Android: a few improvements to the view handling

While scrolling, avoid some overheads to do with image scaling that
need updating only on a zoom-level change

Remove a pointless invalidate call.

Avoid calls to removeViewInLayout and removeAllViewsInLayout that
were being made in functions not called from onLayout

2 files changed, 16 insertions, 15 deletions

diff --git a/platform/android/src/com/artifex/mupdfdemo/PageView.java b/platform/android/src/com/artifex/mupdfdemo/PageView.java
index cc00e004..3e30d1e5 100644
--- a/platform/android/src/com/artifex/mupdfdemo/PageView.java
+++ b/platform/android/src/com/artifex/mupdfdemo/PageView.java
@@ -539,9 +539,11 @@ public abstract class PageView extends ViewGroup {
 		int h = bottom-top;
 
 		if (mEntire != null) {
-			mEntireMat.setScale(w/(float)mSize.x, h/(float)mSize.y);
-			mEntire.setImageMatrix(mEntireMat);
-			mEntire.invalidate();
+			if (mEntire.getWidth() != w || mEntire.getHeight() != h) {
+				mEntireMat.setScale(w/(float)mSize.x, h/(float)mSize.y);
+				mEntire.setImageMatrix(mEntireMat);
+				mEntire.invalidate();
+			}
 			mEntire.layout(0, 0, w, h);
 		}
 
@@ -631,7 +633,6 @@ public abstract class PageView extends ViewGroup {
 					// Calling requestLayout here doesn't lead to a later call to layout. No idea
 					// why, but apparently others have run into the problem.
 					mPatch.layout(mPatchArea.left, mPatchArea.top, mPatchArea.right, mPatchArea.bottom);
-					invalidate();
 				}
 			};
 
diff --git a/platform/android/src/com/artifex/mupdfdemo/ReaderView.java b/platform/android/src/com/artifex/mupdfdemo/ReaderView.java
index f779372b..fe183945 100644
--- a/platform/android/src/com/artifex/mupdfdemo/ReaderView.java
+++ b/platform/android/src/com/artifex/mupdfdemo/ReaderView.java
@@ -47,6 +47,7 @@ public class ReaderView
 	private int               mXScroll;    // Scroll amounts recorded from events.
 	private int               mYScroll;    // and then accounted for in onLayout
 	private boolean           mReflow = false;
+	private boolean           mReflowChanged = false;
 	private final GestureDetector
 				  mGestureDetector;
 	private final ScaleGestureDetector
@@ -289,19 +290,12 @@ public class ReaderView
 
 	public void refresh(boolean reflow) {
 		mReflow = reflow;
+		mReflowChanged = true;
+		mResetLayout = true;
 
 		mScale = 1.0f;
 		mXScroll = mYScroll = 0;
 
-		int numChildren = mChildViews.size();
-		for (int i = 0; i < numChildren; i++) {
-			View v = mChildViews.valueAt(i);
-			onNotInUse(v);
-			removeViewInLayout(v);
-		}
-		mChildViews.clear();
-		mViewCache.clear();
-
 		requestLayout();
 	}
 
@@ -590,6 +584,13 @@ public class ReaderView
 				removeViewInLayout(v);
 			}
 			mChildViews.clear();
+
+			// Don't reuse cached views if the adapter has changed
+			if (mReflowChanged) {
+				mReflowChanged = false;
+				mViewCache.clear();
+			}
+
 			// post to ensure generation of hq area
 			post(this);
 		}
@@ -668,8 +669,7 @@ public class ReaderView
 	@Override
 	public void setAdapter(Adapter adapter) {
 		mAdapter = adapter;
-		mChildViews.clear();
-		removeAllViewsInLayout();
+
 		requestLayout();
 	}