When i'm trying to draw a rectangle in PictureBox with negative coordinates (-x and -y) the rectangle dissapears, though when it has positive coordinates everything is okay. Here's the code:
Here I get starting coordinates of rectangle
private void PictureBox1_MouseDown(object sender, MouseEventArgs e)
{
start_point.X = e.X;
start_point.Y = e.Y;
}
Here I get the ending coordinates of rectangle:
private void PictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
end_point.X = e.X;
end_point.Y = e.Y;
PictureBox1.Refresh();
}
}
Here I calculate the rectangles width and height:
private void PictureBox1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.FillRectangle(sb, start_point.X, start_point.Y, end_point.X - start_point.X, end_point.Y - start_point.Y);
}
If the starting point coordinates are smaller than ending ones, everything works just fine, but when the ending coordinates are smaller than starting ones, the width or height or both values are negative...
How can I solve this problem?
There are 4 possible ways for the user to drag the mouse to make the rectangle. Only one of them you're happy with right now, from upper-left to lower-right. The other 3 ways produce negative values for the rectangle's Width or Height. You deal with all 4 possibilities like this:
var rc = new Rectangle(
Math.Min(startpoint.x, endpoint.x),
Math.Min(startpoint.y, endpoint.y),
Math.Abs(endpoint.x - startpoint.x),
Math.Abs(endpoint.y - startpoint.y));
e.Graphics.FillRectangle(sb, rc);
If the starting X is < the ending X, just swap the values before drawing. Same for the Y coordinates.
if ( start_point.X < end_point.X )
{
var oldX = start_point.X;
start_point.X = end_point.X;
end_point.X = oldX;
}
if ( start_point.Y < end_point.Y )
{
var oldY = start_point.Y;
start_point.Y = end_point.Y;
end_point.Y = oldY;
}
Related
I have a jpeg image in a picturebox, on page load i am drawing the rectangle based on the x(150) and y(440) coordinates. now when i mousemove on the picturebox i need to identify the rectangle by their coordinates and highlight the image. for example see the below image ..
lets take the first rectangle, on mouse move any points inside the rectangle i need to perform some actions.. how to find the coordinates between these x and y for the rectangle?..
A rectangle has 4 Points (edges):
Left
Top
Right
Bottom
If your mouse coordinates (MouseEventArgs properties) are between them, the mouse pointer is in the rectangle.
Are the mouse coordinates greater than right or bottom or lower than left / top, your mouse is outside the rectangle.
Taking #samgak`s Comment:
if(
(point.x >= rectangle.min_x) && (point.x <= rectangle.max_x) &&
(point.y >= rectangle.min_y) && (point.y <= rectangle.max_y)) {
//do something
}
and replacing point with e is exactly what you want.
Maybe the following link will help to understand:
How to check if a point is inside a rectangle
Provided images are the same size and assuming it is stored in variable imageSize (of type System.Drawing.Size) then:
Size imageSize = new Size(...) // define the size here
...
int row = point.y / imageSize.height;
int col = point.x / imageSize.width;
var rect = new Rectangle(col * imageSize.Width, row * imageSize.Height, imageSize.Width, imageSize.Height);
You can then use rect to draw you frame around the image (you may want to inflate the rectangle by a couple of pixels)
Hi Samgak /Clijsters,
I have completed my functionality
// page level declaration
private Rectangle SelectedRect;
public List<Rectangle> listRec = new List<Rectangle>();
// on page load add all the rectangle in the rectanglelist.
private void Highlightimage_Load(object sender, EventArgs e)
{
for (int i = 0; i < table.Rows.Count; i++)
{
int x = Convert.ToInt32(table.Rows[i][0]);
int y = Convert.ToInt32(table.Rows[i][1]);
int width = Convert.ToInt32(table.Rows[i][2]);
int height = Convert.ToInt32(table.Rows[i][3]);
SelectedRect.Size = new Size(width, height);
SelectedRect.X = x;
SelectedRect.Y = y;
listRec.Add(SelectedRect);
}
}
// draw the rectangle
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{ Graphics g = e.Graphics;
foreach (Rectangle rec in listRec)
{
Pen p = new Pen(Color.Red);
g.DrawRectangle(p, rec);
}
}
private Rectangle MakeRectangle(int x0, int y0, int x1, int y1)
{
return new Rectangle(
Math.Min(x0, x1),
Math.Min(y0, y1),
Math.Abs(x0 - x1),
Math.Abs(y0 - y1));
}
//finally on mouse move checking the condition
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
foreach (Rectangle rec in listRec)
{
SelectedRect = MakeRectangle(rec.Left, rec.Top, rec.Right, rec.Bottom);
if (
(e.X >= SelectedRect.Left) && (e.X <= SelectedRect.Right) &&
(e.Y >= SelectedRect.Top) && (e.Y <= SelectedRect.Bottom))
{
MessageBox.Show("test");
}
}
}
Also refered this link
Drawing Multiple Rectangles c#
I thought this will help some one.
Thanks
Dev
I have a Windows form application. When I press Draw button in it, it draws a line:
private void button1_Click(object sender, EventArgs e)
{
projectilePathPen = new Pen(Color.Black, 2);
projectilePathGraphics.DrawLine(projectilePathPen, 150, 150, 450, 150);
}
I have a Mouse Move event for the form (to get current mouse's coordinates):
private void panel1_MouseMove(object sender, MouseEventArgs e)
{
this.Cursor = Cursors.Cross;
int actualX, actualY;
actualX = Cursor.Position.X - 150;
actualY = 150 - Cursor.Position.Y;
labelX.Text = "Actual X: " +actualX.ToString();
labelY.Text = "Actual Y: " + actualY.ToString();
}
Whenerever I place this cursor, its giving me wrong values. I have placed it on the start of the line just drew and it's not giving (0,0) as predictably as it should be.
Replace these lines:
actualX = Cursor.Position.X - 150;
actualY = 150 - Cursor.Position.Y;
with these:
actualX = e.X - 150;
actualY = 150 - e.Y;
e.X and e.Y give you the local position of the cursor relative to your panel1 while Cursor.Postion is the global position of the cursor on the screen.
I need to move a rectangle using angles. Actually I want to change the direction of my moving rectangle when it reaches the location I have given in my code in if statement!
I just need the way I can find out how to move my rectangle at 60, 30, 60, 120, 150, 270 degrees!
Suppose that if
circle.Y>=this.Height-80
See this:
I really actually need to change the direction of rectangle movement using angles! so that at certain location reaches I can change the rectangle direction according to angle of my own choice!
such that:
if(circle.Y>=this.Height-80)
move in the direction of 90 degrees
if(circle.X>=this.Width-80)
move in the direction of 60 degree
as you can see in the screen shot!
What I have been trying is:
public partial class Form1 : Form
{
Rectangle circle;
double dx = 2;
double dy = 2;
public Form1()
{
InitializeComponent();
circle = new Rectangle(10, 10, 40, 40);
}
private void Form1_Load(object sender, EventArgs e)
{
this.Refresh();
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
Graphics g = e.Graphics;
g.SmoothingMode = SmoothingMode.AntiAlias;
g.FillEllipse(new SolidBrush(Color.Red), circle);
}
private void timer_Tick(object sender, EventArgs e)
{
circle.X += (int)dx;
circle.Y += (int)dy;
if (circle.Y>=this.Height-80)
{
dy = -Math.Acos(0) * dy/dy; //here i want to change the direction of circle at 90 degrees so that it should go up vertically straight with same speed
}
this.Refresh();
}
}
The Problem is that I have been trying changing my conditions to:
dy = -Math.Asin(1) * dy;
dx = Math.Acos(0) * dx ;
but in both cases nothing is happening and the direction remains same!
I just want to move the circle in inverted upward direction at 90 degrees when it reach at
circle.Y>=this.Height-80
You need to draw the rectangle again to some image for it to display. I created this code for moving and drawing rectangle on pictureBox1, using your already defined circle-rectangle:
Moving the rectangle:
public void MoveRectangle(ref Rectangle rectangle, double angle, double distance)
{
double angleRadians = (Math.PI * (angle) / 180.0);
rectangle.X = (int)((double)rectangle.X - (Math.Cos(angleRadians) * distance));
rectangle.Y = (int)((double)rectangle.Y - (Math.Sin(angleRadians) * distance));
}
Drawing the rectangle and displaying it in the PictureBox:
public void DrawRectangle(Rectangle rectangle)
{
Bitmap bmp = new Bitmap(pictureBox1.Width, pictureBox1.Height);
using (Graphics g = Graphics.FromImage(bmp))
{
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
g.FillEllipse(new SolidBrush(Color.Red), rectangle);
}
pictureBox1.Image = bmp;
}
Demo it with a button click:
private void Button1_Click(object sender, EventArgs e)
{
MoveRectangle(ref circle, 90, 5);
DrawRectangle(circle);
}
Math.Asin(1) * dy is a constant value. Thus, you should use, for example, an instance variable that increments in each Tick of your timer.
...And *dy/dy is irrelevant.
public partial class Form1 : Form
{
Rectangle circle;
double dx = 2;
double dy = 2;
acum=0; //the new variable
...
private void timer_Tick(object sender, EventArgs e)
{
circle.X += (int)dx;
circle.Y += (int)dy;
if (circle.Y>=this.Height-300)
{
dy = -Math.Acos(acum);
acum+=1; //your accumulator
}
this.Refresh();
}
acos and asin are the inverse of sin and cos so the output of those two functions is an angle (usually in radians). This makes the code incorrect.
I strongly suggest that you read up on vector and matrix maths as using Euler angles can get quite messy.
So, you will have a position vector P and a movement vector M and the current position is:
P' = P + M.t
where t is time, P is the original position and P' is the current position.
Then, when you want to change direction, you create a rotation matrix and multiply the movement vector M by this rotation matrix.
The advantage here is that you can step from a 2D system to a 3D system by adding a Z component to your vectors and increasing the size of your matrices.
i have PictureBox, how can I draw a shape/line that fires on MouseEnter event and change color or do more.
private void ImgViewer_Paint(object sender, PaintEventArgs e)
{
var graph = e.Graphics;
using (var pen = new Pen(Color.FromArgb(0, 255, 0)))
graph.DrawLine(pen, x1, y1, x2, y2);
}
this code is not enough, i guess
If you know the equation of the shape you could calculate whether the mouse is within or outside the shape area. Note that this is easy if the shape is consisted of the straight lines or circles (ellipses) for which the geometrical equations are relatively simple. For instance if your shape is a triangle with x and y coordinates (10,10), (50,10) and (30,50) than you should derive the equations of the lines using the equation of the line in two points:
y-y1 = ((y2-y1)/(x2-x1))*(x-x1)
the equations of the lines of our triangle would be:
y=1
y=2*x-10
y=-2*x+110
We should draw that triangle on some canvas, let's say on the PictureBox with FixedSingle border. Add the Paint event handler
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
Point[] p = new Point[3];
p[0] = new Point(10,10);
p[1] = new Point(50,10);
p[2] = new Point(30,50);
e.Graphics.DrawLines(Pens.Black, p);
e.Graphics.FillPolygon(Brushes.Red, p);
}
We should add the MouseMove event handler for the PictureBox
bool inside = false;
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (e.Y > 10 && e.Y < 2 * e.X - 10 && e.Y < -2 * e.X + 110)
{
if (!inside)
{
inside = true;
HandleMouseEnter();
}
}
else
inside = false;
}
void HandleMouseEnter()
{
MessageBox.Show("Mouse inside");
}
In if statement whether the mouse cursor is within the triangle (note that the coordinate origin in C# is on the top-left corner but it is similar to the real geometry). The HandleMouseEnter is the method that handles the mouse enter.
You could use similar approach for an arbitrary shape but you should have geometry equations that describe it.
I have a program in C# (Windows Forms) which has a rectangle on a Picture Box. They can be drawn at an angle too (rotated). I want to rotate that rectangle using my mouse movements.
I have the code for moving that rectangle
Rectangle areaRect = new Rectangle(100,100, 300, 300);
Bool dragging = false;
Point ptOld = new Point(0, 0);
protected override void OnPaint(PaintEventArgs e)
{
Graphics dcPaint = e.Graphics;
dcPaint.DrawRectangle(rectPen, areaRect);
}
protected override void OnMouseDown(MouseEventArgs e)
{
ptOld = new Point(e.X, e.Y);
dragging = true;
}
protected override void OnMouseMove(MouseEventArgs e)
{
if(dragging = true)
{
Point ptNew = new Point(e.X, e.Y);
int dx = ptNew.X - ptOld.X;
int dy = ptNew.Y - ptOld.Y;
areaRect.Offset(dx, dy); // This one moves the rectangle
ptOld = ptNew;
this.Invalidate();
}
}
protected override void OnMouseUp(MouseEventArgs e)
{
dragging = false;
}
Now My requirement is to rotate this rectangle, Any idea, how that can be achieved.
I think you want to calculate angle between two points on X-axis. If so, try the following code:
const double Rad2Deg = 180.0 / Math.PI;
return Math.Atan2(ptOld.Y - e.Y, e.X - ptOld.X) * Rad2Deg;
Also check out this article on calculating angle between two points
When rotating rectangle with mouse, you define the center of rotation (centerXY), in you case it will be the center of the rectangle maybe.
On mouse down record mouse coordinates, mouse_downXY. These two points define a base line. When moving mouse you'll define another line, formed by current mouse coordinates and the rectangle center.
So you'll need to compute the angle between line (centerXY, mouse_downXY) and (centerXY, current_mouseXY). Computing angle between 2 lines with knowing 3 points coordinates is simple trigonometry, so I won't write code for you :) However this post has the answer.
You can calculate the angle using the difference between the old and the new x mouse coordinate (dx in your example). You can use the RotateTransform method of the Graphics object to rotate the rectangle.
I modified your code to do the rotation in addition to the translation. You can move the rectangle with the left mouse button and you can rotate it using the right mouse button.
Rectangle areaRect = new Rectangle(100, 100, 300, 300);
bool dragging = false;
bool rotating = false;
Point ptOld = new Point(0, 0);
float angle = 0;
protected override void OnPaint(PaintEventArgs e)
{
Graphics dcPaint = e.Graphics;
dcPaint.RotateTransform(angle);
dcPaint.DrawRectangle(Pens.Black, areaRect);
dcPaint.RotateTransform(-angle);
}
protected override void OnMouseDown(MouseEventArgs e)
{
ptOld = new Point(e.X, e.Y);
if (e.Button == MouseButtons.Left)
{
dragging = true;
}
if (e.Button == MouseButtons.Right)
{
rotating = true;
}
}
protected override void OnMouseMove(MouseEventArgs e)
{
if (dragging == true)
{
Point ptNew = new Point(e.X, e.Y);
int dx = ptNew.X - ptOld.X;
int dy = ptNew.Y - ptOld.Y;
areaRect.Offset(dx, dy); // This one moves the rectangle
ptOld = ptNew;
this.Invalidate();
}
if (rotating == true)
{
Point ptNew = new Point(e.X, e.Y);
int dx = ptNew.X - ptOld.X;
angle = angle + dx / 10f;
ptOld = ptNew;
this.Invalidate();
}
}
protected override void OnMouseUp(MouseEventArgs e)
{
dragging = false;
rotating = false;
}
Right now, the rectangle is rotated around its top left corner. If you apply a translation before the rotation, you can get it to rotate around its middle.