Launcher 读取第三方图标颜色添加相应的背景

因为 android的第三方图标不规则，公司这边会要求统一加一个标准背板。但是如果所有的图标都加一个会显得单调，所以我采用读取第三方图标的颜色，然后添加相应的背景。

修改图标背景的文件是在Launcher3文件夹下的Utilities.java下的 createIconBitmap 函数里，原始函数为：

    public static Bitmap createIconBitmap(Drawable icon, Context context) {
        synchronized (sCanvas) {
            final int iconBitmapSize = getIconBitmapSize();

            int width = iconBitmapSize;
            int height = iconBitmapSize;

            if (icon instanceof PaintDrawable) {
                PaintDrawable painter = (PaintDrawable) icon;
                painter.setIntrinsicWidth(width);
                painter.setIntrinsicHeight(height);
            } else if (icon instanceof BitmapDrawable) {
                // Ensure the bitmap has a density.
                BitmapDrawable bitmapDrawable = (BitmapDrawable) icon;
                Bitmap bitmap = bitmapDrawable.getBitmap();
                if (bitmap.getDensity() == Bitmap.DENSITY_NONE) {
                    bitmapDrawable.setTargetDensity(context.getResources().getDisplayMetrics());
                }
            }
            int sourceWidth = icon.getIntrinsicWidth();
            int sourceHeight = icon.getIntrinsicHeight();
            if (sourceWidth > 0 && sourceHeight > 0) {
                // Scale the icon proportionally to the icon dimensions
                final float ratio = (float) sourceWidth / sourceHeight;
                if (sourceWidth > sourceHeight) {
                    height = (int) (width / ratio);
                } else if (sourceHeight > sourceWidth) {
                    width = (int) (height * ratio);
                }
            }

            // no intrinsic size --> use default size
            int textureWidth = iconBitmapSize;
            int textureHeight = iconBitmapSize;

            final Bitmap bitmap = Bitmap.createBitmap(textureWidth, textureHeight,
                    Bitmap.Config.ARGB_8888);
            final Canvas canvas = sCanvas;
            canvas.setBitmap(bitmap);

            final int left = (textureWidth-width) / 2;
            final int top = (textureHeight-height) / 2;

            @SuppressWarnings("all") // suppress dead code warning
            final boolean debug = false;
            if (debug) {
                // draw a big box for the icon for debugging
                canvas.drawColor(sColors[sColorIndex]);
                if (++sColorIndex >= sColors.length) sColorIndex = 0;
                Paint debugPaint = new Paint();
                debugPaint.setColor(0xffcccc00);
                canvas.drawRect(left, top, left+width, top+height, debugPaint);
            }

            sOldBounds.set(icon.getBounds());
            icon.setBounds(left, top, left+width, top+height);
            icon.draw(canvas);
            icon.setBounds(sOldBounds);
            canvas.setBitmap(null);

            return  bitmap;
        }
    }

修改方法是，给他返回的bitmap添加相应的边框 ，把最末尾的：  

return  bitmap;

改为 ：

return addBorderToImage(bitmap, iconBitmapSize);

关键地方就是这个  addBorderToImage 的实现：

private static float mRoundedRate = 7f;  //圆角的角度
	
    private static Bitmap addBorderToImage(Bitmap src, int iconSize) {

		int width = iconSize;//getBorderWidth();
		int height = iconSize;//getBorderHeight();
		
		Bitmap output = Bitmap.createBitmap(width, height,
				Bitmap.Config.ARGB_8888);
		
		Canvas canvas = new Canvas(output);
		
		
		
		RectF outerRect = new RectF(0,0,width,height);
		
		Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG);
		
		LinearGradient mLinearGradientClamp = new LinearGradient(0, 0, 0, height, new int[] {getCenterTopColor(src),getCenterBottomColor(src)}, null, TileMode.CLAMP);
		
		
		paint.setShader(mLinearGradientClamp);
		
		canvas.drawRoundRect(outerRect, width/mRoundedRate, height/mRoundedRate, paint);
		
		paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_ATOP));
		int sw = src.getWidth();
		int sh = src.getHeight();
		
		Rect srcRect = new Rect(0,0,sw,sh);
		Rect dstRect = getDstRect(sw,sh,width,height);
		
		canvas.drawBitmap(src, srcRect, dstRect, paint);
		
		
		return output;
	}
    
	private static Rect getDstRect( int sw,int sh,int w,int h){
		return new Rect(0,0,w,h);
	}
    
    /**
	 * 得到原始图片中，底部中间的第一个完全不透明的颜色
	 * @return
	 */
	private static int getCenterTopColor(Bitmap src){
		int w = src.getWidth();
		int h = src.getHeight();
		
		int x = (int) (w*0.5);
		
		int c = Color.WHITE;
		for(int y =h-1;y>=0;--y){
			int pixel = src.getPixel(x, y);
			if(Color.alpha(pixel)==0xFF){
				c = pixel;
			}
		}
		return softColor(c);
	}
/**
* 得到原始图片中，顶部中间的第一个完全不透明的颜色
 * @return
 */
	private static int getCenterBottomColor(Bitmap src){
		int w = src.getWidth();
		int h = src.getHeight();
		
		int x = (int) (w*0.5);
		
		int c = Color.WHITE;
		for(int y =0;y<h;++y){
			int pixel = src.getPixel(x, y);
			if(Color.alpha(pixel)==0xFF){
				c = pixel;
			}
		}
		
		return softColor(c);
	}
	
/**
* 将颜色变浅，变淡
* @param color
* @return
*/
	private static int softColor(int color){
		int r = (int) (Color.red(color)*1.3);
		int b = (int) (Color.blue(color)*1.3);
		int g = (int) (Color.green(color)*1.3);
		int af = 0xFF;
		
		if(b >= 0xFF){
			b = 0xFF;
		}
		if(r>=0xFF){
			r = 0xFF;
		}
		if(g>=0xFF){
			g = 0xFF;
		}
		
		return af<<24|r<<16|g<<8|b;
	}