我尝试实现一个多点触控程序来测试和了解 Android 的工作原理。我已经尝试过以下代码,但是当我运行它时,屏幕上只能识别十个可能的 ID 中的四个,其他行只是我设置的默认值。
这是代码:-
package com.example.chester;
import android.annotation.TargetApi;
import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.TextView;
@TargetApi(8)
public class MultiTouchTest extends Activity implements OnTouchListener {
StringBuilder builder = new StringBuilder();
TextView textView;
float[] x = new float[10];
float[] y = new float[10];
boolean[] touched = new boolean[10];
int[] id = new int[10];
private void updateTextView() {
builder.setLength(0);
for (int i = 0; i < 10; i++) {
builder.append(touched[i]);
builder.append(", ");
builder.append(id[i]);
builder.append(", ");
builder.append(x[i]);
builder.append(", ");
builder.append(y[i]);
builder.append("\n");
}
textView.setText(builder.toString());
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
textView = new TextView(this);
textView.setText("Touch and drag (multiple fingers supported)!");
textView.setOnTouchListener(this);
setContentView(textView);
for (int i = 0; i < 10; i++) {
id[i] = -1;
}
updateTextView();
}
public boolean onTouch(View v, MotionEvent event) {
int action = event.getAction() & MotionEvent.ACTION_MASK;
int pointerIndex = (event.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
int pointerCount = event.getPointerCount();
for (int i = 0; i < 10; i++) {
if (i >= pointerCount) {
touched[i] = false;
id[i] = -1;
continue;
}
if (event.getAction() != MotionEvent.ACTION_MOVE
&& i != pointerIndex) {
continue;
}
int pointerId = event.getPointerId(i);
switch (action) {
case MotionEvent.ACTION_DOWN:
case MotionEvent.ACTION_POINTER_DOWN:
touched[i] = true;
id[i] = pointerId;
x[i] = (int) event.getX(i);
y[i] = (int) event.getY(i);
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
case MotionEvent.ACTION_OUTSIDE:
case MotionEvent.ACTION_CANCEL:
touched[i] = false;
id[i] = -1;
x[i] = (int) event.getX(i);
y[i] = (int) event.getY(i);
break;
case MotionEvent.ACTION_MOVE:
touched[i] = true;
id[i] = pointerId;
x[i] = (int) event.getX(i);
y[i] = (int) event.getY(i);
break;
}
}
updateTextView();
return true;
}
}
编辑:我使用的是 Android 4.0.3 的 HTC Sensation
最佳答案
您可以进行的触摸次数取决于设备(取决于设备的制造方式和使用的部件),而 Android(作为移动操作系统)最多支持 10 次。
关于java - MultiTouch - 为什么最多只有四个手指,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/21007893/