Android基于Matrix绘制PaintDrawable设置BitmapShader，以手指触点为中心显示原图像圆图，Kotlin（2）

在 https://zhangphil.blog.csdn.net/article/details/135374279 基础上，增加一个功能，当手指在上面的图片上滑动时候，显示滑动轨迹：

Kotlin 复制代码

import android.content.Context
import android.graphics.Bitmap
import android.graphics.BitmapShader
import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Matrix
import android.graphics.Paint
import android.graphics.Path
import android.graphics.Shader.TileMode
import android.graphics.drawable.BitmapDrawable
import android.graphics.drawable.PaintDrawable
import android.os.Bundle
import android.util.AttributeSet
import android.util.Log
import android.view.MotionEvent
import android.widget.ImageView
import androidx.appcompat.app.AppCompatActivity
import androidx.appcompat.widget.AppCompatImageView


class MainActivity : AppCompatActivity() {
    private var iv: MyImageView? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        iv = findViewById(R.id.iv)

        val r = findViewById<ImageView>(R.id.result)
        iv?.setTestImageView(r)
    }
}

class MyImageView : AppCompatImageView {
    private var mCurX = 0
    private var mCurY = 0

    private val mPath = Path()
    private val mPathPaint = Paint()

    private var mNewBmp: Bitmap? = null
    private var mSrcBmp: Bitmap? = null
    private var mIsDraw = false
    private val mRadius = 300f

    private var mDrawable: PaintDrawable? = null

    private var testIV: ImageView? = null

    constructor(ctx: Context, attrs: AttributeSet) : super(ctx, attrs) {
        mSrcBmp = (drawable as BitmapDrawable).bitmap

        mPathPaint.style = Paint.Style.STROKE
        mPathPaint.strokeWidth = 15f
        mPathPaint.isAntiAlias = true
        mPathPaint.color = Color.RED
    }

    fun setTestImageView(iv: ImageView?) {
        testIV = iv
    }

    override fun onTouchEvent(event: MotionEvent): Boolean {
        mCurX = event.x.toInt()
        mCurY = event.y.toInt()

        when (event.action) {
            MotionEvent.ACTION_DOWN -> {
                Log.d("fly", "开始绘制")

                mPath.moveTo(event.x, event.y)

                mIsDraw = true
            }

            MotionEvent.ACTION_MOVE -> {
                mPath.lineTo(event.x, event.y)
            }

            MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> {
                Log.d("fly", "不需绘制")
                mIsDraw = false

                //抬手后，清除手指轨迹。
                myClear()
            }
        }

        invalidate()

        return true
    }

    private fun myClear() {
        //清除历史轨迹。
        mPath.reset()
    }

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

        if (mIsDraw) {
            myDraw()

            canvas.drawPath(mPath, mPathPaint)
        }
    }

    private fun myDraw() {
        val shader = BitmapShader(Bitmap.createScaledBitmap(mSrcBmp!!, this.width, this.height, true), TileMode.DECAL, TileMode.DECAL)
        mDrawable = PaintDrawable(Color.DKGRAY)
        mDrawable!!.setCornerRadius(mRadius / 2) //圆角矩形，如果不除2即是圆形框图。
        mDrawable!!.paint.shader = shader
        mDrawable!!.setBounds(0, 0, (mRadius * 2).toInt(), (mRadius * 2).toInt())

        mNewBmp = Bitmap.createBitmap(this.width, this.height, Bitmap.Config.ARGB_8888)
        val c = Canvas(mNewBmp!!)
        c.drawColor(Color.LTGRAY) //画满底色。


        val matrix = Matrix()
        matrix.setTranslate(-mCurX + mRadius, -mCurY + mRadius)
        mDrawable!!.paint.shader.setLocalMatrix(matrix)

        mDrawable!!.draw(c)


        testIV?.setImageBitmap(mNewBmp)
    }
}

XML 复制代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/darker_gray"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <com.pkg.MyImageView
        android:id="@+id/iv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:adjustViewBounds="true"
        android:background="@drawable/ic_launcher_background"
        android:scaleType="fitCenter"
        android:src="@mipmap/mypic" />

    <ImageView
        android:id="@+id/result"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:background="@drawable/ic_launcher_background"
        android:src="@drawable/ic_launcher_foreground" />

</LinearLayout>

https://zhangphil.blog.csdn.net/article/details/135374279https://zhangphil.blog.csdn.net/article/details/135374279