feat: add canvas prototype

src/ui/vektorcanvas.h

@@ -0,0 +1,31 @@
+#ifndef VKTR_CANVAS_H
+#define VKTR_CANVAS_H
+
+#include "uicontroller.h"
+
+typedef struct VektorCanvas {
+    GtkPicture* canvasWidget;
+
+    // texture related stuff
+    guchar* canvasPixels;
+    GdkTexture* canvasTexture;
+    GBytes* canvasPixelBytes;
+
+    int width;
+    int height;
+} VektorCanvas;
+
+typedef struct VektorCanvasColor {
+    guchar r;
+    guchar g;
+    guchar b;
+    guchar a;
+} VektorCanvasColor;
+
+void vektor_canvas_init(VektorWidgetState* state, VektorCanvas* canvasOut);
+void vektor_canvas_update(VektorCanvas* canvas);
+void vektor_canvas_fill(VektorCanvas* canvas, VektorCanvasColor* color);
+
+VektorCanvasColor vektor_color_new(guchar r, guchar g, guchar b, guchar a);
+
+#endif