So after looking at various examples of handling Pan and Zoom inside of editor windows. I have noted three techniques that can be used to achiever pan and zoom …but not without annoying side-effects or cluttered code in the back end.
Needless to say My code that i spent 2 days working on has its own issues which i would like your help with .
If we can get this working right then it could be helpful to many (i think) .
by now , if you have tried making pan and zoom systems than you have most likely come across
the RectExtension class and its Rect overloads 
we all just use them after briefly reading through the code .
I called it RectExt
it contains extension methods for setting the values of a Rect
download the code and run it in unity . Tools > TestEditor .
if you can help make the zoom happen at the mouse position instead of the uppler left cornner , It would help not just me but everyone who needed a code like this.
[code=CSharp]using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using UnityEditor;
using UnityEngine;
namespace Teststuff
{
public static class RectExt
{
public static Vector2 TopLeft(this Rect rect)
{
return new Vector2(rect.xMin, rect.yMin);
}
public static Rect ScaleSizeBy(this Rect rect, float scale)
{
return rect.ScaleSizeBy(scale, rect.center);
}
public static Rect ScaleSizeBy(this Rect rect, float scale, Vector2 pivotPoint)
{
var result = rect;
result.x -= pivotPoint.x;
result.y -= pivotPoint.y;
result.xMin *= scale;
result.xMax *= scale;
result.yMin *= scale;
result.yMax *= scale;
result.x += pivotPoint.x;
result.y += pivotPoint.y;
return result;
}
public static Rect ScaleSizeBy(this Rect rect, Vector2 scale)
{
return rect.ScaleSizeBy(scale, rect.center);
}
public static Rect ScaleSizeBy(this Rect rect, Vector2 scale, Vector2 pivotPoint)
{
var result = rect;
result.x -= pivotPoint.x;
result.y -= pivotPoint.y;
result.xMin *= scale.x;
result.xMax *= scale.x;
result.yMin *= scale.y;
result.yMax *= scale.y;
result.x += pivotPoint.x;
result.y += pivotPoint.y;
return result;
}
}
//HERE IS THE FUN STUFF
#region PanAndZoom
[Serializable]
public class PanAndZoom
{
#region Variables
private Vector2 Offset = Vector2.zero;
public Vector2 Pan = new Vector2(0, 0);
public float zoom = 1;
private Vector2 PanOffset;
private Matrix4x4 matrix;
private Matrix4x4 normalMatrix = Matrix4x4.TRS(new Vector3(), Quaternion.identity, Vector3.one);
private Vector2 mousePos;
#endregion
#region Begin End Area
public void BeginArea(Rect AreaRect, float min, float max, bool resetPan)
{
GUI.EndGroup();
#region Pan
if (Offset == Vector2.zero && Event.current.rawType == EventType.MouseDown)
Offset = Event.current.mousePosition;
if (Event.current.rawType == EventType.MouseDrag && (Event.current.button == 2 || Event.current.alt))
{
Pan = Event.current.mousePosition - Offset + PanOffset;
Event.current.Use();
}
if (Event.current.rawType == EventType.MouseUp)
{
Offset = Vector2.zero;
PanOffset = Pan;
}
#endregion
#region zoom
if (Event.current.type == EventType.ScrollWheel)
{
if (mousePos != Event.current.mousePosition)
mousePos = Event.current.mousePosition;
Vector2 delta = Event.current.delta;
float zoomDelta = -delta.y / 150.0f;
zoom += zoomDelta * 4;
zoom = Mathf.Clamp(zoom, min, max);
Event.current.Use();
}
var rect = AreaRect.ScaleSizeBy(1f / zoom, AreaRect.TopLeft());
rect.y += 21;
AreaRect = rect;
Matrix4x4 trs = Matrix4x4.TRS(AreaRect.TopLeft(), Quaternion.identity, Vector3.one);
Matrix4x4 scale = Matrix4x4.Scale(new Vector3(zoom, zoom, zoom));
// once we begin zooming out , the pan speed of the content zoomed and the unzoomed canvas (if your canvas size wont change ) will pan slower, so we incleae its pan speed by * (1f / zoom)
GUI.BeginClip(AreaRect, (Pan * (1f / zoom)), Vector2.zero, resetPan);
GUI.matrix = trs * scale * trs.inverse * GUI.matrix;
// this is temporarly used as a reference for the window position and scale
GUI.Box(AreaRect,"I am the size of the window");
#endregion
}
public void EndArea()
{
GUI.matrix = normalMatrix;
GUI.EndClip();
GUI.BeginGroup(new Rect(0f, 21, Screen.width, Screen.height));
}
#endregion
}
#endregion
//USAGE
[Serializable]
public class TestEditor : EditorWindow
{
private PanAndZoom panAndZoom;
[MenuItem("Tools/TestEditor")]
static void Init()
{
EditorWindow shootEditor = GetWindow<TestEditor>();
shootEditor.titleContent.text = "TestEditorr";
}
public void OnEnable()
{
if (panAndZoom == null)
{
panAndZoom = new PanAndZoom();
}
}
public void OnGUI()
{
panAndZoom.BeginArea(new Rect(0, 0, Screen.width, Screen.height), 0.3f, 1, false);
GUI.Box(new Rect(300, 200, 100, 40), " i do nothing");
GUI.Box(new Rect(600, 350, 100, 40), " i do nothing either");
panAndZoom.EndArea();
}
}
}
result
No zoom
With zoom
3137328–237904–TestEditor.cs (5.2 KB)
