designer/src/com/android/tools/idea/uibuilder/handlers/relative/RelativeLayoutHandler.java

/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * 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.android.tools.idea.uibuilder.handlers.relative;

import com.android.annotations.NonNull;
import com.android.annotations.Nullable;
import com.android.tools.idea.uibuilder.api.*;
import com.android.tools.idea.uibuilder.graphics.NlGraphics;
import com.android.tools.idea.uibuilder.model.AndroidCoordinate;
import com.android.tools.idea.uibuilder.model.NlComponent;
import com.android.tools.idea.uibuilder.model.SegmentType;
import com.android.tools.idea.uibuilder.model.TextDirection;
import com.android.tools.idea.uibuilder.surface.ScreenView;
import com.google.common.collect.Lists;

import java.awt.*;
import java.util.List;

/** Handler for the {@code <RelativeLayout>} layout */
public class RelativeLayoutHandler extends ViewGroupHandler {
  @Override
  public boolean paintConstraints(@NonNull ScreenView screenView, @NonNull Graphics2D graphics, @NonNull NlComponent component) {
    NlGraphics g = new NlGraphics(graphics, screenView);
    Iterable<NlComponent> iterable = component.getChildren();
    List<NlComponent> children = Lists.newArrayList(iterable);
    ConstraintPainter.paintSelectionFeedback(g, component, children, true, TextDirection.LEFT_TO_RIGHT);
    return false;
  }

  @Override
  @Nullable
  public DragHandler createDragHandler(@NonNull ViewEditor editor,
                                       @NonNull NlComponent layout,
                                       @NonNull List<NlComponent> components,
                                       @NonNull DragType type) {
    final RelativeDragHandler moveHandler = new RelativeDragHandler(editor, layout, components);
    return new DragHandler(editor, this, layout, components, type) {
      @Nullable
      @Override
      public String update(@AndroidCoordinate int x, @AndroidCoordinate int y, int modifiers) {
        super.update(x, y, modifiers);
        NlComponent primary = components.get(0);
        int deltaX = lastX - startX;
        int deltaY = lastY - startY;
        moveHandler.updateMove(primary, deltaX, deltaY, modifiers);

        return null;
      }

      @Override
      public void paint(@NonNull NlGraphics graphics) {
        GuidelinePainter.paint(graphics, moveHandler);
      }

      @Override
      public void commit(@AndroidCoordinate int x, @AndroidCoordinate int y, int modifiers) {
        moveHandler.removeCycles();

        NlComponent previous = null;
        for (NlComponent component : components) {
          if (previous == null) {
            moveHandler.applyConstraints(component);
          } else {
            // Arrange the nodes next to each other, depending on which
            // edge we are attaching to. For example, if attaching to the
            // top edge, arrange the subsequent nodes in a column below it.
            //
            // TODO: Try to do something smarter here where we detect
            // constraints between the dragged edges, and we preserve these.
            // We have to do this carefully though because if the
            // constraints go through some other nodes not part of the
            // selection, this doesn't work right, and you might be
            // dragging several connected components, which we'd then
            // need to stitch together such that they are all visible.

            moveHandler.attachPrevious(previous, component);
          }
          previous = component;
        }
      }
    };
  }

  @Override
  @Nullable
  public ResizeHandler createResizeHandler(@NonNull ViewEditor editor,
                                           @NonNull NlComponent component,
                                           @Nullable SegmentType horizontalEdgeType,
                                           @Nullable SegmentType verticalEdgeType) {
    NlComponent parent = component.getParent();
    if (parent == null) {
      return null;
    }
    final RelativeResizeHandler resizeHandler = new RelativeResizeHandler(editor, parent, component, horizontalEdgeType, verticalEdgeType);

    return new ResizeHandler(editor, this, component, horizontalEdgeType, verticalEdgeType) {
      @Nullable
      @Override
      public String update(@AndroidCoordinate int x,
                           @AndroidCoordinate int y,
                           int modifiers,
                           @NonNull @AndroidCoordinate Rectangle newBounds) {
        super.update(x, y, modifiers, newBounds);
        resizeHandler.updateResize(component, newBounds, modifiers);
        return null;
      }

      @Override
      public void commit(@AndroidCoordinate int px,
                         @AndroidCoordinate int py,
                         int modifiers,
                         @NonNull @AndroidCoordinate Rectangle newBounds) {
        resizeHandler.removeCycles();
        resizeHandler.applyConstraints(component);
      }

      @Override
      public void paint(@NonNull NlGraphics graphics) {
        GuidelinePainter.paint(graphics, resizeHandler);
      }
    };
  }
}