GLTexture.h

//
//  NSImageGLTextureAdditions.h
//  SkryllePhoto
//
//  Created by Joachim Bengtsson on 2007-05-14.
//  Copyright 2007 Joachim Bengtsson. All rights reserved.
//

#import <Cocoa/Cocoa.h>
#import <OpenGL/gl.h>

@interface GLTexture : NSObject {
    GLuint texID;
    NSBitmapImageRep *cache;
    NSSize size;
}
/// Just takes ownership. NOTE: does not store size!
-(GLTexture*)initWithTexID:(GLuint)tid;
/// Creates a texture from src
-(GLTexture*)initWithNSImage:(NSImage*)src;

/// Does the expensive part of -[GLTexture useImage]. Can be called from any thread.
-(void)prepareCacheForImage:(NSImage*)src;

/// Converts src to an OpenGL texture.
/// @arg src may be nil if -[GLTexture prepareCacheForImage] has been called.
/// @note Calling this method invalidates the cache generated by -[GLTexture prepareCacheForImage]
/// @note Must be called from the same thread that the OpenGL context was created in.
-(GLTexture*)useImage:(NSImage*)src;

-(void)deleteTexture;

-(NSSize)size;

-(void)apply;
-(void)unapply;


// Private
-(void)makeOpenGLTextureOfInternalCache;

@end

@interface NSImage(NSImageGLTextureAdditions)
-(GLTexture*)glTexture;

-(NSSize)pixelSize;

+(NSImage*)imageWithContentsOfPath:(NSString*)path;
@end

GLTexture.m

//
//  NSImageGLTextureAdditions.m
//  SkryllePhoto
//
//  Created by Joachim Bengtsson on 2007-05-14.
//  Copyright 2007 Joachim Bengtsson. All rights reserved.
//

#import "GLTexture.h"
#import <OpenGL/glu.h>
#import "NCCommon.h"

@implementation GLTexture
-(GLTexture*)initWithTexID:(GLuint)tid;
{
    if(![super init]) return nil;
    cache = nil;
    texID = tid;
    return self;
}
-(GLTexture*)initWithNSImage:(NSImage*)src;
{
    if(![super init]) return nil;
    cache = nil;
    [self useImage:src];
    
    return self;
}

-(void)prepareCacheForImage:(NSImage*)src;
{
    [cache release];

    size = [src size];
    size.width = floorf( size.width );
    size.height = floorf( size.height );

    cache = [[NSBitmapImageRep alloc] 
            initWithBitmapDataPlanes: NULL
                          pixelsWide: size.width
                          pixelsHigh: size.height
                       bitsPerSample: 8
                     samplesPerPixel: 4
                            hasAlpha: YES
                            isPlanar: NO
                      colorSpaceName: NSDeviceRGBColorSpace
                        bitmapFormat: 0
                         bytesPerRow: 0
                        bitsPerPixel: 32];
    bzero( [cache bitmapData], size.height * [cache bytesPerRow] );
    NSGraphicsContext *ctx = [NSGraphicsContext graphicsContextWithBitmapImageRep: cache];
    NSGraphicsContext *old = [[NSGraphicsContext currentContext] retain];
    [NSGraphicsContext setCurrentContext: ctx];
    
    NSRect rect = { NSZeroPoint, size };
    [src drawInRect: rect fromRect: rect operation: NSCompositeSourceOver fraction: 1.0]; // 500 ms for 3mpx
    [NSGraphicsContext setCurrentContext: old]; [old release];
    
    
}
-(GLTexture*)useImage:(NSImage*)src;
{
    if(!cache)
        [self prepareCacheForImage:src];
    [self makeOpenGLTextureOfInternalCache];
    
    [cache release]; cache = nil;
    return self;
}

-(void)deleteTexture;
{
    if(texID)
        glDeleteTextures(1,&texID);
    texID = 0; // ensure it is zeroed for failure cases
}

-(void)dealloc;
{
    [self deleteTexture];
    [super dealloc];
}

-(NSSize)size;
{
    return size;
}

-(void)apply;
{
    glEnable(GL_TEXTURE_RECTANGLE_EXT);
    glBindTexture (GL_TEXTURE_RECTANGLE_EXT, texID);
}
-(void)unapply;
{
    glDisable(GL_TEXTURE_RECTANGLE_EXT);
}


-(void)makeOpenGLTextureOfInternalCache;
{    
    if(texID == 0)
        glGenTextures(1, &texID);
    glBindTexture( GL_TEXTURE_RECTANGLE_EXT, texID);
    glReportError();
    glTexParameteri( GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_WRAP_S, GL_CLAMP );
    glTexParameteri( GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_WRAP_T, GL_CLAMP );
    glTexParameteri( GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
    glTexParameteri( GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
    glReportError();
    glPixelStorei( GL_UNPACK_ALIGNMENT, 1 );
    glPixelStorei( GL_UNPACK_ROW_LENGTH, [cache bytesPerRow] / 4 );
    glReportError();
    
    glTexImage2D( GL_TEXTURE_RECTANGLE_EXT, 
                  0, 
                  GL_RGBA, 
                  size.width, 
                  size.height, 
                  0, 
                  GL_RGBA, 
                  GL_UNSIGNED_BYTE, 
                  [cache bitmapData] );
    glReportError();
}


-(NSString*)description;
{
    return sf(@"<GLTexture@%p wraps texid %d of size (%.2f, %.2f)>", self, texID, size.width, size.height);
}
@end

static unsigned int truncPowerOf2(unsigned int x)
{
    int i = 0;
    while (x = x>>1) i++;
    return (1<<i);
}

@implementation NSImage(NSImageGLTextureAdditions)
-(GLTexture*)glTexture;
{
    return [[[GLTexture alloc] initWithNSImage:self] autorelease];
}
-(NSSize)pixelSize;
{
    NSImageRep *r = [self bestRepresentationForDevice:nil];
    return NSMakeSize([r pixelsWide],[r pixelsHigh]);
}

+(NSImage*)imageWithContentsOfPath:(NSString*)path;
{
    return [[[NSImage alloc] initWithContentsOfFile:path] autorelease];
}
@end