1. Self Study GUI Properties & Events
CS1S467 GUI Programming
Self Study
GUI Properties & Events

2. Visual Studio Controls
(Button, CheckBox, Label,…)
Properties
(colour, position, visible,…)
Events
(clicked, dragged, changed,…)

3. Changing Properties/Events
Via Visual Studio GUI (simple to do)
Controls
(Button, CheckBox, Label,…)
Properties
(colour, position, visible,…)
Events
(clicked, dragged, changed,…)
Programmatically (a bit more tricky)

4. PART 1: Properties

5. Changing Properties Programmatically
Simple
OiO Constructors
OiO Properties
3 Groups of Properties
Simple, direct (e.g. ProgressBar value > int, Button visible > boolean)
Using Object-in-Object Constructors (fonts, points)
Using Object-in-Object Properties (colour, text position)

6. Changing Properties Programmatically
Simple
OiO Constructors
OiO Properties
Copying a Boolean Property
Setting directly
private void visible_cBx _CheckedChanged(object sender, EventArgs e) {
button1.Visible = visible_cBx.Checked; }
button1.Visible = true;
button1.Visible = false;

7. Changing Properties Programmatically
Simple
OiO Constructors
OiO Properties
Using Object-in-Object Constructors
GUI Controls are made from many sub-objects (lines, areas, fonts, …)
Constructors create new objects (note the keyword 'new')
These new objects can then be used to replace existing objects (e.g. an old font by a new font)

8. Changing Properties Programmatically
Simple
OiO Constructors
OiO Properties
Using Object-in-Object Constructors (here: the 'Font' constructor)
private void bold_cBx_CheckedChanged(object sender, EventArgs e) {
if (bold_cBx.Checked)
button1.Font = new Font(button1.Font.Name, button1.Font.Size+4, FontStyle.Bold); }
else
button1.Font = new Font(button1.Font.Name, button1.Font.Size-4 ,FontStyle.Regular);

9. Changing Properties Programmatically
Simple
OiO Constructors
OiO Properties
Using Object-in-Object Constructors (here: the 'Point' constructor)
private void xPos_UpDown_ValueChanged(object sender, EventArgs e) {
button1.Location = new Point( (int) xPos_UpDown.Value, 77); }

10. Changing Properties Programmatically
Simple
OiO Constructors
OiO Properties
Using Object-in-Object Properties (here: properties of the 'Color' class)
private void backColour_comboBx_SelectedIndexChanged(object sender, EventArgs e) {
if (backColour_comboBx.SelectedIndex == 0) button1.BackColor = Color.Red;
if (backColour_comboBx.SelectedIndex == 1) button1.BackColor = Color.Green;
if (backColour_comboBx.SelectedIndex == 2) button1.BackColor = Color.Blue; }

11. Changing Properties Programmatically
Simple
OiO Constructors
OiO Properties
Copying Object-in-Object Properties
private void textColourBtn_Click(object sender, EventArgs e) {
// Show the colour dialog.
DialogResult result = colorDialog1.ShowDialog();
// See if user pressed ok or cancel.
if (result == DialogResult.OK)
// Set button text colour to the selected color.
button1.ForeColor = colorDialog1.Color; }
Although dragged onto Form …
…….… it will appear here

12. Changing Properties Programmatically
Simple
OiO Constructors
OiO Properties
Using Object-in-Object Properties (here: properties of the 'ContentAlignment' class)
private void radioButton1_CheckedChanged(object sender, EventArgs e) {
button1.TextAlign = ContentAlignment.BottomLeft; }
private void radioButton2_CheckedChanged(object sender, EventArgs e)
button1.TextAlign = ContentAlignment.MiddleCenter;
private void radioButton3_CheckedChanged(object sender, EventArgs e)
button1.TextAlign = ContentAlignment.TopRight;

13. PART 2: Events

14. Control Events When double-clicking on a Control
the default event handler method stub will be created:
private void button1_Click(object sender, EventArgs e) { }
once an event handler has been created you can't change the control name any more without an unwanted side effect:
control name changes
event handler name doesn't
private void button1_Click(..

15. Control Events Therefore
Give EVERY control a MEANINGFUL name immediately after creation:
private void SortButton_Click(object sender, EventArgs e) { }

16. Control Events When double-clicking on a Control
usually the 'Click' event handler gets created:
but not always:
private void button1_Click(object sender, EventArgs e) { }
private void maskedTextBox1_MaskInputRejected(object sender, MaskInputRejected… e) { }

17. Control Events To set other Event Handlers
double-click on the correct event
private void maskedTextBox1_ModifiedChanged(object sender, EventArgs e) { }

18. Drag Event Handling Controls Events Form1 label1 label2 MouseDown
MouseMove
MouseUp

19. Drag Event Handling
private Point MouseDownLocation; // stores starting X and Y position
private void label1_MouseDown(object sender, MouseEventArgs e) {
if (e.Button == System.Windows.Forms.MouseButtons.Left)
MouseDownLocation = e.Location;
Cursor.Current = Cursors.Hand; }
private void label1_MouseMove(object sender, MouseEventArgs e)
label1.Left = e.X + label1.Left - MouseDownLocation.X;
label1.Top = e.Y + label1.Top - MouseDownLocation.Y;
label2.Text = "Dragging";
private void label1_MouseUp(object sender, MouseEventArgs e)
label2.Text = "Dropped";