Reimplement basic Grid renderers

Change-Id: Ic855143d23cc7735d00130806df45b6579ba0d5c

9 files changed, 886 insertions, 25 deletions

diff --git a/server/src/main/java/com/vaadin/ui/Grid.java b/server/src/main/java/com/vaadin/ui/Grid.java
index 387cd22275..22b5ef8072 100644
--- a/server/src/main/java/com/vaadin/ui/Grid.java
+++ b/server/src/main/java/com/vaadin/ui/Grid.java
@@ -46,9 +46,12 @@ import com.vaadin.shared.ui.grid.GridConstants.Section;
 import com.vaadin.shared.ui.grid.GridServerRpc;
 import com.vaadin.shared.ui.grid.GridState;
 import com.vaadin.shared.ui.grid.HeightMode;
+import com.vaadin.ui.renderers.Renderer;
+import com.vaadin.ui.renderers.TextRenderer;
 
 import elemental.json.Json;
 import elemental.json.JsonObject;
+import elemental.json.JsonValue;
 
 /**
  * A grid component for displaying tabular data.
@@ -305,49 +308,99 @@ public class Grid<T> extends AbstractListing<T, SelectionModel<T>>
     public static class Column<T, V> extends AbstractExtension
             implements DataGenerator<T> {
 
-        private Function<T, V> valueProvider;
+        private final Function<T, ? extends V> valueProvider;
+
         private Function<SortDirection, Stream<SortOrder<String>>> sortOrderProvider;
         private Comparator<T> comparator;
 
         /**
-         * Constructs a new Column configuration with given header caption and
-         * value provider.
+         * Constructs a new Column configuration with given header caption,
+         * renderer and value provider.
          *
          * @param caption
          *            the header caption
-         * @param valueType
-         *            the type of value
          * @param valueProvider
          *            the function to get values from items
+         * @param renderer
+         *            the type of value
          */
-        protected Column(String caption, Class<V> valueType,
-                Function<T, V> valueProvider) {
+        protected Column(String caption, Function<T, ? extends V> valueProvider,
+                Renderer<V> renderer) {
             Objects.requireNonNull(caption, "Header caption can't be null");
             Objects.requireNonNull(valueProvider,
                     "Value provider can't be null");
-            Objects.requireNonNull(valueType, "Value type can't be null");
+            Objects.requireNonNull(renderer, "Renderer can't be null");
+
+            ColumnState state = getState();
 
             this.valueProvider = valueProvider;
-            getState().caption = caption;
+            state.renderer = renderer;
+
+            state.caption = caption;
             sortOrderProvider = d -> Stream.of();
 
+            // Add the renderer as a child extension of this extension, thus
+            // ensuring the renderer will be unregistered when this column is
+            // removed
+            addExtension(renderer);
+
+            Class<V> valueType = renderer.getPresentationType();
+
             if (Comparable.class.isAssignableFrom(valueType)) {
                 comparator = (a, b) -> {
                     @SuppressWarnings("unchecked")
                     Comparable<V> comp = (Comparable<V>) valueProvider.apply(a);
                     return comp.compareTo(valueProvider.apply(b));
                 };
-                getState().sortable = true;
+                state.sortable = true;
+            } else if (Number.class.isAssignableFrom(valueType)) {
+                /*
+                 * Value type will be Number whenever using NumberRenderer.
+                 * Provide explicit comparison support in this case even though
+                 * Number itself isn't Comparable.
+                 */
+                comparator = (a, b) -> {
+                    return compareNumbers((Number) valueProvider.apply(a),
+                            (Number) valueProvider.apply(b));
+                };
+                state.sortable = true;
             } else {
-                getState().sortable = false;
+                state.sortable = false;
+            }
+        }
+
+        @SuppressWarnings("unchecked")
+        private static int compareNumbers(Number a, Number b) {
+            assert a.getClass() == b.getClass();
+
+            // Most Number implementations are Comparable
+            if (a instanceof Comparable && a.getClass().isInstance(b)) {
+                return ((Comparable<Number>) a).compareTo(b);
+            } else if (a.equals(b)) {
+                return 0;
+            } else {
+                // Fall back to comparing based on potentially truncated values
+                int compare = Long.compare(a.longValue(), b.longValue());
+                if (compare == 0) {
+                    // This might still produce 0 even though the values are not
+                    // equals, but there's nothing more we can do about that
+                    compare = Double.compare(a.doubleValue(), b.doubleValue());
+                }
+                return compare;
             }
         }
 
         @Override
         public void generateData(T data, JsonObject jsonObject) {
-            assert getState(
-                    false).id != null : "No communication ID set for column "
-                            + getState(false).caption;
+            ColumnState state = getState(false);
+
+            String communicationId = state.id;
+
+            assert communicationId != null : "No communication ID set for column "
+                    + state.caption;
+
+            @SuppressWarnings("unchecked")
+            Renderer<V> renderer = (Renderer<V>) state.renderer;
 
             if (!jsonObject.hasKey(DataCommunicatorConstants.DATA)) {
                 jsonObject.put(DataCommunicatorConstants.DATA,
@@ -355,9 +408,12 @@ public class Grid<T> extends AbstractListing<T, SelectionModel<T>>
             }
             JsonObject obj = jsonObject
                     .getObject(DataCommunicatorConstants.DATA);
-            // Since we dont' have renderers yet, use a dummy toString for
-            // data.
-            obj.put(getState(false).id, valueProvider.apply(data).toString());
+
+            V providerValue = valueProvider.apply(data);
+
+            JsonValue rendererValue = renderer.encode(providerValue);
+
+            obj.put(communicationId, rendererValue);
         }
 
         @Override
@@ -538,23 +594,23 @@ public class Grid<T> extends AbstractListing<T, SelectionModel<T>>
     }
 
     /**
-     * Adds a new column to this {@link Grid} with given header caption and
-     * value provider.
+     * Adds a new column to this {@link Grid} with given header caption,
+     * renderer and value provider.
      *
      * @param caption
      *            the header caption
-     * @param valueType
-     *            the column value class
      * @param valueProvider
      *            the value provider
+     * @param renderer
+     *            the column value class
      * @param <V>
      *            the column value type
      *
      * @return the new column
      */
-    public <V> Column<T, V> addColumn(String caption, Class<V> valueType,
-            Function<T, V> valueProvider) {
-        Column<T, V> c = new Column<>(caption, valueType, valueProvider);
+    public <V> Column<T, V> addColumn(String caption, Function<T, ? extends V> valueProvider,
+            Renderer<V> renderer) {
+        Column<T, V> c = new Column<>(caption, valueProvider, renderer);
 
         c.extend(this);
         c.setId(columnKeys.key(c));
@@ -565,6 +621,22 @@ public class Grid<T> extends AbstractListing<T, SelectionModel<T>>
     }
 
     /**
+     * Adds a new text column to this {@link Grid} with given header caption
+     * string value provider. The column will use a {@link TextRenderer}.
+     *
+     * @param caption
+     *            the header caption
+     * @param valueProvider
+     *            the value provider
+     *
+     * @return the new column
+     */
+    public Column<T, String> addColumn(String caption,
+            Function<T, String> valueProvider) {
+        return addColumn(caption, valueProvider, new TextRenderer());
+    }
+
+    /**
      * Removes the given column from this {@link Grid}.
      *
      * @param column
diff --git a/server/src/main/java/com/vaadin/ui/renderers/AbstractRenderer.java b/server/src/main/java/com/vaadin/ui/renderers/AbstractRenderer.java
new file mode 100644
index 0000000000..4dcf911515
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/renderers/AbstractRenderer.java
@@ -0,0 +1,139 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * 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 com.vaadin.ui.renderers;
+
+import java.util.Objects;
+
+import com.vaadin.server.AbstractClientConnector;
+import com.vaadin.server.AbstractExtension;
+import com.vaadin.server.JsonCodec;
+import com.vaadin.ui.Grid.Column;
+
+import elemental.json.JsonValue;
+
+/**
+ * An abstract base class for server-side
+ * {@link com.vaadin.ui.renderers.Renderer Grid renderers}. This class currently
+ * extends the AbstractExtension superclass, but this fact should be regarded as
+ * an implementation detail and subject to change in a future major or minor
+ * Vaadin version.
+ *
+ * @param <T>
+ *            the type this renderer knows how to present
+ */
+public abstract class AbstractRenderer<T> extends AbstractExtension
+        implements Renderer<T> {
+    private final Class<T> presentationType;
+
+    private final String nullRepresentation;
+
+    /**
+     * Creates a new renderer with the given presentation type and null
+     * representation.
+     *
+     * @param presentationType
+     *            the data type that this renderer displays, not
+     *            <code>null</code>
+     * @param nullRepresentation
+     *            a string that will be sent to the client instead of a regular
+     *            value in case the actual cell value is <code>null</code>. May
+     *            be <code>null</code>.
+     */
+    protected AbstractRenderer(Class<T> presentationType,
+            String nullRepresentation) {
+        Objects.requireNonNull(presentationType,
+                "Presentation type cannot be null");
+        this.presentationType = presentationType;
+        this.nullRepresentation = nullRepresentation;
+    }
+
+    /**
+     * Creates a new renderer with the given presentation type. No null
+     * representation will be used.
+     *
+     * @param presentationType
+     *            the data type that this renderer displays, not
+     *            <code>null</code>
+     */
+    protected AbstractRenderer(Class<T> presentationType) {
+        this(presentationType, null);
+    }
+
+    /**
+     * This method is inherited from AbstractExtension but should never be
+     * called directly with an AbstractRenderer.
+     */
+    @Deprecated
+    @Override
+    @SuppressWarnings("rawtypes")
+    protected Class<Column> getSupportedParentType() {
+        return Column.class;
+    }
+
+    /**
+     * This method is inherited from AbstractExtension but should never be
+     * called directly with an AbstractRenderer.
+     */
+    @Deprecated
+    @Override
+    protected void extend(AbstractClientConnector target) {
+        super.extend(target);
+    }
+
+    @Override
+    public Class<T> getPresentationType() {
+        return presentationType;
+    }
+
+    @Override
+    public JsonValue encode(T value) {
+        if (value == null) {
+            return encode(getNullRepresentation(), String.class);
+        } else {
+            return encode(value, getPresentationType());
+        }
+    }
+
+    /**
+     * Null representation for the renderer
+     *
+     * @return a textual representation of {@code null}
+     */
+    protected String getNullRepresentation() {
+        return nullRepresentation;
+    }
+
+    /**
+     * Encodes the given value to JSON.
+     * <p>
+     * This is a helper method that can be invoked by an {@link #encode(Object)
+     * encode(T)} override if serializing a value of type other than
+     * {@link #getPresentationType() the presentation type} is desired. For
+     * instance, a {@code Renderer<Date>} could first turn a date value into a
+     * formatted string and return {@code encode(dateString, String.class)}.
+     *
+     * @param value
+     *            the value to be encoded
+     * @param type
+     *            the type of the value
+     * @return a JSON representation of the given value
+     */
+    protected <U> JsonValue encode(U value, Class<U> type) {
+        return JsonCodec
+                .encode(value, null, type, getUI().getConnectorTracker())
+                .getEncodedValue();
+    }
+}
\ No newline at end of file
diff --git a/server/src/main/java/com/vaadin/ui/renderers/DateRenderer.java b/server/src/main/java/com/vaadin/ui/renderers/DateRenderer.java
new file mode 100644
index 0000000000..dd33ce064c
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/renderers/DateRenderer.java
@@ -0,0 +1,238 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * 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 com.vaadin.ui.renderers;
+
+import java.text.DateFormat;
+import java.util.Date;
+import java.util.Locale;
+
+import elemental.json.JsonValue;
+
+/**
+ * A renderer for presenting date values.
+ *
+ * @since 7.4
+ * @author Vaadin Ltd
+ */
+public class DateRenderer extends AbstractRenderer<Date> {
+    private final Locale locale;
+    private final String formatString;
+    private final DateFormat dateFormat;
+
+    /**
+     * Creates a new date renderer.
+     * <p>
+     * The renderer is configured to render with the {@link Date#toString()}
+     * representation for the default locale.
+     */
+    public DateRenderer() {
+        this(Locale.getDefault(), "");
+    }
+
+    /**
+     * Creates a new date renderer.
+     * <p>
+     * The renderer is configured to render with the {@link Date#toString()}
+     * representation for the given locale.
+     *
+     * @param locale
+     *            the locale in which to present dates
+     * @throws IllegalArgumentException
+     *             if {@code locale} is {@code null}
+     */
+    public DateRenderer(Locale locale) throws IllegalArgumentException {
+        this("%s", locale, "");
+    }
+
+    /**
+     * Creates a new date renderer.
+     * <p>
+     * The renderer is configured to render with the {@link Date#toString()}
+     * representation for the given locale.
+     *
+     * @param locale
+     *            the locale in which to present dates
+     * @param nullRepresentation
+     *            the textual representation of {@code null} value
+     * @throws IllegalArgumentException
+     *             if {@code locale} is {@code null}
+     */
+    public DateRenderer(Locale locale, String nullRepresentation)
+            throws IllegalArgumentException {
+        this("%s", locale, nullRepresentation);
+    }
+
+    /**
+     * Creates a new date renderer.
+     * <p>
+     * The renderer is configured to render with the given string format, as
+     * displayed in the default locale.
+     *
+     * @param formatString
+     *            the format string with which to format the date
+     * @throws IllegalArgumentException
+     *             if {@code formatString} is {@code null}
+     * @see <a href=
+     *      "http://docs.oracle.com/javase/7/docs/api/java/util/Formatter.html#syntax">Format
+     *      String Syntax</a>
+     */
+    public DateRenderer(String formatString) throws IllegalArgumentException {
+        this(formatString, "");
+    }
+
+    /**
+     * Creates a new date renderer.
+     * <p>
+     * The renderer is configured to render with the given string format, as
+     * displayed in the default locale.
+     *
+     * @param formatString
+     *            the format string with which to format the date
+     * @param nullRepresentation
+     *            the textual representation of {@code null} value
+     * @throws IllegalArgumentException
+     *             if {@code formatString} is {@code null}
+     * @see <a href=
+     *      "http://docs.oracle.com/javase/7/docs/api/java/util/Formatter.html#syntax">Format
+     *      String Syntax</a>
+     */
+    public DateRenderer(String formatString, String nullRepresentation)
+            throws IllegalArgumentException {
+        this(formatString, Locale.getDefault(), nullRepresentation);
+    }
+
+    /**
+     * Creates a new date renderer.
+     * <p>
+     * The renderer is configured to render with the given string format, as
+     * displayed in the given locale.
+     *
+     * @param formatString
+     *            the format string to format the date with
+     * @param locale
+     *            the locale to use
+     * @throws IllegalArgumentException
+     *             if either argument is {@code null}
+     * @see <a href=
+     *      "http://docs.oracle.com/javase/7/docs/api/java/util/Formatter.html#syntax">Format
+     *      String Syntax</a>
+     */
+    public DateRenderer(String formatString, Locale locale)
+            throws IllegalArgumentException {
+        this(formatString, locale, "");
+    }
+
+    /**
+     * Creates a new date renderer.
+     * <p>
+     * The renderer is configured to render with the given string format, as
+     * displayed in the given locale.
+     *
+     * @param formatString
+     *            the format string to format the date with
+     * @param locale
+     *            the locale to use
+     * @param nullRepresentation
+     *            the textual representation of {@code null} value
+     * @throws IllegalArgumentException
+     *             if either argument is {@code null}
+     * @see <a href=
+     *      "http://docs.oracle.com/javase/7/docs/api/java/util/Formatter.html#syntax">Format
+     *      String Syntax</a>
+     */
+    public DateRenderer(String formatString, Locale locale,
+            String nullRepresentation) throws IllegalArgumentException {
+        super(Date.class, nullRepresentation);
+
+        if (formatString == null) {
+            throw new IllegalArgumentException("format string may not be null");
+        }
+
+        if (locale == null) {
+            throw new IllegalArgumentException("locale may not be null");
+        }
+
+        this.locale = locale;
+        this.formatString = formatString;
+        dateFormat = null;
+    }
+
+    /**
+     * Creates a new date renderer.
+     * <p>
+     * The renderer is configured to render with he given date format.
+     *
+     * @param dateFormat
+     *            the date format to use when rendering dates
+     * @throws IllegalArgumentException
+     *             if {@code dateFormat} is {@code null}
+     */
+    public DateRenderer(DateFormat dateFormat) throws IllegalArgumentException {
+        this(dateFormat, "");
+    }
+
+    /**
+     * Creates a new date renderer.
+     * <p>
+     * The renderer is configured to render with he given date format.
+     *
+     * @param dateFormat
+     *            the date format to use when rendering dates
+     * @throws IllegalArgumentException
+     *             if {@code dateFormat} is {@code null}
+     */
+    public DateRenderer(DateFormat dateFormat, String nullRepresentation)
+            throws IllegalArgumentException {
+        super(Date.class, nullRepresentation);
+        if (dateFormat == null) {
+            throw new IllegalArgumentException("date format may not be null");
+        }
+
+        locale = null;
+        formatString = null;
+        this.dateFormat = dateFormat;
+    }
+
+    @Override
+    public String getNullRepresentation() {
+        return super.getNullRepresentation();
+    }
+
+    @Override
+    public JsonValue encode(Date value) {
+        String dateString;
+        if (value == null) {
+            dateString = getNullRepresentation();
+        } else if (dateFormat != null) {
+            dateString = dateFormat.format(value);
+        } else {
+            dateString = String.format(locale, formatString, value);
+        }
+        return encode(dateString, String.class);
+    }
+
+    @Override
+    public String toString() {
+        final String fieldInfo;
+        if (dateFormat != null) {
+            fieldInfo = "dateFormat: " + dateFormat.toString();
+        } else {
+            fieldInfo = "locale: " + locale + ", formatString: " + formatString;
+        }
+
+        return String.format("%s [%s]", getClass().getSimpleName(), fieldInfo);
+    }
+}
diff --git a/server/src/main/java/com/vaadin/ui/renderers/HtmlRenderer.java b/server/src/main/java/com/vaadin/ui/renderers/HtmlRenderer.java
new file mode 100644
index 0000000000..80fcdc18c4
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/renderers/HtmlRenderer.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * 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 com.vaadin.ui.renderers;
+
+/**
+ * A renderer for presenting HTML content.
+ *
+ * @author Vaadin Ltd
+ * @since 7.4
+ */
+public class HtmlRenderer extends AbstractRenderer<String> {
+    /**
+     * Creates a new HTML renderer.
+     *
+     * @param nullRepresentation
+     *            the html representation of {@code null} value
+     */
+    public HtmlRenderer(String nullRepresentation) {
+        super(String.class, nullRepresentation);
+    }
+
+    /**
+     * Creates a new HTML renderer.
+     */
+    public HtmlRenderer() {
+        this("");
+    }
+
+    @Override
+    public String getNullRepresentation() {
+        return super.getNullRepresentation();
+    }
+}
diff --git a/server/src/main/java/com/vaadin/ui/renderers/NumberRenderer.java b/server/src/main/java/com/vaadin/ui/renderers/NumberRenderer.java
new file mode 100644
index 0000000000..02e6ce68fd
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/renderers/NumberRenderer.java
@@ -0,0 +1,205 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * 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 com.vaadin.ui.renderers;
+
+import java.text.NumberFormat;
+import java.util.Locale;
+
+import elemental.json.JsonValue;
+
+/**
+ * A renderer for presenting number values.
+ *
+ * @since 7.4
+ * @author Vaadin Ltd
+ */
+public class NumberRenderer extends AbstractRenderer<Number> {
+    private final Locale locale;
+    private final NumberFormat numberFormat;
+    private final String formatString;
+
+    /**
+     * Creates a new number renderer.
+     * <p/>
+     * The renderer is configured to render with the number's natural string
+     * representation in the default locale.
+     */
+    public NumberRenderer() {
+        this(Locale.getDefault());
+    }
+
+    /**
+     * Creates a new number renderer.
+     * <p/>
+     * The renderer is configured to render the number as defined with the given
+     * number format.
+     *
+     * @param numberFormat
+     *            the number format with which to display numbers
+     * @throws IllegalArgumentException
+     *             if {@code numberFormat} is {@code null}
+     */
+    public NumberRenderer(NumberFormat numberFormat) {
+        this(numberFormat, "");
+    }
+
+    /**
+     * Creates a new number renderer.
+     * <p/>
+     * The renderer is configured to render the number as defined with the given
+     * number format.
+     *
+     * @param numberFormat
+     *            the number format with which to display numbers
+     * @param nullRepresentation
+     *            the textual representation of {@code null} value
+     * @throws IllegalArgumentException
+     *             if {@code numberFormat} is {@code null}
+     */
+    public NumberRenderer(NumberFormat numberFormat, String nullRepresentation)
+            throws IllegalArgumentException {
+        super(Number.class, nullRepresentation);
+
+        if (numberFormat == null) {
+            throw new IllegalArgumentException("Number format may not be null");
+        }
+
+        locale = null;
+        this.numberFormat = numberFormat;
+        formatString = null;
+    }
+
+    /**
+     * Creates a new number renderer.
+     * <p/>
+     * The renderer is configured to render with the number's natural string
+     * representation in the given locale.
+     *
+     * @param locale
+     *            the locale in which to display numbers
+     * @throws IllegalArgumentException
+     *             if {@code locale} is {@code null}
+     */
+    public NumberRenderer(Locale locale) throws IllegalArgumentException {
+        this("%s", locale);
+    }
+
+    /**
+     * Creates a new number renderer.
+     * <p/>
+     * The renderer is configured to render with the number's natural string
+     * representation in the given locale.
+     *
+     * @param formatString
+     *            the format string with which to format the number
+     * @param locale
+     *            the locale in which to display numbers
+     * @throws IllegalArgumentException
+     *             if {@code locale} is {@code null}
+     */
+    public NumberRenderer(String formatString, Locale locale)
+            throws IllegalArgumentException {
+        this(formatString, locale, ""); // This will call #toString() during
+                                        // formatting
+    }
+
+    /**
+     * Creates a new number renderer.
+     * <p/>
+     * The renderer is configured to render with the given format string in the
+     * default locale.
+     *
+     * @param formatString
+     *            the format string with which to format the number
+     * @throws IllegalArgumentException
+     *             if {@code formatString} is {@code null}
+     * @see <a href=
+     *      "http://docs.oracle.com/javase/7/docs/api/java/util/Formatter.html#syntax">Format
+     *      String Syntax</a>
+     */
+    public NumberRenderer(String formatString) throws IllegalArgumentException {
+        this(formatString, Locale.getDefault(), "");
+    }
+
+    /**
+     * Creates a new number renderer.
+     * <p/>
+     * The renderer is configured to render with the given format string in the
+     * given locale.
+     *
+     * @param formatString
+     *            the format string with which to format the number
+     * @param locale
+     *            the locale in which to present numbers
+     * @throws IllegalArgumentException
+     *             if either argument is {@code null}
+     * @see <a href=
+     *      "http://docs.oracle.com/javase/7/docs/api/java/util/Formatter.html#syntax">Format
+     *      String Syntax</a>
+     */
+    public NumberRenderer(String formatString, Locale locale,
+            String nullRepresentation) {
+        super(Number.class, nullRepresentation);
+
+        if (formatString == null) {
+            throw new IllegalArgumentException("Format string may not be null");
+        }
+
+        if (locale == null) {
+            throw new IllegalArgumentException("Locale may not be null");
+        }
+
+        this.locale = locale;
+        numberFormat = null;
+        this.formatString = formatString;
+    }
+
+    @Override
+    public JsonValue encode(Number value) {
+        String stringValue;
+        if (value == null) {
+            stringValue = getNullRepresentation();
+        } else if (formatString != null && locale != null) {
+            stringValue = String.format(locale, formatString, value);
+        } else if (numberFormat != null) {
+            stringValue = numberFormat.format(value);
+        } else {
+            throw new IllegalStateException(String.format(
+                    "Internal bug: " + "%s is in an illegal state: "
+                            + "[locale: %s, numberFormat: %s, formatString: %s]",
+                    getClass().getSimpleName(), locale, numberFormat,
+                    formatString));
+        }
+        return encode(stringValue, String.class);
+    }
+
+    @Override
+    public String toString() {
+        final String fieldInfo;
+        if (numberFormat != null) {
+            fieldInfo = "numberFormat: " + numberFormat.toString();
+        } else {
+            fieldInfo = "locale: " + locale + ", formatString: " + formatString;
+        }
+
+        return String.format("%s [%s]", getClass().getSimpleName(), fieldInfo);
+    }
+
+    @Override
+    public String getNullRepresentation() {
+        return super.getNullRepresentation();
+    }
+}
diff --git a/server/src/main/java/com/vaadin/ui/renderers/ProgressBarRenderer.java b/server/src/main/java/com/vaadin/ui/renderers/ProgressBarRenderer.java
new file mode 100644
index 0000000000..7d05959484
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/renderers/ProgressBarRenderer.java
@@ -0,0 +1,45 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * 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 com.vaadin.ui.renderers;
+
+import elemental.json.JsonValue;
+
+/**
+ * A renderer that represents double values between 0 and 1 as a graphical
+ * progress bar.
+ *
+ * @author Vaadin Ltd
+ * @since 7.4
+ */
+public class ProgressBarRenderer extends AbstractRenderer<Double> {
+
+    /**
+     * Creates a new text renderer
+     */
+    public ProgressBarRenderer() {
+        super(Double.class, null);
+    }
+
+    @Override
+    public JsonValue encode(Double value) {
+        if (value != null) {
+            value = Math.max(Math.min(value, 1), 0);
+        } else {
+            value = 0d;
+        }
+        return super.encode(value);
+    }
+}
diff --git a/server/src/main/java/com/vaadin/ui/renderers/Renderer.java b/server/src/main/java/com/vaadin/ui/renderers/Renderer.java
new file mode 100644
index 0000000000..28582d4e8d
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/renderers/Renderer.java
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * 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 com.vaadin.ui.renderers;
+
+import com.vaadin.server.ClientConnector;
+import com.vaadin.server.Extension;
+
+import elemental.json.JsonValue;
+
+/**
+ * A ClientConnector for controlling client-side
+ * {@link com.vaadin.client.renderers.Renderer Grid renderers}. Renderers
+ * currently extend the Extension interface, but this fact should be regarded as
+ * an implementation detail and subject to change in a future major or minor
+ * Vaadin revision.
+ *
+ * @param <T>
+ *            the type this renderer knows how to present
+ *
+ * @since 7.4
+ * @author Vaadin Ltd
+ */
+public interface Renderer<T> extends Extension {
+
+    /**
+     * Returns the class literal corresponding to the presentation type T.
+     *
+     * @return the class literal of T
+     */
+    Class<T> getPresentationType();
+
+    /**
+     * Encodes the given value into a {@link JsonValue}.
+     *
+     * @param value
+     *            the value to encode
+     * @return a JSON representation of the given value
+     */
+    JsonValue encode(T value);
+
+    /**
+     * This method is inherited from Extension but should never be called
+     * directly with a Renderer.
+     */
+    @Override
+    @Deprecated
+    void remove();
+
+    /**
+     * This method is inherited from Extension but should never be called
+     * directly with a Renderer.
+     */
+    @Override
+    @Deprecated
+    void setParent(ClientConnector parent);
+}
diff --git a/server/src/main/java/com/vaadin/ui/renderers/TextRenderer.java b/server/src/main/java/com/vaadin/ui/renderers/TextRenderer.java
new file mode 100644
index 0000000000..07f09b88f2
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/renderers/TextRenderer.java
@@ -0,0 +1,47 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * 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 com.vaadin.ui.renderers;
+
+/**
+ * A renderer for presenting simple plain-text string values.
+ *
+ * @since 7.4
+ * @author Vaadin Ltd
+ */
+public class TextRenderer extends AbstractRenderer<String> {
+
+    /**
+     * Creates a new text renderer
+     */
+    public TextRenderer() {
+        this("");
+    }
+
+    /**
+     * Creates a new text renderer
+     *
+     * @param nullRepresentation
+     *            the textual representation of {@code null} value
+     */
+    public TextRenderer(String nullRepresentation) {
+        super(String.class, nullRepresentation);
+    }
+
+    @Override
+    public String getNullRepresentation() {
+        return super.getNullRepresentation();
+    }
+}
diff --git a/server/src/test/java/com/vaadin/tests/server/component/grid/GridTest.java b/server/src/test/java/com/vaadin/tests/server/component/grid/GridTest.java
index c426ffe4f6..3dc6dad770 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/grid/GridTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/grid/GridTest.java
@@ -17,7 +17,7 @@ public class GridTest {
     @Before
     public void setUp() {
         grid = new Grid<>();
-        grid.addColumn("foo", String.class, Function.identity());
+        grid.addColumn("foo", Function.identity());
     }
 
     @Test