Is there a better way to create a color picker in Unity C# and NGUI?

Question

I am creating a bit of an art program / game in Unity, however I need to create a color picker for the artists who are building things inside it. I am using the NGUI UI system, and I've created a basic sprite with a set of colors on it, along with a custom color input.

However, actually selecting one of those colors accurately is not proving easy. I'm currently doing it like this:

IEnumerator CaptureTempArea()
{
    yield return new WaitForEndOfFrame();

    tex = new Texture2D(Screen.width, Screen.height);
    tex.ReadPixels(new Rect(0, 0, Screen.width, Screen.height), 0, 0);
    tex.Apply();


    Vector2 pos = UICamera.lastEventPosition;

    int x = (int)pos.x;

    int y = (int)pos.y;

    Color color = tex.GetPixel(x, y);

    Debug.Log(ColorToHex(color));

    Debug.Log(tex.GetRawTextureData().Length / 1000);

    Destroy(tex);
    tex = null;
}

However, there must be a better way to capture -just- the specific area. This does accurately get the colors, however. But it also generates an image - even temporary - that is anywhere from 2 to 8 MB in size before it gets cleared from the buffer. Given the specific UI system, is there a better way to create a color picker, or one that will use less memory?

Answer 1

in general, I would optimize some stuff, like avoiding allocating/reading the while texture just to obtain a single pixel, and keeping a live 1x1 texture throughout the entire session... if your device support it you can also use computebuffer to pass the color value from a shader... this is how your code should look like (I haven't tested it, just rewritten your code a bit)

Texture2D tex;

void Start() {
    tex = new Texture2D(1, 1);
    //get the color printed by calling:
    StartCoroutine(CaptureTempArea());
}

IEnumerator CaptureTempArea() {
    yield return new WaitForEndOfFrame();
    Vector2 pos = UICamera.lastEventPosition;
    tex.ReadPixels(new Rect(pos.x, pos.y, 1, 1), 0, 0);
    tex.Apply();
    Color color = tex.GetPixel(0, 0);
    Debug.Log(ColorToHex(color));
}

void OnDestroy() {
    Destroy(tex);
}