Don Kussee -60 1410_appendix1 Simple Text Editor Don Kussee

Don Kussee -60 1410_appendix 1

Simple Text Editor

Don Kussee


TextBox Properties

• MultiLine = T ‘displays more than one line

• Text ‘string containing all the current text

• When there is highlighted text then– SelLength ‘ contains the number of characters– SelStart ‘contains the number of characters

from the start of the TextBox– SelText ‘contains the highlighted text

• If no selected text, then SelText = “”, SelLength = 0


Example 1

15 = Text1.SelLength19 = Text1.SelStartVAX text editor = Text1.SelText


Example 2

0 = Text1.SelLength17 = Text1.SelStart“” = Text1.SelText


Example 3

32 = Text1.SelLength3 = Text1.SelStart“grew up using a VAX text editor.” = Text1.SelText


To Clear the TextBox

• Text1.Text = “”

• cmdCut.Enable = F

• cmdCopy.Enable = F


To cut text

• Highlight some text and enable Cut & Copy

• Private Sub cmdCut_Click

• Text2.Text = Text1.SelText

• Text1.SelText = “”

• cmdCut.Enable = F

• cmdCopy.Enable = F

• End Sub


Using a State chart

• Define every possible condition for the program in general terms– TextBox empty, Paste buffer empty– Len(TextBox >0) , Paste buffer empty– Len(TextBox>0), Paste Buffer.caption >0– Len(TextBox>0), SelText>0 ….

• Define what objects can do what for that state and write the code for some event


Or Using a State chart

• Define what the objects are, and what their conditions are required to be

• Cut Button – Enabled = T when SelText>0– Enabled = F when SelText =0

• txtEdit_MouseUp ‘the code goes here

• Paste, Copy, Clear, Exit


Menus

CSIS 1410

Don Kussee


Building Menus

• A menu for each form

• File Edit View Insert Format Help

• Can contain 4 levels maximum

• First level is displayed

• Other levels cascade down based on choices

• Can create Popup Menus


Menu Design Window


Menu Properties

• Caption shows up on form

• Name used in code

• Checked allows TF choice

• Enabled & Visible available

• Hotkeys using & letter

• Short cut keys (drop down key choices)

• Arrows to change levels and location


Popup Menu

• Different menus can be designed for each object - context sensitive

• Can be specified in any object_event code segment– Often associated with Mouse_Down

• Menu is defined using Menu design tool

• Can be copy of menu, or can be invisible

• Location and size can be specified


Popup Menus

Private Sub Form_MouseDown (Button As Integer, Shift As Integer, X As Single, Y As Single)

If Button = 2 Then

PopupMenu mnuFile

End If

End Sub


Common Dialog

CSIS 1410

Appendix F

Don Kussee


Common Dialog

• Add to tool box– Project|Components

1 Place control on form

• Control is hidden during run mode

2 Set defaults to be used

3 Set Flags to be used

4 Define which Common Dialog to use .Show


Common Dialog cdl

• File Open - ShowOpen

• File Save - ShowSave

• Font - ShowFont

• Color - ShowColor

• Printer - ShowPrinter

• Help - poor implementation. Ok for very small files, use another for big tasks.


Files Save As Common Dialog


File Open Common Dialog


Files Common Dialog

• User can specify file and path

• Allows changes of drives, directories using WIN95 system tools

• FileName Default path & file name

• Filter Which types of files


Font Common Dialog


Font Common Dialog

• FontName

• FontSize

• Color

• Flags

• Font Bold, Italic, Underline, Strikethru


Color Common Dialog


Color Common Dialog

• Either system colors using constants vbBlack

• Normal colors can be shown using RGB( ) or QBColor ( )

• Custom Color gives second window


Printer Common Dialog


Printer Common Dialog

• Identifies all printers on the system

• Allows you to designate where you will ship the job to (does not ship it, just sets the switches).– Copies– Pages – from to – All – Current only


Visual Basic

CSIS 1410

Don Kussee

Files.ppt

Appendix E


Files - Background

• Sequential - Records of non-equal length

• Random - Records of equal length

• Text Vs Binary - Binary only beneficial with lots of large numbers

• DataBase data storage - Large overhead, so poor for small amounts of data. Much data not in DataBases format


Text VS Binary

• Text – Each character takes one byte– Numbers translated into characters - each gets a

byte– All numbers are translated as they are read – Files can be read easily with DOS/windows

readers


Text Vs Binary

• Binary– Each byte is transferred without translation– Character takes one byte– Numbers are not treated as characters

• Each value requires memory size storage

• May use as much as 16 bytes per number

• Most save several bytes per number

– Not readable by DOS/windows


Sequential Files

• Text files

• Allow variable record length

• Most commonly used - text editors

• Like a tape recorder– Each must be read to find the next record– Can’t find 3 until you have read 1 & 2


Random Files

• Require fixed record length

• Much wasted internal space

• Can jump to the 5 record easy– If each was a length of 128 bytes– Seek (5 * 128) – Get FirstName, LName ‘ the read

• Open file For Random As 1 Len = 128


File Use - the code part

• Open the File

• Use the file– Input

• Input #, Line Input #, Get (Random)

– Output• Write # comma delimited, in quotes, newline• Print # space or newline delimited• Put (Random)

• Close the file


Sequential File Open Modes

• Input data from files into program– Opens file at the front

• Output data to files from program– Opens file at the front– Creates a file if none exists– Writes over current data

• Append data to file, – Opens file at the end – Creates a file if none found


File Open Modes

• Binary – Read-only, Write-only, Read and Write, Get &

Put used to access file– Creates file if it doesn’t exist

• Random – Read-only, Write-only, Read and Write– Creates file if it doesn’t exist


Network Operations

• Share.EXE must be installed – Read, Write, Read Write– Shared,

• Operations allowed by other processes – Lock Read – Lock Write– Lock Read Write


Open StatementOpen FilePath For Output As # 1

• Each file open at the same time gets a different number

• Max files open a system value (usually >50)

• FreeFile will generate the next open file number


Output Statements (usual)

Write #1, Form1.txtEdit.Text

Write #1, txtPasteBuffer.Text

• Saves the contents of the text box to the file in quotes, followed by an EOF

• Second Write would replace the EOF with a comma and save next text in quotes, followed by an EOF


File Use

• Output Input

• Print Line Input # or Input.– Writes display-formatted data to a sequential file. – Print #filenumber, [outputlist]

• Write Input– Writes data to a sequential file.– Write #filenumber, [outputlist]


Output Statements Print #1, Form1.PadText.Text

• , between items skips to next tab (14 places)

• ; between items puts them together (no space between them)

• Print #1, “ bananas ”, “apples”, “sauce”

• newline at the end of each statement

• Print #4, Spc(13) ‘would store 13 spaces

• Print #2, Tab(6) ‘tabs to 6 column

• Print #3, ‘outputs a blank line


Output StatementsWrite #1, names(index), “number”

• commas are between each item in the file

• “xxx” are around each string in the file

• a newline is inserted in the file after each statement


Input from file

• Reads data from an open sequential file and assigns the data to variables.Input #filenumber, varlist

Input #1, Form1.txtEdit.Text, txtPasteBuffer.Text

Line Input #1 puts into a string all data until EOL or EOF found


File pointer movement


File pointer movement as event procedure cmdThreeAtATime_Click executes


Close # 1

• DOS file system used

• Data to buffer, then later, buffer to drive when buffer is full or file is closed

• Sends all data in the buffer to the file

• Appends an EOF, Updates Fat Table

• Closes the file

• Close ‘closes all open files


Input Statements (usual)Input #1, Form1.PadText.Text

• must match data in file to data type in program

• for string variables, – first “ is ignored, everything else (, space) up to

“ goes in– if no “ then end is assumed for , space or EOL– blank lines are 0 length strings

• Error generated on EOF


Input Statements (usual)Input #1, ScrollBar1.value, x, y

• for numerical variables– first non-space is start of number– space, comma or EOL is end of number– if non number (letters) the value is 0– blank line is 0

• arrays not usable array element is useable


EOF at end of file

• Error generated on EOF

index = 0

Do While Not EOF(1)

Input #1, x(index)

index = index + 1

Loop

Close # 1


Other Input Statements

• Input$ – only for Input of Binary mode– Returns all characters, commas, carriage

returns, linefeeds leading spaces

• Line Input #– reads all characters (except carriage returns &

linefeeds) in a line into a String or Variant


File use - the visual part

• Must determine the – Drive– Path– File name

• Must exist (or error) for Open Input• Will be generated for Open Output, Append• Errors will occur if Drive, Path, File

unavailable


Path using standard VB

• Build an input form using – DriveListBox– DirListBox– FileListBox

• Concatenate the variables together into path

• Filename$=Drive1.drive + “:\”

• Filename$=Filename$ + Dir1.Path + “\”

• Filename$=Filename$ + File.Filename


Path using the Professional VB

• cdb.FileName contains the Path


Code for OpenItem_click( )

Sub OpenItem_Click( )

CMDialog1.ShowSave

Open CMDialog1.FileName For Output as #1

Write #1, Form1.PadText.Text

Close #1

End Sub


File Save & Open Filter

• Defines the filter patterns to be displayed in a combo box description1 | filter1 | description2 | filter2 |description3 | filter3

• Then the filter index defines the default pattern CMDialog.filter= “Icons|*.ico|Bitmaps|*.bmp”

• CMDialog.FilterIndex = 2


CMDialog1.Flag =

• Flags sets and returns miscellaneous settings

• CONSTANT.TXT has define many constants

• OFN_FILEMUSTEXIST defined as &H1000

• Name and path validation– &H1000 Asserts the file must exist– &H400 Returns if exe different from default– &H8 Forces the directory to the default directory– &H100 Invalid characters not accepted– &H800 Invalid path not accepted


CMDialog1.Flag =

• Read only setting or returns– &H4 Hides read only check box– &H1 Set Read only bit – &H8000 Asserts file is NOT read only OR Write

. Protected

• File protection or creation– &H2000 Prompt for creation if it does not exist– &H2 Confirm overwriting an existing file– &H4000 Ignore file sharing violation


CMDialog1.Flag =

• Misc..– &H200 File Name list allows multiple

selections– &H10 Display a Help button


Code for SaveItem_click( )

• Sub OpenItem_Click( )– On Error Resume Next– CMDialog1.CancelError = -1– CMDialog1.DialogTitle = “Save File”– CMDialog1.Filter = “Text Files | *.txt|All files|*.*”– CMDialog1.FilterIndex = 1– CMDialog1.DefaultExt = “*.TXT”– CMDialog1.Flags = OFN_CREATEPROMPT – Or OFN_OVERWRITEPROMPT


Load current values Color, Font

CMDialog1.FontName = PadText.FontName

CMDialog1.FontItalic = PadText.FontItalic

CMDialog1.FontStrikethru = PadText.FontStrikethru

CMDialog1.FontSize = PadText.FontSize

CMDialog1.FontUnderline = PadText.FontUnderline

CMDialog1.Color = PadText.Color

CMDialog1.Flags = CF_SCREENFONTS


Error Handling

Appendix F Page 616

Don Kussee

CSIS 1410


Error Handling

• Occurs with runtime errors

• Divide by zero

• Invalid input

• File Open, File Save– Directory or File missing– Disk Missing– Write protect or disk door open


Error trapping

• Establish a watch dog

• When the watch dog is triggered identify what to do– Continue the code anyway– Retry the code– Allow the user to intervene– Discontinue the program

• Return to the program or Exit


Error trapping

Private Sub object_event

On Error GoTo Apple ‘watch dog

VB code

End Sub

Apple: ‘ Label start of error handling code

VB Code that handles the error

End Sub ‘the error handling subroutine


Possible Error handling

• At the end of the error handling, at the end of the code

• Resume ‘reruns the error statement• Resume Next ‘starts at the next statement• Resume Label ‘Starts at a new location• Exit Sub ‘Dynamite out of subroutine• Exit Function ‘Escapes out of function


Error handling in functions

• IF a line of code calls a function1 which calls a function2 calls a function3

• An error in function3 looks up the chain for the closest On Error code

• Resume will restart the function1 call

• Best to turn off On Error if this is a problem

• On Error GoTo 0 turns off the watch dog


Some Trappable Errors

• 6 Overflow• 11 Division by Zero• 13 Type mismatch• 18 User interrupt• 52 Bad file name• 53 File not found• 54 Bad file mode• 55 File already open

• 57 Device I/O error• 58 File already exists• 59 Bad record length• 61 Disk full• 67 Too many files• 71 Disk not ready• 76 Path not found• 482 Printer error


Error Object

• Err.Number ‘contains the error number

• Err.Source ‘contains the object

• Err.Description ‘Cryptic error message

• Err.Clear ‘ Clears the error

• Err.Raise(number) ‘ Creates an error number for testing purposes

• On Error GoTo 0 ‘Turn off watch dog


Error line number

• Erl contains the line number

• Must number all the lines to make it useful, but that is the way Basic was written, and can still be done in VB

• Usually start with 100 and count by 10s to allow inserting code without renumbering

Documents

Don Kussee -60 1410_appendix1 Simple Text Editor Don Kussee