_limitAndApplyTransformation()

in react/features/base/media/components/native/VideoTransform.js [374:461]
67 lines of code
3 McCabe index (conditional complexity)

    _limitAndApplyTransformation(transform: Transform) {
        const { layout } = this.state;

        if (layout) {
            const { scale } = this.state.transform;
            const { scale: newScaleUnlimited } = transform;
            let {
                translateX: newTranslateX,
                translateY: newTranslateY
            } = transform;

            // Scale is only limited to MIN_SCALE here to detect downscale
            // gesture later.
            const newScale = Math.max(newScaleUnlimited, MIN_SCALE);

            // The A and D points of the original View (before transform).
            const originalLayout = {
                a: {
                    x: layout.x,
                    y: layout.y
                },
                d: {
                    x: layout.x + layout.width,
                    y: layout.y + layout.height
                }
            };

            // The center point (midpoint) of the transformed View.
            const transformedCenterPoint = {
                x: ((layout.x + layout.width) / 2) + (newTranslateX * newScale),
                y: ((layout.y + layout.height) / 2) + (newTranslateY * newScale)
            };

            // The size of the transformed View.
            const transformedSize = {
                height: layout.height * newScale,
                width: layout.width * newScale
            };

            // The A and D points of the transformed View.
            const transformedLayout = {
                a: {
                    x: transformedCenterPoint.x - (transformedSize.width / 2),
                    y: transformedCenterPoint.y - (transformedSize.height / 2)
                },
                d: {
                    x: transformedCenterPoint.x + (transformedSize.width / 2),
                    y: transformedCenterPoint.y + (transformedSize.height / 2)
                }
            };

            let _MAX_OFFSET = MAX_OFFSET;

            if (newScaleUnlimited < scale) {
                // This is a negative scale event so we dynamycally reduce the
                // MAX_OFFSET to get the screen back to the center on
                // downscaling.
                _MAX_OFFSET = Math.min(MAX_OFFSET, MAX_OFFSET * (newScale - 1));
            }

            // Correct move matrix if it goes out of the view
            // too much (_MAX_OFFSET).
            newTranslateX
                -= Math.max(
                    transformedLayout.a.x - originalLayout.a.x - _MAX_OFFSET,
                    0);
            newTranslateX
                += Math.max(
                    originalLayout.d.x - transformedLayout.d.x - _MAX_OFFSET,
                    0);
            newTranslateY
                -= Math.max(
                    transformedLayout.a.y - originalLayout.a.y - _MAX_OFFSET,
                    0);
            newTranslateY
                += Math.max(
                    originalLayout.d.y - transformedLayout.d.y - _MAX_OFFSET,
                    0);

            this.setState({
                transform: {
                    scale: newScale,
                    translateX: Math.round(newTranslateX),
                    translateY: Math.round(newTranslateY)
                }
            });
        }
    }