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Update bitmap on button click

I am drawing a box with certain measurements and updating the angle at which it is viewed which I set as a double 'offset'. I am trying to get the view to change as I click a button to increase its offset. How would I update the bitmap to reflect the button click.
"
public void Form1_Load(object sender, EventArgs e)
{
myBitmap = new Bitmap(this.ClientRectangle.Width,
this.ClientRectangle.Height);
graphicsObj = Graphics.FromImage(myBitmap);
Pen linePen = new Pen(Color.Red, 3);
graphicsObj.Drawline(linePen, 50, 50, 100, 50);
public void Form1_Paint(object sender, PaintEventArgs e)
{
Graphics graphicsObj = e.Graphics;
graphicsObj.DrawImage(myBitmap, 0, 0, myBitmap.Width, myBitmap.Height);
}
public void button1_Click(object sender, EventArgs e)
{
offsetButton = offsetButton + .10;
**call or update bitmap**
}
"

add multiple picturebox to a main Picturebox and draw them

I have a main PictureBox which adding to it , an other picture boxes; I pass the parent to the children and add them to the parent as follow :
public class VectorLayer : PictureBox
{
Point start, end;
Pen pen;
public VectorLayer(Control parent)
{
pen = new Pen(Color.FromArgb(255, 0, 0, 255), 8);
pen.StartCap = LineCap.ArrowAnchor;
pen.EndCap = LineCap.RoundAnchor;
parent.Controls.Add(this);
BackColor = Color.Transparent;
Location = new Point(0, 0);
}
public void OnPaint(object sender, PaintEventArgs e)
{
e.Graphics.DrawLine(pen, end, start);
}
public void OnMouseDown(object sender, MouseEventArgs e)
{
start = e.Location;
}
public void OnMouseMove(object sender, MouseEventArgs e)
{
end = e.Location;
Invalidate();
}
public void OnMouseUp(object sender, MouseEventArgs e)
{
end = e.Location;
Invalidate();
}
}
and am handling those On Events from inside the main PictureBox, now in the main PictureBox am handling on the Paint event as follow:
private void PicBox_Paint(object sender, PaintEventArgs e)
{
//current layer is now an instance of `VectorLayer` which is a child of this main picturebox
if (currentLayer != null)
{
currentLayer.OnPaint(this, e);
}
e.Graphics.Flush();
e.Graphics.Save();
}
but when I draw nothing appears , when I do Alt+Tab lose the focus from it , I see my vector , when I try to draw again and lose focus nothing happens..
why is that weird behavior and how do I fix it?

You have forgotten to hook up your events.
Add these lines to your class:
MouseDown += OnMouseDown;
MouseMove += OnMouseMove;
MouseUp += OnMouseUp;
Paint += OnPaint;
Not sure if you don't maybe want this in the MouseMove:
public void OnMouseMove(object sender, MouseEventArgs e)
{
if (e.Button == System.Windows.Forms.MouseButtons.Left)
{
end = e.Location;
Invalidate();
}
}
Aslo these lines are useless and should be removed:
e.Graphics.Flush();
e.Graphics.Save();
GraphicsState oldState = Graphics.Save would save the current state, ie the setting of the current Graphics object. Useful if you need to toggle between several states, maybe scales or clipping or rotation or translation etc.. But not here!
Graphics.Flush flushes all pending graphics operations, but there is really no reason to suspect that there are any in your application.

Partial screenshot with rectangle of selection c#

I'm trying to take a partial screenshot of the screen and put it in a picturebox. The user has to draw a rectangle and then i have to get the portion inside the rectangle.
protected override void OnMouseDown(MouseEventArgs e)
{
mRect = new Rectangle(e.X, e.Y, 0, 0);
this.Invalidate();
}
protected override void OnMouseMove(MouseEventArgs e)
{
if( e.Button == MouseButtons.Left)
{
mRect = new Rectangle(mRect.Left, mRect.Top, e.X - mRect.Left, e.Y - mRect.Top);
this.Invalidate();
}
}
protected override void OnPaint(PaintEventArgs e)
{
using(Pen pen = new Pen(Color.Red, 1))
{
e.Graphics.DrawRectangle(pen, mRect);
}
}
With this code i can draw a recangle, but i don't know how to do the screenshot. Maybe with the fonction CopyToScreen?
If someone have an idea?
Thanks!

Here is some code I use - it grabs the whole desktop
public static Bitmap GetScreenAsBmp()
{
int min_x=0, max_x=0, min_y=0, max_y=0;
foreach (Screen s in Screen.AllScreens)
{
min_x = System.Math.Min(min_x, s.Bounds.Left);
max_x = System.Math.Max(max_x, s.Bounds.Right);
min_y = System.Math.Min(min_y, s.Bounds.Top);
max_y = System.Math.Max(max_y, s.Bounds.Bottom);
}
Bitmap bmp = new Bitmap(max_x - min_x, max_y - min_y);
Graphics dst_dc = Graphics.FromImage(bmp);
dst_dc.CopyFromScreen(min_x, min_y, 0, 0, new Size(max_x - min_x, max_y - min_y));
dst_dc.Dispose();
return bmp;
}

This is a complete solution for the problem.
It is triggered by a Button and then:
creates and styles a second Form which
is transparent without borders etc and fills the screen
has all events needed to draw a Rectangle
copies the screen after the rectangle is drawn, i.e. after the MouseUp
and copies the Bitmap into the Image of a PictureBox on the 1st Form.
Finally it closes the 2nd form. During the screencopy process both windows are hidden, so you can grab the screen itself with all its content.
Note that many video overlays can't be captured this way!
Note that this code always captures from the 1st screen!
For best usability the users should somehow be informed that he is expected to draw the frame after the Button is pressed and the window has disappeared!
To use it simply add a Button and a PictureBox to your Form..
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
Form form2;
Point MD = Point.Empty;
Rectangle rect = Rectangle.Empty;
private void button2_Click(object sender, EventArgs e)
{
Hide();
form2 = new Form();
form2.BackColor = Color.Wheat;
form2.TransparencyKey = form2.BackColor;
form2.ControlBox = false;
form2.MaximizeBox = false;
form2.MinimizeBox = false;
form2.FormBorderStyle = FormBorderStyle.None;
form2.WindowState = FormWindowState.Maximized;
form2.MouseDown += form2_MouseDown;
form2.MouseMove += form2_MouseMove;
form2.Paint += form2_Paint;
form2.MouseUp += form2_MouseUp;
form2.Show();
}
void form2_MouseDown(object sender, MouseEventArgs e)
{
MD = e.Location;
}
void form2_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button !=MouseButtons.Left) return;
Point MM = e.Location;
rect = new Rectangle(Math.Min(MD.X, MM.X), Math.Min(MD.Y, MM.Y),
Math.Abs(MD.X - MM.X), Math.Abs(MD.Y - MM.Y));
form2.Invalidate();
}
void form2_Paint(object sender, PaintEventArgs e)
{
e.Graphics.DrawRectangle(Pens.Red, rect);
}
void form2_MouseUp(object sender, MouseEventArgs e)
{
form2.Hide();
Screen scr = Screen.AllScreens[0];
Bitmap bmp = new Bitmap(rect.Width, rect.Height);
using (Graphics G = Graphics.FromImage(bmp))
{
G.CopyFromScreen(rect.Location, Point.Empty, rect.Size,
CopyPixelOperation.SourceCopy);
pictureBox1.Image = bmp;
}
form2.Close();
Show();
}
}

How to select an area on a PictureBox.Image with mouse in C#

i just wanted to put a selection on my picturebox.image but this has just become worse than some little annoying situation. I thought on another picture box over the main picturebox but it seemed so lazy work to me. I need to know if there is a way to create a selection area (which is gonna be half transparent blue area) on a picturebox.image which im gonna draw with mouse and it shouldnt change the image im working on.
sample:
// Start Rectangle
//
private void pictureBox1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
// Determine the initial rectangle coordinates...
RectStartPoint = e.Location;
Invalidate();
}
// Draw Rectangle
//
private void pictureBox1_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e)
{
if (e.Button != MouseButtons.Left)
return;
Point tempEndPoint = e.Location;
Rect =
new Rectangle(
Math.Min(RectStartPoint.X, tempEndPoint.X),
Math.Min(RectStartPoint.Y, tempEndPoint.Y),
Math.Abs(RectStartPoint.X - tempEndPoint.X),
Math.Abs(RectStartPoint.Y - tempEndPoint.Y));
Invalidate(Rect);
}
// Draw Area
//
private void pictureBox1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{
// Draw the rectangle...
if (pictureBox1.Image != null)
{
Brush brush = new SolidBrush(Color.FromArgb(128, 72, 145, 220));
e.Graphics.FillRectangle(brush, Rect);
}
}

I used your code, you were nearly there. You needed to Invalidate the pictureBox1 instead of the rectangle. I also added a check for the Rect so it doesn't get drawn when it's not initialized or has no size.
Another important change: I created the Rectangle only once and I adjusted its location and size. Less garbage to clean up!
EDIT
I added a mouse right-click handler for the Rectangle.
private Point RectStartPoint;
private Rectangle Rect = new Rectangle();
private Brush selectionBrush = new SolidBrush(Color.FromArgb(128, 72, 145, 220));
// Start Rectangle
//
private void pictureBox1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
// Determine the initial rectangle coordinates...
RectStartPoint = e.Location;
Invalidate();
}
// Draw Rectangle
//
private void pictureBox1_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e)
{
if (e.Button != MouseButtons.Left)
return;
Point tempEndPoint = e.Location;
Rect.Location = new Point(
Math.Min(RectStartPoint.X, tempEndPoint.X),
Math.Min(RectStartPoint.Y, tempEndPoint.Y));
Rect.Size = new Size(
Math.Abs(RectStartPoint.X - tempEndPoint.X),
Math.Abs(RectStartPoint.Y - tempEndPoint.Y));
pictureBox1.Invalidate();
}
// Draw Area
//
private void pictureBox1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{
// Draw the rectangle...
if (pictureBox1.Image != null)
{
if (Rect != null && Rect.Width > 0 && Rect.Height > 0)
{
e.Graphics.FillRectangle(selectionBrush, Rect);
}
}
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Right)
{
if (Rect.Contains(e.Location))
{
Debug.WriteLine("Right click");
}
}
}

private int xUp, yUp, xDown,yDown;
private Rectangle rectCropArea;
private void SrcPicBox_MouseUp(object sender, MouseEventArgs e)
{
//pictureBox1.Image.Clone();
xUp = e.X;
yUp = e.Y;
Rectangle rec = new Rectangle(xDown,yDown,Math.Abs(xUp xDown),Math.Abs(yUp-yDown));
using (Pen pen = new Pen(Color.YellowGreen, 3))
{
SrcPicBox.CreateGraphics().DrawRectangle(pen, rec);
}
rectCropArea = rec;
}
private void SrcPicBox_MouseDown(object sender, MouseEventArgs e)
{
SrcPicBox.Invalidate();
xDown = e.X;
yDown = e.Y;
}
private void btn_upload_Click(object sender, EventArgs e)
{
OpenFileDialog opf = new OpenFileDialog();
// PictureBox SrcPicBox = new PictureBox();
opf.Filter = "ALL images(*.*)|*.*";
if (opf.ShowDialog() == DialogResult.OK)
{
string name = opf.SafeFileName;
string filepath = opf.FileName;
File.Copy(filepath, name, true);
SrcPicBox.Image = Image.FromFile(opf.FileName);
}
private void btn_crop_Click(object sender, EventArgs e)
{
pictureBox3.Refresh();
//Prepare a new Bitmap on which the cropped image will be drawn
Bitmap sourceBitmap = new Bitmap(SrcPicBox.Image, SrcPicBox.Width, SrcPicBox.Height);
Graphics g = pictureBox3.CreateGraphics();
//Draw the image on the Graphics object with the new dimesions
g.DrawImage(sourceBitmap, new Rectangle(0, 0, pictureBox3.Width, pictureBox3.Height), rectCropArea, GraphicsUnit.Pixel);
sourceBitmap.Dispose();
}

C# graphics flickering

I am working on kind of drawing program but I have a problem with flickering while moving a mouse cursor while drawing a rubberband line. I hope you can help me to remove that flickering of line, here is the code:
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 GraphicsTest
{
public partial class Form1 : Form
{
int xFirst, yFirst;
Bitmap bm = new Bitmap(1000, 1000);
Graphics bmG;
Graphics xG;
Pen pen = new Pen(Color.Black, 1);
bool draw = false;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
bmG = Graphics.FromImage(bm);
xG = this.CreateGraphics();
bmG.Clear(Color.White);
}
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
xFirst = e.X;
yFirst = e.Y;
draw = true;
}
private void Form1_MouseUp(object sender, MouseEventArgs e)
{
bmG.DrawLine(pen, xFirst, yFirst, e.X, e.Y);
draw = false;
xG.DrawImage(bm, 0, 0);
}
private void Form1_MouseMove(object sender, MouseEventArgs e)
{
if (draw)
{
xG.DrawImage(bm, 0, 0);
xG.DrawLine(pen, xFirst, yFirst, e.X, e.Y);
}
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
xG.DrawImage(bm, 0, 0);
}
}
}

First don't use CreateGraphics() unless you absolutely have to. Bind an event handler to OnPaint and call Invalidate() when you want to refresh the surface.
If you don't want it to flicker you'll need to double buffer your drawing surface. The easiest way to do this is to set your form's DoubleBuffered property to True.
I would highly recommend if you plan on extending this to do your drawing to the PictureBox control. PictureBox is double-buffered by default and allows you to control your drawing region much more simply.
In code:
public partial class Form1 : Form
{
int xFirst, yFirst;
Bitmap bm = new Bitmap(1000, 1000);
Graphics bmG;
Pen pen = new Pen(Color.Black, 1);
bool draw = false;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
bmG = Graphics.FromImage(bm);
bmG.Clear(Color.White);
}
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
xFirst = e.X;
yFirst = e.Y;
draw = true;
}
private void Form1_MouseUp(object sender, MouseEventArgs e)
{
bmG.DrawLine(pen, xFirst, yFirst, e.X, e.Y);
draw = false;
Invalidate();
}
private void Form1_MouseMove(object sender, MouseEventArgs e)
{
if (draw)
{
Invalidate();
}
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
if (draw) {
e.Graphics.DrawImage(bm, 0, 0);
e.Graphics.DrawLine(pen, xFirst, yFirst, e.X, e.Y);
} else {
e.Graphics.DrawImage(bm, 0, 0);
}
}
}
Edit:
Another issue, you are creating a private Pen member. Pens (and Brushes, as well as many GDI+ objects) represent handles to unmanaged objects that need to be disposed otherwise your program will leak. Either wrap them in using statements (the preferred and exception-safe way) or explicitly dispose of them in the form's Dispose method.
Alternatively in System.Drawing you can access some pre-built Pens and Brushes that don't need to be (and shouldn't be) disposed. Use them like:
private void Form1_Paint(object sender, PaintEventArgs e)
{
if (draw) {
e.Graphics.DrawImage(bm, 0, 0);
e.Graphics.DrawLine(Pens.Black, xFirst, yFirst, e.X, e.Y);
} else {
e.Graphics.DrawImage(bm, 0, 0);
}
}

The reason it is flickering is that you are drawing the background (which is immediately displayed on screen, wiping away the line) and then superimpose the line. Thus the line keeps disappearing and appearing, giving a flickering display.
The best solution to this is called Double Buffering. What you do is draw the whole image to an "offscreen" bitmap, and only show it on the screen when it is completed. Because you only ever display the completed image, there is no flickering effect. You should just be able to set this.DoubleBuffered = true to get WinForms to do all the hard work for you.
NB: You shouldn't really be drawing outside of your paint handler - ideally, you should Invalidate() the area that needs redrawing, and then your paint handler will redraw just that area (with any overlaid lines etc as needed).

Fixed and working code.
public partial class Form1 : Form
{
int x1, y1, x2, y2;
bool drag = false;
Bitmap bm = new Bitmap(1000, 1000);
Graphics bmg;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
bmg = Graphics.FromImage(bm);
}
private void pictureBox_MouseDown(object sender, MouseEventArgs e)
{
drag = true;
x1 = e.X;
y1 = e.Y;
}
private void pictureBox_MouseUp(object sender, MouseEventArgs e)
{
drag = false;
bmg.DrawLine(Pens.Black, x1, y1, e.X, e.Y);
pictureBox.Invalidate();
}
private void pictureBox_MouseMove(object sender, MouseEventArgs e)
{
if (drag)
{
x2 = e.X;
y2 = e.Y;
pictureBox.Invalidate();
}
}
private void pictureBox_Paint(object sender, PaintEventArgs e)
{
if (drag) {
e.Graphics.DrawImage(bm, 0, 0);
e.Graphics.DrawLine(Pens.Black, x1, y1, x2, y2);
}
else {
e.Graphics.DrawImage(bm, 0, 0);
}
}
}

I Use this to manage the double buffering into a panel:
myPanel.GetType().GetMethod("SetStyle",
System.Reflection.BindingFlags.Instance |
System.Reflection.BindingFlags.NonPublic).Invoke(myPanel,
new object[]
{
System.Windows.Forms.ControlStyles.UserPaint |
System.Windows.Forms.ControlStyles.AllPaintingInWmPaint |
System.Windows.Forms.ControlStyles.DoubleBuffer, true
});