Pinch zoom in android 2.1

El siguiente código funciona muy bien! Sólo tienes que copiar y pegar:

import android.content.Context; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Matrix; import android.graphics.Paint; import android.graphics.PointF; import android.os.Handler; import android.util.AttributeSet; import android.util.FloatMath; import android.util.Log; import android.view.GestureDetector; import android.view.MotionEvent; import android.view.View; import android.view.GestureDetector.SimpleOnGestureListener; public class ZoomableImageView extends View { private static final String TAG = "ZoomableImageView"; private Bitmap imgBitmap = null; private int containerWidth; private int containerHeight; Paint background; //Matrices will be used to move and zoom image Matrix matrix = new Matrix(); Matrix savedMatrix = new Matrix(); PointF start = new PointF(); float currentScale; float curX; float curY; //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; //For animating stuff float targetX; float targetY; float targetScale; float targetScaleX; float targetScaleY; float scaleChange; float targetRatio; float transitionalRatio; float easing = 0.2f; boolean isAnimating = false; float scaleDampingFactor = 0.5f; //For pinch and zoom float oldDist = 1f; PointF mid = new PointF(); private Handler mHandler = new Handler(); float minScale; float maxScale = 8.0f; float wpRadius = 25.0f; float wpInnerRadius = 20.0f; float screenDensity; private GestureDetector gestureDetector; public static final int DEFAULT_SCALE_FIT_INSIDE = 0; public static final int DEFAULT_SCALE_ORIGINAL = 1; private int defaultScale; public int getDefaultScale() { return defaultScale; } public void setDefaultScale(int defaultScale) { this.defaultScale = defaultScale; } public ZoomableImageView(Context context) { super(context); setFocusable(true); setFocusableInTouchMode(true); screenDensity = context.getResources().getDisplayMetrics().density; initPaints(); gestureDetector = new GestureDetector(new MyGestureDetector()); } public ZoomableImageView(Context context, AttributeSet attrs) { super(context, attrs); screenDensity = context.getResources().getDisplayMetrics().density; initPaints(); gestureDetector = new GestureDetector(new MyGestureDetector()); defaultScale = ZoomableImageView.DEFAULT_SCALE_FIT_INSIDE; } private void initPaints() { background = new Paint(); } @Override protected void onSizeChanged(int width, int height, int oldWidth, int oldHeight) { super.onSizeChanged(width, height, oldWidth, oldHeight); //Reset the width and height. Will draw bitmap and change containerWidth = width; containerHeight = height; if(imgBitmap != null) { int imgHeight = imgBitmap.getHeight(); int imgWidth = imgBitmap.getWidth(); float scale; int initX = 0; int initY = 0; if(defaultScale == ZoomableImageView.DEFAULT_SCALE_FIT_INSIDE) { if(imgWidth > containerWidth) { scale = (float)containerWidth / imgWidth; float newHeight = imgHeight * scale; initY = (containerHeight - (int)newHeight)/2; matrix.setScale(scale, scale); matrix.postTranslate(0, initY); } else { scale = (float)containerHeight / imgHeight; float newWidth = imgWidth * scale; initX = (containerWidth - (int)newWidth)/2; matrix.setScale(scale, scale); matrix.postTranslate(initX, 0); } curX = initX; curY = initY; currentScale = scale; minScale = scale; } else { if(imgWidth > containerWidth) { initY = (containerHeight - (int)imgHeight)/2; matrix.postTranslate(0, initY); } else { initX = (containerWidth - (int)imgWidth)/2; matrix.postTranslate(initX, 0); } curX = initX; curY = initY; currentScale = 1.0f; minScale = 1.0f; } invalidate(); } } @Override protected void onDraw(Canvas canvas) { if(imgBitmap != null && canvas != null) { canvas.drawBitmap(imgBitmap, matrix, background); } } //Checks and sets the target image x and y co-ordinates if out of bounds private void checkImageConstraints() { if(imgBitmap == null) { return; } float[] mvals = new float[9]; matrix.getValues(mvals); currentScale = mvals[0]; if(currentScale < minScale) { float deltaScale = minScale / currentScale; float px = containerWidth/2; float py = containerHeight/2; matrix.postScale(deltaScale, deltaScale, px, py); invalidate(); } matrix.getValues(mvals); currentScale = mvals[0]; curX = mvals[2]; curY = mvals[5]; int rangeLimitX = containerWidth - (int)(imgBitmap.getWidth() * currentScale); int rangeLimitY = containerHeight - (int)(imgBitmap.getHeight() * currentScale); boolean toMoveX = false; boolean toMoveY = false; if(rangeLimitX < 0) { if(curX > 0) { targetX = 0; toMoveX = true; } else if(curX < rangeLimitX) { targetX = rangeLimitX; toMoveX = true; } } else { targetX = rangeLimitX / 2; toMoveX = true; } if(rangeLimitY < 0) { if(curY > 0) { targetY = 0; toMoveY = true; } else if(curY < rangeLimitY) { targetY = rangeLimitY; toMoveY = true; } } else { targetY = rangeLimitY / 2; toMoveY = true; } if(toMoveX == true || toMoveY == true) { if(toMoveY == false) { targetY = curY; } if(toMoveX == false) { targetX = curX; } //Disable touch event actions isAnimating = true; //Initialize timer mHandler.removeCallbacks(mUpdateImagePositionTask); mHandler.postDelayed(mUpdateImagePositionTask, 100); } } @Override public boolean onTouchEvent(MotionEvent event) { if(gestureDetector.onTouchEvent(event)) { return true; } if(isAnimating == true) { return true; } //Handle touch events here float[] mvals = new float[9]; switch(event.getAction() & MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_DOWN: if(isAnimating == false) { savedMatrix.set(matrix); start.set(event.getX(), event.getY()); mode = DRAG; } break; case MotionEvent.ACTION_POINTER_DOWN: oldDist = spacing(event); if(oldDist > 10f) { savedMatrix.set(matrix); midPoint(mid, event); mode = ZOOM; } break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_POINTER_UP: mode = NONE; matrix.getValues(mvals); curX = mvals[2]; curY = mvals[5]; currentScale = mvals[0]; if(isAnimating == false) { checkImageConstraints(); } break; case MotionEvent.ACTION_MOVE: if(mode == DRAG && isAnimating == false) { matrix.set(savedMatrix); float diffX = event.getX() - start.x; float diffY = event.getY() - start.y; matrix.postTranslate(diffX, diffY); matrix.getValues(mvals); curX = mvals[2]; curY = mvals[5]; currentScale = mvals[0]; } else if(mode == ZOOM && isAnimating == false) { float newDist = spacing(event); if(newDist > 10f) { matrix.set(savedMatrix); float scale = newDist / oldDist; matrix.getValues(mvals); currentScale = mvals[0]; if(currentScale * scale <= minScale) { matrix.postScale(minScale/currentScale, minScale/currentScale, mid.x, mid.y); } else if(currentScale * scale >= maxScale) { matrix.postScale(maxScale/currentScale, maxScale/currentScale, mid.x, mid.y); } else { matrix.postScale(scale, scale, mid.x, mid.y); } matrix.getValues(mvals); curX = mvals[2]; curY = mvals[5]; currentScale = mvals[0]; } } break; } //Calculate the transformations and then invalidate invalidate(); return true; } 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); } 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); } public void setImageBitmap(Bitmap b) { if(b != null) { imgBitmap = b; containerWidth = getWidth(); containerHeight = getHeight(); int imgHeight = imgBitmap.getHeight(); int imgWidth = imgBitmap.getWidth(); float scale; int initX = 0; int initY = 0; matrix.reset(); if(defaultScale == ZoomableImageView.DEFAULT_SCALE_FIT_INSIDE) { if(imgWidth > containerWidth) { scale = (float)containerWidth / imgWidth; float newHeight = imgHeight * scale; initY = (containerHeight - (int)newHeight)/2; matrix.setScale(scale, scale); matrix.postTranslate(0, initY); } else { scale = (float)containerHeight / imgHeight; float newWidth = imgWidth * scale; initX = (containerWidth - (int)newWidth)/2; matrix.setScale(scale, scale); matrix.postTranslate(initX, 0); } curX = initX; curY = initY; currentScale = scale; minScale = scale; } else { if(imgWidth > containerWidth) { initX = 0; if(imgHeight > containerHeight) { initY = 0; } else { initY = (containerHeight - (int)imgHeight)/2; } matrix.postTranslate(0, initY); } else { initX = (containerWidth - (int)imgWidth)/2; if(imgHeight > containerHeight) { initY = 0; } else { initY = (containerHeight - (int)imgHeight)/2; } matrix.postTranslate(initX, 0); } curX = initX; curY = initY; currentScale = 1.0f; minScale = 1.0f; } invalidate(); } else { Log.d(TAG, "bitmap is null"); } } public Bitmap getPhotoBitmap() { return imgBitmap; } private Runnable mUpdateImagePositionTask = new Runnable() { public void run() { float[] mvals; if(Math.abs(targetX - curX) < 5 && Math.abs(targetY - curY) < 5) { isAnimating = false; mHandler.removeCallbacks(mUpdateImagePositionTask); mvals = new float[9]; matrix.getValues(mvals); currentScale = mvals[0]; curX = mvals[2]; curY = mvals[5]; //Set the image parameters and invalidate display float diffX = (targetX - curX); float diffY = (targetY - curY); matrix.postTranslate(diffX, diffY); } else { isAnimating = true; mvals = new float[9]; matrix.getValues(mvals); currentScale = mvals[0]; curX = mvals[2]; curY = mvals[5]; //Set the image parameters and invalidate display float diffX = (targetX - curX) * 0.3f; float diffY = (targetY - curY) * 0.3f; matrix.postTranslate(diffX, diffY); mHandler.postDelayed(this, 25); } invalidate(); } }; private Runnable mUpdateImageScale = new Runnable() { public void run() { float transitionalRatio = targetScale / currentScale; float dx; if(Math.abs(transitionalRatio - 1) > 0.05) { isAnimating = true; if(targetScale > currentScale) { dx = transitionalRatio - 1; scaleChange = 1 + dx * 0.2f; currentScale *= scaleChange; if(currentScale > targetScale) { currentScale = currentScale / scaleChange; scaleChange = 1; } } else { dx = 1 - transitionalRatio; scaleChange = 1 - dx * 0.5f; currentScale *= scaleChange; if(currentScale < targetScale) { currentScale = currentScale / scaleChange; scaleChange = 1; } } if(scaleChange != 1) { matrix.postScale(scaleChange, scaleChange, targetScaleX, targetScaleY); mHandler.postDelayed(mUpdateImageScale, 15); invalidate(); } else { isAnimating = false; scaleChange = 1; matrix.postScale(targetScale/currentScale, targetScale/currentScale, targetScaleX, targetScaleY); currentScale = targetScale; mHandler.removeCallbacks(mUpdateImageScale); invalidate(); checkImageConstraints(); } } else { isAnimating = false; scaleChange = 1; matrix.postScale(targetScale/currentScale, targetScale/currentScale, targetScaleX, targetScaleY); currentScale = targetScale; mHandler.removeCallbacks(mUpdateImageScale); invalidate(); checkImageConstraints(); } } }; /** Show an event in the LogCat view, for debugging */ private void dumpEvent(MotionEvent event) { String names[] = { "DOWN", "UP", "MOVE", "CANCEL", "OUTSIDE", "POINTER_DOWN", "POINTER_UP", "7?", "8?", "9?" }; StringBuilder sb = new StringBuilder(); int action = event.getAction(); int actionCode = action & MotionEvent.ACTION_MASK; sb.append("event ACTION_").append(names[actionCode]); if (actionCode == MotionEvent.ACTION_POINTER_DOWN || actionCode == MotionEvent.ACTION_POINTER_UP) { sb.append("(pid ").append(action >> MotionEvent.ACTION_POINTER_ID_SHIFT); sb.append(")"); } sb.append("["); for (int i = 0; i < event.getPointerCount(); i++) { sb.append("#").append(i); sb.append("(pid ").append(event.getPointerId(i)); sb.append(")=").append((int) event.getX(i)); sb.append(",").append((int) event.getY(i)); if (i + 1 < event.getPointerCount()) sb.append(";"); } sb.append("]"); } class MyGestureDetector extends SimpleOnGestureListener { @Override public boolean onDoubleTap(MotionEvent event) { if(isAnimating == true) { return true; } scaleChange = 1; isAnimating = true; targetScaleX = event.getX(); targetScaleY = event.getY(); if(Math.abs(currentScale - maxScale) > 0.1) { targetScale = maxScale; } else { targetScale = minScale; } targetRatio = targetScale / currentScale; mHandler.removeCallbacks(mUpdateImageScale); mHandler.post(mUpdateImageScale); return true; } @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { return super.onFling(e1, e2, velocityX, velocityY); } @Override public boolean onDown(MotionEvent e) { return false; } } }