Question

我的家庭自动化应用程序具有以下功能：人们可以使用可用于控制家庭自动化软件的平面图和仪表板将图像上传到手机。我让他们上传了两张图片：一张带有他们想要显示的图片的可见图像，另一张带有纯色的彩色图，对应于他们想要从可见图像中定位区域的对象。两个图像必须具有相同的大小，以像素为单位。当他们点击屏幕时，我希望能够从colormap覆盖图中获取颜色，然后我继续执行与该颜色相关联的操作。问题是，图像的缩放让我感到困惑。他们使用的图像可能比设备屏幕大，所以我缩放它们以便它们适合显示器。我现在不需要捏缩放功能，但我可能会在以后实现它。现在，我只想让图像以最大尺寸显示，以便它适合屏幕。所以，我的问题是，我怎么能修改这个代码，以便我可以从缩放的图像中获得正确的接触点颜色。图像缩放本身似乎工作正常。它被缩放并正确显示。我只是无法获得正确的接触点。

 final Bitmap bm = decodeSampledBitmapFromFile(visible_image, size, size);
 if (bm!=null) {
    imageview.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
    imageview.setImageBitmap(bm);
 }

 final Bitmap bm2 = decodeSampledBitmapFromFile(image_overlay, size, size);
 if (bm2!=null) {
    overlayimageview.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
    overlayimageview.setImageBitmap(bm2);

    imageview.setOnTouchListener(new OnTouchListener() {

        @Override
        public boolean onTouch(View v, MotionEvent mev) {
            DecodeActionDownEvent(v, mev, bm2);
            return false;
        }

    });
 }

 private void DecodeActionDownEvent(View v, MotionEvent ev, Bitmap bm2)
 {
    xCoord = Integer.valueOf((int)ev.getRawX());
    yCoord = Integer.valueOf((int)ev.getRawY());
    try {
        // Here's where the trouble is.
        // returns the value of the unscaled pixel at the scaled touch point?
        colorTouched = bm2.getPixel(xCoord, yCoord); 
    } catch (IllegalArgumentException e) {
        colorTouched = Color.WHITE; // nothing happens when touching white
    }
 }

 private static Bitmap decodeSampledBitmapFromFile(String fileName, 
         int reqWidth, int reqHeight) {
     // code from 
     // http://developer.android.com/training/displaying-bitmaps/load-bitmap.html
     final BitmapFactory.Options options = new BitmapFactory.Options();
     options.inJustDecodeBounds = true;
     BitmapFactory.decodeFile(fileName, options);

     // Calculate inSampleSize
     options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

     // Decode bitmap with inSampleSize set
     options.inJustDecodeBounds = false;
     return BitmapFactory.decodeFile(fileName, options);
 }

 private static int calculateInSampleSize(
      BitmapFactory.Options options, int reqWidth, int reqHeight) {
     // code from 
     // http://developer.android.com/training/displaying-bitmaps/load-bitmap.html
     // Raw height and width of image
     final int height = options.outHeight;
     final int width = options.outWidth;
     int inSampleSize = 1;

     if (height > reqHeight || width > reqWidth) {
       if (width > height) {
          inSampleSize = Math.round((float)height / (float)reqHeight);
       } else {
          inSampleSize = Math.round((float)width / (float)reqWidth);
       }
     }
     return inSampleSize;
 }

Answer 1

我明白了。我换了

 xCoord = Integer.valueOf((int)ev.getRawX());
 yCoord = Integer.valueOf((int)ev.getRawY());

与

 Matrix inverse = new Matrix();
 v.getImageMatrix().invert(inverse);
 float[] touchPoint = new float[] {ev.getX(), ev.getY()};
 inverse.mapPoints(touchPoint);
 xCoord = Integer.valueOf((int)touchPoint[0]);
 yCoord = Integer.valueOf((int)touchPoint[1]);

Answer 2

7年后，我必须提供另一个答案，因为从LG G6升级到LG G8后，接受答案中的代码停止返回正确的颜色。

此解决方案可以在我在家中找到的所有电话上使用，但是谁知道...也许这甚至不是通用的。

（使用Xamarin C＃，但原理很容易理解）

首先，我们必须将实际ImageView的大小设为float才能进行浮点除法

private float imageSizeX;
private float imageSizeY;

private void OnCreate(...) {
    ...
    FindViewById<ImageView>(Resource.Id.colpick_Image).LayoutChange += OnImageLayout;
    FindViewById<ImageView>(Resource.Id.colpick_Image).Touch += Image_Touch;
    ...
}

//Event called every time the layout of our ImageView is updated
private void OnImageLayout(object sender, View.LayoutChangeEventArgs e) {
    imageSizeX = Image.Width;
    imageSizeY = Image.Height;
    Image.LayoutChange -= OnImageLayout; //Just need it once then unsubscribe
}

//Called every time user touches/is touching the ImageView
private void Image_Touch(object sender, View.TouchEventArgs e) {
    MotionEvent m = e.Event;

    ImageView img = sender as ImageView;

    int x = Convert.ToInt32(m.GetX(0));
    int y = Convert.ToInt32(m.GetY(0));

    Bitmap bmp = (img.Drawable as BitmapDrawable).Bitmap;

    // The scale value (how many times is the image bigger)
    // I only use it with images where Width == Height, so I get
    // scaleX == scaleY
    float scaleX = bmp.Width / imageSizeX;
    float scaleY = bmp.Height / imageSizeY;

    x = (int)(x * scaleX);
    y = (int)(y * scaleY);

    // Check for invalid values/outside of image bounds etc...

    // Get the correct Color ;)
    int color = bmp.GetPixel(x, y);
}

Android imageview从缩放图像中获取像素颜色

2 个答案: