.onClick.AddListener(this.OnClickInventorySlot);

                    int    xCoord    =-4 + (x * -43);
                    int    yCoord    =4 + (y * 43);

                    s.name                    ="Slot" + x + "" + y;
                    s.transform.position    =new Vector3(xCoord, yCoord);

                    s.transform.SetParent(parent.transform, false);

                    numBoxes++;
                    if(numBoxes == mNumSlots)
                    {
                        return;    //done!
                    }
                }
            }
        }


        GameObject MakeBagFrame(GameObject go)
        {
            GameObject    clone    =GameObject.Instantiate(go);

            clone.transform.SetParent(mCanvas.transform, false);

            RectTransform    rt    =clone.GetComponent<RectTransform>();

            int    w, h;
            CalcSize(out w, out h);

            //mul by bag slot size
            w    *=43;
            h    *=43;

            //add border
            w    +=5;
            h    +=30;

            rt.sizeDelta    =new Vector2(w, h);

            return    clone;
        }


        void CalcSize(out int width, out int height)
        {
            //figure out a good number to do the bag dimensions
            //favour a wider base
            width    =Mathf.CeilToInt(Mathf.Sqrt(mNumSlots));

            height    =mNumSlots / width;

            int    remainder    =mNumSlots % width;

            if(remainder > 0)
            {
                height++;
            }
        }


        GameObject MakeCloseButton(GameObject go)
        {
            GameObject    clone    =GameObject.Instantiate(go);

            Button    bt    =clone.GetComponent<Button>();

            bt.onClick.AddListener(this.OnClickClose);

            return    clone;
        }


        Text SetUpTextField(GameObject go, Font font)
        {
            go.AddComponent<Text>();

            Text    tx    =go.GetComponent<Text>();

            tx.color            =Color.magenta;
            tx.raycastTarget    =false;
            tx.alignment        =TextAnchor.MiddleCenter;
            tx.fontSize            =14;
            tx.color            =Color.white;
            tx.fontStyle        =FontStyle.Bold;

            tx.font    =font;

            return    tx;
        }


        void SetUpRectTransform(GameObject go, Vector2 pos, Vector2 sizeDelta)
        {
            //see if already have a recttransform
            RectTransform    rc    =go.GetComponent<RectTransform>();

            if(rc == null)
            {
                //add an empty rect transform
                go.AddComponent<RectTransform>();
            }

            //grab a pointer
            rc    =go.GetComponent<RectTransform>();

            rc.localRotation    =Quaternion.identity;
            rc.localPosition    =new Vector3(pos.x, pos.y);
            rc.localScale        =Vector3.one;
            rc.anchorMin        =Vector2.one * 0.5f;
            rc.anchorMax        =Vector2.one * 0.5f;
            rc.anchoredPosition    =pos;
            rc.sizeDelta        =sizeDelta;
            rc.pivot            =Vector2.one * 0.5f;
        }


        void KeepInRect(RectTransform bigRect, RectTransform smallRect)
        {
            Vector3    smallPos    =smallRect.localPosition;

            Vector3    min    =bigRect.rect.min - smallRect.rect.min;
            Vector3    max    =bigRect.rect.max - smallRect.rect.max;

            smallPos.x    =Mathf.Clamp(smallRect.localPosition.x, min.x, max.x);
            smallPos.y    =Mathf.Clamp(smallRect.localPosition.y, min.y, max.y);

            smallRect.localPosition    =smallPos;
        }


        //adjust the position of the overall gump
        //so that it is all in view
        void ClampFrame()
        {
            //get the frame rect
            RectTransform    bfrt    =mBagFrame.GetComponent<RectTransform>();

            //get the canvas rect
            RectTransform    crt    =mCanvas.GetComponent<RectTransform>();

            KeepInRect(crt, bfrt);
        }


        void OnDrag(object sender, EventArgs ea)
        {
            Vector3    deltaPos    =(Vector3)sender;
            if(deltaPos == null)
            {
                Debug.Log("Null deltaPos in OnDrag()");
            }

            mBagFrame.transform.position    +=deltaPos;

            ClampFrame();
        }


        void OnClickInventorySlot()
        {
            Debug.Log("Inv slot clicked!" + UnityEngine.EventSystems.EventSystem.current.currentSelectedGameObject);
        }


        void OnClickBagTitle()
        {
            Debug.Log("Bag Title Clicked!");
        }


        internal void OnClickClose()
        {
            mPL.eDrag    -=OnDrag;

            GameObject.Destroy(mBagFrame);

            UtilityLib.Misc.SafeInvoke(eClosed, this);
        }
    }
}