Racunarska grafika

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Racunarska grafika

• GDI
• (Graphics Device Interface Plus)

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Introduction

• Windows GDI is the portion of the Windows XP
  operating system or Windows Server 2003 operating
  system that provides two-dimensional vector
  graphics, imaging, and typography. GDI improves
  on Windows Graphics Device Interface (GDI) (the
  graphics device interface included with earlier
  versions of Windows) by adding new features and
  by optimizing existing features.

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The namespaces in GDI

• System.Drawing
• This is the core GDI namespace. It defines
  objects for basic rendering (fonts, pens, basic
  brushes, etc.) and the most important object
  Graphics.
• System.Drawing.Drawing2D
• This gives you objects for more advanced
  two-dimensional vector graphics. Some of them are
  gradient brushes, pen caps, and geometric
  transforms.

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The namespaces in GDI

• System.Drawing.Imaging
• If you want to change graphical images - that is,
  change the palette, extract image metadata,
  manipulate metafiles, and so forth - this is the
  one you need.
• System.Drawing.Printing
• To render images to the printed page, interact
  with the printer itself, and format the overall
  appearance of a print job, use the objects here.

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The namespaces in GDI

• System.Drawing.Text
• You can use collections of fonts with this
  namespace.

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Graphics object

• The place to start with GDI is
  the Graphics object. Although the things you draw
  show up on your monitor or a printer, the
  Graphics object is the "canvas" that you draw on.
• Graphics object is always associated with a
  particular device context.

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How do I get a Graphics object?

• You can get Graphics object from other objects.
  (e.g. event e parameter that is passed to
  the OnPaint event)
• You can use the CreateGraphicsmethod for a device
  context to create a Graphics object.

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Example

• private void Form1_Paint(object sender,
  PaintEventArgs e)
• Graphics g e.Graphics
• g.DrawLine(new Pen(Color.Red), 0, 0, 250, 250)
• -or-
• protected override void OnPaint(PaintEventArgs e)
• base.OnPaint(e)
• Graphics g e.Graphics
• g.DrawLine(new Pen(Color.Red), 0, 0, 250, 250)
• -or-
• private void button1_Click(object sender,
  EventArgs e)
• Graphics g this.CreateGraphics()
• g.DrawLine(new Pen(Color.Red), 0, 0, 250, 250)

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Vector Graphics versus Bitmaps

• "vector" is another word for a line, this way of
  using GDI is often called vector graphics.
• The other major type of graphics is create
  graphics using individual points of color like
  your TV or computer monitor does it. This is
  called bitmap graphics and will be covered in a
  later segment.

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Coordinate spaces

• There are three distinct coordinate spaces in
  GDI. These are
• World coordinate space. This is where you put the
  coordinates that define lines, shapes and points
  in the 2 dimensional space of the graphics
  system. World coordinates are abstract values
  expressed as floating point numbers. Essentially,
  whenever you draw something it goes into this
  coordinate space.
• Page Coordinate Space. The Page space is where
  the world coordinates are transformed into some
  real-world value. You can make the Page Space
  represent pixels, inches millimeters and so-on.
  This is what makes GDI a resolution independent
  system. You control how the page space interprets
  the world space by telling the Graphics object
  what PageUnit is being used and adjusting
  the PageScale.
• Device Coordinate Space. This space is controlled
  by the system and enables the real-world values
  in the Page Space to be translated to your screen
  or printer. Device space ensures that a 1 inch
  long line looks an inch long on the screen and on
  the printer even though the two devices may have
  very different pixel resolutions. You have no
  direct control over this space.

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Defining coordinate begining orentations

• Graphics g e.Graphics
• GraphicsState StanjePre g.Save()
• g.PageUnit GraphicsUnit.Pixel
• Matrix matricaTransformacija new Matrix(1, 0,
  0, -1, 0, 0)
• matricaTransformacija.Translate(this.ClientRectang
  le.Width / 2, -this.ClientRectangle.Height / 2)
• g.Transform matricaTransformacija
• g.DrawLine(new Pen(Color.FromArgb(255, 0, 0), 3),
  0, 0, 100, 100)
• g.Restore(StanjePre)
• g.DrawLine(new Pen(Color.FromArgb(0, 255, 0), 3),
  0, 0, 100, 100)

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Color

• Color.FromArgb(255, 0, 0)
• Color.FromArgb(128, 255, 0, 0)
• Color.FromName("red")
• Color.FromKnownColor(KnownColor.Red)
• Color.Red

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Pen
Name Description
Pen(Brush) Initializes a new instance of the Pen class with the specified Brush.
Pen(Color) Initializes a new instance of thePen class with the specified color.
Pen(Brush, Single) Initializes a new instance of the Pen class with the specified Brush and Width.
Pen(Color, Single) Initializes a new instance of the Pen class with the specified Color and Width properties.
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Pen

• // Create a new pen.
• Pen skyBluePen new
• Pen(Brushes.DeepSkyBlue)
• // Set the pen's width.
• skyBluePen.Width 8.0F
• // Set the LineJoin property.
• skyBluePen.LineJoin LineJoin.Bevel
• // Draw a rectangle.
• e.Graphics.DrawRectangle(skyBluePen, new
• Rectangle(40, 40, 150, 200))
• //Dispose of the pen.
• skyBluePen.Dispose()

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LineCap Start End 
Member Description
Flat Specifies a flat line cap.
Square Specifies a square line cap.
Round Specifies a round line cap.
Triangle Specifies a triangular line cap.
NoAnchor Specifies no anchor.
SquareAnchor Specifies a square anchor line cap.
RoundAnchor Specifies a round anchor cap.
DiamondAnchor Specifies a diamond anchor cap.
ArrowAnchor Specifies an arrow-shaped anchor cap.
Custom Specifies a custom line cap.
AnchorMask Specifies a mask used to check whether a line cap is an anchor cap.
Olovka.StartCap LineCap.DiamondAnchor Olovka.En
dCap LineCap.Triangle g.DrawLine(Olovka, 50,
500, 500, 500)
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LineJoin 
Member Description
Miter Specifies a mitered join. This produces a sharp corner or a clipped corner, depending on whether the length of the miter exceeds the miter limit.
Bevel Specifies a beveled join. This produces a diagonal corner.
Round Specifies a circular join. This produces a smooth, circular arc between the lines.
MiterClipped Specifies a mitered join. This produces a sharp corner or a beveled corner, depending on whether the length of the miter exceeds the miter limit.
Olovka.LineJoin LineJoin.Bevel
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DashStyle 
Member Description
Solid Specifies a solid line.
Dash Specifies a line consisting of dashes.
Dot Specifies a line consisting of dots.
DashDot Specifies a line consisting of a repeating pattern of dash-dot.
DashDotDot Specifies a line consisting of a repeating pattern of dash-dot-dot.
Custom Specifies a user-defined custom dash style.
Olovka.DashStyle DashStyle.DashDot
Pen Olovka  new Pen(Color.Black, 10)float Nas
aIsprekLinija   5.0f, 2.0f, 1.0f, 3.0fOlovka
.DashPattern   NasaIsprekLinija
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Drawing basic shapes

• To draw lines with Windows GDI you need to
• create a Graphics object and a Pen object.
• The Graphics object provides the methods that
• actually do the drawing, and the Pen object
  stores
• attributes of the line, such as color, width, and
  
• style.

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Basic shapes

• Lines
• Rectangles
• Ellipses
• Arcs
• Pies
• Polygons
• Cardinal Splines
• Bézier Splines
• Paths
• Open and Closed Curves
• Regions
• Clipping

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Lines
public void DrawLine(Pen pen, Point pt1, Point
pt2 ) Pen Type System.Drawing.Pen Pen that
determines the color, width, and style of the
line. Pt1 Type System.Drawing.Point Point struc
ture that represents the first point to
connect.   Pt2 Type System.Drawing.Point Point 
structure that represents the second point to
connect. 
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Lines

• g.DrawLine(new Pen(Color.Red, 3.2f), 0, 0, 250,
  250)
• Point PocetnaTacka new Point(0,0)
• Point KrajnjaTacka new Point(250,50)
• Pen Olovka new Pen(Color.GreenYellow, 3.2f)
• g.DrawLine(Olovka, PocetnaTacka, KrajnjaTacka)

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Rectangles

• public void DrawRectangle( Pen pen, Rectangle
  rect )
• Pen
• Type System.Drawing.PenA Pen that determines
  the color, width, and style of the rectangle. 
• Rect
• Type System.Drawing.RectangleA Rectangle struct
  ure that represents the rectangle to draw. 

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Rectangles

• g.DrawRectangle(new Pen(Color.Blue, 2.5f), 50,
  50, 150, 100)
• g.DrawRectangle(new Pen(Color.Blue, 2.5f), new
  Rectangle(50, 50, 100, 50))

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Elipses

• public void DrawEllipse( Pen pen, Rectangle rect
  )
• Pen
• Type System.Drawing.PenA Pen that determines
  the color, width, and style of the rectangle. 
• Rect
• Type System.Drawing.RectangleA Rectangle struct
  ure that represents the rectangle to draw. 

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Ellipses

• g.DrawEllipse(new Pen(Color.Black, 3), 50, 50,
  150, 100)
• g.DrawEllipse(new Pen(Color.Blue, 2.5f), new
  Rectangle(50, 50, 100, 50))

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Arcs

• g.DrawArc(new Pen(Color.Black, 3), 50, 50, 150,
  100, 0, 140)

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Pies

• Graphics g e.Graphics
• Matrix matricaTransformacija new Matrix(1, 0,
  0, -1, 0, 0)
• matricaTransformacija.Translate(this.ClientRectang
  le.Width / 2, -this.ClientRectangle.Height / 2)
• g.Transform matricaTransformacija
• g.DrawLine(new Pen(Color.Black),
  -this.ClientRectangle.Width / 2, 0,
  this.ClientRectangle.Width / 2, 0)
• g.DrawLine(new Pen(Color.Black), 0,
  this.ClientRectangle.Height / 2, 0,
  -this.ClientRectangle.Height / 2)
• Pen Olovka new Pen(Color.FromName("red"), 3)
• g.DrawPie(Olovka, -100, -100, 200, 200, 0, 300)

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Pies
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Polygons

• Point tacke new Point
• new Point(100, 25),
• new Point(25, 100),
• new Point(150, 200),
• new Point(275, 100),
• new Point(200, 25)
• Pen Olovka new Pen(Color.Black, 3)
• g.DrawPolygon(Olovka, tacke)

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Cardinal Bézier Splines
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Bézier Splines
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Paths

• Paths are formed by combining lines, rectangles,
  and simple curves.
• Lines
• Rectangles
• Ellipses
• Arcs
• Polygons
• Cardinal splines
• Bézier splines

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Paths

• GraphicsPath gp new GraphicsPath(FillMode.Altern
  ate)
• //gp.AddPolygon(tacke)
• gp.AddLine(50, 150, 50, 350)
• gp.AddLine(50, 350, 250, 350)
• gp.AddArc(250, 250, 400, 200, 180, -180)
• gp.AddLine(650, 350, 850, 350)
• gp.AddLine(850, 350, 850, 150)
• gp.AddLine(850, 150, 650, 150)
• gp.Ad,dArc(250, 50, 400, 200, 0, -180)
• //gp.CloseFigure()
• gp.AddLine(250, 150, 50, 150)
• gp.AddRectangle(new Rectangle(300, 200, 300,
  100))

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Paths

• g.FillPath(new SolidBrush(Color.Yellow), gp)
• g.DrawPath(Olovka, gp)

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Brushes

• To fill a closed shape, you need
  a Graphics object and a Brushobject.
• Solid Brushes
• Hatch Brushes
• Texture Brushes
• Gradient Brushes

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Solid Brushes

• public SolidBrush( Color color )
• color
• Type System.Drawing.ColorA Color structure
  that represents the color of this brush. 

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Solid Brushes
g.Clear(Color.Black) SolidBrush CetkaR new
SolidBrush(Color.FromArgb(128, 255, 0,
0)) SolidBrush CetkaG new SolidBrush(Color.From
Argb(128, 0, 255, 0)) SolidBrush CetkaB new
SolidBrush(Color.FromArgb(128, 0, 0,
255)) g.FillEllipse(CetkaR, 50, 50, 300,
300) g.FillEllipse(CetkaG, 250, 50, 300,
300) g.FillEllipse(CetkaB, 150, 200, 300, 300)
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Hatch Brushes

• public HatchBrush( HatchStyle hatchstyle, Color
  foreColor, Color backColor )
• hatchstyle
• Type System.Drawing.Drawing2D.HatchStyleOne of
  the HatchStyle values that represents the pattern
  drawn by this HatchBrush. 
• foreColor
• Type System.Drawing.ColorThe Color structure
  that represents the color of lines drawn by
  this HatchBrush. 
• backColor
• Type System.Drawing.ColorThe Color structure
  that represents the color of spaces between the
  lines drawn by this HatchBrush. 

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Hatch Brushes
g.Clear(Color.White) HatchBrush Cetka new
HatchBrush(HatchStyle.Cross, Color.Green) HatchBr
ush Cetka1 new HatchBrush(HatchStyle.Cross,
Color.Black, Color.Red) HatchBrush Cetka2 new
HatchBrush(HatchStyle.Divot, Color.Yellow,
Color.Blue) g.FillEllipse(Cetka, 50, 50, 300,
300) g.FillEllipse(Cetka1, 250, 50, 300,
300) g.FillEllipse(Cetka2, 150, 200, 300, 300)
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Texture Brushes
g.Clear(Color.White) Image slika
Image.FromFile("C\\Documents and
Settings\\Ognjen\\Desktop\\RG\\slike\\texture__.j
pg") Image slika1 Image.FromFile("C\\Documents
and Settings\\Ognjen\\Desktop\\RG\\slike\\Y-Yell
owTexture.bmp") Image slika2
Image.FromFile("newwall.bmp")
TextureBrush Cetka new TextureBrush(slika) Tex
tureBrush Cetka1 new TextureBrush(slika1) Textu
reBrush Cetka2 new TextureBrush(slika2)