Walkthrough: Updating the MFC Scribble Application (Part 2)

Artikkeli
08/03/2021

Part 1 of this walkthrough showed how to add an Office Fluent Ribbon to the classic Scribble application. This part shows how to add ribbon panels and controls that users can use instead of menus and commands.

Prerequisites

Visual C++ Samples

Sections

This part of the walkthrough has the following sections:

Adding New Panels to the Ribbon
Adding a Help Panel to the Ribbon
Adding a Pen Panel to the Ribbon
Adding a Color Button to the Ribbon
Adding a Color Member to the Document Class
Initializing Pens and Saving Preferences

Adding New Panels to the Ribbon

These steps show how to add a View panel that contains two check boxes that control the visibility of the toolbar and the status bar, and also a Window panel that contains a vertically oriented split button that controls the creation and arrangement of multiple-document interface (MDI) windows.

To add a View panel and Window panel to the ribbon bar

Create a panel named View, which has two check boxes that toggle the status bar and toolbar.
1. From the Toolbox, drag a Panel to the Home category. Then drag two Check Boxes to the panel.
2. Click the panel to modify its properties. Change Caption to View.
3. Click the first check box to modify its properties. Change ID to ID_VIEW_TOOLBAR and Caption to Toolbar.
4. Click the second check box to modify its properties. Change ID to ID_VIEW_STATUS_BAR and Caption to Status Bar.
Create a panel named Window that has a split button. When a user clicks the split button, a shortcut menu displays three commands that are already defined in the Scribble application.
1. From the Toolbox, drag a Panel to the Home category. Then drag a Button to the panel.
2. Click the panel to modify its properties. Change Caption to Window.
3. Click the button. Change Caption to Windows, Keys to w, Large Image Index to 1, and Split Mode to False. Then click the ellipsis (...) next to Menu Items to open the Items Editor dialog box.
4. Click Add three times to add three buttons.
5. Click the first button and then change Caption to New Window, and ID to ID_WINDOW_NEW.
6. Click the second button and then change Caption to Cascade, and ID to ID_WINDOW_CASCADE.
7. Click the third button and then change Caption to Tile, and ID to ID_WINDOW_TILE_HORZ.
Save the changes, and then build and run the application. The View and Window panels should be displayed. Click the buttons to confirm that they function correctly.

Adding a Help Panel to the Ribbon

Now, you can assign two menu items that are defined in the Scribble application to ribbon buttons that are named Help Topics and About Scribble. The buttons are added to a new panel named Help.

To add a Help panel

From the Toolbox, drag a Panel to the Home category. Then drag two Buttons to the panel.
Click the panel to modify its properties. Change Caption to Help.
Click the first button. Change Caption to Help Topics, and ID to ID_HELP_FINDER.
Click the second button. Change Caption to About Scribble..., and ID to ID_APP_ABOUT.
Save the changes, and then build and run the application. A Help panel that contains two ribbon buttons should be displayed.

Important

When you click the Help Topics button, the Scribble application opens a compressed HTML (.chm) help file named your_project_name.chm. Consequently, if your project is not named Scribble, you must rename the help file to your project name.

Adding a Pen Panel to the Ribbon

Now, add a panel to display buttons that control the thickness and the color of the pen. This panel contains a check box that toggles between thick and thin pens. Its functionality resembles that of the Thick Line menu item in the Scribble application.

The original Scribble application lets the user select pen widths from a dialog box that appears when the user clicks Pen Widths on the menu. Because the ribbon bar has ample room for new controls, you can replace the dialog box by using two combo boxes on the ribbon. One combo box adjusts the width of the thin pen and the other combo box adjusts the width of the thick pen.

To add a Pen panel and combo boxes to the ribbon

From the Toolbox, drag a Panel to the Home category. Then drag a Check Box and two Combo Boxes to the panel.
Click the panel to modify its properties. Change Caption to Pen.
Click the check box. Change Caption to Use Thick, and ID to ID_PEN_THICK_OR_THIN.
Click the first combo box. Change Caption to Thin Pen, ID to ID_PEN_THIN_WIDTH, Type to Drop List, Data to 1;2;3;4;5;6;7;8;9;, and Text to 2.
Click the second combo box. Change Caption to Thick Pen, ID to ID_PEN_THICK_WIDTH, Type to Drop List, Data to 5;6;7;8;9;10;11;12;13;14;15;16;17;18;19;20;, and Text to 5.
The new combo boxes don't correspond to any existing menu items, so you must create a menu item for every pen option.
1. In the Resource View window, open the IDR_SCRIBBTYPE menu resource.
2. Click Pen to open the pen menu. Then click Type Here and type Thi&n Pen.
3. Right-click the text that you typed to open the Properties window, and then change the ID property to ID_PEN_THIN_WIDTH.
4. Create an event handler for every pen menu item. Right-click the Thi&n Pen menu item that you created and then click Add Event Handler. The Event Handler Wizard is displayed.
5. In the Class list box in the wizard, select CScribbleDoc and then click Add and Edit. The command creates an event handler named CScribbleDoc::OnPenThinWidth.
6. Add the following code to CScribbleDoc::OnPenThinWidth.
```
// Get a pointer to the ribbon bar
CMFCRibbonBar* pRibbon = ((CMDIFrameWndEx*) AfxGetMainWnd())->GetRibbonBar();
ASSERT_VALID(pRibbon);

// Get a pointer to the Thin Width combo box
CMFCRibbonComboBox* pThinComboBox = DYNAMIC_DOWNCAST(
CMFCRibbonComboBox, pRibbon->FindByID(ID_PEN_THIN_WIDTH));

//Get the selected value
int nCurSel = pThinComboBox->GetCurSel();
if (nCurSel>= 0)
{
    m_nThinWidth = atoi(CStringA(pThinComboBox->GetItem(nCurSel)));
}

// Create a new pen using the selected width
ReplacePen();
```
Next, create a menu item and event handlers for the thick pen.
1. In the Resource View window, open the IDR_SCRIBBTYPE menu resource.
2. Click Pen to open the pen menu. Then click Type Here and type Thic&k Pen.
3. Right-click the text that you typed to display the Properties window. Change the ID property to ID_PEN_THICK_WIDTH.
4. Right-click the Thick Pen menu item that you created and then click Add Event Handler. The Event Handler Wizard is displayed.
5. In the Class list box of the wizard, select CScribbleDoc and then click Add and Edit. The command creates an event handler named CScribbleDoc::OnPenThickWidth.
6. Add the following code to CScribbleDoc::OnPenThickWidth.
```
// Get a pointer to the ribbon bar
CMFCRibbonBar* pRibbon = ((CMDIFrameWndEx *) AfxGetMainWnd())->GetRibbonBar();
ASSERT_VALID(pRibbon);

CMFCRibbonComboBox* pThickComboBox = DYNAMIC_DOWNCAST(
    CMFCRibbonComboBox, pRibbon->FindByID(ID_PEN_THICK_WIDTH));
// Get the selected value
int nCurSel = pThickComboBox->GetCurSel();
if (nCurSel>= 0)
{
    m_nThickWidth = atoi(CStringA(pThickComboBox->GetItem(nCurSel)));
}

// Create a new pen using the selected width
ReplacePen();
```
Save the changes, and then build and run the application. New buttons and combo boxes should be displayed. Try using different pen widths to scribble.

Adding a Color Button to the Pen Panel

Next, add a CMFCRibbonColorButton object that lets the user scribble in color.

To add a color button to the Pen panel

Before you add the color button, create a menu item for it. In the Resource View window, open the IDR_SCRIBBTYPE menu resource. Click the Pen menu item to open the pen menu. Then click Type Here and type &Color. Right-click the text that you typed to display the Properties window. Change the ID to ID_PEN_COLOR.
Now add the color button. From the Toolbox, drag a Color Button to the Pen panel.
Click the color button. Change Caption to Color, ID to ID_PEN_COLOR, Simple Look to True, Large Image Index to 1, and Split Mode to False.
Save the changes, and then build and run the application. The new color button should be displayed on the Pen panel. However, it can't be used because it doesn't yet have an event handler. The next steps show how to add an event handler for the color button.

Adding a Color Member to the Document Class

Because the original Scribble application doesn't have color pens, you must write an implementation for them. To store the pen color of the document, add a new member to the document class, CscribbleDoc.

To add a color member to the document class

In scribdoc.h, in the CScribbleDoc class, find the // Attributes section. Add the following lines of code after the definition of the m_nThickWidth data member.
```
// Current pen color
COLORREF m_penColor;
```
Every document contains a list of stokes that the user has already drawn. Every stroke is defined by a CStroke object. The CStroke class doesn't include information about pen color, so you must modify the class. In scribdoc.h, in the CStroke class, add the following lines of code after the definition of the m_nPenWidth data member.
```
// Pen color for the stroke
COLORREF m_penColor;
```
In scribdoc.h, add a new CStroke constructor whose parameters specify a width and color. Add the following line of code after the CStroke(UINT nPenWidth); statement.
```
CStroke(UINT nPenWidth, COLORREF penColor);
```

In scribdoc.cpp, add the implementation of the new CStroke constructor. Add the following code after the implementation of the CStroke::CStroke(UINT nPenWidth) constructor.

// Constructor that uses the document's current width and color
CStroke::CStroke(UINT nPenWidth, COLORREF penColor)
{
    m_nPenWidth = nPenWidth;
    m_penColor = penColor;
    m_rectBounding.SetRectEmpty();
}

Change the second line of the CStroke::DrawStroke method as follows.
```
if (!penStroke.CreatePen(PS_SOLID, m_nPenWidth, m_penColor))
```
Set the default pen color for the document class. In scribdoc.cpp, add the following lines to CScribbleDoc::InitDocument, after the m_nThickWidth = 5; statement.
```
// default pen color is black
m_penColor = RGB(0, 0, 0);
```
In scribdoc.cpp, change the first line of the CScribbleDoc::NewStroke method to the following.
```
CStroke* pStrokeItem = new CStroke(m_nPenWidth, m_penColor);
```
Change the last line of the CScribbleDoc::ReplacePen method to the following.
```
m_penCur.CreatePen(PS_SOLID, m_nPenWidth, m_penColor);
```
You added the m_penColor member in a previous step. Now, create an event handler for the color button that sets the member.
1. In the Resource View window, open the IDR_SCRIBBTYPE menu resource.
2. Right-click the Color menu item and click Add Event Handler. The Event Handler Wizard appears.
3. In the Class list box in the wizard, select CScribbleDoc and then click the Add and Edit button. The command creates the CScribbleDoc::OnPenColor event handler stub.

Replace the stub for the CScribbleDoc::OnPenColor event handler with the following code.

void CScribbleDoc::OnPenColor()
{
    // Change pen color to reflect color button's current selection
    CMFCRibbonBar* pRibbon = ((CMDIFrameWndEx*) AfxGetMainWnd())->GetRibbonBar();
    ASSERT_VALID(pRibbon);

    CMFCRibbonColorButton* pColorBtn = DYNAMIC_DOWNCAST(
        CMFCRibbonColorButton, pRibbon->FindByID(ID_PEN_COLOR));

    m_penColor = pColorBtn->GetColor();
    // Create new pen using the selected color
    ReplacePen();
}

Save the changes and then build and run the application. You can now press the color button and change the pen's color.

Initializing Pens and Saving Preferences

Next, initialize the color and width of the pens. Finally, save and load a color drawing from a file.

To initialize controls on the ribbon bar

Initialize the pens on the ribbon bar.

Add the following code to scribdoc.cpp, in the CScribbleDoc::InitDocument method, after the m_sizeDoc = CSize(200,200) statement.

// Reset the ribbon UI to its initial values
CMFCRibbonBar* pRibbon =
    ((CMDIFrameWndEx*) AfxGetMainWnd())->GetRibbonBar();
ASSERT_VALID(pRibbon);

CMFCRibbonColorButton* pColorBtn = DYNAMIC_DOWNCAST(
    CMFCRibbonColorButton,
    pRibbon->FindByID(ID_PEN_COLOR));

// Set ColorButton to black
pColorBtn->SetColor(RGB(0, 0, 0));

CMFCRibbonComboBox* pThinComboBox = DYNAMIC_DOWNCAST(
    CMFCRibbonComboBox,
    pRibbon->FindByID(ID_PEN_THIN_WIDTH));

// Set Thin pen combobox to 2
pThinComboBox->SelectItem(1);

CMFCRibbonComboBox* pThickComboBox = DYNAMIC_DOWNCAST(
    CMFCRibbonComboBox,
    pRibbon->FindByID(ID_PEN_THICK_WIDTH));

// Set Thick pen combobox to 5
pThickComboBox->SelectItem(0);

Save a color drawing to a file. Add the following statement to scribdoc.cpp, in the CStroke::Serialize method, after the ar << (WORD)m_nPenWidth; statement.
```
ar << (COLORREF)m_penColor;
```
Finally, load a color drawing from a file. Add the following line of code, in the CStroke::Serialize method, after the m_nPenWidth = w; statement.
```
ar >> m_penColor;
```
Now scribble in color and save your drawing to a file.

Conclusion

You've updated the MFC Scribble application. Use this walkthrough as a guide when you modify your existing applications.

Jaa