layout/gle2/LayoutActionBar.java

/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Eclipse Public License, Version 1.0 (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.eclipse.org/org/documents/epl-v10.php
 *
 * 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.android.ide.eclipse.adt.internal.editors.layout.gle2;

import static com.android.SdkConstants.ANDROID_URI;
import static com.android.SdkConstants.ATTR_ID;

import com.android.annotations.NonNull;
import com.android.ide.common.api.INode;
import com.android.ide.common.api.RuleAction;
import com.android.ide.common.api.RuleAction.Choices;
import com.android.ide.common.api.RuleAction.Separator;
import com.android.ide.common.api.RuleAction.Toggle;
import com.android.ide.common.layout.BaseViewRule;
import com.android.ide.eclipse.adt.internal.editors.IconFactory;
import com.android.ide.eclipse.adt.internal.editors.common.CommonXmlEditor;
import com.android.ide.eclipse.adt.internal.editors.layout.configuration.Configuration;
import com.android.ide.eclipse.adt.internal.editors.layout.configuration.ConfigurationChooser;
import com.android.ide.eclipse.adt.internal.editors.layout.gre.NodeProxy;
import com.android.ide.eclipse.adt.internal.editors.layout.gre.RulesEngine;
import com.android.ide.eclipse.adt.internal.lint.EclipseLintClient;
import com.android.ide.eclipse.adt.internal.preferences.AdtPrefs;
import com.android.sdklib.devices.Device;
import com.android.sdklib.devices.Screen;
import com.android.sdkuilib.internal.widgets.ResolutionChooserDialog;
import com.google.common.base.Strings;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IMarker;
import org.eclipse.jface.window.Window;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.swt.widgets.MenuItem;
import org.eclipse.swt.widgets.ToolBar;
import org.eclipse.swt.widgets.ToolItem;
import org.eclipse.ui.ISharedImages;
import org.eclipse.ui.PlatformUI;

import java.net.URL;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * Toolbar shown at the top of the layout editor, which adds a number of context-sensitive
 * layout actions (as well as zooming controls on the right).
 */
public class LayoutActionBar extends Composite {
    private GraphicalEditorPart mEditor;
    private ToolBar mLayoutToolBar;
    private ToolBar mLintToolBar;
    private ToolBar mZoomToolBar;
    private ToolItem mZoomRealSizeButton;
    private ToolItem mZoomOutButton;
    private ToolItem mZoomResetButton;
    private ToolItem mZoomInButton;
    private ToolItem mZoomFitButton;
    private ToolItem mLintButton;
    private List<RuleAction> mPrevActions;

    /**
     * Creates a new {@link LayoutActionBar} and adds it to the given parent.
     *
     * @param parent the parent composite to add the actions bar to
     * @param style the SWT style to apply
     * @param editor the associated layout editor
     */
    public LayoutActionBar(Composite parent, int style, GraphicalEditorPart editor) {
        super(parent, style | SWT.NO_FOCUS);
        mEditor = editor;

        GridLayout layout = new GridLayout(3, false);
        setLayout(layout);

        mLayoutToolBar = new ToolBar(this, /*SWT.WRAP |*/ SWT.FLAT | SWT.RIGHT | SWT.HORIZONTAL);
        mLayoutToolBar.setLayoutData(new GridData(SWT.FILL, SWT.BEGINNING, true, false));
        mZoomToolBar = createZoomControls();
        mZoomToolBar.setLayoutData(new GridData(SWT.END, SWT.BEGINNING, false, false));
        mLintToolBar = createLintControls();

        GridData lintData = new GridData(SWT.END, SWT.BEGINNING, false, false);
        lintData.exclude = true;
        mLintToolBar.setLayoutData(lintData);
    }

    @Override
    public void dispose() {
        super.dispose();
        mPrevActions = null;
    }

    /** Updates the layout contents based on the current selection */
    void updateSelection() {
        NodeProxy parent = null;
        LayoutCanvas canvas = mEditor.getCanvasControl();
        SelectionManager selectionManager = canvas.getSelectionManager();
        List<SelectionItem> selections = selectionManager.getSelections();
        if (selections.size() > 0) {
            // TODO: better handle multi-selection -- maybe we should disable it or
            // something.
            // What if you select children with different parents? Of different types?
            // etc.
            NodeProxy node = selections.get(0).getNode();
            if (node != null && node.getParent() != null) {
                parent = (NodeProxy) node.getParent();
            }
        }

        if (parent == null) {
            // Show the background's properties
            CanvasViewInfo root = canvas.getViewHierarchy().getRoot();
            if (root == null) {
                return;
            }
            parent = canvas.getNodeFactory().create(root);
            selections = Collections.emptyList();
        }

        RulesEngine engine = mEditor.getRulesEngine();
        List<NodeProxy> selectedNodes = new ArrayList<NodeProxy>();
        for (SelectionItem item : selections) {
            selectedNodes.add(item.getNode());
        }
        List<RuleAction> actions = new ArrayList<RuleAction>();
        engine.callAddLayoutActions(actions, parent, selectedNodes);

        // Place actions in the correct order (the actions may come from different
        // rules and should be merged properly via sorting keys)
        Collections.sort(actions);

        // Add in actions for the child as well, if there is exactly one.
        // These are not merged into the parent list of actions; they are appended
        // at the end.
        int index = -1;
        String label = null;
        if (selectedNodes.size() == 1) {
            List<RuleAction> itemActions = new ArrayList<RuleAction>();
            NodeProxy selectedNode = selectedNodes.get(0);
            engine.callAddLayoutActions(itemActions, selectedNode, null);
            if (itemActions.size() > 0) {
                Collections.sort(itemActions);

                if (!(itemActions.get(0) instanceof RuleAction.Separator)) {
                    actions.add(RuleAction.createSeparator(0));
                }
                label = selectedNode.getStringAttr(ANDROID_URI, ATTR_ID);
                if (label != null) {
                    label = BaseViewRule.stripIdPrefix(label);
                    index = actions.size();
                }
                actions.addAll(itemActions);
            }
        }

        if (!updateActions(actions)) {
            updateToolbar(actions, index, label);
        }
        mPrevActions = actions;
    }

    /** Update the toolbar widgets */
    private void updateToolbar(final List<RuleAction> actions, final int labelIndex,
            final String label) {
        if (mLayoutToolBar == null || mLayoutToolBar.isDisposed()) {
            return;
        }
        for (ToolItem c : mLayoutToolBar.getItems()) {
            c.dispose();
        }
        mLayoutToolBar.pack();
        addActions(actions, labelIndex, label);
        mLayoutToolBar.pack();
        mLayoutToolBar.layout();
    }

    /**
     * Attempts to update the existing toolbar actions, if the action list is
     * similar to the current list. Returns false if this cannot be done and the
     * contents must be replaced.
     */
    private boolean updateActions(@NonNull List<RuleAction> actions) {
        List<RuleAction> before = mPrevActions;
        List<RuleAction> after = actions;

        if (before == null) {
            return false;
        }

        if (!before.equals(after) || after.size() > mLayoutToolBar.getItemCount()) {
            return false;
        }

        int actionIndex = 0;
        for (int i = 0, max = mLayoutToolBar.getItemCount(); i < max; i++) {
            ToolItem item = mLayoutToolBar.getItem(i);
            int style = item.getStyle();
            Object data = item.getData();
            if (data != null) {
                // One action can result in multiple toolbar items (e.g. a choice action
                // can result in multiple radio buttons), so we've have to replace all of
                // them with the corresponding new action
                RuleAction prevAction = before.get(actionIndex);
                while (prevAction != data) {
                    actionIndex++;
                    if (actionIndex == before.size()) {
                        return false;
                    }
                    prevAction = before.get(actionIndex);
                    if (prevAction == data) {
                        break;
                    } else if (!(prevAction instanceof RuleAction.Separator)) {
                        return false;
                    }
                }
                RuleAction newAction = after.get(actionIndex);
                assert newAction.equals(prevAction); // Maybe I can do this lazily instead?

                // Update action binding to the new action
                item.setData(newAction);

                // Sync button states: the checked state is not considered part of
                // RuleAction equality
                if ((style & SWT.CHECK) != 0) {
                    assert newAction instanceof Toggle;
                    Toggle toggle = (Toggle) newAction;
                    item.setSelection(toggle.isChecked());
                } else if ((style & SWT.RADIO) != 0) {
                    assert newAction instanceof Choices;
                    Choices choices = (Choices) newAction;
                    String current = choices.getCurrent();
                    String id = (String) item.getData(ATTR_ID);
                    boolean selected = Strings.nullToEmpty(current).equals(id);
                    item.setSelection(selected);
                }
            } else {
                // Must be a separator, or a label (which we insert for nested widgets)
                assert (style & SWT.SEPARATOR) != 0 || !item.getText().isEmpty() : item;
            }
        }

        return true;
    }

    private void addActions(List<RuleAction> actions, int labelIndex, String label) {
        if (actions.size() > 0) {
            // Flag used to indicate that if there are any actions -after- this, it
            // should be separated from this current action (we don't unconditionally
            // add a separator at the end of these groups in case there are no more
            // actions at the end so that we don't have a trailing separator)
            boolean needSeparator = false;

            int index = 0;
            for (RuleAction action : actions) {
                if (index == labelIndex) {
                    final ToolItem button = new ToolItem(mLayoutToolBar, SWT.PUSH);
                    button.setText(label);
                    needSeparator = false;
                }
                index++;

                if (action instanceof Separator) {
                    addSeparator(mLayoutToolBar);
                    needSeparator = false;
                    continue;
                } else if (needSeparator) {
                    addSeparator(mLayoutToolBar);
                    needSeparator = false;
                }

                if (action instanceof RuleAction.Choices) {
                    RuleAction.Choices choices = (Choices) action;
                    if (!choices.isRadio()) {
                        addDropdown(choices);
                    } else {
                        addSeparator(mLayoutToolBar);
                        addRadio(choices);
                        needSeparator = true;
                    }
                } else if (action instanceof RuleAction.Toggle) {
                    addToggle((Toggle) action);
                } else {
                    addPlainAction(action);
                }
            }
        }
    }

    /** Add a separator to the toolbar, unless there already is one there at the end already */
    private static void addSeparator(ToolBar toolBar) {
        int n = toolBar.getItemCount();
        if (n > 0 && (toolBar.getItem(n - 1).getStyle() & SWT.SEPARATOR) == 0) {
            ToolItem separator = new ToolItem(toolBar, SWT.SEPARATOR);
            separator.setWidth(15);
        }
    }

    private void addToggle(Toggle toggle) {
        final ToolItem button = new ToolItem(mLayoutToolBar, SWT.CHECK);

        URL iconUrl = toggle.getIconUrl();
        String title = toggle.getTitle();
        if (iconUrl != null) {
            button.setImage(IconFactory.getInstance().getIcon(iconUrl));
            button.setToolTipText(title);
        } else {
            button.setText(title);
        }
        button.setData(toggle);

        button.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                Toggle toggle = (Toggle) button.getData();
                toggle.getCallback().action(toggle, getSelectedNodes(),
                        toggle.getId(), button.getSelection());
                updateSelection();
            }
        });
        if (toggle.isChecked()) {
            button.setSelection(true);
        }
    }

    private List<INode> getSelectedNodes() {
        List<SelectionItem> selections =
                mEditor.getCanvasControl().getSelectionManager().getSelections();
        List<INode> nodes = new ArrayList<INode>(selections.size());
        for (SelectionItem item : selections) {
            nodes.add(item.getNode());
        }

        return nodes;
    }


    private void addPlainAction(RuleAction menuAction) {
        final ToolItem button = new ToolItem(mLayoutToolBar, SWT.PUSH);

        URL iconUrl = menuAction.getIconUrl();
        String title = menuAction.getTitle();
        if (iconUrl != null) {
            button.setImage(IconFactory.getInstance().getIcon(iconUrl));
            button.setToolTipText(title);
        } else {
            button.setText(title);
        }
        button.setData(menuAction);

        button.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                RuleAction menuAction = (RuleAction) button.getData();
                menuAction.getCallback().action(menuAction, getSelectedNodes(), menuAction.getId(),
                        false);
                updateSelection();
            }
        });
    }

    private void addRadio(RuleAction.Choices choices) {
        List<URL> icons = choices.getIconUrls();
        List<String> titles = choices.getTitles();
        List<String> ids = choices.getIds();
        String current = choices.getCurrent() != null ? choices.getCurrent() : ""; //$NON-NLS-1$

        assert icons != null;
        assert icons.size() == titles.size();

        for (int i = 0; i < icons.size(); i++) {
            URL iconUrl = icons.get(i);
            String title = titles.get(i);
            final String id = ids.get(i);
            final ToolItem item = new ToolItem(mLayoutToolBar, SWT.RADIO);
            item.setToolTipText(title);
            item.setImage(IconFactory.getInstance().getIcon(iconUrl));
            item.setData(choices);
            item.setData(ATTR_ID, id);
            item.addSelectionListener(new SelectionAdapter() {
                @Override
                public void widgetSelected(SelectionEvent e) {
                    if (item.getSelection()) {
                        RuleAction.Choices choices = (Choices) item.getData();
                        choices.getCallback().action(choices, getSelectedNodes(), id, null);
                        updateSelection();
                    }
                }
            });
            boolean selected = current.equals(id);
            if (selected) {
                item.setSelection(true);
            }
        }
    }

    private void addDropdown(RuleAction.Choices choices) {
        final ToolItem combo = new ToolItem(mLayoutToolBar, SWT.DROP_DOWN);
        URL iconUrl = choices.getIconUrl();
        if (iconUrl != null) {
            combo.setImage(IconFactory.getInstance().getIcon(iconUrl));
            combo.setToolTipText(choices.getTitle());
        } else {
            combo.setText(choices.getTitle());
        }
        combo.setData(choices);

        Listener menuListener = new Listener() {
            @Override
            public void handleEvent(Event event) {
                Menu menu = new Menu(mLayoutToolBar.getShell(), SWT.POP_UP);
                RuleAction.Choices choices = (Choices) combo.getData();
                List<URL> icons = choices.getIconUrls();
                List<String> titles = choices.getTitles();
                List<String> ids = choices.getIds();
                String current = choices.getCurrent() != null ? choices.getCurrent() : ""; //$NON-NLS-1$

                for (int i = 0; i < titles.size(); i++) {
                    String title = titles.get(i);
                    final String id = ids.get(i);
                    URL itemIconUrl = icons != null && icons.size() > 0 ? icons.get(i) : null;
                    MenuItem item = new MenuItem(menu, SWT.CHECK);
                    item.setText(title);
                    if (itemIconUrl != null) {
                        Image itemIcon = IconFactory.getInstance().getIcon(itemIconUrl);
                        item.setImage(itemIcon);
                    }

                    boolean selected = id.equals(current);
                    if (selected) {
                        item.setSelection(true);
                    }

                    item.addSelectionListener(new SelectionAdapter() {
                        @Override
                        public void widgetSelected(SelectionEvent e) {
                            RuleAction.Choices choices = (Choices) combo.getData();
                            choices.getCallback().action(choices, getSelectedNodes(), id, null);
                            updateSelection();
                        }
                    });
                }

                Rectangle bounds = combo.getBounds();
                Point location = new Point(bounds.x, bounds.y + bounds.height);
                location = combo.getParent().toDisplay(location);
                menu.setLocation(location.x, location.y);
                menu.setVisible(true);
            }
        };
        combo.addListener(SWT.Selection, menuListener);
    }

    // ---- Zoom Controls ----

    @SuppressWarnings("unused") // SWT constructors have side effects, they are not unused
    private ToolBar createZoomControls() {
        ToolBar toolBar = new ToolBar(this, SWT.FLAT | SWT.RIGHT | SWT.HORIZONTAL);

        IconFactory iconFactory = IconFactory.getInstance();
        mZoomRealSizeButton = new ToolItem(toolBar, SWT.CHECK);
        mZoomRealSizeButton.setToolTipText("Emulate Real Size");
        mZoomRealSizeButton.setImage(iconFactory.getIcon("zoomreal")); //$NON-NLS-1$);
        mZoomRealSizeButton.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                boolean newState = mZoomRealSizeButton.getSelection();
                if (rescaleToReal(newState)) {
                    mZoomOutButton.setEnabled(!newState);
                    mZoomResetButton.setEnabled(!newState);
                    mZoomInButton.setEnabled(!newState);
                    mZoomFitButton.setEnabled(!newState);
                } else {
                    mZoomRealSizeButton.setSelection(!newState);
                }
            }
        });

        mZoomFitButton = new ToolItem(toolBar, SWT.PUSH);
        mZoomFitButton.setToolTipText("Zoom to Fit (0)");
        mZoomFitButton.setImage(iconFactory.getIcon("zoomfit")); //$NON-NLS-1$);
        mZoomFitButton.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                rescaleToFit(true);
            }
        });

        mZoomResetButton = new ToolItem(toolBar, SWT.PUSH);
        mZoomResetButton.setToolTipText("Reset Zoom to 100% (1)");
        mZoomResetButton.setImage(iconFactory.getIcon("zoom100")); //$NON-NLS-1$);
        mZoomResetButton.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                resetScale();
            }
        });

        // Group zoom in/out separately
        new ToolItem(toolBar, SWT.SEPARATOR);

        mZoomOutButton = new ToolItem(toolBar, SWT.PUSH);
        mZoomOutButton.setToolTipText("Zoom Out (-)");
        mZoomOutButton.setImage(iconFactory.getIcon("zoomminus")); //$NON-NLS-1$);
        mZoomOutButton.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                rescale(-1);
            }
        });

        mZoomInButton = new ToolItem(toolBar, SWT.PUSH);
        mZoomInButton.setToolTipText("Zoom In (+)");
        mZoomInButton.setImage(iconFactory.getIcon("zoomplus")); //$NON-NLS-1$);
        mZoomInButton.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                rescale(+1);
            }
        });

        return toolBar;
    }

    @SuppressWarnings("unused") // SWT constructors have side effects, they are not unused
    private ToolBar createLintControls() {
        ToolBar toolBar = new ToolBar(this, SWT.FLAT | SWT.RIGHT | SWT.HORIZONTAL);

        // Separate from adjacent toolbar
        new ToolItem(toolBar, SWT.SEPARATOR);

        ISharedImages sharedImages = PlatformUI.getWorkbench().getSharedImages();
        mLintButton = new ToolItem(toolBar, SWT.PUSH);
        mLintButton.setToolTipText("Show Lint Warnings for this Layout");
        mLintButton.setImage(sharedImages.getImage(ISharedImages.IMG_OBJS_WARN_TSK));
        mLintButton.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                CommonXmlEditor editor = mEditor.getEditorDelegate().getEditor();
                IFile file = editor.getInputFile();
                if (file != null) {
                    EclipseLintClient.showErrors(getShell(), file, editor);
                }
            }
        });

        return toolBar;
    }

    /**
     * Updates the lint indicator state in the given layout editor
     */
    public void updateErrorIndicator() {
        updateErrorIndicator(mEditor.getEditedFile());
    }

    /**
     * Updates the lint indicator state for the given file
     *
     * @param file the file to show the indicator status for
     */
    public void updateErrorIndicator(IFile file) {
        IMarker[] markers = EclipseLintClient.getMarkers(file);
        updateErrorIndicator(markers.length);
    }

    /**
     * Sets whether the action bar should show the "lint warnings" button
     *
     * @param hasLintWarnings whether there are lint errors to be shown
     */
    private void updateErrorIndicator(final int markerCount) {
        Display display = getDisplay();
        if (display.getThread() != Thread.currentThread()) {
            display.asyncExec(new Runnable() {
                @Override
                public void run() {
                    if (!isDisposed()) {
                        updateErrorIndicator(markerCount);
                    }
                }
            });
            return;
        }

        GridData layoutData = (GridData) mLintToolBar.getLayoutData();
        Integer existing = (Integer) mLintToolBar.getData();
        Integer current = Integer.valueOf(markerCount);
        if (!current.equals(existing)) {
            mLintToolBar.setData(current);
            boolean layout = false;
            boolean hasLintWarnings = markerCount > 0 && AdtPrefs.getPrefs().isLintOnSave();
            if (layoutData.exclude == hasLintWarnings) {
                layoutData.exclude = !hasLintWarnings;
                mLintToolBar.setVisible(hasLintWarnings);
                layout = true;
            }
            if (markerCount > 0) {
                String iconName = "";
                switch (markerCount) {
                    case 1: iconName = "lint1"; break;  //$NON-NLS-1$
                    case 2: iconName = "lint2"; break;  //$NON-NLS-1$
                    case 3: iconName = "lint3"; break;  //$NON-NLS-1$
                    case 4: iconName = "lint4"; break;  //$NON-NLS-1$
                    case 5: iconName = "lint5"; break;  //$NON-NLS-1$
                    case 6: iconName = "lint6"; break;  //$NON-NLS-1$
                    case 7: iconName = "lint7"; break;  //$NON-NLS-1$
                    case 8: iconName = "lint8"; break;  //$NON-NLS-1$
                    case 9: iconName = "lint9"; break;  //$NON-NLS-1$
                    default: iconName = "lint9p"; break;//$NON-NLS-1$
                }
                mLintButton.setImage(IconFactory.getInstance().getIcon(iconName));
            }
            if (layout) {
                layout();
            }
            redraw();
        }
    }

    /**
     * Returns true if zooming in/out/to-fit/etc is allowed (which is not the case while
     * emulating real size)
     *
     * @return true if zooming is allowed
     */
    boolean isZoomingAllowed() {
        return mZoomInButton.isEnabled();
    }

    boolean isZoomingRealSize() {
        return mZoomRealSizeButton.getSelection();
    }

    /**
     * Rescales canvas.
     * @param direction +1 for zoom in, -1 for zoom out
     */
    void rescale(int direction) {
        LayoutCanvas canvas = mEditor.getCanvasControl();
        double s = canvas.getScale();

        if (direction > 0) {
            s = s * 1.2;
        } else {
            s = s / 1.2;
        }

        // Some operations are faster if the zoom is EXACTLY 1.0 rather than ALMOST 1.0.
        // (This is because there is a fast-path when image copying and the scale is 1.0;
        // in that case it does not have to do any scaling).
        //
        // If you zoom out 10 times and then back in 10 times, small rounding errors mean
        // that you end up with a scale=1.0000000000000004. In the cases, when you get close
        // to 1.0, just make the zoom an exact 1.0.
        if (Math.abs(s-1.0) < 0.0001) {
            s = 1.0;
        }

        canvas.setScale(s, true /*redraw*/);
    }

    /**
     * Reset the canvas scale to 100%
     */
    void resetScale() {
        mEditor.getCanvasControl().setScale(1, true /*redraw*/);
    }

    /**
     * Reset the canvas scale to best fit (so content is as large as possible without scrollbars)
     */
    void rescaleToFit(boolean onlyZoomOut) {
        mEditor.getCanvasControl().setFitScale(onlyZoomOut, true /*allowZoomIn*/);
    }

    boolean rescaleToReal(boolean real) {
        if (real) {
            return computeAndSetRealScale(true /*redraw*/);
        } else {
            // reset the scale to 100%
            mEditor.getCanvasControl().setScale(1, true /*redraw*/);
            return true;
        }
    }

    boolean computeAndSetRealScale(boolean redraw) {
        // compute average dpi of X and Y
        ConfigurationChooser chooser = mEditor.getConfigurationChooser();
        Configuration config = chooser.getConfiguration();
        Device device = config.getDevice();
        Screen screen = device.getDefaultHardware().getScreen();
        double dpi = (screen.getXdpi() + screen.getYdpi()) / 2.;

        // get the monitor dpi
        float monitor = AdtPrefs.getPrefs().getMonitorDensity();
        if (monitor == 0.f) {
            ResolutionChooserDialog dialog = new ResolutionChooserDialog(chooser.getShell());
            if (dialog.open() == Window.OK) {
                monitor = dialog.getDensity();
                AdtPrefs.getPrefs().setMonitorDensity(monitor);
            } else {
                return false;
            }
        }

        mEditor.getCanvasControl().setScale(monitor / dpi, redraw);
        return true;
    }
}