使用Kotlin实现电子签名

使用Kotlin实现电子签名

​​Kotlin Demo​​​ 使用Kotlin实现了电子签名，用Kotlin写Android应用真是舒服。 我自定义了一个SignatureView:

package com.wong.testpimport android.annotation.SuppressLintimport android.content.Contextimport android.graphics.*import android.util.AttributeSetimport android.util.Base64import android.view.MotionEventimport android.view.Viewimport java.io.ByteArrayOutputStreamimport kotlin.math.absclass SignatureView : View { companion object { fun saveBitmapToBase64(bitmap: Bitmap):String{ val baos = ByteArrayOutputStream() bitmap.compress(Bitmap.CompressFormat.JPEG,100,baos) baos.flush() baos.close() return Base64.encodeToString(baos.toByteArray(),Base64.NO_WRAP) } fun base64ToBitmap(base64:String):Bitmap{ val bytes = Base64.decode(base64,Base64.NO_WRAP) return BitmapFactory.decodeByteArray(bytes,0,bytes.size) } } var mPathPaint: Paint = Paint(Paint.ANTI_ALIAS_FLAG) // 笔划画笔 lateinit var canvas: Canvas // 画布 private lateinit var mPath: Path // 记录在屏幕上触摸移动时的点组成的路径 private var mPreX: Float = 0.0f // 记录x坐标 private var mPreY: Float = 0.0f // 记录y坐标 private val touchTolerance:Float = 4F // 两点之间的差 init { mPathPaint.isAntiAlias = true mPathPaint.isDither = true mPathPaint.style = Paint.Style.STROKE mPathPaint.strokeJoin = Paint.Join.ROUND mPathPaint.strokeCap = Paint.Cap.ROUND mPathPaint.strokeWidth = 10F mPathPaint.color = Color.BLACK } constructor(context: Context) : super(context) {} constructor(context: Context, attrs: AttributeSet) : super(context, attrs) {} constructor(context: Context, attrs: AttributeSet, defStyleAttr: Int) : super(context, attrs, defStyleAttr) {} constructor(context: Context, attrs: AttributeSet, defStyleAttr: Int, defStyleRes: Int) : super(context, attrs, defStyleAttr, defStyleRes) {} @SuppressLint("DrawAllocation") override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) { super.onMeasure(widthMeasureSpec, heightMeasureSpec) mPath = Path() canvas = Canvas() } @SuppressLint("ClickableViewAccessibility") override fun onTouchEvent(event: MotionEvent?): Boolean { when(event?.action){ MotionEvent.ACTION_DOWN->{ mPreX = event.x mPreY = event.y mPath.moveTo(mPreX, mPreY) } MotionEvent.ACTION_MOVE->{ val x = event.x val y = event.y val dx = abs(mPreX-x) val dy = abs(mPreY - y) if(dx >= touchTolerance || dy >= touchTolerance){ mPath.quadTo(mPreX,mPreY,(x+mPreX)/2,(y+mPreY)/2) mPreX = event.x mPreY = event.y } } MotionEvent.ACTION_UP->{ mPath.lineTo(event.x,event.y) canvas.drawPath(mPath,mPathPaint) } } invalidate() return true } override fun onDraw(canvas: Canvas?) { super.onDraw(canvas) canvas?.drawPath(mPath,mPathPaint) } fun reset(){ mPath = Path() canvas = Canvas() invalidate() } val mBitmap:Bitmap? get() { val bitmap = Bitmap.createBitmap(width,height,Bitmap.Config.ARGB_8888) val canvas = Canvas(bitmap) if(background != null){ background.draw(canvas) }else{ canvas.drawColor(Color.WHITE) draw(canvas) } return bitmap }}

使用伴生对象提供了两个方法，一个是将Bitmap转Base64，另一个是将Base64字符串转成Bitmap。

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