Drawing on mouse location

mike Delvotti

Guys i'm trying to print text over the top of a background graphic where the mouse is clicked on a click event, so for instance if the radio button is true where ever the mouse is clicked it will print "DL" on the screen.

Something like:

if (radioButton_DL == true)
{
Print "DL" at mouse coordinates on screen.
}

What would be the best way to achieve this?

6 Replies

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Vulpes15y ago
Accepted answer
Hi Mike,

Yes, if you want the drawing to be persisted when you save the image, you have to draw on the image in the picturebox rather than over the top of it.

I couldn't really see why you needed two Graphics objects. One should be enough:

private void pictureBox1_MouseClick(object sender, MouseEventArgs e)
{
Bitmap myBitmap = new Bitmap(pictureBox1.Image);
Graphics g = Graphics.FromImage(myBitmap);
g.DrawString("D", new Font("Arial", 20), Brushes.Red, e.Location);
g.Dispose();
pictureBox1.Image = myBitmap;
}
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mike Delvotti15y ago
Ah, guys I think I found the solution - I realized that I was only drawing over the top of the picture box rather than the image itself, I got it working using the below code (although there may be a better way?)

Bitmap myBitmap = new Bitmap(pictureBox1.Image);
Graphics g1 = Graphics.FromImage(myBitmap);
Graphics g2 = this.pictureBox1.CreateGraphics();
g1.DrawString("D", new Font("Arial", 20), Brushes.Red, e.Location);
g2.DrawString("D", new Font("Arial", 20), Brushes.Red, e.Location);
g1.Dispose();
g2.Dispose();
this.pictureBox1.Image = myBitmap;
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mike Delvotti15y ago
Hi Vulpes, I'm trying to apply the same theory in this topic over a background image in a picture box, it works and draws over the top of the image, but when I save the image back to the database the text I have drawn over the top of the image in pictureBox1 doesn't get applied to the image?

Could I be missing another function?
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mike Delvotti15y ago
That works great on Form1 - however i did foget to mention i want it to work inside splitcontainer.panel 1, what property would I have to use?

Ah, I worked it out on this line:
Graphics
g = this.splitContainer1.Panel1.CreateGraphics();
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Vulpes15y ago
It's not as simple as that because you need to persist the text you've drawn when the form itself gets redrawn. Try this:

List points = new List();

private void Form1_MouseClick(object sender, MouseEventArgs e)
{
if (radioButton_DL.Checked)
{
Graphics g = this.CreateGraphics();
g.DrawString("DL", this.Font, Brushes.Red, e.Location);
points.Add(e.Location);
g.Dispose();
}
}

private void Form1_Paint(object sender, PaintEventArgs e)
{
if (points.Count > 0)
{
Graphics g = e.Graphics;
foreach (Point p in points)
{
g.DrawString("DL", this.Font, Brushes.Red, p);
}
}
}
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Roy S15y ago
You could take the MouseClick event of wherever the user would click on and then draw "DL" using e.Location.

    private void Form1_MouseClick(object sender, MouseEventArgs e)
    {
        if (radDL.Checked)
        {
            Graphics g = this.CreateGraphics();
            g.DrawString("DL", new Font("Arial", 20), Brushes.Red, e.Location);
        }
    }
0