Add scroll wheel support to TextView.

Change-Id: I6e4258c50b0d754dccf07266ff4b2abcbccd733a

3 files changed, 317 insertions, 145 deletions

diff --git a/core/java/android/text/method/BaseMovementMethod.java b/core/java/android/text/method/BaseMovementMethod.java
index 2be18d6..94c6ed0 100644
--- a/core/java/android/text/method/BaseMovementMethod.java
+++ b/core/java/android/text/method/BaseMovementMethod.java
@@ -18,6 +18,7 @@ package android.text.method;
 
 import android.text.Layout;
 import android.text.Spannable;
+import android.view.InputDevice;
 import android.view.KeyEvent;
 import android.view.MotionEvent;
 import android.widget.TextView;
@@ -88,6 +89,39 @@ public class BaseMovementMethod implements MovementMethod {
         return false;
     }
 
+    @Override
+    public boolean onGenericMotionEvent(TextView widget, Spannable text, MotionEvent event) {
+        if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) {
+            switch (event.getAction()) {
+                case MotionEvent.ACTION_SCROLL: {
+                    final float vscroll;
+                    final float hscroll;
+                    if ((event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0) {
+                        vscroll = 0;
+                        hscroll = event.getAxisValue(MotionEvent.AXIS_VSCROLL);
+                    } else {
+                        vscroll = -event.getAxisValue(MotionEvent.AXIS_VSCROLL);
+                        hscroll = event.getAxisValue(MotionEvent.AXIS_HSCROLL);
+                    }
+
+                    boolean handled = false;
+                    if (hscroll < 0) {
+                        handled |= scrollLeft(widget, text, (int)Math.ceil(-hscroll));
+                    } else if (hscroll > 0) {
+                        handled |= scrollRight(widget, text, (int)Math.ceil(hscroll));
+                    }
+                    if (vscroll < 0) {
+                        handled |= scrollUp(widget, text, (int)Math.ceil(-vscroll));
+                    } else if (vscroll > 0) {
+                        handled |= scrollDown(widget, text, (int)Math.ceil(vscroll));
+                    }
+                    return handled;
+                }
+            }
+        }
+        return false;
+    }
+
     /**
      * Gets the meta state used for movement using the modifiers tracked by the text
      * buffer as well as those present in the key event.
@@ -342,4 +376,276 @@ public class BaseMovementMethod implements MovementMethod {
     protected boolean end(TextView widget, Spannable buffer) {
         return false;
     }
+
+    private int getTopLine(TextView widget) {
+        return widget.getLayout().getLineForVertical(widget.getScrollY());
+    }
+
+    private int getBottomLine(TextView widget) {
+        return widget.getLayout().getLineForVertical(widget.getScrollY() + getInnerHeight(widget));
+    }
+
+    private int getInnerWidth(TextView widget) {
+        return widget.getWidth() - widget.getTotalPaddingLeft() - widget.getTotalPaddingRight();
+    }
+
+    private int getInnerHeight(TextView widget) {
+        return widget.getHeight() - widget.getTotalPaddingTop() - widget.getTotalPaddingBottom();
+    }
+
+    private int getCharacterWidth(TextView widget) {
+        return (int) Math.ceil(widget.getPaint().getFontSpacing());
+    }
+
+    private int getScrollBoundsLeft(TextView widget) {
+        final Layout layout = widget.getLayout();
+        final int topLine = getTopLine(widget);
+        final int bottomLine = getBottomLine(widget);
+        if (topLine > bottomLine) {
+            return 0;
+        }
+        int left = Integer.MAX_VALUE;
+        for (int line = topLine; line <= bottomLine; line++) {
+            final int lineLeft = (int) Math.floor(layout.getLineLeft(line));
+            if (lineLeft < left) {
+                left = lineLeft;
+            }
+        }
+        return left;
+    }
+
+    private int getScrollBoundsRight(TextView widget) {
+        final Layout layout = widget.getLayout();
+        final int topLine = getTopLine(widget);
+        final int bottomLine = getBottomLine(widget);
+        if (topLine > bottomLine) {
+            return 0;
+        }
+        int right = Integer.MIN_VALUE;
+        for (int line = topLine; line <= bottomLine; line++) {
+            final int lineRight = (int) Math.ceil(layout.getLineRight(line));
+            if (lineRight > right) {
+                right = lineRight;
+            }
+        }
+        return right;
+    }
+
+    /**
+     * Performs a scroll left action.
+     * Scrolls left by the specified number of characters.
+     *
+     * @param widget The text view.
+     * @param buffer The text buffer.
+     * @param amount The number of characters to scroll by.  Must be at least 1.
+     * @return True if the event was handled.
+     * @hide
+     */
+    protected boolean scrollLeft(TextView widget, Spannable buffer, int amount) {
+        final int minScrollX = getScrollBoundsLeft(widget);
+        int scrollX = widget.getScrollX();
+        if (scrollX > minScrollX) {
+            scrollX = Math.max(scrollX - getCharacterWidth(widget) * amount, minScrollX);
+            widget.scrollTo(scrollX, widget.getScrollY());
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Performs a scroll right action.
+     * Scrolls right by the specified number of characters.
+     *
+     * @param widget The text view.
+     * @param buffer The text buffer.
+     * @param amount The number of characters to scroll by.  Must be at least 1.
+     * @return True if the event was handled.
+     * @hide
+     */
+    protected boolean scrollRight(TextView widget, Spannable buffer, int amount) {
+        final int maxScrollX = getScrollBoundsRight(widget) - getInnerWidth(widget);
+        int scrollX = widget.getScrollX();
+        if (scrollX < maxScrollX) {
+            scrollX = Math.min(scrollX + getCharacterWidth(widget) * amount, maxScrollX);
+            widget.scrollTo(scrollX, widget.getScrollY());
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Performs a scroll up action.
+     * Scrolls up by the specified number of lines.
+     *
+     * @param widget The text view.
+     * @param buffer The text buffer.
+     * @param amount The number of lines to scroll by.  Must be at least 1.
+     * @return True if the event was handled.
+     * @hide
+     */
+    protected boolean scrollUp(TextView widget, Spannable buffer, int amount) {
+        final Layout layout = widget.getLayout();
+        final int top = widget.getScrollY();
+        int topLine = layout.getLineForVertical(top);
+        if (layout.getLineTop(topLine) == top) {
+            // If the top line is partially visible, bring it all the way
+            // into view; otherwise, bring the previous line into view.
+            topLine -= 1;
+        }
+        if (topLine >= 0) {
+            topLine = Math.max(topLine - amount + 1, 0);
+            Touch.scrollTo(widget, layout, widget.getScrollX(), layout.getLineTop(topLine));
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Performs a scroll down action.
+     * Scrolls down by the specified number of lines.
+     *
+     * @param widget The text view.
+     * @param buffer The text buffer.
+     * @param amount The number of lines to scroll by.  Must be at least 1.
+     * @return True if the event was handled.
+     * @hide
+     */
+    protected boolean scrollDown(TextView widget, Spannable buffer, int amount) {
+        final Layout layout = widget.getLayout();
+        final int innerHeight = getInnerHeight(widget);
+        final int bottom = widget.getScrollY() + innerHeight;
+        int bottomLine = layout.getLineForVertical(bottom);
+        if (layout.getLineTop(bottomLine + 1) < bottom + 1) {
+            // Less than a pixel of this line is out of view,
+            // so we must have tried to make it entirely in view
+            // and now want the next line to be in view instead.
+            bottomLine += 1;
+        }
+        final int limit = layout.getLineCount() - 1;
+        if (bottomLine <= limit) {
+            bottomLine = Math.min(bottomLine + amount - 1, limit);
+            Touch.scrollTo(widget, layout, widget.getScrollX(),
+                    layout.getLineTop(bottomLine + 1) - innerHeight);
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Performs a scroll page up action.
+     * Scrolls up by one page.
+     *
+     * @param widget The text view.
+     * @param buffer The text buffer.
+     * @return True if the event was handled.
+     * @hide
+     */
+    protected boolean scrollPageUp(TextView widget, Spannable buffer) {
+        final Layout layout = widget.getLayout();
+        final int top = widget.getScrollY() - getInnerHeight(widget);
+        int topLine = layout.getLineForVertical(top);
+        if (topLine >= 0) {
+            Touch.scrollTo(widget, layout, widget.getScrollX(), layout.getLineTop(topLine));
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Performs a scroll page up action.
+     * Scrolls down by one page.
+     *
+     * @param widget The text view.
+     * @param buffer The text buffer.
+     * @return True if the event was handled.
+     * @hide
+     */
+    protected boolean scrollPageDown(TextView widget, Spannable buffer) {
+        final Layout layout = widget.getLayout();
+        final int innerHeight = getInnerHeight(widget);
+        final int bottom = widget.getScrollY() + innerHeight + innerHeight;
+        int bottomLine = layout.getLineForVertical(bottom);
+        if (bottomLine <= layout.getLineCount() - 1) {
+            Touch.scrollTo(widget, layout, widget.getScrollX(),
+                    layout.getLineTop(bottomLine + 1) - innerHeight);
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Performs a scroll to top action.
+     * Scrolls to the top of the document.
+     *
+     * @param widget The text view.
+     * @param buffer The text buffer.
+     * @return True if the event was handled.
+     * @hide
+     */
+    protected boolean scrollTop(TextView widget, Spannable buffer) {
+        final Layout layout = widget.getLayout();
+        if (getTopLine(widget) >= 0) {
+            Touch.scrollTo(widget, layout, widget.getScrollX(), layout.getLineTop(0));
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Performs a scroll to bottom action.
+     * Scrolls to the bottom of the document.
+     *
+     * @param widget The text view.
+     * @param buffer The text buffer.
+     * @return True if the event was handled.
+     * @hide
+     */
+    protected boolean scrollBottom(TextView widget, Spannable buffer) {
+        final Layout layout = widget.getLayout();
+        final int lineCount = layout.getLineCount();
+        if (getBottomLine(widget) <= lineCount - 1) {
+            Touch.scrollTo(widget, layout, widget.getScrollX(),
+                    layout.getLineTop(lineCount) - getInnerHeight(widget));
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Performs a scroll to line start action.
+     * Scrolls to the start of the line.
+     *
+     * @param widget The text view.
+     * @param buffer The text buffer.
+     * @return True if the event was handled.
+     * @hide
+     */
+    protected boolean scrollLineStart(TextView widget, Spannable buffer) {
+        final int minScrollX = getScrollBoundsLeft(widget);
+        int scrollX = widget.getScrollX();
+        if (scrollX > minScrollX) {
+            widget.scrollTo(minScrollX, widget.getScrollY());
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Performs a scroll to line end action.
+     * Scrolls to the end of the line.
+     *
+     * @param widget The text view.
+     * @param buffer The text buffer.
+     * @return True if the event was handled.
+     * @hide
+     */
+    protected boolean scrollLineEnd(TextView widget, Spannable buffer) {
+        final int maxScrollX = getScrollBoundsRight(widget) - getInnerWidth(widget);
+        int scrollX = widget.getScrollX();
+        if (scrollX < maxScrollX) {
+            widget.scrollTo(maxScrollX, widget.getScrollY());
+            return true;
+        }
+        return false;
+    }
 }
diff --git a/core/java/android/text/method/MovementMethod.java b/core/java/android/text/method/MovementMethod.java
index 9167676..01979fd 100644
--- a/core/java/android/text/method/MovementMethod.java
+++ b/core/java/android/text/method/MovementMethod.java
@@ -47,6 +47,7 @@ public interface MovementMethod {
     public void onTakeFocus(TextView widget, Spannable text, int direction);
     public boolean onTrackballEvent(TextView widget, Spannable text, MotionEvent event);
     public boolean onTouchEvent(TextView widget, Spannable text, MotionEvent event);
+    public boolean onGenericMotionEvent(TextView widget, Spannable text, MotionEvent event);
 
     /**
      * Returns true if this movement method allows arbitrary selection
diff --git a/core/java/android/text/method/ScrollingMovementMethod.java b/core/java/android/text/method/ScrollingMovementMethod.java
index 194ecc1..b9f5d5f 100644
--- a/core/java/android/text/method/ScrollingMovementMethod.java
+++ b/core/java/android/text/method/ScrollingMovementMethod.java
@@ -25,189 +25,54 @@ import android.view.View;
  * A movement method that interprets movement keys by scrolling the text buffer.
  */
 public class ScrollingMovementMethod extends BaseMovementMethod implements MovementMethod {
-    private int getTopLine(TextView widget) {
-        return widget.getLayout().getLineForVertical(widget.getScrollY());
-    }
-
-    private int getBottomLine(TextView widget) {
-        return widget.getLayout().getLineForVertical(widget.getScrollY() + getInnerHeight(widget));
-    }
-
-    private int getInnerWidth(TextView widget) {
-        return widget.getWidth() - widget.getTotalPaddingLeft() - widget.getTotalPaddingRight();
-    }
-
-    private int getInnerHeight(TextView widget) {
-        return widget.getHeight() - widget.getTotalPaddingTop() - widget.getTotalPaddingBottom();
-    }
-
-    private int getCharacterWidth(TextView widget) {
-        return (int) Math.ceil(widget.getPaint().getFontSpacing());
-    }
-
-    private int getScrollBoundsLeft(TextView widget) {
-        final Layout layout = widget.getLayout();
-        final int topLine = getTopLine(widget);
-        final int bottomLine = getBottomLine(widget);
-        if (topLine > bottomLine) {
-            return 0;
-        }
-        int left = Integer.MAX_VALUE;
-        for (int line = topLine; line <= bottomLine; line++) {
-            final int lineLeft = (int) Math.floor(layout.getLineLeft(line));
-            if (lineLeft < left) {
-                left = lineLeft;
-            }
-        }
-        return left;
-    }
-
-    private int getScrollBoundsRight(TextView widget) {
-        final Layout layout = widget.getLayout();
-        final int topLine = getTopLine(widget);
-        final int bottomLine = getBottomLine(widget);
-        if (topLine > bottomLine) {
-            return 0;
-        }
-        int right = Integer.MIN_VALUE;
-        for (int line = topLine; line <= bottomLine; line++) {
-            final int lineRight = (int) Math.ceil(layout.getLineRight(line));
-            if (lineRight > right) {
-                right = lineRight;
-            }
-        }
-        return right;
-    }
-
     @Override
     protected boolean left(TextView widget, Spannable buffer) {
-        final int minScrollX = getScrollBoundsLeft(widget);
-        int scrollX = widget.getScrollX();
-        if (scrollX > minScrollX) {
-            scrollX = Math.max(scrollX - getCharacterWidth(widget), minScrollX);
-            widget.scrollTo(scrollX, widget.getScrollY());
-            return true;
-        }
-        return false;
+        return scrollLeft(widget, buffer, 1);
     }
 
     @Override
     protected boolean right(TextView widget, Spannable buffer) {
-        final int maxScrollX = getScrollBoundsRight(widget) - getInnerWidth(widget);
-        int scrollX = widget.getScrollX();
-        if (scrollX < maxScrollX) {
-            scrollX = Math.min(scrollX + getCharacterWidth(widget), maxScrollX);
-            widget.scrollTo(scrollX, widget.getScrollY());
-            return true;
-        }
-        return false;
+        return scrollRight(widget, buffer, 1);
     }
 
     @Override
     protected boolean up(TextView widget, Spannable buffer) {
-        final Layout layout = widget.getLayout();
-        final int top = widget.getScrollY();
-        int topLine = layout.getLineForVertical(top);
-        if (layout.getLineTop(topLine) == top) {
-            // If the top line is partially visible, bring it all the way
-            // into view; otherwise, bring the previous line into view.
-            topLine -= 1;
-        }
-        if (topLine >= 0) {
-            Touch.scrollTo(widget, layout, widget.getScrollX(), layout.getLineTop(topLine));
-            return true;
-        }
-        return false;
+        return scrollUp(widget, buffer, 1);
     }
 
     @Override
     protected boolean down(TextView widget, Spannable buffer) {
-        final Layout layout = widget.getLayout();
-        final int innerHeight = getInnerHeight(widget);
-        final int bottom = widget.getScrollY() + innerHeight;
-        int bottomLine = layout.getLineForVertical(bottom);
-        if (layout.getLineTop(bottomLine + 1) < bottom + 1) {
-            // Less than a pixel of this line is out of view,
-            // so we must have tried to make it entirely in view
-            // and now want the next line to be in view instead.
-            bottomLine += 1;
-        }
-        if (bottomLine <= layout.getLineCount() - 1) {
-            Touch.scrollTo(widget, layout, widget.getScrollX(),
-                    layout.getLineTop(bottomLine + 1) - innerHeight);
-            return true;
-        }
-        return false;
+        return scrollDown(widget, buffer, 1);
     }
 
     @Override
     protected boolean pageUp(TextView widget, Spannable buffer) {
-        final Layout layout = widget.getLayout();
-        final int top = widget.getScrollY() - getInnerHeight(widget);
-        int topLine = layout.getLineForVertical(top);
-        if (topLine >= 0) {
-            Touch.scrollTo(widget, layout, widget.getScrollX(), layout.getLineTop(topLine));
-            return true;
-        }
-        return false;
+        return scrollPageUp(widget, buffer);
     }
 
     @Override
     protected boolean pageDown(TextView widget, Spannable buffer) {
-        final Layout layout = widget.getLayout();
-        final int innerHeight = getInnerHeight(widget);
-        final int bottom = widget.getScrollY() + innerHeight + innerHeight;
-        int bottomLine = layout.getLineForVertical(bottom);
-        if (bottomLine <= layout.getLineCount() - 1) {
-            Touch.scrollTo(widget, layout, widget.getScrollX(),
-                    layout.getLineTop(bottomLine + 1) - innerHeight);
-            return true;
-        }
-        return false;
+        return scrollPageDown(widget, buffer);
     }
 
     @Override
     protected boolean top(TextView widget, Spannable buffer) {
-        final Layout layout = widget.getLayout();
-        if (getTopLine(widget) >= 0) {
-            Touch.scrollTo(widget, layout, widget.getScrollX(), layout.getLineTop(0));
-            return true;
-        }
-        return false;
+        return scrollTop(widget, buffer);
     }
 
     @Override
     protected boolean bottom(TextView widget, Spannable buffer) {
-        final Layout layout = widget.getLayout();
-        final int lineCount = layout.getLineCount();
-        if (getBottomLine(widget) <= lineCount - 1) {
-            Touch.scrollTo(widget, layout, widget.getScrollX(),
-                    layout.getLineTop(lineCount) - getInnerHeight(widget));
-            return true;
-        }
-        return false;
+        return scrollBottom(widget, buffer);
     }
 
     @Override
     protected boolean lineStart(TextView widget, Spannable buffer) {
-        final int minScrollX = getScrollBoundsLeft(widget);
-        int scrollX = widget.getScrollX();
-        if (scrollX > minScrollX) {
-            widget.scrollTo(minScrollX, widget.getScrollY());
-            return true;
-        }
-        return false;
+        return scrollLineStart(widget, buffer);
     }
 
     @Override
     protected boolean lineEnd(TextView widget, Spannable buffer) {
-        final int maxScrollX = getScrollBoundsRight(widget) - getInnerWidth(widget);
-        int scrollX = widget.getScrollX();
-        if (scrollX < maxScrollX) {
-            widget.scrollTo(maxScrollX, widget.getScrollY());
-            return true;
-        }
-        return false;
+        return scrollLineEnd(widget, buffer);
     }
 
     @Override