feat: mock the input for proper first renders measurements

Author: szydlovsky

ios/internals/EnrichedTextInputViewShadowNode.h

@@ -35,6 +35,8 @@ class EnrichedTextInputViewShadowNode : public ConcreteViewShadowNode<
 
     private:
     int localForceHeightRecalculationCounter_;
+    static id mockTextInputView_;
+    void setupMockTextInputView_();
 };
 
 } // namespace facebook::react

ios/internals/EnrichedTextInputViewShadowNode.mm

@@ -8,13 +8,33 @@
 namespace facebook::react {
 
 extern const char EnrichedTextInputViewComponentName[] = "EnrichedTextInputView";
+id EnrichedTextInputViewShadowNode::mockTextInputView_ = nullptr;
 
 EnrichedTextInputViewShadowNode::EnrichedTextInputViewShadowNode(
   const ShadowNodeFragment& fragment,
   const ShadowNodeFamily::Shared& family,
   ShadowNodeTraits traits
 ): ConcreteViewShadowNode(fragment, family, traits) {
   localForceHeightRecalculationCounter_ = 0;
+  
+  // mock text input needs to be initialized on the main thread
+  if([NSThread isMainThread]) {
+    setupMockTextInputView_();
+  } else {
+    dispatch_sync(dispatch_get_main_queue(), ^{
+      setupMockTextInputView_();
+    });
+  }
+}
+
+// mock input is used for the first measure calls that need to be done when the real input isn't defined yet
+void EnrichedTextInputViewShadowNode::setupMockTextInputView_() {
+  // it's rendered far away from the viewport
+  const int veryFarAway = 20000;
+  const int mockSize = 1000;
+  mockTextInputView_ = [[EnrichedTextInputView alloc] initWithFrame:(CGRectMake(veryFarAway, veryFarAway, mockSize, mockSize))];
+  const auto props = this->getProps();
+  [mockTextInputView_ updateProps:props oldProps:nullptr];
 }
 
 EnrichedTextInputViewShadowNode::EnrichedTextInputViewShadowNode(
@@ -44,6 +64,11 @@
     EnrichedTextInputView *typedComponentObject = (EnrichedTextInputView *) componentObject;
 
     if(typedComponentObject != nullptr) {
+      // remove the mock input on the first render with a defined real input
+      if(mockTextInputView_ != nullptr) {
+        mockTextInputView_ = nullptr;
+      }
+    
       __block CGSize estimatedSize;
 
       // synchronously dispatch to main thread if needed
@@ -61,23 +86,25 @@
       };
     }
   } else {
-    // on the very first call there is no componentView that we can query for the component height
-    // thus, a little heuristic: just put a height that is exactly height of letter "I" with default apple font and size from props
-    // in a lot of cases it will be the desired height
-    // in others, the jump on the second call will at least be smaller
-    const auto props = this->getProps();
-    const auto &typedProps = *std::static_pointer_cast<EnrichedTextInputViewProps const>(props);
-    NSAttributedString *attrStr = [[NSAttributedString alloc] initWithString:@"I" attributes:@{NSFontAttributeName: [UIFont systemFontOfSize:typedProps.fontSize]}];
-    CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)attrStr);
-    const CGSize &suggestedSize = CTFramesetterSuggestFrameSizeWithConstraints(
-      framesetter,
-      CFRangeMake(0, 1),
-      nullptr,
-      CGSizeMake(layoutConstraints.maximumSize.width, DBL_MAX),
-      nullptr
-    );
-    
-    return {suggestedSize.width, suggestedSize.height};
+    if(mockTextInputView_ == nullptr) {
+      return Size();
+    }
+  
+    __block CGSize estimatedSize;
+      
+    // synchronously dispatch to main thread if needed
+    if([NSThread isMainThread]) {
+      estimatedSize = [mockTextInputView_ measureSize:layoutConstraints.maximumSize.width];
+    } else {
+      dispatch_sync(dispatch_get_main_queue(), ^{
+        estimatedSize = [mockTextInputView_ measureSize:layoutConstraints.maximumSize.width];
+      });
+    }
+
+    return {
+      estimatedSize.width,
+      MIN(estimatedSize.height, layoutConstraints.maximumSize.height)
+    };
   }
 
   return Size();