Fix for bug 6954231 text wraps on second line and is fused...

When breaking a line, the paragraphs below the new line break were still
being drawn in their old location. This only happened when the height
was fill_parent, otherwise the height change would force a relayout,
which in turn would do a full invalidation.

This patch checks for changes to the layout height (not just the widget
height, which won't change when it's fill_parent), and invalidates.

Change-Id: I64adb9f5eae0479c1c9c8d37c10c2c27a6f582a8

Author: raphlinus

core/java/android/widget/Editor.java

@@ -122,6 +122,7 @@ public class Editor {
     InputMethodState mInputMethodState;
 
     DisplayList[] mTextDisplayLists;
+    int mLastLayoutHeight;
 
     boolean mFrozenWithFocus;
     boolean mSelectionMoved;
@@ -1258,6 +1259,16 @@ private void drawHardwareAccelerated(Canvas canvas, Layout layout, Path highligh
                 mTextDisplayLists = new DisplayList[ArrayUtils.idealObjectArraySize(0)];
             }
 
+            // If the height of the layout changes (usually when inserting or deleting a line,
+            // but could be changes within a span), invalidate everything. We could optimize
+            // more aggressively (for example, adding offsets to blocks) but it would be more
+            // complex and we would only get the benefit in some cases.
+            int layoutHeight = layout.getHeight();
+            if (mLastLayoutHeight != layoutHeight) {
+                invalidateTextDisplayList();
+                mLastLayoutHeight = layoutHeight;
+            }
+
             DynamicLayout dynamicLayout = (DynamicLayout) layout;
             int[] blockEndLines = dynamicLayout.getBlockEndLines();
             int[] blockIndices = dynamicLayout.getBlockIndices();