The Drawing From the Example Code is Based on Landscape Right

[cod3kid]

The Problem

The Skia drawing was appearing in landscape orientation even when holding the phone in portrait mode. The bounding boxes from object detection were drawn in the wrong position/orientation.

Root Cause

The issue was a coordinate space mismatch between:

MediaPipe's bounding boxes: Returned in the raw camera buffer coordinates (landscape 1920×1080)
Reported image dimensions: MPImage.width/height was returning the orientation-adjusted dimensions (portrait 1080×1920)
No rotation transformation: The bounding box coordinates were never rotated to match the displayed portrait orientation

[cod3kid]

The Fix

I made changes in two files in objectdetection

1. ObjectDetectorHelper.swift

• Changed to report raw buffer dimensions from CVPixelBuffer
• Stored the orientation for later use in coordinate transformation

2. ConvertHelpers.swift

• Added a rotateBoundingBox() function that transforms bounding box coordinates based on orientation
• For portrait mode (90° rotation): new_x = old_y, new_y = rawWidth - old_x
• Updated convertResultBundleToDictionary() to apply the rotation transformation before sending results to JavaScript
• After rotation, swapped the reported dimensions to match the rotated coordinate space

Summary
The fix ensures that bounding boxes are rotated from raw buffer space to display space in the native iOS layer, and the reported dimensions match the rotated coordinate system. This way, the JavaScript frameRectToView() function receives coordinates that align with the actual camera preview orientation.