GAMBAS BOOK 3.19.1

The Rect (gb.clipper) class represents a rectangle with integer coordinates. This chapter presents the properties and methods of the Rect class as well as some examples for using the class.

The Rect class has these properties:

Table 25.2.4.1.1 : Properties of the Rect class

The methods for the Rect class are described here.

Table 25.2.4.2.1 : Methods of the Rect class

The Rect class can be created and used like a (static) function:

Dim hRect As Rect 
hRect = New Rect(100, 100, 300, 200)

In the next example, several rectangles and a point P are created and methods of the Point and Rect classes are used. The results of the operations with the rectangles and the point as operands are output or visualised in the console:

[1] Public Sub ScriptRectangles()
[2]   Dim PointP As Point
[3]   Dim RectRed, RectGreen, RectCopy, RectIntersection, RectUnion As Rect
[4]   
[5]   PointP = New Point(177, 144)
[6]   RectRed = New Rect(60, 60, 400, 180)
[7]   RectGreen = New Rect(130, 20, 90, 170)
[8]   RectIntersection = New Rect
[9]   RectUnion = New Rect
[10]     
[11]   Print "P in RectRed? --> "; RectRed.Contains(PointP.X, PointP.Y)
[12]   Print "P in RectRed? --> "; PointP.InRect(RectRed)  
[13]   Print "Cx = "; RectRed.Center().X; " , Cy = "; RectRed.Center().Y
[14]   RectCopy = RectRed.Copy()
[15]   Print "R3x = "; RectCopy.X; " , R3y = "; RectCopy.Y
[16]   RectCopy.Clear
[17]   
[18]   RectIntersection = RectRed.Intersection(RectGreen)
[19]   Print "RIx = "; RectIntersection.X; " , RIy = "; RectIntersection.Y
[20]   Print "RIW = "; RectIntersection.Width; " , RIH = "; RectIntersection.Height  
[21]   RectUnion = RectRed.Union(RectGreen)
[22]   Print "RIx = "; RectUnion.X; " , RIy = "; RectUnion.Y
[23]   Print "RIW = "; RectUnion.Width; " , RIH = "; RectUnion.Height
[24]   
[25]   GenerateNewPicture()
[26]   SetPictureBorder()  
[27]   Paint.Begin(hPicture)   
[28]     Paint.Translate(xTranslate, yTranslate)
[29]     Paint.Scale(xScale, yScale) ' +y ▲
[30]     Paint.AntiAlias = False
[31]     DrawCoordinateSystem() ' +y ▲      
[32] '-- Original coordinate system --> +y-direction downwards
[33] '-- Red rectangle  
[34]     Paint.Brush = Paint.Color(Color.Red)
[35]     Paint.Rectangle(RectRed.X, RectRed.Y, RectRed.W, RectRed.H)
[36]     Paint.Fill(True)    
[37]     Paint.Brush = Paint.Color(Color.DarkGray)
[38]     Paint.LineWidth = 2
[39]     Paint.Stroke()
[40] '-- Green rectangle
[41]     Paint.Brush = Paint.Color(Color.Green)
[42]     Paint.Rectangle(RectGreen.X, RectGreen.Y, RectGreen.W, RectGreen.H)
[43]     Paint.Fill(True)    
[44]     Paint.Brush = Paint.Color(Color.DarkGray)
[45]     Paint.LineWidth = 2
[46]     Paint.Stroke()
[47] '-- Blue rectangle (intersection)
[48]     Paint.Brush = Paint.Color(Color.Blue)
[49]     Paint.Rectangle(RectIntersection.X, RectIntersection.Y, RectIntersection.W, RectIntersection.H)
[50]     Paint.Fill(True)    
[51]     Paint.Brush = Paint.Color(Color.DarkGray)
[52]     Paint.LineWidth = 2
[53]     Paint.Stroke()      
[54] '-- Bordered rectangle (union - union set) 
[55]     Paint.Brush = Paint.Color(Color.Magenta)
[56]     Paint.Rectangle(RectUnion.X, RectUnion.Y, RectUnion.W, RectUnion.H)
[57]     Paint.Dash = [2, 2]
[58]       Paint.LineWidth = 2
[59]       Paint.Stroke()   
[60]     Paint.Dash = Null
[61]     Paint.FillRect(260, 150, 3, 3, Color.Black) ' Mittelpunkt C einzeichnen
[62] '-- Label the centre point C of the diagonal in the red rectangle
[63]     Paint.Scale(1, -1) ' +y ▼
[64]       Paint.Font = Font["Monospace, 10"]      
[65]       Paint.Brush = Paint.Color(Color.Black)
[66]       Paint.DrawText("C(260|150)", 270, -145)
[67]       Paint.Font = Font["Monospace, 8"]
[68]     Paint.Scale(1, -1) ' +y ▲
[69]   Paint.End()
[70]   
[71] End  

These results are displayed in the console in the IDE:

P in RectRed? --> True
P in RectRed? --> True
Cx = 260 , Cy = 150
R3x = 60 , R3y = 60
RIx = 130 , RIy = 60
RIW = 90 , RIH = 130
RIx = 60 , RIy = 20
RIW = 400 , RIH = 220

In the following illustration, you can also read these results with sufficient accuracy:

Figure 25.2.4.3.1: Mutual position of the rectangles RectRed and RectGreen

Lines 48 to 61 also show the two rectangles (blue and with a dashed magenta border) that were created in lines 18 and 22 when using the methods Rect.Intersection(..) and Rect.Union(..) from the two rectangles RectRed and RectGreen:

Figure 25.2.4.3.2: Created rectangles: Rect.Intersection(..) and Rect.Union(..)

While only integers are permitted as coordinates for the Rect class, you can use real numbers for the coordinates X and Y as well as for the width and height for the RectF class.