在列表视图旋转图像 [英] Rotating images in Listview

问题描述

我试图做一个假的ListView水平。对于这一点，我想要旋转在适配器的每个单元格的内容。它几乎作品：

I am trying to make a fake horizontal ListView. For that, I want to rotate the content of each cell in the adapter. It almost works:

class ImageAdapter(ctx: Context, viewResourceId: Int, imageResourceId: Int, strings: Array[String], icons: TypedArray, colorSelected: Int, colorNotSelected: Int, colorBorder: Int) extends ArrayAdapter[String](ctx, viewResourceId, strings) {
    // Useful variables
    private val mInflater: LayoutInflater = ctx.getSystemService(
                Context.LAYOUT_INFLATER_SERVICE).asInstanceOf[LayoutInflater]
    private val mStrings: Array[String] = strings
    private val mIcons: TypedArray = icons
    private val mViewResourceId: Int = viewResourceId

    private var mSelected : Int = 0

    def setSelected(s: Int) = mSelected = s

    // Inherited from ArrayAdapter
    override def getCount():Int = mStrings.length
    override def getItem(position: Int): String = mStrings(position)
    override def getItemId(position: Int): Long = position

    // The rotation machinery
    var rotation = 90
    private var matrix = new Matrix()
    val rect1 = new RectF(0, 0, 0, 0)
    val rect2 = new RectF(0, 0, 0, 0)
    val cst = Matrix.ScaleToFit.CENTER

    // Getting the view.
    override def getView(position: Int, convertView: View, parent: ViewGroup): View = {
        var result = if(convertView == null) mInflater.inflate(mViewResourceId, null) else convertView

        var iv: ImageView = result.findViewById(imageResourceId).asInstanceOf[ImageView]
        val drawable = mIcons.getDrawable(position)
        iv.setScaleType(ScaleType.MATRIX)
        matrix.reset()
        val height = drawable.getIntrinsicHeight()
        val width = drawable.getIntrinsicWidth()
        rotation match {
          case 0 =>
            rect1.set(0, 0, width, height)
            rect2.set(0, 0, iv.getWidth(), iv.getHeight())
            matrix.setRectToRect(rect1, rect2, cst)
          case 90 =>
            rect1.set(0, 0, width, height)
            rect2.set(-iv.getHeight()/2, -iv.getWidth()/2, iv.getHeight()/2, iv.getWidth()/2)
            matrix.setRectToRect(rect1, rect2, cst)
            matrix.postRotate(rotation, 0, 0)
            matrix.postTranslate(iv.getWidth()/2, iv.getHeight()/2)
          ...
          case _ =>
        }
        iv.setImageMatrix(matrix)
        iv.setImageDrawable(drawable)
        iv.postInvalidate()

        if(position == mSelected) {
          result.setBackgroundColor(colorSelected)
        } else {
          result.setBackgroundColor(colorNotSelected)
        }
        result.setTag(mStrings(position))
        result
    }
}

唯一的问题是，它不显示第一画面。相反，它会显示如下：

The only problem is that it does not display the first picture. Instead, it displays this:

有关出现在第一个列表，我需要单击每个列表中的一个元素。的onclick方法如下：

For the first list to appear, I need to click on one element of each list. The onclick method is the following:

listGraphismesView.setOnItemClickListener(new OnItemClickListener {
    override def onItemClick(parent: AdapterView[_], view: View, position: Int, notUsedId: Long) = {
      var graphismeName = view.getTag().asInstanceOf[String]
      mAdapter.setSelected(position)
      mAdapter.notifyDataSetChanged()
      showGChallenge(position, graphismeName)
    }
  })

我试图然后把mAdapter.notifyDataSetChanged（）中的片段的onResume功能，但它不更新从头列表。我还需要点击适合所有的图像出现。
任何想法，为什么？

I tried then to put mAdapter.notifyDataSetChanged() in the onResume function of the fragment, but it does not update the list from the beginning. I still need to click on something for all images to appear. Any idea why ?

推荐答案

我发现iv.getWidth（）和iv.getHeight（）均返回零，因为getview将由onActivityCreated函数被调用。把notifyDataSetChanged（）在onResume功能太早了。所以绘制将与大小为0绘制，当我可以点击按钮重新加载。

I found out that iv.getWidth() and iv.getHeight() were both returning zero because the getview would be called by the onActivityCreated function. Putting notifyDataSetChanged() in the onResume function was too early too. So the drawable would be drawn with size 0, and reloaded when I could click on the button.

因此​​，要改变这种状况，我写了下面一段code，呼吁调整大小功能的监听器。

So to change that, I wrote the following piece of code, calling the resize function with a listener.

var iv: ImageView = result.findViewById(imageResourceId).asInstanceOf[ImageView]
val drawable = mIcons.getDrawable(position)
iv.setImageDrawable(drawable)
iv.setScaleType(ScaleType.MATRIX)
val vto = iv.getViewTreeObserver()
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
  private var matrix = new Matrix()
  val rect1 = new RectF(0, 0, 0, 0)
  val rect2 = new RectF(0, 0, 0, 0)
  private var height = drawable.getIntrinsicHeight()
  private var width = drawable.getIntrinsicWidth()
  override def onGlobalLayout() {
    val iv_width = iv.getWidth
    val iv_height = iv.getHeight
    matrix.reset()
    rotation match {
      case 0 =>
        rect1.set(0, 0, width, height)
        rect2.set(0, 0, iv_width, iv_height)
        matrix.setRectToRect(rect1, rect2, cst)
      case 90 =>
        rect1.set(0, 0, width, height)
        rect2.set(-iv_height/2, -iv_width/2, iv_height/2, iv_width/2)
        matrix.setRectToRect(rect1, rect2, cst)
        matrix.postRotate(rotation, 0, 0)
        matrix.postTranslate(iv_width/2, iv_height/2)
      ...
      case _ =>
    }
    iv.setImageMatrix(matrix)
  }
})

这篇关于在列表视图旋转图像的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！