1/*
2 * Copyright 2012 AndroidPlot.com
3 *
4 *    Licensed under the Apache License, Version 2.0 (the "License");
5 *    you may not use this file except in compliance with the License.
6 *    You may obtain a copy of the License at
7 *
8 *        http://www.apache.org/licenses/LICENSE-2.0
9 *
10 *    Unless required by applicable law or agreed to in writing, software
11 *    distributed under the License is distributed on an "AS IS" BASIS,
12 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 *    See the License for the specific language governing permissions and
14 *    limitations under the License.
15 */
16
17package com.androidplot.util;
18
19import android.graphics.PointF;
20import android.graphics.RectF;
21
22/**
23 * Utility methods for converting pixel coordinates into real values and vice versa.
24 */
25public class ValPixConverter {
26    private static final int ZERO = 0;
27
28
29    public static float valToPix(double val, double min, double max, float lengthPix, boolean flip) {
30        if(lengthPix <= ZERO) {
31            throw new IllegalArgumentException("Length in pixels must be greater than 0.");
32        }
33        double range = range(min, max);
34        double scale = lengthPix / range;
35        double raw = val - min;
36        float pix = (float)(raw * scale);
37
38        if(flip) {
39            pix = (lengthPix - pix);
40        }
41        return pix;
42    }
43
44    public static double range(double min, double max) {
45        return (max-min);
46    }
47
48
49    public static double valPerPix(double min, double max, float lengthPix) {
50        double valRange = range(min, max);
51        return valRange/lengthPix;
52    }
53
54    /**
55     * Convert a value in pixels to the type passed into min/max
56     * @param pix
57     * @param min
58     * @param max
59     * @param lengthPix
60     * @param flip True if the axis should be reversed before calculated. This is the case
61     * with the y axis for screen coords.
62     * @return
63     */
64    public static double pixToVal(float pix, double min, double max, float lengthPix, boolean flip) {
65        if(pix < ZERO) {
66            throw new IllegalArgumentException("pixel values cannot be negative.");
67        }
68
69        if(lengthPix <= ZERO) {
70            throw new IllegalArgumentException("Length in pixels must be greater than 0.");
71        }
72        float pMult = pix;
73        if(flip) {
74            pMult = lengthPix - pix;
75        }
76        double range = range(min, max);
77        return ((range / lengthPix) * pMult) + min;
78    }
79
80    /**
81     * Converts a real value into a pixel value.
82     * @param x Real d (domain) component of the point to convert.
83     * @param y Real y (range) component of the point to convert.
84     * @param plotArea
85     * @param minX Minimum visible real value on the d (domain) axis.
86     * @param maxX Maximum visible real value on the y (domain) axis.
87     * @param minY Minimum visible real value on the y (range) axis.
88     * @param maxY Maximum visible real value on the y (range axis.
89     * @return
90     */
91    public static PointF valToPix(Number x, Number y, RectF plotArea, Number minX, Number maxX, Number minY, Number maxY) {
92        float pixX = ValPixConverter.valToPix(x.doubleValue(), minX.doubleValue(), maxX.doubleValue(), plotArea.width(), false) + (plotArea.left);
93        float pixY = ValPixConverter.valToPix(y.doubleValue(), minY.doubleValue(), maxY.doubleValue(), plotArea.height(), true) + plotArea.top;
94        return new PointF(pixX, pixY);
95    }
96}
97