tikz 绘图的代码和效果_tikz, 斜渐变色

\begin{frame}
  \frametitle{tikzpicture}
  \AppendLogo

    \begin{tikzpicture}[label distance = 2mm]

    \draw[->] (-1,0) -- (5,0) node[below,circle,draw,label distance = 1cm,label=right:This is x] {x};
    \draw[->] (0,-1) -- (0,4) node[left,rectangle,draw] {y};
    \draw[color = green,line width = 3mm] (0,0) -- plot coordinates {(1,0)  (1,1)  (0,1)} -- cycle;
    \draw[color = black,thick,rotate = 45] (3,3) circle (1cm and 2cm);
    \draw[step=0.25cm,color = blue] (1,1) grid (3,3);
    \tikzstyle{my style}=[yellow,dashed,thick];
    \draw[style = my style] (2,0) parabola (3,3);
    \draw[style = my style] (1,0) arc (0:90:1cm);

    \begin{scope}[dashed]
    \draw (2,2) circle (2cm);
    \draw (2,2) circle (1.5cm);
    \draw (2,2) circle (1cm);
    \draw (2,2) circle (0.5cm);
    \end{scope}
    \draw (5,4) node [circle,fill=gray!20,label = right:3,label=above:12,label=below:6,lab