org.primefaces.component.datatable.feature.ScrollFeature Maven / Gradle / Ivy

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/**
 * Copyright 2009-2018 PrimeTek.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.primefaces.component.datatable.feature;

import java.io.IOException;
import java.util.Map;
import javax.faces.context.FacesContext;
import org.primefaces.component.datatable.DataTable;
import org.primefaces.component.datatable.DataTableRenderer;

public class ScrollFeature implements DataTableFeature {

    public void decode(FacesContext context, DataTable table) {
        throw new RuntimeException("RowScrollFeature should not decode.");
    }

    public void encode(FacesContext context, DataTableRenderer renderer, DataTable table) throws IOException {
        Map params = context.getExternalContext().getRequestParameterMap();
        int scrollRows = table.getScrollRows();
        String clientId = table.getClientId(context);
        boolean isVirtualScroll = table.isVirtualScroll();
        boolean isLazy = table.isLazy();
        int scrollOffset = 0;

        if (isVirtualScroll) {
            scrollOffset = Integer.parseInt(params.get(table.getClientId(context) + "_first"));
            int rowCount = table.getRowCount();
            int virtualScrollRows = (scrollRows * 2);
            scrollRows = (scrollOffset + virtualScrollRows) > rowCount ? (rowCount - scrollOffset) : virtualScrollRows;
        }
        else {
            scrollOffset = Integer.parseInt(params.get(table.getClientId(context) + "_scrollOffset"));
            table.setScrollOffset(scrollOffset);
        }

        if (isLazy) {
            table.loadLazyScrollData(scrollOffset, scrollRows);
        }

        if (table.isSelectionEnabled()) {
            table.findSelectedRowKeys();
        }

        int firstIndex = (isLazy && isVirtualScroll) ? 0 : scrollOffset;
        int lastIndex = (firstIndex + scrollRows);

        for (int i = firstIndex; i < lastIndex; i++) {
            table.setRowIndex(i);

            if (table.isRowAvailable()) {
                int rowIndex = (isLazy && isVirtualScroll) ? scrollOffset + i : i;
                renderer.encodeRow(context, table, clientId, rowIndex);
            }
        }
    }

    public boolean shouldDecode(FacesContext context, DataTable table) {
        return false;
    }

    public boolean shouldEncode(FacesContext context, DataTable table) {
        return context.getExternalContext().getRequestParameterMap().containsKey(table.getClientId(context) + "_scrolling");
    }

}