Android透过手势实现的缩放处理
Android通过手势实现的缩放处理
01 import android.app.Activity;
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import android.content.Context;
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import android.graphics.Canvas;
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import android.graphics.Color;
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import android.graphics.Paint;
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import android.os.Bundle;
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import android.util.DisplayMetrics;
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import android.view.MotionEvent;
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import android.view.View;
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/** |
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* ...
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*
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* @author vlinux
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*
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*/
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public class MultiTouchTestActivity extends Activity {
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/** Called when the activity is first created. */
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@Override
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public void onCreate(Bundle savedInstanceState) {
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super.onCreate(savedInstanceState);
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// setContentView(R.layout.main);
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View view = new MultiTouchView(this);
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setContentView(view);
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}
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class MultiTouchView extends View {
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private float x1;
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private float y1;
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private float x2;
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private float y2;
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public MultiTouchView(Context context) {
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super(context);
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// TODO Auto-generated constructor stub
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}
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@Override
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public boolean onTouchEvent(MotionEvent event) {
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// TODO Auto-generated method stub
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float size = event.getSize();
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int szi = (int) size;
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int dxi = szi >> 12;
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int dyit = ((1 << 12) - 1);
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int dyi = szi & dyit;
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DisplayMetrics metrics = getResources().getDisplayMetrics();
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float dx = metrics.widthPixels * dxi / (float) dyit;
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float dy = metrics.heightPixels * dyi / (float) dyit;
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x1 = event.getX();
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y1 = event.getY();
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x2 = x1 + dx;
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y2 = y1 + dy;
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invalidate();
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return true;
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}
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@Override
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protected void onDraw(Canvas canvas) {
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// TODO Auto-generated method stub
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super.onDraw(canvas);
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float r = (float) Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2)
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* (y1 - y2)) / 2;
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r = 50 >= r ? 50 : r;
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Paint paint = new Paint();
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paint.setColor(Color.BLUE);
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canvas.drawCircle(x1, y1, r, paint);
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}
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}
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} |