Develop Reference

How to make an image(or a rectangle) follow a Spline

I have a project that I need to make an image follow a spline.
I build the spline using Graphics.DrawCurve through an array of Points.
I'm trying to use PointAnimationUsingPath but I can't seem to get it to work. Apparently it doesn't work in C# with Windows form.
Can someone give me a light on how to do this?
Thank you All.
-----EDIT-----
Change to a WPF UserControl as recommend in comments.
Still need some help as the shape does not move exactly following the dots, below my code:
public partial class SplineBox : UserControl
{
Point[] finalPoint;
public SplineBox()
{
InitializeComponent();
}
public void MoveShape(Point[] _path)
{
// Create a NameScope for the page so that
// we can use Storyboards.
NameScope.SetNameScope(this, new NameScope());
// Create the EllipseGeometry to animate.
EllipseGeometry animatedEllipseGeometry =
new EllipseGeometry(new Point(10, 100), 15, 15);
// Register the EllipseGeometry's name with
// the page so that it can be targeted by a
// storyboard.
this.RegisterName("AnimatedEllipseGeometry", animatedEllipseGeometry);
// Create a Path element to display the geometry.
Path ellipsePath = new Path();
ellipsePath.Data = animatedEllipseGeometry;
ellipsePath.Fill = Brushes.Blue;
ellipsePath.Margin = new Thickness(15);
SplineCanvas.Children.Add(ellipsePath);
this.Content = SplineCanvas;
// Create the animation path.
PathGeometry animationPath = new PathGeometry();
PathFigure pFigure = new PathFigure();
pFigure.StartPoint = _path[0];
PolyBezierSegment pBezierSegment = new PolyBezierSegment();
for (int p = 1; p < _path.Length; p++)
{
pBezierSegment.Points.Add(_path[p]);
}
pFigure.Segments.Add(pBezierSegment);
animationPath.Figures.Add(pFigure);
// Freeze the PathGeometry for performance benefits.
animationPath.Freeze();
// Create a PointAnimationgUsingPath to move
// the EllipseGeometry along the animation path.
PointAnimationUsingPath centerPointAnimation = new PointAnimationUsingPath();
centerPointAnimation.PathGeometry = animationPath;
centerPointAnimation.Duration = TimeSpan.FromSeconds(5);
centerPointAnimation.RepeatBehavior = RepeatBehavior.Forever;
// Set the animation to target the Center property
// of the EllipseGeometry named "AnimatedEllipseGeometry".
Storyboard.SetTargetName(centerPointAnimation, "AnimatedEllipseGeometry");
Storyboard.SetTargetProperty(centerPointAnimation,
new PropertyPath(EllipseGeometry.CenterProperty));
// Create a Storyboard to contain and apply the animation.
Storyboard pathAnimationStoryboard = new Storyboard();
pathAnimationStoryboard.RepeatBehavior = RepeatBehavior.Forever;
pathAnimationStoryboard.AutoReverse = true;
pathAnimationStoryboard.Children.Add(centerPointAnimation);
// Start the Storyboard when ellipsePath is loaded.
ellipsePath.Loaded += delegate (object sender, RoutedEventArgs e)
{
// Start the storyboard.
pathAnimationStoryboard.Begin(this);
};
}
public void Paint(ScreenObject _spline)
{
List<Point> points = new List<Point>();
if (true)
{
var spline = _spline;
foreach (System.Windows.Point point in spline.SplineAnchors)
{
Point tempP = new Point((int)point.X, (int)point.Y);
points.Add(tempP);
}
finalPoint = points.ToArray();
//Pen pen = new Pen(Color.FromArgb(255, 0, 0, 255), 1);
//e.Graphics.DrawCurve(pen, finalPoint);
foreach (Point p in finalPoint)
{
// Create a red Ellipse.
Ellipse myEllipse = new Ellipse();
// Create a SolidColorBrush with a red color to fill the
// Ellipse with.
SolidColorBrush mySolidColorBrush = new SolidColorBrush();
// Describes the brush's color using RGB values.
// Each value has a range of 0-255.
mySolidColorBrush.Color = Color.FromArgb(255, 100, 255, 0);
myEllipse.Fill = mySolidColorBrush;
myEllipse.StrokeThickness = 2;
myEllipse.Stroke = Brushes.Black;
// Set the width and height of the Ellipse.
myEllipse.Width = 10;
myEllipse.Height = 10;
myEllipse.Margin = new Thickness(p.X - 5, p.Y - 5, 0, 0);
//e.Graphics.DrawRectangle(pen, new Rectangle(p.X - 5, p.Y - 5, 10, 10));
//e.Graphics.FillRectangle(Brushes.Red, new Rectangle(p.X - 5, p.Y - 5, 10, 10));
SplineCanvas.Children.Add(myEllipse);
}
}
}
}

Draw circle in new position without removing previous circle?

In fact , I want to draw circle in new position each time double-click and without remove before circle ,It should be noted that, I used PictureBox.
public Point postionCursor { get; set; }
List<Point> points = new List<Point>();
private void pictureBox1_DoubleClick(object sender, EventArgs e)
{
postionCursor = this.PointToClient(new Point(Cursor.Position.X - 25, Cursor.Position.Y - 25));
points.Add(postionCursor);
pictureBox1.Invalidate();
pictureBox1.Paint += new PaintEventHandler(pic_Paint);
}
private void pic_Paint(object sender, PaintEventArgs e)
{
Graphics g = e.Graphics;
g.SmoothingMode = SmoothingMode.AntiAlias;
foreach (Point pt in points)
{
Pen p = new Pen(Color.Tomato, 2);
SolidBrush myb = new SolidBrush(Color.White);
g.DrawEllipse(p, postionCursor.X, postionCursor.Y, 20, 20);
g.FillEllipse(myb, postionCursor.X, postionCursor.Y, 20, 20);
p.Dispose();
}
}

You're not using the pt variable in the foreach loop.
foreach (Point pt in points)
{
using(Pen p = new Pen(Color.Tomato, 2))
using(SolidBrush myb = new SolidBrush(Color.White))
{
g.FillEllipse(myb, pt.X, pt.Y, 20, 20);
g.DrawEllipse(p, pt.X, pt.Y, 20, 20);
}
}
In your code, you were just overwriting the circle in the same location for every Point in the points list.
Also, as Reza mentioned in the comments, you don't need to attach the PaintEventHandler event hanlder every time the PictureBox is clicked, you just need to do it once.

So I got to thinking, and then Visual Studio-ing, that perhaps we don't even need the foreach loop. I still maintain a List so we know where the user has clicked, but there's no need to loop through it and redraw everything every time.
I realize this doesn't handle the case where the underlying list is modified, but nor does the original sample. Here's my entire Form1 class:
public partial class Form1 : Form
{
private const int CircleDiameter = 20;
private const int PenWidth = 2;
private readonly List<Point> _points = new List<Point>();
public Form1()
{
InitializeComponent();
pictureBox1.Paint += (sender, args) =>
{
_points.ForEach(p => DrawPoint(p, args.Graphics));
};
}
private void pictureBox1_DoubleClick(object sender, EventArgs e)
{
var cursorLocation = pictureBox1.PointToClient(Cursor.Position);
_points.Add(cursorLocation);
var circleArea = new Rectangle(
cursorLocation.X - CircleDiameter/2 - PenWidth,
cursorLocation.Y - CircleDiameter/2 - PenWidth,
CircleDiameter + PenWidth*2,
CircleDiameter + PenWidth*2);
pictureBox1.Invalidate(circleArea);
}
private static void DrawPoint(Point point, Graphics graphics)
{
point.X -= CircleDiameter / 2;
point.Y -= CircleDiameter / 2;
using (var pen = new Pen(Color.Tomato, PenWidth))
using (var brush = new SolidBrush(Color.White))
{
graphics.SmoothingMode = SmoothingMode.AntiAlias;
graphics.DrawEllipse(pen, point.X, point.Y, CircleDiameter, CircleDiameter);
graphics.FillEllipse(brush, point.X, point.Y, CircleDiameter, CircleDiameter);
}
}
}
Update 1:
So I updated the code to use the Paint event which has the foreach loop. However, I don't Invalidate (and Paint) every time a circle is added - there's no need for that. Just adding a circle by drawing means the control only invalidates and re-paints the region where the new circle was added.
Try setting a breakpoint on the DrawAllPoints method. You'll see it only happens during full invalidation operations such as minimizing and restoring.
Update 2:
After further chat, I agree the Invalidate method is superior. Code updated to use Invalidate with a rectangle to invalidate.
And now it's looking very much like the OP :)

How can I make a graphics path with more points?

I'm creating a path that will be followed by a rectangle. I want to make it with more "tick" points, since on each timer tick I draw it on the next point on the made curve. When it reaches the curve's turn, it goes smoothly, since there are more points at the curve, but at the straight parts of the path, it skips a lot of distance to reach the next points on the list. How can I make the PathPoints with more points? Or is there a better approach to what I'm trying to do? The approach that I'm using, I found it on the internet.
public Form1()
{
InitializeComponent();
//avoid flickering
this.DoubleBuffered = true;
//make a bitmap to display
_bmp = new Bitmap(100, 100);
using (Graphics g = Graphics.FromImage(_bmp))
{
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
g.FillRectangle(Brushes.Aquamarine, new Rectangle(_bmp.Width / 2 - 2, _bmp.Height / 2 - 2, 10, 10));
}
//cleanup
this.FormClosing += delegate { if (_bmp != null) _bmp.Dispose(); if (_gPath != null) _gPath.Dispose(); };
//setup a path and add some random values
_gPath = new System.Drawing.Drawing2D.GraphicsPath();
List<Point> fList = new List<Point>();
//add points that will let the picturebox be fully visible inside the form
Point middle = new Point(this.ClientSize.Width / 2, this.ClientSize.Height / 2);
fList.Add(new Point(this.ClientSize.Width / 2, this.ClientSize.Height));
fList.Add(new Point(middle.X - 20, middle.Y + 20));
fList.Add(new Point(0, this.ClientSize.Height / 2));
//fList.Add(new Point(this.ClientSize.Width / 2, this.ClientSize.Height / 2));
//add a curve by these values
_gPath.AddCurve(fList.ToArray());
//flatten, to make the path a Path of lines and points
_gPath.Flatten();
//get these points as Array to locate the picturebox
this._points = _gPath.PathPoints;
//add the handler for the paint-event
this.Paint += new PaintEventHandler(Form1_Paint);
//start the timer
t.Tick += new EventHandler(t_Tick);
t.Interval = 100;
t.Start();
Console.WriteLine(_points.Length);
}
void Form1_Paint(object sender, PaintEventArgs e)
{
if (_gPath != null && _bmp != null)
{
//draw the image
e.Graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
e.Graphics.DrawPath(Pens.Black, _gPath);
e.Graphics.DrawImage(_bmp, (int)_points[_i].X - (_bmp.Width / 2), (int)_points[_i].Y - (_bmp.Height / 2));
}
}
void t_Tick(object sender, EventArgs e)
{
t.Stop();
//redraw
this.Invalidate();
_i++;
if (_i >= _points.Length)
_i = 0;
t.Start();
}
}

To make more points you should overload for Flatten method:
_gPath.Flatten(null, (float) 0.1);
Also I would recommend to organize Animation loop to have interval of 40ms. So it would be 25 frames per second. (1000s / 25 = 40 ms)
t.Interval = 40;

Draw line in picturebox and redraw on zoom

I'm drawing a line in a picturebox this way:
horizontalstart = new Point(0, e.Y); //Start point of Horizontal line.
horizontalend = new Point(picbox_mpr.Width, e.Y); //End point of Horizontal line.
verticalstart = new Point(e.X, 0); //Start point of Vertical line
verticalend = new Point(e.X, picbox_mpr.Height); //End point of Vertical line.
Then on the paint event I do this:
e.Graphics.DrawLine(redline, horizontalstart, horizontalend); //Draw Horizontal line.
e.Graphics.DrawLine(redline, verticalstart, verticalend); //Draw Vertical line.
Pretty simple, now, my image can zoom and here's where I struggle..
How do I keep the line in the same spot that was drawn even if I zoom the image?

Instead of storing an absolute integer coordinate, store a decimal value representing the "percentage" of that coord with respect to the width/height of the image. So if the X value was 10 and the width was 100, you store 0.1. Let's say the image was zoomed and it was now 300 wide. The 0.1 would now translate to 0.1 * 300 = 30. You can store the "percentage" X,Y pairs in PointF() instead of Point().
Here's a quick example to play with:
public partial class Form1 : Form
{
private List<Tuple<PointF, PointF>> Points = new List<Tuple<PointF, PointF>>();
public Form1()
{
InitializeComponent();
this.Shown += new EventHandler(Form1_Shown);
this.pictureBox1.BackColor = Color.Red;
this.pictureBox1.SizeChanged += new EventHandler(pictureBox1_SizeChanged);
this.pictureBox1.Paint += new PaintEventHandler(pictureBox1_Paint);
}
void Form1_Shown(object sender, EventArgs e)
{
// convert absolute points:
Point ptStart = new Point(100, 25);
Point ptEnd = new Point(300, 75);
// to percentages:
PointF ptFstart = new PointF((float)ptStart.X / (float)pictureBox1.Width, (float)ptStart.Y / (float)pictureBox1.Height);
PointF ptFend = new PointF((float)ptEnd.X / (float)pictureBox1.Width, (float)ptEnd.Y / (float)pictureBox1.Height);
// add the percentage point to our list:
Points.Add(new Tuple<PointF, PointF>(ptFstart, ptFend));
pictureBox1.Refresh();
}
private void button1_Click(object sender, EventArgs e)
{
// increase the size of the picturebox
// watch how the line(s) change with the changed picturebox
pictureBox1.Size = new Size(pictureBox1.Width + 50, pictureBox1.Height + 50);
}
void pictureBox1_SizeChanged(object sender, EventArgs e)
{
pictureBox1.Refresh();
}
void pictureBox1_Paint(object sender, PaintEventArgs e)
{
foreach (Tuple<PointF, PointF> tup in Points)
{
// convert the percentages back to absolute coord based on the current size:
Point ptStart = new Point((int)(tup.Item1.X * pictureBox1.Width), (int)(tup.Item1.Y * pictureBox1.Height));
Point ptEnd = new Point((int)(tup.Item2.X * pictureBox1.Width), (int)(tup.Item2.Y * pictureBox1.Height));
e.Graphics.DrawLine(Pens.Black, ptStart, ptEnd);
}
}
}

Crosshair cursor with additional lines in C#

how to make a crosshair cursor with help lines like this on screenshots:
I know how to make crosshire cursor:
this.Cursor = System.Windows.Forms.Cursors.Cross;
can be also something like that:
like in CAD software.

This is the code I use. x and y are the dimensions. In my case I can have some text on the cursor and this is name. If you want dots or dashes then you need to do that with the pen.
private Cursor crossCursor(Pen pen, Brush brush, string name, int x, int y) {
var pic = new Bitmap(x, y);
Graphics gr = Graphics.FromImage(pic);
var pathX = new GraphicsPath();
var pathY = new GraphicsPath();
pathX.AddLine(0, y / 2, x, y / 2);
pathY.AddLine(x / 2, 0, x / 2, y);
gr.DrawPath(pen, pathX);
gr.DrawPath(pen, pathY);
gr.DrawString(name, Font, brush, x / 2 + 5, y - 35);
IntPtr ptr = pic.GetHicon();
var c = new Cursor(ptr);
return c;
}

Just create two label box as lab_X_Axis and lab_Y_Axis.
In chart mousemove function code as shown below..
private void chart1_MouseMove(object sender, MouseEventArgs e)
{
lab_X_Axis.Location = new Point((e.X), 21);
lab_Y_Axis.Location = new Point(76, e.Y);
}
private void Form1_Load(object sender, EventArgs e)
{
lab_X_Axis.AutoSize = false;
lab_Y_Axis.AutoSize = false;
lab_X_Axis.Text="";
lab_Y_Axis.Text="";
lab_X_Axes.Size = new Size(1, 300);
lab_Y_Axes.Size = new Size(300, 1);
}