C # GDI + drawing

1 coordinate system

(1) Coordinate origin: in the upper-left corner of the form or control, the coordinates are (0,0)

(2) Positive direction: the positive direction of the x-axis is horizontal to the right, the y-axis positive direction is vertical downward

(3) Units: In the setting, generally in pixels, pixels (Pixel) are composed of images (picture) and elements (element), is used to calculate the digital image of a unit.

By enlarging the image several times, you will find that these successive tones are actually composed of many small square dots of similar color, which are the smallest units of pixels that make up the image.

The quality of the graph is determined by the pixel, the larger the pixel, the greater the resolution.

2 Namespace---system.drawing

(1) System.Drawing provides access to the basic graphics features of GDI +

(2) Common basic class and structure of System.Drawing

Class	Description
Bitmap	An object that is used to process images with pixel data definitions.
Brush	Defines the inner object used to fill the shape of a graphic.
Font	Defines a specific text format.
Graphics	Encapsulates a GDI + drawing and cannot inherit this class.
Pen	Objects that are used to draw lines and curves cannot inherit this class.
Region	Indicates the interior of a shape that is composed of rectangles and paths that cannot inherit this class.
Color	Represents the RGB color.
Point	Defines a point defined in a two-dimensional plane.
Rectangle	Stores a set of 4 integers, representing the position and size of a rectangle.
Size	Stores an ordered integer pair, usually the width and height of a rectangle.

3 Graphics class

The graphics class encapsulates a GDI + drawing interface that provides methods for drawing objects to the display interface. When you create a graphical image using GDI +, you need to create a graphics object, that is, where to draw.

There are 3 different types of drawing interfaces:

(1) Forms and controls

(2) Printer

(3) Bitmap for memory

To create a graphical object in the 3 method:

(1) OnPaint () method parameter of the control class PaintEventArgs get the Graphics object

(2) The CreateGraphics () method in the form class or control class obtains the Graphics object

(3) Produce a graphics object from a Bitmap object (BITMAP)

Common methods of the Graphics class

Name	Description
Dispose	Releases all resources used by the graphics.
DrawEllipse	Draws an ellipse, with height, width, and pair of coordinates.
DrawArc	Draw arcs.
DrawLine	Draws a line, specified by 2 points.
DrawPolygon	Draws a polygon defined by a set of point structures.
DrawRectangle	Draws a rectangle.
Drawpie	Draw a fan.
Drawcurse	Draws the curve, specified by the parameter point array.
FillEllipse	Fills the interior of the ellipse defined by the bounding rectangle.
FillRegion	Fills the interior of the region.
ScaleTransform	Applies the scaled action you have made to the secondary graphics.
Tanslatetransform	Pan changes the origin of the coordinate system.

4 Drawing Tool Classes

Class name	Description
Pen	Sets the brush's color, line weight, and line style (solid and dashed).
Brush	Used to fill the shape, set the brush's style, color, and the thickness of the line.

5 derived classes of the brush class

Name	Description
ImageBrush	The image drawing area.
LinearGradientBrush	Linear gradient drawing area.
RadialGradientBrush	The radial gradient drawing area, where the focus defines the beginning of the gradient, and the ellipse defines the end point of the gradient.
SolidColorBrush	A monochrome paint area.
VideoBrush	The area where the video content is drawn.

6 Cases Free http://download.csdn.net/detail/taoerit/8350869

7 Code

Using system;using system.collections.generic;using system.componentmodel;using system.data;using System.Drawing;    Using system.linq;using system.text;using system.windows.forms;using system.drawing.drawing2d;namespace GDI drawing {        Public partial class Maindialog:form {public Maindialog () {InitializeComponent (); private void Maindialog_load (object sender, EventArgs e) {} private void Linebutton_click (o Bject sender, EventArgs e) {//Draw straight Graphics gra = this.            CreateGraphics ();            Pen pen = new Pen (color.red); Pen.            Width = 2;            Point startPoint = new Point (20,20);            Point endPoint = new Point (70,20); Gra.                        DrawLine (Pen,startpoint,endpoint); Pen.            Dispose (); Gra.        Dispose (); private void Rectanglebutton_click (object sender, EventArgs e) {//Draw rectangle Graphics GRA = this. CreateGraphics ();            Pen pen = new Pen (color.red); Gra.            DrawRectangle (pen, 20, 50, 100,100); Pen.            Dispose (); Gra.        Dispose ();            } private void Cyliderbutton_click (object sender, EventArgs e) {//cylinder, with many ellipses having a bottom gradually stacked up, and the last fill color int height = this.            clientsize.height-150; int width = this.            clientsize.width-50;            int vheight = 200;            int vwidth = 100; Graphics gra = this.            CreateGraphics (); Gra.            Clear (Color.White);            Pen pen = new Pen (color.gray,2);            SolidBrush brush = new SolidBrush (Color.gainsboro); for (int i = HEIGHT/2; i > 0;i--) {gra.            DrawEllipse (Pen,width/2,i,vheight,vwidth); } gra.        FillEllipse (Brush,width/2,0,vheight,vwidth); private void Fillrectanglebutton_click (object sender, EventArgs e) {//Draw rectangle Graphics GRA = this.            CreateGraphics (); Pen PEn = new Pen (color.red,3); Brush brush = Pen.            Brush;            Rectangle rect = new Rectangle (20,50,100,100); Gra.            FillRectangle (Brush,rect); Gra.        Dispose (); private void Drawellispebutton_click (object sender, EventArgs e) {Graphics gra = this.            CreateGraphics ();            Rectangle rect = new Rectangle (0,0,200,100);            LinearGradientBrush brush = new LinearGradientBrush (rect,color.orange,color.purple,90); Gra.            FillEllipse (Brush,rect); Gra.        Dispose (); private void Fontbutton_click (object sender, EventArgs e) {Graphics gra = this.            CreateGraphics ();            Font font = new Font ("script", 24,fontstyle.italic);            Pen pen = new Pen (color.blue,3); Gra. DrawString ("Windows application Design", Font,pen.        BRUSH,10,100);  private void Ellispebutton_click (object sender, EventArgs e) {//draw round Graphics gra = This. CreateGraphics ();            Pen pen = new Pen (color.red); Gra.            DrawEllipse (pen, 0, 0, 200,100); Pen.            Dispose (); Gra.        Dispose (); private void Moveellispebutton_click (object sender, EventArgs e) {//move round Graphics GRA = this.            CreateGraphics ();            Pen pen = new Pen (color.red); Gra. TranslateTransform (10,10);//Change the coordinates (10,10) gra.            DrawEllipse (pen, 0, 0, 200, 100); Gra.        Dispose (); private void Scaleellispebutton_click (object sender, EventArgs e) {//zoom round float XS            Cale = 1.5F;            float Yscale = 2F; Graphics gra = this.            CreateGraphics ();            Pen pen = new Pen (color.red); Gra. ScaleTransform (XScale, Yscale);//x-axis magnification 1.5 times times, y-axis magnification twice times gra.            DrawEllipse (pen, 0, 0, 200, 100); Gra.        Dispose (); private void Curvebutton_click (object sender, EventArgs e) {//Draw curve GraphicsGRA = this.            CreateGraphics ();            Pen pen = new Pen (color.blue,3); Point oo1 = new Point (30,this.            CLIENTSIZE.HEIGHT-100); Point oo2 = new Point (this. CLIENTSIZE.WIDTH-50, this.            CLIENTSIZE.HEIGHT-100); Gra.            DrawLine (PEN,OO1,OO2);            Point Oo3 = new Point (30, 30); Gra.            DrawLine (pen, oo1, Oo3);            Font font = new System.Drawing.Font ("Arial", 12,fontstyle.bold); Gra. DrawString ("X", Font,pen.            BRUSH,OO2); Gra. DrawString ("Y", Font,pen.            brush,10,10);            int x1 = 0, x2 = 0;            Double A = 0; Double y1 = 0, y2 = this.            clientsize.height-100; for (x2 = 0; x2 < this. clientsize.width;x2++) {a = 2 * Math.PI * X2/(this).                Clientsize.width);                y2 = Math.sin (a); y2 = (1-y2) * (this.                CLIENTSIZE.HEIGHT-100)/2; Gra.                DrawLine (pen,x1 +30, (float) Y1, x2+30, (float) y2);                x1 = x2;        y1 = y2;    } gra.        Dispose (); } private void Piechartbutton_click (object sender, EventArgs e) {//pie chart Graphics GRA = This.            CreateGraphics ();            Pen pen = new Pen (color.blue, 3);            Rectangle rect = new Rectangle (50,50,200,100);            Brush brush = new SolidBrush (Color.Blue); Gra. FillPie (pen.            BRUSH,RECT,0,60); Gra.            FillPie (brush,rect,60,150);            Brush = new SolidBrush (color.yellow); Gra.        FillPie (brush,rect,210,150); }    }}

C # GDI + drawing