Add an experimental feature to draw an outline around underline and vertical...

Add an experimental feature to draw an outline around underline and vertical bar cursors to improve distinction from text. Suggested in issue 4614.

sources/iTermAdvancedSettingsModel.h

@@ -179,5 +179,6 @@
 + (BOOL)excludeBackgroundColorsFromCopiedStyle;
 + (BOOL)useGCDUpdateTimer;
 + (BOOL)fullHeightCursor;
++ (BOOL)drawOutlineAroundCursor;
 @end

sources/iTermAdvancedSettingsModel.m

@@ -265,5 +265,6 @@ DEFINE_BOOL(trackingRunloopForLiveResize, YES, @"Experimental Features: Use a tr
 DEFINE_BOOL(enableAPIServer, NO, @"Experimental Features: Enable websocket API server.\nYou must restart iTerm2 for this change to take effect.");
 DEFINE_BOOL(useGCDUpdateTimer, NO, @"Experimental Features: Use GCD-based update timer instead of NSTimer.\nThis should cause more regular screen updates. Restart iTerm2 after changing this setting.");
+DEFINE_BOOL(drawOutlineAroundCursor, NO, @"Experimental Features: Draw outline around underline and vertical bar cursors using background color.");
 @end

sources/iTermCursor.h

@@ -48,7 +48,7 @@ typedef struct {
                smart:(BOOL)smart
              focused:(BOOL)focused
                coord:(VT100GridCoord)coord
-          cellHeight:(CGFloat)cellHeight;
+             outline:(BOOL)outline;
 @end

sources/iTermCursor.m

@@ -47,7 +47,18 @@
                smart:(BOOL)smart
              focused:(BOOL)focused
                coord:(VT100GridCoord)coord
-          cellHeight:(CGFloat)cellHeight {
+             outline:(BOOL)outline {
+}
+
+- (void)drawOutlineOfRect:(NSRect)cursorRect withColor:(NSColor *)color {
+    [[color colorWithAlphaComponent:0.75] set];
+    NSRect rect = cursorRect;
+    CGFloat frameWidth = 0.5;
+    rect.origin.x -= frameWidth;
+    rect.origin.y -= frameWidth;
+    rect.size.width += frameWidth * 2;
+    rect.size.height += frameWidth * 2;
+    NSFrameRectWithWidthUsingOperation(rect, 0.5, NSCompositeSourceOver);
 }
 @end
@@ -62,12 +73,18 @@
                smart:(BOOL)smart
              focused:(BOOL)focused
                coord:(VT100GridCoord)coord
-          cellHeight:(CGFloat)cellHeight {
-    [backgroundColor set];
-    NSRectFill(NSMakeRect(rect.origin.x,
-                          rect.origin.y + rect.size.height - 2,
-                          ceil(rect.size.width),
-                          2));
+             outline:(BOOL)outline {
+    const CGFloat height = 2;
+    NSRect cursorRect = NSMakeRect(rect.origin.x,
+                                   rect.origin.y + rect.size.height - height,
+                                   ceil(rect.size.width),
+                                   height);
+    if (outline) {
+        [self drawOutlineOfRect:cursorRect withColor:backgroundColor];
+    } else {
+        [backgroundColor set];
+        NSRectFill(cursorRect);
+    }
 }
 @end
@@ -82,9 +99,14 @@
                smart:(BOOL)smart
              focused:(BOOL)focused
                coord:(VT100GridCoord)coord
-          cellHeight:(CGFloat)cellHeight {
-    [backgroundColor set];
-    NSRectFill(NSMakeRect(rect.origin.x, rect.origin.y, 1, rect.size.height));
+             outline:(BOOL)outline {
+    NSRect cursorRect = NSMakeRect(rect.origin.x, rect.origin.y, 1, rect.size.height);
+    if (outline) {
+        [self drawOutlineOfRect:cursorRect withColor:backgroundColor];
+    } else {
+        [backgroundColor set];
+        NSRectFill(cursorRect);
+    }
 }
 @end
@@ -99,7 +121,9 @@
                smart:(BOOL)smart
              focused:(BOOL)focused
                coord:(VT100GridCoord)coord
-          cellHeight:(CGFloat)cellHeight {
+             outline:(BOOL)outline {
+    assert(!outline);
+
     // Draw the colored box/frame
     if (smart) {
         iTermCursorNeighbors neighbors = [self.delegate cursorNeighbors];

sources/iTermTextDrawingHelper.m

@@ -371,7 +371,7 @@ typedef struct iTermTextColorContext {
     const BOOL drawCursorBeforeText = (_cursorType == CURSOR_UNDERLINE || _cursorType == CURSOR_VERTICAL);
     if (drawCursorBeforeText) {
-        [self drawCursor];
+        [self drawCursor:NO];
     }
     // Now iterate over the lines and paint the characters.
@@ -410,8 +410,12 @@ typedef struct iTermTextColorContext {
                          cursorHeight:_cellSizeWithoutSpacing.height
                                   ctx:ctx];
     _blinkingFound |= self.cursorBlinking;
-    if (!drawCursorBeforeText) {
-        [self drawCursor];
+    if (drawCursorBeforeText) {
+        if ([iTermAdvancedSettingsModel drawOutlineAroundCursor]) {
+            [self drawCursor:YES];
+        }
+    } else {
+        [self drawCursor:NO];
     }
 }
@@ -2224,8 +2228,21 @@ static BOOL iTermTextDrawingHelperIsCharacterDrawable(screen_char_t *c,
     }
 }
-- (void)drawCursor {
-    DLog(@"drawCursor");
+- (NSRect)cursorFrameIncludingDoubleWidthAdjustment {
+    screen_char_t *theLine = [self.delegate drawingHelperLineAtScreenIndex:_cursorCoord.y];
+    BOOL isDoubleWidth;
+    [self charForCursorAtColumn:_cursorCoord.x
+                         inLine:theLine
+                    doubleWidth:&isDoubleWidth];
+    NSRect rect = [self cursorFrame];
+    if (isDoubleWidth) {
+        rect.size.width *= 2;
+    }
+    return rect;
+}
+
+- (void)drawCursor:(BOOL)outline {
+    DLog(@"drawCursor:%@", @(outline));
     // Update the last time the cursor moved.
     NSTimeInterval now = [NSDate timeIntervalSinceReferenceDate];
@@ -2246,7 +2263,11 @@ static BOOL iTermTextDrawingHelperIsCharacterDrawable(screen_char_t *c,
         // Get the color of the cursor.
         NSColor *cursorColor;
-        cursorColor = [self backgroundColorForCursor];
+        if (outline) {
+            cursorColor = [_colorMap colorForKey:kColorMapBackground];
+        } else {
+            cursorColor = [self backgroundColorForCursor];
+        }
         NSRect rect = [self cursorFrame];
         if (isDoubleWidth) {
             rect.size.width *= 2;
@@ -2274,7 +2295,7 @@ static BOOL iTermTextDrawingHelperIsCharacterDrawable(screen_char_t *c,
                        smart:_useSmartCursorColor
                      focused:((_isInKeyWindow && _textViewIsActiveSession) || _shouldDrawFilledInCursor)
                        coord:_cursorCoord
-                  cellHeight:_cellSize.height];
+                     outline:outline];
         if (_showSearchingCursor) {
             NSImage *image = [NSImage imageNamed:@"SearchCursor"];
             if (image) {