Question

我开始开发一个编辑应用程序，我可以从图库到应用程序拍摄图像但是我不知道如何捏缩放和平移请任何人告诉我怎么做

Answer 1

在这里写下所有内容将太广泛了。基本上，有很多库可以为ImageView提供缩放手势。

您可以查看他们的代码或也使用该库。这是在github上评价最高的两个。

您只需要使用他们的ImageView，ImageView就会显示手势。像

<com.github.chrisbanes.photoview.PhotoView
    android:id="@+id/photo_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

Answer 2

这只是我项目的一小部分。

class ZoomView @JvmOverloads constructor(
        context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : ImageView(context, attrs, defStyleAttr) {

    private val imageBound = RectF()
    private val imageMatrixArray = FloatArray(9)
    private val scaleDetector: ScaleGestureDetector

    private var scale: Float = 1f
    private var scalePoint = PointF()
    private var translateX: Float = 0f
    private var translateY: Float = 0f
    private var lastTouchX = 0f
    private var lastTouchY = 0f
    private var lastDownTouchX = 0f
    private var lastDownTouchY = 0f
    private var lastGestureX = 0f
    private var lastGestureY = 0f
    private var isScaling = false
    private var activePointerId = -1
    private var drawableHeight = -1.0
    private var drawableWidth = -1.0
    private var minBoxRectSide = 0

    init {

        scaleDetector = ScaleGestureDetector(context, object : ScaleGestureDetector
        .SimpleOnScaleGestureListener() {
            override fun onScaleBegin(detector: ScaleGestureDetector?): Boolean {
                isScaling = true
                return super.onScaleBegin(detector)
            }

            override fun onScale(detector: ScaleGestureDetector): Boolean {
                scale *= detector.scaleFactor
                scale = Math.min(scale, 25f)
                scale = Math.max(0.5f, scale)

                invalidate()
                return true
            }

            override fun onScaleEnd(detector: ScaleGestureDetector?) {
                super.onScaleEnd(detector)
                isScaling = false
            }
        })
    }

    override fun onLayout(changed: Boolean, left: Int, top: Int, right: Int, bottom: Int) {
        super.onLayout(changed, left, top, right, bottom)
        //Timber.d("Image on layout : layoutChanged = $changed")
        if (changed) {
            drawable?.let {
                resetBoxRect(it, left, right, top, bottom)
            }
        }
    }

    private fun resetBoxRect(it: Drawable, left: Int, right: Int, top: Int, bottom: Int) {
        //Timber.d("image coordinates $left, $top, $right, $bottom")

        drawableHeight = it.intrinsicHeight.toDouble()
        drawableWidth = it.intrinsicWidth.toDouble()

        imageMatrix.getValues(imageMatrixArray)
        imageBound.set((left + right) / 2 - imageMatrixArray[Matrix.MSCALE_X] * it.intrinsicWidth / 2,
                (bottom - top) / 2 - imageMatrixArray[Matrix.MSCALE_Y] * it.intrinsicHeight / 2,
                (left + right) / 2 + imageMatrixArray[Matrix.MSCALE_X] * it.intrinsicWidth / 2,
                (bottom - top) / 2 + imageMatrixArray[Matrix.MSCALE_Y] * it.intrinsicHeight / 2)

        //Timber.d("Image bound $imageBound, and $boxRect")
        minBoxRectSide = (.01f * Math.max(imageBound.bottom - imageBound.top, imageBound.right - imageBound.left)).toInt()
        scale = 1f
        translateX = 0f
        translateY = 0f

    }

    override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
        super.onSizeChanged(w, h, oldw, oldh)
        scalePoint.set(w / 2.toFloat(), h / 2.toFloat())
    }

    override fun setImageDrawable(drawable: Drawable?) {
        super.setImageDrawable(drawable)
        drawable?.let {
            if (imageMatrixArray != null) {
                resetBoxRect(it, left, right, top, bottom)
            }
        }
    }

    override fun onTouchEvent(event: MotionEvent): Boolean {
        parent.requestDisallowInterceptTouchEvent(true)
        //Timber.d("On touch start")
        scaleDetector.onTouchEvent(event)
        //Timber.d("On touch gesture sent")
        when (event.actionMasked) {
            MotionEvent.ACTION_DOWN -> onActionDown(event)
            MotionEvent.ACTION_MOVE -> onMoveEvent(event)
            MotionEvent.ACTION_CANCEL -> activePointerId = -1
            MotionEvent.ACTION_UP -> {
                activePointerId = -1
            }
            MotionEvent.ACTION_POINTER_UP -> onActionUp(event)
        }
        return true
    }


    private fun onActionDown(event: MotionEvent) {
        val actionIndex = event.actionIndex
        lastDownTouchX = event.getX(actionIndex)
        lastDownTouchY = event.getY(actionIndex)

        lastTouchX = event.getX(actionIndex)
        lastTouchY = event.getY(actionIndex)
        lastGestureX = lastTouchX
        lastGestureY = lastTouchY
        activePointerId = event.getPointerId(0)

        invalidate()
    }

    private fun onMoveEvent(event: MotionEvent) {
        if (!isScaling) {
            val index = event.findPointerIndex(activePointerId)
            val dx = (event.getX(index) - lastTouchX) / scale
            val dy = (event.getY(index) - lastTouchY) / scale
            lastTouchX = event.getX(index)
            lastTouchY = event.getY(index)

            if (Math.abs(translateX + dx) < imageBound.right - imageBound.left)
                translateX += dx
            if (Math.abs(translateY + dy) < imageBound.bottom - imageBound.top)
                translateY += dy

            invalidate()

        }
    }

    private fun onActionUp(event: MotionEvent) {
        val pointerIndex = event.actionIndex
        val pointerId = event.getPointerId(pointerIndex)
        if (pointerId == activePointerId) {
            // This was our active pointer going up. Choose a new
            // active pointer and adjust accordingly.
            val newPointerIndex = if (pointerIndex == 0) 1 else 0
            lastTouchX = event.getX(newPointerIndex)
            lastTouchY = event.getY(newPointerIndex)
            activePointerId = event.getPointerId(newPointerIndex)
        }
    }

    override fun onDraw(canvas: Canvas) {
        canvas.save()

        canvas.scale(scale, scale, scalePoint.x, scalePoint.y)
        canvas.translate(translateX, translateY)

        super.onDraw(canvas)

        canvas.restore()
    }
}

可以通过这种方式将视图用于xml：-

<com.myproject.app.widgets.ZoomView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:src="@drawable/abc" />

如何捏缩放从图库中选取的图像

2 个答案: