initial add.

FontSizeEstimator.h

+// -*- mode:objc -*-
+/*
+ **  FontSizeEstimator.h
+ **
+ **  Copyright (c) 2011
+ **
+ **  Author: George Nachman
+ **
+ **  Project: iTerm2
+ **
+ **  Description: Attempts to measure font metrics because the OS's metrics
+ **    are sometimes unreliable.
+ **
+ **  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.
+ **
+ **  This program is distributed in the hope that it will be useful,
+ **  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ **  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ **  GNU General Public License for more details.
+ **
+ **  You should have received a copy of the GNU General Public License
+ **  along with this program; if not, write to the Free Software
+ **  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+
+#import <Cocoa/Cocoa.h>
+
+
+@interface FontSizeEstimator : NSObject {
+    NSSize osBound;
+    NSSize size;
+    double baseline;
+}
+
+@property (nonatomic, assign) NSSize size;
+@property (nonatomic, assign) double baseline;
+
++ (id)fontSizeEstimatorForFont:(NSFont *)aFont;
+
+@end

FontSizeEstimator.m

+// -*- mode:objc -*-
+/*
+ **  FontSizeEstimator.h
+ **
+ **  Copyright (c) 2011
+ **
+ **  Author: George Nachman
+ **
+ **  Project: iTerm2
+ **
+ **  Description: Attempts to measure font metrics because the OS's metrics
+ **    are sometimes unreliable.
+ **
+ **  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.
+ **
+ **  This program is distributed in the hope that it will be useful,
+ **  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ **  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ **  GNU General Public License for more details.
+ **
+ **  You should have received a copy of the GNU General Public License
+ **  along with this program; if not, write to the Free Software
+ **  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#import "FontSizeEstimator.h"
+
+// Constants for converting RGB to luma.
+#define RED_COEFFICIENT    0.30
+#define GREEN_COEFFICIENT  0.59
+#define BLUE_COEFFICIENT   0.11
+
+static const double kBrightnessThreshold = 0.95;
+
+@implementation FontSizeEstimator
+
+@synthesize size;
+@synthesize baseline;
+
+static double Brightness(NSColor* c) {
+    const double r = [c redComponent];
+    const double g = [c greenComponent];
+    const double b = [c blueComponent];
+
+    return (RED_COEFFICIENT * r) + (GREEN_COEFFICIENT * g) + (BLUE_COEFFICIENT * b);
+}
+
+- (NSSize)osEstimate:(NSFont *)aFont
+{
+    if (!osBound.width) {
+        osBound = NSZeroSize;
+        NSMutableDictionary *dic = [NSMutableDictionary dictionary];
+        [dic setObject:aFont forKey:NSFontAttributeName];
+        for (unichar i = 'A'; i <= 'Z'; i++) {
+            NSString* s = [NSString stringWithCharacters:&i length:1];
+            NSSize charSize = [s sizeWithAttributes:dic];
+            osBound.width = MAX(size.width, charSize.width);
+            osBound.height = MAX(size.height, charSize.height);
+        }
+    }
+    
+    return osBound;
+}
+
+- (NSImage *)imageForString:(NSString*)s withFont:(NSFont*)aFont
+{
+    // TODO: sometimes ctx is null but I haven't caught it yet.
+    CGContextRef ctx = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
+    assert(ctx);
+    CGContextSetShouldAntialias(ctx, NO);
+    
+    NSSize osSize = [self osEstimate:aFont];
+    NSSize estimate = osSize;
+    estimate.width *= 4;
+    estimate.height *= 4;
+    NSImage *image = [[[NSImage alloc] initWithSize:NSMakeSize(estimate.width, estimate.height)] autorelease];
+    [image lockFocus];
+    
+    [[NSColor whiteColor] set];
+    NSRectFill(NSMakeRect(0, 0, estimate.width, estimate.height));
+    
+    NSDictionary *attrs = [NSDictionary dictionaryWithObjectsAndKeys:
+                           aFont, NSFontAttributeName,
+                           [NSColor blackColor], NSForegroundColorAttributeName,
+                           nil];
+    
+    NSAttributedString *str = [[NSAttributedString alloc] initWithString:s
+                                                              attributes:attrs];
+    [str drawWithRect:NSMakeRect(0,
+                                 osSize.height * 2,
+                                 osSize.width * 2,
+                                 osSize.height * 2)
+              options:0];
+    [image unlockFocus];
+        
+    return image;
+}
+
++ (double)xBoundOfImage:(NSImage *)i startingAt:(int)startAt dir:(int)dir
+{
+    int maxX = [i size].width;
+    int maxY = [i size].height;
+    int x;
+    [i lockFocus];
+    for (x = startAt; x >= 0 && x < maxX; x += dir) {
+        for (int y = 0; y < maxY; y++) {
+            NSColor *c = NSReadPixel(NSMakePoint(x, maxY - y - 1));
+            if (Brightness(c) < kBrightnessThreshold) {
+                [i unlockFocus];
+                return x;
+            }
+        }
+    }
+    [i unlockFocus];
+    return x;
+}
+
++ (double)yBoundOfImage:(NSImage *)i startingAt:(int)startAt dir:(int)dir
+{
+    int maxX = [i size].width;
+    int maxY = [i size].height;
+    int y;
+    [i lockFocus];
+    for (y = startAt; y >= 0 && y < maxY; y += dir) {
+        for (int x = 0; x < maxX; x++) {
+            NSColor *c = NSReadPixel(NSMakePoint(x, maxY - y - 1));
+            if (Brightness(c) < kBrightnessThreshold) {
+                [i unlockFocus];
+                return y;
+            }
+        }
+    }
+    [i unlockFocus];
+    return y;
+}
+
++ (void)dumpImage:(NSImage *)i
+{
+    [i lockFocus];
+    for (int y = [i size].height - 1; y >= 0; y--) {
+        unichar temp[1000];
+        int x;
+        for (x = 0; x < [i size].width; x++) {
+            NSColor *c = NSReadPixel(NSMakePoint(x, y));
+            //NSLog(@"%@ %lf", c, Brightness(c));
+            if (Brightness(c) < kBrightnessThreshold) {
+                temp[x] = '#';
+            } else {
+                temp[x] = ' ';
+            }
+        }
+        int n = [i size].height - 1 - y;
+        NSLog(@"%04d %@", n, [NSString stringWithCharacters:temp length:x]);
+    }
+    [i unlockFocus];
+}
+
+- (NSRect)boundsOfImage:(NSImage *)i
+{    
+    // [FontSizeEstimator dumpImage:i];
+    NSRect result = NSZeroRect;
+    result.origin.x = [FontSizeEstimator xBoundOfImage:i startingAt:0 dir:1];
+    result.size.width = [FontSizeEstimator xBoundOfImage:i startingAt:[i size].width-1 dir:-1] - result.origin.x + 1;
+    result.origin.y = [FontSizeEstimator yBoundOfImage:i startingAt:0 dir:1];
+    result.size.height = [FontSizeEstimator yBoundOfImage:i startingAt:[i size].height-1 dir:-1] - result.origin.y + 1;
+    return result;
+}
+
+- (id)initWithSize:(NSSize)s baseline:(double)b
+{
+    self = [super init];
+    if (self) {
+        size = s;
+        baseline = b;
+    }
+    return self;
+}
+
++ (id)fontSizeEstimatorForFont:(NSFont *)aFont
+{
+    FontSizeEstimator* fse = [[[FontSizeEstimator alloc] init] autorelease];
+    if (fse) {
+        // We get the upper bound of a character from the top of X
+        // We get the rightmost bound as the max of right(X) and right(x)
+        // We get the descender's height from bottom(y) - bottom(X)
+        NSImage *capXImage = [fse imageForString:@"X" withFont:aFont];
+        NSRect capXBounds = [fse boundsOfImage:capXImage];
+        
+        NSImage *lowXImage = [fse imageForString:@"x" withFont:aFont];
+        NSRect lowXBounds = [fse boundsOfImage:lowXImage];
+        
+        NSImage *lowYImage = [fse imageForString:@"y" withFont:aFont];
+        NSRect lowYBounds = [fse boundsOfImage:lowYImage];
+        
+        NSSize s;
+        double b;
+        double capXMaxX = capXBounds.origin.x + capXBounds.size.width;
+        double lowXMaxX = lowXBounds.origin.x + lowXBounds.size.width;
+        s.width = MAX(capXMaxX, lowXMaxX);
+        s.height = lowYBounds.origin.y + lowYBounds.size.height - capXBounds.origin.y;
+        double lowYMaxY = lowYBounds.origin.y + lowYBounds.size.height;
+        double capXmaxY = capXBounds.origin.y + capXBounds.size.height;
+        b = capXmaxY - lowYMaxY;
+        
+        // If the OS reports a larger size, use it.
+        NSMutableDictionary *dic = [NSMutableDictionary dictionary];
+        [dic setObject:aFont forKey:NSFontAttributeName];
+        s.height = MAX(s.height, ([aFont ascender] - [aFont descender]));
+        s.width = MAX(s.width, [@"X" sizeWithAttributes:dic].width);
+        
+        [fse setSize:s];
+        [fse setBaseline:b];
+    }    
+    return fse;
+}
+
+@end