package com.github.lgooddatepicker.zinternaltools;
import java.awt.Font;
import java.awt.FontMetrics;
import java.time.LocalDate;
import java.time.Month;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
import javax.swing.JTextField;
/**
* CalculateMinimumDateFieldSize, This class is used to calculate the minimum horizontal size needed
* for text fields that hold dates. (Such as the text field in the DatePicker component.)
*
* The size that is returned is designed to be the smallest size that will hold the longest
* displayable date under current DatePickerSettings, without cropping the text. The "longest date",
* needs to take into account the following factors: The longest (in pixels) month name in the
* current locale, the font object for valid dates (including the font type and size), and the
* currently set display format for AD dates.
*/
public class CalculateMinimumDateFieldSize {
/**
* getFormattedDateWidthInPixels, This returns the width (in pixels) of the longest formatted
* date, using the supplied DateTimeFormatter instance, locale, and font.
*
* The month that will be used for the length calculation will be the "longest text month"
* according to the function getLongestTextMonthInLocale().
*
* You may optionally add extra characters to the longestDateString that is used in the
* calculation, by supplying a nonzero value for the parameter numberOfExtraCharacters.
*
* formatCE: This is the date format that should be used in the calculation. Longer (wider)
* formats will result in wider printed dates.
*
* locale: This is the locale that you wish to use in the calculation. The width of the date
* string (and the width of the month names) will be different depending on the locale that is
* used to translate and format the date.
*
* fontValidDate: This will be used to generate the font metrics for the calculation. Larger
* font types, and larger font sizes, will result in wider printed dates.
*
* numberOfExtraCharacters: This is the number of "extra" characters that you want to have used
* in calculating the width of the longest formatted date. If you don't wish for any extra
* characters to be used in the calculation, please supply zero for this value. If you wish to
* -shorten- the default date string, you may also supply a negative number of characters for
* this value.
*
* Implementation details: Note that any formatted date could be made longer by using years
* greater than four digits, or by using BC years. This function assumes four digit Common Era
* years, in performing its calculations.
*/
static public int getFormattedDateWidthInPixels(DateTimeFormatter formatCE, Locale locale,
Font fontValidDate, int numberOfExtraCharacters) {
// Create the font metrics that will be used in the calculation.
JTextField textField = new JTextField();
FontMetrics fontMetrics = textField.getFontMetrics(fontValidDate);
// Calculate the "longest text month".
Month longestTextMonth = getLongestTextMonthInLocale(locale, fontMetrics);
// Create the longest dates with a text month format, and a numeric month format.
// Both dates will have a four digit year, and a two digit day of the month.
LocalDate longestTextDate = LocalDate.of(2000, longestTextMonth, 28);
LocalDate longestNumericDate = LocalDate.of(2000, Month.DECEMBER, 28);
// Generate the long date strings. Note, The locale is built into the formatter instance.
String longestTextDateString = longestTextDate.format(formatCE);
String longestNumericDateString = longestNumericDate.format(formatCE);
// Get the width of the longest date string (in pixels), using the supplied font metrics.
int textDateWidth = fontMetrics.stringWidth(longestTextDateString);
int numericDateWidth = fontMetrics.stringWidth(longestNumericDateString);
int longestDateWidth = Math.max(textDateWidth, numericDateWidth);
// Add space for two characters, because one character appears to be needed, and one more
// allows room for BC dates.
int singleNumericCharacterWidth = fontMetrics.stringWidth("8");
longestDateWidth += (2 * singleNumericCharacterWidth);
// If requested, pad the result with space for any (programmer specified) extra characters.
longestDateWidth += (numberOfExtraCharacters * singleNumericCharacterWidth);
// Return the width of the longest formatted date, in pixels.
return longestDateWidth;
}
/**
* getLongestTextMonthInLocale,
*
* For the supplied locale, this returns the month that has the longest translated, "formatting
* version", "long text version" month name. The version of the month name string that is used
* for comparison is further defined below.
*
* Note that this does not return the longest month for numeric month date formats. The longest
* month in entirely numeric formats is always December. (Month number 12).
*
* The compared month names are the "formatting version" of the translated month names (not the
* standalone version). In some locales such as Russian and Czech, the formatting version can be
* different from the standalone version. The "formatting version" is the name of the month that
* would be used in a formatted date. The standalone version is only used when the month is
* displayed by itself.
*
* The month names that are used for comparison are also the "long version" of the month names,
* not the short (abbreviated) version.
*
* The translated month names are compared using the supplied font metrics.
*
* This returns the longest month, as defined by the above criteria. If two or more months are
* "tied" as the "longest month", then the longest month that is closest to the end of the year
* will be the one that is returned.
*/
static private Month getLongestTextMonthInLocale(Locale locale, FontMetrics fontMetrics) {
// Get the "formatting names" of all the months for this locale.
// Request the capitalized long version of the translated month names.
String[] formattingMonthNames = ExtraDateStrings.getFormattingMonthNamesArray(
locale, true, false);
// Find out which month is longest, using the supplied font metrics.
int longestMonthWidth = 0;
Month longestMonth = Month.JANUARY;
for (int i = 0; i < formattingMonthNames.length; ++i) {
int currentMonthWidth = fontMetrics.stringWidth(formattingMonthNames[i]);
if (currentMonthWidth >= longestMonthWidth) {
int oneBasedMonthIndex = (i + 1);
longestMonth = Month.of(oneBasedMonthIndex);
longestMonthWidth = currentMonthWidth;
}
}
return longestMonth;
}
}
