ToolboxBitmapAttribute in C#.NET

Generating QR Code in C#.NET ToolboxBitmapAttribute

Of these classes, you will use Graphics the most often because it provides methods for drawing to the display device. The Pen class is used to draw lines and curves, while classes derived from the abstract class Brush are used to fill the interiors of shapes. Additionally, you should be familiar with the PictureBox class, which you can use in Windows Forms applications to display an image as part of the user interface. The System.Drawing namespace includes the structures shown in Table 6-2.

Table 6-2

Description Specifies a range of character positions within a string. Represents a color. Represents an ordered pair of integer x and y coordinates that defines a point in a two-dimensional plane.

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Table 6-2

Description Represents an ordered pair of floating point x and y coordinates that defines a point in a two-dimensional plane. Stores a set of four integers that represent the location and size of a rectangle. For more advanced region functions, use a Region object. Stores a set of four floating-point numbers that represent the location and size of a rectangle. For more advanced region functions, use a Region object. Stores an ordered pair of integers, typically the width and height of a rectangle. Stores an ordered pair of floating-point numbers, typically the width and height of a rectangle.

The most important of these structures the structures you ll use most often are Color, Point, Rectangle, and Size.

One of the simplest and most common uses for the System.Drawing namespace is specifying the location of controls in a Windows Forms application. This process can be useful to create forms that dynamically adjust based on user input. To specify a control s location, create a new Point structure by specifying the coordinates relative to the upper-left corner of the form, and use the Point to set the control s Location property. The related PointF structure accepts coordinates as floating points, rather than integers, but PointF cannot be used to specify the location of GUI controls. For example, to move a button to the upper-left corner of a form, exactly 10 pixels from the top and left sides, you would use the following code:

' VB button1.Location = New Point(10, 10) // C# button1.Location = new Point(10, 10);

Most of this book relies on console applications for samples. However, this chapter uses Windows Forms applications to easily display graphics.

As an alternative to using Point, you could perform the same function using the Left and Top or Right and Bottom properties of a control. However, this requires two lines of code, as the following example illustrates:

' VB button1.Left = 10 button1.Top = 10 // C# button1.Left = 10; button1.Top = 10;

You can specify the size of a control just as simply as you specify the location. The following code demonstrates how to specify the size using the Size class:

' VB button1.Size = New Size(30, 30) // C# button1.Size = new Size(30, 30);

You can specify a control s color using the Color structure. The simplest way to specify a color is to use one of the predefined properties located within System.Drawing.Color, as the following example demonstrates:

' VB Button1.ForeColor = Color.Red Button1.BackColor = Color.Blue // C# button1.ForeColor = Color.Red; button1.BackColor = Color.Blue;

If you need to specify a custom color, use the static Color.FromArgb method. The method has several overloads, so you can specify the color by using a single byte, by specifying the red, green, and blue levels, or by using other information.

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The following example illustrates how to specify color by providing three integers, for red, green, and blue:

' VB Button1.ForeColor = Color.FromArgb(10, 200, 200) Button1.BackColor = Color.FromArgb(200, 5, 5) // C# button1.ForeColor = Color.FromArgb(10, 200, 200); button1.BackColor = Color.FromArgb(200, 5, 5);