draw an image in picturebox

Question

HI

I want to draw an image with mouse event in a picbox. similar to this:

Answer 1

Hi,

You can refer to the following code.

Imports System.Drawing.Drawing2D

Public Class Form1
    Private NewImg As Img1
    Private Imgs As New List(Of Img1)

    Private Sub PictureBox1_MouseDown(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseDown
        NewImg = New Img1("C:\Users\Administrator\Desktop\Cat.jfif", e.Location, e.Location)
        Imgs.Add(NewImg)
    End Sub

    Private Sub PictureBox1_MouseMove(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseMove
        If NewImg Is Nothing Then Return
        NewImg.Point2 = e.Location
        PictureBox1.Invalidate()
    End Sub

    Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint

        e.Graphics.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias
        For Each Img As Img1 In Imgs
            Img.Draw(e.Graphics)
        Next
    End Sub

    Private Sub PictureBox1_MouseUp(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseUp
        NewImg = Nothing
    End Sub

    Private Sub PictureBox1_SizeChanged(sender As Object, e As EventArgs) Handles PictureBox1.SizeChanged
        PictureBox1.Invalidate()
    End Sub
End Class

Class Img1
    Private pt1, pt2 As Point
    Private img As Image
    Public Sub New(imageloc As String, startPoint As Point, endPoint As Point)
        img = Image.FromFile(imageloc)
        Point1 = startPoint
        Point2 = endPoint

    End Sub
    Public Property Point1 As Point
        Get
            Return pt1
        End Get
        Set(value As Point)
            pt1 = value
        End Set
    End Property

    Public Property Point2 As Point
        Get
            Return pt2
        End Get
        Set(value As Point)
            pt2 = value
        End Set
    End Property

    Public Sub Draw(gr As Graphics)
        Dim newsize As New Size(Point2.X - Point1.X, Point2.Y - Point1.Y)
        Dim newpt As New Point(Math.Min(pt1.X, pt2.X), Math.Min(pt1.Y, pt2.Y))
        gr.DrawImage(resizeImage(img, newsize), newpt)
    End Sub
    Private Shared Function resizeImage(ByVal imgToResize As Image, ByVal size As Size) As Image
        Dim sourceWidth As Integer = imgToResize.Width
        Dim sourceHeight As Integer = imgToResize.Height
        Dim nPercent As Single = 0
        Dim nPercentW As Single = 0
        Dim nPercentH As Single = 0
        nPercentW = (CSng(size.Width) / CSng(sourceWidth))
        nPercentH = (CSng(size.Height) / CSng(sourceHeight))

        Dim destWidth As Integer = CInt((sourceWidth * nPercentW))
        Dim destHeight As Integer = CInt((sourceHeight * nPercentH))

        If destHeight = 0 OrElse destWidth = 0 Then
            Dim b As Bitmap = New Bitmap(1, 1)
            Dim g As Graphics = Graphics.FromImage(CType(b, Image))
            g.InterpolationMode = InterpolationMode.HighQualityBicubic
            g.DrawImage(imgToResize, 0, 0, Math.Abs(destWidth), Math.Abs(destHeight))
            g.Dispose()
            Return CType(b, Image)

        ElseIf destHeight > 0 AndAlso destWidth > 0 Then
            Console.WriteLine(destHeight & "," & destWidth)
            Dim b As Bitmap = New Bitmap(Math.Abs(destWidth), Math.Abs(destHeight))
            Dim g As Graphics = Graphics.FromImage(CType(b, System.Drawing.Image))
            g.InterpolationMode = InterpolationMode.HighQualityBicubic
            g.DrawImage(imgToResize, 0, 0, Math.Abs(destWidth), Math.Abs(destHeight))
            g.Dispose()
            Return CType(b, Image)
        ElseIf destHeight > 0 AndAlso destWidth < 0 Then
            Dim b As Bitmap = New Bitmap(Math.Abs(destWidth), Math.Abs(destHeight))
            Dim g As Graphics = Graphics.FromImage(CType(b, Image))
            g.InterpolationMode = InterpolationMode.HighQualityBicubic
            g.DrawImage(imgToResize, 0, 0, Math.Abs(destWidth), Math.Abs(destHeight))
            g.Dispose()
            b.RotateFlip(RotateFlipType.RotateNoneFlipX)
            Return CType(b, Image)
        ElseIf destHeight < 0 AndAlso destWidth > 0 Then
            Dim b As Bitmap = New Bitmap(Math.Abs(destWidth), Math.Abs(destHeight))
            Dim g As Graphics = Graphics.FromImage(CType(b, Image))
            g.InterpolationMode = InterpolationMode.HighQualityBicubic
            g.DrawImage(imgToResize, 0, 0, Math.Abs(destWidth), Math.Abs(destHeight))
            g.Dispose()
            b.RotateFlip(RotateFlipType.RotateNoneFlipY)
            Return CType(b, Image)
        Else
            Dim b As Bitmap = New Bitmap(Math.Abs(destWidth), Math.Abs(destHeight))
            Dim g As Graphics = Graphics.FromImage(CType(b, Image))
            g.InterpolationMode = InterpolationMode.HighQualityBicubic
            g.DrawImage(imgToResize, 0, 0, Math.Abs(destWidth), Math.Abs(destHeight))
            g.Dispose()
            b.RotateFlip(RotateFlipType.RotateNoneFlipXY)
            Return CType(b, Image)
        End If
    End Function
End Class

Best Regards.
Jiachen Li
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