找到鼠标相对于控件的位置，而不是屏幕

Question

I have a Picture Box called BGImage . I hope that when the user clicks on this I can capture the position of the mouse relative to BGImage .

I've tried using MousePosition , only to find it gives the mouse location on the screen, not on the PictureBox.

So I also tried using PointToClient :

Dim MousePos As Point = Me.PointToClient(MousePosition)

But this gives me the location {X=1866,Y=55} whereas I actually clicked on the PictureBox at around {X=516,Y=284} .

I think the problem arises because I have full-screened my program and set the position of the PictureBox to be at the centre of the screen ( BGImage.Location = New Point((My.Computer.Screen.WorkingArea.Width / 2) - (1008 / 2), ((My.Computer.Screen.WorkingArea.Height / 2) - (567 / 2))) )

I should also mention that the size of the PictureBox is 1008 By 567 pixels and my screen resolution is 1366 by 768.

Is there any way I can get the mouse position relative to BGImage's position?

Answer 1

Add a mouse click event to your picture box
Then use the MouseEventArgs to get the mouse position inside the picture box.
This will give you the X and the Y location inside the picture box.

Dim PPoint As Point
Private Sub PictureBox1_MouseClick(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseClick
    PPoint = New Point(e.X, e.Y)
    MsgBox(Convert.ToString(PPoint))
End Sub

Answer 2

I have before the same problem and just solved with the help of some friends. Give a look Here mouse position is not correct Here its the code that give you the correct position of the Mouse Based On A Picture. Tanks to @Aaron he have give a final solution to this problem.

This will put a red dot on the exact point you click. I wonder how useful setting the cursor position will be though, as they will almost certainly move the mouse after clicking the button (inadvertently or not).

Setting the Cursor position needs to be in Screen coordinates - this converts back to client coordinates for drawing. I don't believe the PointToClient is necessary for the cursor position. In the below code, it is an unnecessary conversion, as you just go back to client coordinates. I left it in to show an example of each conversion, so that you can experiment with them.

Public Class Form1
Private PPoint As Point
Public Sub New()

' This call is required by the designer.
InitializeComponent()
PictureBox1.BackColor = Color.White
PictureBox1.BorderStyle = BorderStyle.Fixed3D
AddHandler PictureBox1.MouseClick, AddressOf PictureBox1_MouseClick
AddHandler Button8.Click, AddressOf Button8_Click
' Add any initialization after the InitializeComponent() call.

End Sub

Private Sub Button8_Click(sender As Object, e As EventArgs)
Dim g As Graphics = PictureBox1.CreateGraphics()
Dim rect As New Rectangle(PictureBox1.PointToClient(PPoint), New Size(1, 1))
g.DrawRectangle(Pens.Red, rect)
End Sub

Private Sub PictureBox1_MouseClick(sender As Object, e As MouseEventArgs)
PPoint = PictureBox1.PointToScreen(New Point(e.X, e.Y))
Label8.Text = PPoint.X.ToString()
Label9.Text = PPoint.Y.ToString()

End Sub
End Class

Answer 3

Instead of using:

Dim MousePos As Point = Me.PointToClient(MousePosition)

You should be using:

Dim MousePos As Point = BGImage.PointToClient(MousePosition)

It will give you mouse position in BGImage coordinates, whereas the first code gives you the mouse position in the Form's coordinates.