How can I fill a rotated rectangle over an image?

Question

How can i fill a rotated rectangle? I can only fill a rectangle that is not rotated and it works fine. But i recently need to fill a rotated rectangle on any degree.

This is my code

using (ImageMagick.MagickImage img = new ImageMagick.MagickImage())
{

 img.Read(image.FullPath);
 foreach (var item in ListofCoordinates)
{

ImageMagick.DrawableFillColor fillColor = new ImageMagick.DrawableFillColor(System.Drawing.Color.LightGray);

var d = int.Parse(Math.Round(((item.Rotation * img.Density.X) / 96)).ToString());
var x = int.Parse(Math.Round(((item.X * img.Density.X) / 96)).ToString());
var y = int.Parse(Math.Round(((item.Y * img.Density.X) / 96)).ToString());
var w = int.Parse(Math.Round(((item.Width * img.Density.X) / 96)).ToString());
var h = int.Parse(Math.Round(((item.Height * img.Density.X) / 96)).ToString());
var r = new System.Drawing.Rectangle(x, y, w, h);

ImageMagick.DrawableRectangle rect = new ImageMagick.DrawableRectangle(r);
img.Draw(fillColor, rect);

}

img.Write(System.IO.Path.Combine(OutputPath, image.FileName));
}

This is a sample of what i should achieve

This is the sample image this is the First picture

This is the output This is the second picture which is the output

Answer 1

Well, while you could use ImageMagic, the .Net libraries are sufficient.

There are few ways to draw shape like rotated rectangle.

1) Draw 4 points (you could draw any shape this way, not only rectangle), rotate it

C#

    Dim Img As Image = New Bitmap(Me.Picturebox1.Width, Me.Picturebox1.Height)
    Dim g As Graphics = Graphics.FromImage(Img)
    Dim bgBrush As SolidBrush = New SolidBrush(Color.LightSlateGray)
    Dim shPen As Pen = New Pen(Color.Black)

    Dim pts() As Point
    pts = {New Point(150, 100),         ' 1
           New Point(200, 100),         ' 2
           New Point(150, 200),         ' 3
           New Point(200, 200)}         ' 4

    Dim pth As New GraphicsPath
    pth = ShapeData(0)
    g.FillPath(bgBrush, pth)            ' fill
    g.DrawPath(shPen, pth)              ' border

    Dim Angle As Int16 = 30
    Dim RotMatrix As New Matrix                       ' rotate matrix to put the shape back to initial coordinates (with bottom left point as reference)
    RotMatrix.Rotate(Angle, MatrixOrder.Append)       ' Rotate the pattern to the desired angle
    RotMatrix.TransformPoints(pts)                    ' carry out matrix transformation over the shape points

VB.NET

Image Img = new Bitmap(this.Picturebox1.Width, this.Picturebox1.Height);
Graphics g = Graphics.FromImage(Img);
SolidBrush bgBrush = new SolidBrush(Color.LightSlateGray);
Pen shPen = new Pen(Color.Black);

Point[] pts;
pts = new[] { new Point(150, 100), new Point(200, 100), new Point(150, 200), new Point(200, 200) };         // 4

GraphicsPath pth = new GraphicsPath();
pth = ShapeData(0);
g.FillPath(bgBrush, pth);            // fill
g.DrawPath(shPen, pth);              // border

Int16 Angle = 30;
Matrix RotMatrix = new Matrix();                    // rotate matrix to put the shape back to initial coordinates (with bottom left point as reference)
RotMatrix.Rotate(Angle, MatrixOrder.Append);        // Rotate the pattern to the desired angle
RotMatrix.TransformPoints(pts);                     // carry out matrix transformation over the shape points

2) Draw 4 points already rotated

C#

    Dim Img As Image = New Bitmap(Me.Picturebox1.Width, Me.Picturebox1.Height)
    Dim g As Graphics = Graphics.FromImage(Img)
    Dim bgBrush As SolidBrush = New SolidBrush(Color.LightSlateGray)
    Dim shPen As Pen = New Pen(Color.Black)

    Dim pts() As Point
    pts = {New Point(150, 100),         ' 1 - rotated coordinates
           New Point(210, 110),         ' 2 - rotated coordinates
           New Point(140, 200),         ' 3 - rotated coordinates
           New Point(200, 210)}         ' 4 - rotated coordinates

    Dim pth As New GraphicsPath
    pth = ShapeData(0)
    g.FillPath(bgBrush, pth)            ' fill
    g.DrawPath(shPen, pth)              ' border

VB.NET

Image Img = new Bitmap(this.Picturebox1.Width, this.Picturebox1.Height);
Graphics g = Graphics.FromImage(Img);
SolidBrush bgBrush = new SolidBrush(Color.LightSlateGray);
Pen shPen = new Pen(Color.Black);

Point[] pts;
pts = new[] { new Point(150, 100), new Point(210, 110), new Point(140, 200), new Point(200, 210) };         // 4

GraphicsPath pth = new GraphicsPath();
pth = ShapeData(0);
g.FillPath(bgBrush, pth);            // fill
g.DrawPath(shPen, pth);              // border

3) Draw rectangle and rotate graphics. This might be little bit tricky.

C#

Image Img = new Bitmap(this.Picturebox1.Width, this.Picturebox1.Height);
Graphics g = Graphics.FromImage(Img);
SolidBrush bgBrush = new SolidBrush(Color.LightSlateGray);
Pen shPen = new Pen(Color.Black);

Int16 dDimX = 75;
Int16 dDimY = 150;
Int16 dLocX = 200;
Int16 dLocY = 100;
Rectangle rect = new Rectangle(dLocX, dLocY, dDimX, dDimY);

g.RotateTransform(30);

VB.NET

    Dim Img As Image = New Bitmap(Me.Picturebox1.Width, Me.Picturebox1.Height)
    Dim g As Graphics = Graphics.FromImage(Img)
    Dim bgBrush As SolidBrush = New SolidBrush(Color.LightSlateGray)
    Dim shPen As Pen = New Pen(Color.Black)

    Dim dDimX As Int16 = 75
    Dim dDimY As Int16 = 150
    Dim dLocX As Int16 = 200
    Dim dLocY As Int16 = 100
    Dim rect As Rectangle = New Rectangle(dLocX, dLocY, dDimX, dDimY)

    g.RotateTransform(30)