1 files changed, 73 insertions, 0 deletions
diff --git a/areahandler.go b/areahandler.go
new file mode 100644
index 0000000..0998f56
--- /dev/null
+++ b/areahandler.go
@@ -0,0 +1,73 @@
+// 13 december 2015
+package main
+
+// #include "ui.h"
+// extern void doAreaHandlerDraw(uiAreaHandler *, uiArea *, uiAreaDrawParams *);
+// static inline void uiAreaHandler *allocAreaHandler(void)
+// {
+// 	uiAreaHandler *ah;
+// 
+// 	ah = (uiAreaHandler *) malloc(sizeof (uiAreaHandler));
+// 	if (ah == NULL)
+// 		return NULL;
+// 	ah->Draw = doAreaHandlerDraw;
+// 	return ah;
+// }
+// static inline void freeAreaHandler(uiAreaHandler *ah)
+// {
+// 	free(ah);
+// }
+import "C"
+
+// no need to lock this; only the GUI thread can access it
+var areahandlers = make(map[*C.uiAreaHandler]AreaHandler)
+
+// AreaHandler defines the functionality needed for handling events
+// from an Area.
+type AreaHandler interface {
+	// TODO document all these
+	Draw(a *Area, dp *AreaDrawParams)
+}
+
+func registerHandler(ah AreaHandler) *C.uiAreaHandler {
+	uah := C.allocAreaHandler()
+	areahandlers[uah] = ah
+	return uah
+}
+
+func unregisterAreaHandler(uah *C.uiAreaHandler) {
+	delete(areahandlers, uah)
+	C.freeAreaHandler(uah)
+}
+
+// AreaDrawParams defines the TODO.
+type AreaDrawParams struct {
+	// TODO document all these
+	Context		*DrawContext
+	ClientWidth	float64
+	ClientHeight	float64
+	ClipX		float64
+	ClipY		float64
+	ClipWidth		float64
+	ClipHeight	float64
+	HScrollPos	int
+	VScrollPos	int
+}
+
+// export doAreaHandlerDraw
+func doAreaHandlerDraw(uah *C.uiAreaHandler, ua *C.uiArea, udp *C.uiAreaDrawParams) {
+	ah := areahandlers[uah]
+	a := areas[ua]
+	dp := &AreaDrawParams{
+		Context:		&DrawContext{udp.Context},
+		ClientWidth:	float64(udp.ClientWidth),
+		ClientHeight:	float64(udp.ClientHeight),
+		ClipX:		float64(udp.ClipX),
+		ClipY:		float64(udp.ClipY),
+		ClipWidth:		float64(udp.ClipWidth),
+		ClipHeight:	float64(udp.ClipHeight),
+		HScrollPos:	int(udp.HScrollPos),
+		VScrollPos:	int(udp.VScrollPos),
+	}
+	ah.Draw(a, dp)
+}