API Review: Improve javadoc.

Bug 17189781
Also rename PatternMotion to PatternPathMotion

Change-Id: I1c4dcbdd65e33cf9de1504277e31f9f7ede0380d

1 files changed, 149 insertions, 0 deletions

diff --git a/core/java/android/transition/PatternPathMotion.java b/core/java/android/transition/PatternPathMotion.java
new file mode 100644
index 000000000000..a609df6a0a39
--- /dev/null
+++ b/core/java/android/transition/PatternPathMotion.java
@@ -0,0 +1,149 @@
+/*
+ * 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 com.android.internal.R;
+
+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.FloatMath;
+import android.util.PathParser;
+
+/**
+ * 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
+ * &lt;changeBounds>
+ *     &lt;patternPathMotion android:patternPathData="M0 0 L0 100 L100 100"/>
+ * &lt;/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 = distance(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) {
+        float dx = endX - startX;
+        float dy = endY - startY;
+        float length = distance(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;
+    }
+
+    private static float distance(float x, float y) {
+        return FloatMath.sqrt((x * x) + (y * y));
+    }
+}