Improvement which should hopefully help with bug #693607 - MupdfActivity crash when rotating the device.

When cancelling a render async task, we now wait for it to actually finish
before continuing. The benefit of this is that we should be able to guarantee
that its Bitmap becomes eligible for GC before we continue to create any
new bitmaps.

This should hopefully help with the OOM errors seen when rotating
the device and trying to create the new bitmaps.

To prevent the UI thread from being blocked for too long while we're waiting
for the async task to finish, we use a fz_cookie and set the 'abort' flag to
request the render be stopped as soon as possible.

1 files changed, 37 insertions, 6 deletions

diff --git a/platform/android/src/com/artifex/mupdfdemo/MuPDFCore.java b/platform/android/src/com/artifex/mupdfdemo/MuPDFCore.java
index ecdeccc7..ec35ef7c 100644
--- a/platform/android/src/com/artifex/mupdfdemo/MuPDFCore.java
+++ b/platform/android/src/com/artifex/mupdfdemo/MuPDFCore.java
@@ -33,12 +33,14 @@ public class MuPDFCore
 	private native void drawPage(Bitmap bitmap,
 			int pageW, int pageH,
 			int patchX, int patchY,
-			int patchW, int patchH);
+			int patchW, int patchH,
+			long cookiePtr);
 	private native void updatePageInternal(Bitmap bitmap,
 			int page,
 			int pageW, int pageH,
 			int patchX, int patchY,
-			int patchW, int patchH);
+			int patchW, int patchH,
+			long cookiePtr);
 	private native RectF[] searchPage(String text);
 	private native TextChar[][][][] text();
 	private native byte[] textAsHtml();
@@ -69,9 +71,36 @@ public class MuPDFCore
 	private native void destroying();
 	private native boolean hasChangesInternal();
 	private native void saveInternal();
+	private native long createCookie();
+	private native void destroyCookie(long cookie);
+	private native void abortCookie(long cookie);
 
 	public native boolean javascriptSupported();
 
+	public class Cookie
+	{
+		private final long cookiePtr;
+
+		public Cookie()
+		{
+			cookiePtr = createCookie();
+			if (cookiePtr == 0)
+				throw new OutOfMemoryError();
+		}
+
+		public void abort()
+		{
+			abortCookie(cookiePtr);
+		}
+
+		public void destroy()
+		{
+			// We could do this in finalize, but there's no guarantee that
+			// a finalize will occur before the muPDF context occurs.
+			destroyCookie(cookiePtr);
+		}
+	}
+
 	public MuPDFCore(Context context, String filename) throws Exception
 	{
 		globals = openFile(filename);
@@ -152,16 +181,18 @@ public class MuPDFCore
 	public synchronized void drawPage(Bitmap bm, int page,
 			int pageW, int pageH,
 			int patchX, int patchY,
-			int patchW, int patchH) {
+			int patchW, int patchH,
+			MuPDFCore.Cookie cookie) {
 		gotoPage(page);
-		drawPage(bm, pageW, pageH, patchX, patchY, patchW, patchH);
+		drawPage(bm, pageW, pageH, patchX, patchY, patchW, patchH, cookie.cookiePtr);
 	}
 
 	public synchronized void updatePage(Bitmap bm, int page,
 			int pageW, int pageH,
 			int patchX, int patchY,
-			int patchW, int patchH) {
-		updatePageInternal(bm, page, pageW, pageH, patchX, patchY, patchW, patchH);
+			int patchW, int patchH,
+			MuPDFCore.Cookie cookie) {
+		updatePageInternal(bm, page, pageW, pageH, patchX, patchY, patchW, patchH, cookie.cookiePtr);
 	}
 
 	public synchronized PassClickResult passClickEvent(int page, float x, float y) {