UIResizer.cs: Whole-Fat-Pixel UI for NGUI (Unity)

using UnityEngine;

[ExecuteInEditMode, RequireComponent(typeof(UIRoot))]
public class UIResizer : MonoBehaviour {

    public enum GizmoRegion {
        Border,
        Center,
        Edges,
        All,
    };

    public Camera uiCamera;
    public int desiredPixelWidth = 160;
    public int desiredPixelHeight = 120;
    public bool forceUpdate = false;
    public int pixelHeight = 0;
    private int lastPixelWidth = 0;
    private int lastPixelHeight = 0;
    private int lastManualHeight = 0;
    private float desiredScreenRatio;

    public GizmoRegion gizmoRegion = GizmoRegion.Border;

    void OnEnable() {
        if(uiCamera == null) {
            uiCamera = GetComponentInChildren<Camera>();
        }
    }

    void Update() {
        if(desiredPixelWidth <= 0) {
            desiredPixelWidth = 1;
        }
        if(desiredPixelHeight <= 0) {
            desiredPixelHeight = 1;
        }

        UIRoot root = GetComponent<UIRoot>();
        if(desiredPixelWidth != lastPixelWidth ||
            desiredPixelHeight != lastPixelHeight ||
            lastManualHeight != root.manualHeight ||
            forceUpdate) {
            forceUpdate = false;
            lastPixelWidth = desiredPixelWidth;
            lastPixelHeight = desiredPixelHeight;
            lastManualHeight = root.manualHeight;

            desiredScreenRatio = (float)desiredPixelWidth / (float)desiredPixelHeight;

            // Find the largest scale that fits in the height.
            int pixelScale = 1;
            while(desiredPixelWidth * (pixelScale + 1) <= Screen.width &&
                desiredPixelHeight * (pixelScale + 1) <= Screen.height) {
                pixelScale++;
            }

            // Set the UIRoot's manual scale to that!
            root.minimumHeight = 1;
            root.maximumHeight = 4096;
            root.manualHeight = Screen.height / pixelScale;
            root.automatic = false;
            lastManualHeight = root.manualHeight;

            root.SendMessage("Update");
            pixelHeight = pixelScale;
        }
    }

#if UNITY_EDITOR
    void OnDrawGizmos() {
        float aspectRatio = uiCamera.aspect;

        float screenTop = transform.localScale.y * lastManualHeight / 2;
        float screenBottom = -transform.localScale.y * lastManualHeight / 2;
        float screenLeft = -transform.localScale.x * lastManualHeight / 2 * aspectRatio;
        float screenRight = transform.localScale.x * lastManualHeight / 2 * aspectRatio;

        float minAspectTop = transform.localScale.y * desiredPixelHeight / 2;
        float minAspectBottom = -transform.localScale.y * desiredPixelHeight / 2;
        float minAspectLeft = -transform.localScale.x * desiredPixelHeight / 2 * desiredScreenRatio;
        float minAspectRight = transform.localScale.x * desiredPixelHeight / 2 * desiredScreenRatio;

        // Center cross.
        Gizmos.color = new Color(1f, 1f, 1f, 0.2f);
        Gizmos.DrawLine(new Vector3(0f, screenTop, 0f) + transform.localPosition, new Vector3(0f, screenBottom, 0f) + transform.localPosition);
        Gizmos.DrawLine(new Vector3(screenLeft, 0f, 0f) + transform.localPosition, new Vector3(screenRight, 0f, 0f) + transform.localPosition);

        // Screen outline.
        Gizmos.color = new Color(1f, 1f, 1f, 0.6f);
        Gizmos.DrawWireCube(transform.localPosition, new Vector3(screenRight - screenLeft, screenTop - screenBottom, 0f));

        if(gizmoRegion == GizmoRegion.Center || gizmoRegion == GizmoRegion.All) {
            float edgeSize;
            float edgeCenter;

            // Left and right danger zones.
            Gizmos.color = new Color(1f, 0f, 0f, 0.2f);
            edgeSize = minAspectLeft - screenLeft;
            if(edgeSize < 0f) {
                Gizmos.color = new Color(0f, 0.5f, 0f, 0.2f);
                edgeSize = Mathf.Abs(edgeSize);
            }
            edgeCenter = (minAspectLeft + screenLeft) / 2;
            Gizmos.DrawCube(new Vector3(edgeCenter, 0f, 0f) + transform.localPosition, new Vector3(edgeSize, screenTop - screenBottom, 0f));
            edgeCenter = (minAspectRight + screenRight) / 2;
            Gizmos.DrawCube(new Vector3(edgeCenter, 0f, 0f) + transform.localPosition, new Vector3(edgeSize, screenTop - screenBottom, 0f));

            // Top and bottom danger zones.
            Gizmos.color = new Color(1f, 0f, 0f, 0.2f);
            edgeSize = screenTop - minAspectTop;
            if(edgeSize < 0f) {
                Gizmos.color = new Color(0f, 0.5f, 0f, 0.2f);
                edgeSize = Mathf.Abs(edgeSize);
            }
            edgeCenter = (minAspectTop + screenTop) / 2;
            Gizmos.DrawCube(new Vector3(0f, edgeCenter, 0f) + transform.localPosition, new Vector3(screenRight - screenLeft, edgeSize, 0f));
            edgeCenter = (minAspectBottom + screenBottom) / 2;
            Gizmos.DrawCube(new Vector3(0f, edgeCenter, 0f) + transform.localPosition, new Vector3(screenRight - screenLeft, edgeSize, 0f));

            Gizmos.color = new Color(1f, 0f, 0f, 0.8f);
            Gizmos.DrawWireCube(transform.localPosition, new Vector3(minAspectRight - minAspectLeft, minAspectTop - minAspectBottom, 0f));
        }
        if(gizmoRegion == GizmoRegion.Edges || gizmoRegion == GizmoRegion.All) {
            float edgeSize;
            //float edgeCenter;

            // Left and right safe zones.
            Gizmos.color = new Color(0f, 1f, 1f, 0.8f);
            edgeSize = -minAspectLeft;
            if(minAspectLeft < screenLeft) {
                Gizmos.color = new Color(1f, 1f, 0f, 0.8f);
            }
            /*edgeCenter = screenLeft - minAspectLeft / 2;
            Gizmos.DrawCube(new Vector3(edgeCenter, 0f, 0f), new Vector3(edgeSize, screenTop - screenBottom, 0f));
            edgeCenter = screenRight - minAspectRight / 2;
            Gizmos.DrawCube(new Vector3(edgeCenter, 0f, 0f), new Vector3(edgeSize, screenTop - screenBottom, 0f));*/
            Gizmos.DrawLine(new Vector3(screenLeft + edgeSize, screenTop, 0f) + transform.localPosition,
                new Vector3(screenLeft + edgeSize, screenBottom, 0f) + transform.localPosition);
            Gizmos.DrawLine(new Vector3(screenRight - edgeSize, screenTop, 0f) + transform.localPosition,
                new Vector3(screenRight - edgeSize, screenBottom, 0f) + transform.localPosition);

            // Top and bottom safe zones.
            Gizmos.color = new Color(0f, 1f, 1f, 0.8f);
            edgeSize = minAspectTop;
            if(screenTop < minAspectTop) {
                Gizmos.color = new Color(1f, 1f, 0f, 0.8f);
            }
            /*edgeCenter = screenTop - minAspectTop / 2;
            Gizmos.DrawCube(new Vector3(0f, edgeCenter, 0f), new Vector3(screenRight - screenLeft, edgeSize, 0f));
            edgeCenter = screenBottom - minAspectBottom / 2;
            Gizmos.DrawCube(new Vector3(0f, edgeCenter, 0f), new Vector3(screenRight - screenLeft, edgeSize, 0f));*/
            Gizmos.DrawLine(new Vector3(screenLeft, screenTop - edgeSize, 0f) + transform.localPosition,
                new Vector3(screenRight, screenTop - edgeSize, 0f) + transform.localPosition);
            Gizmos.DrawLine(new Vector3(screenLeft, screenBottom + edgeSize, 0f) + transform.localPosition,
                new Vector3(screenRight, screenBottom + edgeSize, 0f) + transform.localPosition);
        }
    }
#endif
}