问题描述

我正在编写 android 并且我有一个 imageview.我想将它的 scaletype 设置为 topcrop.我可以在选项中找到 centercrop，但这不是我的要求.我该怎么办?

I'm coding android and I have a imageview. I want to set scaletype of this to topcrop. I could find centercrop in options, but it's not my request. How do I do?

推荐答案

自定义 Android ImageView 用于对包含的 drawable 进行顶部裁剪.

Custom Android ImageView for top-crop scaling of the contained drawable.

import android.content.Context;
import android.graphics.Matrix;
import android.widget.ImageView;

/**
* ImageView to display top-crop scale of an image view.
*
* @author Chris Arriola
*/
public class TopCropImageView extends ImageView {

public TopCropImageView(Context context) {
    super(context);
    setScaleType(ScaleType.MATRIX);
}

@Override
protected boolean setFrame(int l, int t, int r, int b) {
    final Matrix matrix = getImageMatrix();

    float scale;
    final int viewWidth = getWidth() - getPaddingLeft() - getPaddingRight();
    final int viewHeight = getHeight() - getPaddingTop() - getPaddingBottom();
    final int drawableWidth = getDrawable().getIntrinsicWidth();
    final int drawableHeight = getDrawable().getIntrinsicHeight();

    if (drawableWidth * viewHeight > drawableHeight * viewWidth) {
        scale = (float) viewHeight / (float) drawableHeight;
    } else {
        scale = (float) viewWidth / (float) drawableWidth;
    }

    matrix.setScale(scale, scale);
    setImageMatrix(matrix);

    return super.setFrame(l, t, r, b);
}        
}

https://gist.github.com/arriolac/3843346

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