added centerOn, changed maxZoom method

ImageViewTouch/src/it/sephiroth/android/library/imagezoom/ImageViewTouch.java

@@ -16,7 +16,6 @@
 
 public class ImageViewTouch extends ImageViewTouchBase {
 
-	private static final float SCROLL_DELTA_THRESHOLD = 1.0f;
 	static final float MIN_ZOOM = 0.9f;
 	protected ScaleGestureDetector mScaleDetector;
 	protected GestureDetector mGestureDetector;
@@ -127,31 +126,7 @@ protected float onDoubleTapPost( float scale, float maxZoom ) {
 			return 1f;
 		}
 	}
-
-	/**
-	 * Determines whether this ImageViewTouch can be scrolled.
-	 * @param direction
-	 * 				- positive direction value means scroll from right to left, 
-	 * 				negative value means scroll from left to right
-	 * 
-	 * @return true if there is some more place to scroll, false - otherwise.
-	 */
-	public boolean canScroll(int direction) {
-		RectF bitmapRect = getBitmapRect();
-		updateRect(bitmapRect, mScrollRect);
-		Rect imageViewRect = new Rect();
-		getGlobalVisibleRect(imageViewRect);
-
-		if (bitmapRect.right >= imageViewRect.right) {
-			if (direction < 0) {
-				return Math.abs(bitmapRect.right - imageViewRect.right) > SCROLL_DELTA_THRESHOLD;
-			}
-		}
-
-		double bitmapScrollRectDelta = Math.abs(bitmapRect.left - mScrollRect.left);
-		return bitmapScrollRectDelta > SCROLL_DELTA_THRESHOLD;
-	}
-
+
 	public class GestureListener extends GestureDetector.SimpleOnGestureListener {
 
 		@Override

ImageViewTouch/src/it/sephiroth/android/library/imagezoom/ImageViewTouchBase.java

@@ -226,7 +226,8 @@ protected float maxZoom() {
 
 		float fw = (float) drawable.getIntrinsicWidth() / (float) mThisWidth;
 		float fh = (float) drawable.getIntrinsicHeight() / (float) mThisHeight;
-		float max = Math.max( fw, fh ) * 4;
+
+		float max = (1.0f / Math.min( fw, fh )) * 4;
 		return max;
 	}
 
@@ -403,6 +404,33 @@ protected void zoomTo( float scale, float centerX, float centerY ) {
 
 	protected void onZoom( float scale ) {}
 
+	/**
+	 * Center on a specific coordinate in the image.
+	 * 
+	 * This method uses image-based coordinates, with 0,0 at the top left of the image.  It is scale agnostic.
+	 * 
+	 */
+	public void centerOn( float x, float y ) {
+        Drawable d = getDrawable();
+        if (d == null) {
+            return; //nothing to do
+        }
+	    //get the bitmap rect, which represents the rectangle of the view at the specified scale
+	    //NOTE: this currently has no relation to the actual bitmap...we will provide that relation in this method
+        RectF rect = getBitmapRect();
+        float screenMidX = getWidth() / 2;
+        float screenMidY = getHeight() / 2;
+        //determine the centerX and centerY of the image on screen (these coordinates are scaled image coordinates)
+        float viewCenterX  = -(rect.left - screenMidX);
+        float viewCenterY  = -(rect.top  - screenMidY);
+
+        //NOTE: postTranslate expects - numbers to pull the image right and + to pull it left
+        float xp = viewCenterX - (x / d.getIntrinsicWidth())  * (rect.right - rect.left);
+        //NOTE: postTranslate expects - numbers to pull the image down, and + to pull it up
+        float yp = viewCenterY - (y / d.getIntrinsicHeight()) * (rect.bottom - rect.top);
+	    postTranslate(xp, yp);
+	}
+
 	public void scrollBy( float x, float y ) {
 		panBy( x, y );
 	}
@@ -462,21 +490,26 @@ protected void zoomTo( float scale, final float centerX, final float centerY, fi
 		final long startTime = System.currentTimeMillis();
 		final float incrementPerMs = ( scale - getScale() ) / durationMs;
 		final float oldScale = getScale();
-		mHandler.post( new Runnable() {
-
-			@Override
-			public void run() {
-				long now = System.currentTimeMillis();
-				float currentMs = Math.min( durationMs, now - startTime );
-				float target = oldScale + ( incrementPerMs * currentMs );
-				zoomTo( target, centerX, centerY );
-				if ( currentMs < durationMs ) {
-					mHandler.post( this );
-				} else {
-					// if ( getScale() < 1f ) {}
-				}
-			}
-		} );
+		if (durationMs == 0) {
+		    //special case for instantaneous zoom
+		    zoomTo(scale, centerX, centerY);
+		} else {
+    		mHandler.post( new Runnable() {
+
+    			@Override
+    			public void run() {
+    				long now = System.currentTimeMillis();
+    				float currentMs = Math.min( durationMs, now - startTime );
+    				float target = oldScale + ( incrementPerMs * currentMs );
+    				zoomTo( target, centerX, centerY );
+    				if ( currentMs < durationMs ) {
+    					mHandler.post( this );
+    				} else {
+    					// if ( getScale() < 1f ) {}
+    				}
+    			}
+    		} );
+		}
 	}
 
 	@Override