Table: added scroll listeners ( no handling and some bug gives wrong rows )

svn changeset:1697/svn branch:trunk

diff --git a/src/com/itmill/toolkit/terminal/gwt/client/ui/TkTable.java b/src/com/itmill/toolkit/terminal/gwt/client/ui/TkTable.java
index d788c266c78aa53c582194e5a4016d89ba71e8e2..1c79acb9931123d4459f7551764402523cb9d891 100644 (file)
--- a/src/com/itmill/toolkit/terminal/gwt/client/ui/TkTable.java
+++ b/src/com/itmill/toolkit/terminal/gwt/client/ui/TkTable.java
@@ -8,9 +8,11 @@ import com.google.gwt.user.client.Command;
 import com.google.gwt.user.client.DOM;
 import com.google.gwt.user.client.DeferredCommand;
 import com.google.gwt.user.client.Element;
+import com.google.gwt.user.client.Timer;
 import com.google.gwt.user.client.ui.Composite;
 import com.google.gwt.user.client.ui.FlexTable;
 import com.google.gwt.user.client.ui.HTML;
+import com.google.gwt.user.client.ui.ScrollListener;
 import com.google.gwt.user.client.ui.ScrollPanel;
 import com.google.gwt.user.client.ui.VerticalPanel;
 import com.google.gwt.user.client.ui.Widget;
@@ -19,11 +21,22 @@ import com.itmill.toolkit.terminal.gwt.client.Client;
 import com.itmill.toolkit.terminal.gwt.client.Paintable;
 import com.itmill.toolkit.terminal.gwt.client.UIDL;
 
-public class TkTable extends Composite implements Paintable {
+public class TkTable extends Composite implements Paintable, ScrollListener {
+       
+       /**
+        *  multiple of pagelenght which component will 
+        *  cache when requesting more rows 
+        */
+       private static final double CACHE_RATE = 3;
+       /** 
+        * fraction of pageLenght which can be scrolled without 
+        * making new request 
+        */
+       private static final double CACHE_REACT_RATE = 1;
        
        private int firstRendered = 0;
        private int lastRendered = 0;
-       private int firstRowInViewPort = 0;
+       private int firstRowInViewPort = 1;
        private int pageLength = 15;
        
        private int rowHeaders = 0;
@@ -49,6 +62,9 @@ public class TkTable extends Composite implements Paintable {
        private int totalRows;
        private HashMap columnWidths = new HashMap();
        
+       private int rowHeight = 22;
+       private RowRequestHandler rowRequestHandler;
+       
        public TkTable() {
                headerContainer.add(tHead);
                DOM.setStyleAttribute(headerContainer.getElement(), "overflow", "hidden");
@@ -57,13 +73,16 @@ public class TkTable extends Composite implements Paintable {
                bodyContent.add(tBody);
                bodyContent.add(postSpacer);
                //TODO remove debug color
-               DOM.setStyleAttribute(postSpacer.getElement(), "background", "red");
+               DOM.setStyleAttribute(postSpacer.getElement(), "background", "gray");
                bodyContainer.add(bodyContent);
+               bodyContainer.addScrollListener(this);
                
                VerticalPanel panel = new VerticalPanel();
                panel.add(headerContainer);
                panel.add(bodyContainer);
                
+               rowRequestHandler = new RowRequestHandler();
+               
                initWidget(panel);
        }
 
@@ -87,6 +106,7 @@ public class TkTable extends Composite implements Paintable {
                                ;
                }
                updateHeader(columnInfo);
+               
                updateBody(rowData);
                
                if(!colWidthsInitialized) {
@@ -212,7 +232,7 @@ public class TkTable extends Composite implements Paintable {
        }
        
        private void updateSpacers() {
-               int rowHeight = tBody.getOffsetHeight()/getRenderedRowCount();
+               rowHeight = tBody.getOffsetHeight()/getRenderedRowCount();
                int preSpacerHeight = (firstRendered - 1)*rowHeight;
                int postSpacerHeight = (totalRows - lastRendered)*rowHeight;
                preSpacer.setHeight(preSpacerHeight+"px");
@@ -223,5 +243,78 @@ public class TkTable extends Composite implements Paintable {
                return lastRendered-firstRendered;
        }
 
+       /**
+        * This method has logick which rows needs to be requested from
+        * server when user scrolls
+        *
+        */
+       public void onScroll(Widget widget, int scrollLeft, int scrollTop) {
+               rowRequestHandler.cancel();
+               
+               firstRowInViewPort = scrollTop / rowHeight;
+               client.console.log("At scrolltop: " + scrollTop + " At row " + firstRowInViewPort);
+               
+               int postLimit = (int) (firstRowInViewPort + pageLength + pageLength*CACHE_REACT_RATE);
+               int preLimit = (int) (firstRowInViewPort - pageLength*CACHE_REACT_RATE);
+               if(
+                               postLimit > lastRendered &&
+                               ( preLimit < 1 || preLimit < firstRendered )
+                               ) {
+                       client.updateVariable(this.id, "firstvisible", firstRowInViewPort, false);
+                       return; // scrolled withing "non-react area"
+               }
+               
+               if(firstRowInViewPort - pageLength*CACHE_RATE > lastRendered ||
+                               firstRowInViewPort + pageLength + pageLength*CACHE_RATE < firstRendered ) {
+                       // need a totally new set
+                       client.console.log("Table: need a totally new set");
+                       rowRequestHandler.setReqFirstRow((int) (firstRowInViewPort - pageLength*CACHE_RATE));
+                       rowRequestHandler.setReqRows((int) (2*CACHE_RATE*pageLength + pageLength));
+                       rowRequestHandler.deferRowFetch();
+                       return;
+               }
+               if(preLimit < firstRendered ) {
+                       // need some rows to the beginning of the rendered area
+                       client.console.log("Table: need some rows to the beginning of the rendered area");
+                       rowRequestHandler.setReqFirstRow((int) (firstRowInViewPort - pageLength*CACHE_RATE));
+                       rowRequestHandler.setReqRows((int) (2*CACHE_RATE*pageLength + pageLength));
+                       rowRequestHandler.deferRowFetch();
 
+                       return;
+               }
+               if(postLimit > lastRendered) {
+                       // need some rows to the end of the rendered area
+                       client.console.log("need some rows to the end of the rendered area");
+                       rowRequestHandler.setReqFirstRow(lastRendered + 1);
+                       rowRequestHandler.setReqRows((int) ((firstRowInViewPort + pageLength + pageLength*CACHE_RATE) - lastRendered));
+                       rowRequestHandler.deferRowFetch();
+               }
+       }
+       
+       private class RowRequestHandler extends Timer {
+               
+               private int reqFirstRow;
+               private int reqRows;
+               
+               public void deferRowFetch() {
+                       schedule(250);
+               }
+
+               public void setReqFirstRow(int reqFirstRow) {
+                       if(reqFirstRow < 1)
+                               reqFirstRow = 1;
+                       this.reqFirstRow = reqFirstRow;
+               }
+
+               public void setReqRows(int reqRows) {
+                       this.reqRows = reqRows;
+               }
+
+               public void run() {
+//                     client.updateVariable(id, "firstvisible", firstRowInViewPort, false);
+                       client.updateVariable(id, "reqfirstrow", reqFirstRow, false);
+                       client.updateVariable(id, "reqrows", reqRows, true);
+               }
+               
+       }
 }