com.google.appinventor.client.editor.simple.palette.SimplePaletteItem.java Source code

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Here is the source code for com.google.appinventor.client.editor.simple.palette.SimplePaletteItem.java

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// -*- mode: java; c-basic-offset: 2; -*-
// Copyright 2009-2011 Google, All Rights reserved
// Copyright 2011-2012 MIT, All rights reserved
// Released under the Apache License, Version 2.0
// http://www.apache.org/licenses/LICENSE-2.0

package com.google.appinventor.client.editor.simple.palette;

import com.google.appinventor.client.TranslationDesignerPallete;
import com.google.appinventor.client.editor.simple.components.MockComponent;
import com.google.appinventor.client.editor.simple.components.MockComponentsUtil;
import com.google.appinventor.client.widgets.dnd.DragSourcePanel;
import com.google.appinventor.client.widgets.dnd.DragSourceSupport;
import com.google.appinventor.client.widgets.dnd.DropTarget;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Image;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.Widget;

/**
 * This class represents a component on the component palette panel.
 *
 */
public class SimplePaletteItem extends DragSourcePanel {
    // Queried to determine the set of UI elements that accept drops of palette items
    private DropTargetProvider dropTargetProvider;

    // Component descriptor (needed for mock component instantiation)
    private SimpleComponentDescriptor scd;

    // Cached prototype of the component that this palette item creates.
    // Properties of the prototype may be queried by accessors.
    private MockComponent componentPrototype;

    /**
     * Creates a new palette item.
     *
     * @param scd  component descriptor for palette item
     * @param dropTargetProvider  provider of targets that palette items can be dropped on
     */
    public SimplePaletteItem(SimpleComponentDescriptor scd, DropTargetProvider dropTargetProvider) {
        this.dropTargetProvider = dropTargetProvider;
        this.scd = scd;

        componentPrototype = null;

        // Initialize palette item UI
        HorizontalPanel panel = new HorizontalPanel();
        panel.setStylePrimaryName("ode-SimplePaletteItem");

        Image image = scd.getImage();
        image.setStylePrimaryName("ode-SimplePaletteItem-icon");
        panel.add(image);
        panel.setCellHorizontalAlignment(image, HorizontalPanel.ALIGN_LEFT);
        panel.setCellWidth(image, "30px");

        Label label = new Label(TranslationDesignerPallete.getCorrespondingString(scd.getName()));
        label.setHorizontalAlignment(Label.ALIGN_LEFT);
        label.addStyleName("ode-SimplePaletteItem-caption");
        panel.add(label);

        HorizontalPanel optPanel = new HorizontalPanel();

        ComponentHelpWidget helpImage = new ComponentHelpWidget(scd);
        helpImage.addStyleName("ode-SimplePalleteItem-button");
        optPanel.add(helpImage);
        optPanel.setCellHorizontalAlignment(helpImage, HorizontalPanel.ALIGN_LEFT);

        if (scd.getExternal()) {
            ComponentRemoveWidget deleteImage = new ComponentRemoveWidget(scd);
            deleteImage.addStyleName("ode-SimplePalleteItem-button");
            optPanel.add(deleteImage);
            optPanel.setCellHorizontalAlignment(deleteImage, HorizontalPanel.ALIGN_RIGHT);
        }

        panel.add(optPanel);
        panel.setCellHorizontalAlignment(optPanel, HorizontalPanel.ALIGN_RIGHT);

        panel.setWidth("100%");
        add(panel);
        setWidth("100%");
    }

    /**
     * Returns a new mock component for the palette item.
     * <p>
     * The caller is assumed to take ownership of the returned component.
     *
     * @return  mock component
     */
    public MockComponent createMockComponent() {
        cacheInternalComponentPrototype();

        MockComponent returnedComponentPrototype = componentPrototype;
        componentPrototype = null;
        return returnedComponentPrototype;
    }

    /**
     * Returns whether this palette item creates components with a
     * visual representation.
     */
    public boolean isVisibleComponent() {
        cacheInternalComponentPrototype();
        return componentPrototype.isVisibleComponent();
    }

    private void cacheInternalComponentPrototype() {
        if (componentPrototype == null) {
            componentPrototype = scd.createMockComponentFromPalette();
        }
    }

    // DragSource implementation

    @Override
    public void onDragStart() {
        // no action
    }

    @Override
    public Widget createDragWidget(int x, int y) {
        MockComponent component = createMockComponent();
        // Some components override getPreferredWidth/Height because getOffsetWidth/Height (which is
        // what MockComponentsUtil.getPreferredSizeOfDetachedWidget uses) returns very inaccurate
        // values. These components can give us the width/height even when the component is not
        // attached.
        int width = component.getPreferredWidth();
        int height = component.getPreferredHeight();
        if (width <= 0 && height <= 0) {
            // Other components don't override getPreferredWidth/Height, which means that we'll get 0 (or
            // less) because the component is not attached. So, we use getPreferredSizeOfDetachedWidget.
            int[] size = MockComponentsUtil.getPreferredSizeOfDetachedWidget(component);
            width = size[0];
            height = size[1];
        }
        component.setPixelSize(width, height);
        DragSourceSupport.configureDragWidgetToAppearWithCursorAt(component, width / 2, height / 2);
        return component;
    }

    @Override
    public Widget getDragWidget() {
        return dragSourceSupport.getDragWidget();
    }

    @Override
    public DropTarget[] getDropTargets() {
        return dropTargetProvider.getDropTargets();
    }

    @Override
    public void onDragEnd() {
        // no action
    }

    // Utility methods

    public String getName() {
        return scd.getName();
    }
}