From 919dd0200074cbaac655ee2cb3f8767592f80514 Mon Sep 17 00:00:00 2001
From: David Robillard <d@drobilla.net>
Date: Sat, 14 Mar 2020 17:14:00 +0100
Subject: Windows: Use ephemeral Cairo surface for drawing

---
 pugl/detail/win_cairo.c | 75 ++++++++++++++++++++++++-------------------------
 1 file changed, 37 insertions(+), 38 deletions(-)

diff --git a/pugl/detail/win_cairo.c b/pugl/detail/win_cairo.c
index be0e1d1..4e37f0f 100644
--- a/pugl/detail/win_cairo.c
+++ b/pugl/detail/win_cairo.c
@@ -1,5 +1,5 @@
 /*
-  Copyright 2012-2019 David Robillard <http://drobilla.net>
+  Copyright 2012-2020 David Robillard <http://drobilla.net>
 
   Permission to use, copy, modify, and/or distribute this software for any
   purpose with or without fee is hereby granted, provided that the above
@@ -21,6 +21,7 @@
 #include "pugl/detail/types.h"
 #include "pugl/detail/win.h"
 #include "pugl/pugl_cairo.h"
+#include "pugl/pugl_stub.h"
 
 #include <cairo-win32.h>
 #include <cairo.h>
@@ -46,15 +47,6 @@ puglWinCairoCreateDrawContext(PuglView* view)
 
 	DeleteObject(SelectObject(surface->drawDc, surface->drawBitmap));
 
-	cairo_status_t st = CAIRO_STATUS_SUCCESS;
-	if (!(surface->surface = cairo_win32_surface_create(surface->drawDc)) ||
-	    (st = cairo_surface_status(surface->surface)) ||
-	    !(surface->cr = cairo_create(surface->surface)) ||
-	    (st = cairo_status(surface->cr))) {
-		return PUGL_CREATE_CONTEXT_FAILED;
-	}
-
-	cairo_save(surface->cr);
 	return PUGL_SUCCESS;
 }
 
@@ -66,11 +58,7 @@ puglWinCairoDestroyDrawContext(PuglView* view)
 
 	DeleteDC(surface->drawDc);
 	DeleteObject(surface->drawBitmap);
-	cairo_destroy(surface->cr);
-	cairo_surface_destroy(surface->surface);
 
-	surface->surface    = NULL;
-	surface->cr         = NULL;
 	surface->drawDc     = NULL;
 	surface->drawBitmap = NULL;
 
@@ -90,10 +78,32 @@ puglWinCairoConfigure(PuglView* view)
 	return st;
 }
 
+static void
+puglWinCairoClose(PuglView* view)
+{
+	PuglInternals* const       impl    = view->impl;
+	PuglWinCairoSurface* const surface = (PuglWinCairoSurface*)impl->surface;
+
+	cairo_surface_destroy(surface->surface);
+
+	surface->surface = NULL;
+}
+
 static PuglStatus
-puglWinCairoCreate(PuglView* view)
+puglWinCairoOpen(PuglView* view)
 {
-	return puglWinCairoCreateDrawContext(view);
+	PuglInternals* const       impl    = view->impl;
+	PuglWinCairoSurface* const surface = (PuglWinCairoSurface*)impl->surface;
+
+	cairo_status_t st = CAIRO_STATUS_SUCCESS;
+	if (!(surface->surface = cairo_win32_surface_create(surface->drawDc)) ||
+	    (st = cairo_surface_status(surface->surface)) ||
+	    !(surface->cr = cairo_create(surface->surface)) ||
+	    (st = cairo_status(surface->cr))) {
+		return PUGL_CREATE_CONTEXT_FAILED;
+	}
+
+	return PUGL_SUCCESS;
 }
 
 static PuglStatus
@@ -102,6 +112,7 @@ puglWinCairoDestroy(PuglView* view)
 	PuglInternals* const       impl    = view->impl;
 	PuglWinCairoSurface* const surface = (PuglWinCairoSurface*)impl->surface;
 
+	puglWinCairoClose(view);
 	puglWinCairoDestroyDrawContext(view);
 	free(surface);
 	impl->surface = NULL;
@@ -112,16 +123,16 @@ puglWinCairoDestroy(PuglView* view)
 static PuglStatus
 puglWinCairoEnter(PuglView* view, const PuglEventExpose* expose)
 {
-	PuglInternals* const       impl    = view->impl;
-	PuglWinCairoSurface* const surface = (PuglWinCairoSurface*)impl->surface;
+	PuglStatus st = PUGL_SUCCESS;
 
-	if (expose) {
+	if (expose &&
+	    !(st = puglWinCairoCreateDrawContext(view)) &&
+	    !(st = puglWinCairoOpen(view))) {
 		PAINTSTRUCT ps;
 		BeginPaint(view->impl->hwnd, &ps);
-		cairo_save(surface->cr);
 	}
 
-	return PUGL_SUCCESS;
+	return st;
 }
 
 static PuglStatus
@@ -131,12 +142,14 @@ puglWinCairoLeave(PuglView* view, const PuglEventExpose* expose)
 	PuglWinCairoSurface* const surface = (PuglWinCairoSurface*)impl->surface;
 
 	if (expose) {
-		cairo_restore(surface->cr);
 		cairo_surface_flush(surface->surface);
 		BitBlt(impl->hdc,
 		       0, 0, (int)view->frame.width, (int)view->frame.height,
 		       surface->drawDc, 0, 0, SRCCOPY);
 
+		puglWinCairoClose(view);
+		puglWinCairoDestroyDrawContext(view);
+
 		PAINTSTRUCT ps;
 		EndPaint(view->impl->hwnd, &ps);
 		SwapBuffers(view->impl->hdc);
@@ -145,20 +158,6 @@ puglWinCairoLeave(PuglView* view, const PuglEventExpose* expose)
 	return PUGL_SUCCESS;
 }
 
-static PuglStatus
-puglWinCairoResize(PuglView* view,
-                   int       PUGL_UNUSED(width),
-                   int       PUGL_UNUSED(height))
-{
-	PuglStatus st = PUGL_SUCCESS;
-	if ((st = puglWinCairoDestroyDrawContext(view)) ||
-	    (st = puglWinCairoCreateDrawContext(view))) {
-		return st;
-	}
-
-	return PUGL_SUCCESS;
-}
-
 static void*
 puglWinCairoGetContext(PuglView* view)
 {
@@ -169,11 +168,11 @@ const PuglBackend*
 puglCairoBackend()
 {
 	static const PuglBackend backend = {puglWinCairoConfigure,
-	                                    puglWinCairoCreate,
+	                                    puglStubCreate,
 	                                    puglWinCairoDestroy,
 	                                    puglWinCairoEnter,
 	                                    puglWinCairoLeave,
-	                                    puglWinCairoResize,
+	                                    puglStubResize,
 	                                    puglWinCairoGetContext};
 
 	return &backend;
-- 
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