Android基于Matrix绘制PaintDrawable设置BitmapShader，以手指触点为中心显示原图的圆切图，Kotlin（4）
这篇 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（3）-CSDN博客 虽然实现了上图绘制手指在屏幕滑动的轨迹，且在下面的切图中用中心圆圈标记出当前手指在图中的位置，但没有在下面的切图中也绘制出与上图的手指滑动轨迹，下面实现这个功能：手指在原图中滑动，在切图中用圆圈标记手指的位置，同时在切图中复刻手指滑动的轨迹。
Kotlin
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.RectF
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.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 mPath1 = Path()
private val mPath2 = Path()
private val mPathPaint1 = Paint()
private val mPathPaint2 = Paint()
private val mCirclePaint = 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
mPathPaint1.style = Paint.Style.STROKE
mPathPaint1.strokeWidth = 15f
mPathPaint1.isAntiAlias = true
mPathPaint1.color = Color.RED
mPathPaint2.style = Paint.Style.STROKE
mPathPaint2.strokeWidth = 20f
mPathPaint2.isAntiAlias = true
mPathPaint2.color = Color.YELLOW
mCirclePaint.style = Paint.Style.STROKE
mCirclePaint.strokeWidth = 25f
mCirclePaint.isAntiAlias = true
mCirclePaint.color = Color.BLUE
}
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 -> {
mPath1.moveTo(event.x, event.y)
mPath2.moveTo(event.x, event.y)
mIsDraw = true
}
MotionEvent.ACTION_MOVE -> {
mPath1.lineTo(event.x, event.y)
mPath2.lineTo(event.x, event.y)
}
MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> {
mIsDraw = false
//抬手后，清除手指轨迹。
myClear()
}
}
invalidate()
return true
}
private fun myClear() {
//清除历史轨迹。
mPath1.reset()
mPath2.reset()
}
override fun onDraw(canvas: Canvas) {
super.onDraw(canvas)
if (mIsDraw) {
myDraw()
canvas.drawPath(mPath1, mPathPaint1)
}
}
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)
val rectF = RectF()
matrix.mapRect(rectF)
val cx = mCurX + rectF.left
val cy = mCurY + rectF.top
c.drawCircle(cx, cy, 30f, mCirclePaint) //蓝色中心圆圈
//下面小框图里面的Path
val path = Path()
mPath2.transform(matrix, path)
c.drawPath(path, mPathPaint2) //绘制下面框图里面的Path
testIV?.setImageBitmap(mNewBmp)
}
}
XML
<?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>
有两个遗留问题：
1、手指滑动出有效取景区域后，切图还在显示，这不是很合理。
2、最好只把黄色的轨迹线约束在圆角矩形的小切图框里面，不要在下面的切图小框外显示多余的黄色轨迹线。