gecko-dev/image/test/unit/test_encoder_png.js

/*
 * Test for PNG encoding in ImageLib
 *
 */

const Ci = Components.interfaces;
const Cc = Components.classes;

var png1A = {
        // A 3x3 image, rows are red, green, blue.
        // RGB format, transparency defaults.

        transparency : null,

        frames  : [
                {
                        width  : 3,    height : 3,

                        format : Ci.imgIEncoder.INPUT_FORMAT_RGB, stride : 9,

                        pixels : [
                                255,0,0,  255,0,0, 255,0,0,
                                0,255,0,  0,255,0, 0,255,0,
                                0,0,255,  0,0,255, 0,0,255,
                                ]
                }

                ],
        expected : "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAMAAAADCAIAAADZSiLoAAAAEUlEQVQImWP4z8AAQTAamQkAhpcI+DeMzFcAAAAASUVORK5CYII="
};

var png1B = {
        // A 3x3 image, rows are red, green, blue.
        // RGB format, transparency=none.

        transparency : "none",

        frames  : [
                {
                        width  : 3,    height : 3,

                        format : Ci.imgIEncoder.INPUT_FORMAT_RGB, stride : 9,

                        pixels : [
                                255,0,0,  255,0,0, 255,0,0,
                                0,255,0,  0,255,0, 0,255,0,
                                0,0,255,  0,0,255, 0,0,255,
                                ]
                }

                ],
        expected : "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAMAAAADCAIAAADZSiLoAAAAEUlEQVQImWP4z8AAQTAamQkAhpcI+DeMzFcAAAAASUVORK5CYII="
};

var png2A = {
        // A 3x3 image, rows are: red, green, blue. Columns are: 0%, 33%, 66% transparent.

        transparency : null,

        frames  : [
                {
                        width  : 3,    height : 3,

                        format : Ci.imgIEncoder.INPUT_FORMAT_RGBA, stride : 12,

                        pixels : [
                                255,0,0,255,  255,0,0,170, 255,0,0,85,
                                0,255,0,255,  0,255,0,170, 0,255,0,85,
                                0,0,255,255,  0,0,255,170, 0,0,255,85
                                ]
                }

                ],
        expected : "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAMAAAADCAYAAABWKLW/AAAAIElEQVQImSXJMQEAMAwEIUy+yZi8DmVFFBcjycn86GgPJw4O8v9DkkEAAAAASUVORK5CYII="
};

var png2B = {
        // A 3x3 image, rows are: red, green, blue. Columns are: 0%, 33%, 66% transparent,
        // but transparency will be ignored.

        transparency : "none",

        frames  : [
                {
                        width  : 3,    height : 3,

                        format : Ci.imgIEncoder.INPUT_FORMAT_RGBA, stride : 12,

                        pixels : [
                                255,0,0,255,  255,0,0,170, 255,0,0,85,
                                0,255,0,255,  0,255,0,170, 0,255,0,85,
                                0,0,255,255,  0,0,255,170, 0,0,255,85
                                ]
                }

                ],
        expected : "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAMAAAADCAIAAADZSiLoAAAAEUlEQVQImWP4z8AAQTAamQkAhpcI+DeMzFcAAAAASUVORK5CYII="
};

// Main test entry point.
function run_test() {
        dump("Checking png1A...\n")
        run_test_for(png1A);
        dump("Checking png1B...\n")
        run_test_for(png1B);
        dump("Checking png2A...\n")
        run_test_for(png2A);
        dump("Checking png2B...\n")
        run_test_for(png2B);
}; 


function run_test_for(input) {
        var encoder, dataURL;

        encoder = encodeImage(input);
        dataURL = makeDataURL(encoder, "image/png");
        do_check_eq(dataURL, input.expected);

        encoder = encodeImageAsync(input);
        dataURL = makeDataURLFromAsync(encoder, "image/png", input.expected);
};


function encodeImage(input) {
        var encoder = Cc["@mozilla.org/image/encoder;2?type=image/png"].createInstance();
        encoder.QueryInterface(Ci.imgIEncoder);

        var options = "";
        if (input.transparency) {
                options += "transparency=" + input.transparency;
        }

        var frame = input.frames[0];
        encoder.initFromData(frame.pixels, frame.pixels.length,
                                frame.width, frame.height, frame.stride,
                                frame.format, options);
        return encoder;
}

function _encodeImageAsyncFactory(frame, options, encoder)
{
        function finishEncode() {
            encoder.addImageFrame(frame.pixels, frame.pixels.length,
                                  frame.width, frame.height, frame.stride,
                                  frame.format, options);
            encoder.endImageEncode();
        }
        return finishEncode;
}

function encodeImageAsync(input)
{
        var encoder = Cc["@mozilla.org/image/encoder;2?type=image/png"].createInstance();
        encoder.QueryInterface(Ci.imgIEncoder);

        var options = "";
        if (input.transparency) {
                options += "transparency=" + input.transparency;
        }

        var frame = input.frames[0];
        encoder.startImageEncode(frame.width, frame.height,
                                 frame.format, options);

        do_timeout(50, _encodeImageAsyncFactory(frame, options, encoder));
        return encoder;
}


function makeDataURL(encoder, mimetype) {
        var rawStream = encoder.QueryInterface(Ci.nsIInputStream);

        var stream = Cc["@mozilla.org/binaryinputstream;1"].createInstance();
        stream.QueryInterface(Ci.nsIBinaryInputStream);

        stream.setInputStream(rawStream);

        var bytes = stream.readByteArray(stream.available()); // returns int[]

        var base64String = toBase64(bytes);

        return "data:" + mimetype + ";base64," + base64String;
}

function makeDataURLFromAsync(encoder, mimetype, expected) {
        do_test_pending();
        var rawStream = encoder.QueryInterface(Ci.nsIAsyncInputStream);

        var currentThread = Cc["@mozilla.org/thread-manager;1"].getService().currentThread;

        var bytes = [];

        var binarystream = Cc["@mozilla.org/binaryinputstream;1"].createInstance();
        binarystream.QueryInterface(Ci.nsIBinaryInputStream);

        var asyncReader =
        {
            onInputStreamReady: function(stream)
            {
                binarystream.setInputStream(stream);
                var available = 0;
                try {
                  available = stream.available();
                } catch(e) { }

                if (available > 0)
                {
                    bytes = bytes.concat(binarystream.readByteArray(available));
                    stream.asyncWait(this, 0, 0, currentThread);
                } else {
                    var base64String = toBase64(bytes);
                    var dataURL = "data:" + mimetype + ";base64," + base64String;
                    do_check_eq(dataURL, expected);
                    do_test_finished();
                }

            }
        };
        rawStream.asyncWait(asyncReader, 0, 0, currentThread);
}

/* toBase64 copied from extensions/xml-rpc/src/nsXmlRpcClient.js */

/* Convert data (an array of integers) to a Base64 string. */
const toBase64Table = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz' +
    '0123456789+/';
const base64Pad = '=';
function toBase64(data) {
    var result = '';
    var length = data.length;
    var i;
    // Convert every three bytes to 4 ascii characters.
    for (i = 0; i < (length - 2); i += 3) {
        result += toBase64Table[data[i] >> 2];
        result += toBase64Table[((data[i] & 0x03) << 4) + (data[i+1] >> 4)];
        result += toBase64Table[((data[i+1] & 0x0f) << 2) + (data[i+2] >> 6)];
        result += toBase64Table[data[i+2] & 0x3f];
    }

    // Convert the remaining 1 or 2 bytes, pad out to 4 characters.
    if (length%3) {
        i = length - (length%3);
        result += toBase64Table[data[i] >> 2];
        if ((length%3) == 2) {
            result += toBase64Table[((data[i] & 0x03) << 4) + (data[i+1] >> 4)];
            result += toBase64Table[(data[i+1] & 0x0f) << 2];
            result += base64Pad;
        } else {
            result += toBase64Table[(data[i] & 0x03) << 4];
            result += base64Pad + base64Pad;
        }
    }

    return result;
}