Add native font enumeration API (667b69a0) · Commits · e / os / platform_frameworks_native

include/android/system_fonts.h

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		/*
		* Copyright (C) 2018 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		/**
		* @file system_fonts.h
		* @brief Provides the system font configurations.
		*
		* These APIs provides the list of system installed font files with additional metadata about the
		* font.
		*
		* The ASystemFontIterator_open method will give you an iterator which can iterate all system
		* installed font files as shown in the following example.
		*
		* <code>
		* ASystemFontIterator* iterator = ASystemFontIterator_open();
		* ASystemFont* font = NULL;
		*
		* while ((font = ASystemFontIterator_next(iterator)) != nullptr) {
		* // Look if the font is your desired one.
		* if (ASystemFont_getWeight(font) == 400 && !ASystemFont_isItalic(font)
		* && ASystemFont_getLocale(font) == NULL) {
		* break;
		* }
		* ASystemFont_close(font);
		* }
		* ASystemFontIterator_close(iterator);
		*
		* int fd = open(ASystemFont_getFontFilePath(font), O_RDONLY);
		* int collectionIndex = ASystemFont_getCollectionINdex(font);
		* std::vector<std::pair<uint32_t, float>> variationSettings;
		* for (size_t i = 0; i < ASystemFont_getAxisCount(font); ++i) {
		* variationSettings.push_back(std::make_pair(
		* ASystemFont_getAxisTag(font, i),
		* ASystemFont_getAxisValue(font, i)));
		* }
		* ASystemFont_close(font);
		*
		* // Use this font for your text rendering engine.
		*
		* </code>
		*
		* Available since API level 29.
		*/

		#ifndef ANDROID_SYSTEM_FONTS_H
		#define ANDROID_SYSTEM_FONTS_H

		#include <stdbool.h>
		#include <stddef.h>
		#include <sys/cdefs.h>

		/******************************************************************
		*
		* IMPORTANT NOTICE:
		*
		* This file is part of Android's set of stable system headers
		* exposed by the Android NDK (Native Development Kit).
		*
		* Third-party source AND binary code relies on the definitions
		* here to be FROZEN ON ALL UPCOMING PLATFORM RELEASES.
		*
		* - DO NOT MODIFY ENUMS (EXCEPT IF YOU ADD NEW 32-BIT VALUES)
		* - DO NOT MODIFY CONSTANTS OR FUNCTIONAL MACROS
		* - DO NOT CHANGE THE SIGNATURE OF FUNCTIONS IN ANY WAY
		* - DO NOT CHANGE THE LAYOUT OR SIZE OF STRUCTURES
		*/

		__BEGIN_DECLS

		#if __ANDROID_API__ >= 29

		enum {
		/** The minimum value fot the font weight value. */
		ASYSTEM_FONT_WEIGHT_MIN = 0,

		/** A font weight value for the thin weight. */
		ASYSTEM_FONT_WEIGHT_THIN = 100,

		/** A font weight value for the extra-light weight. */
		ASYSTEM_FONT_WEIGHT_EXTRA_LIGHT = 200,

		/** A font weight value for the light weight. */
		ASYSTEM_FONT_WEIGHT_LIGHT = 300,

		/** A font weight value for the normal weight. */
		ASYSTEM_FONT_WEIGHT_NORMAL = 400,

		/** A font weight value for the medium weight. */
		ASYSTEM_FONT_WEIGHT_MEDIUM = 500,

		/** A font weight value for the semi-bold weight. */
		ASYSTEM_FONT_WEIGHT_SEMI_BOLD = 600,

		/** A font weight value for the bold weight. */
		ASYSTEM_FONT_WEIGHT_BOLD = 700,

		/** A font weight value for the extra-bold weight. */
		ASYSTEM_FONT_WEIGHT_EXTRA_BOLD = 800,

		/** A font weight value for the black weight. */
		ASYSTEM_FONT_WEIGHT_BLACK = 900,

		/** The maximum value for the font weight value. */
		ASYSTEM_FONT_WEIGHT_MAX = 1000
		};

		/**
		* ASystemFontIterator provides access to the system font configuration.
		*
		* ASystemFontIterator is an iterator for all available system font settings.
		* This iterator is not a thread-safe object. Do not pass this iterator to other threads.
		*/
		struct ASystemFontIterator;

		/**
		* ASystemFont provides information of the single system font configuration.
		*/
		struct ASystemFont;

		/**
		* Create a system font iterator.
		*
		* Use ASystemFont_close() to close the iterator.
		*
		* \return a pointer for a newly allocated iterator, nullptr on failure.
		*/
		ASystemFontIterator* _Nullable ASystemFontIterator_open() __INTRODUCED_IN(29);

		/**
		* Close an opened system font iterator, freeing any related resources.
		*
		* \param a pointer of an iterator for the system fonts. Do nothing if NULL is passed.
		*/
		void ASystemFontIterator_close(ASystemFontIterator* _Nullable iterator) __INTRODUCED_IN(29);

		/**
		* Move to the next system font.
		*
		* \param iterator an iterator for the system fonts. Passing NULL is not allowed.
		* \return true if more system fonts are available, otherwise false.
		*/
		ASystemFont* _Nullable ASystemFontIterator_next(ASystemFontIterator* _Nonnull iterator) __INTRODUCED_IN(29);

		/**
		* Close an ASystemFont returned by ASystemFontIterator_next.
		*
		* \param font a font returned by ASystemFontIterator_next. Do nothing if NULL is passed.
		*/
		void ASystemFont_close(ASystemFont* _Nullable font) __INTRODUCED_IN(29);


		/**
		* Return an absolute path to the current font file.
		*
		* Here is a list of font formats returned by this method:
		* <ul>
		* <li>OpenType</li>
		* <li>OpenType Font Collection</li>
		* <li>TrueType</li>
		* <li>TrueType Collection</li>
		* </ul>
		* The file extension could be one of .otf, .ttf, .otc or .ttc.
		*
		* The font file returned is guaranteed to be opend with O_RDONLY.
		* Note that the returned pointer is valid until ASystemFont_close() is called for the given font.
		*
		* \param iterator an iterator for the system fonts. Passing NULL is not allowed.
		* \return a string of the font file path.
		*/
		const char* _Nonnull ASystemFont_getFontFilePath(const ASystemFont* _Nonnull font) __INTRODUCED_IN(29);

		/**
		* Return a weight value associated with the current font.
		*
		* The weight values are positive and less than or equal to 1000.
		* Here are pairs of the common names and their values.
		* <p>
		* <table>
		* <thead>
		* <tr>
		* <th align="center">Value</th>
		* <th align="center">Name</th>
		* <th align="center">NDK Definition</th>
		* </tr>
		* </thead>
		* <tbody>
		* <tr>
		* <td align="center">100</td>
		* <td align="center">Thin</td>
		* <td align="center">{@link ASYSTEM_FONT_WEIGHT_THIN}</td>
		* </tr>
		* <tr>
		* <td align="center">200</td>
		* <td align="center">Extra Light (Ultra Light)</td>
		* <td align="center">{@link ASYSTEM_FONT_WEIGHT_EXTRA_LIGHT}</td>
		* </tr>
		* <tr>
		* <td align="center">300</td>
		* <td align="center">Light</td>
		* <td align="center">{@link ASYSTEM_FONT_WEIGHT_LIGHT}</td>
		* </tr>
		* <tr>
		* <td align="center">400</td>
		* <td align="center">Normal (Regular)</td>
		* <td align="center">{@link ASYSTEM_FONT_WEIGHT_NORMAL}</td>
		* </tr>
		* <tr>
		* <td align="center">500</td>
		* <td align="center">Medium</td>
		* <td align="center">{@link ASYSTEM_FONT_WEIGHT_MEDIUM}</td>
		* </tr>
		* <tr>
		* <td align="center">600</td>
		* <td align="center">Semi Bold (Demi Bold)</td>
		* <td align="center">{@link ASYSTEM_FONT_WEIGHT_SEMI_BOLD}</td>
		* </tr>
		* <tr>
		* <td align="center">700</td>
		* <td align="center">Bold</td>
		* <td align="center">{@link ASYSTEM_FONT_WEIGHT_BOLD}</td>
		* </tr>
		* <tr>
		* <td align="center">800</td>
		* <td align="center">Extra Bold (Ultra Bold)</td>
		* <td align="center">{@link ASYSTEM_FONT_WEIGHT_EXTRA_BOLD}</td>
		* </tr>
		* <tr>
		* <td align="center">900</td>
		* <td align="center">Black (Heavy)</td>
		* <td align="center">{@link ASYSTEM_FONT_WEIGHT_BLACK}</td>
		* </tr>
		* </tbody>
		* </p>
		* Note that the weight value may fall in between above values, e.g. 250 weight.
		*
		* For more information about font weight, read [OpenType usWeightClass](https://docs.microsoft.com/en-us/typography/opentype/spec/os2#usweightclass)
		*
		* \param iterator an iterator for the system fonts. Passing NULL is not allowed.
		* \return a positive integer less than or equal to {@link ASYSTEM_FONT_MAX_WEIGHT} is returned.
		*/
		uint16_t ASystemFont_getWeight(const ASystemFont* _Nonnull font) __INTRODUCED_IN(29);

		/**
		* Return true if the current font is italic, otherwise returns false.
		*
		* \param iterator an iterator for the system fonts. Passing NULL is not allowed.
		* \return true if italic, otherwise false.
		*/
		bool ASystemFont_isItalic(const ASystemFont* _Nonnull font) __INTRODUCED_IN(29);

		/**
		* Return a IETF BCP47 compliant language tag associated with the current font.
		*
		* For information about IETF BCP47, read [Locale.forLanguageTag(java.lang.String)](https://developer.android.com/reference/java/util/Locale.html#forLanguageTag(java.lang.String)")
		*
		* Note that the returned pointer is valid until ASystemFont_close() is called.
		*
		* \param iterator an iterator for the system fonts. Passing NULL is not allowed.
		* \return a IETF BCP47 compliant langauge tag or nullptr if not available.
		*/
		const char* _Nullable ASystemFont_getLocale(const ASystemFont* _Nonnull font) __INTRODUCED_IN(29);

		/**
		* Return a font collection index value associated with the current font.
		*
		* In case the target font file is a font collection (e.g. .ttc or .otc), this
		* returns a non-negative value as an font offset in the collection. This
		* always returns 0 if the target font file is a regular font.
		*
		* \param iterator an iterator for the system fonts. Passing NULL is not allowed.
		* \return a font collection index.
		*/
		size_t ASystemFont_getCollectionIndex(const ASystemFont* _Nonnull font) __INTRODUCED_IN(29);

		/**
		* Return a count of font variation settings associated with the current font
		*
		* The font variation settings are provided as multiple tag-values pairs.
		*
		* For example, bold italic font may have following font variation settings:
		* 'wght' 700, 'slnt' -12
		* In this case, ASystemFont_getAxisCount returns 2 and ASystemFont_getAxisTag
		* and ASystemFont_getAxisValue will return following values.
		* <code>
		* ASystemFont* font = ASystemFontIterator_next(ite);
		*
		* // Returns the number of axes
		* ASystemFont_getAxisCount(font); // Returns 2
		*
		* // Returns the tag-value pair for the first axis.
		* ASystemFont_getAxisTag(font, 0); // Returns 'wght'(0x77676874)
		* ASystemFont_getAxisValue(font, 0); // Returns 700.0
		*
		* // Returns the tag-value pair for the second axis.
		* ASystemFont_getAxisTag(font, 1); // Returns 'slnt'(0x736c6e74)
		* ASystemFont_getAxisValue(font, 1); // Returns -12.0
		* </code>
		*
		* For more information about font variation settings, read [Font Variations Table](https://docs.microsoft.com/en-us/typography/opentype/spec/fvar)
		*
		* \param iterator an iterator for the system fonts. Passing NULL is not allowed.
		* \return a number of font variation settings.
		*/
		size_t ASystemFont_getAxisCount(const ASystemFont* _Nonnull font) __INTRODUCED_IN(29);


		/**
		* Return an OpenType axis tag associated with the current font.
		*
		* See ASystemFont_getAxisCount for more details.
		*
		* \param iterator an iterator for the system fonts. Passing NULL is not allowed.
		* \param an index to the font variation settings. Passing value larger than or
		* equal to {@link ASystemFont_getAxisCount} is not allowed.
		* \return an OpenType axis tag value for the given font variation setting.
		*/
		uint32_t ASystemFont_getAxisTag(const ASystemFont* _Nonnull font, uint32_t axisIndex)
		__INTRODUCED_IN(29);

		/**
		* Return an OpenType axis value associated with the current font.
		*
		* See ASystemFont_getAxisCount for more details.
		*
		* \param iterator an iterator for the system fonts. Passing NULL is not allowed.
		* \param an index to the font variation settings. Passing value larger than or
		* equal to {@link ASYstemFont_getAxisCount} is not allwed.
		* \return a float value for the given font variation setting.
		*/
		float ASystemFont_getAxisValue(const ASystemFont* _Nonnull font, uint32_t axisIndex)
		__INTRODUCED_IN(29);

		#endif // __ANDROID_API__ >= 29

		__END_DECLS

		#endif // ANDROID_SYSTEM_FONTS_H