Laden von Freihanddaten (HTML)

Applies to Windows only

In diesem Thema wird beschrieben, wie Freihanddaten geladen werden, indem sie aus ISF-Metadaten, die in einer GIF-Datei (Graphics Interchange Format) eingebettet sind, deserialisiert werden.

Durch Einbetten von Freihanddaten in Form von ISF-Metadaten in eine GIF-Datei ist es möglich, Freihandeingaben in Anwendungen anzuzeigen, die nicht über die Funktion zur Freihandeingabe verfügen, während die Funktionen für Anwendungen mit Freihandeingabe in vollem Umfang erhalten bleiben. Dieser Vorgang eignet sich besonders gut, um Freihandinhalt innerhalb einer HTML-Datei zu übertragen und ihn sowohl für Freihandanwendungen als auch Anwendungen ohne Freihandfunktion verfügbar zu machen.

Hinweis  

Bei ISF handelt es sich um die kompakteste permanente Freihanddarstellung. Sie kann in ein binäres Dokumentformat eingebettet oder direkt in die Zwischenablage kopiert werden, wobei verschiedenste Freihandeigenschaften wie Druck, Breite, Farbe, Neigung, Drehung usw. erhalten bleiben.

Updates für Windows 8.1:  Windows 8.1 führt eine Reihe von Updates und Verbesserungen an den Zeigereingabe-APIs ein. Weitere Informationen finden Sie in API-Änderungen für Windows 8.1.

Wissenswertes

Technologien

Voraussetzungen

In diesem Thema wird davon ausgegangen, dass Sie mit JavaScript eine einfache Windows Store-App erstellen können, für die die Vorlage "Windows-Bibliothek für JavaScript" verwendet wird.

Anweisungen

Schritt 1:

Die loadStrokes-Funktion in diesem Beispiel zeigt, wie es gemacht wird:

  • Zeigen Sie einen Bildschirm zum Öffnen einer Datei an, in der der Dateityp mithilfe des FileOpenPicker-Objekts auf das GIF-Format beschränkt wird.
  • Richten Sie über die OpenAsync-Methode einen Eingabedatenstrom ein.
  • Verwenden Sie die LoadAsync-Methode eines InkManager-Objekts (inkManager) zum Entserialisieren der Freihanddaten aus einer GIF-Datei (storageFile).

// Load strokes into an inkManager.
function loadStrokes()
{
    // Set up the file open screen.
    var openPicker = Windows.Storage.Pickers.FileOpenPicker();
    openPicker.suggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.picturesLibrary;
    openPicker.fileTypeFilter.replaceAll([".gif"]);

    // Set up the stream.
    var loadStream = null;

    // Asynchronously load the ink data from the stream.
    openPicker.pickSingleFileAsync().done(
        function (file)
        {
            if (null != file)
            {
                file.openAsync(Windows.Storage.FileAccessMode.read).then(
                    function (stream) {
                        loadStream = stream;
                        return inkManager.loadAsync(loadStream);
                    }).done(
                        function()
                        {
                            var strokes = inkManager.getStrokes().length;
                            if (strokes === 0)
                            {
                                statusMessage.innerText = "No strokes in file.";
                            }
                            else
                            {
                                statusMessage.innerText = strokes + " strokes loaded.";
                            }
                            renderAllStrokes();
                            loadStream.close();
                        },
                        function (e)
                        {
                            statusMessage.innerText = "Load failed.";
                            if (loadStream)
                            {
                                // Close the stream if open.
                                loadStream.close();
                            }
                        });
            }
        });
}


Anmerkungen

GIF ist das einzige unterstütze Format zum Speichern von Freihanddaten in Windows 8 (siehe So wird's gemacht: Speichern von Freihanddaten).

Aus Gründen der Rückwärtskompatibilität werden allerdings von der LoadAsync-Methode die folgenden Formate unterstützt.

FormatBeschreibung
InkSerializedFormat Dieses Format definiert Freihandeingaben, die mithilfe von ISF (Ink Serialized Format) beibehalten werden. Dabei handelt es sich um die kompakteste permanente Freihanddarstellung. Sie kann in ein binäres Dokumentformat eingebettet oder direkt in der Zwischenablage platziert werden.
Base64InkSerializedFormatGibt Freihandeingaben an, die durch Codieren von ISF als Base64-Datenstrom beibehalten werden. Dieses Format wird bereitgestellt, damit Freihandeingaben direkt in einer XML-Datei (Extensible Markup Language) oder in einer HTML-Datei codiert werden können.
GifDieses Format definiert Freihandeingaben, die mithilfe einer GIF-Datei (Graphics Interchange Format) beibehalten werden, die ISF in Form von Metadaten enthält, die in die Datei eingebettet sind. So ist es möglich, Freihandeingaben in Anwendungen anzuzeigen, die nicht über die Funktion zur Freihandeingabe verfügen, während die Eingaben beim Wechsel zu einer Anwendung mit Freihandeingabe in vollem Umfang erhalten bleiben. Das Format ermöglicht nicht nur die Verwendung in Anwendungen mit und ohne Freihandfunktion, sondern ist bestens geeignet für den Transport von Freihandinhalt innerhalb einer HTML-Datei.
Base64GifDieses Format definiert Freihandeingaben, die mithilfe einer Base64-codierten verstärkten GIF-Datei beibehalten werden. Dieses Format wird bereitgestellt, wenn Freihandeingaben direkt in einer XML- oder HTML-Datei codiert und später in ein Bild konvertiert werden müssen. Dieses Format kann beispielsweise in einem XML-Format verwendet werden, das erstellt wurde, um alle Freihandinformationen zu speichern, und das verwendet wird, um HTML über XSLT (Extensible Stylesheet Language Transformations) zu erstellen.

 

Vollständiges Beispiel


//// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF
//// ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO
//// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
//// PARTICULAR PURPOSE.
////
//// Copyright (c) Microsoft Corporation. All rights reserved

// Windows Store app that demonstrates the use of the Windows.UI.Input.Inking APIs.

// Ink functionality is documented at http://go.microsoft.com/fwlink/?LinkID=260649.
// User interaction functionality is documented at http://go.microsoft.com/fwlink/?LinkID=260650.
// Ink APIs are documented at http://go.microsoft.com/fwlink/?LinkID=260652.
// Pointer APIs are documented at http://go.microsoft.com/fwlink/?LinkID=260653.

(function ()
{
    "use strict";

    //
    // Global variables
    //

        // UI object references.
        var inkCanvas;
        var inkContext;
        var modeMessage;
        var deviceMessage
        var statusMessage;

        // Create an ink manager.
        // InkManager is documented at http://go.microsoft.com/fwlink/?LinkID=260648.
        var inkManager = new Windows.UI.Input.Inking.InkManager();

        // Initial pointer values.
        var pointerId = -1;
        var pointerDeviceType = null;

        // Initial stroke property values.
        var strokeColor;
        var strokeWidth;

    //
    // End global variables
    //

    // Obtain reference to the specified element.
    function get(elementId)
    {
        return document.getElementById(elementId);
    }

    function initialize()
    {
        // Set up the UI.
        inkCanvas = get("inkCanvas");
        inkContext = inkCanvas.getContext("2d");

        inkContext.lineCap = "round";
        inkContext.lineKJoin = "round";

        inkCanvas.width = window.innerWidth - 10;
        inkCanvas.height = window.innerHeight * 0.5;

        deviceMessage = get("deviceMessage");
        deviceMessage.innerText = "Undefined";
        modeMessage = get("modeMessage");
        modeMessage.innerText = inkManager.mode;
        statusMessage = get("statusMessage");
        statusMessage.innerText = "No pointer input detected."

        // Set initial ink mode.
        drawStrokes();

        // Set default recognition language.
        if (!setRecognizerByName("Microsoft English (US) Handwriting Recognizer")) {
            statusMessage.innerText += "\nRecognition: Failed to find English (US) recognizer.";
        }
        else {
            statusMessage.innerText += "\nRecognition: English (US) recognizer.";
        }

        // Set up the handlers for input processing.
        inkCanvas.addEventListener("pointerdown", onPointerDown, false);
        inkCanvas.addEventListener("pointermove", onPointerMove, false);
        inkCanvas.addEventListener("pointerup", onPointerUp, false);

        get("save").addEventListener("click", saveStrokes, false);
        get("load").addEventListener("click", loadStrokes, false);
        get("draw").addEventListener("click", drawStrokes, false);
        get("select").addEventListener("click", selectStrokes, false);
        get("selectall").addEventListener("click", selectAllStrokes, false);
        get("erase").addEventListener("click", eraseStrokes, false);
        get("eraseAll").addEventListener("click", eraseAllStrokes, false);
        get("recognize").addEventListener("click", recognizeStrokes, false);
    }
    document.addEventListener("DOMContentLoaded", initialize, false);

    function getPointerDeviceType(pId)
    {
        var pointerDeviceType;
        var pointerPoint = Windows.UI.Input.PointerPoint.getCurrentPoint(pId);
        switch (pointerPoint.pointerDevice.pointerDeviceType)
        {
            case Windows.Devices.Input.PointerDeviceType.touch:
                pointerDeviceType = "Touch";
                break;

            case Windows.Devices.Input.PointerDeviceType.pen:
                pointerDeviceType = "Pen";
                break;

            case Windows.Devices.Input.PointerDeviceType.mouse:
                pointerDeviceType = "Mouse";
                break;
            default:
                pointerDeviceType = "Undefined";
        }
        deviceMessage.innerText = pointerDeviceType;
        return pointerDeviceType;
    }

    // Occurs when the pointer (touch, pen, mouse) is detected by the canvas.
    // Each stroke begins with onPointerDown.
    function onPointerDown(evt)
    {
        // Get the device type for the pointer input.
        pointerDeviceType = getPointerDeviceType(evt.pointerId);

        // Process pen and mouse (with left button) only. Reserve touch for manipulations.
        if ((pointerDeviceType === "Pen") || ((pointerDeviceType === "Mouse") && (evt.button === 0)))
        {
            statusMessage.innerText = pointerDeviceType + " pointer down: Start stroke. "

            // Process one pointer at a time.
            if (pointerId === -1)
            {
                var current = evt.currentPoint;

                // Start drawing the stroke.
                inkContext.beginPath();
                inkContext.lineWidth = strokeWidth;
                inkContext.strokeStyle = strokeColor;

                inkContext.moveTo(current.position.x, current.position.y);

                // Add current pointer to the ink manager (begin stroke).
                inkManager.processPointerDown(current);

                // The pointer id is used to restrict input processing to the current stroke.
                pointerId = evt.pointerId;
            }
        }
        else
        {
            // Process touch input.
        }
    }

    // Mouse: Occurs when the pointer moves.
    // Pen/Touch: Occurs at a steady rate (approx. 100 messages/second) whether the pointer moves or not.
    function onPointerMove(evt)
    {
        // Process pen and mouse (with left button) only. Reserve touch for manipulations.
        if ((pointerDeviceType === "Pen") || ((pointerDeviceType === "Mouse") && (evt.button === -1)))
        {
            statusMessage.innerText = pointerDeviceType + " pointer move: Draw stroke as lines. "
            // The pointer Id is used to restrict input processing to the current stroke.
            // pointerId is updated in onPointerDown().
            if (evt.pointerId === pointerId)
            {
                var current = evt.currentPoint;

                // Draw stroke in real time.
                inkContext.lineTo(current.rawPosition.x, current.rawPosition.y);
                inkContext.stroke();

                // Add current pointer to the ink manager (update stroke).
                inkManager.processPointerUpdate(current);
            }
        }
        else
        {
            // Process touch input.
        }
    }

    // Occurs when the pointer (touch, pen, mouse) is lifted from the canvas.
    // Each stroke ends with onPointerUp.
    function onPointerUp(evt)
    {
        // Process pen and mouse (with left button) only. Reserve touch for manipulations.
        if ((pointerDeviceType === "Pen") || ((pointerDeviceType === "Mouse") && (evt.button === 0)))
        {
            statusMessage.innerText = pointerDeviceType + " pointer up: Finish stroke. "
            if (evt.pointerId === pointerId) {
                // Add current pointer to the ink manager (end stroke).
                inkManager.processPointerUp(evt.currentPoint);

                // End live drawing.
                inkContext.closePath();

                // Render strokes using bezier curves.
                renderAllStrokes();

                // Reset pointer Id.
                pointerId = -1;
            }
        }
        else
        {
            // Process touch input.
        }
    }

    // Render all strokes using bezier curves instead of line segments.
    function renderAllStrokes()
    {
        statusMessage.innerText += "Render strokes as bezier curves."

        // Clear the drawing surface of existing strokes.
        inkContext.clearRect(0, 0, inkCanvas.width, inkCanvas.height);

        // Iterate through each stroke.
        inkManager.getStrokes().forEach(
            function (stroke)
            {
                inkContext.beginPath();
                if (stroke.selected) {
                    inkContext.lineWidth = stroke.drawingAttributes.size.width * 2;
                    inkContext.strokeStyle = "green";
                } else {
                    inkContext.lineWidth = stroke.drawingAttributes.size.width;
                    inkContext.strokeStyle = "black";
                }

                // Enumerate through each line segment of the stroke.
                var first = true;

                stroke.getRenderingSegments().forEach(
                    function (segment)
                    {
                        // Move to the starting screen location of the stroke.
                        if (first)
                        {
                            inkContext.moveTo(segment.position.x, segment.position.y);
                            first = false;
                        }
                        // Calculate the bezier curve for the segment.
                        else
                        {
                            inkContext.bezierCurveTo(segment.bezierControlPoint1.x,
                                                     segment.bezierControlPoint1.y,
                                                     segment.bezierControlPoint2.x,
                                                     segment.bezierControlPoint2.y,
                                                     segment.position.x, segment.position.y);
                        }
                    }
                );
                
                // Draw the stroke.
                inkContext.stroke();
                inkContext.closePath();
            }
        );
    }

    // Set up draw mode.
    function drawStrokes() {
        inkManager.mode = Windows.UI.Input.Inking.InkManipulationMode.inking;
        strokeColor = "black";
        strokeWidth = 2;
        modeMessage.innerText = inkManager.mode;
    }

    // Set up selection mode.
    function selectStrokes() {
        inkManager.mode = Windows.UI.Input.Inking.InkManipulationMode.selecting;
        strokeColor = "red";
        strokeWidth = 1;
        modeMessage.innerText = inkManager.mode;
    }

    // Set up erase mode.
    function eraseStrokes() {
        inkManager.mode = Windows.UI.Input.Inking.InkManipulationMode.erasing;
        strokeColor = "gold";
        strokeWidth = 1;
        modeMessage.innerText = inkManager.mode;
    }

    // Select all strokes handler.
    function selectAllStrokes() {
        inkManager.mode = Windows.UI.Input.Inking.InkManipulationMode.selecting;
        strokeColor = "red";
        strokeWidth = 1;
        modeMessage.innerText = "Select all strokes.";
        // Iterate through each stroke.
        inkManager.getStrokes().forEach(
            function (stroke) {
                stroke.selected = 1;
            }
            );
        renderAllStrokes();
    }

    // Select all strokes handler.
    function eraseAllStrokes() {
        inkManager.mode = Windows.UI.Input.Inking.InkManipulationMode.inking;
        strokeColor = "black";
        strokeWidth = 2;
        modeMessage.innerText = "Erase all strokes.";
        // Iterate through each stroke.
        inkManager.getStrokes().forEach(
            function (stroke) {
                stroke.selected = 1;
            }
            );
        inkManager.deleteSelected();
        renderAllStrokes();
    }

    // Save all strokes owned by inkManager.
    function saveStrokes()
    {
        // Ensure that strokes exist before calling saveAsync.
        if (inkManager.getStrokes().size > 0)
        {
            // Set up the file save screen.
            var savePicker = Windows.Storage.Pickers.FileSavePicker();
            savePicker.suggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.picturesLibrary;
            savePicker.fileTypeChoices.insert("GIF with embedded ISF", [".gif"]);
            savePicker.defaultFileExtension = ".gif";

            // Set up the stream.
            var saveStream = null;

            // Asynchronously save the ink data to the stream.
            savePicker.pickSaveFileAsync().done(
            function (file)
            {
                if (null !== file)
                {
                    file.openAsync(Windows.Storage.FileAccessMode.readWrite).then(
                        function (stream)
                        {
                            saveStream = stream;
                            return inkManager.saveAsync(saveStream);
                        }
                    ).then(
                        function ()
                        {
                            return saveStream.flushAsync(); 
                        },
                        function (e) {
                            // Override the standard saveAsync error with our own.
                            throw new Error("saveAsync");
                        }
                    ).done(
                        function ()
                        {
                            statusMessage.innerText = "Strokes saved as GIF with embedded ISF (.gif).";
                            saveStream.close();
                        },
                        function (e) {
                            statusMessage.innerText = "Save: " + e.toString();
                            // Close the stream if open.
                            if (saveStream) {
                                saveStream.close();
                            }
                        }
                    );
                }
            }
        );
        }
        else
        {
            statusMessage.innerText = "No strokes to save.";
        }
    }

    // Load strokes into an inkManager.
    function loadStrokes()
    {
        // Set up the file open screen.
        var openPicker = Windows.Storage.Pickers.FileOpenPicker();
        openPicker.suggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.picturesLibrary;
        openPicker.fileTypeFilter.replaceAll([".gif"]);

        // Set up the stream.
        var loadStream = null;

        // Asynchronously load the ink data from the stream.
        openPicker.pickSingleFileAsync().done(
            function (file)
            {
                if (null != file)
                {
                    file.openAsync(Windows.Storage.FileAccessMode.read).then(
                        function (stream) {
                            loadStream = stream;
                            return inkManager.loadAsync(loadStream);
                        }).done(
                            function()
                            {
                                var strokes = inkManager.getStrokes().length;
                                if (strokes === 0)
                                {
                                    statusMessage.innerText = "No strokes in file.";
                                }
                                else
                                {
                                    statusMessage.innerText = strokes + " strokes loaded.";
                                }
                                renderAllStrokes();
                                loadStream.close();
                            },
                            function (e)
                            {
                                statusMessage.innerText = "Load failed.";
                                if (loadStream)
                                {
                                    // Close the stream if open.
                                    loadStream.close();
                                }
                            });
                }
            });
    }

    /// <summary>
    /// Finds a specific recognizer, and sets the inkManager's default to that recognizer.
    /// Returns true if successful.
    /// </summary>
    /// <param name="recognizerName">The name of the handwriting recognizer.</param>
    function setRecognizerByName(recognizerName) {
        try {
            // recognizers is a normal JavaScript array
            var recognizers = inkManager.getRecognizers();
            for (var i = 0, len = recognizers.length; i < len; i++) {
                if (recognizerName === recognizers[i].name) {
                    inkManager.setDefaultRecognizer(recognizers[i]);
                    return true;
                }
            }
        }
        catch (e) {
            displayError("setRecognizerByName: " + e.toString());
        }
        return false;
    }

    /// <summary>
    /// Invoked when the "Handwriting recognition" button is pressed.
    /// The ink manager processes all strokes through recognizeAsync, which returns 
    /// the number of words detected and a set of recognition results for each word. 
    /// </summary>
    /// <param name="evt">The event object.</param>
    function recognizeStrokes(evt) {

        // Ensure ink strokes exist before calling recognizeAsync.
        if (inkManager.getStrokes().length > 0) {
            // recognizeAsync fails if other recognition tasks are in progress.
            try {
                // The ink manager is used to store the recognition results.
                // recognizeAsync has 3 modes: all | selected | recent.
                // For this example, we process all strokes.
                // recognizeAsync is documented at http://go.microsoft.com/fwlink/?LinkID=265172.
                inkManager.recognizeAsync(Windows.UI.Input.Inking.InkRecognitionTarget.all).done
                (
                    // The recognitionResult object returned by recognizeAsync exposes the 
                    // bounding rect, strokes, and text candidates for each word. 
                    // In this example, we simply display the word count and recognition results.
                    function (results) {
                        // recognizeAsync does not automatically update existing recognition results in the ink manager.
                        // updateRecognitionResults is documented at http://go.microsoft.com/fwlink/?LinkID=265175.
                        inkManager.updateRecognitionResults(results);

                        var x = inkManager.getRecognizers();

                        // Display the number of words returned in results.
                        statusMessage.innerText = "Words recognized: " + results.length.toString();

                        // Iterate through each word and display the ranked list of possible matches.
                        for (var i = 0; i < results.length; i++) {
                            statusMessage.innerText += "\nWord" + (i+1).toString() + ":";
                            var alts = results[i].getTextCandidates();
                            for (var j = 0; j < alts.length; j++) {
                                statusMessage.innerText += " " + alts[j].toString();
                            }
                        }
                    },
                    function (e) {
                        displayError("InkManager::recognizeAsync: " + e.toString());
                    }
                );
            }
            catch (e) {
                displayError("recognize: " + e.toString());
            }
        }
        else {
            statusMessage.innerText = "No strokes to recognize.";
        }
    }

    // Returns true if any strokes inside the ink manager are selected; false otherwise.
    function anySelected() {
        var strokes = inkManager.getStrokes();
        var len = strokes.length;
        for (var i = 0; i < len; i++) {
            if (strokes[i].selected) {
                return true;
            }
        }
        return false;
    }



})();


Verwandte Themen

Konzept
Reaktion auf Zeichenstift- und Eingabestifteingabe
Schnellstart: Erfassen von Freihanddaten
Referenz
Windows.Devices.Input
Windows.UI.Core
Windows.UI.Input
Windows.UI.Input.Inking
Beispiele (DOM)
Eingabe: Beispiel für die Behandlung von DOM-Zeigerereignissen
Beispiele (Windows Store-App-APIs) 
Eingabe: Beispiel für Gerätefunktionen
Eingabe: Freihandbeispiel
Eingabe: Vereinfachtes Freihandbeispiel

 

 

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