tdf#106893 android: Show whole doc when closing soft keyboard

When closing the software keyboard after typing,
a black area instead of the doc content was shown
in Android Viewer.
This looks related to the fact that a SurfaceView
is involved, s.a. [1] which suggests two potential
solutions to fix the issue, but none of them really
works well. (Setting a transparent background didn't
have any effect when I tried. Using
'android:windowSoftInputMode="adjustPan"' in
AndroidManifest.xml would work in general, but trigger
the  problem described in tdf#96789, namely the
software keyboard would be shown on top of the
document and the last part of the document would
not be visible with the software keyboard enabled
any more.)

Rather, make sure an 'LOEvent.SIZE_CHANGED' is
triggered when the software keyboard is enabled or
disabled, in which case 'LayerView#onLayout' is called
with a 'changed=true' parameter.
To avoid resetting zoom and position of the document
for this case, call the 'redraw' function with param
'false' when processing this type of event in
'LOKitThread#processEvent'
(s.a. Change-Id: I8ba6a7cd8d984ad99654e188e00144e1edf407ed,
"android: Don't reset zoom and position on refresh event"
that did a similar thing for 'LOEvent.REFRESH').

This adds a 'force' boolean parameter to
'GeckoLayerClient#sendResizeEventIfNecessary', which
interestingly had been there before commit

    43bbf53bba
    Date:   Tue Jan 27 13:01:53 2015 +0900

        android: remove unneded code from GeckoLayerClient

but I didn't further check whether it had been used
in any way that would have been useful for this
scenario back then.

Stackoverflow article [2] was quite helpful.

[1] https://stackoverflow.com/questions/2978290/androids-edittext-is-hidden-when-the-virtual-keyboard-is-shown-and-a-surfacevie
[2] https://stackoverflow.com/questions/52223095/how-to-detect-redraw-of-screen-has-completed-after-soft-keyboard-closes

Change-Id: If3fdd1335468fc50901fc6c1982c1463c7804309
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/115973
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

android/source/src/java/org/libreoffice/LOKitThread.java

@@ -295,7 +295,7 @@ class LOKitThread extends Thread {
                 closeDocument();
                 break;
             case LOEvent.SIZE_CHANGED:
-                redraw(true);
+                redraw(false);
                 break;
             case LOEvent.CHANGE_PART:
                 changePart(event.mPartIndex);

android/source/src/java/org/mozilla/gecko/gfx/GeckoLayerClient.java

@@ -80,7 +80,7 @@ public class GeckoLayerClient implements PanZoomTarget {
 
         mView.setLayerRenderer(mLayerRenderer);
 
-        sendResizeEventIfNecessary();
+        sendResizeEventIfNecessary(false);
         mView.requestRender();
     }
 
@@ -124,21 +124,23 @@ public class GeckoLayerClient implements PanZoomTarget {
      * to the layer client. That way, the layer client won't be tempted to call this, which might
      * result in an infinite loop.
      */
-    void setViewportSize(FloatSize size) {
+    void setViewportSize(FloatSize size, boolean forceResizeEvent) {
         mViewportMetrics = mViewportMetrics.setViewportSize(size.width, size.height);
-        sendResizeEventIfNecessary();
+        sendResizeEventIfNecessary(forceResizeEvent);
     }
 
     PanZoomController getPanZoomController() {
         return mPanZoomController;
     }
 
-    /* Informs Gecko that the screen size has changed. */
-    private void sendResizeEventIfNecessary() {
+    /* Informs Gecko that the screen size has changed.
+     * @param force: If true, a resize event will always be sent, otherwise
+     *               it is only sent if size has changed. */
+    private void sendResizeEventIfNecessary(boolean force) {
         DisplayMetrics metrics = mContext.getResources().getDisplayMetrics();
         IntSize newScreenSize = new IntSize(metrics.widthPixels, metrics.heightPixels);
 
-        if (mScreenSize.equals(newScreenSize)) {
+        if (!force && mScreenSize.equals(newScreenSize)) {
             return;
         }
 
@@ -233,7 +235,7 @@ public class GeckoLayerClient implements PanZoomTarget {
     }
 
     private void geometryChanged() {
-        sendResizeEventIfNecessary();
+        sendResizeEventIfNecessary(false);
         if (getRedrawHint()) {
             adjustViewport(null);
         }

android/source/src/java/org/mozilla/gecko/gfx/LayerView.java

@@ -302,7 +302,7 @@ public class LayerView extends FrameLayout {
     private void onSizeChanged(int width, int height) {
         mGLController.surfaceChanged(width, height);
 
-        mLayerClient.setViewportSize(new FloatSize(width, height));
+        mLayerClient.setViewportSize(new FloatSize(width, height), false);
 
         if (mListener != null) {
             mListener.surfaceChanged(width, height);
@@ -367,7 +367,7 @@ public class LayerView extends FrameLayout {
     protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
         super.onLayout(changed, left, top, right, bottom);
         if (changed) {
-            mLayerClient.setViewportSize(new FloatSize(right - left, bottom - top));
+            mLayerClient.setViewportSize(new FloatSize(right - left, bottom - top), true);
         }
     }