diff --git a/Document-Processing-toc.html b/Document-Processing-toc.html
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Sticky Notes Annotation
Measurement Annotation
Free Text Annotation
+ Line angle Constraints
Ink Annotation
Import and Export Annotations
Comments
@@ -639,6 +640,7 @@
Measurement Annotation
Free Text Annotation
Ink Annotation
+ Line angle Constraints
Comments
Handwritten signature
@@ -765,6 +767,7 @@
Measurement Annotation
Free Text Annotation
Ink Annotation
+ Line angle Constraints
Comments
diff --git a/Document-Processing/PDF/PDF-Viewer/angular/annotation/line-angle-constraints.md b/Document-Processing/PDF/PDF-Viewer/angular/annotation/line-angle-constraints.md
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+---
+layout: post
+title: Line Angle Constraints in Angular PDF Viewer | Syncfusion
+description: Learn all about Line Angle Constraints Annotation in the Syncfusion Angular PDF Viewer component of Essential JS 2 and more.
+platform: document-processing
+control: Line Angle Constraints
+documentation: ug
+---
+
+# Line Angle Constraints in Angular PDF Viewer
+
+The PDF Viewer control provides robust **line angle constraints** functionality. This allows users to draw line type annotations with controlled angle snapping, improving accuracy and consistency across technical drawings and measurements across your PDF documents.
+
+## Enabling Line Angle Constraints
+To enable line angle constraints, configure the `enableLineAngleConstraints` property within the `annotationDrawingOptions` of the PDF Viewer. When enabled, line-type annotations are automatically restricted to fixed angles.
+
+The following code demonstrates how to enable line angle constraints:
+
+```html
+
+
+```
+
+```typescript
+import { Component, ViewEncapsulation, OnInit,ViewChild} from '@angular/core';
+import { PdfViewerComponent, LinkAnnotationService, BookmarkViewService, MagnificationService, ThumbnailViewService, ToolbarService, NavigationService, TextSearchService, TextSelectionService, PrintService, AnnotationService, FormFieldsService, FormDesignerService, PageOrganizerService,PdfViewerModule, TextSelectionStartEventArgs, AnnotationSelectEventArgs } from '@syncfusion/ej2-angular-pdfviewer';
+import { SwitchComponent, SwitchModule } from '@syncfusion/ej2-angular-buttons';
+import { ClickEventArgs } from '@syncfusion/ej2-buttons';
+
+
+/**
+* Default PdfViewer Controller
+*/
+@Component({
+ selector: 'app-root',
+ templateUrl: 'app.component.html',
+ encapsulation: ViewEncapsulation.None,
+ // tslint:disable-next-line:max-line-length
+ providers: [LinkAnnotationService, BookmarkViewService, MagnificationService, ThumbnailViewService, ToolbarService, NavigationService,
+ TextSearchService, TextSelectionService, PrintService, AnnotationService, FormFieldsService, FormDesignerService,PageOrganizerService],
+ styleUrls: ['app.component.css'],
+ standalone: true,
+ imports: [
+
+ SwitchModule,
+ PdfViewerModule,
+
+ ],
+})
+
+export class AppComponent {
+ @ViewChild('pdfviewer')
+ public pdfviewerControl: PdfViewerComponent | undefined;
+
+ public document: string = 'https://cdn.syncfusion.com/content/pdf/pdf-succinctly.pdf';
+ public resource:string = "https://cdn.syncfusion.com/ej2/31.1.17/dist/ej2-pdfviewer-lib";
+ public annotationDrawingOptions = {
+ enableLineAngleConstraints: true,
+ restrictLineAngleTo: 90
+ };
+ ngOnInit(): void {
+ // ngOnInit function
+ }
+}
+```
+
+## Configuration Properties
+
+### enableLineAngleConstraints
+
+The `enableLineAngleConstraints` property activates angle snapping for line-based annotations. When set to `true`, the following annotation types will snap to fixed angles as defined by the `restrictLineAngleTo` property:
+
+- Lines
+- Arrows
+- Polygon
+- Distance measurements
+- Perimeter measurements
+- Area measurements
+- Volume measurements
+
+**Key Benefits:**
+
+- Automatic angle snapping during the drawing
+- Enhanced precision for technical drawings and measurements
+- Desktop support: Hold **Shift** while drawing to activate constraints
+- Real-time visual feedback showing angle snapping behavior
+
+### restrictLineAngleTo
+
+The `restrictLineAngleTo` property defines the angle increment (in degrees) that constrains line-based annotations. The default value is **45 degrees**.
+
+**Angle Snapping Rules:**
+
+- The initial drawing direction is treated as the 0° reference point
+- Snapped angles are calculated based on the increment
+- If the increment doesn’t divide 360 evenly, angles reset after 360°
+
+**Examples:**
+
+- restrictLineAngleTo: 45 → Snapped angles: 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°, 360°
+- restrictLineAngleTo: 100 → Snapped angles: 0°, 100°, 200°, 300°, 360°
+
+## Working with Constrained Annotations
+
+### Drawing Behavior
+
+When line angle constraints are enabled:
+
+**Initial Drawing:** Start drawing a line, arrow, polygon, distance, perimeter, area, or volume as usual.
+**Angle Snapping:** The line snaps to the nearest allowed angle.
+**Visual Feedback:** Snapped angle is shown in real time.
+**Completion:** Release to complete the annotation.
+
+### Keyboard Shortcuts
+
+**Desktop Platforms:**
+
+**Shift + Drag:** Enables angle snapping even when `enableLineAngleConstraints` is false.
+
+### Selector-Based Modifications
+
+When modifying existing line annotations using selectors:
+
+- Constraints apply based on the original line direction.
+- The reference angle (0°) is determined by the lines current orientation.
+- Only lines and arrows support constraint snapping during modification.
+- Adjustments snap to the configured angle increment relative to the original direction.
+
+N> You can refer to our [Angular PDF Viewer](https://www.syncfusion.com/angular-ui-components/angular-pdf-viewer) feature tour page for its groundbreaking feature representations. You can also explore our [Angular PDF Viewer example](https://github.com/syncfusion/ej2-angular-samples/tree/master/src/app/pdfviewer) to know how to render and configure the PDF Viewer.
diff --git a/Document-Processing/PDF/PDF-Viewer/react/annotation/line-angle-constraints.md b/Document-Processing/PDF/PDF-Viewer/react/annotation/line-angle-constraints.md
new file mode 100644
index 000000000..17904cc77
--- /dev/null
+++ b/Document-Processing/PDF/PDF-Viewer/react/annotation/line-angle-constraints.md
@@ -0,0 +1,115 @@
+---
+layout: post
+title: Line Angle Constraints in React PDF Viewer | Syncfusion
+description: Learn all about Line Angle Constraints Annotation in the Syncfusion React PDF Viewer component of Essential JS 2 and more.
+platform: document-processing
+control: Line Angle Constraints
+documentation: ug
+---
+
+# Line Angle Constraints in React PDF Viewer
+
+The PDF Viewer control provides robust **line angle constraints** functionality. This allows users to draw line type annotations with controlled angle snapping, improving accuracy and consistency across technical drawings and measurements across your PDF documents.
+
+## Enabling Line Angle Constraints
+To enable line angle constraints, configure the `enableLineAngleConstraints` property within the `annotationDrawingOptions` of the PDF Viewer. When enabled, line-type annotations are automatically restricted to fixed angles.
+
+The following code demonstrates how to enable line angle constraints:
+
+{% tabs %}
+{% highlight js tabtitle="Standalone" %}
+{% raw %}
+
+import * as ReactDOM from 'react-dom';
+import * as React from 'react';
+import './index.css';
+import { PdfViewerComponent, Toolbar, Magnification, Navigation, LinkAnnotation, BookmarkView, ThumbnailView, Print, TextSelection, Annotation, TextSearch, FormFields, FormDesigner, Inject } from '@syncfusion/ej2-react-pdfviewer';
+export function App() {
+ return ();
+}
+const root = ReactDOM.createRoot(document.getElementById('sample'));
+root.render();
+
+{% endraw %}
+{% endhighlight %}
+
+## Configuration Properties
+
+### enableLineAngleConstraints
+
+The `enableLineAngleConstraints` property activates angle snapping for line-based annotations. When set to `true`, the following annotation types will snap to fixed angles as defined by the `restrictLineAngleTo` property:
+
+- Lines
+- Arrows
+- Polygon
+- Distance measurements
+- Perimeter measurements
+- Area measurements
+- Volume measurements
+
+**Key Benefits:**
+
+- Automatic angle snapping during the drawing
+- Enhanced precision for technical drawings and measurements
+- Desktop support: Hold **Shift** while drawing to activate constraints
+- Real-time visual feedback showing angle snapping behavior
+
+### restrictLineAngleTo
+
+The `restrictLineAngleTo` property defines the angle increment (in degrees) that constrains line-based annotations. The default value is **45 degrees**.
+
+**Angle Snapping Rules:**
+
+- The initial drawing direction is treated as the 0° reference point
+- Snapped angles are calculated based on the increment
+- If the increment doesn’t divide 360 evenly, angles reset after 360°
+
+**Examples:**
+
+- restrictLineAngleTo: 45 → Snapped angles: 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°, 360°
+- restrictLineAngleTo: 100 → Snapped angles: 0°, 100°, 200°, 300°, 360°
+
+## Working with Constrained Annotations
+
+### Drawing Behavior
+
+When line angle constraints are enabled:
+
+**Initial Drawing:** Start drawing a line, arrow, polygon, distance, perimeter, area, or volume as usual.
+**Angle Snapping:** The line snaps to the nearest allowed angle.
+**Visual Feedback:** Snapped angle is shown in real time.
+**Completion:** Release to complete the annotation.
+
+### Keyboard Shortcuts
+
+**Desktop Platforms:**
+
+**Shift + Drag:** Enables angle snapping even when `enableLineAngleConstraints` is false.
+
+### Selector-Based Modifications
+
+When modifying existing line annotations using selectors:
+
+- Constraints apply based on the original line direction.
+- The reference angle (0°) is determined by the lines current orientation.
+- Only lines and arrows support constraint snapping during modification.
+- Adjustments snap to the configured angle increment relative to the original direction.
+
+N> You can refer to our [React PDF Viewer](https://www.syncfusion.com/React-ui-components/React-pdf-viewer) feature tour page for its groundbreaking feature representations. You can also explore our [React PDF Viewer example](https://github.com/syncfusion/ej2-React-samples/tree/master/src/app/pdfviewer) to know how to render and configure the PDF Viewer.
diff --git a/Document-Processing/PDF/PDF-Viewer/vue/annotation/line-angle-constraints.md b/Document-Processing/PDF/PDF-Viewer/vue/annotation/line-angle-constraints.md
new file mode 100644
index 000000000..97f1c2b7f
--- /dev/null
+++ b/Document-Processing/PDF/PDF-Viewer/vue/annotation/line-angle-constraints.md
@@ -0,0 +1,142 @@
+---
+layout: post
+title: Line Angle Constraints in Vue PDF Viewer | Syncfusion
+description: Learn all about Line Angle Constraints Annotation in the Syncfusion Vue PDF Viewer component of Essential JS 2 and more.
+platform: document-processing
+control: Line Angle Constraints
+documentation: ug
+---
+
+# Line Angle Constraints in Vue PDF Viewer
+
+The PDF Viewer control provides robust **line angle constraints** functionality. This allows users to draw line type annotations with controlled angle snapping, improving accuracy and consistency across technical drawings and measurements across your PDF documents.
+
+## Enabling Line Angle Constraints
+To enable line angle constraints, configure the `enableLineAngleConstraints` property within the `annotationDrawingOptions` of the PDF Viewer. When enabled, line-type annotations are automatically restricted to fixed angles.
+
+The following code demonstrates how to enable line angle constraints:
+
+{% tabs %}
+{% highlight html tabtitle="Composition API (Standalone)" %}
+
+
+
+
+
+
+
+
+
+
+{% endhighlight %}
+{% highlight html tabtitle="Options API (Standalone)" %}
+
+## Configuration Properties
+
+### enableLineAngleConstraints
+
+The `enableLineAngleConstraints` property activates angle snapping for line-based annotations. When set to `true`, the following annotation types will snap to fixed angles as defined by the `restrictLineAngleTo` property:
+
+- Lines
+- Arrows
+- Polygon
+- Distance measurements
+- Perimeter measurements
+- Area measurements
+- Volume measurements
+
+**Key Benefits:**
+
+- Automatic angle snapping during the drawing
+- Enhanced precision for technical drawings and measurements
+- Desktop support: Hold **Shift** while drawing to activate constraints
+- Real-time visual feedback showing angle snapping behavior
+
+### restrictLineAngleTo
+
+The `restrictLineAngleTo` property defines the angle increment (in degrees) that constrains line-based annotations. The default value is **45 degrees**.
+
+**Angle Snapping Rules:**
+
+- The initial drawing direction is treated as the 0° reference point
+- Snapped angles are calculated based on the increment
+- If the increment doesn’t divide 360 evenly, angles reset after 360°
+
+**Examples:**
+
+- restrictLineAngleTo: 45 → Snapped angles: 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°, 360°
+- restrictLineAngleTo: 100 → Snapped angles: 0°, 100°, 200°, 300°, 360°
+
+## Working with Constrained Annotations
+
+### Drawing Behavior
+
+When line angle constraints are enabled:
+
+**Initial Drawing:** Start drawing a line, arrow, polygon, distance, perimeter, area, or volume as usual.
+**Angle Snapping:** The line snaps to the nearest allowed angle.
+**Visual Feedback:** Snapped angle is shown in real time.
+**Completion:** Release to complete the annotation.
+
+### Keyboard Shortcuts
+
+**Desktop Platforms:**
+
+**Shift + Drag:** Enables angle snapping even when `enableLineAngleConstraints` is false.
+
+### Selector-Based Modifications
+
+When modifying existing line annotations using selectors:
+
+- Constraints apply based on the original line direction.
+- The reference angle (0°) is determined by the lines current orientation.
+- Only lines and arrows support constraint snapping during modification.
+- Adjustments snap to the configured angle increment relative to the original direction.
+
+N> You can refer to our [Vue PDF Viewer](https://www.syncfusion.com/vue-ui-components/vue-pdf-viewer) feature tour page for its groundbreaking feature representations. You can also explore our [Vue PDF Viewer example](https://github.com/syncfusion/ej2-Vue-samples/tree/master/src/app/pdfviewer) to know how to render and configure the PDF Viewer.