org.swtchart/src/org/swtchart/internal/axis/AxisTickLabels.java

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/*******************************************************************************
 * Copyright (c) 2008-2014 SWTChart project. All rights reserved.
 *
 * This code is distributed under the terms of the Eclipse Public License v1.0
 * which is available at http://www.eclipse.org/legal/epl-v10.html
 *******************************************************************************/
package org.swtchart.internal.axis;

import java.math.BigDecimal;
import java.text.DecimalFormat;
import java.text.Format;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.graphics.Transform;
import org.eclipse.swt.widgets.Display;
import org.swtchart.Chart;
import org.swtchart.IAxis.Position;
import org.swtchart.internal.ChartLayoutData;
import org.swtchart.internal.Util;

public class AxisTickLabels implements PaintListener {

    private final Chart chart;

    private final Axis axis;

    private Color foreground;

    private int widthHint;

    private int heightHint;

    private Rectangle bounds;

    private final ArrayList<Double> tickLabelValues;

    private final ArrayList<String> tickLabels;

    private final ArrayList<Integer> tickLabelPositions;

    private final ArrayList<Boolean> tickVisibilities;

    private Format format;

    private static final int DEFAULT_FOREGROUND = SWT.COLOR_BLUE;

    private static final Font DEFAULT_FONT = Display.getDefault()
            .getSystemFont();

    private static final String DEFAULT_DECIMAL_FORMAT = "#.###########";

    private Map<Integer, Integer[]> possibleTickSteps;

    private int timeUnit;

    private Font font;

    protected AxisTickLabels(Chart chart, Axis axis) {
        this.chart = chart;
        this.axis = axis;

        tickLabelValues = new ArrayList<Double>();
        tickLabels = new ArrayList<String>();
        tickLabelPositions = new ArrayList<Integer>();
        tickVisibilities = new ArrayList<Boolean>();

        initializePossibleTickSteps();

        font = DEFAULT_FONT;
        foreground = Display.getDefault().getSystemColor(DEFAULT_FOREGROUND);
        chart.addPaintListener(this);
    }

    private void initializePossibleTickSteps() {
        final Integer[] milliseconds = { 1, 2, 5, 10, 20, 50, 100, 200, 500,
                999 };
        final Integer[] seconds = { 1, 2, 5, 10, 15, 20, 30, 59 };
        final Integer[] minutes = { 1, 2, 3, 5, 10, 15, 20, 30, 59 };
        final Integer[] hours = { 1, 2, 3, 4, 6, 12, 22 };
        final Integer[] dates = { 1, 7, 14, 28 };
        final Integer[] months = { 1, 2, 3, 4, 6, 11 };
        final Integer[] years = { 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000 };

        possibleTickSteps = new HashMap<Integer, Integer[]>();
        possibleTickSteps.put(Calendar.MILLISECOND, milliseconds);
        possibleTickSteps.put(Calendar.SECOND, seconds);
        possibleTickSteps.put(Calendar.MINUTE, minutes);
        possibleTickSteps.put(Calendar.HOUR_OF_DAY, hours);
        possibleTickSteps.put(Calendar.DATE, dates);
        possibleTickSteps.put(Calendar.MONTH, months);
        possibleTickSteps.put(Calendar.YEAR, years);
    }

    public void setForeground(Color color) {
        if (color == null) {
            foreground = Display.getDefault()
                    .getSystemColor(DEFAULT_FOREGROUND);
        } else {
            foreground = color;
        }
    }

    protected Color getForeground() {
        if (foreground.isDisposed()) {
            foreground = Display.getDefault()
                    .getSystemColor(DEFAULT_FOREGROUND);
        }
        return foreground;
    }

    protected void update(int length) {
        tickLabelValues.clear();
        tickLabels.clear();
        tickLabelPositions.clear();

        if (axis.isValidCategoryAxis()) {
            updateTickLabelForCategoryAxis(length);
        } else if (axis.isLogScaleEnabled()) {
            updateTickLabelForLogScale(length);
        } else if (axis.isDateEnabled()) {
            updateTickLabelForDateAxis(length);
        } else {
            updateTickLabelForLinearScale(length);
        }

        updateTickVisibility();
    }

    private void updateTickLabelForDateAxis(int length) {
        double min = axis.getRange().lower;
        double max = axis.getRange().upper;

        double gridStepHint = Math.abs(max - min) / length
                * axis.getTick().getTickMarkStepHint();

        timeUnit = getTimeUnit(gridStepHint);

        if (timeUnit == Calendar.MILLISECOND || timeUnit == Calendar.SECOND
                || timeUnit == Calendar.MINUTE
                || timeUnit == Calendar.HOUR_OF_DAY
                || timeUnit == Calendar.DATE) {

            Integer[] steps = possibleTickSteps.get(timeUnit);
            for (int i = 0; i < steps.length - 1; i++) {
                if (gridStepHint < (getPeriodInMillis(timeUnit, steps[i]) + getPeriodInMillis(
                        timeUnit, steps[i + 1])) / 2d) {
                    BigDecimal gridStep = BigDecimal.valueOf(getPeriodInMillis(
                            timeUnit, steps[i]));
                    updateTickLabelForLinearScale(length, gridStep);
                    break;
                }
            }
        } else if (timeUnit == Calendar.MONTH || timeUnit == Calendar.YEAR) {

            updateTickLabelForMonthOrYear(length, gridStepHint, timeUnit);
        }
    }

    private void updateTickLabelForMonthOrYear(int length, double gridStepHint,
            int tickStepUnit) {
        double min = axis.getRange().lower;
        double max = axis.getRange().upper;

        // get initial position
        Calendar cal = Calendar.getInstance();
        cal.setTime(new Date((long) min));
        int month = cal.get(Calendar.MONTH);
        int year = cal.get(Calendar.YEAR);
        if (tickStepUnit == Calendar.MONTH) {
            if (month == Calendar.DECEMBER) {
                year++;
                month = Calendar.JANUARY;
            } else {
                month++;
            }
        } else if (tickStepUnit == Calendar.YEAR) {
            month = Calendar.JANUARY;
            year++;
        }

        // get tick step
        Integer[] steps = possibleTickSteps.get(tickStepUnit);
        int step = steps[steps.length - 1];
        for (int i = 0; i < steps.length - 1; i++) {
            if (gridStepHint < (getPeriodInMillis(tickStepUnit, steps[i]) + getPeriodInMillis(
                    tickStepUnit, steps[i + 1])) / 2d) {
                step = steps[i];
                break;
            }
        }

        // set tick labels
        cal.clear();
        cal.set(year, month, 1);
        while (cal.getTimeInMillis() < max) {
            tickLabelValues.add(Double.valueOf(cal.getTimeInMillis()));
            tickLabels.add(format(cal.getTimeInMillis()));
            int tickLabelPosition = (int) ((cal.getTimeInMillis() - min)
                    / (max - min) * length);
            tickLabelPositions.add(tickLabelPosition);
            if (tickStepUnit == Calendar.MONTH) {
                month += step;
                if (month + step > Calendar.DECEMBER) {
                    year++;
                    month -= Calendar.DECEMBER + 1;
                }
            } else if (tickStepUnit == Calendar.YEAR) {
                year += step;
            }
            cal.clear();
            cal.set(year, month, 1);
        }
    }

    private void updateTickLabelForCategoryAxis(int length) {
        String[] series = axis.getCategorySeries();
        if (series == null) {
            return;
        }

        int min = (int) axis.getRange().lower;
        int max = (int) axis.getRange().upper;

        int sizeOfTickLabels = (series.length < max - min + 1) ? series.length
                : max - min + 1;
        int initialIndex = (min < 0) ? 0 : min;

        for (int i = 0; i < sizeOfTickLabels; i++) {
            tickLabels.add(series[i + initialIndex]);

            int tickLabelPosition = (int) (length * (i + 0.5) / sizeOfTickLabels);
            tickLabelPositions.add(tickLabelPosition);
        }
    }

    private void updateTickLabelForLogScale(int length) {
        double min = axis.getRange().lower;
        double max = axis.getRange().upper;

        int digitMin = (int) Math.ceil(Math.log10(min));
        int digitMax = (int) Math.ceil(Math.log10(max));

        final BigDecimal MIN = BigDecimal.valueOf(min);
        BigDecimal tickStep = pow(10, digitMin - 1);
        BigDecimal firstPosition;

        if (MIN.remainder(tickStep).doubleValue() <= 0) {
            firstPosition = MIN.subtract(MIN.remainder(tickStep));
        } else {
            firstPosition = MIN.subtract(MIN.remainder(tickStep)).add(tickStep);
        }

        for (int i = digitMin; i <= digitMax; i++) {
            for (BigDecimal j = firstPosition; j.doubleValue() <= pow(10, i)
                    .doubleValue(); j = j.add(tickStep)) {
                if (j.doubleValue() > max) {
                    break;
                }

                if (axis.isDateEnabled()) {
                    Date date = new Date((long) j.doubleValue());
                    tickLabels.add(format(date));
                } else {
                    tickLabels.add(format(j.doubleValue()));
                }
                tickLabelValues.add(j.doubleValue());

                int tickLabelPosition = (int) ((Math.log10(j.doubleValue()) - Math
                        .log10(min)) / (Math.log10(max) - Math.log10(min)) * length);
                tickLabelPositions.add(tickLabelPosition);
            }
            tickStep = tickStep.multiply(pow(10, 1));
            firstPosition = tickStep.add(pow(10, i));
        }
    }

    private void updateTickLabelForLinearScale(int length) {
        double min = axis.getRange().lower;
        double max = axis.getRange().upper;
        updateTickLabelForLinearScale(length, getGridStep(length, min, max));
    }

    private void updateTickLabelForLinearScale(int length, BigDecimal tickStep) {
        double min = axis.getRange().lower;
        double max = axis.getRange().upper;

        final BigDecimal MIN = BigDecimal.valueOf(min);
        BigDecimal firstPosition;

        /* if (min % tickStep <= 0) */
        if (MIN.remainder(tickStep).doubleValue() <= 0) {
            /* firstPosition = min - min % tickStep */
            firstPosition = MIN.subtract(MIN.remainder(tickStep));
        } else {
            /* firstPosition = min - min % tickStep + tickStep */
            firstPosition = MIN.subtract(MIN.remainder(tickStep)).add(tickStep);
        }

        // the unit time starts from 1:00
        if (axis.isDateEnabled()) {
            BigDecimal zeroOclock = firstPosition.subtract(BigDecimal
                    .valueOf(3600000));
            if (MIN.compareTo(zeroOclock) == -1) {
                firstPosition = zeroOclock;
            }
        }

        for (BigDecimal b = firstPosition; b.doubleValue() <= max; b = b
                .add(tickStep)) {
            if (axis.isDateEnabled()) {
                Date date = new Date((long) b.doubleValue());
                tickLabels.add(format(date));
            } else {
                tickLabels.add(format(b.doubleValue()));
            }
            tickLabelValues.add(b.doubleValue());

            int tickLabelPosition = (int) ((b.doubleValue() - min)
                    / (max - min) * length);
            tickLabelPositions.add(tickLabelPosition);
        }
    }

    private void updateTickVisibility() {

        // initialize the array of tick label visibility state
        tickVisibilities.clear();
        for (int i = 0; i < tickLabelPositions.size(); i++) {
            tickVisibilities.add(Boolean.TRUE);
        }

        if (tickLabelPositions.size() == 0
                || axis.getTick().getTickLabelAngle() != 0) {
            return;
        }

        // set the tick label visibility
        int previousPosition = 0;
        for (int i = 0; i < tickLabelPositions.size(); i++) {

            // check if there is enough space to draw tick label
            boolean hasSpaceToDraw = true;
            if (i != 0) {
                hasSpaceToDraw = hasSpaceToDraw(previousPosition,
                        tickLabelPositions.get(i), tickLabels.get(i));
            }

            // check if the tick label value is major
            boolean isMajorTick = true;
            if (!axis.isValidCategoryAxis()) {
                if (axis.isLogScaleEnabled()) {
                    isMajorTick = isMajorTick(tickLabelValues.get(i));
                }

                // check if the same tick label is repeated
                String currentLabel = tickLabels.get(i);
                try {
                    double value = Double.parseDouble(currentLabel);
                    if (value != tickLabelValues.get(i)) {
                        isMajorTick = false;
                    }
                } catch (NumberFormatException e) {
                    // label is not decimal value but string
                }
            }

            if (hasSpaceToDraw && isMajorTick) {
                previousPosition = tickLabelPositions.get(i);
            } else {
                tickVisibilities.set(i, Boolean.FALSE);
            }
        }
    }

    private int getTimeUnit(double gridStepHint) {
        final Integer[] units = { Calendar.MILLISECOND, Calendar.SECOND,
                Calendar.MINUTE, Calendar.HOUR_OF_DAY, Calendar.DATE,
                Calendar.MONTH, Calendar.YEAR };

        for (Integer unit : units) {
            Integer[] steps = possibleTickSteps.get(unit);
            if (gridStepHint < (getPeriodInMillis(unit, steps[steps.length - 2]) + getPeriodInMillis(
                    unit, steps[steps.length - 1])) / 2d) {
                return unit;
            }
        }
        return Calendar.YEAR;
    }

    private static long getPeriodInMillis(int unit, int amount) {
        Calendar cal = Calendar.getInstance();
        cal.setTimeInMillis(0);
        cal.roll(unit, amount);
        return cal.getTimeInMillis();
    }

    private String format(Object obj) {
        if (format == null) {
            if (axis.isDateEnabled()) {
                String dateFormat = "yyyyy.MMMMM.dd";
                if (timeUnit == Calendar.MILLISECOND) {
                    dateFormat = "HH:mm:ss.SSS";
                } else if (timeUnit == Calendar.SECOND) {
                    dateFormat = "HH:mm:ss";
                } else if (timeUnit == Calendar.MINUTE) {
                    dateFormat = "HH:mm";
                } else if (timeUnit == Calendar.HOUR_OF_DAY) {
                    dateFormat = "dd HH:mm";
                } else if (timeUnit == Calendar.DATE) {
                    dateFormat = "MMMMM d";
                } else if (timeUnit == Calendar.MONTH) {
                    dateFormat = "yyyy MMMMM";
                } else if (timeUnit == Calendar.YEAR) {
                    dateFormat = "yyyy";
                }
                return new SimpleDateFormat(dateFormat).format(obj);
            }
            return new DecimalFormat(DEFAULT_DECIMAL_FORMAT).format(obj);
        }
        return format.format(obj);
    }

    private boolean isMajorTick(double tickValue) {
        if (!axis.isLogScaleEnabled()) {
            return true;
        }

        if (Math.log10(tickValue) % 1 == 0) {
            return true;
        }

        return false;
    }

    private boolean hasSpaceToDraw(int previousPosition, int tickLabelPosition,
            String tickLabel) {
        Point p = Util.getExtentInGC(axis.getTick().getFont(), tickLabel);
        int interval = tickLabelPosition - previousPosition;
        int textLength = axis.isHorizontalAxis() ? p.x : p.y;
        int padding = 3;

        return interval > textLength + padding;
    }

    public int getRightMarginHint(int length) {

        // search the most right tick label
        int mostRightLabelIndex = -1;
        for (int i = tickLabels.size() - 1; i >= 0; i--) {
            if (tickVisibilities.size() > i && tickVisibilities.get(i)) {
                mostRightLabelIndex = i;
                break;
            }
        }

        // calculate right margin hint
        int rightMarginHint = 0;
        if (mostRightLabelIndex != -1) {
            int position = tickLabelPositions.get(mostRightLabelIndex);
            double angle = axis.getTick().getTickLabelAngle();
            int textWidth = Util.getExtentInGC(axis.getTick().getFont(),
                    tickLabels.get(mostRightLabelIndex)).x;
            if (angle == 0) {
                rightMarginHint = Math.max(0, position - length
                        + (int) (textWidth / 2d));
            } else if (axis.getPosition() == Position.Secondary) {
                rightMarginHint = Math.max(0, position  - length
                        + (int) (textWidth * Math.cos(Math.toRadians(angle))));
            }
        }

        return rightMarginHint;
    }

    public int getLeftMarginHint(int length) {

        // search the most left tick label
        int mostLeftLabelIndex = -1;
        for (int i = 0; i < tickLabels.size(); i++) {
            if (tickVisibilities.size() > i && tickVisibilities.get(i)) {
                mostLeftLabelIndex = i;
                break;
            }
        }

        // calculate left margin hint
        int leftMarginHint = 0;
        if (mostLeftLabelIndex != -1) {
            int position = tickLabelPositions.get(mostLeftLabelIndex);
            double angle = axis.getTick().getTickLabelAngle();
            int textWidth = Util.getExtentInGC(axis.getTick().getFont(),
                    tickLabels.get(mostLeftLabelIndex)).x;
            if (angle == 0) {
                leftMarginHint = Math.max(0, (int) (textWidth / 2d) - position);
            } else if (axis.getPosition() == Position.Primary) {
                leftMarginHint = Math.max(0,
                        (int) (textWidth * Math.cos(Math.toRadians(angle)))
                                - position);
            }
        }

        return leftMarginHint;
    }

    public int getTickLabelMaxLength() {
        int maxLength = 0;
        for (int i = 0; i < tickLabels.size(); i++) {
            if (tickVisibilities.size() > i && tickVisibilities.get(i) == true) {
                Point p = Util.getExtentInGC(axis.getTick().getFont(),
                        tickLabels.get(i));
                if (p.x > maxLength) {
                    maxLength = p.x;
                }
            }
        }

        return maxLength;
    }

    private static BigDecimal pow(double base, int exponent) {
        BigDecimal value;
        if (exponent > 0) {
            value = BigDecimal.valueOf(base).pow(exponent);
        } else {
            value = BigDecimal.ONE.divide(BigDecimal.valueOf(base).pow(
                    -exponent));
        }
        return value;
    }

    private BigDecimal getGridStep(int lengthInPixels, double min, double max) {
        if (lengthInPixels <= 0) {
            throw new IllegalArgumentException(
                    "lengthInPixels must be positive value.");
        }
        if (min >= max) {
            throw new IllegalArgumentException("min must be less than max.");
        }

        double length = Math.abs(max - min);
        double gridStepHint = length / lengthInPixels
                * axis.getTick().getTickMarkStepHint();

        // gridStepHint --> mantissa * 10 ** exponent
        // e.g. 724.1 --> 7.241 * 10 ** 2
        double mantissa = gridStepHint;
        int exponent = 0;
        if (mantissa < 1) {
            while (mantissa < 1) {
                mantissa *= 10.0;
                exponent--;
            }
        } else {
            while (mantissa >= 10) {
                mantissa /= 10.0;
                exponent++;
            }
        }

        // calculate the grid step with hint.
        BigDecimal gridStep;
        if (mantissa > 7.5) {
            // gridStep = 10.0 * 10 ** exponent
            gridStep = BigDecimal.TEN.multiply(pow(10, exponent));
        } else if (mantissa > 3.5) {
            // gridStep = 5.0 * 10 ** exponent
            gridStep = BigDecimal.valueOf(5).multiply(pow(10, exponent));
        } else if (mantissa > 1.5) {
            // gridStep = 2.0 * 10 ** exponent
            gridStep = BigDecimal.valueOf(2).multiply(pow(10, exponent));
        } else {
            // gridStep = 1.0 * 10 ** exponent
            gridStep = pow(10, exponent);
        }
        return gridStep;
    }

    public ArrayList<Integer> getTickLabelPositions() {
        return tickLabelPositions;
    }

    protected ArrayList<Double> getTickLabelValues() {
        return tickLabelValues;
    }

    protected void setFont(Font font) {
        if (font == null) {
            this.font = DEFAULT_FONT;
        } else {
            this.font = font;
        }
    }

    public Font getFont() {
        if (font.isDisposed()) {
            font = DEFAULT_FONT;
        }
        return font;
    }

    public ChartLayoutData getLayoutData() {
        return new ChartLayoutData(widthHint, heightHint);
    }

    public void setBounds(int x, int y, int width, int height) {
        bounds = new Rectangle(x, y, width, height);
    }

    protected Rectangle getBounds() {
        return bounds;
    }

    protected void dispose() {
        if (!chart.isDisposed()) {
            chart.removePaintListener(this);
        }
    }

    protected void updateLayoutData() {
        widthHint = SWT.DEFAULT;
        heightHint = SWT.DEFAULT;
        if (!axis.getTick().isVisible()) {
            widthHint = 0;
            heightHint = 0;
        } else {
            if (axis.isHorizontalAxis()) {
                heightHint = Axis.MARGIN
                        + Util.getExtentInGC(getFont(), "dummy").y;
            } else {
                widthHint = Axis.MARGIN;
            }
        }
    }

    /*
     * @see PaintListener#paintControl(PaintEvent)
     */
    public void paintControl(PaintEvent e) {
        if (!axis.getTick().isVisible()) {
            return;
        }

        Color oldBackground = e.gc.getBackground();
        e.gc.setBackground(chart.getBackground());
        Color oldForeground = e.gc.getForeground();
        e.gc.setForeground(getForeground());
        if (axis.isHorizontalAxis()) {
            drawXTick(e.gc);
        } else {
            drawYTick(e.gc);
        }

        e.gc.setBackground(oldBackground);
        e.gc.setForeground(oldForeground);
    }

    private void drawXTick(GC gc) {
        int offset = axis.getTick().getAxisTickMarks().getBounds().x;

        // draw tick labels
        gc.setFont(axis.getTick().getFont());
        int angle = axis.getTick().getTickLabelAngle();
        for (int i = 0; i < tickLabelPositions.size(); i++) {
            if (axis.isValidCategoryAxis() || tickVisibilities.get(i) == true) {
                String text = tickLabels.get(i);
                int textWidth = gc.textExtent(text).x;
                int textHeight = gc.textExtent(text).y;
                if (angle == 0) {
                    int x = (int) (tickLabelPositions.get(i) - textWidth / 2d + offset);
                    gc.drawText(text, bounds.x + x, bounds.y);
                    continue;
                }

                float x, y;
                if (axis.getPosition() == Position.Primary) {
                    x = (float) (offset + bounds.x + tickLabelPositions.get(i)
                            - textWidth * Math.cos(Math.toRadians(angle)) - textHeight
                            / 2d * Math.sin(Math.toRadians(angle)));
                    y = (float) (bounds.y + textWidth
                            * Math.sin(Math.toRadians(angle)));
                } else {
                    x = (float) (offset + bounds.x + tickLabelPositions.get(i) - textHeight
                            / 2d * Math.sin(Math.toRadians(angle)));
                    y = (float) (bounds.y + bounds.height
                            * Math.sin(Math.toRadians(angle)));
                }
                drawRotatedText(gc, text, x, y, angle);
            }
        }
    }

    private static void drawRotatedText(GC gc, String text, float x, float y, int angle) {

        // set transform to rotate
        Transform transform = new Transform(gc.getDevice());
        transform.translate(x, y);
        transform.rotate(360 - angle);
        gc.setTransform(transform);
        gc.drawText(text, 0, 0);

        // clear transform
        transform.dispose();
        gc.setTransform(null);
    }

    private void drawYTick(GC gc) {
        int margin = Axis.MARGIN + AxisTickMarks.TICK_LENGTH;

        // draw tick labels
        gc.setFont(axis.getTick().getFont());
        int figureHeight = gc.textExtent("dummy").y;
        for (int i = 0; i < tickLabelPositions.size(); i++) {
            if (tickVisibilities.size() == 0 || tickLabels.size() == 0) {
                break;
            }

            if (tickVisibilities.get(i) == true) {
                String text = tickLabels.get(i);
                int x = Axis.MARGIN;
                if (tickLabels.get(0).startsWith("-") && !text.startsWith("-")) {
                    x += gc.textExtent("-").x;
                }
                int y = (int) (bounds.height - 1 - tickLabelPositions.get(i)
                        - figureHeight / 2.0 - margin);
                gc.drawText(text, bounds.x + x, bounds.y + y);
            }
        }
    }

    protected void setFormat(Format format) {
        this.format = format;
    }

    protected Format getFormat() {
        return format;
    }
}

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