Custom ImageView with drop shadow
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);
}
}
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?
But when I use this:
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;
}
in my ImageView, I still get just a normal ImageView when I run the program.
Any thoughts? Thanks.
EDIT: 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);
}
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"
/>
to get a fairly good result:
Not ideal, but it'll do.
This is taken from Romain Guy's presentation at Devoxx, pdf found here.
Paint mShadow = new Paint();
// radius=10, y-offset=2, color=black
mShadow.setShadowLayer(10.0f, 0.0f, 2.0f, 0xFF000000);
// in onDraw(Canvas)
canvas.drawBitmap(bitmap, 0.0f, 0.0f, mShadow);
Hope this helps.
NOTES
setLayerType(LAYER_TYPE_SOFTWARE, mShadow)
, otherwise you will not see your shadow! (@Dmitriy_Boichenko) SetShadowLayer
does not work with hardware acceleration unfortunately so it greatly reduces performances (@Matt Wear) [1] [2] 我相信UIFuel的这个答案
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<!-- Drop Shadow Stack -->
<item>
<shape>
<padding android:top="1dp" android:right="1dp" android:bottom="1dp" android:left="1dp" />
<solid android:color="#00CCCCCC" />
</shape>
</item>
<item>
<shape>
<padding android:top="1dp" android:right="1dp" android:bottom="1dp" android:left="1dp" />
<solid android:color="#10CCCCCC" />
</shape>
</item>
<item>
<shape>
<padding android:top="1dp" android:right="1dp" android:bottom="1dp" android:left="1dp" />
<solid android:color="#20CCCCCC" />
</shape>
</item>
<item>
<shape>
<padding android:top="1dp" android:right="1dp" android:bottom="1dp" android:left="1dp" />
<solid android:color="#30CCCCCC" />
</shape>
</item>
<item>
<shape>
<padding android:top="1dp" android:right="1dp" android:bottom="1dp" android:left="1dp" />
<solid android:color="#50CCCCCC" />
</shape>
</item>
<!-- Background -->
<item>
<shape>
<solid android:color="@color/white" />
<corners android:radius="3dp" />
</shape>
</item>
</layer-list>
链接地址: http://www.djcxy.com/p/5314.html
上一篇: 列表视图的曲线边框
下一篇: 带阴影的自定义ImageView