Android example - fix to maintain vertical center when zooming.

1 files changed, 6 insertions, 1 deletions

diff --git a/platform/android/example/mupdf/src/main/java/com/artifex/mupdf/android/DocViewBase.java b/platform/android/example/mupdf/src/main/java/com/artifex/mupdf/android/DocViewBase.java
index 5ecc75d8..10cf78ca 100755
--- a/platform/android/example/mupdf/src/main/java/com/artifex/mupdf/android/DocViewBase.java
+++ b/platform/android/example/mupdf/src/main/java/com/artifex/mupdf/android/DocViewBase.java
@@ -477,9 +477,14 @@ public class DocViewBase
 			mScale *= ratio;
 			scaleChildren();
 
-			//  scroll so the left edged is flush to the viewport.
+			//  scroll horizontally so the left edge is flush with the viewport.
 			mXScroll += getScrollX();
 
+			//  scroll vertically to maintain the center.
+			int oldy = mViewport.centerY() - mLastBlockRect.top;
+			int newy = (int) ((float) oldy * ratio);
+			mYScroll -= (newy-oldy);
+
 			requestLayout();
 		}