First double tap unregistered

[bakjoul]

Hello,

I don't know if i'm doing anything wrong but on the first double tap, the view is not responsive, it does not zoom.
More precisely, on an emulator, it just reloads the image, then the double taps will work. On a physical device, the first double tap does nothing, then from the second one it works.
The first pinch device does work though on a physical device. (The view disappears on the emulator but it doesn't matter.)

[jsibbold]

Are you using it in a ViewPager or anything like that?

[bakjoul]

Exactly, i,'m using it in a ViewPager2.

[OsamaGhafoor]

Yes, it's happeing but issue is in the OnTouch of very first call... and solution is:

---

---

// 🛠️ Fix: Prevent zoom on first image tap by lazy initializing MATRIX mode
private var matrixModeInitialized = false

override fun onTouchEvent(event: MotionEvent): Boolean {
    gestureDetector?.onTouchEvent(event)

    if (!isClickable && isEnabled && (isZoomable || isTranslatable)) {
        currentPointerCount = event.pointerCount

        if (startValues == null) {
            setStartValues()
        }

        // 👇 Lazy initialize MATRIX mode on user interaction (first MOVE or 2 fingers)
        if (!matrixModeInitialized &&
            (event.actionMasked == MotionEvent.ACTION_MOVE || event.pointerCount > 1)
        ) {
            if (scaleType != ScaleType.MATRIX) {
                super.setScaleType(ScaleType.MATRIX)
                matrixModeInitialized = true
                Log.d("TouchEvent", "ScaleType set to MATRIX after user interaction")
            }
        }

        if (doubleTapToZoom && doubleTapDetected) {
            doubleTapDetected = false
            singleTapDetected = false

            matrix.set(imageMatrix)
            matrix.getValues(matrixValues)

            if (matrixValues[Matrix.MSCALE_X] != startValues!![Matrix.MSCALE_X]) {
                reset()
            } else {
                val zoomMatrix = Matrix(matrix)
                zoomMatrix.postScale(
                    doubleTapToZoomScaleFactor,
                    doubleTapToZoomScaleFactor,
                    scaleDetector!!.focusX,
                    scaleDetector!!.focusY
                )
                animateScaleAndTranslationToMatrix(zoomMatrix, RESET_DURATION)
            }
            return true
        }

        if (matrixModeInitialized) {
            matrix.set(imageMatrix)
            matrix.getValues(matrixValues)
            updateBounds(matrixValues)
            scaleDetector?.onTouchEvent(event)

            if (!singleTapDetected) {
                if (event.actionMasked == MotionEvent.ACTION_DOWN ||
                    currentPointerCount != previousPointerCount
                ) {
                    last[scaleDetector!!.focusX] = scaleDetector!!.focusY
                } else if (event.actionMasked == MotionEvent.ACTION_MOVE) {
                    val focusx = scaleDetector!!.focusX
                    val focusy = scaleDetector!!.focusY

                    if (allowTranslate(event)) {
                        val xdistance = getXDistance(focusx, last.x)
                        val ydistance = getYDistance(focusy, last.y)
                        matrix.postTranslate(xdistance, ydistance)
                    }

                    if (allowZoom(event)) {
                        matrix.postScale(scaleBy, scaleBy, focusx, focusy)
                        currentScaleFactor =
                            matrixValues[Matrix.MSCALE_X] / startValues!![Matrix.MSCALE_X]
                    }

                    imageMatrix = matrix
                    last[focusx] = focusy
                }

                if (event.actionMasked == MotionEvent.ACTION_UP ||
                    event.actionMasked == MotionEvent.ACTION_CANCEL
                ) {
                    scaleBy = 1f
                    resetImage()
                }
            }

            parent.requestDisallowInterceptTouchEvent(disallowParentTouch(event))
            previousPointerCount = currentPointerCount
            return true
        }
    }

    return super.onTouchEvent(event)
}