Android編程開發之多點觸摸(Multitouch)實現方法

本文實例講述了Android編程開發之多點觸摸(Multitouch)實現方法。分享給大家供大家參考，具體如下：

如果您對開發多點觸摸程序感興趣的話，那麼本文將是一個很好的開始，android應用程序開發中，多點觸摸不是那麼遙不可及，實現起來也很簡單，本例只需要兩個類就能實現多點觸摸。

首先來看看我們的視圖類MTView.java:

package com.ideasandroid.demo;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class MTView extends SurfaceView implements SurfaceHolder.Callback {
  private static final int MAX_TOUCHPOINTS = 10;
  private static final String START_TEXT = "請隨便觸摸屏幕進行測試";
  private Paint textPaint = new Paint();
  private Paint touchPaints[] = new Paint[MAX_TOUCHPOINTS];
  private int colors[] = new int[MAX_TOUCHPOINTS];
  private int width, height;
  private float scale = 1.0f;
  public MTView(Context context) {
    super(context);
    SurfaceHolder holder = getHolder();
    holder.addCallback(this);
    setFocusable(true); // 確保我們的View能獲得輸入焦點
    setFocusableInTouchMode(true); // 確保能接收到觸屏事件
    init();
  }
  private void init() {
    // 初始化10個不同顏色的畫筆
    textPaint.setColor(Color.WHITE);
    colors[0] = Color.BLUE;
    colors[1] = Color.RED;
    colors[2] = Color.GREEN;
    colors[3] = Color.YELLOW;
    colors[4] = Color.CYAN;
    colors[5] = Color.MAGENTA;
    colors[6] = Color.DKGRAY;
    colors[7] = Color.WHITE;
    colors[8] = Color.LTGRAY;
    colors[9] = Color.GRAY;
    for (int i = 0; i < MAX_TOUCHPOINTS; i++) {
      touchPaints[i] = new Paint();
      touchPaints[i].setColor(colors[i]);
    }
  }
  /*
   * 處理觸屏事件
   */
  @Override
  public boolean onTouchEvent(MotionEvent event) {
    // 獲得屏幕觸點數量
    int pointerCount = event.getPointerCount();
    if (pointerCount > MAX_TOUCHPOINTS) {
      pointerCount = MAX_TOUCHPOINTS;
    }
    // 鎖定Canvas,開始進行相應的界面處理
    Canvas c = getHolder().lockCanvas();
    if (c != null) {
      c.drawColor(Color.BLACK);
      if (event.getAction() == MotionEvent.ACTION_UP) {
        // 當手離開屏幕時，清屏
      } else {
        // 先在屏幕上畫一個十字，然後畫一個圓
        for (int i = 0; i < pointerCount; i++) {
          // 獲取一個觸點的坐標，然後開始繪制
          int id = event.getPointerId(i);
          int x = (int) event.getX(i);
          int y = (int) event.getY(i);
          drawCrosshairsAndText(x, y, touchPaints[id], i, id, c);
        }
        for (int i = 0; i < pointerCount; i++) {
          int id = event.getPointerId(i);
          int x = (int) event.getX(i);
          int y = (int) event.getY(i);
          drawCircle(x, y, touchPaints[id], c);
        }
      }
      // 畫完後，unlock
      getHolder().unlockCanvasAndPost(c);
    }
    return true;
  }
  /**
   * 畫十字及坐標信息
   *
   * @param x
   * @param y
   * @param paint
   * @param ptr
   * @param id
   * @param c
   */
  private void drawCrosshairsAndText(int x, int y, Paint paint, int ptr,
      int id, Canvas c) {
    c.drawLine(0, y, width, y, paint);
    c.drawLine(x, 0, x, height, paint);
    int textY = (int) ((15 + 20 * ptr) * scale);
    c.drawText("x" + ptr + "=" + x, 10 * scale, textY, textPaint);
    c.drawText("y" + ptr + "=" + y, 70 * scale, textY, textPaint);
    c.drawText("id" + ptr + "=" + id, width - 55 * scale, textY, textPaint);
  }
  /**
   * 畫圓
   *
   * @param x
   * @param y
   * @param paint
   * @param c
   */
  private void drawCircle(int x, int y, Paint paint, Canvas c) {
    c.drawCircle(x, y, 40 * scale, paint);
  }
  /*
   * 進入程序時背景畫成黑色，然後把“START_TEXT”寫到屏幕
   */
  public void surfaceChanged(SurfaceHolder holder, int format, int width,
      int height) {
    this.width = width;
    this.height = height;
    if (width > height) {
      this.scale = width / 480f;
    } else {
      this.scale = height / 480f;
    }
    textPaint.setTextSize(14 * scale);
    Canvas c = getHolder().lockCanvas();
    if (c != null) {
      // 背景黑色
      c.drawColor(Color.BLACK);
      float tWidth = textPaint.measureText(START_TEXT);
      c.drawText(START_TEXT, width / 2 - tWidth / 2, height / 2,
          textPaint);
      getHolder().unlockCanvasAndPost(c);
    }
  }
  public void surfaceCreated(SurfaceHolder holder) {
  }
  public void surfaceDestroyed(SurfaceHolder holder) {
  }
}

代碼中都做了相應的注釋，這裡就不多說。

接下來看看我們的Activity，MultitouchVisible.java

package com.ideasandroid.demo;
import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;
public class MultitouchVisible extends Activity {
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //隱藏標題欄
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    //設置成全屏
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
        WindowManager.LayoutParams.FLAG_FULLSCREEN);
    //設置為上面的MTView
    setContentView(new MTView(this));
  }
}

更多關於Android相關內容感興趣的讀者可查看本站專題：《Android開發入門與進階教程》、《Android編程之activity操作技巧總結》、《Android視圖View技巧總結》、《Android操作SQLite數據庫技巧總結》、《Android操作json格式數據技巧總結》、《Android數據庫操作技巧總結》、《Android文件操作技巧匯總》、《Android編程開發之SD卡操作方法匯總》、《Android資源操作技巧匯總》及《Android控件用法總結》

希望本文所述對大家Android程序設計有所幫助。