ST_ClipEx a working variation of ST_Clip for raster

ST_ClipEx.sql

CREATE OR REPLACE FUNCTION ST_ClipEx(rast raster, x int, y int, width int, height int) 
	    RETURNS raster AS  
	    $$ 
	    DECLARE 
	        newrast raster := ST_MakeEmptyRaster(width, height, ST_UpperLeftX(rast), ST_UpperLeftY(rast), 
	                          ST_ScaleX(rast), ST_ScaleY(rast), ST_SkewX(rast), ST_SkewY(rast), ST_SRID(rast)); 
	        numband int := ST_Numbands(rast); 
	        band int; 
	        cx int; 
	        cy int; 
	        newwidth int := CASE WHEN x + width > ST_Width(rast) THEN ST_Width(rast) - x ELSE width END; 
	        newheight int := CASE WHEN y + height > ST_Height(rast) THEN ST_Height(rast) - y ELSE height END; 
	    BEGIN 
	       
	        FOR band IN 1..numband LOOP 
	                newrast := ST_AddBand(newrast, '8BUI'::text, 0, 0); 
	                FOR cx IN 1..newwidth LOOP 
	                        FOR cy IN 1..newheight LOOP 
	                                newrast := ST_SetValue(newrast, band, cx, cy, ST_Value(rast, band, cx + x - 1, cy + y - 1)); 
	                        END LOOP; 
	                END LOOP; 
	        END LOOP; 
	        RETURN newrast; 
	    END; 
	    $$ 
	    LANGUAGE 'plpgsql';