安卓用手指触碰屏幕缩放和移动,三指触碰屏幕旋转图片
2016-09-14 18:37
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原文链接
package com.multitouch.example; import android.app.Activity; import android.graphics.Matrix; import android.graphics.PointF; import android.os.Bundle; import android.util.FloatMath; import android.view.MotionEvent; import android.view.View; import android.view.View.OnTouchListener; import android.widget.ImageView; public class MultiTouch extends Activity implements OnTouchListener { // these matrices will be used to move and zoom image private Matrix matrix = new Matrix(); private Matrix savedMatrix = new Matrix(); // we can be in one of these 3 states private static final int NONE = 0; private static final int DRAG = 1; private static final int ZOOM = 2; private int mode = NONE; // remember some things for zooming private PointF start = new PointF(); private PointF mid = new PointF(); private float oldDist = 1f; private float d = 0f; private float newRot = 0f; private float[] lastEvent = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ImageView view = (ImageView) findViewById(R.id.imageView); view.setOnTouchListener(this); } public boolean onTouch(View v, MotionEvent event) { // handle touch events here ImageView view = (ImageView) v; switch (event.getAction() & MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_DOWN: savedMatrix.set(matrix); start.set(event.getX(), event.getY()); mode = DRAG; lastEvent = null; break; case MotionEvent.ACTION_POINTER_DOWN: oldDist = spacing(event); if (oldDist > 10f) { savedMatrix.set(matrix); midPoint(mid, event); mode = ZOOM; } lastEvent = new float[4]; lastEvent[0] = event.getX(0); lastEvent[1] = event.getX(1); lastEvent[2] = event.getY(0); lastEvent[3] = event.getY(1); d = rotation(event); break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_POINTER_UP: mode = NONE; lastEvent = null; break; case MotionEvent.ACTION_MOVE: if (mode == DRAG) { matrix.set(savedMatrix); float dx = event.getX() - start.x; float dy = event.getY() - start.y; matrix.postTranslate(dx, dy); } else if (mode == ZOOM) { float newDist = spacing(event); if (newDist > 10f) { matrix.set(savedMatrix); float scale = (newDist / oldDist); matrix.postScale(scale, scale, mid.x, mid.y); } if (lastEvent != null && event.getPointerCount() == 3) { newRot = rotation(event); float r = newRot - d; float[] values = new float[9]; matrix.getValues(values); float tx = values[2]; float ty = values[5]; float sx = values[0]; float xc = (view.getWidth() / 2) * sx; float yc = (view.getHeight() / 2) * sx; matrix.postRotate(r, tx + xc, ty + yc); } } break; } view.setImageMatrix(matrix); return true; } /** * Determine the space between the first two fingers */ private float spacing(MotionEvent event) { float x = event.getX(0) - event.getX(1); float y = event.getY(0) - event.getY(1); return FloatMath.sqrt(x * x + y * y); } /** * Calculate the mid point of the first two fingers */ private void midPoint(PointF point, MotionEvent event) { float x = event.getX(0) + event.getX(1); float y = event.getY(0) + event.getY(1); point.set(x / 2, y / 2); } /** * Calculate the degree to be rotated by. * * @param event * @return Degrees */ private float rotation(MotionEvent event) { double delta_x = (event.getX(0) - event.getX(1)); double delta_y = (event.getY(0) - event.getY(1)); double radians = Math.atan2(delta_y, delta_x); return (float) Math.toDegrees(radians); } }
<?xml version="1.0" encoding="utf-8"?> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent"> <ImageView android:id="@+id/imageView" android:layout_width="fill_parent" android:layout_height="fill_parent" android:src="@drawable/butterfly" android:scaleType="matrix" /> //设置这个属性很关键 </FrameLayout>
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