Come cancellare i tratti input penna (HTML)
[ Questo articolo è rivolto agli sviluppatori per Windows 8.x e Windows Phone 8.x che realizzano app di Windows Runtime. Gli sviluppatori che usano Windows 10 possono vedere Documentazione aggiornata ]
In questo argomento viene illustrato come cancellare i tratti input penna in un'app di Windows Store in JavaScript.
Aggiornamenti per Windows 8.1: In Windows 8.1 vengono introdotti diversi aggiornamenti e miglioramenti alle API di input tramite puntatore. Per altre informazioni, vedi Modifiche delle API per Windows 8.1.
Poiché un'app che supporta l'input penna deve distinguere tra l'input destinato a disegnare tratti input penna e l'input destinato a cancellare tratti input penna, questa operazione viene solitamente implementata come uno stato modale.
La cancellazione può essere attivata in vari modi: tramite un comando sulla barra dell'app, la punta della penna per cancellare o il pulsante della penna (inclusi i pulsanti interruttore della penna). I pulsanti della penna sono utili poiché riducono i passaggi continui tra la superficie di disegno e la barra dell'app. La tua applicazione dovrà supportare tutte le opzioni e le funzionalità del dispositivo.
Di seguito è illustrata una superficie di disegno con un solo pannello Canvas usato per accettare sia tratti di input penna e tratti di cancellazione in base a uno stati di input specificato dall'utente.
InkManipulationMode specifica il comportamento di tutti i nuovi tratti disegnati dall'utente. In modalità erasing i nuovi tratti vengono visualizzati sulla superficie di disegno, ma non ne viene eseguito il rendering e quindi scompaiono quando l'utente solleva la penna. In tratti esistenti vengono cancellati quando l'utente li interseca con un tratto di cancellazione. Questo è il comportamento predefinito della piattaforma di input penna Windows 8.
Cosa sapere
Tecnologie
Prerequisiti
Questo argomento si basa suGuida introduttiva: Acquisizione dei dati di input penna.
Diamo per scontato che tu sappia creare un'app di Windows Store di base in JavaScript in cui viene usato il modello Libreria Windows per JavaScript.
- Per informazioni sulla creazione della tua prima app di Windows Store, vedi Creazione della prima app di Windows Store in JavaScript.
- Per informazioni sull'uso di oggetti e controlli WinJS, vedi Guida introduttiva: Aggiunta di controlli e stili WinJS.
Istruzioni
Passaggio 1: Creare un gestore di input penna
Inizializza un oggetto InkManager per l'elaborazione e la modifica dei dati correlati all'input penna ottenuti dall'input del puntatore.
// Create an ink manager.
// InkManager is documented at https://go.microsoft.com/fwlink/?LinkID=260648.
var inkManager = new Windows.UI.Input.Inking.InkManager();
Passaggio 2: Definire le impostazioni del tratto iniziali
Ogni InkManipulationMode dispone di impostazioni del tratto univoche per indicare all'utente quale modalità è attiva. Per impostazione predefinita, questo esempio inizia in modalità inking con le impostazioni del tratto specificate.
// Initial stroke property values.
var strokeColor;
var strokeWidth;
Passaggio 3: Abilitare la selezione della modalità
Fornisci un modo con cui l'utente possa scegliere InkManipulationMode.
Per prima cosa dichiariamo un set di pulsanti di modalità.
<body>
<div id="applicationTitle">Ink sample</div>
<div>
<canvas id="inkCanvas"></canvas>
<div>
<button id="load">Load</button>
<button id="save">Save</button>
<button id="draw">Draw</button>
<button id="select">Select</button>
<button id="selectall">Select all</button>
<button id="erase">Erase</button>
<button id="eraseAll">Erase all</button>
<button id="recognize" value="selected">Handwriting recognition</button>
</div>
</div>
<div id="modeMessage"></div>
<div id="deviceMessage"></div>
<div id="statusMessage"></div>
</body>
Quindi dichiariamo un listener di eventi.
get("erase").addEventListener("click", eraseStrokes, false);
Infine definiamo le impostazioni del tratto nel gestore dell'evento click per ogni pulsante di modalità.
// 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;
}
Passaggio 4: Cancellare tutti i tratti
Crea un'opzione che consenta di cancellare tutti i tratti contemporaneamente.
// 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();
}
Passaggio 5: Eseguire di nuovo il rendering dei tratti dopo la cancellazione
La funzione renderAllStrokes usa inkManager per elaborare ogni segmento di tratto tramite il metodo bezierCurveTo. Ogni tratto viene ridisegnato usando le impostazioni appropriate. Un tratto cancellato viene eliminato dalla raccolta di tratti InkManager e non è più disponibile nel canvas.
// 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();
}
);
}
Esempio completo
//// 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 https://go.microsoft.com/fwlink/?LinkID=260649.
// User interaction functionality is documented at https://go.microsoft.com/fwlink/?LinkID=260650.
// Ink APIs are documented at https://go.microsoft.com/fwlink/?LinkID=260652.
// Pointer APIs are documented at https://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 https://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 https://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 https://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;
}
})();
Argomenti correlati
Informazioni concettuali
Risposta all'input stilo e penna
Guida introduttiva: Acquisizione dei dati di input penna
Informazioni di riferimento
Esempi (DOM)
Input: Esempio di gestione degli eventi relativi al puntatore DOM
Esempi (API di app di Windows Store)