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Why can't it draw a rectangle the opposite way?

So I am trying to recreate the Snipping Tool that comes with Windows.
However I've manage to get it to draw a rectangle from the top left corner and then when I move my cursor to the bottom right.
However if I try to move my cursor from let's say the middle of the screen to the top left it doesnt draw the rectangle.
Why is this?
Here is a GIF showing what happends
https://i.imgur.com/0Y7xXnS.gifv
//These variables control the mouse position
int selectX;
int selectY;
int selectWidth;
int selectHeight;
public Pen selectPen;
//This variable control when you start the right click
bool start;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
//Hide the Form
this.Hide();
//Create the Bitmap (This is an a black bitmap holding just the size.) (Bitmap is mutable)
Bitmap printscreen = new Bitmap(Screen.PrimaryScreen.Bounds.Width,
Screen.PrimaryScreen.Bounds.Height);
//Create a graphics object that's ready for alteration. `printscreen` is now a graphics Object
Graphics graphics = Graphics.FromImage(printscreen);
//Alter the graphics object which again is the printscreen
graphics.CopyFromScreen(0, 0, 0, 0, printscreen.Size);
//Create a temporary memory stream for the image
using (MemoryStream s = new MemoryStream())
{
//save graphic variable into memory
printscreen.Save(s, ImageFormat.Bmp);
//Set the size of the picturebox
pictureBox1.Size = new Size(Width, Height);
//set the value of the picturebox.Image to an Image.FromStream and load the temp stream
pictureBox1.Image = Image.FromStream(s);
}
//Show Form
this.Show();
//Cross Cursor
Cursor = Cursors.Cross;
}
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
selectX = e.X;
selectY = e.Y;
selectPen = new Pen(Color.DimGray, 1);
selectPen.DashStyle = DashStyle.Solid;
pictureBox1.Refresh();
start = true;
}
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (start)
{
selectWidth = e.X - selectX;
selectHeight = e.Y - selectY;
pictureBox1.Refresh();
pictureBox1.CreateGraphics().DrawRectangle(selectPen,
selectX, selectY, selectWidth, selectHeight);
}
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
Stream sound = Resources.SnapshotSound;
SoundPlayer player = new SoundPlayer(sound);
player.PlaySync();
Application.Exit();
}
}

So what you end up with is basically a rectangle with a negative width and height.
You'll probably want to use the Math.Abs to make sure you get a proper width and height in the cases the difference would become negative.
With that, you will also probably want to draw from different positions based on where your cursor is in relation to the selected point. Something like
selectWidth = e.X - selectX;
selectHeight = e.Y - selectY;
// If width is less than 0, draw from pointer, otherwise from select X
var drawFromX = selectWidth < 0 ? e.X : selectX;
// If height is less than 0, draw from pointer, otherwise from select Y
var drawFromY = selectHeight < 0 ? e.Y : selectY;
pictureBox1.Refresh();
pictureBox1.CreateGraphics().DrawRectangle(selectPen,
drawFromX,
drawFromY,
Math.Abs(selectWidth), // Make sure the rectangle width is positive
Math.Abs(selectHeight)); // Make sure the rectangle height is positive

C# ImageBox Clear Rectangle on MouseUp

I have a panel with multiple picturebox created at runtime.
The user will create a rectangle on any picture box and the selected part will be displayed on a preview picturebox.
I have successfully done the above using the below code.
Question
I want to clear the selection rectangle at mouseup event. Used invalidate but not working.
From how to clear the graphics(rectangle shape) in picturebox
Also, when I scroll the panel the same rectangle(mouse selection) is shown on all picturebox.
private void Picture_Paint(object sender, PaintEventArgs e)
{
if (Rect!=null && Rect.Width>0 && Rect.Height>0)
{
e.Graphics.FillRectangle(selectionBrush, Rect);
}
}
private void Picture_MouseDown(object sender, MouseEventArgs e)
{
RecStartpoint = e.Location;
((PictureBox)sender).Invalidate();
}
private void Picture_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button != MouseButtons.Left) return;
Point tempEndPoint = e.Location;
Rect.Location = new Point(
Math.Min(RecStartpoint.X, tempEndPoint.X),
Math.Min(RecStartpoint.Y, tempEndPoint.Y));
Rect.Size = new Size(
Math.Abs(RecStartpoint.X - tempEndPoint.X),
Math.Abs(RecStartpoint.Y - tempEndPoint.Y));
((PictureBox)sender).Invalidate();
}
private void Picture_MouseUp(object sender, MouseEventArgs e)
{
if (e.Button != MouseButtons.Left) return;
PictureBox org_pic = (PictureBox)(sender);
Point RecEndpoint=e.Location;
int xDown = Math.Min(RecStartpoint.X,RecEndpoint.X);
int yDown = Math.Min(RecStartpoint.Y, RecEndpoint.Y);
int xUp = Math.Max(RecStartpoint.X,RecEndpoint.X);
int yUp = Math.Max(RecStartpoint.Y,RecEndpoint.Y);
Rectangle rec = new Rectangle(xDown, yDown, Math.Abs(xUp - xDown), Math.Abs(yUp - yDown));
xDown = xDown * org_pic.Image.Width / org_pic.Width;
yDown = yDown * org_pic.Image.Height / org_pic.Height;
xUp = xUp * org_pic.Image.Width / org_pic.Width;
yUp = yUp * org_pic.Image.Height / org_pic.Height;
rectCropArea = new Rectangle(xDown, yDown, Math.Abs(xUp - xDown), Math.Abs(yUp - yDown));
pictureBox_preview_photo.Refresh();
Bitmap sourceBitmap = new Bitmap(org_pic.ImageLocation);
Graphics g = pictureBox_preview_photo.CreateGraphics();
g.DrawImage(sourceBitmap, new Rectangle(0, 0, pictureBox_preview_photo.Width, pictureBox_preview_photo.Height), rectCropArea, GraphicsUnit.Pixel);
}

I would try this approach:
First, make Image variable, in the scope of form
public partial class Form1 : Form
{
//variable for holding original image, before rectangle is drawn on it
Image originalImage = null;
public Form1()
{
InitializeComponent();
}
//rest of form's code...
second, save current picture in that variable on MouseDown
private void Picture_MouseDown(object sender, MouseEventArgs e)
{
//save it
startImage = ((PictureBox)sender).Image;
RecStartpoint = e.Location;
((PictureBox)sender).Invalidate();
}
lastly, on the end of MouseUp event, set Rectangle's width and height to zero and restore saved, original image
//snipped code
pictureBox_preview_photo.Refresh();
Bitmap sourceBitmap = new Bitmap(org_pic.ImageLocation);
Graphics g = pictureBox_preview_photo.CreateGraphics();
g.DrawImage(sourceBitmap, new Rectangle(0, 0, pictureBox_preview_photo.Width, pictureBox_preview_photo.Height), rectCropArea, GraphicsUnit.Pixel);
//make rectangle's widht and height 0 so that Paint event won't draw it
Rect.Width = Rect.Height = 0;
//restore image
this.Picture.Image = startImage;
I didn't understand that second question.

I'm trying to show the current image in the pictureBox and stretch it but it's not showing anything why?

In For1 i have this code:
private void timer1_Tick(object sender, EventArgs e)
{
try
{
this.pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
pictureBox1.Load(file_array_satellite[file_indxs_satellite]);
file_indxs_satellite = file_indxs_satellite - 1;
if (file_indxs_satellite < 0)
{
file_indxs_satellite = file_array_satellite.Length - 1;
}
}
catch
{
timer1.Enabled = false;
}
}
private void satellitesToolStripMenuItem_Click(object sender, EventArgs e)
{
file_array_satellite = Directory.GetFiles(UrlsPath, "RainImage*.*");
if (file_array_satellite.Length > 0)
{
DateTime[] creationTimes8 = new DateTime[file_array_satellite.Length];
for (int i = 0; i < file_array_satellite.Length; i++)
creationTimes8[i] = new FileInfo(file_array_satellite[i]).CreationTime;
Array.Sort(creationTimes8, file_array_satellite);
file_indxs_satellite = 0;
file_indxs_satellite = file_array_satellite.Length - 1;
timer1.Enabled = true;
}
}
private void pictureBox1_MouseEnter(object sender, EventArgs e)
{
this.pictureBox1.Size = new Size(500, 500);
pictureBox1.Location = new Point(this.Bounds.Width / 2,
this.Bounds.Height / 2);
this.pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
pictureBox1.BringToFront();
}
private void pictureBox1_MouseLeave(object sender, EventArgs e)
{
this.pictureBox1.Size = new Size(100, 100);
pictureBox1.Location = new Point(12,
27);
}
In the original the picturebox1 size is 100x100 and each image i stretch to fit in the pictureBox.
When it's 100x100 everything is ok i see the animation of each image in the pictureBox.
Now i did an event that when i enter with the mouse to the pictureBox area it should move to the center of the form resize to 500x500 stretch the images and show the same animation.
And when i leave the pictureBox area it should return to it's original size and location.
When i enter with the mouse to the pictureBox1 area the pictureBox just vanish i don't see it anywhere once i leave the pictureBox area i see it 100x100 in it's original place and size.
Why when i enter with the mouse to the pictureBox1 area it's vanish i don't see it in the center of the form on size 500x500 ?
file_array_satellite is string[] and file_indxs_satellite is int.
RainImage*.* are the files names on the hard disk after downloaded them.
The idea is not to convert/change the files sizes on the hard disk each time i enter or leave so i wanted that once i enter the pictureBox1 area it will stretch the current image in the pictureBox and show it . It's working when it's 100x100 but not on 500x500.

When you mouse over the PictureBox and move it to the center of the form, you are moving it out from under the mouse cursor. This causes the MouseLeave event to immediately trigger, which places it back under your mouse cursor again, which causes the MouseEnter event to trigger again, etc.
You can do something like this:
bool suppressMouseLeave;
private void pictureBox1_MouseEnter(object sender, EventArgs e)
{
suppressMouseLeave = true;
this.pictureBox1.Size = new Size(500, 500);
pictureBox1.Location = new Point(this.Bounds.Width / 2,
this.Bounds.Height / 2);
this.pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
pictureBox1.BringToFront();
//point the cursor to the new Position so that it's still kept on the pictureBox1
//This is important because it makes your idea acceptable.
//Otherwise you have to move your mouse onto your pictureBox and leave the
//mouse from it then to restore the pictureBox
Cursor.Position = PointToScreen(new Point(pictureBox1.Left + 250, pictureBox1.Top + 250));
suppressMouseLeave = false;
}
private void pictureBox1_MouseLeave(object sender, EventArgs e)
{
if(suppressMouseLeave) return;
this.pictureBox1.Size = new Size(100, 100);
pictureBox1.Location = new Point(12, 27);
}

I would venture a guess that this.Bounds.Width and this.Bounds.Height are not what you expect them to be, so the PictureBox isn't vanishing, you are just setting it to some location that is offscreen/off your form. Run Visual Studio in Debug mode and put a breakpoint around that line and see what this.Bounds is equal to. This may give you a clue as to the proper location you need to set.

How about in "in place" zoom like this?
private void pictureBox1_MouseEnter(object sender, EventArgs e)
{
Rectangle rc = pictureBox1.Bounds;
rc.Inflate(200, 200);
pictureBox1.Bounds = rc;
pictureBox1.BringToFront();
}
private void pictureBox1_MouseLeave(object sender, EventArgs e)
{
Rectangle rc = pictureBox1.Bounds;
rc.Inflate(-200, -200);
pictureBox1.Bounds = rc;
}

Panel and ScrollBar in Windows forms

I am using a panel to display a image in windows forms
I am drawing image in the panel in Panel_Paint event as follows:
Graphics g = panel1.CreateGraphics();
Image im = new Bitmap(#"../../Data/#3_Page2.PNG");
g.DrawImage(im,new Point(10,10));
Now, the image is drawn as i expected, with some part of the bottom of the image not displaying as its height is greater than forms height.
I have added the VScrollBar now. How do i make that panel to view the rest of the image with the help of VScrollBar.

You can use PictureBox with SizeMode set to AutoSize and AutoScroll property of Panel. That way the panel should add scrollbars if they are needed.
PictureBox pictureBox = new System.Windows.Forms.PictureBox();
pictureBox.Image = new Bitmap(#"../../Data/#3_Page2.PNG");
pictureBox.SizeMode = System.Windows.Forms.PictureBoxSizeMode.AutoSize;
panel.AutoScroll = true;
panel.Controls.Add(this.pictureBox);

This solution works, however if your image is large enough, there is a little flicker when you scroll (however it's acceptable). First you have to add a VScrollBar right on the right of your panel and a HScrollBar right under the bottom of your panel. This demo requires you have a VScrollBar named vScrollBar1 and HScrollBar named hScrollBar1, a Button named buttonOpenImage to allow user to open some image, a Panel named panel1 used as the main area to draw the image:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
//To prevent/eliminate flicker, do this
typeof(Panel).GetProperty("DoubleBuffered",
System.Reflection.BindingFlags.Instance |
System.Reflection.BindingFlags.NonPublic).SetValue(panel1, true, null);
//------------------------
UpdateScrollbarsState();
}
int imgWidth, imgHeight;
Image image;
Point leftTop = Point.Empty;
int lastV, lastH;
private void OpenImage(){
OpenFileDialog openFile = new OpenFileDialog();
openFile.FileOk += (s, e) => {
try {
image = Image.FromFile(openFile.FileName);
//calculate the physical size of the image based on the resolution and its logical size.
//We have to do this because the DrawImage is based on the physical size (not logical).
imgWidth = (int)(image.Width * 96f / image.HorizontalResolution + 0.5);
imgHeight = (int)(image.Height * 96f / image.VerticalResolution + 0.5);
lastV = lastH = 0;
UpdateScrollbarsState();
vScrollBar1.Value = 0;
hScrollBar1.Value = 0;
panel1.Invalidate();
}
catch {
image = null;
MessageBox.Show("Image file is invalid or corrupted!");
}
};
openFile.ShowDialog();
}
private void UpdateScrollbarsState() {
//We have to update all the info about Minimum and Maximum
vScrollBar1.Minimum = 0;
hScrollBar1.Minimum = 0;
vScrollBar1.Maximum = Math.Max(imgHeight-panel1.Height,0);
hScrollBar1.Maximum = Math.Max(imgWidth-panel1.Width,0);
vScrollBar1.Visible = vScrollBar1.Maximum > 0;
hScrollBar1.Visible = hScrollBar1.Maximum > 0;
if (vScrollBar1.Maximum == 0) {
leftTop.Y = 0;
lastV = 0;
}
if (hScrollBar1.Maximum == 0) {
leftTop.X = 0;
lastH = 0;
}
}
private void panel1_Paint(object sender, PaintEventArgs e) {
if (image == null) return;
e.Graphics.DrawImage(image, leftTop);
}
//The ValueChanged event handler of your vScrollBar1
private void vScrollBar1_ValueChanged(object sender, EventArgs e) {
if (!vScrollBar1.Visible) return;
leftTop.Offset(0, -vScrollBar1.Value + lastV);
lastV = vScrollBar1.Value;
panel1.Invalidate();
}
//The ValueChanged event handler of your hScrollBar1
private void hScrollBar1_ValueChanged(object sender, EventArgs e) {
if (!hScrollBar1.Visible) return;
leftTop.Offset(lastH - hScrollBar1.Value, 0);
lastH = hScrollBar1.Value;
panel1.Invalidate();
}
//handler for SizeChanged event of the panel. However if resizing
//the form causes the panel's size changing, you should attach this
//handler for form.
private void panel1_SizeChanged(object sender, EventArgs e) {
UpdateScrollbarsState();
}
//handler for the Click event of a button (click to open an image)
private void buttonOpenImage_Click(object sender, EventArgs e) {
OpenImage();
}
}

How do i insert a Box which i drew out from pen to a picturebox image?

i need help on inserting a box which i drew out from into a picturebox.
here is the code of the pen that i code out, i do not know how to put it in the picturebox.
there will be a webcam running on the background of the picturebox, i want my rectangle to be inside the picturebox.
private void button1_Click(object sender, EventArgs e)
{
if (button1.Text == "Start")
{
Graphics myGraphics = base.CreateGraphics();
myGraphics.Clear(Color.White);
Pen myPen = new Pen(Color.DarkBlue);
Rectangle rect = new Rectangle(480, 70, 120, 120);
myGraphics.DrawRectangle(myPen, rect);
stopWebcam = false;
button1.Text = "Stop";
}
else
{
stopWebcam = true;
button1.Text = "Start";
}
}

Paining in winforms is primarily done in the OnPaint event. Your ButtonClick event handler should only setup the stage for OnPaint and possibly activate it. Example:
public class MyForm : Form
...
private Rectangle? _boxRectangle;
private void OnMyButtonClick(object sender, EventArgs e)
{
if (button1.Text == "Start")
{
_boxRectangle = new Rectangle(...);
button1.Text = "Stop";
}
else
{
_boxRectangle = null;
button1.Text = "Start";
}
Invalidate(); // repaint
}
protected override OnPaint(PaintEventArgs e)
{
if (_boxRectangle != null)
{
Graphics g = e.Graphics.
Pen pen = new Pen(Color.DarkBlue);
g.DrawRectangle(_boxRectangle);
}
}
}

You may have to draw the web cam image onto a bitmap buffer and use that as an image for the picture box.
Here is the msdn page with examples at the bottom:
http://msdn.microsoft.com/en-us/library/system.windows.forms.picturebox.aspx
Here is my method for doing it.
public void GraphicsToPictureBox (ref PictureBox pb, Graphics graphics,
Int32 width, Int32 height)
{
Bitmap bitmap = new Bitmap(width,height,graphics);
pb.Image = bitmap;
}