System.Drawing is only for GDI+ WinForms drawing, you can’t use it with MonoGame. I worked on a primitive drawing library a while back and it’s been imported into MonoGame.Extended. You can get it from there 
For PointF you just use Vector2, and for RectangleF I have a class I wrote a while ago that you can just use. I’ll post it here.
You’ll need both of these, SizeF and RectangleF. Just put them in their own files.
using Microsoft.Xna.Framework;
namespace ArbitraryPixel.Common.Drawing
{
/// <summary>
/// Represents a size structure, containing width and height.
///
/// This object is intended to reproduce the behaviour of System.Drawing.Size and
/// Sytem.Drawing.SizeF, except use doubles for its internal storage.
/// </summary>
public struct SizeF
{
#region Private Members
private float _width;
private float _height;
#endregion
#region Static Members
/// <summary>
/// Represents an empty MTPSize object, where the width and height are zero.
/// </summary>
public static readonly SizeF Empty;
#endregion
#region Constructor(s)
/// <summary>
/// Constructs a new object.
/// </summary>
/// <param name="width">The desired width.</param>
/// <param name="height">The desired height.</param>
public SizeF(float width, float height)
{
_width = width;
_height = height;
}
/// <summary>
/// Constructs a new object.
/// </summary>
/// <param name="value">The value that both width and height will be set to.</param>
public SizeF(float value)
{
_width = value;
_height = value;
}
#endregion
#region Public Properties
/// <summary>
/// The width for this size object.
/// </summary>
public float Width
{
get { return _width; }
set { _width = value; }
}
/// <summary>
/// The height for this object.
/// </summary>
public float Height
{
get { return _height; }
set { _height = value; }
}
/// <summary>
/// Get a point representing the centre point of this SizeF object.
/// </summary>
public Vector2 Centre
{
get { return new Vector2(_width / 2f, _height / 2f); }
}
#endregion
#region Operators and Overrides
/// <summary>
/// Compare two MTPSize objects for equality.
/// </summary>
/// <param name="left">The left hand side of the comparison.</param>
/// <param name="right">The right hand side of the comparison.</param>
/// <returns>True if the left and right are equivalent; that is, they have equal values. False otherwise.</returns>
public static bool operator ==(SizeF left, SizeF right)
{
return (left.Width == right.Width && left.Height == right.Height);
}
/// <summary>
/// Compare two MTPSize objects for inequality.
/// </summary>
/// <param name="left">The left hand side of the comparison.</param>
/// <param name="right">The right hand side of the comparison.</param>
/// <returns>True if the left and right side are not equivalent; that is, they have different values. False otherwise.</returns>
public static bool operator !=(SizeF left, SizeF right)
{
return !(left == right);
}
/// <summary>
/// Creates a string representation of this object.
/// </summary>
/// <returns>The string representation of this object.</returns>
public override string ToString()
{
// This is based on the string format of System.Drawing.Size and System.Drawing.SizeF.
return string.Format("{{Width={0}, Height={1}}}", _width, _height);
}
/// <summary>
/// Checks to see if an object is equal to this object.
/// </summary>
/// <param name="obj">The object to test.</param>
/// <returns>True if the supplied object is equal to this one, false otherwise.</returns>
public override bool Equals(object obj)
{
bool isEqual = false;
if (obj is SizeF)
{
isEqual = ((SizeF)obj) == this;
}
return isEqual;
}
/// <summary>
/// Get the hash code for this object.
/// </summary>
/// <returns>The hash code for this object.</returns>
public override int GetHashCode()
{
int hash = 17;
unchecked
{
hash = hash * 29 + _width.GetHashCode();
hash = hash * 29 + _height.GetHashCode();
}
return hash;
}
/// <summary>
/// Cast a SizeF object to a Vector2 object.
/// </summary>
/// <param name="size">The SizeF object to cast.</param>
/// <returns>The SizeF object as an equivalent Vector2 object.</returns>
public static implicit operator Vector2(SizeF size)
{
return new Vector2(size.Width, size.Height);
}
/// <summary>
/// Cast a Vector2 object to a SizeF object.
/// </summary>
/// <param name="vector">The Vector2 object to cast.</param>
/// <returns>The Vector2 object as an equivalent SizeF object.</returns>
public static explicit operator SizeF(Vector2 vector)
{
return new SizeF(vector.X, vector.Y);
}
/// <summary>
/// Cast a SizeF object to a Point object.
/// </summary>
/// <param name="size">The SizeF object to cast.</param>
/// <returns>The SizeF object as an equivalent Point object.</returns>
public static explicit operator Point(SizeF size)
{
return new Point((int)size.Width, (int)size.Height);
}
/// <summary>
/// Cast a Point object to a SizeF object.
/// </summary>
/// <param name="p">The Point object to cast.</param>
/// <returns>The Point object as an equivalent SizeF object.</returns>
public static explicit operator SizeF(Point p)
{
return new SizeF(p.X, p.Y);
}
/// <summary>
/// Multiply a SizeF object by a float.
/// </summary>
/// <param name="lhs">The SizeF object.</param>
/// <param name="rhs">The float.</param>
/// <returns>A SizeF object that is the result of the multiplication of the float by both the Width and Height. Effectively a scale operation.</returns>
public static SizeF operator *(SizeF lhs, float rhs)
{
return new SizeF(lhs.Width * rhs, lhs.Height * rhs);
}
/// <summary>
/// Multiply a SizeF object by another SizeF object.
/// </summary>
/// <param name="lhs">The first SizeF object.</param>
/// <param name="rhs">The second SizeF object.</param>
/// <returns>A new SizeF object where the Width and Height are equal to the product of the supplied objects' Width and Height respectively.</returns>
public static SizeF operator *(SizeF lhs, SizeF rhs)
{
return new SizeF(lhs.Width * rhs.Width, lhs.Height * rhs.Height);
}
/// <summary>
/// Divide a SizeF object by a float.
/// </summary>
/// <param name="lhs">The SizeF object.</param>
/// <param name="rhs">The float.</param>
/// <returns>A new SizeF object that is the result of the division by the float of the Width and the Height of the SizeF object.</returns>
public static SizeF operator /(SizeF lhs, float rhs)
{
return new SizeF(lhs.Width / rhs, lhs.Height / rhs);
}
/// <summary>
/// Divide a SizeF object by another SizeF object.
/// </summary>
/// <param name="lhs">The first SizeF object.</param>
/// <param name="rhs">The second SizeF object.</param>
/// <returns>A new SizeF object where the Width and Height are equal to the quotient of the supplied object's Width and Height respectively.</returns>
public static SizeF operator /(SizeF lhs, SizeF rhs)
{
return new SizeF(lhs.Width / rhs.Width, lhs.Height / rhs.Height);
}
/// <summary>
/// Add a SizeF object with another SizeF object.
/// </summary>
/// <param name="lhs">The first SizeF object.</param>
/// <param name="rhs">The second SizeF object.</param>
/// <returns>A new SizeF object where the Width and Height are equal to the sum of the supplied objects' Width and Height respectively.</returns>
public static SizeF operator +(SizeF lhs, SizeF rhs)
{
return new SizeF(lhs.Width + rhs.Width, lhs.Height + rhs.Height);
}
/// <summary>
/// Subtract a SizeF object from another SizeF object.
/// </summary>
/// <param name="lhs">The first SizeF object.</param>
/// <param name="rhs">The second SizeF object.</param>
/// <returns>A new SizeF object where the Width and Height are equal to the difference of the supplied objects' Width and Height respectively.</returns>
public static SizeF operator -(SizeF lhs, SizeF rhs)
{
return new SizeF(lhs.Width - rhs.Width, lhs.Height - rhs.Height);
}
/// <summary>
/// Multiplies both the width and height by -1.
/// </summary>
/// <param name="value">The SizeF object to operate on.</param>
/// <returns>The SizeF object where the Width and Height have been multiplied by -1.</returns>
public static SizeF operator -(SizeF value)
{
return new SizeF(-value.Width, -value.Height);
}
#endregion
}
}
using Microsoft.Xna.Framework;
using System;
namespace ArbitraryPixel.Common.Drawing
{
/// <summary>
/// Represents a rectangle structure, having both a location, as well a width and height.
/// The width and height of a rectangle are relative to the location; therefore, they can
/// be negative.
///
/// This object is intended to reproduce the behaviour of System.Drawing.Rectangle and
/// Sytem.Drawing.RectangleF, except use doubles for its internal storage.
/// </summary>
public struct RectangleF
{
#region Private Members
private Vector2 _location;
private SizeF _size;
#endregion
#region Constructor(s)
/// <summary>
/// Create a new rectangle object.
/// </summary>
/// <param name="location">The location of this rectangle.</param>
/// <param name="size">The size of this rectangle.</param>
public RectangleF(Vector2 location, SizeF size)
{
_location = location;
_size = size;
}
/// <summary>
/// Create a new rectangle object.
/// </summary>
/// <param name="p1">The first corner of this rectangle.</param>
/// <param name="p2">The second corner of this rectangle.</param>
public RectangleF(Vector2 p1, Vector2 p2)
: this(p1, new SizeF(p2.X - p1.X, p2.Y - p1.Y))
{
}
/// <summary>
/// Create a new rectangle object.
/// </summary>
/// <param name="x">The X coordinate of the location.</param>
/// <param name="y">The Y coordinate of the location.</param>
/// <param name="width">The width of this rectangle.</param>
/// <param name="height">The height of this rectangle.</param>
public RectangleF(float x, float y, float width, float height)
: this(new Vector2(x, y), new SizeF(width, height))
{
}
#endregion
#region Static Members
/// <summary>
/// Represents an empty rectangle, where the location and size are initialized to zero.
/// </summary>
public static readonly RectangleF Empty;
#endregion
#region Public Properties
/// <summary>
/// The location of this rectangle.
/// </summary>
public Vector2 Location
{
get { return _location; }
set { _location = value; }
}
/// <summary>
/// The size of this rectangle.
/// </summary>
public SizeF Size
{
get { return _size; }
set { _size = value; }
}
/// <summary>
/// The X coordinate of this rectangle's location.
/// </summary>
public float X
{
get { return _location.X; }
set { _location.X = value; }
}
/// <summary>
/// The Y coordinate of this rectangle's location.
/// </summary>
public float Y
{
get { return _location.Y; }
set { _location.Y = value; }
}
/// <summary>
/// The width of this rectangle.
/// </summary>
public float Width
{
get { return _size.Width; }
set { _size.Width = value; }
}
/// <summary>
/// The height of this rectangle.
/// </summary>
public float Height
{
get { return _size.Height; }
set { _size.Height = value; }
}
/// <summary>
/// The location of this rectangle's opposite corner (relative to its location).
/// </summary>
public Vector2 OppositeCorner
{
get { return new Vector2(_location.X + _size.Width, _location.Y + _size.Height); }
}
/// <summary>
/// The Y coordinate for this rectangle's top edge.
/// </summary>
public float Top { get { return this.Y; } }
/// <summary>
/// The X coordinate for this rectangle's left edge.
/// </summary>
public float Left { get { return this.X; } }
/// <summary>
/// The X coordinate for this rectangle's right edge.
/// </summary>
public float Right { get { return this.X + this.Width; } }
/// <summary>
/// The Y coordinate for this rectangle's bottom edge.
/// </summary>
public float Bottom { get { return this.Y + this.Height; } }
/// <summary>
/// The centre point of this rectangle.
/// </summary>
public Vector2 Centre
{
get
{
return new Vector2(this.Left + this.Width / 2f, this.Top + this.Height / 2f);
}
}
#endregion
#region Operators and Overloads
/// <summary>
/// Compare two rectangles for equality.
/// </summary>
/// <param name="left">The left rectangle.</param>
/// <param name="right">The right rectangle.</param>
/// <returns>True if both rectangles have the same location and size, false otherwise.</returns>
public static bool operator ==(RectangleF left, RectangleF right)
{
Vector2 aMin = new Vector2(Math.Min(left.Left, left.Right), Math.Min(left.Top, left.Bottom));
Vector2 aMax = new Vector2(Math.Max(left.Left, left.Right), Math.Max(left.Top, left.Bottom));
Vector2 bMin = new Vector2(Math.Min(right.Left, right.Right), Math.Min(right.Top, right.Bottom));
Vector2 bMax = new Vector2(Math.Max(right.Left, right.Right), Math.Max(right.Top, right.Bottom));
return (aMin == bMin && aMax == bMax);
}
/// <summary>
/// Compare two rectangles for inequality.
/// </summary>
/// <param name="left">The left rectangle.</param>
/// <param name="right">The right rectangle.</param>
/// <returns>True if both rectangles have different locations or sizes, false otherwise.</returns>
public static bool operator !=(RectangleF left, RectangleF right)
{
return !(left == right);
}
/// <summary>
/// Creates a string representation of this object.
/// </summary>
/// <returns>The string representation of this object.</returns>
public override string ToString()
{
// This is based on the string format of System.Drawing.Rectangle and System.Drawing.RectangleF.
return string.Format("{{X={0}, Y={1}, Width={2}, Height={3}}}", this.X, this.Y, this.Width, this.Height);
}
/// <summary>
/// Checks to see if an object is equal to this object.
/// </summary>
/// <param name="obj">The object to test.</param>
/// <returns>True if the supplied object is equal to this one, false otherwise.</returns>
public override bool Equals(object obj)
{
bool isEqual = false;
if (obj is RectangleF)
{
isEqual = ((RectangleF)obj) == this;
}
return isEqual;
}
/// <summary>
/// Get the hash code for this object.
/// </summary>
/// <returns>The hash code for this object.</returns>
public override int GetHashCode()
{
int hash = 17;
unchecked
{
hash = hash * 29 + _location.GetHashCode();
hash = hash * 29 + _size.GetHashCode();
}
return hash;
}
#endregion
#region Public Methods
/// <summary>
/// Adjust the edges of this rectangle by the specified amounts.
/// </summary>
/// <param name="horizontalAmount">The amount to adjust the left and right edges.</param>
/// <param name="verticalAmount">The amount to adjust the top and buttom edges.</param>
public void Inflate(float horizontalAmount, float verticalAmount)
{
this.X -= horizontalAmount;
this.Width += horizontalAmount * 2; ;
this.Y -= verticalAmount;
this.Height += verticalAmount * 2;
}
/// <summary>
/// Adjust the edges of this rectangle by the specified size.
/// </summary>
/// <param name="amount">A SizeF value to adjust by, using Width as the horizontal amount and Height as the vertical amount.</param>
public void Inflate(SizeF amount)
{
this.Inflate(amount.Width, amount.Height);
}
/// <summary>
/// Tests to see if a point is contained within this rectangle.
///
/// NOTE: This method deviates from the System.Drawing equivalents. This method will work
/// with return the correct result when width and height are negative.
/// </summary>
/// <param name="point">The point to test.</param>
/// <returns>True if the point is inside the rectangle, false otherwise.</returns>
public bool Contains(Vector2 point)
{
Vector2 min = new Vector2(Math.Min(this.Left, this.Right), Math.Min(this.Top, this.Bottom));
Vector2 max = new Vector2(Math.Max(this.Left, this.Right), Math.Max(this.Top, this.Bottom));
return (point.X >= min.X && point.X < max.X && point.Y >= min.Y && point.Y < max.Y);
}
/// <summary>
/// Tests to see if a point is contained within this rectangle.
/// </summary>
/// <param name="x">The X coordinate of the point.</param>
/// <param name="y">The Y coordinate of the point.</param>
/// <returns>True if the point is inside the rectangle, false otherwise.</returns>
public bool Contains(float x, float y)
{
return this.Contains(new Vector2(x, y));
}
/// <summary>
/// Tests to see if a rectangle is contained within this rectangle.
///
/// NOTE: This method deviates from the System.Drawing equivalents. This method will work
/// with return the correct result when width and height are negative.
/// </summary>
/// <param name="rect">The rectangle to test.</param>
/// <returns>True if the supplied rectangle is contained by this object, false otherwise.</returns>
public bool Contains(RectangleF rect)
{
Vector2 thisMin = new Vector2(Math.Min(this.Left, this.Right), Math.Min(this.Top, this.Bottom));
Vector2 thisMax = new Vector2(Math.Max(this.Left, this.Right), Math.Max(this.Top, this.Bottom));
Vector2 rectMin = new Vector2(Math.Min(rect.Left, rect.Right), Math.Min(rect.Top, rect.Bottom));
Vector2 rectMax = new Vector2(Math.Max(rect.Left, rect.Right), Math.Max(rect.Top, rect.Bottom));
return (rectMin.X >= thisMin.X && rectMax.X <= thisMax.X && rectMin.Y >= thisMin.Y && rectMax.Y <= thisMax.Y);
}
/// <summary>
/// Tests to see if a rectangle intersects with this rectangle.
///
/// NOTE: This method deviates from the System.Drawing equivalents. This method will work
/// with return the correct result when width and height are negative.
/// </summary>
/// <param name="rect">The rectangle to test.</param>
/// <returns>True if this object and the supplied rectangle intersect, false otherwise.</returns>
public bool IntersectsWith(RectangleF rect)
{
Vector2 thisMin = new Vector2(Math.Min(this.Left, this.Right), Math.Min(this.Top, this.Bottom));
Vector2 thisMax = new Vector2(Math.Max(this.Left, this.Right), Math.Max(this.Top, this.Bottom));
Vector2 rectMin = new Vector2(Math.Min(rect.Left, rect.Right), Math.Min(rect.Top, rect.Bottom));
Vector2 rectMax = new Vector2(Math.Max(rect.Left, rect.Right), Math.Max(rect.Top, rect.Bottom));
return !((rectMax.X <= thisMin.X || rectMin.X >= thisMax.X) || (rectMin.Y >= thisMax.Y || rectMax.Y <= thisMin.Y));
}
/// <summary>
/// Generate a new rectangle that is the intersection of two rectangles; that is, the portion
/// common to both rectangles (overlap).
///
/// NOTE: This method deviates from the System.Drawing equivalents. This method will work
/// with return the correct result when width and height values are negative.
/// </summary>
/// <param name="a">The first rectangle.</param>
/// <param name="b">The second rectangle.</param>
/// <returns>A rectangle representing the common area of the two rectangles.</returns>
public static RectangleF Intersect(RectangleF a, RectangleF b)
{
RectangleF result = RectangleF.Empty;
if (a.IntersectsWith(b))
{
Vector2 aMin = new Vector2(Math.Min(a.Left, a.Right), Math.Min(a.Top, a.Bottom));
Vector2 aMax = new Vector2(Math.Max(a.Left, a.Right), Math.Max(a.Top, a.Bottom));
Vector2 bMin = new Vector2(Math.Min(b.Left, b.Right), Math.Min(b.Top, b.Bottom));
Vector2 bMax = new Vector2(Math.Max(b.Left, b.Right), Math.Max(b.Top, b.Bottom));
result.X = Math.Max(aMin.X, bMin.X);
result.Y = Math.Max(aMin.Y, bMin.Y);
result.Width = Math.Min(aMax.X, bMax.X) - result.X;
result.Height = Math.Min(aMax.Y, bMax.Y) - result.Y;
}
return result;
}
/// <summary>
/// Generate a new rectangle that is the union of two rectangles; that is, the
/// rectangle that would minimally contain both supplied rectangles.
///
/// NOTE: This method deviates from the System.Drawing equivalents. This method will work
/// with return the correct result when width and height values are negative.
/// </summary>
/// <param name="a">The first rectangle.</param>
/// <param name="b">The second rectangle.</param>
/// <returns>A rectangle representing the union of the two rectangles.</returns>
public static RectangleF Union(RectangleF a, RectangleF b)
{
RectangleF result = RectangleF.Empty;
Vector2 aMin = new Vector2(Math.Min(a.Left, a.Right), Math.Min(a.Top, a.Bottom));
Vector2 aMax = new Vector2(Math.Max(a.Left, a.Right), Math.Max(a.Top, a.Bottom));
Vector2 bMin = new Vector2(Math.Min(b.Left, b.Right), Math.Min(b.Top, b.Bottom));
Vector2 bMax = new Vector2(Math.Max(b.Left, b.Right), Math.Max(b.Top, b.Bottom));
result.X = Math.Min(aMin.X, bMin.X);
result.Y = Math.Min(aMin.Y, bMin.Y);
result.Width = Math.Max(aMax.X, bMax.X) - result.X;
result.Height = Math.Max(aMax.Y, bMax.Y) - result.Y;
return result;
}
#endregion
#region Casting
/// <summary>
/// Cast a RectangleF object to a Rectangle object.
/// </summary>
/// <param name="rect">The RectangleF object to cast.</param>
/// <returns>A Rectangle object which is equivalent to the supplied RectangleF object.</returns>
public static explicit operator Rectangle(RectangleF rect)
{
return new Rectangle((int)Math.Floor(rect.X), (int)Math.Floor(rect.Y), (int)Math.Floor(rect.Width), (int)Math.Floor(rect.Height));
}
/// <summary>
/// Cast a Rectangle object to a RectangleF object.
/// </summary>
/// <param name="rect">The Rectangle object to cast.</param>
/// <returns>A RectangleF object which is equivalent to the supplied Rectangle object.</returns>
public static explicit operator RectangleF(Rectangle rect)
{
return new RectangleF(rect.X, rect.Y, rect.Width, rect.Height);
}
#endregion
}
}
