content: /*
   * Copyright (C) 2014 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 android.transition;
  
  import android.content.Context;
  import android.content.res.TypedArray;
  import android.graphics.Matrix;
  import android.graphics.Path;
  import android.graphics.PathMeasure;
  import android.util.AttributeSet;
  import android.util.PathParser;
  
  import com.android.internal.R;
  
  /**
   * A PathMotion that takes a Path pattern and applies it to the separation between two points.
   * The starting point of the Path will be moved to the origin and the end point will be scaled
   * and rotated so that it matches with the target end point.
   * <p>This may be used in XML as an element inside a transition.</p>
   * <pre>{@code
   * <changeBounds>
   *     <patternPathMotion android:patternPathData="M0 0 L0 100 L100 100"/>
   * </changeBounds>}
   * </pre>
   */
  public class PatternPathMotion extends PathMotion {
  
      private Path mOriginalPatternPath;
  
      private final Path mPatternPath = new Path();
  
      private final Matrix mTempMatrix = new Matrix();
  
      /**
       * Constructs a PatternPathMotion with a straight-line pattern.
       */
      public PatternPathMotion() {
          mPatternPath.lineTo(1, 0);
          mOriginalPatternPath = mPatternPath;
      }
  
      public PatternPathMotion(Context context, AttributeSet attrs) {
          TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.PatternPathMotion);
          try {
              String pathData = a.getString(R.styleable.PatternPathMotion_patternPathData);
              if (pathData == null) {
                  throw new RuntimeException("pathData must be supplied for patternPathMotion");
              }
              Path pattern = PathParser.createPathFromPathData(pathData);
              setPatternPath(pattern);
          } finally {
              a.recycle();
          }
  
      }
  
      /**
       * Creates a PatternPathMotion with the Path defining a pattern of motion between two
       * coordinates. The pattern will be translated, rotated, and scaled to fit between the start
       * and end points. The pattern must not be empty and must have the end point differ from the
       * start point.
       *
       * @param patternPath A Path to be used as a pattern for two-dimensional motion.
       */
      public PatternPathMotion(Path patternPath) {
          setPatternPath(patternPath);
      }
  
      /**
       * Returns the Path defining a pattern of motion between two coordinates.
       * The pattern will be translated, rotated, and scaled to fit between the start and end points.
       * The pattern must not be empty and must have the end point differ from the start point.
       *
       * @return the Path defining a pattern of motion between two coordinates.
       * @attr ref android.R.styleable#PatternPathMotion_patternPathData
       */
      public Path getPatternPath() {
          return mOriginalPatternPath;
      }
  
      /**
       * Sets the Path defining a pattern of motion between two coordinates.
       * The pattern will be translated, rotated, and scaled to fit between the start and end points.
       * The pattern must not be empty and must have the end point differ from the start point.
       *
       * @param patternPath A Path to be used as a pattern for two-dimensional motion.
       * @attr ref android.R.styleable#PatternPathMotion_patternPathData
       */
      public void setPatternPath(Path patternPath) {
          PathMeasure pathMeasure = new PathMeasure(patternPath, false);
          float length = pathMeasure.getLength();
          float[] pos = new float[2];
          pathMeasure.getPosTan(length, pos, null);
          float endX = pos[0];
          float endY = pos[1];
          pathMeasure.getPosTan(0, pos, null);
          float startX = pos[0];
          float startY = pos[1];
  
          if (startX == endX && startY == endY) {
              throw new IllegalArgumentException("pattern must not end at the starting point");
          }
  
          mTempMatrix.setTranslate(-startX, -startY);
          float dx = endX - startX;
          float dy = endY - startY;
          float distance = (float) Math.hypot(dx, dy);
          float scale = 1 / distance;
          mTempMatrix.postScale(scale, scale);
          double angle = Math.atan2(dy, dx);
          mTempMatrix.postRotate((float) Math.toDegrees(-angle));
          patternPath.transform(mTempMatrix, mPatternPath);
          mOriginalPatternPath = patternPath;
      }
  
      @Override
      public Path getPath(float startX, float startY, float endX, float endY) {
          double dx = endX - startX;
          double dy = endY - startY;
          float length = (float) Math.hypot(dx, dy);
          double angle = Math.atan2(dy, dx);
  
          mTempMatrix.setScale(length, length);
          mTempMatrix.postRotate((float) Math.toDegrees(angle));
          mTempMatrix.postTranslate(startX, startY);
          Path path = new Path();
          mPatternPath.transform(mTempMatrix, path);
          return path;
      }
  
  }
  