[#15] Couple of image functions and fix bug with bgcolor option

docs/quil.core.md

@@ -17,7 +17,7 @@
 - [x] [`atan2`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L423) - "Calculates the angle (in radians) from a specified point to the  coordinate origin as measured from the positive x-axis"
 - [ ] [`available-fonts`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L441) - "A sequence of strings representing the fonts on this system  available for use"
 - [x] [`background`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L462) - "Sets the color used for the background of the Processing  window"
-- [ ] [`background-image`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L482) - "Specify an image to be used as the background for a sketch"
+- [x] [`background-image`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L482) - "Specify an image to be used as the background for a sketch"
 - [ ] [`begin-camera`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L495) - "Sets the matrix mode to the camera matrix so calls such as  translate, rotate, apply-matrix and reset-matrix affect the  camera"
 - [ ] [`begin-contour`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L512) - "Use the begin-contour and end-contour function to create negative  shapes within shapes"
 - [ ] [`begin-raw`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L527) - "Enables the creation of vectors from 3D data"
@@ -28,7 +28,7 @@
 - [ ] [`bezier-tangent`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L632) - "Calculates the tangent of a point on a Bezier curve"
 - [ ] [`bezier-vertex`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L645) - "Specifies vertex coordinates for Bezier curves"
 - [ ] [`binary`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L671) - "Returns a string representing the binary value of an int, char or  byte"
-- [ ] [`blend`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L688) - "Blends a region of pixels from one image into another with full alpha  channel support"
+- [ ] [`blend`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L688) - "Blends a region of pixels from one image into another with full alpha channel support"
 - [ ] [`blend-color`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L737) - "Blends two color values together based on the blending mode given specified  with the mode keyword"
 - [ ] [`blend-mode`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L781) - "Blends the pixels in the display window according to the defined mode"
 - [ ] [`blend-modes`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L51)
@@ -46,7 +46,7 @@
 - [x] [`cos`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L1021) - "Calculates the cosine of an angle"
 - [ ] [`create-font`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L1050) - "Dynamically converts a font to the format used by Processing (a  PFont) from either a font name that's installed on the computer, or  from a "
 - [ ] [`create-graphics`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L1087) - "Creates and returns a new PGraphics object of the types :p2d, :p3d,  :java2d, :pdf"
-- [ ] [`create-image`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L1126) - "Creates a new PImage (the datatype for storing images)"
+- [x] [`create-image`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L1126) - "Creates a new PImage (the datatype for storing images)"
 - [x] [`current-fill`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L1147) - "Return the current fill color"
 - [x] [`current-frame-rate`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L1693) - "Returns the current framerate"
 - [ ] [`current-graphics`](https://github.com/quil/quil/blob/2.8.0/src/cljc/quil/core.cljc#L32) - "Graphics currently used for drawing"

src/doodler/core.clje

@@ -208,6 +208,16 @@
   (let* [#erl[_ _ _ min max _] (hsb-helper color)]
     (/ (+ min max) 2)))
 
+;; Image
+
+(defn background-image
+  [img]
+  (wxDC/drawBitmap *canvas* img #erl[0 0]))
+
+(defn create-image
+  [w h]
+  (wxBitmap/new w h))
+
 ;; Stroke & fill
 
 (defn- save-current-stroke
@@ -315,10 +325,14 @@
   ([x y w h r]
    (wxDC/drawRoundedRectangle *canvas* #erl[x y] #erl[w h] r)))
 
+;; Text
+
 (defn text
   [s x y]
   (wxDC/drawText *canvas* s #erl[x y]))
 
+;; Dimension
+
 (defn width
   []
   (:width *sketch*))

src/doodler/sketch.clje

@@ -123,7 +123,8 @@
                                     features)
         canvas      (gui/make-canvas frame)
 
-        bgcolor     (apply core/color (:bgcolor opts))
+        bgcolor     (when-let [bgcolor (:bgcolor opts)]
+                      (apply core/color bgcolor))
 
         draw-fn     (or (:draw opts) u/no-fn)
         setup-fn    (or (:setup opts) u/no-fn)
@@ -147,7 +148,8 @@
       (e/listen canvas event-name))
 
     ;; Set background color before showing the frame
-    (wxWindow/setBackgroundColour canvas bgcolor)
+    (when bgcolor
+      (wxWindow/setBackgroundColour canvas bgcolor))
 
     ;; Show frame, maybe in fullscreen
     (wxFrame/showFullScreen frame (:present features))