RMProjection.m
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//
// RMProjection.m
// MapView
//
// Created by Joseph Gentle on 18/08/08.
// Copyright 2008 __MyCompanyName__. All rights reserved.
//
#import "proj_api.h"
#import "RMProjection.h"
NS_INLINE RMLatLong RMPixelPointAsLatLong(RMXYPoint xypoint) {
union _ {RMXYPoint xy; RMLatLong latLong;};
return ((union _ *)&xypoint)->latLong;
}
@implementation RMProjection
@synthesize internalProjection;
@synthesize bounds;
@synthesize projectionWrapsHorizontally;
- (id) initWithString: (NSString*)params InBounds: (RMXYRect) projBounds
{
if (![super init])
return nil;
internalProjection = pj_init_plus([params UTF8String]);
if (internalProjection == NULL)
{
NSLog(@"Unhandled error creating projection. String is %@", params);
[self dealloc];
return nil;
}
bounds = projBounds;
projectionWrapsHorizontally = YES;
return self;
}
- (id) initWithString: (NSString*)params
{
RMXYRect theBounds;
theBounds = RMXYMakeRect(0,0,0,0);
return [self initWithString:params InBounds:theBounds];
}
-(id)init
{
return [self initWithString:@"+proj=latlong +ellps=WGS84"];
}
-(void)dealloc
{
if (internalProjection)
pj_free(internalProjection);
[super dealloc];
}
- (RMXYPoint) wrapPointHorizontally: (RMXYPoint) aPoint
{
if (projectionWrapsHorizontally == NO
|| bounds.size.width == 0.0f || bounds.size.height == 0.0f)
return aPoint;
while (aPoint.x < bounds.origin.x)
aPoint.x += bounds.size.width;
while (aPoint.x > (bounds.origin.x + bounds.size.width))
aPoint.x -= bounds.size.width;
return aPoint;
}
-(RMXYPoint) constrainPointToBounds: (RMXYPoint) aPoint
{
if (bounds.size.width == 0.0f || bounds.size.height == 0.0f)
return aPoint;
[self wrapPointHorizontally:aPoint];
if (aPoint.y < bounds.origin.y)
aPoint.y = bounds.origin.y;
else if (aPoint.y > (bounds.origin.y + bounds.size.height))
aPoint.y = bounds.origin.y + bounds.size.height;
return aPoint;
}
- (RMXYPoint)latLongToPoint:(RMLatLong)aLatLong
{
projUV uv = {
aLatLong.longitude * DEG_TO_RAD,
aLatLong.latitude * DEG_TO_RAD
};
projUV result = pj_fwd(uv, internalProjection);
RMXYPoint result_point = {
result.u,
result.v,
};
return result_point;
}
- (RMLatLong)pointToLatLong:(RMXYPoint)aPoint
{
projUV uv = {
aPoint.x,
aPoint.y,
};
projUV result = pj_inv(uv, internalProjection);
RMLatLong result_coordinate = {
result.v * RAD_TO_DEG,
result.u * RAD_TO_DEG,
};
return result_coordinate;
}
static RMProjection* _google = nil;
static RMProjection* _latlong = nil;
static RMProjection* _osgb = nil;
+ (RMProjection*)googleProjection
{
if (_google)
{
return _google;
}
else
{
RMXYRect theBounds = RMXYMakeRect(-20037508.34, -20037508.34, 20037508.34 * 2, 20037508.34 * 2);
_google = [[RMProjection alloc] initWithString:@"+title= Google Mercator EPSG:900913\
+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs"
InBounds: theBounds];
return _google;
}
}
+ (RMProjection*)EPSGLatLong
{
if (_latlong)
{
return _latlong;
}
else
{
RMXYRect theBounds = RMXYMakeRect(-180, -90, 360, 180);
_latlong = [[RMProjection alloc] initWithString:@"+proj=latlong +ellps=WGS84" InBounds: theBounds];
return _latlong;
}
}
+(RMProjection*) OSGB
{
if (_osgb)
{
return _osgb;
}
else
{// OSGB36 and tmerc
// TODO: This should use the new initWithString:InBounds: method... but I don't know what the bounds are!
_osgb = [[RMProjection alloc] initWithString:@"+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.999601 +x_0=400000 +y_0=-100000 +ellps=airy +datum=OSGB36 +units=m +no_defs"];
_osgb.projectionWrapsHorizontally = NO;
return _osgb;
}
}
@end