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6502bench/CommonWPF/MultiKeyInputGesture.cs

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/*
* Copyright 2019 faddenSoft
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
using System.Diagnostics;
using System.Text;
using System.Windows.Input;
namespace CommonWPF {
/// <summary>
/// Handle a multi-key input sequence for WPF windows.
/// </summary>
/// <remarks>
/// Also posted as https://stackoverflow.com/a/56452142/294248
///
/// Example:
/// {RoutedUICommand}.InputGestures.Add(
/// new MultiKeyInputGesture(new KeyGesture[] {
/// new KeyGesture(Key.H, ModifierKeys.Control, "Ctrl+H"),
/// new KeyGesture(Key.C, ModifierKeys.Control, "Ctrl+C")
/// }) );
/// </remarks>
public class MultiKeyInputGesture : InputGesture {
private const int MAX_PAUSE_MILLIS = 2000;
private InputGestureCollection mGestures = new InputGestureCollection();
private DateTime mLastWhen = DateTime.Now;
private int mCheckIdx;
private string mIdStr;
// On a successful match, the handler "eats" the final keypress. If you have multiple
// handlers, the ones that are called later won't see the non-matching key and will
// still be waiting. This can be a problem if the user types multiple multi-key
// sequences in rapid succession (or even not-so-rapid if you disable the timeout). To
// deal with this, all instances subscribe to this event, which fires when a match is
// found.
private delegate void GotMatchHandler(object sender, EventArgs e);
private static event GotMatchHandler sGotMatch;
/// <summary>
/// Constructor.
/// </summary>
/// <param name="keys">Sequence of keys to watch for.</param>
public MultiKeyInputGesture(KeyGesture[] keys) {
Debug.Assert(keys.Length > 0); // arguably also bad input if == 1
StringBuilder idSb = new StringBuilder();
// Grab a copy of the array contents.
foreach (KeyGesture kg in keys) {
mGestures.Add(kg);
idSb.Append(kg.DisplayString[kg.DisplayString.Length - 1]);
}
mIdStr = idSb.ToString();
sGotMatch += delegate(object sender, EventArgs e) {
mCheckIdx = 0;
};
}
/// <summary>
/// InputGesture interface. Tests an input event to see if it's part of a sequence.
/// </summary>
/// <param name="targetElement">Not used.</param>
/// <param name="inputEventArgs">Input event. Ignored if not a key event.</param>
/// <returns>True if the key matches and we're at the end of the sequence.</returns>
public override bool Matches(object targetElement, InputEventArgs inputEventArgs) {
if (!(inputEventArgs is KeyEventArgs)) {
// does this actually happen?
return false;
}
DateTime now = DateTime.Now;
if ((now - mLastWhen).TotalMilliseconds > MAX_PAUSE_MILLIS) {
//Debug.WriteLine("MKIG " + mIdStr + ": too long since last key (" +
// (now - mLastWhen).TotalMilliseconds + " ms");
mCheckIdx = 0;
}
mLastWhen = now;
if (((KeyEventArgs)inputEventArgs).IsRepeat) {
// ignore key-repeat noise (especially from modifiers)
return false;
}
if (!mGestures[mCheckIdx].Matches(null, inputEventArgs)) {
if (mCheckIdx > 0) {
//Debug.WriteLine("MKIG " + mIdStr + ": no match, resetting");
mCheckIdx = 0;
}
return false;
}
//Debug.WriteLine("MKIG " + mIdStr + ": matched gesture #" + mCheckIdx);
mCheckIdx++;
if (mCheckIdx == mGestures.Count) {
//Debug.WriteLine("MKIG " + mIdStr + ": match");
mCheckIdx = 0;
inputEventArgs.Handled = true;
// signal other instances
sGotMatch(this, null);
return true;
}
return false;
}
}
}