GDI programming 10 basic skills
Create a drawing surface
There are two common methods for creating a drawing surface. Try Now to get the drawing surface of the Picturebox.
Private Void Form1_Load (Object Sender, System.EventArgs E)
{
/ / Get drawing surface of Picturebox1
Graphics g = this.picturebox1.creategraphics ();
}
Private void PictureBox1_paint (Object Sender, System.Windows E), PRAINTERGS E)
{
/ / Get drawing surface of Picturebox1
Graphics g = E.Graphics;
}
Various graphics patterns can be drawn using Graphics objects. The Paint events of the control and the onpaint method can be drawn. The pattern is drawn in the onPaint method must have a Graphics property from the parameter e. Here are two examples.
Protected Override Void Onpaint (Painteventargs E)
{
E.Graphics.clear (color.white);
Float X, Y, W, H;
X = this.Left 2;
Y = this.top 2;
W = this.width-4;
H = this.height-4;
Pen Pen = New Pen (Color.Red, 2);
E.Graphics.drawRectangle (Pen, X, Y, W, H);
Base.onpaint (e);
}
Private Void PictureBoxii_Resize (Object Sender, Eventargs E)
{
THIS.INVALIDATE ();
}
Private void Button1_Click (Object Sender, System.Eventargs E)
{
This.PictureBoxii1.createGraphics (). Fillellipse
Brushes.blue, 10, 20, 50, 100);
}
Three classes related to text:
FontFamily - defines a similar basic design but has some of the forms of differences in the form. Unable to inherit this class.
Font - defines a specific text format, including fonts, font numbers, and glyph properties. Unable to inherit this class.
StringFormat - Package text layout information (such as alignment and line spacing), display operation (such as omitted number insertion and national standard) and OpenType functionality. Unable to inherit this class.
The following program shows a paragraph.
Private void button2_click (Object Sender, System.Eventargs E)
{
Graphics g = this.pictureboxi1.creategraphics ();
g.fillRectangle (Brushes.White, this.PictureBoxii1.clientRectangle);
String s = "aaaaaaaaaaaaaaaaaaaaaaaaa";
Fontfamily fm = new fontfamily ("ëîìå");
Font f = new font (fm, 20, fontstyle.bold, graphicsunit.point);
Rectanglef Rectf = New Rectanglef (30, 20, 180, 205);
StringFormat sf = new stringFormat ();
Solidbrush Sbrush = New Solidbrush (Color.Fromargb (255, 0, 0, 255)); sf.LineAlignment = StringAlignment.Center;
sf.formatflags = stringFormatflags.directionVertical;
g.drawstring (S, F, Sbrush, RectF, sf);
}
GDI path - GraphicsPath class
The GraphicsPath class provides a range of attributes and methods that use it to get the key points on the path, which can add a straight segment, round and other geometric elements. Enclosed rectangles can be obtained to pick up test. How to use these features, take a closer look.
Private void button3_click (Object Sender, System.Eventargs E)
{
// Draw surface
Graphics g = this.pictureboxi1.creategraphics ();
// Fill in white
g.fillRectangle (Brushes.White, this.clientRectangle);
// Get a drawing path
Graphicspath gp = new graphicspath ();
// Add some collection graphics
GP.Addellipse (20, 20, 300, 200);
GP.Addpie (50, 100, 300, 100, 45, 200);
GP.AddRectangle (New Rectangle (100, 30, 100, 80));
// Draw a drawing path on the drawing surface
g.drawpath (Pens.Blue, GP);
// Translation
G.TranslateTransform (200, 20);
// Fill the drawing path
g.fillpath (brushes.greenyellow, gp);
gp.dispose ();
}
Area-Agion class
You can create region from existing rectangles and paths. Draw the Region using the Graphics.FillRegion method. This class indicates the inside of the graphical shape made of rectangles and by the path. Unable to inherit this class.
Gradient filling
Two brushes need to be used:
Linear gradient brush (lineargradientbrush)
Path Gradient Brush (PathguadientBrush)
Private void button4_click (Object Sender, System.Eventargs E)
{
// Draw surface
Graphics g = this.pictureboxi1.creategraphics ();
g.fillRectangle (Brushes.White, this.PictureBoxii1.clientRectangle);
/ / Define a linear gradient brush
Lineargradientbrush LGBrush =
New lineargradientbrush
New Point (0, 10),
New Point (150, 10),
Color.Fromargb (255, 0, 0),
Color.Fromargb (0, 255, 0));
Pen Pen = New Pen (LGBRUSH);
// Draw a straight segment and fill a rectangle with a pen brush gradient effect
g.drawline (Pen, 10, 130, 500, 130);
G.FillRectangle (LGBrush, 10, 150, 370, 30);
/ / Define the path and add an ellipse
Graphicspath gp = new graphicspath ();
GP.Addellipse (10, 10, 200, 100);
// Define the path gradient brush with this path
PathGradientBrush Brush =
NEW PATHGRADIENTBRUSH (GP); // Color array
Color [] colors = {
Color.Fromargb (255, 0, 0),
Color.Fromargb (100, 100, 100),
Color.Fromargb (0, 255, 0),
Color.Fromargb (0, 0, 255)};
/ / Define color gradient ratio
Float [] r = {0.0F, 0.3F, 0.6F, 1.0F};
Colorblend Blend = New Colorblend ();
Blend.colors = colors;
Blend.positions = r;
Brush.interpolationcolors = blend;
// Fill a rectangle outside the ellipse
G.FillRectangle (Brush, 0, 0, 210, 110);
// Define the second path gradient brush with the path added to the ellipse
Graphicspath gp2 = new graphicspath ();
GP2.Addellipse (300, 0, 200, 100);
PathGradientbrush brush2 = new pathgradientbrush (gp2);
/ / Set the center point position and color
Brush2.centerpoint = new pointf (450, 50);
Brush2.centercolor = color.fromargb (0, 255, 0);
// Set the border color
Color [] color2 = {color.fromargb (255, 0, 0)};
Brush2.ssurroundcolors = color2;
// Fill the ellipse with the second gradient
g.fillellipse (Brush2, 300, 0, 200, 100);
}
GDI coordinate system
General coordinate system - User-defined coordinate system.
Page Coordinate System - Virtual Coordinate System.
Equipment coordinate system - screen coordinate system.
When the unit of the page coordinate system and device coordinate system is pixel, they are the same.
Private void button10_click (Object Sender, System.EventArgs E)
{
Graphics g = this.pictureboxi1.creategraphics ();
g.clear (color.white);
THIS.DRAW (g);
}
Private Void Draw (Graphics G)
{
g.drawline (Pens.Black, 10, 10, 100, 100);
g.drawellipse (Pens.black, 50, 50, 200, 100);
g.drawarc (Pens.Black, 100, 10, 100, 100, 20, 160);
g.drawRectangle (Pens.green, 50, 200, 150, 100);
}
Private void button5_click (Object Sender, System.Eventargs E)
{
// Left shift
Graphics g = this.pictureboxi1.creategraphics ();
g.clear (color.white);
G.TranslateTransform (-50, 0);
THIS.DRAW (g);
}
Private void button6_click (Object Sender, System.Eventargs E)
{
// right movement
Graphics g = this.pictureboxi1.creategraphics ();
g.clear (color.white);
G.TranslateTransform (50, 0);
THIS.DRAW (g);
}
Private void Button7_click (Object Sender, System.Eventargs E) {
// Rotate
Graphics g = this.pictureboxi1.creategraphics ();
g.clear (color.white);
G.RotateTransform (-30);
THIS.DRAW (g);
}
Private void button8_click (Object Sender, System.EventArgs E)
{
//enlarge
Graphics g = this.pictureboxi1.creategraphics ();
g.clear (color.white);
G.scaletransform (1.2F, 1.2F);
THIS.DRAW (g);
}
Private void button9_click (Object Sender, System.Eventargs E)
{
/ / Reduce
Graphics g = this.pictureboxi1.creategraphics ();
g.clear (color.white);
G.scaletransform (0.8F, 0.8F);
THIS.DRAW (g);
}
Global Coordinates - Transforms will have an impact on each of the drawings. Usually used to set a universal coordinate system.
The program moves to the center to the center of the control, and the Y axis is forwarded.
// Painting a circle
Graphics g = E.Graphics;
g.fillRectangle (Brushes.White, this.clientRectangle);
g.drawellipse (Pens.Black, -100, -100, 200, 200);
// Make the Y axis to the top, must do a relative to X-axis mirroring
/ / The transformation matrix is [1, 0, 0, -1, 0]
Matrix Mat = New Matrix (1, 0, 0, -1, 0, 0);
g.Transform = Mat;
Rectangle Rect = this.clientRectangle;
INT w = Rect.width;
INT H = Rect.height;
G.TranslateTransform (W / 2, -H / 2);
/ / Take the origin as the center, make a circle having a radius of 100
g.drawellipse (Pens.Red, -100, -100, 200, 200);
G.TranslateTransform (100, 100);
g.drawellipse (Pens.green, -100, -100, 200, 200);
G.scaletransform (2, 2);
g.drawellipse (Pens.Blue, -100, -100, 200, 200);
Local coordinate system - transforms only some graphics, while other graphical elements are unchanged.
Protected Override Void Onpaint (Painteventargs E)
{
Graphics g = E.Graphics;
/ / The client area is set to white
g.fillRectangle (Brushes.White, this.clientRectangle);
// Y axis
Matrix Mat = New Matrix (1, 0, 0, -1, 0, 0);
g.Transform = Mat;
// Mobile coordinate original to the center
Rectangle Rect = this.clientRectangle;
INT w = Rect.width;
INT H = Rect.height;
G.TranslateTransform (W / 2, -H / 2);
// Draw an ellipse under global coordinates
g.drawellipse (Pens.Red, -100, -100, 200, 200); g.fillRectangle (brushes.black, -108, 0, 8, 8);
G.fillRectangle (Brushes.black, 100, 0, 8, 8);
G.FillRectangle (Brushes.black, 0, 100, 8, 8);
g.fillRectangle (Brushes.black, 0, -108, 8, 8);
// Create an ellipse and then transform in the local coordinate system
Graphicspath gp = new graphicspath ();
GP.Addellipse (-100, -100, 200, 200);
Matrix mat2 = new matrix ();
// Translation
Mat2.translate (150, 150);
// Rotate
Mat2.Rotate (30);
GP.TRANSFORM (MAT2);
g.drawpath (Pens.Blue, GP);
POINTF [] P = gp.pathpoints;
g.fillRectangle (Brushes.black, P [0] .x-2, p [0] .y 2, 4, 4);
G.FillRectangle (Brushes.Black, P [3] .x-2, p [3] .y 2, 4, 4);
G.fillRectangle (brushes.black, p [6]. x-4, p [6]. Y-4, 4, 4);
G.fillRectangle (brushes.black, p [9]. x-4, p [9] .y-4, 4, 4);
gp.dispose ();
//base.onpaint (e);
}
Alpha mix
The color.fromargb () is Alpha. The value of Alpha is fully transparent from 0 to 255.0, and 255 is completely opaque.
Current color = foreground color × alpha / 255 background color × (255-alpha) / 255
Protected Override Void Onpaint (Painteventargs E)
{
Graphics g = E.Graphics;
// Create a fill rectangle
Solidbrush brush = new solidbrush (color.blueviolet);
G. FillRectangle (Brush, 180, 70, 200, 150);
// Create a bitmap, there is a transparent effect between two bitmaps
Bitmap BM1 = New Bitmap (200, 100);
Graphics bg1 = graphics.fromimage (bm1);
Solidbrush redbrush =
New Solidbrush (Color.Fromargb (210, 255, 0, 0);
Solidbrush Greenbrush =
New Solidbrush (Color.Fromargb (210, 0, 25, 0));
BG1.FillRectangle (Redbrush, 0, 0, 150, 70);
BG1.FillRectangle (Greenbrush, 30, 30, 150, 70);
G. DrawImage (BM1, 100, 100);
// Create a bitmap, there is no transparent effect between the two bitmaps
Bitmap BM2 = New Bitmap (200, 100);
Graphics bg2 = graphics.fromimage (bm2);
Bg2.compositingmode = compositingmode.sourcecopy;
Bg2.fillRectangle (Redbrush, 0, 0, 150, 170); Bg2.FillRectangle (Greenbrush, 30, 30, 150, 70);
g.CompositingQuality = compositingquality.gammacorred;
g.drawImage (BM2, 300, 200);
//base.onpaint (e);
}
Go away
Protected Override Void Onpaint (Painteventargs E)
{
Graphics g = E.Graphics;
// Zoom 8 times
G.scaletransform (8, 8);
/ / No refused to go to the graphics and text
DRAW (g);
// Set the reverse
g.smoothingmode = smoothingmode.antialias;
// Right shift 40
G.TranslateTransform (40, 0);
// Draw it again after it is afraid.
DRAW (g);
//base.onpaint (e);
}
Private Void Draw (Graphics G)
{
// Draw graphics and text
g.drawline (Pens.gray, 10, 10, 40, 20);
g.drawellipse (Pens.gray, 20, 20, 30, 10);
String s = "Reverse Walking Test";
Font font = new font ("Song", 5);
Solidbrush Brush = New Solidbrush (Color.gray);
g.drawstring (S, Font, Brush, 10, 40);
}
Finished. Said to make so much first. It will be supplemented in the future.
