Basic proof of concept is working.

sources/Metal/Support/iTermMetalClipView.h

+//
+//  iTermMetalClipView.h
+//  iTerm2SharedARC
+//
+//  Created by George Nachman on 10/2/17.
+//
+
+#import <Cocoa/Cocoa.h>
+
+@class MTKView;
+
+@interface iTermMetalClipView : NSClipView
+
+@property (nonatomic, weak) MTKView *metalView;
+
+@end

sources/Metal/Support/iTermMetalClipView.m

+//
+//  iTermMetalClipView.m
+//  iTerm2SharedARC
+//
+//  Created by George Nachman on 10/2/17.
+//
+
+#import "iTermMetalClipView.h"
+
+#import <MetalKit/MetalKit.h>
+
+@implementation iTermMetalClipView
+
+- (instancetype)initWithFrame:(NSRect)frameRect {
+    self = [super initWithFrame:frameRect];
+    if (self) {
+        self.copiesOnScroll = NO;
+    }
+    return self;
+}
+/*
+- (void)scrollToPoint:(NSPoint)newOrigin {
+    [super scrollToPoint:newOrigin];
+    NSRect frame = _metalView.frame;
+    frame.origin.y = newOrigin.y;
+    _metalView.frame = frame;
+}
+*/
+@end
+

sources/Metal/iTermMetalDriver.h

+#import "VT100GridTypes.h"
+
+#import "iTermCursor.h"
+#include "iTermMetalGlyphKey.h"
+
+@import MetalKit;
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface iTermMetalCursorInfo : NSObject
+@property (nonatomic) BOOL cursorVisible;
+@property (nonatomic) VT100GridCoord coord;
+@property (nonatomic) ITermCursorType type;
+@property (nonatomic, strong) NSColor *cursorColor;
+@end
+
+@protocol iTermMetalDriverDataSourcePerFrameState<NSObject>
+
+- (void)metalGetGlyphKeys:(iTermMetalGlyphKey *)glyphKeys
+               attributes:(iTermMetalGlyphAttributes *)attributes
+               background:(vector_float4 *)backgrounds
+                      row:(int)row
+                    width:(int)width;
+
+- (nullable iTermMetalCursorInfo *)metalDriverCursorInfo;
+
+- (NSImage *)metalImageForGlyphKey:(iTermMetalGlyphKey *)glyphKey
+                              size:(CGSize)size
+                             scale:(CGFloat)scale;
+@end
+
+@protocol iTermMetalDriverDataSource<NSObject>
+
+- (nullable id<iTermMetalDriverDataSourcePerFrameState>)metalDriverWillBeginDrawingFrame;
+
+@end
+
+// Our platform independent render class
+NS_CLASS_AVAILABLE(10_11, NA)
+@interface iTermMetalDriver : NSObject<MTKViewDelegate>
+
+@property (nullable, nonatomic, weak) id<iTermMetalDriverDataSource> dataSource;
+
+- (nullable instancetype)initWithMetalKitView:(nonnull MTKView *)mtkView;
+- (void)setCellSize:(CGSize)cellSize gridSize:(VT100GridSize)gridSize scale:(CGFloat)scale;
+
+@end
+
+NS_ASSUME_NONNULL_END
+

sources/NSColor+iTerm.h

@@ -7,6 +7,7 @@
 //
 #import <Cocoa/Cocoa.h>
+#import <simd/simd.h>
 // Keys of -dictionaryValue. Use -[NSDictionary colorVaue] to convert to color.
 extern NSString *const kEncodedColorDictionaryRedComponent;
@@ -19,6 +20,11 @@ extern NSString *const kEncodedColorDictionaryColorSpace;  // Optional, defaults
 extern NSString *const kEncodedColorDictionarySRGBColorSpace;
 extern NSString *const kEncodedColorDictionaryCalibratedColorSpace;
+static float SIMDPerceivedBrightness(vector_float4 x) {
+    static const vector_float4 y = (vector_float4){ 0.30, 0.59, 0.11, 0 };
+    return simd_dot(x, y);
+}
+
 @interface NSColor (iTerm)
 @property(nonatomic, readonly) CGFloat perceivedBrightness;

sources/PTYFontInfo.h

@@ -22,6 +22,15 @@
 + (PTYFontInfo *)fontInfoWithFont:(NSFont *)font;
++ (PTYFontInfo *)fontForAsciiCharacter:(BOOL)isAscii
+                             asciiFont:(PTYFontInfo *)asciiFont
+                          nonAsciiFont:(PTYFontInfo *)nonAsciiFont
+                           useBoldFont:(BOOL)useBoldFont
+                         useItalicFont:(BOOL)useItalicFont
+                      usesNonAsciiFont:(BOOL)useNonAsciiFont
+                            renderBold:(BOOL *)renderBold
+                          renderItalic:(BOOL *)renderItalic;
+
 // Returns a new autorelased PTYFontInfo with a bold version of this font (or
 // nil if none is available).
 - (PTYFontInfo *)computedBoldVersion;

sources/PTYFontInfo.m

@@ -73,6 +73,54 @@
 @synthesize boldVersion = boldVersion_;
 @synthesize italicVersion = italicVersion_;
++ (PTYFontInfo *)fontForAsciiCharacter:(BOOL)isAscii
+                             asciiFont:(PTYFontInfo *)asciiFont
+                          nonAsciiFont:(PTYFontInfo *)nonAsciiFont
+                           useBoldFont:(BOOL)useBoldFont
+                         useItalicFont:(BOOL)useItalicFont
+                      usesNonAsciiFont:(BOOL)useNonAsciiFont
+                            renderBold:(BOOL *)renderBold
+                          renderItalic:(BOOL *)renderItalic {
+    BOOL isBold = *renderBold && useBoldFont;
+    BOOL isItalic = *renderItalic && useItalicFont;
+    *renderBold = NO;
+    *renderItalic = NO;
+    PTYFontInfo *theFont;
+    BOOL usePrimary = !useNonAsciiFont || isAscii;
+
+    PTYFontInfo *rootFontInfo = usePrimary ? asciiFont : nonAsciiFont;
+    theFont = rootFontInfo;
+
+    if (isBold && isItalic) {
+        theFont = rootFontInfo.boldItalicVersion;
+        if (!theFont && rootFontInfo.boldVersion) {
+            theFont = rootFontInfo.boldVersion;
+            *renderItalic = YES;
+        } else if (!theFont && rootFontInfo.italicVersion) {
+            theFont = rootFontInfo.italicVersion;
+            *renderBold = YES;
+        } else if (!theFont) {
+            theFont = rootFontInfo;
+            *renderBold = YES;
+            *renderItalic = YES;
+        }
+    } else if (isBold) {
+        theFont = rootFontInfo.boldVersion;
+        if (!theFont) {
+            theFont = rootFontInfo;
+            *renderBold = YES;
+        }
+    } else if (isItalic) {
+        theFont = rootFontInfo.italicVersion;
+        if (!theFont) {
+            theFont = rootFontInfo;
+            *renderItalic = YES;
+        }
+    }
+
+    return theFont;
+}
+
 + (PTYFontInfo *)fontInfoWithFont:(NSFont *)font {
     PTYFontInfo *fontInfo = [[[PTYFontInfo alloc] init] autorelease];
     fontInfo.font = font;

sources/PTYSession.m

@@ -23,6 +23,8 @@
 #import "iTermInitialDirectory.h"
 #import "iTermKeyBindingMgr.h"
 #import "iTermKeyLabels.h"
+#import "iTermMetalGlue.h"
+#import "iTermMetalDriver.h"
 #import "iTermMenuOpener.h"
 #import "iTermMouseCursor.h"
 #import "iTermPasteHelper.h"
@@ -462,6 +464,8 @@ static const NSUInteger kMaxHosts = 100;
     long long _statusChangedAbsLine;
     iTermUpdateCadenceController *_cadenceController;
+
+    iTermMetalGlue *_metalGlue;
 }
 + (void)registerSessionInArrangement:(NSDictionary *)arrangement {
@@ -545,6 +549,8 @@ static const NSUInteger kMaxHosts = 100;
         _customEscapeSequenceNotifications = [[NSMutableDictionary alloc] init];
         _statusChangedAbsLine = -1;
+        _metalGlue = [[iTermMetalGlue alloc] init];
+        _metalGlue.screen = _screen;
         [[NSNotificationCenter defaultCenter] addObserver:self
                                                  selector:@selector(coprocessChanged)
@@ -607,6 +613,7 @@ ITERM_WEAKLY_REFERENCEABLE
 - (void)iterm_dealloc {
     [_view release];
+    [_metalGlue release];
     [self stopTailFind];  // This frees the substring in the tail find context, if needed.
     _shell.delegate = nil;
     dispatch_release(_executionSemaphore);
@@ -1300,6 +1307,9 @@ ITERM_WEAKLY_REFERENCEABLE
     NSDictionary *liveArrangement = arrangement[SESSION_ARRANGEMENT_LIVE_SESSION];
     if (liveArrangement) {
         SessionView *liveView = [[[SessionView alloc] initWithFrame:sessionView.frame] autorelease];
+        if (@available(macOS 10.11, *)) {
+            liveView.driver.dataSource = aSession->_metalGlue;
+        }
         [delegate addHiddenLiveView:liveView];
         aSession.liveSession = [self sessionFromArrangement:liveArrangement
                                                      inView:liveView
@@ -1351,6 +1361,9 @@ ITERM_WEAKLY_REFERENCEABLE
     // Allocate the root per-session view.
     if (!_view) {
         self.view = [[[SessionView alloc] initWithFrame:NSMakeRect(0, 0, aRect.size.width, aRect.size.height)] autorelease];
+        if (@available(macOS 10.11, *)) {
+            self.view.driver.dataSource = _metalGlue;
+        }
         [[_view findViewController] setDelegate:self];
     }
@@ -1362,6 +1375,7 @@ ITERM_WEAKLY_REFERENCEABLE
     _textview = [[PTYTextView alloc] initWithFrame: NSMakeRect(0, [iTermAdvancedSettingsModel terminalVMargin], aSize.width, aSize.height)
                                           colorMap:_colorMap];
+    _metalGlue.textView = _textview;
     _colorMap.dimOnlyText = [iTermPreferences boolForKey:kPreferenceKeyDimOnlyText];
     [_textview setAutoresizingMask: NSViewWidthSizable | NSViewHeightSizable];
     [_textview setFont:[ITAddressBookMgr fontWithDesc:[_profile objectForKey:KEY_NORMAL_FONT]]
@@ -1412,6 +1426,13 @@ ITERM_WEAKLY_REFERENCEABLE
     _newOutput = NO;
     [_view updateScrollViewFrame];
     [self useTransparencyDidChange];
+
+    if (@available(macOS 10.11, *)) {
+        [_view.driver setCellSize:CGSizeMake(_textview.charWidth, _textview.lineHeight)
+                         gridSize:_screen.currentGrid.size
+                            scale:_view.window.screen.backingScaleFactor];
+    }
+
     return YES;
 }
@@ -1500,6 +1521,11 @@ ITERM_WEAKLY_REFERENCEABLE
         [_delegate sessionBelongsToVisibleTab]) {
         [self beginTailFind];
     }
+    if (@available(macOS 10.11, *)) {
+        [_view.driver setCellSize:CGSizeMake(_textview.charWidth, _textview.lineHeight)
+                         gridSize:_screen.currentGrid.size
+                            scale:_view.window.screen.backingScaleFactor];
+    }
 }
 - (void)setSplitSelectionMode:(SplitSelectionMode)mode move:(BOOL)move {
@@ -1906,6 +1932,7 @@ ITERM_WEAKLY_REFERENCEABLE
     [_textview setDelegate:nil];
     [_textview removeFromSuperview];
     _textview = nil;
+    _metalGlue.textView = nil;
 }
 - (void)jumpToLocationWhereCurrentStatusChanged {
@@ -3688,6 +3715,9 @@ ITERM_WEAKLY_REFERENCEABLE
     [_view autorelease];
     _view = [newView retain];
     newView.delegate = self;
+    if (@available(macOS 10.11, *)) {
+        newView.driver.dataSource = _metalGlue;
+    }
     [newView updateTitleFrame];
     [[_view findViewController] setDelegate:self];
 }
@@ -6223,6 +6253,11 @@ ITERM_WEAKLY_REFERENCEABLE
         [self notifyTmuxFontChange];
     }
     [_view updateScrollViewFrame];
+    if (@available(macOS 10.11, *)) {
+        [_view.driver setCellSize:CGSizeMake(_textview.charWidth, _textview.lineHeight)
+                         gridSize:_screen.currentGrid.size
+                            scale:_view.window.screen.backingScaleFactor];
+}
 }
 - (BOOL)textViewHasBackgroundImage {
@@ -8996,6 +9031,14 @@ ITERM_WEAKLY_REFERENCEABLE
     [self.textview.window makeFirstResponder:self.textview];
 }
+- (void)sessionViewDidChangeWindow {
+    if (@available(macOS 10.11, *)) {
+        [_view.driver setCellSize:CGSizeMake(_textview.charWidth, _textview.lineHeight)
+                         gridSize:_screen.currentGrid.size
+                            scale:_view.window.screen.backingScaleFactor];
+    }
+}
+
 #pragma mark - iTermCoprocessDelegate
 - (void)coprocess:(Coprocess *)coprocess didTerminateWithErrorOutput:(NSString *)errors {
@@ -9251,4 +9294,5 @@ ITERM_WEAKLY_REFERENCEABLE
     return response;
 }
+
 @end

sources/PTYTextView.h

@@ -272,6 +272,9 @@ typedef NS_ENUM(NSInteger, PTYTextViewSelectionExtensionUnit) {
 @property(nonatomic, readonly) NSFont *font;
 @property(nonatomic, readonly) NSFont *nonAsciiFont;
+@property(nonatomic, readonly) PTYFontInfo *primaryFont;
+@property(nonatomic, readonly) PTYFontInfo *secondaryFont;  // non-ascii font, only used if self.useNonAsciiFont is set.
+
 // Returns the non-ascii font, even if it's not being used.
 @property(nonatomic, readonly) NSFont *nonAsciiFontEvenIfNotUsed;
@@ -324,6 +327,11 @@ typedef void (^PTYTextViewDrawingHookBlock)(iTermTextDrawingHelper *);
 // Lines that are currently visible on the screen.
 @property(nonatomic, readonly) VT100GridRange rangeOfVisibleLines;
+// Helps drawing text and background.
+@property (nonatomic, readonly) iTermTextDrawingHelper *drawingHelper;
+
+@property (nonatomic, readonly) double transparencyAlpha;
+
 // Returns the size of a cell for a given font. hspace and vspace are multipliers and the width
 // and height.
 + (NSSize)charSizeForFont:(NSFont*)aFont
@@ -488,7 +496,7 @@ typedef void (^PTYTextViewDrawingHookBlock)(iTermTextDrawingHelper *);
                          suffix:(NSString *)suffix;
 - (PTYFontInfo*)getFontForChar:(UniChar)ch
-                     isComplex:(BOOL)complex
+                     isComplex:(BOOL)isComplex
                     renderBold:(BOOL*)renderBold
                   renderItalic:(BOOL*)renderItalic;

sources/PTYTextView.m

@@ -156,9 +156,6 @@ static const int kDragThreshold = 3;
     NSDictionary *_markedTextAttributes;
-    PTYFontInfo *_primaryFont;
-    PTYFontInfo *_secondaryFont;  // non-ascii font, only used if self.useNonAsciiFont is set.
-
     BOOL _mouseDown;
     BOOL _mouseDragged;
     BOOL _mouseDownOnSelection;
@@ -306,7 +303,11 @@ static const int kDragThreshold = 3;
                                                  selector:@selector(imageDidLoad:)
                                                      name:iTermImageDidLoad
                                                    object:nil];
-        
+        [[NSNotificationCenter defaultCenter] addObserver:self
+                                                 selector:@selector(boundsDidChange:)
+                                                     name:NSViewBoundsDidChangeNotification
+                                                   object:nil];
+
         _semanticHistoryController = [[iTermSemanticHistoryController alloc] init];
         _semanticHistoryController.delegate = self;
         _semanticHistoryDragged = NO;
@@ -349,6 +350,24 @@ static const int kDragThreshold = 3;
     return self;
 }
+- (void)setNeedsDisplay:(BOOL)needsDisplay {
+    [super setNeedsDisplay:needsDisplay];
+    if (needsDisplay) {
+        [_delegate textViewNeedsDisplayInRect:self.bounds];
+    }
+}
+
+- (void)setNeedsDisplayInRect:(NSRect)invalidRect {
+    [super setNeedsDisplayInRect:invalidRect];
+    [_delegate textViewNeedsDisplayInRect:invalidRect];
+}
+
+- (void)boundsDidChange:(NSNotification *)notification {
+    if (notification.object == self.enclosingScrollView.contentView) {
+        NSLog(@"Bounds changed %@", NSStringFromRect(self.enclosingScrollView.contentView.bounds));
+    }
+}
+
 - (void)removeAllTrackingAreas {
     while (self.trackingAreas.count) {
         [self removeTrackingArea:self.trackingAreas[0]];
@@ -1049,6 +1068,56 @@ static const int kDragThreshold = 3;
     return _primaryFont.underlineOffset;
 }
+- (iTermTextDrawingHelper *)drawingHelper {
+    // Try to use a saved grid if one is available. If it succeeds, that implies that the cursor was
+    // recently hidden and what we're drawing is how the screen looked just before the cursor was
+    // hidden. Therefore, we'll temporarily show the cursor, but we'll need to restore cursorVisible's
+    // value when we're done.
+    if ([_dataSource setUseSavedGridIfAvailable:YES]) {
+        _drawingHelper.cursorVisible = YES;
+    }
+
+    _drawingHelper.showStripes = (_showStripesWhenBroadcastingInput &&
+                                  [_delegate textViewSessionIsBroadcastingInput]);
+    _drawingHelper.cursorBlinking = [self isCursorBlinking];
+    _drawingHelper.excess = [self excess];
+    _drawingHelper.selection = _selection;
+    _drawingHelper.ambiguousIsDoubleWidth = [_delegate textViewAmbiguousWidthCharsAreDoubleWidth];
+    _drawingHelper.normalization = [_delegate textViewUnicodeNormalizationForm];
+    _drawingHelper.hasBackgroundImage = [_delegate textViewHasBackgroundImage];
+    _drawingHelper.cursorGuideColor = [_delegate textViewCursorGuideColor];
+    _drawingHelper.gridSize = VT100GridSizeMake(_dataSource.width, _dataSource.height);
+    _drawingHelper.numberOfLines = _dataSource.numberOfLines;
+    _drawingHelper.cursorCoord = VT100GridCoordMake(_dataSource.cursorX - 1,
+                                                    _dataSource.cursorY - 1);
+    _drawingHelper.totalScrollbackOverflow = [_dataSource totalScrollbackOverflow];
+    _drawingHelper.numberOfScrollbackLines = [_dataSource numberOfScrollbackLines];
+    _drawingHelper.reverseVideo = [[_dataSource terminal] reverseVideo];
+    _drawingHelper.textViewIsActiveSession = [self.delegate textViewIsActiveSession];
+    _drawingHelper.isInKeyWindow = [self isInKeyWindow];
+    // Draw the cursor filled in when we're inactive if there's a popup open or key focus was stolen.
+    _drawingHelper.shouldDrawFilledInCursor = ([self.delegate textViewShouldDrawFilledInCursor] || _keyFocusStolenCount);
+    _drawingHelper.isFrontTextView = (self == [[iTermController sharedInstance] frontTextView]);
+    _drawingHelper.transparencyAlpha = [self transparencyAlpha];
+    _drawingHelper.now = [NSDate timeIntervalSinceReferenceDate];
+    _drawingHelper.drawMarkIndicators = [_delegate textViewShouldShowMarkIndicators];
+    _drawingHelper.thinStrokes = _thinStrokes;
+    _drawingHelper.showSearchingCursor = _showSearchingCursor;
+    _drawingHelper.baselineOffset = [self minimumBaselineOffset];
+    _drawingHelper.underlineOffset = [self minimumUnderlineOffset];
+    _drawingHelper.boldAllowed = _useBoldFont;
+    _drawingHelper.unicodeVersion = [_delegate textViewUnicodeVersion];
+    _drawingHelper.asciiLigatures = _primaryFont.hasDefaultLigatures || _asciiLigatures;
+    _drawingHelper.nonAsciiLigatures = _secondaryFont.hasDefaultLigatures || _nonAsciiLigatures;
+    _drawingHelper.copyMode = _delegate.textViewCopyMode;
+    _drawingHelper.copyModeSelecting = _delegate.textViewCopyModeSelecting;
+    _drawingHelper.copyModeCursorCoord = _delegate.textViewCopyModeCursorCoord;
+    _drawingHelper.passwordInput = _delegate.textViewPasswordInput;
+
+    return _drawingHelper;
+}
+
+/*
 - (void)drawRect:(NSRect)rect {
     if (_dataSource.width <= 0) {
         ITCriticalError(_dataSource.width < 0, @"Negative datasource width of %@", @(_dataSource.width));
@@ -1136,6 +1205,7 @@ static const int kDragThreshold = 3;
     [_dataSource setUseSavedGridIfAvailable:NO];
     _drawingHelper.cursorVisible = savedCursorVisible;
 }
+*/
 - (BOOL)getAndResetDrawingAnimatedImageFlag {
     BOOL result = _drawingHelper.animated;
@@ -5794,47 +5864,17 @@ static double EuclideanDistance(NSPoint p1, NSPoint p2) {
 }
 - (PTYFontInfo *)getFontForChar:(UniChar)ch
-                      isComplex:(BOOL)complex
+                      isComplex:(BOOL)isComplex
                      renderBold:(BOOL *)renderBold
                    renderItalic:(BOOL *)renderItalic {
-    BOOL isBold = *renderBold && _useBoldFont;
-    BOOL isItalic = *renderItalic && _useItalicFont;
-    *renderBold = NO;
-    *renderItalic = NO;
-    PTYFontInfo* theFont;
-    BOOL usePrimary = !_useNonAsciiFont || (!complex && (ch < 128));
-
-    PTYFontInfo *rootFontInfo = usePrimary ? _primaryFont : _secondaryFont;
-    theFont = rootFontInfo;
-
-    if (isBold && isItalic) {
-        theFont = rootFontInfo.boldItalicVersion;
-        if (!theFont && rootFontInfo.boldVersion) {
-            theFont = rootFontInfo.boldVersion;
-            *renderItalic = YES;
-        } else if (!theFont && rootFontInfo.italicVersion) {
-            theFont = rootFontInfo.italicVersion;
-            *renderBold = YES;
-        } else if (!theFont) {
-            theFont = rootFontInfo;
-            *renderBold = YES;
-            *renderItalic = YES;
-        }
-    } else if (isBold) {
-        theFont = rootFontInfo.boldVersion;
-        if (!theFont) {
-            theFont = rootFontInfo;
-            *renderBold = YES;
-        }
-    } else if (isItalic) {
-        theFont = rootFontInfo.italicVersion;
-        if (!theFont) {
-            theFont = rootFontInfo;
-            *renderItalic = YES;
-        }
-    }
-
-    return theFont;
+    return [PTYFontInfo fontForAsciiCharacter:(!isComplex && (ch < 128))
+                                    asciiFont:_primaryFont
+                                 nonAsciiFont:_secondaryFont
+                                  useBoldFont:_useBoldFont
+                                useItalicFont:_useItalicFont
+                             usesNonAsciiFont:_useNonAsciiFont
+                                   renderBold:renderBold
+                                 renderItalic:renderItalic];
 }
 #pragma mark - Private methods
@@ -5989,10 +6029,10 @@ static double EuclideanDistance(NSPoint p1, NSPoint p2) {
 }
 - (PTYCharType)classifyChar:(unichar)ch
-                  isComplex:(BOOL)complex
+                  isComplex:(BOOL)isComplex
 {
-    NSString* aString = CharToStr(ch, complex);
-    UTF32Char longChar = CharToLongChar(ch, complex);
+    NSString* aString = CharToStr(ch, isComplex);
+    UTF32Char longChar = CharToLongChar(ch, isComplex);
     if (longChar == DWC_RIGHT || longChar == DWC_SKIP) {
         return CHARTYPE_DW_FILLER;
@@ -6011,10 +6051,10 @@ static double EuclideanDistance(NSPoint p1, NSPoint p2) {
 }
 - (BOOL)shouldSelectCharForWord:(unichar)ch
-                      isComplex:(BOOL)complex
+                      isComplex:(BOOL)isComplex
                 selectWordChars:(BOOL)selectWordChars
 {
-    switch ([self classifyChar:ch isComplex:complex]) {
+    switch ([self classifyChar:ch isComplex:isComplex]) {
         case CHARTYPE_WHITESPACE:
             return !selectWordChars;
             break;
@@ -7074,11 +7114,11 @@ static double EuclideanDistance(NSPoint p1, NSPoint p2) {
 }
 - (PTYFontInfo *)drawingHelperFontForChar:(UniChar)ch
-                                isComplex:(BOOL)complex
+                                isComplex:(BOOL)isComplex
                                renderBold:(BOOL *)renderBold
                              renderItalic:(BOOL *)renderItalic {
     return [self getFontForChar:ch
-                      isComplex:complex
+                      isComplex:isComplex
                      renderBold:renderBold
                    renderItalic:renderItalic];
 }

sources/ProfileModel.h

@@ -40,7 +40,7 @@ typedef struct {
     SEL alternateSelector;         // opt+click
     SEL openAllSelector;           // open all bookmarks
     SEL alternateOpenAllSelector;  // opt+open all bookmarks
-    id target;                     // receiver of selector
+    void *target;                  // receiver of selector (actually an __unsafe_unretained id)
 } JournalParams;
 @interface ProfileModel : NSObject {

sources/SessionView.h

@@ -33,6 +33,7 @@
 #import "SplitSelectionView.h"
 @class iTermAnnouncementViewController;
+@class iTermMetalDriver;
 @class PTYSession;
 @class SplitSelectionView;
 @class SessionTitleView;
@@ -113,6 +114,9 @@
 // Make the textview the first responder
 - (void)sessionViewBecomeFirstResponder;
+// Current window changed.
+- (void)sessionViewDidChangeWindow;
+
 @end
 @interface SessionView : NSView <SessionTitleViewDelegate>
@@ -125,6 +129,7 @@
 @property(nonatomic, assign) id<iTermSessionViewDelegate> delegate;
 @property(nonatomic, readonly) PTYScrollView *scrollview;
 @property(nonatomic, assign) BOOL useSubviewWithLayer;
+@property(nonatomic, readonly) iTermMetalDriver *driver NS_AVAILABLE_MAC(10_11);
 + (double)titleHeight;
 + (NSDate*)lastResizeDate;

sources/SessionView.m

@@ -5,6 +5,7 @@
 #import "FutureMethods.h"
 #import "iTermAdvancedSettingsModel.h"
 #import "iTermAnnouncementViewController.h"
+#import "iTermMetalClipView.h"
 #import "iTermPreferences.h"
 #import "NSView+iTerm.h"
 #import "MovePaneController.h"
@@ -15,6 +16,9 @@
 #import "PTYTextView.h"
 #import "SessionTitleView.h"
 #import "SplitSelectionView.h"
+#import "iTermMetalDriver.h"
+
+#import <MetalKit/MetalKit.h>
 static int nextViewId;
 static const double kTitleHeight = 22;
@@ -82,6 +86,9 @@ static NSDate* lastResizeDate_;
     NSView *_hoverURLView;
     NSTextField *_hoverURLTextField;
+
+    iTermMetalDriver *_driver NS_AVAILABLE_MAC(10_11);
+    MTKView *_metalView NS_AVAILABLE_MAC(10_11);
 }
 + (double)titleHeight {
@@ -118,20 +125,36 @@ static NSDate* lastResizeDate_;
         // Assign a globally unique view ID.
         _viewId = nextViewId++;
-        // Allocate a scrollview
         _scrollview = [[PTYScrollView alloc] initWithFrame:NSMakeRect(0,
                                                                       0,
                                                                       aRect.size.width,
                                                                       aRect.size.height)
                                        hasVerticalScroller:NO];
+
+        // Add a metal view
+        if (@available(macOS 10.11, *)) {
+            _metalView = [[MTKView alloc] initWithFrame:_scrollview.contentView.frame
+                                                 device:MTLCreateSystemDefaultDevice()];
+            [self addSubview:_metalView];
+            _driver = [[iTermMetalDriver alloc] initWithMetalKitView:_metalView];
+            [_driver mtkView:_metalView drawableSizeWillChange:_metalView.drawableSize];
+            _metalView.delegate = _driver;
+        }
+
+        // Allocate a scrollview
         [_scrollview setAutoresizingMask:(NSViewWidthSizable | NSViewHeightSizable)];
+        if (@available(macOS 10.11, *)) {
+            iTermMetalClipView *metalClipView = [[[iTermMetalClipView alloc] initWithFrame:_scrollview.contentView.frame] autorelease];
+            metalClipView.metalView = _metalView;
+            _scrollview.contentView = metalClipView;
+            _scrollview.drawsBackground = NO;
+        }
+
+        _scrollview.contentView.copiesOnScroll = NO;
+
         // assign the main view
         [self addSubview:_scrollview];
-
-        // setCopiesOnScroll is off because there is a top and bottom margin in the PTYTextView and
-        // we would not want that copied.
-        [[_scrollview contentView] setCopiesOnScroll:NO];
     }
     return self;
 }
@@ -238,6 +261,9 @@ static NSDate* lastResizeDate_;
         frame.origin = NSMakePoint(horizontalPadding, verticalPadding);
         _hoverURLTextField.frame = frame;
     }
+
+    _metalView.frame = _scrollview.contentView.frame;
+    [_driver mtkView:_metalView drawableSizeWillChange:_metalView.drawableSize];
 }
 - (void)setDelegate:(id<iTermSessionViewDelegate>)delegate {
@@ -550,6 +576,10 @@ static NSDate* lastResizeDate_;
     [self updateLayout];
 }
+- (void)viewDidMoveToWindow {
+    [_delegate sessionViewDidChangeWindow];
+}
+
 #pragma mark NSDraggingSource protocol
 - (void)draggedImage:(NSImage *)draggedImage movedTo:(NSPoint)screenPoint {

sources/SolidColorView.h

@@ -12,7 +12,6 @@
 @property(nonatomic, retain) NSColor *color;
 - (instancetype)initWithFrame:(NSRect)frame color:(NSColor*)color;
-- (void)drawRect:(NSRect)dirtyRect;
 - (void)setFlipped:(BOOL)value;
 @end

sources/SolidColorView.m

@@ -29,12 +29,13 @@
             [self class], self, NSStringFromRect(self.frame), @(self.isHidden), @(self.alphaValue)];
 }
+/*
 - (void)drawRect:(NSRect)dirtyRect {
     [_color setFill];
     NSRectFill(dirtyRect);
     [super drawRect:dirtyRect];
 }
-
+*/
 - (void)setColor:(NSColor*)color {
     [_color autorelease];
     _color = [color retain];

sources/TaskNotifier.m

@@ -249,7 +249,7 @@ void UnblockTaskNotifier(void) {
         // Unblock pipe to interrupt select() whenever a PTYTask register/unregisters
         highfd = unblockPipeR;
         FD_SET(unblockPipeR, &rfds);
-        NSMutableSet* handledFds = [[NSMutableSet alloc] initWithCapacity:_tasks.count];
+        NSMutableSet* handledFds = [[NSMutableSet alloc] initWithCapacity:256];
         // Add all the PTYTask pipes
         PtyTaskDebugLog(@"run1: lock");

sources/VT100Parser.m

@@ -85,7 +85,7 @@
                                            rmlen:&rmlen
                                      incidentals:vector
                                            token:token
-                                        encoding:_encoding
+                                        encoding:self.encoding
                                       savedState:_savedStateForPartialParse
                                        dcsHooked:&_dcsHooked];
             if (token->type != VT100_WAIT) {

sources/iTermColorMap.h

@@ -7,6 +7,7 @@
 //
 #import <Cocoa/Cocoa.h>
+#include <simd/vector_types.h>
 // This would be an enum except lldb doesn't handle enums very well.
 // (lldb) po [_colorMap colorForKey:kColorMapBackground]
@@ -67,7 +68,7 @@ extern const int kColorMap24bitBase;
 // self.dimmingAmount towards a neutral gray, and is used to indicate a session's inactivity. Muting
 // moves colors towards the background color and is used by the "cursor boost" feature to make the
 // cursor stand out more.
-@interface iTermColorMap : NSObject
+@interface iTermColorMap : NSObject<NSCopying>
 @property(nonatomic, assign) BOOL dimOnlyText;
 @property(nonatomic, assign) double dimmingAmount;
@@ -91,6 +92,7 @@ extern const int kColorMap24bitBase;
 - (NSColor *)processedTextColorForTextColor:(NSColor *)textColor
                         overBackgroundColor:(NSColor*)backgroundColor;
 - (NSColor *)processedBackgroundColorForBackgroundColor:(NSColor *)color;
+- (vector_float4)fastProcessedBackgroundColorForBackgroundColor:(vector_float4)backgroundColor;
 - (NSColor *)colorByMutingColor:(NSColor *)color;
 - (NSColor *)colorByDimmingTextColor:(NSColor *)color;

sources/iTermColorMap.m → sources/iTermColorMap.mm

@@ -9,6 +9,7 @@
 #import "iTermColorMap.h"
 #import "ITAddressBookMgr.h"
 #import "NSColor+iTerm.h"
+#include <unordered_map>
 const int kColorMapForeground = 0;
 const int kColorMapBackground = 1;
@@ -53,6 +54,8 @@ const int kColorMapAnsiBrightModifier = 8;
     // This one actually uses four components.
     CGFloat _lastBackgroundComponents[4];
     NSColor *_lastBackgroundColor;
+
+    std::unordered_map<int, vector_float4> *_fastMap;
 }
 + (iTermColorMapKey)keyFor8bitRed:(int)red
@@ -65,6 +68,7 @@ const int kColorMapAnsiBrightModifier = 8;
     self = [super init];
     if (self) {
         _map = [[NSMutableDictionary alloc] init];
+        _fastMap = new std::unordered_map<int, vector_float4>();
     }
     return self;
 }
@@ -73,6 +77,7 @@ const int kColorMapAnsiBrightModifier = 8;
     [_map release];
     [_lastTextColor release];
     [_lastBackgroundColor release];
+    delete _fastMap;
     [super dealloc];
 }
@@ -92,12 +97,15 @@ const int kColorMapAnsiBrightModifier = 8;
     if (!theColor) {
         [_map removeObjectForKey:@(theKey)];
+        _fastMap->erase(theKey);
         return;
     }
     if (theColor == _map[@(theKey)])
         return;
+    CGFloat components[4];
+    [theColor getComponents:components];
     if (theKey == kColorMapBackground) {
         _backgroundRed = [theColor redComponent];
         _backgroundGreen = [theColor greenComponent];
@@ -111,6 +119,12 @@ const int kColorMapAnsiBrightModifier = 8;
     }
     _map[@(theKey)] = theColor;
+    (*_fastMap)[theKey] = (vector_float4){
+        (float)components[0],
+        (float)components[1],
+        (float)components[2],
+        (float)components[3]
+   };
     [_delegate colorMap:self didChangeColorForKey:theKey];
 }
@@ -147,6 +161,16 @@ const int kColorMapAnsiBrightModifier = 8;
     result[3] = rgb1[3];
 }
+- (vector_float4)fastAverageComponents:(vector_float4)rgb1 with:(vector_float4)rgb2 alpha:(float)alpha {
+    vector_float4 result = {
+        rgb1.x * (1 - alpha) + rgb2.x * alpha,
+        rgb1.y * (1 - alpha) + rgb2.y * alpha,
+        rgb1.z * (1 - alpha) + rgb2.z * alpha,
+        rgb1.w
+    };
+    return result;
+}
+
 // There is an issue where where the passed-in color can be in a different color space than the
 // default background color. It doesn't make sense to combine RGB values from different color
 // spaces. The effects are generally subtle.
@@ -265,6 +289,40 @@ const int kColorMapAnsiBrightModifier = 8;
                                   count:4];
 }
+- (vector_float4)fastProcessedBackgroundColorForBackgroundColor:(vector_float4)backgroundColor {
+    vector_float4 defaultBackgroundComponents = (*_fastMap)[kColorMapBackground];
+    const vector_float4 mutedRgb = [self fastAverageComponents:backgroundColor with:defaultBackgroundComponents alpha:_mutingAmount];
+    vector_float4 grayRgb { 0.5, 0.5, 0.5, 1 };
+
+    BOOL shouldDim = !_dimOnlyText && _dimmingAmount > 0;
+    // If dimOnlyText is set then text and non-default background colors get dimmed toward black.
+    if (_dimOnlyText) {
+        const BOOL isDefaultBackgroundColor =
+        (fabs(backgroundColor.x - defaultBackgroundComponents.x) < 0.01 &&
+         fabs(backgroundColor.y - defaultBackgroundComponents.y) < 0.01 &&
+         fabs(backgroundColor.z - defaultBackgroundComponents.z) < 0.01);
+        if (!isDefaultBackgroundColor) {
+            grayRgb = (vector_float4){
+                (float)_backgroundBrightness,
+                (float)_backgroundBrightness,
+                (float)_backgroundBrightness,
+                1
+            };
+            shouldDim = YES;
+        }
+    }
+
+    vector_float4 dimmedRgb;
+    if (shouldDim) {
+        dimmedRgb = [self fastAverageComponents:mutedRgb with:grayRgb alpha:_dimmingAmount];
+    } else {
+        dimmedRgb = mutedRgb;
+    }
+    dimmedRgb.w = backgroundColor.w;
+
+    return dimmedRgb;
+}
+
 // There is an issue where where the passed-in color can be in a different color space than the
 // default background color. It doesn't make sense to combine RGB values from different color
 // spaces. The effects are generally subtle.
@@ -383,4 +441,36 @@ const int kColorMapAnsiBrightModifier = 8;
     return nil;
 }
+- (id)copyWithZone:(NSZone *)zone {
+    iTermColorMap *other = [[iTermColorMap alloc] init];
+    if (!other) {
+        return nil;
+    }
+
+    other->_backgroundBrightness = _backgroundBrightness;
+    other->_backgroundRed = _backgroundRed;
+    other->_backgroundGreen = _backgroundGreen;
+    other->_backgroundBlue = _backgroundBlue;
+
+    memmove(other->_lastTextComponents, _lastTextComponents, sizeof(_lastTextComponents));
+    other->_lastTextColor = [_lastTextColor retain];
+
+    memmove(other->_lastBackgroundComponents, _lastBackgroundComponents, sizeof(_lastBackgroundComponents));
+    other->_lastBackgroundColor = [_lastBackgroundColor retain];
+
+    other->_dimOnlyText = _dimOnlyText;
+    other->_dimmingAmount = _dimmingAmount;
+
+    other->_mutingAmount = _mutingAmount;
+
+    other->_minimumContrast = _minimumContrast;
+
+    other->_delegate = _delegate;
+
+    other->_map = [_map mutableCopy];
+    other->_fastMap = new std::unordered_map<int, vector_float4>(*_fastMap);
+
+    return other;
+}
+
 @end

sources/iTermMetalFrameData.h

+//
+//  iTermMetalFrameData.h
+//  iTerm2SharedARC
+//
+//  Created by George Nachman on 10/27/17.
+//
+
+#import <Foundation/Foundation.h>
+
+#import "iTermPreciseTimer.h"
+#import "VT100GridTypes.h"
+
+typedef struct {
+    iTermPreciseTimerStats mainThreadStats;
+    iTermPreciseTimerStats getCurrentDrawableStats;
+    iTermPreciseTimerStats getCurrentRenderPassDescriptorStats;
+    iTermPreciseTimerStats dispatchStats;
+    iTermPreciseTimerStats prepareStats;
+    iTermPreciseTimerStats waitForGroup;
+    iTermPreciseTimerStats finalizeStats;
+    iTermPreciseTimerStats metalSetupStats;
+    iTermPreciseTimerStats renderingStats;
+    iTermPreciseTimerStats endToEnd;
+} iTermMetalFrameDataStatsBundle;
+
+extern void iTermMetalFrameDataStatsBundleInitialize(iTermMetalFrameDataStatsBundle *bundle);
+extern void iTermMetalFrameDataStatsBundleAdd(iTermMetalFrameDataStatsBundle *dest, iTermMetalFrameDataStatsBundle *source);
+
+@protocol iTermMetalDriverDataSourcePerFrameState;
+@class iTermMetalRendererTransientState;
+@class iTermMetalRowData;
+@class MTKView;
+@class MTLRenderPassDescriptor;
+@protocol CAMetalDrawable;
+
+@interface iTermMetalFrameData : NSObject
+@property (nonatomic, strong) id<iTermMetalDriverDataSourcePerFrameState> perFrameState;
+@property (nonatomic, strong) NSMutableDictionary<NSString *, __kindof iTermMetalRendererTransientState *> *transientStates;
+@property (nonatomic, strong) NSMutableArray<iTermMetalRowData *> *rows;
+@property (nonatomic) VT100GridSize gridSize;
+@property (nonatomic) CGFloat scale;
+@property (atomic, strong) NSString *status;
+@property (nonatomic, strong) MTLRenderPassDescriptor *renderPassDescriptor;
+@property (nonatomic, strong) id<CAMetalDrawable> drawable;
+
+- (void)loadFromView:(MTKView *)view;
+- (void)prepareWithBlock:(void (^)(void))block;
+- (void)waitForUpdatesToFinishOnGroup:(dispatch_group_t)group
+                              onQueue:(dispatch_queue_t)queue
+                             finalize:(void (^)(void))finalize
+                               render:(void (^)(void))render;
+- (void)didComplete;
+- (void)addStatsTo:(iTermMetalFrameDataStatsBundle *)dest;
+
+@end
+