android - 固定纵横比 View

Question

我将如何实现一个固定的纵横比View？我想在 GridView 中有 1:1 纵横比的项目。我认为子类化子类比 GridView 更好？

编辑:我认为这需要以编程方式完成，这没问题。另外，我不想限制大小，只限制纵横比。

Answer 1

我实现了 FixedAspectRatioFrameLayout，因此我可以重用它并使任何托管 View 具有固定的纵横比:

public class FixedAspectRatioFrameLayout extends FrameLayout
{
    private int mAspectRatioWidth;
    private int mAspectRatioHeight;

    public FixedAspectRatioFrameLayout(Context context)
    {
        super(context);
    }

    public FixedAspectRatioFrameLayout(Context context, AttributeSet attrs)
    {
        super(context, attrs);

        init(context, attrs);
    }

    public FixedAspectRatioFrameLayout(Context context, AttributeSet attrs, int defStyle)
    {
        super(context, attrs, defStyle);

        init(context, attrs);
    }

    private void init(Context context, AttributeSet attrs)
    {
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.FixedAspectRatioFrameLayout);

        mAspectRatioWidth = a.getInt(R.styleable.FixedAspectRatioFrameLayout_aspectRatioWidth, 4);
        mAspectRatioHeight = a.getInt(R.styleable.FixedAspectRatioFrameLayout_aspectRatioHeight, 3);

        a.recycle();
    }
    // **overrides**

    @Override protected void onMeasure (int widthMeasureSpec, int heightMeasureSpec)
    {
        int originalWidth = MeasureSpec.getSize(widthMeasureSpec);

        int originalHeight = MeasureSpec.getSize(heightMeasureSpec);

        int calculatedHeight = originalWidth * mAspectRatioHeight / mAspectRatioWidth;

        int finalWidth, finalHeight;

        if (calculatedHeight > originalHeight)
        {
            finalWidth = originalHeight * mAspectRatioWidth / mAspectRatioHeight; 
            finalHeight = originalHeight;
        }
        else
        {
            finalWidth = originalWidth;
            finalHeight = calculatedHeight;
        }

        super.onMeasure(
                MeasureSpec.makeMeasureSpec(finalWidth, MeasureSpec.EXACTLY), 
                MeasureSpec.makeMeasureSpec(finalHeight, MeasureSpec.EXACTLY));
    }
}