C # Cutting Rectangle

Question

I have a code that generates rectangles with an arbitrary angle:

But I need to cut the child rectangle along the parent border, for example

My code: http://pastebin.com/b6ry8j68

Can someone help me with an algorithm?

Answer 1

This is pretty easy to do with the SetClip property .

basically you need to add this code:

if (!pre_defined) { g.SetClip(new Rectangle(x, y, 600, 300)); } 

right before the drawline commands. where x and y are the coordinates of your parent rectangle. which is easy to get from your function.

this is a complete function that works:

  public void drawRectangle(double Width, double Height, int A, bool pre_defined) { Graphics g = pictureBox1.CreateGraphics(); g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; System.Drawing.Brush brush = new System.Drawing.SolidBrush(Color.FromArgb(r.Next(0, 251), r.Next(0, 251), r.Next(0, 251))); Pen myPen = new Pen(brush, 2); myPen.Width = 2; int x = center.X; int y = center.Y; //top left P[0] = new PointF((float)Math.Round(x + (Width / 2) * Math.Cos(A) + (Height / 2) * Math.Sin(A)), (float)Math.Round(y - (Height / 2) * Math.Cos(A) + (Width / 2) * Math.Sin(A))); //top right P[1] = new PointF((float)Math.Round(x - (Width / 2) * Math.Cos(A) + (Height / 2) * Math.Sin(A)), (float)Math.Round(y - (Height / 2) * Math.Cos(A) - (Width / 2) * Math.Sin(A))); //bottom left P[2] = new PointF((float)Math.Round(x + (Width / 2) * Math.Cos(A) - (Height / 2) * Math.Sin(A)), (float)Math.Round(y + (Height / 2) * Math.Cos(A) + (Width / 2) * Math.Sin(A))); //bottom right P[3] = new PointF((float)Math.Round(x - (Width / 2) * Math.Cos(A) - (Height / 2) * Math.Sin(A)), (float)Math.Round(y + (Height / 2) * Math.Cos(A) - (Width / 2) * Math.Sin(A))); if (!pre_defined) { g.SetClip(new Rectangle(50, 50, 600, 300)); } g.DrawLine(myPen, P[0], P[1]); g.DrawLine(myPen, P[1], P[3]); g.DrawLine(myPen, P[3], P[2]); g.DrawLine(myPen, P[2], P[0]); } 

EDIT:
this is not a complete example, since it will only set Clip to the parent width and height. You need to change your function to ensure the width and height of each element. But now I look at the photo you provided, and it looks more complicated than I thought.
You will probably be able to save an array of all the random values ​​and arrange it by size, and then draw all the elements.

Answer 2

This is an old question, but someone may still need a simple workaround.

The simplest solution is to draw these rectangles on a graphic surface of a certain size so that any drawing paths that go beyond that size or border are automatically cropped. Creating a graphic object from a bitmap of a certain size compresses something to that size. After that, the bitmap can be drawn on the screen of a graphic object for drawing directly on the screen.

Note that this process is also used as a double buffering method, which helps to reduce the effects of flickering when drawing directly on the screen.

The following example shows how to set up a dimensional graphic object.

See: PaintEventArgs Override Information

  ///<summary> /// Most common method for painting to the screen. /// Available on all control class objects by overriding /// the OnPaint method of the base class. ///</summary> protected virtual new void OnPaint(PaintEventArgs e) { // We assume here that your control screen graphics // area is at least 500x400 to see the full results // otherwise please resize your form or control to accommodate // Define your parent border size Size ParentBorder = new Size(400, 300); // Initialize a new bitmap having a size of ParentBorder and set // it to the screen pixel format. Setting the bitmap to the // screens pixel format can save many milliseconds in processing // due to pixel size conversions otherwise required Bitmap Bmp = new Bitmap(ParentBorder.Width, ParentBorder.Height, Graphics.FromHwnd(IntPtr.Zero)); // Next we create a graphics object tied to our bitmap for // drawing our rectangles within a defined border Graphics BmpGfx = Graphics.FromImage(Bmp); // // Draw your rectangles here! A sample is below includes painting // to the screen to illustrate this process // // // Rotate first rectangle 20 or transform as needed :) BmpGfx.RotateTransform(20); // // Sample 1: This one just shows a red rectangle near the center // of the ParentBorder graphics object BmpGfx.DrawRectangle(new Pen(Color.Red), new Rectangle(new Point(100, -20), new Size(200, 200))); // // Reset back to normal transform BmpGfx.ResetTransform(); // // Rotate second rectangle 60 BmpGfx.RotateTransform(60); // // Sample 2: This one just shows a cropped blue rectangle at // the borders BmpGfx.DrawRectangle(new Pen(Color.Blue), new Rectangle(new Point(145, -200), new Size(300, 300))); // // Reset back to normal transform for drawing a nice ParentBorder BmpGfx.ResetTransform(); // // Border: This one just draws an Orange border around the ParaentBorder // of the Bmp graphics object BmpGfx.DrawRectangle(new Pen(Color.Orange), new Rectangle(Point.Empty, new Size(Bmp.Width - 1, Bmp.Height - 1))); // Finally put your drawing to the screen. 50 points left and top so // you can see the border and that nothing exceeds that ParaentBorder e.Graphics.DrawImage(Bmp, new Point(50,50)); // Save your BMP to a file if you prefer or to "preserve the graphics" // place the bmp in global scope (a global variable just don't forget // to dispose when no longer needed) // Please dispose of your goods as variable objects not inline like // done above to keep the GC happy of course. The below method ensures // resources are fully released for immediate cleanup by the GC. Bmp.Dispose(); Bmp = null; BmpGfx.Dispose(); BmpGfx = null; }