app: [API] make ViewEvent an interface on all platforms

A uniform type allows convenient nil checks and for future window
backends on platforms other than Linux (which already had ViewEvent
as an interface).

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/app.go

@@ -56,6 +56,13 @@ type FrameEvent struct {
 	Source input.Source
 }
 
+// ViewEvent provides handles to the underlying window objects for the
+// current display protocol.
+type ViewEvent interface {
+	implementsViewEvent()
+	ImplementsEvent()
+}
+
 // Insets is the space taken up by
 // system decoration such as translucent
 // system bars and software keyboards.

app/os_android.go

@@ -205,9 +205,9 @@ type pixelInsets struct {
 	top, bottom, left, right int
 }
 
-// ViewEvent is sent whenever the Window's underlying Android view
+// AndroidViewEvent is sent whenever the Window's underlying Android view
 // changes.
-type ViewEvent struct {
+type AndroidViewEvent struct {
 	// View is a JNI global reference to the android.view.View
 	// instance backing the Window. The reference is valid until
 	// the next ViewEvent is received.
@@ -514,7 +514,7 @@ func Java_org_gioui_GioView_onCreateView(env *C.JNIEnv, class C.jclass, view C.j
 	w.setConfig(env, cnf)
 	w.SetInputHint(w.inputHint)
 	w.setStage(StagePaused)
-	w.processEvent(ViewEvent{View: uintptr(view)})
+	w.processEvent(AndroidViewEvent{View: uintptr(view)})
 	return C.jlong(w.handle)
 }
 
@@ -805,7 +805,7 @@ func (w *window) semIDFor(virtID C.jint) input.SemanticID {
 
 func (w *window) detach(env *C.JNIEnv) {
 	callVoidMethod(env, w.view, gioView.unregister)
-	w.processEvent(ViewEvent{})
+	w.processEvent(AndroidViewEvent{})
 	w.handle.Delete()
 	C.jni_DeleteGlobalRef(env, w.view)
 	w.view = 0
@@ -1504,4 +1504,5 @@ func Java_org_gioui_Gio_scheduleMainFuncs(env *C.JNIEnv, cls C.jclass) {
 	}
 }
 
-func (_ ViewEvent) ImplementsEvent() {}
+func (AndroidViewEvent) implementsViewEvent() {}
+func (AndroidViewEvent) ImplementsEvent()     {}

app/os_ios.go

@@ -93,7 +93,7 @@ import (
 	"gioui.org/unit"
 )
 
-type ViewEvent struct {
+type UIKitViewEvent struct {
 	// ViewController is a CFTypeRef for the UIViewController backing a Window.
 	ViewController uintptr
 }
@@ -139,7 +139,7 @@ func onCreate(view, controller C.CFTypeRef) {
 	C.gio_viewSetHandle(view, C.uintptr_t(cgo.NewHandle(w)))
 	w.Configure(wopts.options)
 	w.ProcessEvent(StageEvent{Stage: StageRunning})
-	w.ProcessEvent(ViewEvent{ViewController: uintptr(controller)})
+	w.ProcessEvent(UIKitViewEvent{ViewController: uintptr(controller)})
 }
 
 func viewFor(h C.uintptr_t) *window {
@@ -203,7 +203,7 @@ func onStart(h C.uintptr_t) {
 //export onDestroy
 func onDestroy(h C.uintptr_t) {
 	w := viewFor(h)
-	w.ProcessEvent(ViewEvent{})
+	w.ProcessEvent(UIKitViewEvent{})
 	w.ProcessEvent(DestroyEvent{})
 	w.displayLink.Close()
 	w.displayLink = nil
@@ -398,4 +398,5 @@ func gio_runMain() {
 	runMain()
 }
 
-func (_ ViewEvent) ImplementsEvent() {}
+func (UIKitViewEvent) implementsViewEvent() {}
+func (UIKitViewEvent) ImplementsEvent()     {}

app/os_js.go

@@ -25,7 +25,7 @@ import (
 	"gioui.org/unit"
 )
 
-type ViewEvent struct {
+type JSViewEvent struct {
 	Element js.Value
 }
 
@@ -114,7 +114,7 @@ func newWindow(win *callbacks, options []Option) {
 
 	w.Configure(options)
 	w.blur()
-	w.processEvent(ViewEvent{Element: cont})
+	w.processEvent(JSViewEvent{Element: cont})
 	w.processEvent(StageEvent{Stage: StageRunning})
 	w.resize()
 	w.draw(true)
@@ -830,4 +830,5 @@ func translateKey(k string) (key.Name, bool) {
 	return n, true
 }
 
-func (_ ViewEvent) ImplementsEvent() {}
+func (JSViewEvent) implementsViewEvent() {}
+func (JSViewEvent) ImplementsEvent()     {}

app/os_macos.go

@@ -297,9 +297,9 @@ func init() {
 	runtime.LockOSThread()
 }
 
-// ViewEvent notifies the client of changes to the window AppKit handles.
-// The handles are retained until another ViewEvent is sent.
-type ViewEvent struct {
+// AppKitViewEvent notifies the client of changes to the window AppKit handles.
+// The handles are retained until another AppKitViewEvent is sent.
+type AppKitViewEvent struct {
 	// View is a CFTypeRef for the NSView for the window.
 	View uintptr
 	// Layer is a CFTypeRef of the CALayer of View.
@@ -862,9 +862,9 @@ func gio_onAttached(h C.uintptr_t, attached C.int) {
 	w := windowFor(h)
 	if attached != 0 {
 		layer := C.layerForView(w.view)
-		w.ProcessEvent(ViewEvent{View: uintptr(w.view), Layer: uintptr(layer)})
+		w.ProcessEvent(AppKitViewEvent{View: uintptr(w.view), Layer: uintptr(layer)})
 	} else {
-		w.ProcessEvent(ViewEvent{})
+		w.ProcessEvent(AppKitViewEvent{})
 		w.setStage(StagePaused)
 	}
 }
@@ -1057,4 +1057,5 @@ func convertMods(mods C.NSUInteger) key.Modifiers {
 	return kmods
 }
 
-func (_ ViewEvent) ImplementsEvent() {}
+func (AppKitViewEvent) implementsViewEvent() {}
+func (AppKitViewEvent) ImplementsEvent()     {}

app/os_unix.go

@@ -13,13 +13,6 @@ import (
 	"gioui.org/io/pointer"
 )
 
-// ViewEvent provides handles to the underlying window objects for the
-// current display protocol.
-type ViewEvent interface {
-	implementsViewEvent()
-	ImplementsEvent()
-}
-
 type X11ViewEvent struct {
 	// Display is a pointer to the X11 Display created by XOpenDisplay.
 	Display unsafe.Pointer

app/os_windows.go

@@ -31,7 +31,7 @@ import (
 	"gioui.org/io/transfer"
 )
 
-type ViewEvent struct {
+type Win32ViewEvent struct {
 	HWND uintptr
 }
 
@@ -113,7 +113,7 @@ func newWindow(win *callbacks, options []Option) {
 		}
 		winMap.Store(w.hwnd, w)
 		defer winMap.Delete(w.hwnd)
-		w.ProcessEvent(ViewEvent{HWND: uintptr(w.hwnd)})
+		w.ProcessEvent(Win32ViewEvent{HWND: uintptr(w.hwnd)})
 		w.Configure(options)
 		windows.SetForegroundWindow(w.hwnd)
 		windows.SetFocus(w.hwnd)
@@ -308,7 +308,7 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 	case windows.WM_MOUSEHWHEEL:
 		w.scrollEvent(wParam, lParam, true, getModifiers())
 	case windows.WM_DESTROY:
-		w.ProcessEvent(ViewEvent{})
+		w.ProcessEvent(Win32ViewEvent{})
 		w.ProcessEvent(DestroyEvent{})
 		if w.hdc != 0 {
 			windows.ReleaseDC(w.hdc)
@@ -1011,4 +1011,5 @@ func configForDPI(dpi int) unit.Metric {
 	}
 }
 
-func (_ ViewEvent) ImplementsEvent() {}
+func (Win32ViewEvent) implementsViewEvent() {}
+func (Win32ViewEvent) ImplementsEvent()     {}