Add stacked events

app/src/main/java/com/android/calendar/DayView.java

@@ -87,6 +87,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Calendar;
+import java.util.Comparator;
 import java.util.Formatter;
 import java.util.Locale;
 import java.util.regex.Matcher;
@@ -3133,6 +3134,12 @@ private void drawEvents(int date, int dayIndex, int top, Canvas canvas, Paint p)
         selectionArea.right = selectionArea.left + cellWidth;
 
         final ArrayList<Event> events = mEvents;
+
+        // Sort events by column, so they are drawn in order of column. This
+        // leads to events with the higher column number being drawn last, which
+        // ensures proper z-sorting when multiple events overlap.
+        events.sort(Comparator.comparingInt(Event::getColumn));
+
         int numEvents = events.size();
         EventGeometry geometry = mEventGeometry;
 
@@ -3163,6 +3170,7 @@ private void drawEvents(int date, int dayIndex, int top, Canvas canvas, Paint p)
             if (r.top > viewEndY || r.bottom < mViewStartY) {
                 continue;
             }
+
             StaticLayout layout = getEventLayout(mLayouts, i, event, eventTextPaint, r);
             // TODO: not sure why we are 4 pixels off
             drawEventText(layout, r, canvas, mViewStartY + 4, mViewStartY + mViewHeight
@@ -4762,16 +4770,24 @@ private void findSelectedEvent(int x, int y) {
 
         // If there are any events in the selected region, then assign the
         // closest one to mSelectedEvent.
-        if (mSelectedEvents.size() > 0) {
+        if (!mSelectedEvents.isEmpty()) {
             int len = mSelectedEvents.size();
             Event closestEvent = null;
             float minDist = mViewWidth + mViewHeight; // some large distance
+            float maxCol = -99999;
             for (int index = 0; index < len; index++) {
                 Event ev = mSelectedEvents.get(index);
+
+                // dist will yield 0.0 for all events overlapping each other.
+                // In order to select the correct one we use the topmost event (i.e. the one with
+                // the highest col value!
+
                 float dist = geometry.pointToEvent(x, y, ev);
-                if (dist < minDist) {
+                float col  = ev.getColumn();
+                if (dist <= minDist && col > maxCol) {
                     minDist = dist;
                     closestEvent = ev;
+                    maxCol = col;
                 }
             }
             setSelectedEvent(closestEvent);

app/src/main/java/com/android/calendar/EventGeometry.java

@@ -24,6 +24,11 @@ public class EventGeometry {
 
     private float mMinuteHeight;
 
+    // How many pixels is each column set off from the
+    // very left of column 0?
+    // This is used to enable stacked parallel events.
+    private static final float mPerColMargin  = 32;
+
     private float mHourGap;
     private float mMinEventHeight;
 
@@ -97,8 +102,9 @@ public boolean computeEventRect(int date, int left, int top, int cellWidth, Even
             event.bottom = event.top + mMinEventHeight;
         }
 
-        float colWidth = (float) (cellWidth - (maxCols + 1) * mCellMargin) / (float) maxCols;
-        event.left = left + col * (colWidth + mCellMargin);
+
+        float colWidth = (float) (cellWidth - (maxCols) * mCellMargin) - (float) (col * mPerColMargin);
+        event.left = left + (col) * mPerColMargin;
         event.right = event.left + colWidth;
         return true;
     }