Introduction to computing
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A short presentation to get you started working with Visual Basic .NET and using Visual Studio creating a simple windows form application.
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Introduction to computing
- 2. AS Computing Unit F452
- 3. Building Applications ◦ Creating computer applications in Visual Studio ◦ Creating program code using VB.NET ◦ Testing Code (when it goes wrong!)
- 4. First thing you need to do in every Computing class is open Visual Studio. It can take a while so be patient…
- 6. You will create a ‘Windows Form Application’ that will allow you to choose and view a picture in the window that your program runs in. Follow the instructions on the following slides to produce your first program!
- 7. TOOLBOX PROJECT / SOLUTION EXPLORER DESIGN WINDOW OBJECT PROPERTIES CODE VIEW
- 8. Requirements: ◦ To choose an image file ◦ To show the chosen image file as a picture in a window of a program ◦ To be able to quit/close the program when required
- 9. File ◦ New Windows Form Application Give it the name ‘Picture Viewer’
- 10. Go to the Properties Window ◦ Find Form 1 > Text ◦ Change the ‘Text’ property from ‘Form1’ to ‘Picture Viewer’ Click the Save icon at the top! (do this quite often to prevent losing work) Change the Form Size ◦ Form Properties > Size Height > 500 Width > 350
- 11. Double-click to add objects: ◦ Add a ‘Button’ from the Toolbox with properties: Name – btnSelectPicture Location – 295,10 (x and y coordinates!) Size - 85,23 Text - Select Picture
- 12. Right click on the button, then copy, then paste within the form This will be the ‘Quit’ Button with properties: Name – btnQuit Location – 295,40 Text - Quit
- 13. Back to the Toolbox Double click on ‘PictureBox’ This need the following properties: Name – picShowPicture BorderStyle - FixedSingle Location – 8,8 SAVE!!!
- 14. Toolbox ◦ Double-click OpenFileDialog (in Dialogs category) ◦ Note that it is hidden at the bottom! Select OpenFileDialog and set properties: ◦ Name - ofdSelectPicture ◦ Filename - (leave this bit blank) ◦ Filter - Windows Bitmaps|*.BMP|JPEG Files|*.JPG ◦ Title - Select Picture
- 15. Double-click on the ‘Select Picture’ button ◦ Now you can add code to make it do stuff! Enter the code from the following slides
- 16. ' Show the open file dialog box If ofdSelectPicture.ShowDialog = DialogResult.OK Then ' Load the picture into the picture box picShowPicture.Image = Image.FromFile(ofdSelectPicture.FileName) ' Show the name of the file in the form's caption Me.Text = "Picture Viewer(" & ofdSelectPicture.FileName & ")" End If
- 17. ' Close the window and exit the application Me.Close()
- 18. Click SAVE! Click the green RUN (triangle) button at the top in the main toolbar Try choosing a picture! Click ‘Quit’ to close your program
- 19. 1. What type of VB program creates a standard Windows program? 2. What window is used to change attributes of a form or control in the IDE? 3. How do you access the code of a control? 4. What property of a picture box do you set to display an image? 5. What is the default event for a button control?
- 20. 1. Windows Form Application 2. Properties Window 3. Double-click an object in design view 4. The IMAGE property 5. The CLICK event
Editor's Notes
- #4: Software – instructions and data which enable the hardware to perform useful tasks.Event Driven – VB code is associated with objects and each object has a set of events assoc with it.Events are actions which VB detects and responds to. E.g. a user clicks on a button on a form (demo SIMS), that will generate a click event for that button i.e. what happens when the button is pressed. When an event is generated, VB will run any code (INSTRUCTIONS) that you have entered for that event.
- #15: Text entered into the Title bar appears in the open file dialog box that opens later
- #16: Clicking on a button is called an event. The code that you put in the button is called an event handler, ie it tells the program the instructions to carry out once the button is clicked.
- #17: Finished code: Private Sub btnSelectPicture_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSelectPicture.Click ' Show the open file dialog box. If ofdSelectPicture.ShowDialog = DialogResult.OK Then ' Load the picture into the picture box. picShowPicture.Image = Image.FromFile(ofdSelectPicture.FileName) ' Show the name of the file in the form's caption. Me.Text = "Picture Viewer(" & ofdSelectPicture.FileName & ")" End If End SubComments in green
- #18: Finished code: Private Sub btnQuit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnQuit.Click ' Close the window and exit the application Me.Close() End SubComments in green
- #19: Finished code: Private Sub btnQuit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnQuit.Click ' Close the window and exit the application Me.Close() End SubComments in green