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/******************************************************************************* * Copyright (c) 2000, 2018 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.swt.graphics; import org.eclipse.swt.internal.*; import org.eclipse.swt.internal.win32.*; /** * Instances of this class provide measurement information * about fonts including ascent, descent, height, leading * space between rows, and average character width. * <code>FontMetrics</code> are obtained from <code>GC</code>s * using the <code>getFontMetrics()</code> method. * * @see GC#getFontMetrics * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a> */ public final class FontMetrics { /** * On Windows, handle is a Win32 TEXTMETRIC struct * (Warning: This field is platform dependent) * <p> * <b>IMPORTANT:</b> This field is <em>not</em> part of the SWT * public API. It is marked public only so that it can be shared * within the packages provided by SWT. It is not available on all * platforms and should never be accessed from application code. * </p> * * @noreference This field is not intended to be referenced by clients. */ public TEXTMETRIC handle; /** * Prevents instances from being created outside the package. */ FontMetrics() { } /** * Compares the argument to the receiver, and returns true * if they represent the <em>same</em> object using a class * specific comparison. * * @param object the object to compare with this object * @return <code>true</code> if the object is the same as this object and <code>false</code> otherwise * * @see #hashCode */ @Override public boolean equals(Object object) { if (object == this) return true; if (!(object instanceof FontMetrics)) return false; TEXTMETRIC metric = ((FontMetrics) object).handle; return handle.tmHeight == metric.tmHeight && handle.tmAscent == metric.tmAscent && handle.tmDescent == metric.tmDescent && handle.tmInternalLeading == metric.tmInternalLeading && handle.tmExternalLeading == metric.tmExternalLeading && handle.tmAveCharWidth == metric.tmAveCharWidth && handle.tmMaxCharWidth == metric.tmMaxCharWidth && handle.tmWeight == metric.tmWeight && handle.tmOverhang == metric.tmOverhang && handle.tmDigitizedAspectX == metric.tmDigitizedAspectX && handle.tmDigitizedAspectY == metric.tmDigitizedAspectY && // handle.tmFirstChar == metric.tmFirstChar && // handle.tmLastChar == metric.tmLastChar && // handle.tmDefaultChar == metric.tmDefaultChar && // handle.tmBreakChar == metric.tmBreakChar && handle.tmItalic == metric.tmItalic && handle.tmUnderlined == metric.tmUnderlined && handle.tmStruckOut == metric.tmStruckOut && handle.tmPitchAndFamily == metric.tmPitchAndFamily && handle.tmCharSet == metric.tmCharSet; } /** * Returns the ascent of the font described by the receiver. A * font's <em>ascent</em> is the distance from the baseline to the * top of actual characters, not including any of the leading area, * measured in points. * * @return the ascent of the font */ public int getAscent() { return DPIUtil.autoScaleDown(handle.tmAscent - handle.tmInternalLeading); } /** * Returns the average character width, measured in points, * of the font described by the receiver. * * @return the average character width of the font * @since 3.107 */ public double getAverageCharacterWidth() { return getAverageCharWidth(); } /** * Returns the average character width, measured in points, * of the font described by the receiver. * * @return the average character width of the font * @deprecated Use getAverageCharacterWidth() instead */ public int getAverageCharWidth() { return DPIUtil.autoScaleDown(handle.tmAveCharWidth); } /** * Returns the descent of the font described by the receiver. A * font's <em>descent</em> is the distance from the baseline to the * bottom of actual characters, not including any of the leading area, * measured in points. * * @return the descent of the font */ public int getDescent() { return DPIUtil.autoScaleDown(handle.tmDescent); } /** * Returns the height of the font described by the receiver, * measured in points. A font's <em>height</em> is the sum of * its ascent, descent and leading area. * * @return the height of the font * * @see #getAscent * @see #getDescent * @see #getLeading */ public int getHeight() { return DPIUtil.autoScaleDown(handle.tmHeight); } /** * Returns the leading area of the font described by the * receiver. A font's <em>leading area</em> is the space * above its ascent which may include accents or other marks. * * @return the leading space of the font */ public int getLeading() { /* * HiHPI rounding problem (bug 490743 comment 17): * * API clients expect this invariant: * getHeight() == getLeading() + getAscent() + getDescent() * * Separate rounding of each RHS term can break the invariant. * * An additional problem is that ascent and descent are more important to * be as close as possible to the real value. Any necessary rounding * adjustment should go into leading, that's why compute this as a derived * value here: */ return getHeight() - getAscent() - getDescent(); } /** * Returns an integer hash code for the receiver. Any two * objects that return <code>true</code> when passed to * <code>equals</code> must return the same value for this * method. * * @return the receiver's hash * * @see #equals */ @Override public int hashCode() { return handle.tmHeight ^ handle.tmAscent ^ handle.tmDescent ^ handle.tmInternalLeading ^ handle.tmExternalLeading ^ handle.tmAveCharWidth ^ handle.tmMaxCharWidth ^ handle.tmWeight ^ handle.tmOverhang ^ handle.tmDigitizedAspectX ^ handle.tmDigitizedAspectY ^ // handle.tmFirstChar ^ handle.tmLastChar ^ handle.tmDefaultChar ^ handle.tmBreakChar ^ handle.tmItalic ^ handle.tmUnderlined ^ handle.tmStruckOut ^ handle.tmPitchAndFamily ^ handle.tmCharSet; } /** * Invokes platform specific functionality to allocate a new font metrics. * <p> * <b>IMPORTANT:</b> This method is <em>not</em> part of the public * API for <code>FontMetrics</code>. It is marked public only so that * it can be shared within the packages provided by SWT. It is not * available on all platforms, and should never be called from * application code. * </p> * * @param handle the <code>TEXTMETRIC</code> containing information about a font * @return a new font metrics object containing the specified <code>TEXTMETRIC</code> * * @noreference This method is not intended to be referenced by clients. */ public static FontMetrics win32_new(TEXTMETRIC handle) { FontMetrics fontMetrics = new FontMetrics(); fontMetrics.handle = handle; return fontMetrics; } }