[react-native] Open-source ReactART for native

Libraries/ART/ARTText.m

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+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import "ARTText.h"
+
+#import <CoreText/CoreText.h>
+
+@implementation ARTText
+
+- (void)setAlignment:(CTTextAlignment)alignment
+{
+  [self invalidate];
+  _alignment = alignment;
+}
+
+- (void)setTextFrame:(ARTTextFrame)frame
+{
+  if (frame.lines != _textFrame.lines && _textFrame.count) {
+    // We must release each line before overriding the old one
+    for (int i = 0; i < _textFrame.count; i++) {
+      CFRelease(_textFrame.lines[0]);
+    }
+    free(_textFrame.lines);
+    free(_textFrame.widths);
+  }
+  [self invalidate];
+  _textFrame = frame;
+}
+
+- (void)dealloc
+{
+  if (_textFrame.count) {
+    // We must release each line before freeing up this struct
+    for (int i = 0; i < _textFrame.count; i++) {
+      CFRelease(_textFrame.lines[0]);
+    }
+    free(_textFrame.lines);
+    free(_textFrame.widths);
+  }
+}
+
+- (void)renderLayerTo:(CGContextRef)context
+{
+  ARTTextFrame frame = self.textFrame;
+
+  if ((!self.fill && !self.stroke) || !frame.count) {
+    return;
+  }
+
+  // to-do: draw along a path
+
+  CGTextDrawingMode mode = kCGTextStroke;
+  if (self.fill) {
+    if ([self.fill applyFillColor:context]) {
+      mode = kCGTextFill;
+    } else {
+
+      for (int i = 0; i < frame.count; i++) {
+        CGContextSaveGState(context);
+        // Inverse the coordinate space since CoreText assumes a bottom-up coordinate space
+        CGContextScaleCTM(context, 1.0, -1.0);
+        CGContextSetTextDrawingMode(context, kCGTextClip);
+        [self renderLineTo:context atIndex:i];
+        // Inverse the coordinate space back to the original before filling
+        CGContextScaleCTM(context, 1.0, -1.0);
+        [self.fill paint:context];
+        // Restore the state so that the next line can be clipped separately
+        CGContextRestoreGState(context);
+      }
+
+      if (!self.stroke) {
+        return;
+      }
+    }
+  }
+  if (self.stroke) {
+    CGContextSetStrokeColorWithColor(context, self.stroke);
+    CGContextSetLineWidth(context, self.strokeWidth);
+    CGContextSetLineCap(context, self.strokeCap);
+    CGContextSetLineJoin(context, self.strokeJoin);
+    ARTCGFloatArray dash = self.strokeDash;
+    if (dash.count) {
+      CGContextSetLineDash(context, 0, dash.array, dash.count);
+    }
+    if (mode == kCGTextFill) {
+      mode = kCGTextFillStroke;
+    }
+  }
+
+  CGContextSetTextDrawingMode(context, mode);
+
+  // Inverse the coordinate space since CoreText assumes a bottom-up coordinate space
+  CGContextScaleCTM(context, 1.0, -1.0);
+  for (int i = 0; i < frame.count; i++) {
+    [self renderLineTo:context atIndex:i];
+  }
+}
+
+- (void)renderLineTo:(CGContextRef)context atIndex:(int)index
+{
+  ARTTextFrame frame = self.textFrame;
+  CGFloat shift;
+  switch (self.alignment) {
+    case kCTTextAlignmentRight:
+      shift = frame.widths[index];
+      break;
+    case kCTTextAlignmentCenter:
+      shift = (frame.widths[index] / 2);
+      break;
+    default:
+      shift = 0;
+      break;
+  }
+  // We should consider snapping this shift to device pixels to improve rendering quality
+  // when a line has subpixel width.
+  CGContextSetTextPosition(context, -shift, -frame.baseLine - frame.lineHeight * index);
+  CTLineRef line = frame.lines[index];
+  CTLineDraw(line, context);
+}
+
+@end