Android挖取原图手指触点区域RectF(并框线标记)放大到ImageView宽高与矩阵mapRadius，Kotlin

Android挖取原图手指触点区域RectF(并框线标记)放大到ImageView宽高与矩阵mapRadius，Kotlin

这��� Android挖取原图中心区域RectF(并框线标记)放大到ImageView宽高，Kotlin-CSDN博客 实现的是把原图中心区域的一片小图挖取出来放大放到下面的ImageView里面，现在不再固定中心位置，而是以手指在上图的触点位置为中心位置，挖取一片区域图放大，然后放到下面的ImageView里面。

import android.content.Contextimport android.graphics.Bitmapimport android.graphics.BitmapFactoryimport android.graphics.Canvasimport android.graphics.Colorimport android.graphics.Matriximport android.graphics.Paintimport android.graphics.Pathimport android.graphics.RectFimport android.os.Bundleimport android.util.AttributeSetimport android.util.Logimport android.util.SizeFimport android.view.MotionEventimport android.widget.ImageViewimport androidx.appcompat.app.AppCompatActivityimport androidx.appcompat.widget.AppCompatImageViewimport androidx.core.content.ContextCompatimport androidx.core.graphics.toRectclass MainActivity : AppCompatActivity() {    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        setContentView(R.layout.activity_main)        val miv = findViewById(R.id.iv)        val iv = findViewById(R.id.result)        miv.setResultImage(iv)    }}class MyImageView : AppCompatImageView {    private var W = 0    private var H = 0    private val mSizeF = SizeF(400f, 200f)    private var mOriginBmp: Bitmap? = null    private var mPaint = Paint()    private var result: ImageView? = null    private var mTouchX = 0f    private var mTouchY = 0f    private var mCanDraw = false    private var mCircleRadius = 30f    constructor(ctx: Context, attrs: AttributeSet) : super(ctx, attrs) {        mPaint.style = Paint.Style.STROKE        mPaint.strokeWidth = 5f        mPaint.isAntiAlias = true        mPaint.color = Color.RED        mOriginBmp = getOriginalBitmap(ctx, R.mipmap.image)        Log.d("fly", "origin bmp w=${mOriginBmp!!.width} h=${mOriginBmp!!.height}")    }    private fun getOriginalBitmap(ctx: Context, resId: Int): Bitmap {        val options = BitmapFactory.Options()        options.inJustDecodeBounds = true //只解析原始图片的宽高，不decode原始文件装载到内存的Bitmap。        BitmapFactory.decodeResource(resources, resId, options)        //这一阶段，最关键的是获取原始图的真实宽高。        val srcBmpWidth = options.outWidth        val srcBmpHeight = options.outHeight        val d = ContextCompat.getDrawable(ctx, resId)        //根据原始图片的宽高创建一个空的Bitmap        val bitmap = Bitmap.createBitmap(srcBmpWidth, srcBmpHeight, Bitmap.Config.ARGB_8888)        val canvas = Canvas(bitmap)        d?.setBounds(0, 0, srcBmpWidth, srcBmpHeight)        d?.draw(canvas) //至此，bitmap即为原始图片。        return bitmap    }    override fun onTouchEvent(event: MotionEvent?): Boolean {        if (event == null) {            return false        }        mTouchX = event.x        mTouchY = event.y        when (event.action) {            MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> {                mCanDraw = true                myInvalidate()            }        }        return super.onTouchEvent(event)    }    private fun myInvalidate() {        this.invalidate()    }    fun setResultImage(iv: ImageView) {        result = iv    }    override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {        super.onSizeChanged(w, h, oldw, oldh)        W = w        H = h        Log.d("fly", "W=$W H=$H")    }    //从原始的Bitmap图中抠出一块SizeF大小的图。    private fun getCenterBmp(): Bitmap {        val bmp = Bitmap.createBitmap(W, H, Bitmap.Config.ARGB_8888)        val c = Canvas(bmp)        val dstRectF = RectF(0f, 0f, bmp.width.toFloat(), bmp.height.toFloat())        //需要特别注意，要把手指在屏幕上触点坐标，经过比例映射到原始图Bitmap的对应位置。        val mapToOriginBmpX = mOriginBmp!!.width * (mTouchX / W)        val mapToOriginBmpY = mOriginBmp!!.height * (mTouchY / H)        val centerRectF =            RectF(                mapToOriginBmpX - mSizeF.width / 2f,                mapToOriginBmpY - mSizeF.height / 2f,                mapToOriginBmpX + mSizeF.width / 2f,                mapToOriginBmpY + mSizeF.height / 2f            )        c.drawBitmap(mOriginBmp!!, centerRectF.toRect(), dstRectF, null)        val mx = Matrix()        mx.setScale(dstRectF.width() / centerRectF.width(), dstRectF.width() / centerRectF.width())        //下面图中的中心圆圈。        mPaint.color = Color.YELLOW        c.drawCircle(            W / 2f, H / 2f,            mx.mapRadius(mCircleRadius), //注意同步放大小图的圆圈半径。            mPaint        )        return bmp    }    override fun onDraw(canvas: Canvas) {        super.onDraw(canvas)        if (mCanDraw) {            //绘制中心圆圈。            mPaint.color = Color.YELLOW            canvas.drawCircle(mTouchX, mTouchY, mCircleRadius, mPaint)            drawRoundRectLine(canvas)            result?.setImageBitmap(getCenterBmp())            mCanDraw = false        }    }    private fun drawRoundRectLine(canvas: Canvas) {        val lineRectF = RectF(            0f,            0f,            mSizeF.width,            mSizeF.height        )        //原始图被Android系统拉伸放到屏幕上，所以lineRectF也需要进行相同的拉伸。        val originBmpSizeMapMatrix = Matrix()        originBmpSizeMapMatrix.setScale(getOriginBmpScaleToImageViewFactor(), getOriginBmpScaleToImageViewFactor())        originBmpSizeMapMatrix.mapRect(lineRectF)        lineRectF.offset(mTouchX - lineRectF.width() / 2f, mTouchY - lineRectF.height() / 2f)        //绘制红色的lineRectF线框。        val path = Path()        path.addRoundRect(lineRectF, 20f, 20f, Path.Direction.CW)        mPaint.color = Color.RED        canvas.drawPath(path, mPaint)    }    private fun getOriginBmpScaleToImageViewFactor(): Float {        return (W.toFloat()) / (mOriginBmp!!.width)    }}

运行后，点击上图不同位置点：

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