Viewport Class

Overview

The Viewport class represents a layout viewport entity in AutoCAD. Viewports are windows in paper space layouts that display views of model space geometry. They allow you to create multiple views of your model at different scales, orientations, and layer visibility settings on a single layout sheet.

Namespace

Autodesk.AutoCAD.DatabaseServices

Inheritance Hierarchy

System.Object
  └─ RXObject
      └─ DBObject
          └─ Entity
              └─ Viewport

Key Properties

Property	Type	Description
`ViewCenter`	`Point2d`	Gets/sets the center point of the view
`ViewTarget`	`Point3d`	Gets/sets the view target point in model space
`ViewDirection`	`Vector3d`	Gets/sets the viewing direction
`ViewHeight`	`double`	Gets/sets the view height in model space units
`CustomScale`	`double`	Gets/sets the custom viewport scale
`StandardScale`	`StandardScaleType`	Gets/sets the standard scale type
`Width`	`double`	Gets/sets the viewport width
`Height`	`double`	Gets/sets the viewport height
`CenterPoint`	`Point3d`	Gets/sets the viewport center in paper space
`On`	`bool`	Gets/sets whether the viewport is active
`Locked`	`bool`	Gets/sets whether the viewport is locked
`NonRectClipEntityId`	`ObjectId`	Gets/sets the non-rectangular clipping boundary

Key Methods

Method	Return Type	Description
`SyncModelView()`	`void`	Synchronizes the viewport with model space view
`GetFrozenLayerList()`	`ObjectIdCollection`	Gets layers frozen in this viewport
`FreezeLayersInViewport(ObjectIdCollection)`	`void`	Freezes layers in this viewport
`ThawLayersInViewport(ObjectIdCollection)`	`void`	Thaws layers in this viewport
`IsLayerFrozenInViewport(ObjectId)`	`bool`	Checks if a layer is frozen in viewport

Code Examples

Example 1: Creating a Simple Viewport

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    // Get a layout (not Model)
    DBDictionary layoutDict = tr.GetObject(db.LayoutDictionaryId, OpenMode.ForRead) as DBDictionary;
    Layout layout = tr.GetObject(layoutDict.GetAt("Layout1"), OpenMode.ForRead) as Layout;
    
    BlockTableRecord layoutBtr = tr.GetObject(layout.BlockTableRecordId, OpenMode.ForWrite) as BlockTableRecord;
    
    // Create viewport
    Viewport viewport = new Viewport();
    viewport.SetDatabaseDefaults();
    
    // Set position and size in paper space
    viewport.CenterPoint = new Point3d(150, 100, 0); // Paper space units (mm)
    viewport.Width = 200;
    viewport.Height = 150;
    
    // Set view properties
    viewport.ViewCenter = new Point2d(0, 0); // Model space center
    viewport.ViewHeight = 100; // Model space height
    
    // Turn on the viewport
    viewport.On = true;
    
    // Add to layout
    layoutBtr.AppendEntity(viewport);
    tr.AddNewlyCreatedDBObject(viewport, true);
    
    tr.Commit();
}

Example 2: Setting Viewport Scale

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    Viewport viewport = tr.GetObject(viewportId, OpenMode.ForWrite) as Viewport;
    
    // Set standard scale (1:50)
    viewport.StandardScale = StandardScaleType.Scale1To50;
    
    // Or set custom scale
    // viewport.CustomScale = 50.0; // 1:50 scale
    
    ed.WriteMessage($"\nViewport scale set to 1:50");
    ed.WriteMessage($"\nView height: {viewport.ViewHeight:F2}");
    
    tr.Commit();
}

Example 3: Freezing Layers in Viewport

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    Viewport viewport = tr.GetObject(viewportId, OpenMode.ForWrite) as Viewport;
    LayerTable lt = tr.GetObject(db.LayerTableId, OpenMode.ForRead) as LayerTable;
    
    // Get layers to freeze
    ObjectIdCollection layersToFreeze = new ObjectIdCollection();
    
    if (lt.Has("Dimensions"))
        layersToFreeze.Add(lt["Dimensions"]);
    if (lt.Has("Text"))
        layersToFreeze.Add(lt["Text"]);
    
    // Freeze layers in this viewport only
    viewport.FreezeLayersInViewport(layersToFreeze);
    
    ed.WriteMessage($"\nFroze {layersToFreeze.Count} layers in viewport");
    
    tr.Commit();
}

Example 4: Reading Viewport Properties

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    Viewport viewport = tr.GetObject(viewportId, OpenMode.ForRead) as Viewport;
    
    ed.WriteMessage("\n=== Viewport Information ===");
    ed.WriteMessage($"\nOn: {viewport.On}");
    ed.WriteMessage($"\nLocked: {viewport.Locked}");
    ed.WriteMessage($"\nCenter Point: {viewport.CenterPoint}");
    ed.WriteMessage($"\nWidth: {viewport.Width:F2}");
    ed.WriteMessage($"\nHeight: {viewport.Height:F2}");
    ed.WriteMessage($"\nView Center: {viewport.ViewCenter}");
    ed.WriteMessage($"\nView Height: {viewport.ViewHeight:F2}");
    ed.WriteMessage($"\nView Target: {viewport.ViewTarget}");
    ed.WriteMessage($"\nView Direction: {viewport.ViewDirection}");
    ed.WriteMessage($"\nCustom Scale: {viewport.CustomScale:F2}");
    ed.WriteMessage($"\nStandard Scale: {viewport.StandardScale}");
    
    // List frozen layers
    ObjectIdCollection frozenLayers = viewport.GetFrozenLayerList();
    ed.WriteMessage($"\n\nFrozen Layers: {frozenLayers.Count}");
    
    foreach (ObjectId layerId in frozenLayers)
    {
        LayerTableRecord ltr = tr.GetObject(layerId, OpenMode.ForRead) as LayerTableRecord;
        ed.WriteMessage($"\n  - {ltr.Name}");
    }
    
    tr.Commit();
}

Example 5: Locking/Unlocking Viewport

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    Viewport viewport = tr.GetObject(viewportId, OpenMode.ForWrite) as Viewport;
    
    // Lock viewport to prevent accidental pan/zoom
    viewport.Locked = true;
    
    ed.WriteMessage($"\nViewport locked: {viewport.Locked}");
    
    tr.Commit();
}

Example 6: Creating Multiple Viewports on Layout

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    DBDictionary layoutDict = tr.GetObject(db.LayoutDictionaryId, OpenMode.ForRead) as DBDictionary;
    Layout layout = tr.GetObject(layoutDict.GetAt("Layout1"), OpenMode.ForRead) as Layout;
    BlockTableRecord layoutBtr = tr.GetObject(layout.BlockTableRecordId, OpenMode.ForWrite) as BlockTableRecord;
    
    // Create 4 viewports in a grid
    double[] scales = { 1.0, 2.0, 4.0, 8.0 };
    string[] scaleNames = { "1:1", "1:2", "1:4", "1:8" };
    
    for (int i = 0; i < 4; i++)
    {
        Viewport vp = new Viewport();
        vp.SetDatabaseDefaults();
        
        // Position in 2x2 grid
        int row = i / 2;
        int col = i % 2;
        vp.CenterPoint = new Point3d(100 + col * 150, 200 - row * 120, 0);
        vp.Width = 120;
        vp.Height = 90;
        
        // Set view
        vp.ViewCenter = new Point2d(0, 0);
        vp.CustomScale = scales[i];
        vp.On = true;
        
        layoutBtr.AppendEntity(vp);
        tr.AddNewlyCreatedDBObject(vp, true);
        
        ed.WriteMessage($"\nCreated viewport {i + 1} at scale {scaleNames[i]}");
    }
    
    tr.Commit();
}

Example 7: Setting Viewport View Direction

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    Viewport viewport = tr.GetObject(viewportId, OpenMode.ForWrite) as Viewport;
    
    // Set isometric view (SW Isometric)
    viewport.ViewDirection = new Vector3d(-1, -1, 1).GetNormal();
    viewport.ViewTarget = Point3d.Origin;
    
    ed.WriteMessage("\nSet viewport to SW Isometric view");
    
    tr.Commit();
}

Example 8: Thawing All Layers in Viewport

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    Viewport viewport = tr.GetObject(viewportId, OpenMode.ForWrite) as Viewport;
    
    // Get all frozen layers
    ObjectIdCollection frozenLayers = viewport.GetFrozenLayerList();
    
    if (frozenLayers.Count > 0)
    {
        // Thaw all layers
        viewport.ThawLayersInViewport(frozenLayers);
        
        ed.WriteMessage($"\nThawed {frozenLayers.Count} layers in viewport");
    }
    else
    {
        ed.WriteMessage("\nNo frozen layers in viewport");
    }
    
    tr.Commit();
}

Standard Scale Types

Common standard scales include:

Scale1To1 - 1:1 (full size)
Scale1To2 - 1:2
Scale1To4 - 1:4
Scale1To5 - 1:5
Scale1To8 - 1:8
Scale1To10 - 1:10
Scale1To16 - 1:16
Scale1To20 - 1:20
Scale1To50 - 1:50
Scale1To100 - 1:100

Viewport States

Property	Description
`On = true`	Viewport displays model space content
`On = false`	Viewport is blank (off)
`Locked = true`	Pan/zoom locked, prevents accidental changes
`Locked = false`	Pan/zoom enabled

Best Practices

Lock Viewports: Lock viewports after setting up to prevent accidental changes
Layer Freezing: Use viewport-specific layer freezing for different views
Standard Scales: Use standard scales for consistency
Viewport Arrangement: Organize viewports logically on layouts
Turn Off When Not Needed: Turn off viewports to improve performance
Named Views: Save named views for complex viewport setups
Visual Styles: Set different visual styles per viewport
Clipping: Use non-rectangular clipping for custom viewport shapes

Common Use Cases

Multi-Scale Drawings: Show overall and detail views
Plan/Elevation/Section: Multiple views of same model
Different Layer Visibility: Show/hide layers per viewport
Isometric Views: 3D isometric alongside plan views
Detail Callouts: Enlarged detail views
Comparison Views: Before/after or design options

Paper Space vs Model Space

Aspect	Paper Space	Model Space
Units	Typically mm or inches	Real-world units
Purpose	Layout and printing	Design and modeling
Viewports	Container for viewports	Viewed through viewports
Scale	1:1 (paper size)	Varies per viewport

Related Objects

Entity - Base class for Viewport
Layout - Paper space layout containing viewports
Database - Contains layout dictionary
LayerTableRecord - Layers that can be frozen per viewport

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Viewport Class

Overview

Namespace

Inheritance Hierarchy

Key Properties

Key Methods

Code Examples

Example 1: Creating a Simple Viewport

Example 2: Setting Viewport Scale

Example 3: Freezing Layers in Viewport

Example 4: Reading Viewport Properties

Example 5: Locking/Unlocking Viewport

Example 6: Creating Multiple Viewports on Layout

Example 7: Setting Viewport View Direction

Example 8: Thawing All Layers in Viewport

Standard Scale Types

Viewport States

Best Practices

Common Use Cases

Paper Space vs Model Space

Related Objects

References

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Viewport Class

Overview

Namespace

Inheritance Hierarchy

Key Properties

Key Methods

Code Examples

Example 1: Creating a Simple Viewport

Example 2: Setting Viewport Scale

Example 3: Freezing Layers in Viewport

Example 4: Reading Viewport Properties

Example 5: Locking/Unlocking Viewport

Example 6: Creating Multiple Viewports on Layout

Example 7: Setting Viewport View Direction

Example 8: Thawing All Layers in Viewport

Standard Scale Types

Viewport States

Best Practices

Common Use Cases

Paper Space vs Model Space

Related Objects

References