| /* |
| * Copyright (C) 2017 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.support.graphics.drawable; |
| |
| import static android.support.annotation.RestrictTo.Scope.LIBRARY_GROUP; |
| |
| import static java.lang.Math.abs; |
| import static java.lang.Math.min; |
| |
| import android.content.Context; |
| import android.content.res.Resources; |
| import android.content.res.TypedArray; |
| import android.graphics.Path; |
| import android.graphics.PathMeasure; |
| import android.support.annotation.RestrictTo; |
| import android.support.v4.content.res.TypedArrayUtils; |
| import android.support.v4.graphics.PathParser; |
| import android.util.AttributeSet; |
| import android.view.InflateException; |
| import android.view.animation.Interpolator; |
| |
| import org.xmlpull.v1.XmlPullParser; |
| |
| /** |
| * An interpolator that can traverse a Path that extends from <code>Point</code> |
| * <code>(0, 0)</code> to <code>(1, 1)</code>. The x coordinate along the <code>Path</code> |
| * is the input value and the output is the y coordinate of the line at that point. |
| * This means that the Path must conform to a function <code>y = f(x)</code>. |
| * |
| * <p>The <code>Path</code> must not have gaps in the x direction and must not |
| * loop back on itself such that there can be two points sharing the same x coordinate. |
| * It is alright to have a disjoint line in the vertical direction:</p> |
| * <p><blockquote><pre> |
| * Path path = new Path(); |
| * path.lineTo(0.25f, 0.25f); |
| * path.moveTo(0.25f, 0.5f); |
| * path.lineTo(1f, 1f); |
| * </pre></blockquote></p> |
| * @hide |
| */ |
| @RestrictTo(LIBRARY_GROUP) |
| public class PathInterpolatorCompat implements Interpolator { |
| |
| // This governs how accurate the approximation of the Path is. |
| private static final float PRECISION = 0.002f; |
| public static final int MAX_NUM_POINTS = 3000; |
| public static final double EPSILON = 0.00001; |
| |
| private float[] mX; // x coordinates in the line |
| |
| private float[] mY; // y coordinates in the line |
| |
| public PathInterpolatorCompat(Context context, AttributeSet attrs, XmlPullParser parser) { |
| this(context.getResources(), context.getTheme(), attrs, parser); |
| } |
| |
| public PathInterpolatorCompat(Resources res, Resources.Theme theme, AttributeSet attrs, |
| XmlPullParser parser) { |
| TypedArray a = TypedArrayUtils.obtainAttributes(res, theme, |
| attrs, AndroidResources.STYLEABLE_PATH_INTERPOLATOR); |
| parseInterpolatorFromTypeArray(a, parser); |
| a.recycle(); |
| } |
| |
| private void parseInterpolatorFromTypeArray(TypedArray a, XmlPullParser parser) { |
| // If there is pathData defined in the xml file, then the controls points |
| // will be all coming from pathData. |
| if (TypedArrayUtils.hasAttribute(parser, "pathData")) { |
| String pathData = TypedArrayUtils.getNamedString(a, parser, "pathData", |
| AndroidResources.STYLEABLE_PATH_INTERPOLATOR_PATH_DATA); |
| Path path = PathParser.createPathFromPathData(pathData); |
| if (path == null) { |
| throw new InflateException("The path is null, which is created" |
| + " from " + pathData); |
| } |
| initPath(path); |
| } else { |
| if (!TypedArrayUtils.hasAttribute(parser, "controlX1")) { |
| throw new InflateException("pathInterpolator requires the controlX1 attribute"); |
| } else if (!TypedArrayUtils.hasAttribute(parser, "controlY1")) { |
| throw new InflateException("pathInterpolator requires the controlY1 attribute"); |
| } |
| float x1 = TypedArrayUtils.getNamedFloat(a, parser, "controlX1", |
| AndroidResources.STYLEABLE_PATH_INTERPOLATOR_CONTROL_X_1, 0); |
| float y1 = TypedArrayUtils.getNamedFloat(a, parser, "controlY1", |
| AndroidResources.STYLEABLE_PATH_INTERPOLATOR_CONTROL_Y_1, 0); |
| |
| boolean hasX2 = TypedArrayUtils.hasAttribute(parser, "controlX2"); |
| boolean hasY2 = TypedArrayUtils.hasAttribute(parser, "controlY2"); |
| |
| if (hasX2 != hasY2) { |
| throw new InflateException("pathInterpolator requires both controlX2 and" |
| + " controlY2 for cubic Beziers."); |
| } |
| |
| if (!hasX2) { |
| initQuad(x1, y1); |
| } else { |
| float x2 = TypedArrayUtils.getNamedFloat(a, parser, "controlX2", |
| AndroidResources.STYLEABLE_PATH_INTERPOLATOR_CONTROL_X_2, 0); |
| float y2 = TypedArrayUtils.getNamedFloat(a, parser, "controlY2", |
| AndroidResources.STYLEABLE_PATH_INTERPOLATOR_CONTROL_Y_2, 0); |
| initCubic(x1, y1, x2, y2); |
| } |
| } |
| } |
| |
| private void initQuad(float controlX, float controlY) { |
| Path path = new Path(); |
| path.moveTo(0, 0); |
| path.quadTo(controlX, controlY, 1f, 1f); |
| initPath(path); |
| } |
| |
| private void initCubic(float x1, float y1, float x2, float y2) { |
| Path path = new Path(); |
| path.moveTo(0, 0); |
| path.cubicTo(x1, y1, x2, y2, 1f, 1f); |
| initPath(path); |
| } |
| |
| private void initPath(Path path) { |
| final PathMeasure pathMeasure = new PathMeasure(path, false /* forceClosed */); |
| |
| final float pathLength = pathMeasure.getLength(); |
| final int numPoints = min(MAX_NUM_POINTS, (int) (pathLength / PRECISION) + 1); |
| |
| if (numPoints <= 0) { |
| throw new IllegalArgumentException("The Path has a invalid length " + pathLength); |
| } |
| |
| mX = new float[numPoints]; |
| mY = new float[numPoints]; |
| |
| final float[] position = new float[2]; |
| for (int i = 0; i < numPoints; ++i) { |
| final float distance = (i * pathLength) / (numPoints - 1); |
| pathMeasure.getPosTan(distance, position, null /* tangent */); |
| |
| mX[i] = position[0]; |
| mY[i] = position[1]; |
| } |
| |
| if (abs(mX[0]) > EPSILON || abs(mY[0]) > EPSILON || abs(mX[numPoints - 1] - 1) > EPSILON |
| || abs(mY[numPoints - 1] - 1) > EPSILON) { |
| throw new IllegalArgumentException("The Path must start at (0,0) and end at (1,1)" |
| + " start: " + mX[0] + "," + mY[0] + " end:" + mX[numPoints - 1] + "," |
| + mY[numPoints - 1]); |
| |
| } |
| |
| float prevX = 0; |
| int componentIndex = 0; |
| for (int i = 0; i < numPoints; i++) { |
| float x = mX[componentIndex++]; |
| if (x < prevX) { |
| throw new IllegalArgumentException("The Path cannot loop back on itself, x :" + x); |
| } |
| mX[i] = x; |
| prevX = x; |
| } |
| |
| if (pathMeasure.nextContour()) { |
| throw new IllegalArgumentException("The Path should be continuous," |
| + " can't have 2+ contours"); |
| } |
| } |
| |
| /** |
| * Using the line in the Path in this interpolator that can be described as |
| * <code>y = f(x)</code>, finds the y coordinate of the line given <code>t</code> |
| * as the x coordinate. Values less than 0 will always return 0 and values greater |
| * than 1 will always return 1. |
| * |
| * @param t Treated as the x coordinate along the line. |
| * @return The y coordinate of the Path along the line where x = <code>t</code>. |
| * @see Interpolator#getInterpolation(float) |
| */ |
| @Override |
| public float getInterpolation(float t) { |
| if (t <= 0) { |
| return 0; |
| } else if (t >= 1) { |
| return 1; |
| } |
| // Do a binary search for the correct x to interpolate between. |
| int startIndex = 0; |
| int endIndex = mX.length - 1; |
| |
| while (endIndex - startIndex > 1) { |
| int midIndex = (startIndex + endIndex) / 2; |
| if (t < mX[midIndex]) { |
| endIndex = midIndex; |
| } else { |
| startIndex = midIndex; |
| } |
| } |
| |
| float xRange = mX[endIndex] - mX[startIndex]; |
| if (xRange == 0) { |
| return mY[startIndex]; |
| } |
| |
| float tInRange = t - mX[startIndex]; |
| float fraction = tInRange / xRange; |
| |
| float startY = mY[startIndex]; |
| float endY = mY[endIndex]; |
| return startY + (fraction * (endY - startY)); |
| } |
| } |