這是文件是整個軟件的基礎文件。裏面主要定義了一個QGis這個類。類裏面定義了版本信息、各種基礎的類型例如：圖元類型、單位類型、幾何類型、基礎的數據類型、event類型。和一些基礎的函數，例如double轉字符串函數。下面對qgis.h進行了註釋。
/***************************************************************************
qgis.h - QGIS namespace
-------------------
begin : Sat Jun 30 2002
copyright : (C) 2002 by Gary E.Sherman
email : sherman at mrcc.com
***************************************************************************/
/***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#ifndef QGIS_H
#define QGIS_H
#include <QEvent>
#include <QString>
#include <QRegExp>
#include <QMetaType>
#include <QVariant>
#include <stdlib.h>
#include <cfloat>
#include <cmath>
#include <qnumeric.h>
/** \ingroup core
* The QGis class provides global constants for use throughout the application.
*/
class CORE_EXPORT QGis
{
public:
// Version constants
//
// Version string版本信息
static const char* QGIS_VERSION;
// Version number used for comparing versions using the "Check QGIS Version" function
static const int QGIS_VERSION_INT;
// Release name
static const char* QGIS_RELEASE_NAME;
// The development version
static const char* QGIS_DEV_VERSION;
// Enumerations
//
//! Used for symbology operations
// Feature types圖元的類型
enum WkbType
{
WKBUnknown = 0,
WKBPoint = 1,//點
WKBLineString,
WKBPolygon,
WKBMultiPoint,
WKBMultiLineString,
WKBMultiPolygon,
WKBNoGeometry = 100, //attributes only
WKBPoint25D = 0x80000001,
WKBLineString25D,
WKBPolygon25D,
WKBMultiPoint25D,
WKBMultiLineString25D,
WKBMultiPolygon25D,
};
static WkbType singleType( WkbType type )//圖元的多個類型對應的單類型
{
switch ( type )
{
case WKBMultiPoint: return WKBPoint;//例如這個，多個點自然是由很多單個點組成的。
case WKBMultiLineString: return WKBLineString;
case WKBMultiPolygon: return WKBPolygon;
case WKBMultiPoint25D: return WKBPoint25D;
case WKBMultiLineString25D: return WKBLineString25D;
case WKBMultiPolygon25D: return WKBPolygon25D;
default: return type;
}
}
static WkbType multiType( WkbType type )//圖元的單類型對應的多類型
{
switch ( type )
{
case WKBPoint: return WKBMultiPoint;
case WKBLineString: return WKBMultiLineString;
case WKBPolygon: return WKBMultiPolygon;
case WKBPoint25D: return WKBMultiPoint25D;
case WKBLineString25D: return WKBMultiLineString25D;
case WKBPolygon25D: return WKBMultiPolygon25D;
default: return type;
}
}
static WkbType flatType( WkbType type )//沒有用過這個函數，暫時不知道
{
switch ( type )
{
case WKBPoint25D: return WKBPoint;
case WKBLineString25D: return WKBLineString;
case WKBPolygon25D: return WKBPolygon;
case WKBMultiPoint25D: return WKBMultiPoint;
case WKBMultiLineString25D: return WKBMultiLineString;
case WKBMultiPolygon25D: return WKBMultiPolygon;
default: return type;
}
}
static bool isSingleType( WkbType type )//是不是單類型
{
switch ( flatType( type ) )
{
case WKBPoint:
case WKBLineString:
case WKBPolygon:
return true;
default:
return false;
}
}
static bool isMultiType( WkbType type )//是不是多類型
{
switch ( flatType( type ) )
{
case WKBMultiPoint:
case WKBMultiLineString:
case WKBMultiPolygon:
return true;
default:
return false;
}
}
static int wkbDimensions( WkbType type )//這個圖元對應的是幾維的
{
switch ( type )
{
case WKBUnknown: return 0;
case WKBNoGeometry: return 0;
case WKBPoint25D: return 3;//這種類型的是3維的
case WKBLineString25D: return 3;
case WKBPolygon25D: return 3;
case WKBMultiPoint25D: return 3;
case WKBMultiLineString25D: return 3;
case WKBMultiPolygon25D: return 3;
default: return 2;
}
}
enum GeometryType//幾何類型。圖元中包含幾何這個成員。
{
Point,
Line,
Polygon,//多邊形
UnknownGeometry,
NoGeometry
};
//! description strings for geometry types
static const char *vectorGeometryType( GeometryType type )//幾何類型的描述，這個函數應該不支持國際化吧
{
switch ( type )
{
case Point: return "Point";
case Line: return "Line";
case Polygon: return "Polygon";
case UnknownGeometry: return "Unknown geometry";
case NoGeometry: return "No geometry";
default: return "Invalid type";
}
}
//! description strings for feature types
static const char *featureType( WkbType type )//得到圖元的描述字符串
{
switch ( type )
{
case WKBUnknown: return "WKBUnknown";
case WKBPoint: return "WKBPoint";
case WKBLineString: return "WKBLineString";
case WKBPolygon: return "WKBPolygon";
case WKBMultiPoint: return "WKBMultiPoint";
case WKBMultiLineString: return "WKBMultiLineString";
case WKBMultiPolygon: return "WKBMultiPolygon";
case WKBNoGeometry: return "WKBNoGeometry";
case WKBPoint25D: return "WKBPoint25D";
case WKBLineString25D: return "WKBLineString25D";
case WKBPolygon25D: return "WKBPolygon25D";
case WKBMultiPoint25D: return "WKBMultiPoint25D";
case WKBMultiLineString25D: return "WKBMultiLineString25D";
case WKBMultiPolygon25D: return "WKBMultiPolygon25D";
default: return "invalid wkbtype";
}
}
/** Raster data types.
* This is modified and extended copy of GDALDataType.
*/
enum DataType//數據類型。相當重要。
{
/*! Unknown or unspecified type */ UnknownDataType = 0,
/*! Eight bit unsigned integer (quint8) */ Byte = 1,
/*! Sixteen bit unsigned integer (quint16) */ UInt16 = 2,
/*! Sixteen bit signed integer (qint16) */ Int16 = 3,
/*! Thirty two bit unsigned integer (quint32) */ UInt32 = 4,
/*! Thirty two bit signed integer (qint32) */ Int32 = 5,
/*! Thirty two bit floating point (float) */ Float32 = 6,
/*! Sixty four bit floating point (double) */ Float64 = 7,
/*! Complex Int16 */ CInt16 = 8,
/*! Complex Int32 */ CInt32 = 9,
/*! Complex Float32 */ CFloat32 = 10,
/*! Complex Float64 */ CFloat64 = 11,
/*! Color, alpha, red, green, blue, 4 bytes the same as
QImage::Format_ARGB32 */ ARGB32 = 12,
/*! Color, alpha, red, green, blue, 4 bytes the same as
QImage::Format_ARGB32_Premultiplied */ ARGB32_Premultiplied = 13
};
/** Map units that qgis supports
* @note that QGIS < 1.4 api had only Meters, Feet, Degrees and UnknownUnit
* @note and QGIS >1.8 returns to that
*/
enum UnitType//單位類型
{
Meters = 0,//米
Feet = 1,//英尺
Degrees = 2, //for 1.0 api backwards compatibility
UnknownUnit = 3,
// for [1.4;1.8] api compatibility
DecimalDegrees = 2, // was 2
DegreesMinutesSeconds = 2, // was 4
DegreesDecimalMinutes = 2, // was 5
NauticalMiles = 7
};
//! Provides the canonical name of the type value
// Added in version 2.0把對應的單位轉換爲可以顯示的字符串，內部的實現是通過查一個數組qgisUnitTypes[]
//來實現的。
static QString toLiteral( QGis::UnitType unit );
//! Converts from the canonical name to the type value
// Added in version 2.0把字符串轉換爲對應的單位類型。同樣是通過查找qgisUnitTypes[]實現的
static UnitType fromLiteral( QString literal, QGis::UnitType defaultType = UnknownUnit );
//! Provides translated version of the type value
// Added in version 2.0
static QString tr( QGis::UnitType unit );
//! Returns the conversion factor between the specified units
static double fromUnitToUnitFactor( QGis::UnitType fromUnit, QGis::UnitType toUnit );
//! User defined event types
enum UserEvent
{
// These first two are useful for threads to alert their parent data providers
//! The extents have been calculated by a provider of a layer
ProviderExtentCalcEvent = ( QEvent::User + 1 ),//計算完畢圖層的延展（顯示用的），可以簡單的認爲是縮放。
//! The row count has been calculated by a provider of a layer
ProviderCountCalcEvent//這裏耍了個小技巧，enum類型可以自動++。沒有用過這個event
};
/** Old search radius in % of canvas width
* @deprecated since 2.3, use DEFAULT_SEARCH_RADIUS_MM */
static const double DEFAULT_IDENTIFY_RADIUS;
/** Identify search radius in mm
* @note added in 2.3 */
static const double DEFAULT_SEARCH_RADIUS_MM;
//! Default threshold between map coordinates and device coordinates for map2pixel simplification
static const float DEFAULT_MAPTOPIXEL_THRESHOLD;
/** Default highlight color. The transparency is expected to only be applied to polygon
* fill. Lines and outlines are rendered opaque.
* @note added in 2.3 */
static const QColor DEFAULT_HIGHLIGHT_COLOR;
/** Default highlight buffer in mm.
* @note added in 2.3 */
static double DEFAULT_HIGHLIGHT_BUFFER_MM;
/** Default highlight line/outline minimum width in mm.
* @note added in 2.3 */
static double DEFAULT_HIGHLIGHT_MIN_WIDTH_MM;
private:
// String representation of unit types (set in qgis.cpp)
static const char *qgisUnitTypes[];
};
// hack to workaround warnings when casting void pointers
// retrieved from QLibrary::resolve to function pointers.
// It's assumed that this works on all systems supporting
// QLibrary
inline void ( *cast_to_fptr( void *p ) )()
{
union
{
void *p;
void ( *f )();
} u;
u.p = p;
return u.f;
}
//
// return a string representation of a double
//
inline QString qgsDoubleToString( const double &a )//把double類型轉換爲字符串
{
return QString::number( a, 'f', 17 ).remove( QRegExp( "\\.?0+$" ) );
}
//
// compare two doubles (but allow some difference)
//
inline bool qgsDoubleNear( double a, double b, double epsilon = 4 * DBL_EPSILON )
{
const double diff = a - b;
return diff > -epsilon && diff <= epsilon;
}
//
// compare two doubles using specified number of significant digits
//
inline bool qgsDoubleNearSig( double a, double b, int significantDigits = 10 )
{
// The most simple would be to print numbers as %.xe and compare as strings
// but that is probably too costly
// Then the fastest would be to set some bits directly, but little/big endian
// has to be considered (maybe TODO)
// Is there a better way?
int aexp, bexp;
double ar = frexp( a, &aexp );
double br = frexp( b, &bexp );
return aexp == bexp &&
qRound( ar * pow( 10.0, significantDigits ) ) == qRound( br * pow( 10.0, significantDigits ) ) ;
}
bool qgsVariantLessThan( const QVariant& lhs, const QVariant& rhs );
bool qgsVariantGreaterThan( const QVariant& lhs, const QVariant& rhs );
QString qgsVsiPrefix( QString path );
/** Allocates size bytes and returns a pointer to the allocated memory.
Works like C malloc() but prints debug message by QgsLogger if allocation fails.
@param size size in bytes
*/
void CORE_EXPORT *qgsMalloc( size_t size );
/** Allocates memory for an array of nmemb elements of size bytes each and returns
a pointer to the allocated memory. Works like C calloc() but prints debug message
by QgsLogger if allocation fails.
@param nmemb number of elements
@param size size of element in bytes
*/
void CORE_EXPORT *qgsCalloc( size_t nmemb, size_t size );
/** Frees the memory space pointed to by ptr. Works like C free().
@param ptr pointer to memory space
*/
void CORE_EXPORT qgsFree( void *ptr );
/** Wkt string that represents a geographic coord sys
* @note added in 1.8 to replace GEOWkt
*/
extern CORE_EXPORT const QString GEOWKT;
extern CORE_EXPORT const QString PROJECT_SCALES;
/** PROJ4 string that represents a geographic coord sys */
extern CORE_EXPORT const QString GEOPROJ4;
/** Magic number for a geographic coord sys in POSTGIS SRID */
const long GEOSRID = 4326;
/** Magic number for a geographic coord sys in QGIS srs.db tbl_srs.srs_id */
const long GEOCRS_ID = 3452;
/** Magic number for a geographic coord sys in EpsgCrsId ID format */
const long GEO_EPSG_CRS_ID = 4326;
/** Geographic coord sys from EPSG authority */
extern CORE_EXPORT const QString GEO_EPSG_CRS_AUTHID;
/** The length of the string "+proj=" */
const int PROJ_PREFIX_LEN = 6;
/** The length of the string "+ellps=" */
const int ELLPS_PREFIX_LEN = 7;
/** The length of the string "+lat_1=" */
const int LAT_PREFIX_LEN = 7;
/** Magick number that determines whether a projection crsid is a system (srs.db)
* or user (~/.qgis.qgis.db) defined projection. */
const int USER_CRS_START_ID = 100000;
//! Constant that holds the string representation for "No ellips/No CRS"
// Added in version 2.0
extern CORE_EXPORT const QString GEO_NONE;
//
// Constants for point symbols
//
/** Magic number that determines the minimum allowable point size for point symbols */
const double MINIMUM_POINT_SIZE = 0.1;
/** Magic number that determines the default point size for point symbols */
const double DEFAULT_POINT_SIZE = 2.0;
const double DEFAULT_LINE_WIDTH = 0.26;
/** default snapping tolerance for segments (@note added in 1.8) */
const double DEFAULT_SEGMENT_EPSILON = 1e-8;
typedef QMap<QString, QString> QgsStringMap;
/** qgssize is used instead of size_t, because size_t is stdlib type, unknown
* by SIP, and it would be hard to define size_t correctly in SIP.
* Currently used "unsigned long long" was introduced in C++11 (2011)
* but it was supported already before C++11 on common platforms.
* "unsigned long long int" gives syntax error in SIP.
* KEEP IN SYNC WITH qgssize defined in SIP! */
typedef unsigned long long qgssize;
#if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)) || defined(__clang__)
#define Q_NOWARN_DEPRECATED_PUSH \
_Pragma("GCC diagnostic push") \
_Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"")
#define Q_NOWARN_DEPRECATED_POP \
_Pragma("GCC diagnostic pop")
#elif defined(_MSC_VER)
#define Q_NOWARN_DEPRECATED_PUSH \
__pragma(warning(push)) \
__pragma(warning(disable:4996))
#define Q_NOWARN_DEPRECATED_POP \
__pragma(warning(pop))
#else
#define Q_NOWARN_DEPRECATED_PUSH
#define Q_NOWARN_DEPRECATED_POP
#endif
// FIXME: also in qgisinterface.h
#ifndef QGISEXTERN
#ifdef WIN32
# define QGISEXTERN extern "C" __declspec( dllexport )
# ifdef _MSC_VER
// do not warn about C bindings returing QString
# pragma warning(disable:4190)
# endif
#else
# define QGISEXTERN extern "C"
#endif
#endif
#endif