面对让dragshaddow（由 DragShadowBuilder ）反应的东西，在拖动时发生的事情。

Faced the problem of letting the dragshaddow (created by a DragShadowBuilder) react on something, while dragging is happening.

难道有人知道应该如何办呢？

Do someone know how it supposed to be done?

推荐答案

下面是我的完整的code定制拖影生成器（依据定制拖影）。

Here's my complete code for custom drag shadow builder (gist for custom drag shadow).

然而，正如其他人提到有没有可能使用API​​-11引入了原生功能来修改拖影。

However, as others stated there is no possibility to modify drag shadow using native functionality introduced in API-11.

package com.marcingil.dragshadow;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Point;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.view.View;

public class ImageDragShadowBuilder extends View.DragShadowBuilder {
    private Drawable shadow;

    private ImageDragShadowBuilder() {
        super();
    }

    public static View.DragShadowBuilder fromResource(Context context, int drawableId) {
        ImageDragShadowBuilder builder = new ImageDragShadowBuilder();

        builder.shadow = context.getResources().getDrawable(drawableId);
        if (builder.shadow == null) {
            throw new NullPointerException("Drawable from id is null");
        }

        builder.shadow.setBounds(0, 0, builder.shadow.getMinimumWidth(), builder.shadow.getMinimumHeight());

        return builder;
    }

    public static View.DragShadowBuilder fromBitmap(Context context, Bitmap bmp) {
        if (bmp == null) {
            throw new IllegalArgumentException("Bitmap cannot be null");
        }

        ImageDragShadowBuilder builder = new ImageDragShadowBuilder();

        builder.shadow = new BitmapDrawable(context.getResources(), bmp);
        builder.shadow.setBounds(0, 0, builder.shadow.getMinimumWidth(), builder.shadow.getMinimumHeight());

        return builder;
    }

    @Override
    public void onDrawShadow(Canvas canvas) {
        shadow.draw(canvas);
    }

    @Override
    public void onProvideShadowMetrics(Point shadowSize, Point shadowTouchPoint) {
        shadowSize.x = shadow.getMinimumWidth();
        shadowSize.y = shadow.getMinimumHeight();

        shadowTouchPoint.x = (int)(shadowSize.x / 2);
        shadowTouchPoint.y = (int)(shadowSize.y / 2);
    }
}