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Bug #547

Suggested modification to rfonts.js to overcome the 'cannot_load_font' issue

Added by Phil Bell almost 3 years ago.

Status:
New
Priority:
Normal
Assignee:
-
Target version:
-
Start date:
10/13/2020
Due date:
% Done:

0%

Estimated time:
Affected version:

Description

Through lots of testing on mobile it is often that the Fonts.prototype.loadFont function will fail to load a font in the limited 3000ms timeout, this is not really a problem as the font will eventually be loaded by the browser and be available to AOZ.

This behaviour explains why we have seen the alert popup on first load but then a refresh will successfully load the application.

Currently, if the timeout occurs the Fonts.prototype.loadFont function will set the 'cannot_load_font' error, the user will see a browser alert with this error message and be left with an unresponsive "blank" screen.

I suggest the Fonts.prototype.loadFont should be modified to ignore the timeout error and allow the app to continue.

Below if the modified function, I have tested on mobile and using the network limiter in the Chrome Dev Tools

Fonts.prototype.loadFont = function( fontInformation, weight, italic, stretch, callback, extra )
{
weight = typeof weight == 'undefined' ? 'normal' : weight;
italic = typeof italic == 'undefined' ? 'normal' : italic;
stretch = typeof stretch == 'undefined' ? 'normal' : stretch;

var self = this;
if ( fontInformation.type == 'google' )
{
    var fontStyleIndex = 'italic:' + italic + 'weight:' + weight + 'stretch:' + stretch;
    if ( !fontInformation.fonts[ fontStyleIndex ] )
    {
        var font =
        {
            weight: weight,
            style: italic,
            strech: stretch
        };
        var observer = new FontFaceObserver( fontInformation.name, font );
        this.aoz.loadingMax++;
        observer.load().then( function()
        {
            self.aoz.loadingCount++;
            font.fontInformation = fontInformation;
            font.baseLines = [];
            fontInformation.fonts[ fontStyleIndex ] = font;
            callback( true, font, extra );
        }, function(e)
        {
            // Phil Bell 13/10/2020
            // Dont error if timeout exceeded, maybe slow network connection, font will load eventually
            if (e.message.indexOf('timeout exceeded') > -1)
            {
                self.aoz.loadingCount++;
                font.fontInformation = fontInformation;
                font.baseLines = [];
                fontInformation.fonts[ fontStyleIndex ] = font;
                callback( true, font, extra );
            }
            else
            {
                self.aoz.loadingCount++;
                self.aoz.loadingError = 'cannot_load_font';
                callback( false, null, extra );
                callback( true, fontInformation.fonts[ fontStyleIndex ], extra );
            }
        } );
    }
    else
    {
        callback( true, fontInformation.fonts[ fontStyleIndex ], extra );
    }
}
else if ( fontInformation.type == 'amiga' )
{
    if ( !fontInformation.font )
    {
        var path = './resources/fonts/amiga/' + fontInformation.name + '.js';
        this.aoz.loadingMax++;
        this.utilities.loadScript( path, {}, function( response, data, extra )
        {
            self.aoz.loadingCount++;
            if ( response )
            {
                fontInformation.font =
                {
                    fontCode: AmigaFonts[ fontInformation.name ],
                    fontInformation: fontInformation,
                    canvasDefinitions: [],
                    baseLines: [],
                    italic: italic,
                    weight: weight,
                    stretch: stretch
                };
                callback( true, fontInformation.font, extra );
            }
            else
            {
                self.aoz.loadingError = 'cannot_load_font';
                callback( false, null, extra );
            }
        } );
    }
    else
    {
        callback( true, fontInformation.font, extra );
    }
}

};

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