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); int columns = Math.round(availableWidth / desiredWidth); if (columns < 1) { columns = 1; } 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; } } }