Moved server files to a server src folder (#9299)

1 files changed, 75 insertions, 0 deletions

diff --git a/server/src/com/vaadin/event/dd/acceptcriteria/AcceptCriterion.java b/server/src/com/vaadin/event/dd/acceptcriteria/AcceptCriterion.java
new file mode 100644
index 0000000000..c0f04d362f
--- /dev/null
+++ b/server/src/com/vaadin/event/dd/acceptcriteria/AcceptCriterion.java
@@ -0,0 +1,75 @@
+/*
+@VaadinApache2LicenseForJavaFiles@
+ */
+/**
+ * 
+ */
+package com.vaadin.event.dd.acceptcriteria;
+
+import java.io.Serializable;
+
+import com.vaadin.event.Transferable;
+import com.vaadin.event.dd.DragAndDropEvent;
+import com.vaadin.event.dd.DropHandler;
+import com.vaadin.terminal.PaintException;
+import com.vaadin.terminal.PaintTarget;
+
+/**
+ * Criterion that can be used create policy to accept/discard dragged content
+ * (presented by {@link Transferable}).
+ * 
+ * The drag and drop mechanism will verify the criteria returned by
+ * {@link DropHandler#getAcceptCriterion()} before calling
+ * {@link DropHandler#drop(DragAndDropEvent)}.
+ * 
+ * The criteria can be evaluated either on the client (browser - see
+ * {@link ClientSideCriterion}) or on the server (see
+ * {@link ServerSideCriterion}). If no constraints are needed, an
+ * {@link AcceptAll} can be used.
+ * 
+ * In addition to accepting or rejecting a possible drop, criteria can provide
+ * additional hints for client side painting.
+ * 
+ * @see DropHandler
+ * @see ClientSideCriterion
+ * @see ServerSideCriterion
+ * 
+ * @since 6.3
+ */
+public interface AcceptCriterion extends Serializable {
+
+    /**
+     * Returns whether the criteria can be checked on the client or whether a
+     * server request is needed to check the criteria.
+     * 
+     * This requirement may depend on the state of the criterion (e.g. logical
+     * operations between criteria), so this cannot be based on a marker
+     * interface.
+     */
+    public boolean isClientSideVerifiable();
+
+    public void paint(PaintTarget target) throws PaintException;
+
+    /**
+     * This needs to be implemented iff criterion does some lazy server side
+     * initialization. The UIDL painted in this method will be passed to client
+     * side drop handler implementation. Implementation can assume that
+     * {@link #accept(DragAndDropEvent)} is called before this method.
+     * 
+     * @param target
+     * @throws PaintException
+     */
+    public void paintResponse(PaintTarget target) throws PaintException;
+
+    /**
+     * Validates the data in event to be appropriate for the
+     * {@link DropHandler#drop(DragAndDropEvent)} method.
+     * <p>
+     * Note that even if your criterion is validated on client side, you should
+     * always validate the data on server side too.
+     * 
+     * @param dragEvent
+     * @return
+     */
+    public boolean accept(DragAndDropEvent dragEvent);
+}
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