2.2.3The Toolbox window

Finally, we are ready to insert the controls onto the form. In future chapters, we will not include the excruciating details of adding controls to forms and setting their properties with the Forms Designer, so make sure you understand the process here.

If you recall, in chapter 1 we inserted a Button and a PictureBox on our form. We will do the same here using Visual Studio.

ADD THE CONTROLS TO OUR FORM

ADD THE CONTROLS TO OUR FORM (continued)

Our controls are now on the form. Each control is named based on the type of control. The Button is called button1, while the PictureBox is called pictureBox1. Visual Studio .NET automatically creates a name for each new control based on the class name followed by a number. A second Button object added to the form would be called button2, and so forth. As for the Form1 class earlier in this chapter, we would prefer more descriptive names for our controls, so we rename these items in the following table.

In addition, we need to set the properties for our controls similar to the settings in chapter 1. Since we have set our control’s position and size graphically, there is no need to assign the positional properties such as Left and Height here. In chapter 1, we also set the Text property of the button to “&Load” and the BorderStyle property of the PictureBox control to Fixed3D.

Visual Studio provides a special Properties window where the properties and name of a control can be viewed and modified. We can use these to update our controls. We will set the Button properties first by continuing our previous steps.

RENAME THE CONTROLS AND DEFINE THEIR PROPERTIES

RENAME THE CONTROLS AND DEFINE THEIR PROPERTIES

Before we compile and run this code, let’s check out the MainForm.cs source code generated by Visual Studio .NET to see how this code has changed in response to our actions. Take a look at the region marked Windows Form Designer generated code in the source file. You may need to click the plus (+) sign in front of this region to display this block of code. This region defines the InitializeComponent method where properties and other settings are defined. Your code should look something like this:

#region Windows Form Designer generated code

///<summary>

///Required method for Designer support - do not modify

///the contents of this method with the code editor.

///</summary>

this.pbxPhoto.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;

layout logic

}

#endregion

A couple of points here are worth highlighting. The numbers from the previous code excerpt match the numbers in the following list.

bAs we saw in chapter 1, control variables are classes and therefore represent reference types. In order to create an actual object for each control, the new keyword is used.

this.btnLoad = new System.Windows.Forms.Button();

this.pbxPhoto = new System.Windows.Forms.PictureBox();

cTo ensure that the .NET Framework does not attempt to lay out the form while it is being created, the normal layout logic is suspended to prevent layout-related activities and events from occurring. The SuspendLayout method is available to all Windows Forms controls for this purpose.

this.SuspendLayout();

dTo make the generated code easier to read and understand for both programmers and book authors, the settings for each control are defined in their own labeled section. The comments here indicate which control variable is configured by the subsequent code.

//

// btnLoad

//

eThe properties we set in the Windows Forms Designer are defined in each control’s section. The Name property is always set to the variable name of the control, while the TabIndex property is also set for each control, starting with zero (0), to establish the tab order for the controls on the form.

this.btnLoad.Name = "btnLoad";

this.btnLoad.TabIndex = 0;

this.btnLoad.Text = "&Load";

fThe size and location of each control is determined automatically by Visual Studio

.NET and defined here. The settings are defined using structures such as Point and Size from the System.Drawing namespace. A structure, unlike a class, is a value

type, so the new statement creates these objects on the stack and copies their value into the appropriate property.

this.pbxPhoto.Location = new System.Drawing.Point(40, 80);

. . .

this.pbxPhoto.Size = new System.Drawing.Size(216, 160);

. . .

this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);

this.ClientSize = new System.Drawing.Size(292, 273);

gOnce all of the controls are created and initialized, they can be added to the form. Visual Studio adds the controls in one statement using the AddRange method available to the Form.Controls property. Note how this method accepts an array of

Control objects. All Windows Forms controls are based on the Control class, as we shall see in chapter 4. Note the use of square brackets to declare the array type, with the elements for the Control[] array defined in the subsequent braces.2 The order of the controls in the array defines the initial z-order of the controls.

this.Controls.AddRange(new System.Windows.Forms.Control[] {

this.pbxPhoto,

this.btnLoad});

hAt the end of the InitializeComponent method, normal layout processing must be resumed. The ResumeLayout method accepts a boolean value indicating whether an immediate layout should occur or not. For Visual Studio, an immediate layout is not necessary, so the method is invoked with false.

this.ResumeLayout(false);

2 For more details on declaring arrays in C#, see the discussion in appendix A.