Personnalisé ImageView avec ombre portée

Ceci est pris à partir de Romain Guy de présentation à Devoxx, pdf ici.

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);

Espère que cette aide.

NOTES

1. N'oubliez pas de Nid d'abeille et au-dessus, vous devez invoquer
   setLayerType(LAYER_TYPE_SOFTWARE, mShadow), sinon vous ne verrez pas votre ombre! (@Dmitriy_Boichenko)
2. SetShadowLayer n'
   ne pas travailler avec l'accélération matérielle, malheureusement, il a grandement
   réduit les performances (@Matt Usure) [1] [2]

Mon sale solution:

private static Bitmap getDropShadow3(Bitmap bitmap) {
if (bitmap==null) return null;
int think = 6;
int w = bitmap.getWidth();
int h = bitmap.getHeight();
int newW = w - (think);
int newH = h - (think);
Bitmap.Config conf = Bitmap.Config.ARGB_8888;
Bitmap bmp = Bitmap.createBitmap(w, h, conf);
Bitmap sbmp = Bitmap.createScaledBitmap(bitmap, newW, newH, false);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
Canvas c = new Canvas(bmp);
//Right
Shader rshader = new LinearGradient(newW, 0, w, 0, Color.GRAY, Color.LTGRAY, Shader.TileMode.CLAMP);
paint.setShader(rshader);
c.drawRect(newW, think, w, newH, paint);
//Bottom
Shader bshader = new LinearGradient(0, newH, 0, h, Color.GRAY, Color.LTGRAY, Shader.TileMode.CLAMP);
paint.setShader(bshader);
c.drawRect(think, newH, newW  , h, paint);
//Corner
Shader cchader = new LinearGradient(0, newH, 0, h, Color.LTGRAY, Color.LTGRAY, Shader.TileMode.CLAMP);
paint.setShader(cchader);
c.drawRect(newW, newH, w  , h, paint);
c.drawBitmap(sbmp, 0, 0, null);
return bmp;
}

résultat:

J'ai réussi à appliquer le dégradé de la frontière à l'aide de ce code..

public static Bitmap drawShadow(Bitmap bitmap, int leftRightThk, int bottomThk, int padTop) {
int w = bitmap.getWidth();
int h = bitmap.getHeight();
int newW = w - (leftRightThk * 2);
int newH = h - (bottomThk + padTop);
Bitmap.Config conf = Bitmap.Config.ARGB_8888;
Bitmap bmp = Bitmap.createBitmap(w, h, conf);
Bitmap sbmp = Bitmap.createScaledBitmap(bitmap, newW, newH, false);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
Canvas c = new Canvas(bmp);
//Left
int leftMargin = (leftRightThk + 7)/2;
Shader lshader = new LinearGradient(0, 0, leftMargin, 0, Color.TRANSPARENT, Color.BLACK, TileMode.CLAMP);
paint.setShader(lshader);
c.drawRect(0, padTop, leftMargin, newH, paint); 
//Right
Shader rshader = new LinearGradient(w - leftMargin, 0, w, 0, Color.BLACK, Color.TRANSPARENT, TileMode.CLAMP);
paint.setShader(rshader);
c.drawRect(newW, padTop, w, newH, paint);
//Bottom
Shader bshader = new LinearGradient(0, newH, 0, bitmap.getHeight(), Color.BLACK, Color.TRANSPARENT, TileMode.CLAMP);
paint.setShader(bshader);
c.drawRect(leftMargin -3, newH, newW + leftMargin + 3, bitmap.getHeight(), paint);
c.drawBitmap(sbmp, leftRightThk, 0, null);
return bmp;
}

espérons que cette aide !

Ici la mise en Œuvre de Paul Burkes réponse:

public class ShadowImageView extends ImageView {
public ShadowImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public ShadowImageView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public ShadowImageView(Context context) {
super(context);
}
private Paint createShadow() {
Paint mShadow = new Paint();
float radius = 10.0f;
float xOffset = 0.0f;
float yOffset = 2.0f;
//color=black
int color = 0xFF000000;
mShadow.setShadowLayer(radius, xOffset, yOffset, color);
return mShadow;
}
@Override
protected void onDraw(Canvas canvas) {
Paint mShadow = createShadow();
Drawable d = getDrawable();
if (d != null){
setLayerType(LAYER_TYPE_SOFTWARE, mShadow);
Bitmap bitmap = ((BitmapDrawable) getDrawable()).getBitmap();
canvas.drawBitmap(bitmap, 0.0f, 0.0f, mShadow);
} else {
super.onDraw(canvas);
}
};
}

TODO:
exécuter setLayerType(LAYER_TYPE_SOFTWARE, mShadow); seulement si l'API de Niveau > 10

Utiliser cette classe pour dessiner l'ombre sur les bitmaps

public class ShadowGenerator {
//Percent of actual icon size
private static final float HALF_DISTANCE = 0.5f;
public static final float BLUR_FACTOR = 0.5f/48;
//Percent of actual icon size
private static final float KEY_SHADOW_DISTANCE = 1f/48;
public static final int KEY_SHADOW_ALPHA = 61;
public static final int AMBIENT_SHADOW_ALPHA = 30;
private static final Object LOCK = new Object();
//Singleton object guarded by {@link #LOCK}
private static ShadowGenerator sShadowGenerator;
private  int mIconSize;
private final Canvas mCanvas;
private final Paint mBlurPaint;
private final Paint mDrawPaint;
private final Context mContext;
private ShadowGenerator(Context context) {
mContext = context;
mIconSize = Utils.convertDpToPixel(context,63);
mCanvas = new Canvas();
mBlurPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
mBlurPaint.setMaskFilter(new BlurMaskFilter(mIconSize * BLUR_FACTOR, Blur.NORMAL));
mDrawPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
}
public synchronized Bitmap recreateIcon(Bitmap icon) {
mIconSize = Utils.convertDpToPixel(mContext,3)+icon.getWidth();
int[] offset = new int[2];
Bitmap shadow = icon.extractAlpha(mBlurPaint, offset);
Bitmap result = Bitmap.createBitmap(mIconSize, mIconSize, Config.ARGB_8888);
mCanvas.setBitmap(result);
//Draw ambient shadow
mDrawPaint.setAlpha(AMBIENT_SHADOW_ALPHA);
mCanvas.drawBitmap(shadow, offset[0], offset[1], mDrawPaint);
//Draw key shadow
mDrawPaint.setAlpha(KEY_SHADOW_ALPHA);
mCanvas.drawBitmap(shadow, offset[0], offset[1] + KEY_SHADOW_DISTANCE * mIconSize, mDrawPaint);
//Draw the icon
mDrawPaint.setAlpha(255);
mCanvas.drawBitmap(icon, 0, 0, mDrawPaint);
mCanvas.setBitmap(null);
return result;
}
public static ShadowGenerator getInstance(Context context) {
synchronized (LOCK) {
if (sShadowGenerator == null) {
sShadowGenerator = new ShadowGenerator(context);
}
}
return sShadowGenerator;
}
}