NGUI Prefab Toolbar缩略图生成

发表于

NGUI的Prefab Toolbar可以放一些prefab模板，但是在新版Unity上无法显示缩略图，因此写了个工具为选中的NGUI prefab生成缩略图。

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using UnityEditor;
using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System;

public class UISnapshot : MonoBehaviour
{
    public static int screenWidth = (int)NGUITools.screenSize.x;
    public static int screenHeight = (int)NGUITools.screenSize.y;

    /// <summary>
    /// Generate a snapshot for choosed ngui gameobject
    /// </summary>
    [MenuItem("GameObject/Generate Snapshot", priority = 0)]
    public static void GenerateSnapshot()
    {
        //1.摄像机拍整个画面
        //2.截取指定的UI部分
        Debug.Log("Generating snapshot...");
        GameObject go = Selection.activeObject as GameObject;
        if (go == null)
        {
            Debug.Log("Please choose one prefab!");
            return;
        }

        UIRoot uiroot = GameObject.FindObjectOfType<UIRoot>();
        GameObject root = uiroot.gameObject;
        Camera camera = root.transform.Find("Camera").GetComponent<Camera>();
        
        Rect rect = NGUIObjectToRect(go);
        Texture2D t2d = GetTex(camera, rect);
        try
        {
            string path = "Assets/NGUI/Editor/Preview/" + go.name + ".png";
            if (Save2Png(t2d, path))
            {
                UISnapshotPoint sp = go.GetComponent<UISnapshotPoint>();
                if (!sp)
                {
                    sp = go.AddComponent<UISnapshotPoint>();
                }
                sp.thumbnail = t2d;
                Debug.Log("Generating snapshot success!");
            }
        }
        catch (Exception)
        {
            Debug.LogError("Error occured during generating snapshot.");
        }
    }

    //计算NGUI在屏幕中的矩形位置
    private static Rect NGUIObjectToRect(GameObject go)
    {
        Camera camera = NGUITools.FindCameraForLayer(go.layer);
        Bounds bounds = NGUIMath.CalculateAbsoluteWidgetBounds(go.transform);
        Vector3 min = camera.WorldToScreenPoint(bounds.min);
        Vector3 max = camera.WorldToScreenPoint(bounds.max);
        //return new Rect(min.x, min.y, (max.x - min.x), (max.y - min.y));
        //readpixels从左上角开始计算
        return new Rect(min.x, (screenHeight - max.y), (max.x - min.x), (max.y - min.y));
    }

    public static Texture2D GetTex(Camera camera, Rect rect)
    {
        // 创建一个RenderTexture对象
        RenderTexture rt = new RenderTexture(screenWidth, screenHeight, -1);
        camera.targetTexture = rt;
        camera.Render();
        // 激活这个rt 并从中读取像素
        RenderTexture.active = rt;
        Texture2D screenShot = new Texture2D((int)rect.width, (int)rect.height, TextureFormat.RGB24, false);
        // 从RenderTexture.active中读取像素
        screenShot.ReadPixels(rect, 0, 0);
        screenShot.Apply();
        // 重置参数
        camera.targetTexture = null;
        RenderTexture.active = null;
        GameObject.DestroyImmediate(rt);

        return screenShot;
    }

    public static bool Save2Png(Texture2D t2d, string path)
    {
        byte[] bytes = t2d.EncodeToPNG();
        System.IO.File.WriteAllBytes(path, bytes);
        return true;
    }
}

这样就可以点击菜单为prefab生成缩略图了，不过要让NGUI显示出来需要把UISnapshotPointEditor中的OnEnable函数改成以下内容，让NGUI默认使用手动截取的缩略图。

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void OnEnable ()
{
	mType = Type.Manual;
}