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 17 package com.androidplot.util; 18 19 import android.graphics.PointF; 20 import android.graphics.RectF; 21 22 /** 23 * Utility methods for converting pixel coordinates into real values and vice versa. 24 */ 25 public class ValPixConverter { 26 private static final int ZERO = 0; 27 28 valToPix(double val, double min, double max, float lengthPix, boolean flip)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 range(double min, double max)44 public static double range(double min, double max) { 45 return (max-min); 46 } 47 48 valPerPix(double min, double max, float lengthPix)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 */ pixToVal(float pix, double min, double max, float lengthPix, boolean flip)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 */ valToPix(Number x, Number y, RectF plotArea, Number minX, Number maxX, Number minY, Number maxY)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