带有阴影的自定义 ImageView [英] Custom ImageView with drop shadow

问题描述

好的，我一直在阅读和搜索，现在我正用头撞墙试图弄清楚这一点.到目前为止，这是我所拥有的:

Okay, I've been reading and searching around, and am now banging my head against the wall trying to figure this out. Here's what I have so far:

package com.pockdroid.sandbox;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.widget.ImageView;

public class ShadowImageView extends ImageView {

private Rect mRect;
private Paint mPaint;

public ShadowImageView(Context context)
{
    super(context);
    mRect = new Rect();
    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setShadowLayer(2f, 1f, 1f, Color.BLACK);
}

@Override
protected void onDraw(Canvas canvas) 
{
    Rect r = mRect;
    Paint paint = mPaint;

    canvas.drawRect(r, paint);
    super.onDraw(canvas);
}

@Override
protected void onMeasure(int w, int h)
{
    super.onMeasure(w,h);
    int mH, mW;
    mW = getSuggestedMinimumWidth() < getMeasuredWidth()? getMeasuredWidth() : getSuggestedMinimumWidth();
    mH = getSuggestedMinimumHeight() < getMeasuredHeight()? getMeasuredHeight() : getSuggestedMinimumHeight();
    setMeasuredDimension(mW + 5, mH + 5);
}

}

测量中的+5"是暂时的；据我了解，我需要做一些数学运算来确定阴影添加到画布的大小，对吧?

The "+5" in the measurements are there as temporary; From what I understand I'll need to do some math to determine the size that the drop shadow adds to the canvas, right?

但是当我使用这个时:

public View getView(int position, View convertView, ViewGroup parent) {
    ShadowImageView sImageView;
    if (convertView == null) {
        sImageView = new ShadowImageView(mContext);
        GridView.LayoutParams lp = new GridView.LayoutParams(85, 85);
        sImageView.setLayoutParams(lp);

        sImageView.setScaleType(ImageView.ScaleType.CENTER);
        sImageView.setPadding(5,5,5,5);
    } else {
        sImageView = (ShadowImageView) convertView;
    }

    sImageView.setImageBitmap(bitmapList.get(position));
    return sImageView;
}

在我的 ImageView 中，当我运行程序时，我仍然得到一个普通的 ImageView.

in my ImageView, I still get just a normal ImageView when I run the program.

有什么想法吗?谢谢.

所以我在 IRC 频道中与 RomainGuy 进行了交谈，我现在使用以下代码处理普通矩形图像.不过，它仍然不会将阴影直接绘制到我的位图透明度上，所以我仍在努力.

So I spoke with RomainGuy some in the IRC channel, and I have it working now for plain rectangular images with the below code. It still won't draw the shadow directly to my bitmap's transparency though, so I'm still working on that.

@Override
protected void onDraw(Canvas canvas) 
{
    Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.omen);
    Paint paint = new Paint();
    paint.setAntiAlias(true);
    paint.setShadowLayer(5.5f, 6.0f, 6.0f, Color.BLACK);
    canvas.drawColor(Color.GRAY);
    canvas.drawRect(50, 50, 50 + bmp.getWidth(), 50 + bmp.getHeight(), paint);
    canvas.drawBitmap(bmp, 50, 50, null);       
}

推荐答案

好吧，我没有预见到关于这个问题的更多答案，所以我现在最终选择的只是一个矩形图像的解决方案.我使用了以下 NinePatch:



以及 XML 中的适当填充:

Okay, I don't foresee any more answers on this one, so what I ended up going with for now is just a solution for rectangular images. I've used the following NinePatch:



along with the appropriate padding in XML:

<ImageView
        android:id="@+id/image_test"
        android:background="@drawable/drop_shadow"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:paddingLeft="6px"
        android:paddingTop="4px"
        android:paddingRight="8px"
        android:paddingBottom="9px"
        android:src="@drawable/pic1"
        />

要获得相当好的结果:



不理想，但可以.

to get a fairly good result:



Not ideal, but it'll do.

这篇关于带有阴影的自定义 ImageView的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！