android custom charts

effect of these two charts , seeking advice how to achieve great God , especially the first one , so hard ! ! !
------ Solution ---------------------------------------- ----
rewrite onDraw method
which calls
RadialGradient class try
I just did a straight line , did not make this round

  @Override
  	protected void onDraw(Canvas canvas) {
  		super.onDraw(canvas);
  		mRect = new Rect();  
  		mRect.set(0, 0, showwidth, height); 
  		Paint p=new Paint();
  		
  		int color1 = Color.parseColor("#f1c40f");
  		int color2 = Color.parseColor("#f39c12");
  //		int rgb1 = Color.rgb(1, 1, 1);
  //		int rgb2 = Color.rgb(1, 1, 1);
  //		LinearGradient lg=new LinearGradient(0,0,screenWidth,0,color1,color2,TileMode.CLAMP);  //
  		RadialGradient rg=new RadialGradient(x, y, radius, color0, color1, tile);
  		p.setShader(rg);
  		canvas.drawRect(mRect, p);  
  	}
  

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amount , draw a piece of fan- out, but how the mess needs to be studied figure !!!!!
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that I have to learn
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amount , draw a piece of fan- out, but how the mess needs to be studied figure ! ! ! ! !  
you can think about, which is drawn out of a fan ,
then I can put a figure to cut into this sector .
So if in the middle of this picture is the transparent color , then,
renderings that is wanted.
Of course , this is just my idea, I do not know how they are doing.
------ eference --------------------------------------- < br>
    
amount , draw a piece of fan- out, but how the mess needs to be studied figure ! ! ! ! !          
you can think about, which is drawn out of a fan ,   
then I can put a figure to cut into this sector .   
So if in the middle of this picture is the transparent color , then,   
renderings that is wanted.   
Of course , this is just my idea, I do not know how they are doing.  
hey , study it slowly ! ! ! ! ! !
Thank you !