Clojure/Swing/Java 中 BufferedImage 和 ImageObserver 的问题

Question

我已经尝试了好几个小时，通过绘制存储在 Clojure ref 中的 BufferedImage 来让我的绘图方法正常工作，然后按顺序将其绘制到组件上（在本例中为 JPanel）显示它。不幸的是，这根本无法正常工作。

我的代码是这样的（精简了，但显示了相关部分：

(defn create-graph
  "Data-ref is [xs ys], buffered-image-ref holds the basic graph."
  [data-ref buffered-image-ref & {:keys [width height image]}]
  (proxy [JPanel]
      []
    (getPreferredSize [] (Dimension. width  height))
    (paintComponent [g]
                    (proxy-super paintComponent g)
                    (if-not @buffered-image-ref
                      (dosync
                       (ref-set buffered-image-ref
                                (xy-plot2
                                 (first @data-ref)
                                 (second @data-ref)
                                 (.getGraphics
                                  (BufferedImage. width height 
                                                  BufferedImage/TYPE_INT_ARGB))
                                 :axis? true
                                 :width width
                                 :height height))))
                    (.drawImage g @buffered-image-ref
                                0 0 
                                (proxy [ImageObserver]
                                         []
                                       (imageUpdate []
                                          (proxy-super imageUpdate)))))))

下面是 xy-plot2（这似乎不是问题，但为了完整起见，我将其包括在内：

(defn xy-plot2
  "Draws an xy-plot in the given Graphics context.
   'xs must be equal in length to 'ys."
  [xs ys gfx
   & {:keys [color max-y axis? y-buffer width height]
     :or {color Color/RED y-buffer 0}}]
  (let [h (/ height 2) ;; since we have -h to h (not 0 to h)
        w width ;; since we graph 0 to w
        len (count xs)
        min-x (apply min xs)
        xs (if-not (zero? min-x)
             (map #(- % min-x) xs)
             xs)
        max-y (or max-y (apply max ys))
        max-x (apply max xs)]
    (.setColor gfx color)
    (dorun ;; this is the key part, along with scale-xs and draw-l
     (take len
           (iterate (partial d-line gfx h)
                    [(scale-xs xs w 0)
                     (scale-xs ys h y-buffer)])))
    (and axis? (or (.setColor gfx Color/BLACK) (.drawLine gfx 0 h w h)))
    gfx))

当我运行它时，我得到了这个错误，这导致我相信我在 paintComponent() 方法的最后部分搞砸了。

Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException:
No matching method found: drawImage for class sun.java2d.SunGraphics2D

我尝试将nil 替换为ImageObserver，但无济于事。我尝试了其他 arg 命令（对于其他类型的 Graphics 类的其他 drawImage 方法）。一切都无济于事。

对不起，如果我听起来有点难以理解，这个错误一直困扰着我。如果需要，我会在早上编辑！

非常感谢，非常感谢， 艾萨克

Answer 1

看起来 buffered-image-ref 设置为 BufferedImage 的图形，而不是图像本身。