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Windows Programming Form Programming II

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Contents

Boxes-ListBox, ComboBox

Menus

TreeView

TabControl

Layout

MessageBox

File

Drawing

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ListBox

The ListBox presents a list of items which can be

selected

A scrollbar is displayed if needed

MultiColumn – displays list as multiple columns

SelectedIndex – index of selected item

SelectedItem – the selected item

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ListBox

SelectedItems – collection of selected items

SelectionMode – how items can be selected

None – no selection

One – single selection

MultiSimple – each click selects additional item

MultiExtended – uses shift and control keys

Sorted – if true the items will be sorted alphabetically

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ListBox

Items – a collection of items in the list box

* see ListBoxDemo

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Populating a ListBox

Any object can be placed into a ListBox

The display is generated by ToString()

for(int i = 0; i < 50; i++) {

listBox1.Items.Add(

"Item " + i.ToString());

}

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ComboBox

A combo box is like a list but lets you displays a selected value.

The list pulls down when a selection is being made.

Options allow the selected text to be editable or to require it to be selected from the drop-down list

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ComboBox

DropDownStyle –

Simple – text is editable & list always visible

DropDown – default indicating text is editable

& user must click to see list

DropDownList – value is not editable & user

must click to see list

Items – the collection of items in the list

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ComboBox

MaxDropDownItems – max number of items in pulldown before scrollbar used

SelectedIndex – index of selection

SelectedItem – selected item

Sorted – whether entries are sorted

SelectedIndexChanged – event raised when selection changes

* see ComboBoxDemo

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Menus

Pulldown menus provide a way to select commands

and options

Normally these are in a MenuStrip across the top of

the application

Begin by placing a MenuStrip across the application

It displays boxes into which menu items and

cascading menus can be typed

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Menus

The type here text allows

new items to be added

When you click on type

here a pull down appears

letting you select

Menu item

ComboBox

Separator

TextBox

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MenuItem Properties

Checked – if true displays check mark

CheckOnClick – check state changes when clicked

CheckState – one of

CheckState.Checked

CheckState.Unchecked

CheckState.Indeterminate

ShortcutKeys – a member of the Shortcut enumeration indicating the shortcut key

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MenuItem

Click – event which is raised when the menu item is clicked

Menu items are similar to buttons and are handled in the same way

* see MenuDemo

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ComboBox Menu Items

You can use a ComboBox as a menu item

Use the designer to add a set of Items to the combo box

You can then select a value

The click event is raised only when you click on the selected value, not when you change the selection

If you have nothing selected, the selected item will be null

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TreeView

Presents a hierarchical tree view of the data

Nodes can be

Selected

Expanded and collapsed

Text of nodes can be edited

Nodes can be added or deleted programmatically

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TreeView

This is the actual control

Properties

Nodes – get TreeNodeCollection of all children of this node

CheckBoxes – if true, displays checkboxes beside tree nodes

SelectedNode – the selected node

LabelEdit – if true, node text can be edited

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TreeView

Events

AfterSelect – after a node is selected

AfterExpanded – after a node is expanded

AfterCollapsed – after a node is collapsed

AfterEdited – after a node is edited

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Populating a TreeView

1. Usually, create a root TreeNode

2. Add the root node onto the Nodes collection of the TreeView

3. Create a child TreeNode and add it to the Nodes collection of the root node

4. Continue this way to build whole tree

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TreeViewEventArg

The signature for an event handler is

void EventHandler(object sender, EventArgs e)

TreeView events use a subclass called

TreeViewEventArg

Properties

Node – the node where the event originated

You will have to use the Node member to find which

tree node is affected by some events

* see TreeViewDemo 20

TabControl

Displays a series of tabs

Each tab is a different page with its own controls on it

Each tab is like a group box or panel

Create

In Visual Studio

Drop controls into the tab pages

Set the text property of every page to change the label

Right click on a tab and select “Add Tab” to add a new tab

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TabControl

Multiline – if true tabs can be in several lines

SelectedIndex – index of selected tab

SelectedTab – the selected tab

TabPages – collection of TabPages

SelectedIndexChanged – event raised when a

different tab is selected

* see TabDemo

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Automatic Layout

All of the forms we have seen so far have been laid out based on X-Y coordinates

If the outer form is resized, the contents stay at the same size and position

There are three ways to change this

The Dock property

The FlowLayoutPanel

The TableLayoutPanel

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The Dock Property

Every control has a Dock property which can be set to

None – no docking

Left – docked to left side of container

Right – docked to right side of container

Top – docked to top of container

Bottom – docked to bottom of container

Fill – fills all available space

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The Dock Property

When controls are docked to the

sides of their containing form,

resizing the form resizes the

controls inside as well

* see DockDemo

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FlowLayoutPanel

Arranges its contents into horizontal

or vertical rows

As form is resized, controls are

arranged into new rows or columns

Created in designer by dropping

controls into it

In designer it has small arrow on the

top that activates menu of editing

actions

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FlowLayoutPanel

FlowDirection – layout direction

BottomUp

TopDown

LeftToRight

RightToLeft

WrapContents – whether the contents should be

wrapped to a new row or column or clipped

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TableLayoutPanel

Arranges the controls within it into rows and columns

Automatically resizes contents when the surrounding form is resized

The pull-out menu in designer can be used to add or delete rows and columns

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TableLayoutPanel

ColumnCount – get/set number of columns

RowCount – get/set number of rows

* see LayoutDemo

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MessageBox

A pop-up dialog which displays a message

Use the static Show methods to see one

DialogResult Show(string) – box with simple string and OK button

DialogResult Show(string text, string caption)

DialogResult Show(string text, string caption, MessageBoxButtons)

OK

OKCancel

RetryCancel

YesNo

YesNoCancel

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DialogResult

Abort

Cancel

Ignore

No

None

OK

Retry

Yes

*See DialogDemo; Calculator(NetCalc

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Files & Directories

This section will explore how to work with files and

directories

We begin with directories

Directory

Contains static methods for creating, deleting, moving and listing

directories

DirectoryInfo

An instance represents a directory

Has instance methods for manipulating the directory 32

Directory Class

Method Description

CreateDirectory( )

Creates all directories and subdirectories specified by its

path parameter.

GetCreationTime() Returns and sets the time the specified directory was

created.

GetDirectories() Gets named directories.

GetLogicalDrives() Returns the names of all the logical drives in the form

<drive>:\.

GetFiles() Returns the names of files matching a pattern.

GetParent() Returns the parent directory for the specified path.

Move() Moves a directory and its contents to a specified path.

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Directory Class

Method Description

Delete( ) Deletes a directory.

Exists() Determines if a directory exists.

GetFiles() Returns the names of files in a specified directory.

GetCurrentDirectory() Returns the path of the current directory.

GetLastAccessTime() Returns the last time file was accessed.

GetLastWriteTime() Returns the last time file was written.

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DirectoryInfoClass

Method Description

Attributes

Inherits from FileSystemInfo; gets or sets the

attributes of the current file.

CreationTime gets or sets the creation time of the current file.

Exists true if the directory exists.

Extension The File Extension

FullName the full path of the file or directory.

Name The directory name.

Root Root portion of the path.

Parent Parent Directory

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DirectoryInfo Class

Method Description

Create() Creates the directory if it does not exist.

CreateSubdirectory() Creates a subdirectory.

Delete() Deletes the directory.

GetDirectories() Returns an array of DirectoryInfo objects.

GetFiles() Returns an array of FileInfo objects.

MoveTo() Relocates the directory and its contents.

Refresh() Refreshes the directory list.

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A File Lister string curDirName = Directory.GetCurrentDirectory();

DirectoryInfo curInfo = new DirectoryInfo(curDirName);

Console.WriteLine("Listing for {0}", curInfo.FullName);

DirectoryInfo[] dlist = curInfo.GetDirectories();

foreach (DirectoryInfo d in dlist) {

Console.WriteLine("{0}\t\t{1}", d.Name, d.LastWriteTime);

}

FileInfo[] flist = curInfo.GetFiles();

foreach (FileInfo f in flist) {

Console.WriteLine("{0}\t\t{1}", f.Name, f.LastWriteTime);

}

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Working with Files

Two classes are provided to deal with files

File

A collection of static methods to manipulate files

FileInfo

Instance methods to manipulate a single file

These classes are analogous to the two directory classes

They add the ability to read and write files

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Reading and Writing Files

Files can be read and written in two ways

Binary

Binary data is written to a file

Fast, efficient, not human readable

Suited for writing data structures

Text

Converts bytes to a specific character encoding

Slower than binary

Can be read by humans

* See CreatefileDemo, readsequentialaccessfile, fileTest

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Stream Class

The Stream class is used to read and write binary data

from and to a file

Read methods

int Read(byte[] buf, int offset, int count)

Reads up to count bytes into buf at offset

Return the number of bytes read or zero at EOF

int ReadByte()

Reads one byte

Returns -1 at EOF 40

Stream Class

Write methods

void Write(byte[] buf, int offset, int count)

void WriteByte(byte);

void Flush();

Direct Access Methods

long Seek(long offset,seekOrigin);

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SeekOrigin

An enumeration with values indicating where a seek should be from

Begin, Current, End

Seeking moves the read/write pointer through a file and determines where the next read or write will occur

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StreamReader Class

This reads a file by converting the bytes to characters

int Read()

Reads the next char, returns -1 on EOF

int Read(char[] buf, int offset, int count)

Reads up to count chars into buf at offset

Return 0 at EOF

string ReadLine()

Reads the next line

Returns null on EOF

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StreamWriter Class

Used to write text files

void Write(char)

void Write(char[])

void Write(string)

Void Flush()

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Buffered Streams

Read and writing a byte at a time is painfully slow

It is much more efficient to read and write a buffer full at a time

The BufferedStream class does just that

It works just like a stream

Just wrap it around your stream

BufferedStream bs = new

BufferedStream(stream);

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Opening Binary Streams

Open one stream for reading and one for writing

Use the static methods of the File class

Stream OpenRead(string path);

Stream OpenWrite(string path);

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Reading and Writing Text Files

To create a file for writing

StreamWriter sw = new

StreamWriter("MyFile.txt");

To open a file for reading

FileInfo fi = new

FileInfo("MyFile.txt");

StreamReader sr = fi.OpenText();

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Reading and Writing Text Files

The following example

Checks to see if a file exists

If it does not, it opens the file for writing and

writes some content

It then opens the file for reading and writes the

contents to the console

It then closes the file

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Drawing

So far, we have used controls to draw everything on the screen

There is a lower-level interface which can be used to draw anything into a form

Using this we can

Handle any type of event

Draw anything

Create our own controls

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Coordinates

All windows have their own coordinate

space with the origin in the top-left

corner

X values increase to the right

Y values increase downward

Coordinates are usually expressed as an

integer number of pixels

(0,0) X

Y

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Measurement Units

Pixel is the default unit but others can be used

Graphics has a property PageUnit which is a member of the enum GraphicsUnit

Display – device units: pixels for monitors & 1/100 inch for printers

Document – 1/300 inch

Inch – inch

Millimeter – millimeter

Pixel – (default) pixel

Point – 1/72 inch

World – world coordinates

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Drawing

We have already see the Color and Font classes

To draw we are also interested in

Pen – the width & color of a line

Brush – the fill for a figure like a rectangle

SolidBrush – a solid color

TextureBrush – a pattern

Graphics – a class containing drawing methods

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Pen

A drawing object used to specify the color and width of a line

Constructor

Pen(Color, int width)

Pen(Brush, int width)

Properties

DashStyle – for dashed lines, one of

Solid

Dash

DashDot

DashDotDot

Dot

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SolidBrush

A color used to fill the interior of a closed figure

Constructor

SolidBrush(Color)

Properties

Color – get/set the brush color

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Graphics

The graphics object is associated with a drawing surface and provides methods to draw on that surface

The graphics object is given to you by the framework, you do not create it

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Graphics

Clear(Color) – clears the entire surface with the color

DrawArc(Pen, int x, int y, int ht, int

wd, int startAngle, int endAngle) – draw an arc of an ellipse contained by the rectangle

DrawEllipse(Pen, int x, int y, int ht,

int wd) – draw an ellipse within the rectangle

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Graphics

DrawLine(Pen, Point, Point) – draw a line between two points

DrawPie(Pen, int x, int y, int

ht, int wd) – draw an pie slice within the rectangle

DrawRectangle(Pen, int x, int y,

int ht, int wd) – draw a rectangle

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Graphics

DrawString(string, Font, Brush, single

x, single y) – draw a string at the point

FillMethods

Most of the draw methods have equivalent Fill methods

The Fill methods draw a solid figure rather than an outline

They use a brush rather than a pen

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Event Handling

When you create your own control which draws you can

Add event handlers as we have done in the past

Override the methods for handling these events in the parent class

Often, it is easier to override the methods in the

parent class to make behaviour inheritable

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Event Handling Methods

void OnMouseDown(MouseEventArgs e)

void OnMouseUp(MouseEventArgs e)

void OnMouseMove(MouseEventArgs e)

void OnMouseWheel(MouseEventArgs e)

void OnKeyDown(KeyEventArgs e)

OnKeyUp(KeyEventArgs e)

void OnResize(EventArgs e)

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MouseEventArgs

Button – get button pressed

Clicks – get the number of times the button was pushed and released

Delta – number of positions mouse wheel rotated

X – mouse coordinate

Y – mouse coordinate

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Painting

Forms are painted by calling OnPaint(Graphics

g)

You override this method to paint whatever you need

You NEVER call this method

You call Invalidate() when you want to be

repainted and the windowing system calls

OnPaint() for you

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Overriding Methods

When you override a method, your method is called, not the one in the parent class

However, the one in the parent class often does something important

Therefore, always call the method in the base class before doing your own thing

* see WinDraw