Mouse clicking

[ryans]

I'm trying to store the coordinates of where the left mouse button is clicked.
the button will be clicked in a picture box, and then these coordinates will be used to draw a rectangle on the screen.
so far i know that i can use e.X and e.Y to get the position.

[Pirate]

Dim Coordinates As Point
 
    Private Sub PictureBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown
        If e.Button.Left Then
 
            Coordinates = New Point(e.X, e.Y)
            'or
            Coordinates = New Point(MousePosition.X, MousePosition.Y)
        End If
    End Sub

[MrPolite]

something like this... too many flickers though

Private startX, startY As Integer
    Private isDragging As Boolean = False
    Private Sub picBoard_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles picBoard.MouseDown
        startX = e.X
        startY = e.Y
        isDragging = True
    End Sub
 
    Private Sub picBoard_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles picBoard.MouseMove
        If isDragging Then
            Dim gr As Graphics = picBoard.CreateGraphics
            gr.Clear(picBoard.BackColor)
 
            Dim rect As New Rectangle(startX, startY, e.X - startX, e.Y - startY)
            gr.FillRectangle(Brushes.Blue, rect)
            gr.DrawRectangle(Pens.Red, rect)
 
            gr.Dispose()
        End If
    End Sub
 
    Private Sub picBoard_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles picBoard.MouseUp
        isDragging = False
    End Sub

picBoard is the picturebox

[ryans]

I get an error from this code:

Private Sub picBoard_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles picImage.MouseMove
If isDragging Then
Dim gr As Graphics = picImage.CreateGraphics
gr.Clear(picImage.BackColor)

Dim rect As New Rectangle(startX, startY, e.X - startX, e.Y - startY)
gr.DrawRectangle(Pens.Red, rect)
gr.FillRectangle(Brushes.Transparent, rect)
Dim bmpCropped As New Bitmap(e.X - startX, e.Y - startY)

Dim grBitmap As Graphics = Graphics.FromImage(bmpCropped)

grBitmap.DrawImage(picImage.Image, 0, 0, rect, _
GraphicsUnit.Pixel)
picImage.Image = bmpCropped
picImage.SizeMode = PictureBoxSizeMode.Normal
gr.Dispose()
End If
End Sub


This is supposed to crop the image from the rectangle drawn.
the error is from this line of code because it accepts invalid inputs i think.

Dim bmpCropped As New Bitmap(e.X - startX, e.Y - startY)

[MrPolite]

Originally posted by ryans
the error is from this line of code because it accepts invalid inputs i think.

Dim bmpCropped As New Bitmap(e.X - startX, e.Y - startY)

what is the error message first of all?
second, I would guess that e.X is smaller than startX, or the same thing about e.y (meaning you dragged the mouse up, or left, while that code only works when you drag the mouse down or to the right). If it's the case they you're basically asking .NET to create a bitmap with a negative size, which doesnt make sense... you just have to switch the variables around depending on what the user does

[ryans]

Originally posted by MrPolite
what is the error message first of all?
second, I would guess that e.X is smaller than startX, or the same thing about e.y (meaning you dragged the mouse up, or left, while that code only works when you drag the mouse down or to the right). If it's the case they you're basically asking .NET to create a bitmap with a negative size, which doesnt make sense... you just have to switch the variables around depending on what the user does

This is the error message given when i try and draw a rectangle

An unhandled exception of type 'System.ArgumentException' occurred in system.drawing.dll

Additional information: Invalid parameter used.