How to: Custom Draw in the PDF Viewer

• Nov 13, 2018
• 3 minutes to read

The PDF Viewer can draw graphics in the PDF document in the Control.Paint event handler.

In this example, the filled rectangle is drawn at any document space when you hold down the left mouse button and move it.

The PDF Viewer gets the mouse position relative to the document by calling the PdfViewer.GetDocumentPosition method in the MouseDown (when the left mouse is pressed) and MouseMove event handlers (when the mouse is moving).

To draw a filled rectangle, the RectangleF.FromLTRB method is called in the Paint event handler. The start and end client points are obtained using the document position in the PdfViewer.GetClientPoint method.

This example also shows how to draw a rectangle using the Graphics.FillRectangle method.

View Example: How to custom draw in PDF Viewer

Form1.cs

using DevExpress.Pdf;
using System;
using System.Drawing;
using System.Windows.Forms;

namespace CustomDraw
{
    public partial class Form1 : Form
    {

        public Form1()
        {
            InitializeComponent();
            pdfViewer1.MouseDown += pdfViewer1_MouseDown;
            pdfViewer1.MouseMove += pdfViewer1_MouseMove;
            pdfViewer1.MouseUp += pdfViewer1_MouseUp;
            pdfViewer1.Paint += pdfViewer1_Paint;
        }

        bool mouseButtonPressed = false;
        PdfDocumentPosition startPosition;
        PdfDocumentPosition endPosition;

        void pdfViewer1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                startPosition = pdfViewer1.GetDocumentPosition(e.Location);
                endPosition = null;
                mouseButtonPressed = true;
                pdfViewer1.Invalidate();
            }
        }

        void pdfViewer1_MouseMove(object sender, MouseEventArgs e)
        {
            if (mouseButtonPressed)
            {
                endPosition = pdfViewer1.GetDocumentPosition(e.Location);
                pdfViewer1.Invalidate();
            }
        }

        void pdfViewer1_MouseUp(object sender, MouseEventArgs e)
        {
            mouseButtonPressed = false;
        }

        void pdfViewer1_Paint(object sender, PaintEventArgs e)
        {
            Graphics g = e.Graphics;
            g.DrawRectangle(Pens.Red, new Rectangle(150, 150, 800, 50));

            if (startPosition != null && endPosition != null)
            {
                PointF startPoint = pdfViewer1.GetClientPoint(startPosition);
                PointF endPoint = pdfViewer1.GetClientPoint(endPosition);

                using (SolidBrush blueBrush = new SolidBrush(Color.FromArgb(128, Color.Aqua)))
                {
                    g.FillRectangle(blueBrush,
                    RectangleF.FromLTRB(Math.Min(startPoint.X, endPoint.X), Math.Min(startPoint.Y, endPoint.Y),
                    Math.Max(startPoint.X, endPoint.X), Math.Max(startPoint.Y, endPoint.Y)));
                }
            }
        }
    }
}

Form1.vb

Imports DevExpress.Pdf
Imports System
Imports System.Drawing
Imports System.Windows.Forms

Namespace CustomDraw
    Partial Public Class Form1
        Inherits Form

        Public Sub New()
            InitializeComponent()
            AddHandler pdfViewer1.MouseDown, AddressOf pdfViewer1_MouseDown
            AddHandler pdfViewer1.MouseMove, AddressOf pdfViewer1_MouseMove
            AddHandler pdfViewer1.MouseUp, AddressOf pdfViewer1_MouseUp
            AddHandler pdfViewer1.Paint, AddressOf pdfViewer1_Paint
        End Sub

        Private mouseButtonPressed As Boolean = False

        Private startPosition_Renamed As PdfDocumentPosition
        Private endPosition As PdfDocumentPosition

        Private Sub pdfViewer1_MouseDown(ByVal sender As Object, ByVal e As MouseEventArgs)
            If e.Button = MouseButtons.Left Then
                startPosition_Renamed = pdfViewer1.GetDocumentPosition(e.Location)
                endPosition = Nothing
                mouseButtonPressed = True
                pdfViewer1.Invalidate()
            End If
        End Sub

        Private Sub pdfViewer1_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs)
            If mouseButtonPressed Then
                endPosition = pdfViewer1.GetDocumentPosition(e.Location)
                pdfViewer1.Invalidate()
            End If
        End Sub

        Private Sub pdfViewer1_MouseUp(ByVal sender As Object, ByVal e As MouseEventArgs)
            mouseButtonPressed = False
        End Sub

        Private Sub pdfViewer1_Paint(ByVal sender As Object, ByVal e As PaintEventArgs)
            Dim g As Graphics = e.Graphics
            g.DrawRectangle(Pens.Red, New Rectangle(150, 150, 800, 50))

            If startPosition_Renamed IsNot Nothing AndAlso endPosition IsNot Nothing Then
                Dim startPoint As PointF = pdfViewer1.GetClientPoint(startPosition_Renamed)
                Dim endPoint As PointF = pdfViewer1.GetClientPoint(endPosition)

                Using blueBrush As New SolidBrush(Color.FromArgb(128, Color.Aqua))
                    g.FillRectangle(blueBrush, RectangleF.FromLTRB(Math.Min(startPoint.X, endPoint.X), Math.Min(startPoint.Y, endPoint.Y), Math.Max(startPoint.X, endPoint.X), Math.Max(startPoint.Y, endPoint.Y)))
                End Using
            End If
        End Sub
    End Class
End Namespace