¿Podemos utilizar el detector de escala de gestos para pinch zoom en Android?

¿Podemos utilizar el detector de escala de gestos para pinch zoom en Android?

6 Solutions collect form web for “¿Podemos utilizar el detector de escala de gestos para pinch zoom en Android?”

Puedes usar esto

import android.content.Context; import android.graphics.Canvas; import android.graphics.drawable.BitmapDrawable; import android.util.AttributeSet; import android.util.Log; import android.view.MotionEvent; import android.view.ScaleGestureDetector; import android.view.View; public class MyImageView extends View { private static final int INVALID_POINTER_ID = -1; private Drawable mImage; private float mPosX; private float mPosY; private float mLastTouchX; private float mLastTouchY; private int mActivePointerId = INVALID_POINTER_ID; private ScaleGestureDetector mScaleDetector; private float mScaleFactor = 1.f; public MyImageView(Context context) { this(context, null, 0); mImage=act.getResources().getDrawable(context.getResources().getIdentifier("imagename", "drawable", "packagename")); mImage.setBounds(0, 0, mImage.getIntrinsicWidth(), mImage.getIntrinsicHeight()); } public MyImageView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public MyImageView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); mScaleDetector = new ScaleGestureDetector(context, new ScaleListener()); } @Override public boolean onTouchEvent(MotionEvent ev) { // Let the ScaleGestureDetector inspect all events. mScaleDetector.onTouchEvent(ev); final int action = ev.getAction(); switch (action & MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_DOWN: { final float x = ev.getX(); final float y = ev.getY(); mLastTouchX = x; mLastTouchY = y; mActivePointerId = ev.getPointerId(0); break; } case MotionEvent.ACTION_MOVE: { final int pointerIndex = ev.findPointerIndex(mActivePointerId); final float x = ev.getX(pointerIndex); final float y = ev.getY(pointerIndex); // Only move if the ScaleGestureDetector isn't processing a gesture. if (!mScaleDetector.isInProgress()) { final float dx = x - mLastTouchX; final float dy = y - mLastTouchY; mPosX += dx; mPosY += dy; invalidate(); } mLastTouchX = x; mLastTouchY = y; break; } case MotionEvent.ACTION_UP: { mActivePointerId = INVALID_POINTER_ID; break; } case MotionEvent.ACTION_CANCEL: { mActivePointerId = INVALID_POINTER_ID; break; } case MotionEvent.ACTION_POINTER_UP: { final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT; final int pointerId = ev.getPointerId(pointerIndex); if (pointerId == mActivePointerId) { // This was our active pointer going up. Choose a new // active pointer and adjust accordingly. final int newPointerIndex = pointerIndex == 0 ? 1 : 0; mLastTouchX = ev.getX(newPointerIndex); mLastTouchY = ev.getY(newPointerIndex); mActivePointerId = ev.getPointerId(newPointerIndex); } break; } } return true; } @Override public void onDraw(Canvas canvas) { super.onDraw(canvas); canvas.save(); Log.d("DEBUG", "X: "+mPosX+" Y: "+mPosY); canvas.translate(mPosX, mPosY); canvas.scale(mScaleFactor, mScaleFactor); mImage.draw(canvas); canvas.restore(); } private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener { @Override public boolean onScale(ScaleGestureDetector detector) { mScaleFactor *= detector.getScaleFactor(); // Don't let the object get too small or too large. mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 10.0f)); invalidate(); return true; } } } 

Para llamar a esto en su activity.setContentView(new MyImageView(this));

ScaleGestureDetector está disponible a partir de Android 2.2 (también conocido como Froyo, API nivel 8). Ver: http://android-developers.blogspot.com/2010/06/making-sense-of-multitouch.html

En 2.0 / 2.1, usted no tiene ScaleGestureDetector, pero usted puede proporcionar pinch-to-zoom usando la entrada de blog ZDNet de Ed Burnette que Pieter888 vinculado a lo anterior: http://www.zdnet.com/blog/burnette/how -para-usar-multi-tacto-en-androide-2-parte-6-implementar-el-pinch-zoom-gesture / 1847

Puede crear una clase reutilizable que implemente OnTouchListener para lograr esto.

 public class MyScaleGestures implements OnTouchListener, OnScaleGestureListener { private View view; private ScaleGestureDetector gestureScale; private float scaleFactor = 1; public StandardGestures(Context c){ gestureScale = new ScaleGestureDetector(c, this); } @Override public boolean onTouch(View view, MotionEvent event) { this.view = view; gestureScale.onTouchEvent(event); return true; } @Override public boolean onScale(ScaleGestureDetector detector) { scaleFactor *= detector.getScaleFactor(); scaleFactor = (scaleFactor < 1 ? 1 : scaleFactor); // prevent our view from becoming too small // scaleFactor = ((float)((int)(scaleFactor * 100))) / 100; // Change precision to help with jitter when user just rests their fingers // view.setScaleX(scaleFactor); view.setScaleY(scaleFactor); return true; } @Override public boolean onScaleBegin(ScaleGestureDetector detector) { inScale = true; return true; } @Override public void onScaleEnd(ScaleGestureDetector detector) { inScale = false; } } 

A continuación, asignarla como OnTouchListener su View .

 myView.setOnTouchListener(new MyScaleGestures(context)); 

Si desea agregar una capacidad de desplazamiento a la View , deberá implementar onScroll . Puede agregar esta anulación a la clase MyScaleGestures para lograr esto.

 @Override public boolean onScroll(MotionEvent event1, MotionEvent event2, float x, float y) { float newX = view.getX(); float newY = view.getY(); if(!inScale){ newX -= x; newY -= y; } WindowManager wm = (WindowManager) view.getContext().getSystemService(Context.WINDOW_SERVICE); Display d = wm.getDefaultDisplay(); Point p = new Point(); d.getSize(p); if (newX > (view.getWidth() * scaleFactor - px) / 2){ newX = (view.getWidth() * scaleFactor - px) / 2; } else if (newX < -((view.getWidth() * scaleFactor - px) / 2)){ newX = -((view.getWidth() * scaleFactor - px) / 2); } if (newY > (view.getHeight() * scaleFactor - py) / 2){ newY = (view.getHeight() * scaleFactor - py) / 2; } else if (newY < -((view.getHeight() * scaleFactor - py) / 2)){ newY = -((view.getHeight() * scaleFactor - py) / 2); } view.setX(newX); view.setY(newY); return true; } 

En realidad hay una biblioteca que utiliza esta clase sólo para el zoom de las imágenes.

Se llama " TouchImageView "

Sí podemos aquí es el código de ejemplo donde onPinch () y onZoom () son acciones para ser implementar por su cuenta

 public class simpleOnScaleGestureListener extends SimpleOnScaleGestureListener { @Override public boolean onScale(ScaleGestureDetector detector) { startScale = detector.getScaleFactor(); return true; } @Override public boolean onScaleBegin(ScaleGestureDetector detector) { return true; } @Override public void onScaleEnd(ScaleGestureDetector detector) { endScale = detector.getScaleFactor(); // if ((startScale - endScale) > 0.0100 // || (endScale - startScale) > 0.0100) { if (startScale > endScale) { Log.i("onScaleEnd", "Pinch Dection"); onPinch(); } else if (startScale < endScale) { Log.i("onScaleEnd", "Zoom Dection"); onZoom(); } // } } } 

TouchImageView

 public class TouchImageView extends ImageView { Matrix matrix; // We can be in one of these 3 states static final int NONE = 0; static final int DRAG = 1; static final int ZOOM = 2; int mode = NONE; // Remember some things for zooming PointF last = new PointF(); PointF start = new PointF(); float minScale = 1f; float maxScale = 3f; float[] m; int viewWidth, viewHeight; static final int CLICK = 3; float saveScale = 1f; protected float origWidth, origHeight; int oldMeasuredWidth, oldMeasuredHeight; ScaleGestureDetector mScaleDetector; Context context; public TouchImageView(Context context) { super(context); sharedConstructing(context); } public TouchImageView(Context context, AttributeSet attrs) { super(context, attrs); sharedConstructing(context); } private void sharedConstructing(Context context) { super.setClickable(true); this.context = context; mScaleDetector = new ScaleGestureDetector(context, new ScaleListener()); matrix = new Matrix(); m = new float[9]; setImageMatrix(matrix); setScaleType(ScaleType.MATRIX); setOnTouchListener(new OnTouchListener() { @Override public boolean onTouch(View v, MotionEvent event) { mScaleDetector.onTouchEvent(event); PointF curr = new PointF(event.getX(), event.getY()); switch (event.getAction()) { case MotionEvent.ACTION_DOWN: last.set(curr); start.set(last); mode = DRAG; break; case MotionEvent.ACTION_MOVE: if (mode == DRAG) { float deltaX = curr.x - last.x; float deltaY = curr.y - last.y; float fixTransX = getFixDragTrans(deltaX, viewWidth, origWidth * saveScale); float fixTransY = getFixDragTrans(deltaY, viewHeight, origHeight * saveScale); matrix.postTranslate(fixTransX, fixTransY); fixTrans(); last.set(curr.x, curr.y); } break; case MotionEvent.ACTION_UP: mode = NONE; int xDiff = (int) Math.abs(curr.x - start.x); int yDiff = (int) Math.abs(curr.y - start.y); if (xDiff < CLICK && yDiff < CLICK) performClick(); break; case MotionEvent.ACTION_POINTER_UP: mode = NONE; break; } setImageMatrix(matrix); invalidate(); return true; // indicate event was handled } }); } public void setMaxZoom(float x) { maxScale = x; } private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener { @Override public boolean onScaleBegin(ScaleGestureDetector detector) { mode = ZOOM; return true; } @Override public boolean onScale(ScaleGestureDetector detector) { float mScaleFactor = detector.getScaleFactor(); float origScale = saveScale; saveScale *= mScaleFactor; if (saveScale > maxScale) { saveScale = maxScale; mScaleFactor = maxScale / origScale; } else if (saveScale < minScale) { saveScale = minScale; mScaleFactor = minScale / origScale; } if (origWidth * saveScale <= viewWidth || origHeight * saveScale <= viewHeight) matrix.postScale(mScaleFactor, mScaleFactor, viewWidth / 2, viewHeight / 2); else matrix.postScale(mScaleFactor, mScaleFactor, detector.getFocusX(), detector.getFocusY()); fixTrans(); return true; } } void fixTrans() { matrix.getValues(m); float transX = m[Matrix.MTRANS_X]; float transY = m[Matrix.MTRANS_Y]; float fixTransX = getFixTrans(transX, viewWidth, origWidth * saveScale); float fixTransY = getFixTrans(transY, viewHeight, origHeight * saveScale); if (fixTransX != 0 || fixTransY != 0) matrix.postTranslate(fixTransX, fixTransY); } float getFixTrans(float trans, float viewSize, float contentSize) { float minTrans, maxTrans; if (contentSize <= viewSize) { minTrans = 0; maxTrans = viewSize - contentSize; } else { minTrans = viewSize - contentSize; maxTrans = 0; } if (trans < minTrans) return -trans + minTrans; if (trans > maxTrans) return -trans + maxTrans; return 0; } float getFixDragTrans(float delta, float viewSize, float contentSize) { if (contentSize <= viewSize) { return 0; } return delta; } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); viewWidth = MeasureSpec.getSize(widthMeasureSpec); viewHeight = MeasureSpec.getSize(heightMeasureSpec); // // Rescales image on rotation // if (oldMeasuredHeight == viewWidth && oldMeasuredHeight == viewHeight || viewWidth == 0 || viewHeight == 0) return; oldMeasuredHeight = viewHeight; oldMeasuredWidth = viewWidth; if (saveScale == 1) { //Fit to screen. float scale; Drawable drawable = getDrawable(); if (drawable == null || drawable.getIntrinsicWidth() == 0 || drawable.getIntrinsicHeight() == 0) return; int bmWidth = drawable.getIntrinsicWidth(); int bmHeight = drawable.getIntrinsicHeight(); Log.e("bmSize", "bmWidth: " + bmWidth + " bmHeight : " + bmHeight); float scaleX = (float) viewWidth / (float) bmWidth; float scaleY = (float) viewHeight / (float) bmHeight; scale = Math.min(scaleX, scaleY); matrix.setScale(scale, scale); // Center the image float redundantYSpace = (float) viewHeight - (scale * (float) bmHeight); float redundantXSpace = (float) viewWidth - (scale * (float) bmWidth); redundantYSpace /= (float) 2; redundantXSpace /= (float) 2; matrix.postTranslate(redundantXSpace, redundantYSpace); origWidth = viewWidth - 2 * redundantXSpace; origHeight = viewHeight - 2 * redundantYSpace; setImageMatrix(matrix); } fixTrans(); } } 

MainActivity.java

 public class SecondActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_second); TouchImageView img = new TouchImageView(this); img.setImageResource(R.drawable.ic_launcher); img.setMaxZoom(4f); setContentView(img); } } 
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