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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）

news 2025/8/6 11:13:32

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：

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.AppCompatImageViewclass MainActivity : AppCompatActivity() {private var iv: MyImageView? = nulloverride 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 = 0private var mCurY = 0private val mPath = Path()private val mPathPaint = Paint()private var mNewBmp: Bitmap? = nullprivate var mSrcBmp: Bitmap? = nullprivate var mIsDraw = falseprivate val mRadius = 300fprivate var mDrawable: PaintDrawable? = nullprivate var testIV: ImageView? = nullconstructor(ctx: Context, attrs: AttributeSet) : super(ctx, attrs) {mSrcBmp = (drawable as BitmapDrawable).bitmapmPathPaint.style = Paint.Style.STROKEmPathPaint.strokeWidth = 15fmPathPaint.isAntiAlias = truemPathPaint.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 = shadermDrawable!!.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 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.MyImageViewandroid: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" /><ImageViewandroid: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