Android:如何在保持纵横比的同时将图像拉伸到屏幕宽度? [英] Android: How to stretch an image to the screen width while maintaining aspect ratio?

问题描述

我想下载一张图片(尺寸未知，但始终大致为正方形)并显示它，使其水平填充屏幕，并在任何屏幕尺寸上垂直拉伸以保持图像的纵横比.这是我的(非工作)代码.它水平拉伸图像，而不是垂直拉伸，所以它被压扁了...

I want to download an image (of unknown size, but which is always roughly square) and display it so that it fills the screen horizontally, and stretches vertically to maintain the aspect ratio of the image, on any screen size. Here is my (non-working) code. It stretches the image horizontally, but not vertically, so it is squashed...

ImageView mainImageView = new ImageView(context);
    mainImageView.setImageBitmap(mainImage); //downloaded from server
    mainImageView.setScaleType(ScaleType.FIT_XY);
    //mainImageView.setAdjustViewBounds(true); 
    //with this line enabled, just scales image down
    addView(mainImageView,new LinearLayout.LayoutParams( 
            LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));

推荐答案

我使用自定义视图完成了这项工作.设置 layout_width="fill_parent" 和 layout_height="wrap_content"，并将其指向适当的可绘制对象:

I accomplished this with a custom view. Set layout_width="fill_parent" and layout_height="wrap_content", and point it to the appropriate drawable:

public class Banner extends View {

  private final Drawable logo;

  public Banner(Context context) {
    super(context);
    logo = context.getResources().getDrawable(R.drawable.banner);
    setBackgroundDrawable(logo);
  }

  public Banner(Context context, AttributeSet attrs) {
    super(context, attrs);
    logo = context.getResources().getDrawable(R.drawable.banner);
    setBackgroundDrawable(logo);
  }

  public Banner(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    logo = context.getResources().getDrawable(R.drawable.banner);
    setBackgroundDrawable(logo);
  }

  @Override protected void onMeasure(int widthMeasureSpec,
      int heightMeasureSpec) {
    int width = MeasureSpec.getSize(widthMeasureSpec);
    int height = width * logo.getIntrinsicHeight() / logo.getIntrinsicWidth();
    setMeasuredDimension(width, height);
  }
}

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