Samples a stroke temporally into a given number of evenly-distributed points. - Android Graphics

Android examples for Graphics:Path Point

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Description

Samples a stroke temporally into a given number of evenly-distributed points.

Demo Code

/*//from   w w w . j a va  2 s. c om
 * Copyright (C) 2008-2009 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.
 */
import android.graphics.RectF;
import android.util.Log;
import java.util.ArrayList;
import java.util.Arrays;
import java.io.Closeable;
import java.io.IOException;
import static android.gesture.GestureConstants.*;

public class Main{
    /**
     * Samples a stroke temporally into a given number of evenly-distributed 
     * points.
     * 
     * @param stroke the gesture stroke to be sampled
     * @param numPoints the number of points
     * @return the sampled points in the form of [x1, y1, x2, y2, ..., xn, yn]
     */
    public static float[] temporalSampling(GestureStroke stroke,
            int numPoints) {
        final float increment = stroke.length / (numPoints - 1);
        int vectorLength = numPoints * 2;
        float[] vector = new float[vectorLength];
        float distanceSoFar = 0;
        float[] pts = stroke.points;
        float lstPointX = pts[0];
        float lstPointY = pts[1];
        int index = 0;
        float currentPointX = Float.MIN_VALUE;
        float currentPointY = Float.MIN_VALUE;
        vector[index] = lstPointX;
        index++;
        vector[index] = lstPointY;
        index++;
        int i = 0;
        int count = pts.length / 2;
        while (i < count) {
            if (currentPointX == Float.MIN_VALUE) {
                i++;
                if (i >= count) {
                    break;
                }
                currentPointX = pts[i * 2];
                currentPointY = pts[i * 2 + 1];
            }
            float deltaX = currentPointX - lstPointX;
            float deltaY = currentPointY - lstPointY;
            float distance = (float) Math.hypot(deltaX, deltaY);
            if (distanceSoFar + distance >= increment) {
                float ratio = (increment - distanceSoFar) / distance;
                float nx = lstPointX + ratio * deltaX;
                float ny = lstPointY + ratio * deltaY;
                vector[index] = nx;
                index++;
                vector[index] = ny;
                index++;
                lstPointX = nx;
                lstPointY = ny;
                distanceSoFar = 0;
            } else {
                lstPointX = currentPointX;
                lstPointY = currentPointY;
                currentPointX = Float.MIN_VALUE;
                currentPointY = Float.MIN_VALUE;
                distanceSoFar += distance;
            }
        }

        for (i = index; i < vectorLength; i += 2) {
            vector[i] = lstPointX;
            vector[i + 1] = lstPointY;
        }
        return vector;
    }
}

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