ae9eab3533
* Android tap-to-focus and improved (continuous) auto-focus Tap-to-focus - On tap, compute focus area around motion event's location, and pass this to the camera parameters as the new focus area. - Adds RCTCameraUtils.java file, so far with only a single function that helps compute the focus area from a motion event. This file can serve as a location for utility constants and functions for the rest of the app, where such things can be extracted out. Improved (continuous) auto-focus - Use FOCUS_MODE_CONTINUOUS_PICTURE/VIDEO when possible to enable continuous auto-focus; fall back to FOCUS_MODE_AUTO otherwise, if able. Other changes - Update README to specify differences between iOS and Android for focus and zoom functionality. - Update AndroidManifest with more thorough list of permissions and features. - Update Example package.json react and react-native dependencies to match root package's package.json. * Example: default empty onFocusChanged callback - Enables default tap-to-focus behavior in Example app, facilitating testing of focus features in the Example app
73 lines
3.5 KiB
Java
73 lines
3.5 KiB
Java
package com.lwansbrough.RCTCamera;
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import android.graphics.Rect;
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import android.graphics.RectF;
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import android.hardware.Camera;
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import android.view.MotionEvent;
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public class RCTCameraUtils {
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private static final int FOCUS_AREA_MOTION_EVENT_EDGE_LENGTH = 100;
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private static final int FOCUS_AREA_WEIGHT = 1000;
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/**
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* Computes a Camera.Area corresponding to the new focus area to focus the camera on. This is
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* done by deriving a square around the center of a MotionEvent pointer (with side length equal
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* to FOCUS_AREA_MOTION_EVENT_EDGE_LENGTH), then transforming this rectangle's/square's
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* coordinates into the (-1000, 1000) coordinate system used for camera focus areas.
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*
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* Also note that we operate on RectF instances for the most part, to avoid any integer
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* division rounding errors going forward. We only round at the very end for playing into
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* the final focus areas list.
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*
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* @throws RuntimeException if unable to compute valid intersection between MotionEvent region
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* and SurfaceTexture region.
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*/
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protected static Camera.Area computeFocusAreaFromMotionEvent(final MotionEvent event, final int surfaceTextureWidth, final int surfaceTextureHeight) {
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// Get position of first touch pointer.
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final int pointerId = event.getPointerId(0);
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final int pointerIndex = event.findPointerIndex(pointerId);
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final float centerX = event.getX(pointerIndex);
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final float centerY = event.getY(pointerIndex);
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// Build event rect. Note that coordinates increase right and down, such that left <= right
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// and top <= bottom.
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final RectF eventRect = new RectF(
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centerX - FOCUS_AREA_MOTION_EVENT_EDGE_LENGTH, // left
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centerY - FOCUS_AREA_MOTION_EVENT_EDGE_LENGTH, // top
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centerX + FOCUS_AREA_MOTION_EVENT_EDGE_LENGTH, // right
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centerY + FOCUS_AREA_MOTION_EVENT_EDGE_LENGTH // bottom
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);
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// Intersect this rect with the rect corresponding to the full area of the parent surface
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// texture, making sure we are not placing any amount of the eventRect outside the parent
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// surface's area.
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final RectF surfaceTextureRect = new RectF(
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(float) 0, // left
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(float) 0, // top
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(float) surfaceTextureWidth, // right
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(float) surfaceTextureHeight // bottom
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);
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final boolean intersectSuccess = eventRect.intersect(surfaceTextureRect);
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if (!intersectSuccess) {
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throw new RuntimeException(
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"MotionEvent rect does not intersect with SurfaceTexture rect; unable to " +
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"compute focus area"
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);
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}
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// Transform into (-1000, 1000) focus area coordinate system. See
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// https://developer.android.com/reference/android/hardware/Camera.Area.html.
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// Note that if this is ever changed to a Rect instead of RectF, be cautious of integer
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// division rounding!
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final RectF focusAreaRect = new RectF(
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(eventRect.left / surfaceTextureWidth) * 2000 - 1000, // left
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(eventRect.top / surfaceTextureHeight) * 2000 - 1000, // top
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(eventRect.right / surfaceTextureWidth) * 2000 - 1000, // right
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(eventRect.bottom / surfaceTextureHeight) * 2000 - 1000 // bottom
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);
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Rect focusAreaRectRounded = new Rect();
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focusAreaRect.round(focusAreaRectRounded);
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return new Camera.Area(focusAreaRectRounded, FOCUS_AREA_WEIGHT);
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}
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}
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