Windows Controls: The Rich Text Box
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Windows Controls: The Rich Text Box |
Introduction to the Rich Text
Description
Text is considered rich if it can display various characters or paragraphs in different styles and features that make it more attractive than a regular ASCII text. Such a text can have some of its sections in different colors. Its paragraphs can have customized attributes or arranged independent of each other.
Although you can create a complete rich but static text, the common use of a rich text is to let the user process most of the formatting.
Creating a Rich Text Control
To support a rich text, the .NET Framework provides the RichTextBox control that is implement from the RichTextBox class. Like TextBox, the RichTextBox class is based on TextBoxBase. Therefore, to have right text in an application, from the Common Controls section of the Toolbox, click RichTextBox and click the form.
To programmatically create rich text, declare a variable of type RichTextBox, use the new operator to allocate memory for it, and add it to the Controls collection of its parent. Here is an example:
using System;
using System.Drawing;
using System.Windows.Forms;
public class Exercise : System.Windows.Forms.Form
{
RichTextBox rchNote;
public Exercise()
{
InitializeComponent();
}
private void InitializeComponent()
{
rchNote = new RichTextBox();
Controls.Add(rchNote);
}
}
public class Program
{
static int Main()
{
System.Windows.Forms.Application.Run(new Exercise());
return 0;
}
}
Practical Learning: Starting a Rich Text Application
and click the form
and click the form
and click the form
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using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.IO; namespace Notice2 { public partial class Editor : Form { string CurrentFileName; public Editor() { InitializeComponent(); } private void Editor_Load(object sender, EventArgs e) { CurrentFileName = "<Not Allowed>"; rchEditor.Modified = false; } } }
private void mnuEditUndo_Click(object sender, EventArgs e)
{
rchEditor.Undo();
}
private void mnuEditRedo_Click(object sender, EventArgs e)
{
rchEditor.Redo();
}
private void mnuEditCut_Click(object sender, EventArgs e)
{
rchEditor.Cut();
}
private void mnuEditCopy_Click(object sender, EventArgs e)
{
rchEditor.Copy();
}
private void mnuEditPaste_Click(object sender, EventArgs e)
{
rchEditor.Paste();
}
private void mnuSelectAll_Click(object sender, EventArgs e)
{
rchEditor.SelectAll();
}
private void mnuFormatWordWrap_Click(object sender, EventArgs e)
{
rchEditor.WordWrap = true;
}
The Text of a Rich Text Box
Introduction
Like the other graphical Windows controls, the right text box uses the common characteristics such as the location, the size, the minimum size, the maximum size, the anchor, the docking, the font, the ability to be visible or hidden, the ability to be enabled or disabled, and the border style. Like the TextBox control, the rich text control inherits various characteristics from the TextBoxBase class, including the Text property, the Lines collection, the read-only attribute, the ability to select and manipulate text. The rich text box also shares various characteristics with the multi-line text box such as the Multiline property, the scroll bars, the word wrap, the ability to accept the Tab and the Enter keys. Here is an example:
private void InitializeComponent()
{
rchNote = new RichTextBox();
rchNote.Size = new Size(Width, Height);
rchNote.Multiline = true;
rchNote.ScrollBars = RichTextBoxScrollBars.Both;
rchNote.AcceptsTab = true;
rchNote.Font = new Font("Verdana", 10.0F);
string[] strLines =
{
"LeavingSydney",
"When we decided to leave, we knew we were " +
"making a hard decision. We had spent so much " +
"time this had become our new home. A few " +
"weeks or months before, we wanted to make " +
"Sydney our newly found settlement, a " +
"permanent place we could proudly call ours. " +
"It appeared that, unpredictably, fate had " +
"decided otherwise.",
"Author: Arthur D. Pale",
"Title: Stories Of My Life"
};
rchNote.Lines = strLines;
Controls.Add(rchNote);
}
}
Saving the Contents of a Rich Text Document
After creating and formatting a rich text document, you may want to save it for later use. To support this, the RichTextBox class provides a method named named SaveFile that is overloaded with three versions. One of the versions uses the following syntax:
public void SaveFile(string path);
This method takes as argument the name or path to a file. It will save the file as RTF. If you want the user to save a file that is either RTF, ASCII, or another format, to specify the desired format, you can use the following version of the method:
public void SaveFile(string path, RichTextBoxStreamType fileType);
As seen in the first version, the first argument is the name or path of the file. The second argument allows you to specify the type of file that is being saved, which could be a normal ASCII text. This argument is of type RichTextBoxStreamType, which is an enumeration. The members of the RichTextBoxStreamType enumeration are PlainText, RichNoOleObjs, RichText, TextTextOleObjs, or TextTextOleObjs.
Instead of directly using the name of the file, you can create it as a stream. In this case, the RichTextBox class provides the following version of the SaveFile() method:
public void SaveFile(Stream data, RichTextBoxStreamType fileType);
This version expects a Stream-based object such as a FileStream variable.
Opening a Rich Text File
To assist you with opening a rich text file, the RichTextBox class is equipped with the LoadFile() method overloaded with three versions. The simplest versions has the following syntax:
public void LoadFile(string path);
This method takes as argument the name or path to a file. The file must be in RTF format. If it is not, the file will not be opened and the compiler would throw an IOException exception. If you want to give the user the ability to open different types of files, you should use the following version of the LoadFile() method:
public void LoadFile(string path, RichTextBoxStreamType fileType);
The first argument is the same as a the single argument of the first version. The second argument allows you to specify the type of file that is being opened, which could be a normal ASCII text. This argument is of type RichTextBoxStreamType.
Instead of directly using the name of the file, you can create it as a stream. In this case, the RichTextBox class provides the following version of the LoadFile() method:
public void LoadFile(Stream data, RichTextBoxStreamType fileType);
This version expects a Stream-based object such as a FileStream variable.
Practical Learning: Opening a Rich Text File
private void mnuFileNew_Click(object sender, EventArgs e)
{
// This is the question the user will have to answer
DialogResult answer = MessageBox.Show(
"The document has changed. Do you want to save it?" +
"\nClick\n" +
"Yes:\tTo save the document and create a new one.\n" +
"No:\tNot to save the document but create a new one.\n" +
"Cancel:\tNot to do anything",
"Editor - Saving a File",
MessageBoxButtons.YesNoCancel,
MessageBoxIcon.Question);
// When the user clicks File -> New to start a new document,
// before creating a new document,
// find out if the document is "dirty" ask the user whether to save or not
if (rchEditor.Modified == true)
{
// Present the message box to the user who
// will decide whether to save
if (answer == DialogResult.Yes)
{
// If the user answers Yes
// Find out if the current document has never been saved
if (CurrentFileName == "<Not Allowed>")
{
// If it has never been saved, then display the Save dialog box
if (dlgSave.ShowDialog() == DialogResult.OK)
{
// Save the file
rchEditor.SaveFile(dlgSave.FileName);
// Change the current file name to something not allowed
CurrentFileName = "<Not Allowed>";
// Display Untitled name of the current file on the title bar
Text = "Parasol - Untitled";
// Since the document has been saved and the user wants
// to create a new one, empty the control
rchEditor.Clear();
// Update the Modified attribute
rchEditor.Modified = false;
}
else // the user had clicked Cancel, don't do anything
return;
}
else // If the document was saved before, then simply update it
{
rchEditor.SaveFile(CurrentFileName);
// Change the current file name to something not allowed
CurrentFileName = "<Not Allowed>";
// Display Untitled name of the current file on the title bar
Text = "Parasol - Untitled";
rchEditor.Clear();
// Update the Modified attribute
rchEditor.Modified = false;
}
}
else if (answer == DialogResult.No)
{
// If the user answered No,
// then simply start a new document
rchEditor.Clear();
// Change the current file name to something not allowed
CurrentFileName = "<Not Allowed>";
// Display Untitled name of the current file on the title bar
Text = "Parasol - Untitled";
// Update the Modified attribute
rchEditor.Modified = false;
}
else // If the user clicked Cancel, don't do anything
return;
}
else // If the document was not modified, then start a new one
{
// If the user answered No,
// then simply start a new document
rchEditor.Clear();
// Change the current file name to something not allowed
CurrentFileName = "<Not Allowed>";
// Display Untitled name of the current file on the title bar
Text = "Parasol - Untitled";
// Update the Modified attribute
rchEditor.Modified = false;
}
}
private void mnuFileOpen_Click(object sender, EventArgs e)
{
// Find out if there was a document and if the document was "dirty"
if(rchEditor.Modified == true)
{
// Here is the question the user will answer
DialogResult answer = MessageBox.Show(
"The document has changed. Do you want to save it?" +
"\nClick\n" +
"Yes:\tTo save the document and open a new one.\n" +
"No:\tNot to save the document but open a new one.\n" +
"Cancel:\tNot to do anything",
"Editor - Opening a File",
MessageBoxButtons.YesNoCancel,
MessageBoxIcon.Question);
// Find out if the user wants to save the current document
if (answer == DialogResult.Yes)
{
// Find out if this is a new document
if (CurrentFileName == "<Not Allowed>")
{
// Since the user wants to save the document, display the Save dialog box
if (dlgSave.ShowDialog() == DialogResult.OK)
{
// Save the file
rchEditor.SaveFile(dlgSave.FileName);
}
else
return;
}
else
{
// This was not a new document,
// so, simply save it
rchEditor.SaveFile(CurrentFileName);
}
}
else if (answer == DialogResult.No)
{
// If the user answered No to the question, don't save
// Simply open the file
if (dlgOpen.ShowDialog() == DialogResult.OK)
{
// Open the new document after letting the user select it
rchEditor.LoadFile(dlgOpen.FileName);
// Change the file name of our archives
CurrentFileName = dlgOpen.FileName;
// Get the name of the file that the user selected
FileInfo fleParasol = new FileInfo(dlgOpen.FileName);
Text = "Parasol - " + fleParasol.Name;
rchEditor.Modified = false;
}
else
return;
}
else
return;
}
else
{
if (dlgOpen.ShowDialog() == DialogResult.OK)
{
// Open the new document after letting the user select it
rchEditor.LoadFile(dlgOpen.FileName);
// Change the file name of our archives
CurrentFileName = dlgOpen.FileName;
// Get the name of the file that the user selected
FileInfo fleParasol = new FileInfo(dlgOpen.FileName);
Text = "Parasol - " + fleParasol.Name;
rchEditor.Modified = false;
}
}
}
private void mnuFileSave_Click(object sender, EventArgs e)
{
// Find out if the current document has never been saved
// but is not empty
if( (rchEditor.Modified == true) &&
(CurrentFileName == "<Not Allowed>") )
{
// Since the document is dirty, display the Save As dialog box
if (dlgSave.ShowDialog() == DialogResult.OK)
{
// Retrieve the new name file and display
// the file in the rich edit control
rchEditor.SaveFile(dlgSave.FileName);
// Change/Update the global and complete name of the file,
// including its path
CurrentFileName = dlgSave.FileName;
// Extract the name of the file
FileInfo fleParasol = new FileInfo(dlgSave.FileName);
// Display the name of the current file on the title bar
Text = "Parasol - " + fleParasol.Name;
}
else
return;
}
else
{
// It appears that this document already had a name
// but the document was previously modified
// Therefore, simply save it internally
rchEditor.SaveFile(CurrentFileName);
}
}
private void mnuFileSaveAs_Click(object sender, EventArgs e)
{
if (dlgSave.ShowDialog() == DialogResult.OK)
{
rchEditor.SaveFile(dlgSave.FileName);
// Change the file name of our archives
CurrentFileName = dlgSave.FileName;
// Get the name of the file that the user selected
FileInfo fleParasol = new FileInfo(dlgSave.FileName);
Text = "Parasol - " + fleParasol.Name;
rchEditor.Modified = false;
}
}
private void mnuFileExit_Click(object sender, EventArgs e)
{
// Is the document dirty?
if (rchEditor.Modified == true)
{
// Since the document is dirty, find out if the user wants to save it
DialogResult answer = MessageBox.Show(
"The document has changed. Do you want to save it?" +
"\nClick\n" +
"Yes:\tTo save the document and close the application.\n" +
"No:\tNot to save the document but close the application.\n" +
"Cancel:\tNot to do anything",
"Parasol - Saving a File",
MessageBoxButtons.YesNoCancel, MessageBoxIcon.Question);
// If the user wants to save it
if (answer == DialogResult.Yes)
{
// Behave as if the user had clicked File . Save
mnuFileSave_Click(sender, e);
Close();
}
else if (answer == DialogResult.No)
{
// If the user doesn't want to save the document
Close();
}
// The user cancelled the action: do nothing
else
return;
}
else // There is no action to take
Close();
}
Rich Text Formatting
Formatting Text
We saw that you could change the general font of a text box and you can change the color of the characters. If you do this on a text box, all of the characters are changed to the same font and the same color. One of the extended properties of a rich text box over a regular text box is the ability to change the font and/ the color of individual characters, words, or paragraphs and the change applies only to the desired characters.
Before changing a character or a word, you must first select it. To change the font of the text that is selected on the control, the selected text is identified with the SelectionFont property. To change the color of the text that is selected, the selected text is identified with the SelectionColor property.
To assist you with this, you can use the Font dialog box. After selecting the character or word, you can transfer their attributes to the Font dialog box before displaying it. After using the dialog box, if the user clicks OK, you can retrieve the font and color characteristics then apply them to the selected character or text.
Practical Learning: Formatting Text
and click the formprivate void mnuFormatFont_Click(object sender, EventArgs e)
{
// Get the characteristics of the selected text
// Apply them to the Font dialog box
dlgFont.Font = rchEditor.SelectionFont;
dlgFont.Color = rchEditor.SelectionColor;
if (dlgFont.ShowDialog() == DialogResult.OK)
{
// Display the Font dialog box
// If the user clicks OK, get the characteristics of the font
// Apply them to the selected text of the Rich Edit control
rchEditor.SelectionFont = dlgFont.Font;
rchEditor.SelectionColor = dlgFont.Color;
}
}
The Paragraph Alignment
For a text-based control, a paragraph is a series of words that start with a letter or empty space until the flow of text is interrupted, which is usually made with a carriage return, or the end of the document. By itself, the paragraph controls its alignment and such details as Tab measurements or indentation. To set or change the properties of a paragraph, you must first select it. To select a paragraph, you don't need to formally select it or any portion of its text. As long as the cursor is positioned inside of the paragraph, any paragraph attribute you set or change would apply to the whole paragraph. To manipulate more than one paragraph at the same time, you or your user must select them. The paragraphs do not need to be wholly selected. As long as a section is selected on it, a paragraph is considered selected.
The most common property of a paragraph is its alignment, which states whether the paragraph is positioned to the left, the center, or the right. This characteristic is controlled by the SelectionAlignment property. The SelectionAlignment property is based on the HorizontalAlignment enumeration whose members are Left, Center, and Right. Because this property is applied on (individual) paragraphs, it is not available at design time.
To change the alignment at run time, assign the desired value to the SelectionAlignment property. In the following example, the alignment of the selected paragraph is set in response to the user clicking a button:
private void button1_Click(object sender, EventArgs e)
{
richTextBox1.SelectionAlignment = HorizontalAlignment.Center;
}
Practical Learning: Aligning a Paragraph
private void mnuFormatAlignLeft_Click(object sender, EventArgs e)
{
rchEditor.SelectionAlignment = HorizontalAlignment.Left;
}
private void mnuFormatAlignCenter_Click(object sender, EventArgs e)
{
rchEditor.SelectionAlignment = HorizontalAlignment.Center;
}
private void mnuFormatAlignRight_Click(object sender, EventArgs e)
{
rchEditor.SelectionAlignment = HorizontalAlignment.Right;
}
The Indentation of a Paragraph
Indentation is the number of empty characters that separate a paragraph edge from one of the borders of the rich text control. Indentation refers to the left side or the right side of a paragraph. Based on this, left indentation refers to the number of empty characters from the left border of the rich text control to the left edge of a paragraph. The rich text control provides indentation through various properties.
To support indentation from the left side of a paragraph, the RichTextBox class is equipped with a property named SelectionIndent property. To indent from the right side, the RichTextBox is equipped with the SelectionRightIndent property.
Practical Learning: Indenting a Paragraph
private void mnuFormatLeftIndent_Click(object sender, EventArgs e)
{
rchEditor.SelectionIndent += 10;
}
private void mnuFormatRightIndent_Click(object sender, EventArgs e)
{
rchEditor.SelectionRightIndent += 10;
}
A Bulleted Paragraph
Instead of just a regular section made only of text, you can create an unordered list of lines or paragraphs in your document. To support this, the RichTextBox class is equipped with a Boolean property named SelectionBullet. If you set this property to false on a paragraph, the paragraph would start with a bullet. If you apply this property to more than one consecutive paragraph, each would start with a bullet.
Practical Learning: Using a Rich Text Control
private void mnuFormatBulletList_Click(object sender, EventArgs e)
{
rchEditor.SelectionBullet = true;
}
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