1 files changed, 76 insertions, 0 deletions
diff --git a/src/main/java/de/pixart/messenger/ui/util/GridManager.java b/src/main/java/de/pixart/messenger/ui/util/GridManager.java
new file mode 100644
index 000000000..ae615b051
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/ui/util/GridManager.java
@@ -0,0 +1,76 @@
+package de.pixart.messenger.ui.util;
+
+import android.content.Context;
+import android.support.annotation.DimenRes;
+import android.support.v7.widget.GridLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.util.Log;
+import android.view.ViewTreeObserver;
+
+import de.pixart.messenger.Config;
+import de.pixart.messenger.ui.adapter.MediaAdapter;
+
+public class GridManager {
+
+    public static void setupLayoutManager(final Context context, RecyclerView recyclerView, @DimenRes int desiredSize) {
+        int maxWidth = context.getResources().getDisplayMetrics().widthPixels;
+        ColumnInfo columnInfo = calculateColumnCount(context, maxWidth, desiredSize);
+        Log.d(Config.LOGTAG, "preliminary count=" + columnInfo.count);
+        MediaAdapter.setMediaSize(recyclerView, columnInfo.width);
+        recyclerView.setLayoutManager(new GridLayoutManager(context, columnInfo.count));
+        recyclerView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
+            @Override
+            public void onGlobalLayout() {
+                recyclerView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
+                final int availableWidth = recyclerView.getMeasuredWidth();
+                if (availableWidth == 0) {
+                    Log.e(Config.LOGTAG, "GridManager: available width was 0; probably because layout was hidden");
+                    return;
+                }
+                final ColumnInfo columnInfo = calculateColumnCount(context, recyclerView.getMeasuredWidth(), desiredSize);
+                Log.d(Config.LOGTAG, "final count " + columnInfo.count);
+                if (recyclerView.getAdapter().getItemCount() != 0) {
+                    Log.e(Config.LOGTAG, "adapter already has items; just go with it now");
+                    return;
+                }
+                setupLayoutManagerInternal(recyclerView, columnInfo);
+                MediaAdapter.setMediaSize(recyclerView, columnInfo.width);
+            }
+        });
+    }
+
+    private static void setupLayoutManagerInternal(RecyclerView recyclerView, final ColumnInfo columnInfo) {
+        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
+        if (layoutManager instanceof GridLayoutManager) {
+            ((GridLayoutManager) layoutManager).setSpanCount(columnInfo.count);
+        }
+    }
+
+    private static ColumnInfo calculateColumnCount(Context context, int availableWidth, @DimenRes int desiredSize) {
+        final float desiredWidth = context.getResources().getDimension(desiredSize);
+        final int columns = Math.round(availableWidth / desiredWidth);
+        final int realWidth = availableWidth / columns;
+        Log.d(Config.LOGTAG, "desired=" + desiredWidth + " real=" + realWidth);
+        return new ColumnInfo(columns, realWidth);
+    }
+
+    public static int getCurrentColumnCount(RecyclerView recyclerView) {
+        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
+        if (layoutManager instanceof GridLayoutManager) {
+            return ((GridLayoutManager) layoutManager).getSpanCount();
+        } else {
+            return 0;
+        }
+    }
+
+    public static class ColumnInfo {
+        private final int count;
+        private final int width;
+
+        private ColumnInfo(int count, int width) {
+            this.count = count;
+            this.width = width;
+        }
+    }
+
+}
+\ No newline at end of file