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。
Kotlin
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.withContext
class MainActivity : AppCompatActivity() {
private var iv: ImageView? = null
private var result: ImageView? = null
override 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 / step
val deltaH: Float = height / step
CoroutineScope(Dispatchers.IO).launch {
var w = 0f
var h = 0f
for (i in 0 until step.toInt()) {
delay(delayTime)
w += deltaW
h += deltaH
val 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/135961734