I have a c# windows form program where the user can draw lines with a mouse on an image in the picture box. The graphics are meant to be created by the pictureBox1_Paint method. How can I erase the drawn lines and keep the image in tact?
Defined default image here:
public lineTest()
{
InitializeComponent();
defaultImage = pictureBox1.Image;
}
Drew lines like this:
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
lines.Push(new Line { Start = e.Location });
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (lines.Count > 0 && e.Button == System.Windows.Forms.MouseButtons.Left)
{
lines.Peek().End = e.Location;
pictureBox1.Invalidate();
}
}
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
foreach (var line in lines)
{
Pen magenta = new Pen(Color.Magenta, 5);
e.Graphics.DrawLine(magenta, line.Start, line.End);
}
}
And tried erasing lines with:
private void button1_Click(object sender, EventArgs e)
{
pictureBox1.Image = defaultImage;
pictureBox1.Invalidate();
}
and nothing appears to happen.
Paint is called every time you invalidate the control so your lines are re-drawn every time. In your button1_Click event handler add this line:
lines.Clear();
before you call pictureBox1.Invalidate();
That will stop the lines being re-drawn when the paint event next fires.
Related
I have a paint event of form1.
private void Form1_Paint(object sender, PaintEventArgs e)
{
if (bmp != null)
e.Graphics.DrawImage(bmp, 0, 0,50,50);
}
And a form1 click event.
private void Form1_Click(object sender, EventArgs e)
{
// Cast to MouseEventArgs
MouseEventArgs mouse = (MouseEventArgs)e;
// If mouse is within image
if (mouse.X >= 0 && mouse.Y >= 0 && mouse.X < 0 + bmp.Width && mouse.Y < 0 + bmp.Height)
{
MessageBox.Show("hi");
}
}
But in this case when i click on the image at 0,0 it will show the messagebox but also if i click out of the image area.
I need that it will show the messagebox only if i clicked on the image area and borders. Even if i click on the edge of the image border it will show the messagebox and also if i click somewhere on the image it self. Anywhere out the image area won't display the messagebox.
You can try this out:
public partial class Form1 : Form
{
Rectangle rec;
Bitmap bmp;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
bmp = new Bitmap(#"YourImageUrlHere");
rec = new Rectangle(0, 0, 100, 100);
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
if (bmp != null)
e.Graphics.DrawImage(bmp, rec);
}
//private void Form1_Click(object sender, EventArgs e)
//{
// dont use this....
//}
private void Form1_MouseClick(object sender, MouseEventArgs e)
{
if(rec.Contains(e.Location))
MessageBox.Show("Test");
}
}
I have a custom PictureBox which can zoom in using MouseWheel event. Now I want to add a panning feature to it. I mean when PictureBox is in zoomed state, if user left clicks and holds the click then move the mouse, the image would pan within the picturebox.
Here is my code but unfortunately it does not work! I don't know where to look anymore...
private Point _panStartingPoint = Point.Empty;
private bool _panIsActive;
private void CurveBox_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
Focus();
_panIsActive = true;
_panStartingPoint = e.Location;
}
}
private void CurveBox_MouseUp(object sender, MouseEventArgs e)
{
_panIsActive = false;
}
private void CurveBox_MouseLeave(object sender, EventArgs e)
{
_panIsActive = false;
}
private void CurveBox_MouseMove(object sender, MouseEventArgs e)
{
if(_panIsActive && IsZoomed)
{
var g = CreateGraphics(); //Create graphics from PictureBox
var nx = _panStartingPoint.X + e.X;
var ny = _panStartingPoint.Y + e.Y;
var sourceRectangle = new Rectangle(nx, ny, Image.Width, Image.Height);
g.DrawImage(Image, nx, ny, sourceRectangle, GraphicsUnit.Pixel);
}
}
I am suspecting the MouseMove event...I am not sure if anything happens in this event and/or nx and ny does contain correct point.
Any helps/tips is really appriciated!
I think the math is backwards. Try it like this:
private Point startingPoint = Point.Empty;
private Point movingPoint = Point.Empty;
private bool panning = false;
void pictureBox1_MouseDown(object sender, MouseEventArgs e) {
panning = true;
startingPoint = new Point(e.Location.X - movingPoint.X,
e.Location.Y - movingPoint.Y);
}
void pictureBox1_MouseUp(object sender, MouseEventArgs e) {
panning = false;
}
void pictureBox1_MouseMove(object sender, MouseEventArgs e) {
if (panning) {
movingPoint = new Point(e.Location.X - startingPoint.X,
e.Location.Y - startingPoint.Y);
pictureBox1.Invalidate();
}
}
void pictureBox1_Paint(object sender, PaintEventArgs e) {
e.Graphics.Clear(Color.White);
e.Graphics.DrawImage(Image, movingPoint);
}
You aren't disposing your graphic object, and CreateGraphics is just a temporary drawing anyway (minimizing would erase it) so I moved the drawing code to the Paint event and am just invalidating as the user is panning.
I have a PictureBox that is inside a TabPage, and of course this TabPage is part of a TabView and this TabView is inside a Form. I want users be able to move this picture box within the tab page. For this I am using the MouseDown, MouseMove and MouseUp events of the picture box:
private void pictureBoxPackageView_MouseDown(object sender, MouseEventArgs e)
{
if (!_mapPackageIsMoving)
{
_mapPackageIsMoving = true;
}
}
private void pictureBoxPackageView_MouseMove(object sender, MouseEventArgs e)
{
if(_mapPackageIsMoving)
{
pictureBoxPackageView.Location = MousePosition; //This is not exact at all!
return;
}
//Some other code for some other stuff when picturebox is not moving...
}
private void pictureBoxPackageView_MouseUp(object sender, MouseEventArgs e)
{
if (_mapPackageIsMoving)
{
_mapPackageIsMoving = false; //Mouse button is up, end moving!
return;
}
}
But my problem lies in the MouseMove event. As soon as I move mouse after button down, the picture box jumps out of tab page's visible area.
I need to know how to handle the move only within the rectangle of the tab page, and if picture box is being dragged out of tab view's visible area, it shouldn't move anymore unless user brings the mouse inside the tab view's visible rectangle.
Any helps/tips will be appriciated!
You need a variable to hold the original position of the PictureBox:
Modified from a HansPassant answer:
private Point start = Point.Empty;
void pictureBoxPackageView_MouseUp(object sender, MouseEventArgs e) {
_mapPackageIsMoving = false;
}
void pictureBoxPackageView_MouseMove(object sender, MouseEventArgs e) {
if (_mapPackageIsMoving) {
pictureBoxPackageView.Location = new Point(
pictureBoxPackageView.Left + (e.X - start.X),
pictureBoxPackageView.Top + (e.Y - start.Y));
}
}
void pictureBoxPackageView_MouseDown(object sender, MouseEventArgs e) {
start = e.Location;
_mapPackageIsMoving = true;
}
I have a panel named dPanel. I set the the backgroundImage of that panel with an image named dImage.Now I want to draw points on the panel, in other words I want to color the panel by using mouse.I want to be able to save the drawing and the image together later. My codes do this but the picture lights up during drawing and its very slow.Here is my code:
private void drawP_MouseDown(object sender, MouseEventArgs e)
{
if (!drawbool)
{
dStartPoint = e.Location;
drawbool = true;
}
drawP.Invalidate();
}
private void drawP_MouseMove(object sender, MouseEventArgs e)
{
if (drawbool)
{
dStartPoint = e.Location;
drawP.Invalidate();
}
}
private void drawP_MouseUp(object sender, MouseEventArgs e)
{
if (drawbool)
{
drawbool = false;
}
}
private void drawP_Paint_1(object sender, PaintEventArgs e)
{
if (drawbool)
{
int dStartX = dStartPoint.X;
int dStartY = dStartPoint.Y;
e.Graphics.DrawEllipse(dP, dStartX, dStartY, 2, 2);
Bitmap dPPB = new Bitmap(drawP.Width, drawP.Height);
drawP.DrawToBitmap(dPPB, new Rectangle(0, 0, drawP.Width, drawP.Height));
drawP.BackgroundImage = (Image)dPPB;
}
}
Whani's the solution? Thanks in advance.
Check out this great example about drawing on panel: Painting on a Panel.
Later you can save your drawing just by invoking panel's method DrawToBitmap.
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