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Scroll Bars

Scroll Bars. Providing Scrollbars. Objectives. You will be able to: Use Windows Graphics to display tabular information on a Windows form. Add graphics capability to objects. Provide scroll bars on a Windows form. Object Oriented Drawing and Printing.

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Scroll Bars

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  1. Scroll Bars Providing Scrollbars

  2. Objectives You will be able to: • Use Windows Graphics to display tabular information on a Windows form. • Add graphics capability to objects. • Provide scroll bars on a Windows form.

  3. Object Oriented Drawing and Printing • In an object oriented program, everything that appears on the screen should be the visual representation of an object. • Objects should know how to draw themselves. • Printing is essentially the same.

  4. Schedule Grid • Let’s modify the Schedule Viewer program to use Windows graphics instead of the DataGridView. • We will teach the Schedule_Record class how to draw itself.

  5. Schedule Grid • In order for schedule entries to fit on one line with legible type, display only: • Course Number • Section • Course Title • Days • Time • Building • Room

  6. Menu • Provide a File menu with commands: • Open • Print • Exit • Use the common dialog for Open. • Menu commands should be enabled only when relevant. • Enable Print only when there is something to print. • Disable Open once a file is open.

  7. Scroll Bars • Provide scroll bars to permit the user to view all of the schedule when it doesn’t fit in the window. • The scroll bars should not be visible if the schedule fits in the window.

  8. Start with Schedule Viewer Example • Download the example • http://www.cse.usf.edu/~turnerr/Software_Systems_Development/Downloads/2011_02_22_Schedule_Viewer_2/ • File Schedule_Viewer.zip • Also the schedule data files • schedule_2010_fall.csv • schedule_2010_spring.csv • schedule_2011_spring.csv

  9. Getting Started • Be sure we have a known Starting Point • Expand and build the project. • Verify that the program works.

  10. Out with the old! • Delete the DataGridView. • Keep the menu strip and openFileDialog.

  11. Stripped Down Project

  12. Out with the old! • View the code for Form1.cs • Delete all of the DataGridView code. • Lines 86 - 99 (Most of openToolSTripMenuItem_Click) • Lines 63 - 78 (Most of Form1 constructor ) • Keep file and menu related functions • Build. Verify that project compiles.

  13. In With the New! • Add some member variables to Form1 using System.Drawing; ... public partial class Form1 : Form { List<Schedule_Record> Schedule; // Graphics information Font Font1 = new Font("Arial", 10); Brush Brush1 = SystemBrushes.WindowText; // Screen information const int Top_Margin = 30; const int Bottom_Margin = 30; const int Left_Margin = 20;

  14. Add Graphics • Add Output method to class Schedule_Record. • Initially make it a stub • Just output “Schedule Entry” public void Output(Graphics G, Font F, Brush B, Point P) { Pen pen = new Pen(Color.Black, 1); G.DrawString("Schedule Entry", F, B, P); } • Will need using System.Drawing;

  15. Add a Paint Event Handler to Form1 private void Form1_Paint(object sender, PaintEventArgs e) { int y_pos = Top_Margin; if ((Schedule == null) || (Schedule.Count == 0)) { return; } for (int i = 0; i < Schedule.Count; i++) { Point P = new Point(Left_Margin, y_pos); Schedule[i].Output(e.Graphics, Font1, Brush1, P); y_pos += Font1.Height; } }

  16. Open private void openToolStripMenuItem_Click(object sender, EventArgs e) { Import_Schedule(); this.Invalidate(); this.Update(); } In Form1.cs Build and run.

  17. Program Running

  18. Teaching the Schedule Record to Output Itself • A Schedule Record object should know how to draw itself on the screen or a printed page. • But it must be told: • Where to draw itself. • The drawing objects to use: • Graphics • Font • Brush • Download: • http://www.cse.usf.edu/~turnerr/Software_Systems_Development/Downloads/2011_03_22_Scroll_Bars/Output.cs

  19. Implement Schedule_Record Output() public void Output(Graphics G, Font F, Brush B, Point P) { Pen pen = new Pen(Color.Black, 1); int X_Pos = P.X; int Y_Pos = P.Y; Rectangle R = new Rectangle(X_Pos, Y_Pos, 75, F.Height); G.DrawString(course_number, F, B, R); G.DrawRectangle(pen, R); X_Pos += R.Width; R = new Rectangle(X_Pos, Y_Pos, 40, F.Height); G.DrawString(section.ToString(), F, B, R); G.DrawRectangle(pen, R); X_Pos += R.Width; R = new Rectangle(X_Pos, Y_Pos, 250, F.Height); G.DrawString(course_title, F, B, R); G.DrawRectangle(pen, R); X_Pos += R.Width;

  20. Schedule_Record Output() R = new Rectangle(X_Pos, Y_Pos, 75, F.Height); G.DrawString(days, F, B, R); G.DrawRectangle(pen, R); X_Pos += R.Width; R = new Rectangle(X_Pos, Y_Pos, 160, F.Height); G.DrawString(time, F, B, R); G.DrawRectangle(pen, R); X_Pos += R.Width; R = new Rectangle(X_Pos, Y_Pos, 40, F.Height); G.DrawString(building, F, B, R); G.DrawRectangle(pen, R); X_Pos += R.Width; R = new Rectangle(X_Pos, Y_Pos, 60, F.Height); G.DrawString(room, F, B, R); G.DrawRectangle(pen, R); X_Pos += R.Width; }

  21. Program Running Note that the schedule runs off the page.

  22. Scroll Bars • Let’s add scroll bars. • The Form object will do most of the work for us. • For documentation search for autoscroll in Visual Studio Help.

  23. Autoscroll To get automatic scrollling we must: • Set the Autoscroll property to True. • Set AutoScrollMinSize property • Scroll bars will be added if form is smaller. • Data dependent! • Adjust X and Y coordinates for output to account for scrolling: • AutoScrollPosition.X; • AutoScrollPosition.Y;

  24. In Schedule_Record.cs In class definition: private static int line_width = 500; public static int Line_width { get { return line_width; } } At end of function Output() line_width = X_Pos;

  25. Form1_Paint At top of function: if ((Schedule == null) || (Schedule.Count < 1)) { return; } int Document_Length = Schedule.Count * Font1.Height + Top_Margin + Bottom_Margin; int line_width = Schedule_Record.Line_width; this.AutoScrollMinSize = new Size(Left_Margin + line_width, Document_Length); int dx = this.AutoScrollPosition.X; int dy = this.AutoScrollPosition.Y; ... Point P = new Point(Left_Margin + dx, y_pos + dy);

  26. We have scroll bars!

  27. Just One Problem • The menu scrolls off the screen! • Need to scroll just the area below the menu. • How?

  28. Saving the Menu • Put a Panel below the menu • Fill rest of form • Draw on the Panel rather than the form. • Scroll the panel.

  29. Form with Panel

  30. Configure the Panel • Position and size the panel to fill the form below the menu strip. • Anchor it on all sides.

  31. Configure the Panel

  32. Drawing on the Panel • Now we need to draw on the panel rather than the form. • Set AutoScroll true. • Add a Paint event handler for the panel. • Move the contents of Form1_Paint to panel1_Paint.

  33. Scrolling the Panel • Change the scrolling information from form1 to panel1. • In openToolStripMenuItem_Click () ... this.panel1.Invalidate(); this.panel1.Update(); • In panel1_Paint () ... this.panel1.AutoScrollMinSize = new Size(Schedule_Record.Line_Width, Document_Length); int dx = this.panel1.AutoScrollPosition.X; int dy = this.panel1.AutoScrollPosition.Y;

  34. Program Running

  35. Some Finishing Touches • Change panel1 BackColor to white. • Add a bit of space below the panel. • Set the Text property of Form1 • CSE Schedule

  36. Some Finishing Touches

  37. Program Running

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