vaadin-framework/client/src/main/java/com/vaadin/client/ui/VUpload.java

/*
 * 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.client.ui;

import com.google.gwt.core.client.GWT;
import com.google.gwt.core.client.Scheduler;
import com.google.gwt.core.client.Scheduler.ScheduledCommand;
import com.google.gwt.dom.client.DivElement;
import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.FormElement;
import com.google.gwt.user.client.Command;
import com.google.gwt.user.client.Event;
import com.google.gwt.user.client.Timer;
import com.google.gwt.user.client.ui.FileUpload;
import com.google.gwt.user.client.ui.FlowPanel;
import com.google.gwt.user.client.ui.FormPanel;
import com.google.gwt.user.client.ui.Hidden;
import com.google.gwt.user.client.ui.Panel;
import com.google.gwt.user.client.ui.SimplePanel;
import com.vaadin.client.ApplicationConnection;
import com.vaadin.client.BrowserInfo;
import com.vaadin.client.ConnectorMap;
import com.vaadin.client.StyleConstants;
import com.vaadin.client.VConsole;
import com.vaadin.client.ui.upload.UploadConnector;
import com.vaadin.client.ui.upload.UploadIFrameOnloadStrategy;
import com.vaadin.shared.ui.upload.UploadServerRpc;

/**
 *
 * Note, we are not using GWT FormPanel as we want to listen submitcomplete
 * events even though the upload component is already detached.
 *
 * @author Vaadin Ltd
 *
 */
public class VUpload extends SimplePanel {

    private final class VFileUpload extends FileUpload {
        @Override
        public void onBrowserEvent(Event event) {
            super.onBrowserEvent(event);
            if (event.getTypeInt() == Event.ONCHANGE) {
                if (isImmediateMode() && fu.getFilename() != null
                        && !fu.getFilename().isEmpty()) {
                    submit();
                }
            } else if (BrowserInfo.get().isIE()
                    && event.getTypeInt() == Event.ONFOCUS) {
                // IE and user has clicked on hidden textarea part of upload
                // field. Manually open file selector, other browsers do it by
                // default.
                fireNativeClick(fu.getElement());
                // also remove focus to enable hack if user presses cancel
                // button
                fireNativeBlur(fu.getElement());
            }
        }
    }

    public static final String CLASSNAME = "v-upload";

    /**
     * FileUpload component that opens native OS dialog to select file.
     * <p>
     * For internal use only. May be removed or replaced in the future.
     */
    public FileUpload fu = new VFileUpload();

    Panel panel = new FlowPanel();

    UploadIFrameOnloadStrategy onloadstrategy = GWT
            .create(UploadIFrameOnloadStrategy.class);

    /** For internal use only. May be removed or replaced in the future. */
    public ApplicationConnection client;

    /** For internal use only. May be removed or replaced in the future. */
    public String paintableId;

    /**
     * Button that initiates uploading.
     * <p>
     * For internal use only. May be removed or replaced in the future.
     */
    public final VButton submitButton;

    /**
     * When expecting big files, programmer may initiate some UI changes when
     * uploading the file starts. Bit after submitting file we'll visit the
     * server to check possible changes.
     * <p>
     * For internal use only. May be removed or replaced in the future.
     */
    public Timer t;

    /**
     * some browsers tries to send form twice if submit is called in button
     * click handler, some don't submit at all without it, so we need to track
     * if form is already being submitted
     */
    private boolean submitted = false;

    private boolean enabled = true;

    private boolean immediateMode;

    private Hidden maxfilesize = new Hidden();

    /** For internal use only. May be removed or replaced in the future. */
    public FormElement element;

    private com.google.gwt.dom.client.Element synthesizedFrame;

    /** For internal use only. May be removed or replaced in the future. */
    public int nextUploadId;

    public VUpload() {
        super(com.google.gwt.dom.client.Document.get().createFormElement());

        element = getElement().cast();
        setEncoding(getElement(), FormPanel.ENCODING_MULTIPART);
        element.setMethod(FormPanel.METHOD_POST);

        setWidget(panel);
        panel.add(maxfilesize);
        panel.add(fu);
        submitButton = new VButton();
        submitButton.addClickHandler(event -> {
            if (isImmediateMode()) {
                // fire click on upload (e.g. focused button and hit space)
                fireNativeClick(fu.getElement());
            } else {
                submit();
            }
        });
        panel.add(submitButton);

        setStyleName(CLASSNAME);
    }

    private static native void setEncoding(Element form, String encoding)
    /*-{
      form.enctype = encoding;
    }-*/;

    /**
     * Sets the upload in immediate mode.
     *
     * @param immediateMode
     *            {@code true} for immediate mode, {@code false} for
     *            non-immediate mode
     */
    public void setImmediateMode(boolean immediateMode) {
        if (this.immediateMode != immediateMode) {
            this.immediateMode = immediateMode;
            if (immediateMode) {
                fu.sinkEvents(Event.ONCHANGE);
                fu.sinkEvents(Event.ONFOCUS);
            } else {
                fu.unsinkEvents(Event.ONCHANGE);
                fu.unsinkEvents(Event.ONFOCUS);
            }
        }
        setStyleName(getElement(), CLASSNAME + "-immediate", immediateMode);
    }

    /**
     * Returns whether this component is in immediate mode or not.
     *
     * @return {@code true} for immediate mode, {@code false} for not
     */
    public boolean isImmediateMode() {
        return immediateMode;
    }

    private static native void fireNativeClick(Element element)
    /*-{
        element.click();
    }-*/;

    private static native void fireNativeBlur(Element element)
    /*-{
        element.blur();
    }-*/;

    /** For internal use only. May be removed or replaced in the future. */
    public void disableUpload() {
        setEnabledForSubmitButton(false);
        if (!submitted) {
            // Cannot disable the fileupload while submitting or the file won't
            // be submitted at all
            fu.getElement().setPropertyBoolean("disabled", true);
        }
        enabled = false;
    }

    /** For internal use only. May be removed or replaced in the future. */
    public void enableUpload() {
        setEnabledForSubmitButton(true);
        fu.getElement().setPropertyBoolean("disabled", false);
        enabled = true;
        if (submitted) {
            /*
             * An old request is still in progress (most likely cancelled),
             * ditching that target frame to make it possible to send a new
             * file. A new target frame is created later."
             */
            cleanTargetFrame();
            submitted = false;
        }
    }

    private void setEnabledForSubmitButton(boolean enabled) {
        submitButton.setEnabled(enabled);
        submitButton.setStyleName(StyleConstants.DISABLED, !enabled);
    }

    /**
     * Re-creates file input field and populates panel. This is needed as we
     * want to clear existing values from our current file input field.
     */
    private void rebuildPanel() {
        panel.remove(submitButton);
        panel.remove(fu);
        fu = new VFileUpload();
        fu.setName(paintableId + "_file");
        fu.getElement().setPropertyBoolean("disabled", !enabled);
        panel.add(fu);
        panel.add(submitButton);
        if (isImmediateMode()) {
            fu.sinkEvents(Event.ONCHANGE);
        }
    }

    /**
     * Called by JSNI (hooked via {@link #onloadstrategy})
     */
    private void onSubmitComplete() {
        /* Needs to be run dereferred to avoid various browser issues. */
        Scheduler.get().scheduleDeferred(new Command() {
            @Override
            public void execute() {
                if (submitted) {
                    if (client != null) {
                        if (t != null) {
                            t.cancel();
                        }
                        VConsole.log("VUpload:Submit complete");
                        if (isAttached()) {
                            // no need to call poll() if component is already
                            // detached #8728
                            ((UploadConnector) ConnectorMap.get(client)
                                    .getConnector(VUpload.this))
                                            .getRpcProxy(UploadServerRpc.class)
                                            .poll();
                        }
                    }

                    rebuildPanel();

                    submitted = false;
                    enableUpload();
                    if (!isAttached()) {
                        /*
                         * Upload is complete when upload is already abandoned.
                         */
                        cleanTargetFrame();
                    }
                }
            }
        });
    }

    ScheduledCommand startUploadCmd = () -> {
        element.submit();
        submitted = true;

        disableUpload();

        /*
         * Visit server a moment after upload has started to see possible
         * changes from UploadStarted event. Will be cleared on complete.
         *
         * Must get the id here as the upload can finish before the timer
         * expires and in that case nextUploadId has been updated and is wrong.
         */
        final int thisUploadId = nextUploadId;
        t = new Timer() {
            @Override
            public void run() {
                // Only visit the server if the upload has not already
                // finished
                if (thisUploadId == nextUploadId) {
                    VConsole.log(
                            "Visiting server to see if upload started event changed UI.");
                    client.updateVariable(paintableId, "pollForStart",
                            thisUploadId, true);
                }
            }
        };
        t.schedule(800);
    };

    /** For internal use only. May be removed or replaced in the future. */
    public void submit() {
        if (submitted || !enabled) {
            VConsole.log("Submit cancelled (disabled or already submitted)");
            return;
        }
        if (fu.getFilename().isEmpty()) {
            VConsole.log("Submitting empty selection (no file)");
        }
        // flush possibly pending variable changes, so they will be handled
        // before upload
        client.sendPendingVariableChanges();

        // This is done as deferred because sendPendingVariableChanges is also
        // deferred and we want to start the upload only after the changes have
        // been sent to the server
        Scheduler.get().scheduleDeferred(startUploadCmd);
    }

    /** For internal use only. May be removed or replaced in the future. */
    public void disableTitle(boolean disable) {
        if (disable) {
            // Disable title attribute for upload element.
            if (BrowserInfo.get().isChrome()) {
                // In Chrome title has to be set to " " to make it invisible
                fu.setTitle(" ");
            } else if (BrowserInfo.get().isFirefox()) {
                // In FF title has to be set to empty string to make it
                // invisible
                // Method setTitle removes title attribute when it's an empty
                // string, so setAttribute() should be used here
                fu.getElement().setAttribute("title", "");
            }
            // For other browsers absent title doesn't show default tooltip for
            // input element
        } else {
            fu.setTitle(null);
        }
    }

    @Override
    protected void onAttach() {
        super.onAttach();
        if (client != null) {
            ensureTargetFrame();
        }
    }

    /** For internal use only. May be removed or replaced in the future. */
    public void ensureTargetFrame() {
        if (synthesizedFrame == null) {
            // Attach a hidden IFrame to the form. This is the target iframe to
            // which the form will be submitted. We have to create the iframe
            // using innerHTML, because setting an iframe's 'name' property
            // dynamically doesn't work on most browsers.
            DivElement dummy = Document.get().createDivElement();
            dummy.setInnerHTML("<iframe src=\"javascript:''\" name='"
                    + getFrameName()
                    + "' style='position:absolute;width:0;height:0;border:0'>");
            synthesizedFrame = dummy.getFirstChildElement();
            Document.get().getBody().appendChild(synthesizedFrame);
            element.setTarget(getFrameName());
            onloadstrategy.hookEvents(synthesizedFrame, this);
        }
    }

    private String getFrameName() {
        return paintableId + "_TGT_FRAME";
    }

    @Override
    protected void onDetach() {
        super.onDetach();
        if (!submitted) {
            cleanTargetFrame();
        }
    }

    private void cleanTargetFrame() {
        if (synthesizedFrame != null) {
            Document.get().getBody().removeChild(synthesizedFrame);
            onloadstrategy.unHookEvents(synthesizedFrame);
            synthesizedFrame = null;
        }
    }

}