Develop Reference

One handler for several events of different classes?

I want to create a program that will draw a circle at the cursor position when it is moved.
I tried to create a method that will be an event handler for MouseEventHandler and PaintEventHandler, but I got the error cs0123. How to fix it, and is it even possible?
My code:
Pen pen = new Pen(Color.Black, 3)
private void Form1_Load(object sender, EventArgs e)
{
PictureBox pictureBox1 = new PictureBox();
pictureBox1.Dock = DockStyle.Fill;
pictureBox1.Paint += new PaintEventHandler(My_func);//cs0123
pictureBox1.MouseMove += new MouseEventHandler(My_func);//cs0123
}
private void My_func(object sender, PaintEventArgs pe, MouseEventArgs me)
{
Graphics g = e.Graphics;
g.DrawEllipse(pen, pictureBox1.PointToClient(Cursor.Position), 3, 3);
}

You can't just pop in random arguments to eventhandlers with fixed signatures. Both of them expect 2 arguments only, PaintEventHandler MouseEventHandler so they can't be handled by a method which expects three arguments.
Either create two different eventhandlers, one for each event.
pictureBox1.Paint += new PaintEventHandler(pehandler);
pictureBox1.MouseMove += new MouseEventHandler(mehandler);
private void mehandler(object sender, MouseEventArgs args) {
...
}
private void pehandler(object sender, PaintEventArgs args) {
...
}
Or create a more generic one, which fits the signature
private void myfunc(object sender, EventArgs args) {
if (args is PaintEventArgs) {
//do something with the args
}
else if (args is MouseEventArgs {
//do something with the args
}
}

The name 'Drawline' does not exist in the current context

namespace MiniPaint
{
public partial class Form1 : Form
{
Graphics g;
Pen p = new Pen(Color.Black, 1);
Point sp = new Point(0, 0);
Point ep = new Point(0, 0);
int k = 0;
public Form1()
{
InitializeComponent();
}
private void panel1_Paint(object sender, PaintEventArgs e)
{
}
private void red_Click(object sender, EventArgs e)
{
p.Color = red.BackColor;
default1.BackColor = red.BackColor;
}
private void green_Click(object sender, EventArgs e)
{
p.Color = green.BackColor;
default1.BackColor = green.BackColor;
}
private void blue_Click(object sender, EventArgs e)
{
p.Color = blue.BackColor;
default1.BackColor = blue.BackColor;
}
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
sp = e.Location;
if (e.Button == MouseButtons.Left) ;
k = 1;
}
private void Form1_MouseUp(object sender, MouseEventArgs e)
{
k = 0;
}
private void Form1_MouseMove(object sender, MouseEventArgs e)
{
if (k == 1)
{
ep = e.Location;
g = this.CreateGraphics();
g = DrawLine(p, sp, ep);
}
sp = ep;
}
}
}
Hello guys! Im having a problem with this code and the title is my error. Im pretty new with c# and graphics too, I understand this code,(partially wrote it myself but this error is driving me crazy). Can anyone tell me where im mistaken and explain it to me? Thanks in advance! And btw is there an easy way for example via button to delete everything thats going to be painted on the form and how can i do that?

DrawLine can be used on a Graphics object and also it returns void. So this:
g = DrawLine(p, sp, ep);
Should be something like:
g.DrawLine(p, sp, ep);

You are using the DrawLine method wrong. It draws a line on Graphics instance. You should use something like this:
g.DrawLine(p, sp, ep);

How to add textboxs to the dynamically created pictureboxes

I have a program which dynamically creates movable pictureboxes when I click on buttons. I need to do something like when I click on the picturebox, this click adds to my dynamically created picturebox a new textbox when I can write descripiton of this picturebox(name,...). This textbox should be able to move with picturebox.
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
List<PictureBox> pictureboxes = new List<PictureBox>();
public Form1()
{
InitializeComponent();
}
private void AddPictureBox(string imagePath)
{
var pb = new PictureBox();
pb.Name = "picturebox" + pictureboxes.Count;
pb.Location = new Point(pictureboxes.Count * 100, 100);
pb.Size = new Size(70, 70);
pb.BorderStyle = BorderStyle.None;
pb.SizeMode = PictureBoxSizeMode.StretchImage;
this.Controls.Add(pb);
pb.Image = Image.FromFile(imagePath);
pb.Refresh();
pb.MouseDown += new MouseEventHandler(picMouseDown);
pb.MouseMove += new MouseEventHandler(picMouseMove);
pb.MouseUp += new MouseEventHandler(picMouseUp);
pictureboxes.Add(pb);
Invalidate();
}
private void router_Click(object sender, EventArgs e)
{
AddPictureBox(#"D:\\router.jpg");
}
private void Form1_Load(object sender, EventArgs e)
{
}
int x = 0;
int y = 0;
bool drag = false;
private void picMouseDown(object sender, MouseEventArgs e)
{
// Get original position of cursor on mousedown
x = e.X;
y = e.Y;
drag = true;
}
private void picMouseMove(object sender, MouseEventArgs e)
{
if (drag)
{
PictureBox pb = (PictureBox)sender;
// Get new position of picture
pb.Top += e.Y - y;
pb.Left += e.X - x;
pb.BringToFront();
Invalidate();
}
}
private void picMouseUp(object sender, MouseEventArgs e)
{
drag = false;
}
private void switch1_Click(object sender, EventArgs e)
{
AddPictureBox(#"D:\HP ProBook 450\Desktop\Grafika\switch1.png");
}
private void panel1_Paint(object sender, PaintEventArgs e)
{
}
private void pc_Click(object sender, EventArgs e)
{
AddPictureBox(#"D:\HP ProBook 450\Desktop\pc.jpg");
}
private void server_Click(object sender, EventArgs e)
{
AddPictureBox(#"D:\HP ProBook 450\Desktop\server.png");
}
}
Thanks for any help :).

You can add a TextBox to a PictureBox in code like this:
TextBox newTextBox = new TextBox();
newTextBox.Parent = yourPictureBox;
// place it e.g. to the left bottom:
newTextBox.Location = new Point(10, yourPictureBox.Height - newTextBox.Height);
Note that this will add the TextBox to the Controls collection of the PB; so it will sit on top of the PictureBox; so, yes, it will move with the PictureBox but it will also hide a part or the PB!
If instead you simply want to group them, add them both to something like a Panel, again by setting that as their Parent!
Also note that you can't do this in the Designer; PictureBox is not really meant to act as a Container..
It doesn't matter how the PictureBox was created, as long as you have a reference to it.

C# bitmap drawing doesn't render to the screen

I am trying to write a drawing program for use with a tablet. For this I need fall-off and transparency for use with pressures. So I am using the bitmap system in C# for image construction.
I cannot seem to get my drawing code at the moment to display anything. It is being rendered to a picture box. I know there is some stuff being input to the bitmap as it shows up when I do a bitmap save.
I have had a look around an pretty much all C# drawing questions refer to using the line drawing or ellipse drawing stuff as opposed to bitmaps
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace paint1
{
public partial class Form2 : Form
{
public Bitmap m_bitmap;
public bool m_penDown;
public int m_lastX;
public int m_lastY;
public int m_currentX;
public int m_currentY;
public Form2()
{
InitializeComponent();
// Create the bitmap area
m_bitmap = new Bitmap(this.Width, this.Height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
m_penDown = false;
Graphics m_graphics = Graphics.FromImage(m_bitmap);
m_lastX = System.Windows.Forms.Cursor.Position.X;
m_lastY = System.Windows.Forms.Cursor.Position.Y;
m_currentX = System.Windows.Forms.Cursor.Position.X;
m_currentY = System.Windows.Forms.Cursor.Position.Y;
}
private void Form2_Load(object sender, EventArgs e)
{
}
private void Form2_Paint(object sender, PaintEventArgs e)
{
Graphics objGraphics;
//You can't modify e.Graphics directly.
objGraphics = e.Graphics;
// Draw the contents of the bitmap on the form.
objGraphics.DrawImage(m_bitmap, 0, 0,
m_bitmap.Width,
m_bitmap.Height);
objGraphics.Dispose();
}
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
m_penDown = true;
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
m_penDown = false;
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
m_lastX = m_currentX;
m_lastY = m_currentY;
m_currentX = System.Windows.Forms.Cursor.Position.X;
m_currentY = System.Windows.Forms.Cursor.Position.Y;
if(m_penDown)
m_bitmap.SetPixel(m_currentX, m_currentY, Color.Gray);
}
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
Form2_Paint(sender, e);
this.pictureBox1.Image = m_bitmap;
}
private void Form2_KeyUp(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Space)
{
m_bitmap.Save(#"C:\Users\rpettefar\Documents\My Dropbox\Programming\paint1\preview.bmp", System.Drawing.Imaging.ImageFormat.Bmp);
}
}
}
}
I am a bit new to c# so I am very open to any other issues or things that may come to your attention too.

You will have to assign your bitmap to the picture box.
myPictureBox.Image = m_bitmap;
You can do that after you changed the bitmap or assign it once and then invalidate your PictureBox.
myPictureBox.Invalidate();
This tells your form to refresh the picture on the screen. There is no need to override OnPaint. Draw to the bitmap using the Graphics object you created in the constructor of the form (if you want to make more complicated things than just drawing single pixels). The PictureBox will do the rest.

It looks like there's at least two ways you're trying to get the image on screen; can't say immediately what's wrong, but I would say definitely get rid of that objGraphics.Dispose(); line - you didn't create the Graphics (you were passed it), so you shouldn't Dispose it.

I cleaned up your code a bit. You probably shouldn't use a picturebox for this.
Here is a form with just a panel:
public partial class Form1 : Form
{
public Bitmap m_bitmap;
public Point m_lastPoint = Point.Empty;
public Form1()
{
InitializeComponent();
m_bitmap = new Bitmap(panel1.ClientSize.Width, panel1.ClientSize.Height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
using (Graphics g = Graphics.FromImage(m_bitmap))
g.Clear(SystemColors.Window);
}
private void panel1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.DrawImage(m_bitmap, new Point(0, 0));
}
private void panel1_MouseDown(object sender, MouseEventArgs e)
{
m_lastPoint = e.Location;
}
private void panel1_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
using (Graphics g = Graphics.FromImage(m_bitmap))
g.DrawLine(Pens.Black, m_lastPoint, e.Location);
m_lastPoint = e.Location;
panel1.Invalidate();
}
}
}

The other posters have largely answered the question, but in my experience, I'd add that you'll likely get some flicker with this method. If you do, one thing you can do to help with this is sub-class your rendering target and enable double buffering. For a picture box, it would look something like this:
public class DoubleBufferedPictureBox : PictureBox
{
/// <summary>
/// Creates an instance of the DoubleBufferedPictureBox.
/// </summary>
public DoubleBufferedPictureBox() : base()
{
this.SetStyle(ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint | ControlStyles.DoubleBuffer, true);
}
}

How to get the Coordinates of a Custom Image Cursor in c#?

Bitmap hh = (Bitmap)System.Drawing.Bitmap.FromFile("example.png");
Graphics.FromImage(hh);
IntPtr ptr = hh.GetHicon();
Cursor c = new Cursor(ptr);
this.Cursor = c;
I use this code to create a custom image cursor. I want to retrieve the coordinates of this custom image cursor when on a Click event. So that these coordinates can be used to draw the image of this cursor in a picture box when clicked on the image loaded in the picture box. I'm doing this in C#.
I tried another approach
public partial class Form1 : Form
{
private Bitmap _bmp = new Bitmap(250, 250);
public Form1()
{
InitializeComponent();
panel1.MouseDown += new MouseEventHandler(panel1_MouseDown);
panel1.Paint += new PaintEventHandler(panel1_Paint);
using (Graphics g = Graphics.FromImage(_bmp))
g.Clear(SystemColors.Window);
}
private void pictureBox1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
Point mouseDownLocation = new Point(e.X, e.Y);
label1.Text = mouseDownLocation.X.ToString();
}
private void panel1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.DrawImage(_bmp, new Point(0, 0));
}
private void panel1_MouseDown(object sender, MouseEventArgs e)
{
using (Graphics g = Graphics.FromImage(_bmp))
{
g.DrawString("Mouse Clicked Here!", panel1.Font, Brushes.Black, e.Location);
}
panel1.Invalidate();
}
private void button1_Click(object sender, EventArgs e)
{
panel1.Image.Save(#"C:\test.jpg", ImageFormat.Jpeg);
}
But when i try so save the image i get an Exception: Object reference not set to an instance of an object.
Please note that panel1 in the code above refers to a picture box

To get the coordinates of the mouse on a PictureBox you should not handle the OnClick event but the OnMouseDown, for example in this way:
private void pb_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
Point mouseDownLocation = new Point(e.X, e.Y);
}
now you have the mouseDownLocation which contains the coordinates you were looking for.

i know the way to get the coordinate of mouse you can code it like
Cursor.Position.X and Cursor.Position.Y to get the Coordinate under the mouse