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Setting Font Size and Style

You can set font size and style for the current selection by calling the TXNSetTypeAttributes function. The current selection can be a range of text selected by the user or specified by your application. You specify the current selection with the iStartOffset and iEndOffset parameters of the TXNSetTypeAttributes function.

MLTE stores font attributes in a TXNTypeAttributes structure. This structure contains the TXNAttributeData union, and it is that union you use to pass attribute values. The tag field of the TXNTypeAttributes structure defines the type of data in the TXNAttributeData union, and the size field of the TXNTypeAttributes structure defines the size of the data in the TXNAttributeData union.

Typically your application would have a function that handles menu item selections. If a user makes a selection from the Size or Style menu, you change the appropriate values in the TXNTypeAttributes structure, then you call the TXNSetTypeAttributes function to change the attributes for the current selection.

The code fragment in Listing 3-9 shows how your application can handle size and style changes within a function that handles menu item selections.

Listing 3-9	Handling changes made in the Size and Style menus
        TXNObject        textObject;
        TXNTypeAttributes typeAttr;

        case mSize:
            {
                static short aFontSizeList[] = {9, 10, 12, 14, 18, 24, 36};
                short shortValue = aFontSizeList[menuItem - 1];
                //  Assign the size attributes.
                typeAttr.tag = kTXNQDFontSizeAttribute;
                typeAttr.size = kTXNFontSizeAttributeSize;
                typeAttr.data.dataValue = shortValue << 16;
                //  Use the MLTE function to set the size attributes.
                 status = TXNSetTypeAttributes (textObject, 1, &typeAttr, 
                            kTXNUseCurrentSelection,
                            kTXNUseCurrentSelection);
                // If there is an error
                 if (status != noErr)       
                    // call your own error handling function.
                    MyAlertUser (eNoFontSize);
                break; 
        case mStyle:
            {
                Style   newStyle;
                // Assign the new style based on the menu item
                // the user chooses.
                switch (menuItem) 
                {
                    case iPlain:
                        newStyle = normal;              
                        break;
                    case iBold:
                        newStyle = bold;                    
                        break;
                    case iItalic:
                        newStyle = italic;          
                        break;
                    case iUnderline:
                        newStyle = underline;   
                        break;
                    case iOutline:
                        newStyle = outline;         
                        break;
                    case iShadow:
                        newStyle = shadow;                  
                        break;
                    case iCondensed:
                        newStyle = condense;    
                        break;      
                    case iExtended:
                        newStyle = extend;      
                        break;
                    default:
                        break;
                }
                // Assign the style attributes.
                typeAttr.tag = kTXNQDFontStyleAttribute;
                typeAttr.size = kTXNQDFontStyleAttributeSize;
                typeAttr.data.dataValue = newStyle;
                // Use the MLTE function to set the style attributes.
                status = TXNSetTypeAttributes(textObject, 1, &typeAttr,
                            kTXNUseCurrentSelection,
                            kTXNUseCurrentSelection);
                // If there is an error
                if (status != noErr)        
                    // call your own error handling function.
                    MyAlertUser (eNoFontStyle);
                break;