Android 通过View生成Bitmap

Android 通过View生成Bitmap

fun getBitmapByView(view: View?): Bitmap? {
    if (null == view) {
        return null
    }
    var bitmap: Bitmap? = null

    // 步骤一：获取视图的宽和高
    val width: Int = view.getRight() - view.getLeft()
    val height: Int = view.getBottom() - view.getTop()

    // 判断背景是否为不透明
    val opaque = view.getDrawingCacheBackgroundColor() !== 0 || view.isOpaque()
    val quality: Bitmap.Config
    quality = if (!opaque) {
        when (view.getDrawingCacheQuality()) {
            DRAWING_CACHE_QUALITY_AUTO, DRAWING_CACHE_QUALITY_LOW, DRAWING_CACHE_QUALITY_HIGH -> Bitmap.Config.ARGB_8888
            else -> Bitmap.Config.ARGB_8888
        }
    } else {
        Bitmap.Config.RGB_565
    }

    // 步骤二：生成bitmap
    bitmap = Bitmap.createBitmap(resources.displayMetrics, width, height, quality)
    bitmap.density = resources.displayMetrics.densityDpi
    if (opaque) {
        bitmap.setHasAlpha(false)
    }
    val clear = view.getDrawingCacheBackgroundColor() !== 0

    // 步骤三：绘制canvas
    val canvas = Canvas(bitmap)
    if (clear) {
        bitmap.eraseColor(view.getDrawingCacheBackgroundColor())
    }
    view.computeScroll()
    val restoreCount: Int = canvas.save()
    canvas.translate((-view.getScrollX()).toFloat(), (-view.getScrollY()).toFloat())
    view.draw(canvas)
    canvas.restoreToCount(restoreCount)
    canvas.setBitmap(null)
    return bitmap
}