Android uses setRectToRect to implement Bitmap scaling RectF animation based on Matrix matrix scale, Kotlin (1)

Android uses setRectToRect to implement Bitmap scaling RectF animation based on Matrix matrix scale, Kotlin (1)

 

Based on Matrix, control the width and height of the target RectF of Bitmap's setRectToRect. Starting from a very small width and height, iteratively increases the width and height of the target RectF of setRectToRect, adding a certain delay to each iteration to achieve animation based on Matrix.

 

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)
                }
            }
        }
    }
}

 

 

 

 

There are two ImageViews above and below. The ImageView below displays a Bitmap that is continuously enlarged from small to large (the same as the Bitmap displayed by the ImageView above):

 

The final animation ends: 

 

 

 

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

Android matrix setRectToRect crops the original Bitmap Matrix and enlarges it, mapRect marks the center area, and the Kotlin-CSDN blog article has been viewed 180 times. [Code] Android matrix setRectToRect crops the Bitmap original image Matrix and enlarges it, mapRect marks the center area, Kotlin. https://blog.csdn.net/zhangphil/article/details/135960921

https://zhangphil.blog.csdn.net/article/details/135913218https://zhangphil.blog.csdn.net/article/details/135913218