spark/utils/FTETextUtil.as

////////////////////////////////////////////////////////////////////////////////
//
//  ADOBE SYSTEMS INCORPORATED
//  Copyright 2008 Adobe Systems Incorporated
//  All Rights Reserved.
//
//  NOTICE: Adobe permits you to use, modify, and distribute this file
//  in accordance with the terms of the license agreement accompanying it.
//
////////////////////////////////////////////////////////////////////////////////

package spark.utils
{

import flash.text.TextFormat;
import flash.text.engine.ElementFormat;
import flash.text.engine.FontDescription;
import flash.text.engine.FontLookup;
import flash.text.engine.TextBlock;
import flash.text.engine.TextElement;
import flash.text.engine.TextLine;

import flashx.textLayout.compose.ISWFContext;

import mx.core.IEmbeddedFontRegistry;
import mx.core.IFlexModuleFactory;
import mx.core.IUIComponent;
import mx.core.Singleton;
import mx.managers.ISystemManager;
import mx.styles.IStyleClient;

[ExcludeClass]

/**
 *  @private
 */
public class FTETextUtil
{
    include "../core/Version.as";

    //--------------------------------------------------------------------------
    //
    //  Methods - Font Baseline
    //
    //--------------------------------------------------------------------------

    //--------------------------------------------------------------------------
    //
    //  Class properties
    //
    //--------------------------------------------------------------------------

    /**
     *  @private
     *  Used in getEmbeddedFontContext().
     */
    private static var staticTextFormat:TextFormat;

    //----------------------------------
    //  embeddedFontRegistry
    //----------------------------------

    private static var noEmbeddedFonts:Boolean;

    /**
     *  @private
     *  Storage for the _embeddedFontRegistry property.
     *  Note: This gets initialized on first access,
     *  not when this class is initialized, in order to ensure
     *  that the Singleton registry has already been initialized.
     */
    private static var _embeddedFontRegistry:IEmbeddedFontRegistry;

    /**
     *  @private
     *  A reference to the embedded font registry.
     *  Single registry in the system.
     *  Used to look up the moduleFactory of a font.
     */
    private static function get embeddedFontRegistry():IEmbeddedFontRegistry
    {
        if (!_embeddedFontRegistry && !noEmbeddedFonts)
        {
            try
            {
                _embeddedFontRegistry = IEmbeddedFontRegistry(
                    Singleton.getInstance("mx.core::IEmbeddedFontRegistry"));
            }
            catch (e:Error)
            {
                noEmbeddedFonts = true;
            }
        }

        return _embeddedFontRegistry;
    }

    //--------------------------------------------------------------------------
    //
    //  Class methods
    //
    //--------------------------------------------------------------------------

    /**
     *  Method to measure baseline position
     *
     *  @param client The IStyleClient to use to calculate the baseline.
     *  @param height Height of client.  Used only for degenerate cases.
     *  @param moduleFactory The default moduleFactory to use for the font.
     */
    public static function calculateFontBaseline(client:IStyleClient, height:Number, moduleFactory:IFlexModuleFactory):Number
    {
        var fontDescription:FontDescription = new FontDescription();
        var embeddedFontContext:IFlexModuleFactory;

        var s:String;

        s = client.getStyle("cffHinting");
        if (s != null)
            fontDescription.cffHinting = s;

        s = client.getStyle("fontFamily");
        if (s != null)
            fontDescription.fontName = s;

        s = client.getStyle("fontLookup");
        if (s != null)
        {
            // FTE understands only "device" and "embeddedCFF"
            // for fontLookup. But Flex allows this style to be
            // set to "auto", in which case we automatically
            // determine it based on whether the CSS styles
            // specify an embedded font.
            if (s == "auto")
            {
                embeddedFontContext = getEmbeddedFontContext(client, moduleFactory);
                s = (embeddedFontContext) ?
                    FontLookup.EMBEDDED_CFF :
                    FontLookup.DEVICE;
            }
            fontDescription.fontLookup = s;
        }

        s = client.getStyle("fontStyle");
        if (s != null)
            fontDescription.fontPosture = s;

        s = client.getStyle("fontWeight");
        if (s != null)
            fontDescription.fontWeight = s;

        var elementFormat:ElementFormat = new ElementFormat();
        elementFormat.fontDescription = fontDescription;
        elementFormat.fontSize = client.getStyle("fontSize");

        var textElement:TextElement = new TextElement();
        textElement.elementFormat = elementFormat;
        textElement.text = "Wj";

        var textBlock:TextBlock = new TextBlock();
        textBlock.content = textElement;

        var textLine:TextLine;
        if (embeddedFontContext)
        {
            var swfContext:ISWFContext = ISWFContext(embeddedFontContext);
            textLine = swfContext.callInContext(
						textBlock.createTextLine, textBlock,
						[ null, 1000]);
        }
        else
            textLine = textBlock.createTextLine(null, 1000);

        if (height < 2 + textLine.ascent + 2)
            return int(height + (textLine.ascent - height) / 2);

        return 2 + textLine.ascent;
    }

	/**
	 *  @private
	 *  Uses the component's CSS styles to determine the module factory
	 *  that should creates its TextLines.
	 */
    private static function getEmbeddedFontContext(client:IStyleClient, moduleFactory:IFlexModuleFactory):IFlexModuleFactory
	{
		var fontContext:IFlexModuleFactory;

		var fontLookup:String = client.getStyle("fontLookup");
		if (fontLookup != FontLookup.DEVICE)
        {
			var font:String = client.getStyle("fontFamily");
			var bold:Boolean = client.getStyle("fontWeight") == "bold";
			var italic:Boolean = client.getStyle("fontStyle") == "italic";

            var localLookup:ISystemManager;
            if (moduleFactory != null && moduleFactory is ISystemManager)
                localLookup = ISystemManager(moduleFactory);
            else if (client is IUIComponent)
            {
                var uic:IUIComponent = IUIComponent(client);
                if (uic.parent is IUIComponent)
                    localLookup = IUIComponent(uic.parent).systemManager;
            }

            fontContext = embeddedFontRegistry.getAssociatedModuleFactory(
            	font, bold, italic, client, moduleFactory, localLookup, true);
        }

        if (!fontContext && fontLookup == FontLookup.EMBEDDED_CFF)
        {
            // if we couldn't find the font and somebody insists it is
            // embedded, try the default fontContext
            fontContext = moduleFactory;
        }

        return fontContext;
	}

}

}