通过动态设置高度来裁剪图像

Posted 2023-02-25

【中文标题】通过动态设置高度来裁剪图像

【英文标题】：Cropping image by setting height dynamically

【发布时间】：2017-12-04 06:34:34

【问题描述】：

猜一个人的照片。 （头在上，腿在下）：P

我正在使用 layoutparam 动态设置高度。

当我将高度设置为 300 时，

它将高度从 HEAD 设置为 300 个单位到图像的腿。

我想要将高度从 LEG 设置为前 300 个单位。

imageView.setHeight()

【问题讨论】：

您需要使用指定的 (X,Y) 裁剪位图。见This。

是否可以将高度从 0（底部）设置为 100（顶部）。就像从 0 高度到 100% 高度显示图像视图一样。有可能吗？

高度将是相同的（300 或任何你想要的）。坐标会变化（X，Y）。

不，我不想改变坐标，因为我说过我想通过将高度 0 设置为 100% 来从底部到顶部开始显示 imageview。感谢您的快速回复。

如果符合您的要求，您可以使用 Reveal Animation。

【参考方案1】：

在你的 java 类中使用这个方法：

private void scaleImage(ImageView view) throws NoSuchElementException 
    // Get bitmap from the the ImageView.
    Bitmap bitmap = null;

    try 
        Drawable drawing = view.getDrawable();
        bitmap = ((BitmapDrawable) drawing).getBitmap();
     catch (NullPointerException e) 
        throw new NoSuchElementException("No drawable on given view");
     catch (ClassCastException e) 
        // Check bitmap is Ion drawable
//          bitmap = Ion.with(view).getBitmap();
    

    // Get current dimensions AND the desired bounding box
    int width = 0;

    try 
        width = bitmap.getWidth();
     catch (NullPointerException e) 
        throw new NoSuchElementException("Can't find bitmap on given view/drawable");
    

    int height = bitmap.getHeight();
    int bounding = dpToPx(150);// set height
    Logger.i("Test", "original width = " + Integer.toString(width));
    Logger.i("Test", "original height = " + Integer.toString(height));
    Logger.i("Test", "bounding = " + Integer.toString(bounding));

    // Determine how much to scale: the dimension requiring less scaling is
    // closer to the its side. This way the image always stays inside your
    // bounding box AND either x/y axis touches it.
    float xScale = ((float) bounding) / width;
    float yScale = ((float) bounding) / height;
    float scale = (xScale <= yScale) ? xScale : yScale;
    Logger.i("Test", "xScale = " + Float.toString(xScale));
    Logger.i("Test", "yScale = " + Float.toString(yScale));
    Logger.i("Test", "scale = " + Float.toString(scale));

    // Create a matrix for the scaling and add the scaling data
    Matrix matrix = new Matrix();
    matrix.postScale(scale, scale);

    // Create a new bitmap and convert it to a format understood by the ImageView
    Bitmap scaledBitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);
    width = scaledBitmap.getWidth(); // re-use
    height = scaledBitmap.getHeight(); // re-use
    BitmapDrawable result = new BitmapDrawable(scaledBitmap);
    Logger.i("Test", "scaled width = " + Integer.toString(width));
    Logger.i("Test", "scaled height = " + Integer.toString(height));

    // Apply the scaled bitmap
    view.setImageDrawable(result);

    // Now change ImageView's dimensions to match the scaled image
    LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) view.getLayoutParams();
    params.width = width;
    params.height = height;
    view.setLayoutParams(params);

    Logger.i("Test", "done");
    

    private int dpToPx(int dp) 
    float density = getApplicationContext().getResources().getDisplayMetrics().density;
    return Math.round((float) dp * density);
    

现在，如何调用这个方法：

        Bitmap bitmap;

            try 
                bitmap = MediaStore.Images.Media.getBitmap(getContentResolver(), selectedImage);
                imageView.setImageBitmap(bitmap);
                scaleImage(imageView);// call your imageview
             catch (IOException e) 
                e.printStackTrace();