实现顶部圆角的自定义ImageView

Azadoo

已于 2024-07-22 10:24:54 修改

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文章标签： android kotlin

于 2024-07-19 17:24:29 首次发布

本文链接：https://blog.youkuaiyun.com/Azadoo/article/details/140555519

版权

package com.motorola.musicbox.view
import android.content.Context
import android.graphics.Bitmap
import android.graphics.BitmapShader
import android.graphics.Canvas
import android.graphics.Matrix
import android.graphics.Paint
import android.graphics.RectF
import android.graphics.Shader
import android.util.AttributeSet
import androidx.appcompat.widget.AppCompatImageView
import androidx.core.graphics.drawable.toBitmap

class TopRoundedImageView @JvmOverloads constructor(
    context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : AppCompatImageView(context, attrs, defStyleAttr) {

    private var cornerRadius = 24f // 圆角大小，单位为像素

    init {
        // 将圆角大小转换为像素
        cornerRadius = context.resources.displayMetrics.density * cornerRadius
    }

    private fun roundTopBitmapByShader(bitmap: Bitmap, outWidth: Int, outHeight: Int, radius: Float): Bitmap {
        val widthScale = outWidth.toFloat() / bitmap.width
        val heightScale = outHeight.toFloat() / bitmap.height
        val matrix = Matrix().apply {
            postScale(widthScale, heightScale)
        }

        val bitmapShader = BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP).apply {
            setLocalMatrix(matrix)
        }

        val targetBitmap = Bitmap.createBitmap(outWidth, outHeight, Bitmap.Config.ARGB_8888)
        val targetCanvas = Canvas(targetBitmap).apply {
            val paint = Paint().apply {
                isAntiAlias = true
                shader = bitmapShader
            }

            // 绘制顶部圆角
            drawRoundRect(RectF(0f, 0f, outWidth.toFloat(), (radius * 2).toFloat()), radius, radius, paint)

            // 绘制底部直角部分
            drawRect(RectF(0f, radius, outWidth.toFloat(), outHeight.toFloat()), paint)
        }

        return targetBitmap
    }

    override fun onDraw(canvas: Canvas) {
        val drawable = drawable ?: return
        val bitmap = drawable.toBitmap()
        val scaledBitmap = roundTopBitmapByShader(bitmap, width, height, cornerRadius)
        setImageBitmap(scaledBitmap)
        super.onDraw(canvas)
    }
}