下面列出了android.view.View#FOCUS_FORWARD 实例代码，或者点击链接到github查看源代码，也可以在右侧发表评论。
/**
* When looking for focus in children of a scroll view, need to be a little
* more careful not to give focus to something that is scrolled off screen.
* <p/>
* This is more expensive than the default {@link android.view.ViewGroup}
* implementation, otherwise this behavior might have been made the default.
*/
@Override
protected boolean onRequestFocusInDescendants(int direction, Rect previouslyFocusedRect) {
// convert from forward / backward notation to up / down / left / right
// (ugh).
if (direction == View.FOCUS_FORWARD) {
direction = View.FOCUS_DOWN;
} else if (direction == View.FOCUS_BACKWARD) {
direction = View.FOCUS_UP;
}
final View nextFocus = previouslyFocusedRect == null ?
FocusFinder.getInstance().findNextFocus(this, null, direction) :
FocusFinder.getInstance().findNextFocusFromRect(this,
previouslyFocusedRect, direction);
if (nextFocus == null) {
return false;
}
return nextFocus.requestFocus(direction, previouslyFocusedRect);
}
/**
* When looking for focus in children of a scroll view, need to be a little
* more careful not to give focus to something that is scrolled off screen.
* <p/>
* This is more expensive than the default {@link android.view.ViewGroup}
* implementation, otherwise this behavior might have been made the default.
*/
@Override
protected boolean onRequestFocusInDescendants(int direction, Rect previouslyFocusedRect) {
// convert from forward / backward notation to up / down / left / right
// (ugh).
if (direction == View.FOCUS_FORWARD) {
direction = View.FOCUS_DOWN;
} else if (direction == View.FOCUS_BACKWARD) {
direction = View.FOCUS_UP;
}
final View nextFocus = previouslyFocusedRect == null ?
FocusFinder.getInstance().findNextFocus(this, null, direction) :
FocusFinder.getInstance().findNextFocusFromRect(this,
previouslyFocusedRect, direction);
if (nextFocus == null) {
return false;
}
return nextFocus.requestFocus(direction, previouslyFocusedRect);
}
/**
* When looking for focus in children of a scroll view, need to be a little
* more careful not to give focus to something that is scrolled off screen.
*
* This is more expensive than the default {@link ViewGroup}
* implementation, otherwise this behavior might have been made the default.
*/
@Override
protected boolean onRequestFocusInDescendants(int direction, Rect previouslyFocusedRect) {
// convert from forward / backward notation to up / down / left / right
// (ugh).
if (direction == View.FOCUS_FORWARD) {
direction = View.FOCUS_DOWN;
} else if (direction == View.FOCUS_BACKWARD) {
direction = View.FOCUS_UP;
}
final View nextFocus = previouslyFocusedRect == null ?
FocusFinder.getInstance().findNextFocus(this, null, direction) :
FocusFinder.getInstance().findNextFocusFromRect(this,
previouslyFocusedRect, direction);
if (nextFocus == null) {
return false;
}
return nextFocus.requestFocus(direction, previouslyFocusedRect);
}
private void enforceValidFocusDirection(int direction) {
switch (direction) {
case View.FOCUS_DOWN:
case View.FOCUS_UP:
case View.FOCUS_LEFT:
case View.FOCUS_RIGHT:
case View.FOCUS_FORWARD:
case View.FOCUS_BACKWARD:
return;
default:
throw new IllegalArgumentException("Unknown direction: " + direction);
}
}
private boolean gridOnRequestFocusInDescendantsUnaligned(RecyclerView recyclerView,
int direction, Rect previouslyFocusedRect) {
// focus to view not overlapping padding area to avoid scrolling in gaining focus
int index;
int increment;
int end;
int count = getChildCount();
if ((direction & View.FOCUS_FORWARD) != 0) {
index = 0;
increment = 1;
end = count;
} else {
index = count - 1;
increment = -1;
end = -1;
}
int left = getPaddingLow();
int right = getClientSize() + left;
for (int i = index; i != end; i += increment) {
View child = getChildAt(i);
if (child.getVisibility() == View.VISIBLE) {
if (getViewMin(child) >= left && getViewMax(child) <= right) {
if (child.requestFocus(direction, previouslyFocusedRect)) {
return true;
}
}
}
}
return false;
}
/**
* When looking for focus in children of a scroll view, need to be a little
* more careful not to give focus to something that is scrolled off screen.
*
* This is more expensive than the default {@link android.view.ViewGroup}
* implementation, otherwise this behavior might have been made the default.
*/
@Override
protected boolean onRequestFocusInDescendants(int direction,
Rect previouslyFocusedRect) {
// convert from forward / backward notation to up / down / left / right
// (ugh).
if (direction == View.FOCUS_FORWARD) {
direction = View.FOCUS_RIGHT;
} else if (direction == View.FOCUS_BACKWARD) {
direction = View.FOCUS_LEFT;
}
final View nextFocus = previouslyFocusedRect == null ?
FocusFinder.getInstance().findNextFocus(this, null, direction) :
FocusFinder.getInstance().findNextFocusFromRect(this,
previouslyFocusedRect, direction);
if (nextFocus == null) {
return false;
}
if (isOffScreen(nextFocus)) {
return false;
}
return nextFocus.requestFocus(direction, previouslyFocusedRect);
}
/**
* When looking for focus in children of a scroll view, need to be a little
* more careful not to give focus to something that is scrolled off screen.
*
* This is more expensive than the default {@link android.view.ViewGroup}
* implementation, otherwise this behavior might have been made the default.
*/
@Override
protected boolean onRequestFocusInDescendants(int direction,
Rect previouslyFocusedRect) {
// convert from forward / backward notation to up / down / left / right
// (ugh).
if (direction == View.FOCUS_FORWARD) {
direction = View.FOCUS_DOWN;
} else if (direction == View.FOCUS_BACKWARD) {
direction = View.FOCUS_UP;
}
final View nextFocus = previouslyFocusedRect == null ?
FocusFinder.getInstance().findNextFocus(this, null, direction) :
FocusFinder.getInstance().findNextFocusFromRect(this,
previouslyFocusedRect, direction);
if (nextFocus == null) {
return false;
}
if (isOffScreen(nextFocus)) {
return false;
}
return nextFocus.requestFocus(direction, previouslyFocusedRect);
}
/**
* Converts a focusDirection to orientation.
*
* @param focusDirection One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN},
* {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT},
* {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD}
* or 0 for not applicable
* @return {@link LayoutState#LAYOUT_START} or {@link LayoutState#LAYOUT_END} if focus direction
* is applicable to current state, {@link LayoutState#INVALID_LAYOUT} otherwise.
*/
int convertFocusDirectionToLayoutDirection(int focusDirection) {
switch (focusDirection) {
case View.FOCUS_BACKWARD:
if (mOrientation == VERTICAL) {
return LayoutState.LAYOUT_START;
} else if (isLayoutRTL()) {
return LayoutState.LAYOUT_END;
} else {
return LayoutState.LAYOUT_START;
}
case View.FOCUS_FORWARD:
if (mOrientation == VERTICAL) {
return LayoutState.LAYOUT_END;
} else if (isLayoutRTL()) {
return LayoutState.LAYOUT_START;
} else {
return LayoutState.LAYOUT_END;
}
case View.FOCUS_UP:
return mOrientation == VERTICAL ? LayoutState.LAYOUT_START
: LayoutState.INVALID_LAYOUT;
case View.FOCUS_DOWN:
return mOrientation == VERTICAL ? LayoutState.LAYOUT_END
: LayoutState.INVALID_LAYOUT;
case View.FOCUS_LEFT:
return mOrientation == HORIZONTAL ? LayoutState.LAYOUT_START
: LayoutState.INVALID_LAYOUT;
case View.FOCUS_RIGHT:
return mOrientation == HORIZONTAL ? LayoutState.LAYOUT_END
: LayoutState.INVALID_LAYOUT;
default:
if (DEBUG) {
Log.d(TAG, "Unknown focus request:" + focusDirection);
}
return LayoutState.INVALID_LAYOUT;
}
}
/**
* Converts a focusDirection to orientation.
*
* @param focusDirection One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN},
* {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT},
* {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD}
* or 0 for not applicable
* @return {@link RenderState#LAYOUT_START} or {@link RenderState#LAYOUT_END} if focus direction
* is applicable to current state, {@link RenderState#INVALID_LAYOUT} otherwise.
*/
private int convertFocusDirectionToLayoutDirection(int focusDirection) {
switch (focusDirection) {
case View.FOCUS_BACKWARD:
return RenderState.LAYOUT_START;
case View.FOCUS_FORWARD:
return RenderState.LAYOUT_END;
case View.FOCUS_UP:
return mOrientation == VERTICAL ? RenderState.LAYOUT_START
: RenderState.INVALID_LAYOUT;
case View.FOCUS_DOWN:
return mOrientation == VERTICAL ? RenderState.LAYOUT_END
: RenderState.INVALID_LAYOUT;
case View.FOCUS_LEFT:
return mOrientation == HORIZONTAL ? RenderState.LAYOUT_START
: RenderState.INVALID_LAYOUT;
case View.FOCUS_RIGHT:
return mOrientation == HORIZONTAL ? RenderState.LAYOUT_END
: RenderState.INVALID_LAYOUT;
default:
if (DEBUG) {
Log.d(TAG, "Unknown focus request:" + focusDirection);
}
return RenderState.INVALID_LAYOUT;
}
}
/**
* Converts a focusDirection to orientation.
*
* @param focusDirection One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN},
* {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT},
* {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD}
* or 0 for not applicable
* @return {@link LayoutState#LAYOUT_START} or {@link LayoutState#LAYOUT_END} if focus direction
* is applicable to current state, {@link LayoutState#INVALID_LAYOUT} otherwise.
*/
private int convertFocusDirectionToLayoutDirection(int focusDirection) {
switch (focusDirection) {
case View.FOCUS_BACKWARD:
return LayoutState.LAYOUT_START;
case View.FOCUS_FORWARD:
return LayoutState.LAYOUT_END;
case View.FOCUS_UP:
return mOrientation == VERTICAL ? LayoutState.LAYOUT_START
: LayoutState.INVALID_LAYOUT;
case View.FOCUS_DOWN:
return mOrientation == VERTICAL ? LayoutState.LAYOUT_END
: LayoutState.INVALID_LAYOUT;
case View.FOCUS_LEFT:
return mOrientation == HORIZONTAL ? LayoutState.LAYOUT_START
: LayoutState.INVALID_LAYOUT;
case View.FOCUS_RIGHT:
return mOrientation == HORIZONTAL ? LayoutState.LAYOUT_END
: LayoutState.INVALID_LAYOUT;
default:
if (DEBUG) {
Log.d(TAG, "Unknown focus request:" + focusDirection);
}
return LayoutState.INVALID_LAYOUT;
}
}
/**
* Converts a focusDirection to orientation.
*
* @param focusDirection One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN},
* {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT},
* {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD}
* or 0 for not applicable
* @return {@link LayoutState#LAYOUT_START} or {@link LayoutState#LAYOUT_END} if focus direction
* is applicable to current state, {@link LayoutState#INVALID_LAYOUT} otherwise.
*/
private int convertFocusDirectionToLayoutDirectionExpose(int focusDirection) {
int orientation = getOrientation();
switch (focusDirection) {
case View.FOCUS_BACKWARD:
return LayoutState.LAYOUT_START;
case View.FOCUS_FORWARD:
return LayoutState.LAYOUT_END;
case View.FOCUS_UP:
return orientation == VERTICAL ? LayoutState.LAYOUT_START
: LayoutState.INVALID_LAYOUT;
case View.FOCUS_DOWN:
return orientation == VERTICAL ? LayoutState.LAYOUT_END
: LayoutState.INVALID_LAYOUT;
case View.FOCUS_LEFT:
return orientation == HORIZONTAL ? LayoutState.LAYOUT_START
: LayoutState.INVALID_LAYOUT;
case View.FOCUS_RIGHT:
return orientation == HORIZONTAL ? LayoutState.LAYOUT_END
: LayoutState.INVALID_LAYOUT;
default:
if (DEBUG) {
Log.d(TAG, "Unknown focus request:" + focusDirection);
}
return LayoutState.INVALID_LAYOUT;
}
}
/**
* When looking for focus in children of a scroll view, need to be a little
* more careful not to give focus to something that is scrolled off screen.
*
* This is more expensive than the default {@link ViewGroup}
* implementation, otherwise this behavior might have been made the default.
*/
@Override
protected boolean onRequestFocusInDescendants(int direction,
Rect previouslyFocusedRect) {
// convert from forward / backward notation to up / down / left / right
// (ugh).
if (direction == View.FOCUS_FORWARD) {
direction = View.FOCUS_DOWN;
} else if (direction == View.FOCUS_BACKWARD) {
direction = View.FOCUS_UP;
}
final View nextFocus = previouslyFocusedRect == null
? FocusFinder.getInstance().findNextFocus(this, null, direction)
: FocusFinder.getInstance().findNextFocusFromRect(
this, previouslyFocusedRect, direction);
if (nextFocus == null) {
return false;
}
if (isOffScreen(nextFocus)) {
return false;
}
return nextFocus.requestFocus(direction, previouslyFocusedRect);
}
/**
* Converts a focusDirection to orientation.
*
* @param focusDirection One of {@link android.view.View#FOCUS_UP}, {@link android.view.View#FOCUS_DOWN},
* {@link android.view.View#FOCUS_LEFT}, {@link android.view.View#FOCUS_RIGHT},
* {@link android.view.View#FOCUS_BACKWARD}, {@link android.view.View#FOCUS_FORWARD}
* or 0 for not applicable
* @return {@link com.twotoasters.android.support.v7.widget.LinearLayoutManager.RenderState#LAYOUT_START} or {@link com.twotoasters.android.support.v7.widget.LinearLayoutManager.RenderState#LAYOUT_END} if focus direction
* is applicable to current state, {@link com.twotoasters.android.support.v7.widget.LinearLayoutManager.RenderState#INVALID_LAYOUT} otherwise.
*/
private int convertFocusDirectionToLayoutDirection(int focusDirection) {
switch (focusDirection) {
case View.FOCUS_BACKWARD:
return RenderState.LAYOUT_START;
case View.FOCUS_FORWARD:
return RenderState.LAYOUT_END;
case View.FOCUS_UP:
return mOrientation == VERTICAL ? RenderState.LAYOUT_START
: RenderState.INVALID_LAYOUT;
case View.FOCUS_DOWN:
return mOrientation == VERTICAL ? RenderState.LAYOUT_END
: RenderState.INVALID_LAYOUT;
case View.FOCUS_LEFT:
return mOrientation == HORIZONTAL ? RenderState.LAYOUT_START
: RenderState.INVALID_LAYOUT;
case View.FOCUS_RIGHT:
return mOrientation == HORIZONTAL ? RenderState.LAYOUT_END
: RenderState.INVALID_LAYOUT;
default:
if (DEBUG) {
Log.d(TAG, "Unknown focus request:" + focusDirection);
}
return RenderState.INVALID_LAYOUT;
}
}
/**
* Converts a focusDirection to orientation.
*
* @param focusDirection One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN},
* {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT},
* {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD}
* or 0 for not applicable
* @return {@link LayoutState#LAYOUT_START} or {@link LayoutState#LAYOUT_END} if focus direction
* is applicable to current state, {@link LayoutState#INVALID_LAYOUT} otherwise.
*/
private int convertFocusDirectionToLayoutDirection(int focusDirection) {
switch (focusDirection) {
case View.FOCUS_BACKWARD:
if (mOrientation == VERTICAL) {
return LayoutState.LAYOUT_START;
} else if (isLayoutRTL()) {
return LayoutState.LAYOUT_END;
} else {
return LayoutState.LAYOUT_START;
}
case View.FOCUS_FORWARD:
if (mOrientation == VERTICAL) {
return LayoutState.LAYOUT_END;
} else if (isLayoutRTL()) {
return LayoutState.LAYOUT_START;
} else {
return LayoutState.LAYOUT_END;
}
case View.FOCUS_UP:
return mOrientation == VERTICAL ? LayoutState.LAYOUT_START
: LayoutState.INVALID_LAYOUT;
case View.FOCUS_DOWN:
return mOrientation == VERTICAL ? LayoutState.LAYOUT_END
: LayoutState.INVALID_LAYOUT;
case View.FOCUS_LEFT:
return mOrientation == HORIZONTAL ? LayoutState.LAYOUT_START
: LayoutState.INVALID_LAYOUT;
case View.FOCUS_RIGHT:
return mOrientation == HORIZONTAL ? LayoutState.LAYOUT_END
: LayoutState.INVALID_LAYOUT;
default:
if (DEBUG) {
Log.d(TAG, "Unknown focus request:" + focusDirection);
}
return LayoutState.INVALID_LAYOUT;
}
}
/**
* When looking for focus in children of a scroll view, need to be a little more careful not to
* give focus to something that is scrolled off screen.
*
* <p>This is more expensive than the default {@link ViewGroup} implementation,
* otherwise this behavior might have been made the default.</p>
*/
@Override
protected boolean onRequestFocusInDescendants(int direction, Rect previouslyFocusedRect) {
// convert from forward / backward notation to up / down / left / right
if (direction == View.FOCUS_FORWARD) {
direction = View.FOCUS_DOWN;
} else if (direction == View.FOCUS_BACKWARD) {
direction = View.FOCUS_UP;
}
View nextFocus = previouslyFocusedRect == null ? FocusFinder.getInstance().findNextFocus(this, null, direction) :
FocusFinder.getInstance().findNextFocusFromRect(this, previouslyFocusedRect, direction);
return nextFocus != null && nextFocus.requestFocus(direction, previouslyFocusedRect);
}
static int getDistance(Rect source, Rect dest, int direction) {
int sX, sY;
int dX, dY;
switch (direction) {
case View.FOCUS_RIGHT:
sX = source.right;
sY = source.top + source.height() / 2;
dX = dest.left;
dY = dest.top + dest.height() / 2;
break;
case View.FOCUS_DOWN:
sX = source.left + source.width() / 2;
sY = source.bottom;
dX = dest.left + dest.width() / 2;
dY = dest.top;
break;
case View.FOCUS_LEFT:
sX = source.left;
sY = source.top + source.height() / 2;
dX = dest.right;
dY = dest.top + dest.height() / 2;
break;
case View.FOCUS_UP:
sX = source.left + source.width() / 2;
sY = source.top;
dX = dest.left + dest.width() / 2;
dY = dest.bottom;
break;
case View.FOCUS_FORWARD:
case View.FOCUS_BACKWARD:
sX = source.right + source.width() / 2;
sY = source.top + source.height() / 2;
dX = dest.left + dest.width() / 2;
dY = dest.top + dest.height() / 2;
break;
default:
throw new IllegalArgumentException("direction must be one of "
+ "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT, " +
"FOCUS_FORWARD, FOCUS_BACKWARD}.");
}
int deltaX = dX - sX;
int deltaY = dY - sY;
return deltaY * deltaY + deltaX * deltaX;
}
/**
* Is childIndex a candidate for next focus given the direction the focus
* change is coming from?
* @param childIndex The index to check.
* @param direction The direction, one of
* {FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT, FOCUS_FORWARD, FOCUS_BACKWARD}
* @return Whether childIndex is a candidate.
*/
private boolean isCandidateSelection(int childIndex, int direction) {
final int count = getChildCount();
final int invertedIndex = count - 1 - childIndex;
int rowStart;
int rowEnd;
if (!mStackFromBottom) {
rowStart = childIndex - (childIndex % mNumColumns);
rowEnd = Math.min(rowStart + mNumColumns - 1, count);
} else {
rowEnd = count - 1 - (invertedIndex - (invertedIndex % mNumColumns));
rowStart = Math.max(0, rowEnd - mNumColumns + 1);
}
switch (direction) {
case View.FOCUS_RIGHT:
// coming from left, selection is only valid if it is on left
// edge
return childIndex == rowStart;
case View.FOCUS_DOWN:
// coming from top; only valid if in top row
return rowStart == 0;
case View.FOCUS_LEFT:
// coming from right, must be on right edge
return childIndex == rowEnd;
case View.FOCUS_UP:
// coming from bottom, need to be in last row
return rowEnd == count - 1;
case View.FOCUS_FORWARD:
// coming from top-left, need to be first in top row
return childIndex == rowStart && rowStart == 0;
case View.FOCUS_BACKWARD:
// coming from bottom-right, need to be last in bottom row
return childIndex == rowEnd && rowEnd == count - 1;
default:
throw new IllegalArgumentException("direction must be one of "
+ "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT, "
+ "FOCUS_FORWARD, FOCUS_BACKWARD}.");
}
}
/**
* Is childIndex a candidate for next focus given the direction the focus
* change is coming from?
* @param childIndex The index to check.
* @param direction The direction, one of
* {FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}
* @return Whether childIndex is a candidate.
*/
@Override
protected boolean isCandidateSelection(int childIndex, int direction) {
final int count = getChildCount();
final int invertedIndex = count - 1 - childIndex;
int rowStart;
int rowEnd;
if (!mStackFromBottom) {
rowStart = childIndex - (childIndex % mNumColumns);
rowEnd = Math.max(rowStart + mNumColumns - 1, count);
} else {
rowEnd = count - 1 - (invertedIndex - (invertedIndex % mNumColumns));
rowStart = Math.max(0, rowEnd - mNumColumns + 1);
}
switch (direction) {
case View.FOCUS_RIGHT:
// coming from left, selection is only valid if it is on left
// edge
return childIndex == rowStart;
case View.FOCUS_DOWN:
// coming from top; only valid if in top row
return rowStart == 0;
case View.FOCUS_LEFT:
// coming from right, must be on right edge
return childIndex == rowEnd;
case View.FOCUS_UP:
// coming from bottom, need to be in last row
return rowEnd == count - 1;
case View.FOCUS_FORWARD:
// coming from top-left, need to be first in top row
return childIndex == rowStart && rowStart == 0;
case View.FOCUS_BACKWARD:
// coming from bottom-right, need to be last in bottom row
return childIndex == rowEnd && rowEnd == count - 1;
default:
throw new IllegalArgumentException("direction must be one of "
+ "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT, "
+ "FOCUS_FORWARD, FOCUS_BACKWARD}");
}
}
static int getDistance(Rect source, Rect dest, int direction) {
int sX, sY;
int dX, dY;
switch (direction) {
case View.FOCUS_RIGHT:
sX = source.right;
sY = source.top + source.height() / 2;
dX = dest.left;
dY = dest.top + dest.height() / 2;
break;
case View.FOCUS_DOWN:
sX = source.left + source.width() / 2;
sY = source.bottom;
dX = dest.left + dest.width() / 2;
dY = dest.top;
break;
case View.FOCUS_LEFT:
sX = source.left;
sY = source.top + source.height() / 2;
dX = dest.right;
dY = dest.top + dest.height() / 2;
break;
case View.FOCUS_UP:
sX = source.left + source.width() / 2;
sY = source.top;
dX = dest.left + dest.width() / 2;
dY = dest.bottom;
break;
case View.FOCUS_FORWARD:
case View.FOCUS_BACKWARD:
sX = source.right + source.width() / 2;
sY = source.top + source.height() / 2;
dX = dest.left + dest.width() / 2;
dY = dest.top + dest.height() / 2;
break;
default:
throw new IllegalArgumentException("direction must be one of "
+ "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT, "
+ "FOCUS_FORWARD, FOCUS_BACKWARD}.");
}
int deltaX = dX - sX;
int deltaY = dY - sY;
return deltaY * deltaY + deltaX * deltaX;
}
/**
* Is childIndex a candidate for next focus given the direction the focus
* change is coming from?
* @param childIndex The index to check.
* @param direction The direction, one of
* {FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}
* @return Whether childIndex is a candidate.
*/
@Override
protected boolean isCandidateSelection(int childIndex, int direction) {
final int count = getChildCount();
final int invertedIndex = count - 1 - childIndex;
final int numRows = mNumRows;
int columnStart;
int columnEnd;
if (!mStackFromBottom) {
columnStart = childIndex - (childIndex % numRows);
columnEnd = Math.max(columnStart + numRows - 1, count);
} else {
columnEnd = count - 1 - (invertedIndex - (invertedIndex % numRows));
columnStart = Math.max(0, columnEnd - numRows + 1);
}
switch (direction) {
case View.FOCUS_RIGHT:
// coming from left, selection is only valid if it is on left
// edge
return childIndex == columnStart;
case View.FOCUS_DOWN:
// coming from top; only valid if in top row
return columnStart == 0;
case View.FOCUS_LEFT:
// coming from right, must be on right edge
return childIndex == columnStart;
case View.FOCUS_UP:
// coming from bottom, need to be in last row
return columnStart == count - 1;
case View.FOCUS_FORWARD:
// coming from top-left, need to be first in top row
return childIndex == columnStart && columnStart == 0;
case View.FOCUS_BACKWARD:
// coming from bottom-right, need to be last in bottom row
return childIndex == columnEnd && columnEnd == count - 1;
default:
throw new IllegalArgumentException("direction must be one of "
+ "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT, "
+ "FOCUS_FORWARD, FOCUS_BACKWARD}.");
}
}