win32: don't use CS_OWNDC

CS_OWNDC will make GetDC() always return the same HDC. This might
become a problem when OpenGL rendering and window management are
on different threads. Although I'm not too sure about this; our
code never requests a HDC outside of the OpenGL backend, and it
depends on whether win32 will internally request DCs. But in any
case, this seems to be cleaner.

Move the GL pixelformat setup code to gl_w32.c, where it's actually
needed. This also fixes that SetPixelFormat() should be called only
once, and not every time video params change.

2 files changed, 64 insertions, 46 deletions

diff --git a/video/out/gl_w32.c b/video/out/gl_w32.c
index 4433875cbf..9d704bcca6 100644
--- a/video/out/gl_w32.c
+++ b/video/out/gl_w32.c
@@ -19,14 +19,60 @@
  * version 2.1 of the License, or (at your option) any later version.
  */
 
+#include <assert.h>
 #include <windows.h>
 #include "w32_common.h"
 #include "gl_common.h"
 
 struct w32_context {
     HGLRC context;
+    HDC hdc;
 };
 
+static bool create_dc(struct MPGLContext *ctx, int flags)
+{
+    struct w32_context *w32_ctx = ctx->priv;
+    HWND win = vo_w32_hwnd(ctx->vo);
+
+    assert(!w32_ctx->hdc);
+
+    HDC hdc = GetDC(win);
+    if (!hdc)
+        return false;
+
+    PIXELFORMATDESCRIPTOR pfd;
+    memset(&pfd, 0, sizeof pfd);
+    pfd.nSize = sizeof pfd;
+    pfd.nVersion = 1;
+    pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;
+
+    if (flags & VOFLAG_STEREO)
+        pfd.dwFlags |= PFD_STEREO;
+
+    pfd.iPixelType = PFD_TYPE_RGBA;
+    pfd.cColorBits = 24;
+    pfd.iLayerType = PFD_MAIN_PLANE;
+    int pf = ChoosePixelFormat(hdc, &pfd);
+
+    if (!pf) {
+        MP_ERR(ctx->vo, "unable to select a valid pixel format!\n");
+        ReleaseDC(win, hdc);
+        return false;
+    }
+
+    SetPixelFormat(hdc, pf, &pfd);
+
+    int pfmt = GetPixelFormat(hdc);
+    if (DescribePixelFormat(hdc, pfmt, sizeof(PIXELFORMATDESCRIPTOR), &pfd)) {
+        ctx->depth_r = pfd.cRedBits;
+        ctx->depth_g = pfd.cGreenBits;
+        ctx->depth_b = pfd.cBlueBits;
+    }
+
+    w32_ctx->hdc = hdc;
+    return true;
+}
+
 static void *w32gpa(const GLubyte *procName)
 {
     HMODULE oglmod;
@@ -37,7 +83,7 @@ static void *w32gpa(const GLubyte *procName)
     return GetProcAddress(oglmod, procName);
 }
 
-static bool create_context_w32_old(struct MPGLContext *ctx)
+static bool create_context_w32_old(struct MPGLContext *ctx, int flags)
 {
     struct w32_context *w32_ctx = ctx->priv;
     HGLRC *context = &w32_ctx->context;
@@ -45,8 +91,10 @@ static bool create_context_w32_old(struct MPGLContext *ctx)
     if (*context)
         return true;
 
-    HWND win = vo_w32_hwnd(ctx->vo);
-    HDC windc = GetDC(win);
+    if (!create_dc(ctx, flags))
+        return false;
+
+    HDC windc = w32_ctx->hdc;
     bool res = false;
 
     HGLRC new_context = wglCreateContext(windc);
@@ -67,11 +115,10 @@ static bool create_context_w32_old(struct MPGLContext *ctx)
     res = true;
 
 out:
-    ReleaseDC(win, windc);
     return res;
 }
 
-static bool create_context_w32_gl3(struct MPGLContext *ctx)
+static bool create_context_w32_gl3(struct MPGLContext *ctx, int flags)
 {
     struct w32_context *w32_ctx = ctx->priv;
     HGLRC *context = &w32_ctx->context;
@@ -79,8 +126,10 @@ static bool create_context_w32_gl3(struct MPGLContext *ctx)
     if (*context) // reuse existing context
         return true; // not reusing it breaks gl3!
 
-    HWND win = vo_w32_hwnd(ctx->vo);
-    HDC windc = GetDC(win);
+    if (!create_dc(ctx, flags))
+        return false;
+
+    HDC windc = w32_ctx->hdc;
     HGLRC new_context = 0;
 
     new_context = wglCreateContext(windc);
@@ -147,14 +196,6 @@ static bool create_context_w32_gl3(struct MPGLContext *ctx)
     /* update function pointers */
     mpgl_load_functions(ctx->gl, w32gpa, NULL, ctx->vo->log);
 
-    int pfmt = GetPixelFormat(windc);
-    PIXELFORMATDESCRIPTOR pfd;
-    if (DescribePixelFormat(windc, pfmt, sizeof(PIXELFORMATDESCRIPTOR), &pfd)) {
-        ctx->depth_r = pfd.cRedBits;
-        ctx->depth_g = pfd.cGreenBits;
-        ctx->depth_b = pfd.cBlueBits;
-    }
-
     return true;
 
 unsupported:
@@ -171,9 +212,9 @@ static bool config_window_w32(struct MPGLContext *ctx, int flags)
 
     bool success = false;
     if (ctx->requested_gl_version >= MPGL_VER(3, 0))
-        success = create_context_w32_gl3(ctx);
+        success = create_context_w32_gl3(ctx, flags);
     if (!success)
-        success = create_context_w32_old(ctx);
+        success = create_context_w32_old(ctx, flags);
     return success;
 }
 
@@ -186,13 +227,15 @@ static void releaseGlContext_w32(MPGLContext *ctx)
         wglDeleteContext(*context);
     }
     *context = 0;
+    if (w32_ctx->hdc)
+        ReleaseDC(vo_w32_hwnd(ctx->vo), w32_ctx->hdc);
+    w32_ctx->hdc = NULL;
 }
 
 static void swapGlBuffers_w32(MPGLContext *ctx)
 {
-    HDC vo_hdc = GetDC(vo_w32_hwnd(ctx->vo));
-    SwapBuffers(vo_hdc);
-    ReleaseDC(vo_w32_hwnd(ctx->vo), vo_hdc);
+    struct w32_context *w32_ctx = ctx->priv;
+    SwapBuffers(w32_ctx->hdc);
 }
 
 void mpgl_set_backend_w32(MPGLContext *ctx)
diff --git a/video/out/w32_common.c b/video/out/w32_common.c
index 9e72b5e010..486969e223 100644
--- a/video/out/w32_common.c
+++ b/video/out/w32_common.c
@@ -877,31 +877,6 @@ static int reinit_window_state(struct vo_w32_state *w32)
 int vo_w32_config(struct vo *vo, uint32_t flags)
 {
     struct vo_w32_state *w32 = vo->w32;
-    PIXELFORMATDESCRIPTOR pfd;
-    int pf;
-    HDC vo_hdc = GetDC(w32->window);
-
-    memset(&pfd, 0, sizeof pfd);
-    pfd.nSize = sizeof pfd;
-    pfd.nVersion = 1;
-    pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;
-
-    if (flags & VOFLAG_STEREO)
-        pfd.dwFlags |= PFD_STEREO;
-
-    pfd.iPixelType = PFD_TYPE_RGBA;
-    pfd.cColorBits = 24;
-    pfd.iLayerType = PFD_MAIN_PLANE;
-    pf = ChoosePixelFormat(vo_hdc, &pfd);
-
-    if (!pf) {
-        MP_ERR(w32, "unable to select a valid pixel format!\n");
-        ReleaseDC(w32->window, vo_hdc);
-        return 0;
-    }
-
-    SetPixelFormat(vo_hdc, pf, &pfd);
-    ReleaseDC(w32->window, vo_hdc);
 
     // we already have a fully initialized window, so nothing needs to be done
     if (flags & VOFLAG_HIDDEN)
@@ -966,7 +941,7 @@ int vo_w32_init(struct vo *vo)
 
     WNDCLASSEXW wcex = {
         .cbSize = sizeof wcex,
-        .style = CS_OWNDC | CS_HREDRAW | CS_VREDRAW,
+        .style = CS_HREDRAW | CS_VREDRAW,
         .lpfnWndProc = WndProc,
         .hInstance = hInstance,
         .hIcon = LoadIconW(hInstance, L"IDI_ICON1"),