Imrove scrolling in the Android "Desktop" app

I got scrolling to respond to the JNI scroll method call.  (This is not yet
the gesture I want to implement (scroll by pixels), but at least it’s a
start.)

At first I tried to do some hacking in the C++ part, then found the problem
was in the Java parameters, which set the mouse whell delta too big.  When
passed the value 1 or -1 to the Y value of AppSupport.scroll(int x, int y),
the scrolling is reasonable.

Change-Id: Id8fa0ada1a035760b7b05bf21325d0e51ef28fdc

1 files changed, 7 insertions, 1 deletions

diff --git a/android/experimental/desktop/src/org/libreoffice/experimental/desktop/Desktop.java b/android/experimental/desktop/src/org/libreoffice/experimental/desktop/Desktop.java
index b24b0d70665e..b84333bd83cc 100644
--- a/android/experimental/desktop/src/org/libreoffice/experimental/desktop/Desktop.java
+++ b/android/experimental/desktop/src/org/libreoffice/experimental/desktop/Desktop.java
@@ -52,6 +52,12 @@ public class Desktop
 
     BootstrapContext bootstrapContext;
 
+    private static final Integer ZERO = 0;
+
+    private static int normalize(Number value) {
+        return ZERO.compareTo(-value.intValue());
+    }
+
     private void initBootstrapContext()
     {
         bootstrapContext = new BootstrapContext();
@@ -293,7 +299,7 @@ public class Desktop
             // the scroll must have ended.
 
             if (scrollInProgress) {
-                AppSupport.scroll((int) translateX, (int) translateY);
+                AppSupport.scroll(normalize(translateX), normalize(translateY));
                 translateX = translateY = 0;
                 scrollInProgress = false;
                 scrollJustEnded = true;