Android用setRectToRect实现Bitmap基于Matrix矩阵scale缩放RectF动画，Kotlin（一）

基于Matrix，控制Bitmap的setRectToRect的目标RectF的宽高。从很小的宽高开始，不断迭代增加setRectToRect的目标RectF的宽高，每次迭代加上一定时延，实现Matrix基础上的动画。

import android.graphics.Bitmap
import android.graphics.BitmapFactory
import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Matrix
import android.graphics.RectF
import android.os.Bundle
import android.widget.ImageView
import androidx.appcompat.app.AppCompatActivity
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContextclass MainActivity : AppCompatActivity() {private var iv: ImageView? = nullprivate var result: ImageView? = nulloverride fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)setContentView(R.layout.activity_main)iv = findViewById(R.id.iv)result = findViewById(R.id.result)}override fun onResume() {super.onResume()result?.postDelayed({val bmp = BitmapFactory.decodeResource(resources, R.mipmap.mypic)matrixAnimScale(bmp, iv!!.width, iv!!.height)}, 500)}private fun matrixAnimScale(srcBmp: Bitmap, width: Int, height: Int) {val delayTime = 1L //动画之间的间隔。val step = 100f //100次缩放绘制，每步延时delayTime毫秒，总计 delayTime*step 毫秒完成动画。val deltaW: Float = width / stepval deltaH: Float = height / stepCoroutineScope(Dispatchers.IO).launch {var w = 0fvar h = 0ffor (i in 0 until step.toInt()) {delay(delayTime)w += deltaWh += deltaHval bmp = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888)val c = Canvas(bmp)c.drawColor(Color.BLUE)val src = RectF(0f, 0f, srcBmp.width.toFloat(), srcBmp.height.toFloat())val dst = RectF(0f, 0f, w, h)val mx = Matrix()mx.setRectToRect(src, dst, Matrix.ScaleToFit.CENTER)c.drawBitmap(srcBmp, mx, null)withContext(Dispatchers.Main) {result?.setImageBitmap(bmp)}}}}
}

上下两个ImageView，下面的ImageView展示从小到大不断放大的Bitmap（与上方的ImageView展示的Bitmap一样）:

最终动画结束：

https://zhangphil.blog.csdn.net/article/details/135961734https://zhangphil.blog.csdn.net/article/details/135961734

Android矩阵setRectToRect裁剪Bitmap原图Matrix放大，mapRect标记中心区域，Kotlin-CSDN博客文章浏览阅读180次。【代码】Android矩阵setRectToRect裁剪Bitmap原图Matrix放大，mapRect标记中心区域，Kotlin。https://blog.csdn.net/zhangphil/article/details/135960921