/**
* Adjusts the given row if possible to fit within the layout span. By default this will try to
* find the highest break weight possible nearest the end of the row. If a forced break is
* encountered, the break will be positioned there.
*
* @param rowIndex the row to adjust to the current layout span.
* @param desiredSpan the current layout span >= 0
* @param x the location r starts at.
*/
protected void adjustRow(FlowView fv, int rowIndex, int desiredSpan, int x) {
final int flowAxis = fv.getFlowAxis();
View r = fv.getView(rowIndex);
int n = r.getViewCount();
int span = 0;
int bestWeight = BadBreakWeight;
int bestSpan = 0;
int bestIndex = -1;
int bestOffset = 0;
View v;
for (int i = 0; i < n; i++) {
v = r.getView(i);
int spanLeft = desiredSpan - span;
int w = v.getBreakWeight(flowAxis, x + span, spanLeft);
if ((w >= bestWeight) && (w > BadBreakWeight)) {
bestWeight = w;
bestIndex = i;
bestSpan = span;
if (w >= ForcedBreakWeight) {
// it's a forced break, so there is
// no point in searching further.
break;
}
}
span += v.getPreferredSpan(flowAxis);
}
if (bestIndex < 0) {
// there is nothing that can be broken, leave
// it in it's current state.
return;
}
// Break the best candidate view, and patch up the row.
int spanLeft = desiredSpan - bestSpan;
v = r.getView(bestIndex);
v = v.breakView(flowAxis, v.getStartOffset(), x + bestSpan, spanLeft);
View[] va = new View[1];
va[0] = v;
View lv = getLogicalView(fv);
for (int i = bestIndex; i < n; i++) {
View tmpView = r.getView(i);
if (contains(lv, tmpView)) {
tmpView.setParent(lv);
} else if (tmpView.getViewCount() > 0) {
recursiveReparent(tmpView, lv);
}
}
r.replace(bestIndex, n - bestIndex, va);
}
/**
* Update the flow on the given FlowView. By default, this causes all of the rows (child views)
* to be rebuilt to match the given constraints for each row. This is called by a
* FlowView.layout to update the child views in the flow.
*
* @param fv the view to reflow
*/
public void layout(FlowView fv) {
int p0 = fv.getStartOffset();
int p1 = fv.getEndOffset();
// we want to preserve all views from the logicalView from being
// removed
View lv = getLogicalView(fv);
int n = lv.getViewCount();
for (int i = 0; i < n; i++) {
View v = lv.getView(i);
v.setParent(lv);
}
fv.removeAll();
for (int rowIndex = 0; p0 < p1; rowIndex++) {
View row = fv.createRow();
fv.append(row);
// layout the row to the current span. If nothing fits,
// force something.
int next = layoutRow(fv, rowIndex, p0);
if (row.getViewCount() == 0) {
row.append(createView(fv, p0, Integer.MAX_VALUE, rowIndex));
next = row.getEndOffset();
}
if (next <= p0) {
throw new StateInvariantError("infinite loop in formatting");
} else {
p0 = next;
}
}
}
private boolean contains(View logicalView, View v) {
int n = logicalView.getViewCount();
for (int i = 0; i < n; i++) {
if (logicalView.getView(i) == v) {
return true;
}
}
return false;
}
private void recursiveReparent(View v, View logicalView) {
int n = v.getViewCount();
for (int i = 0; i < n; i++) {
View tmpView = v.getView(i);
if (contains(logicalView, tmpView)) {
tmpView.setParent(logicalView);
} else {
recursiveReparent(tmpView, logicalView);
}
}
}
/**
* Creates a view that can be used to represent the current piece of the flow. This can be
* either an entire view from the logical view, or a fragment of the logical view.
*
* @param fv the view holding the flow
* @param startOffset the start location for the view being created
* @param spanLeft the about of span left to fill in the row
* @param rowIndex the row the view will be placed into
*/
protected View createView(FlowView fv, int startOffset, int spanLeft, int rowIndex) {
// Get the child view that contains the given starting position
View lv = getLogicalView(fv);
int childIndex = lv.getViewIndex(startOffset, Position.Bias.Forward);
View v = lv.getView(childIndex);
if (startOffset == v.getStartOffset()) {
// return the entire view
return v;
}
// return a fragment.
v = v.createFragment(startOffset, v.getEndOffset());
return v;
}