Add option to support alpha for window or not. This is important for nvidia flip

1 files changed, 78 insertions, 5 deletions

diff --git a/src/window/window.c b/src/window/window.c
index eeb2e43..1817a2f 100644
--- a/src/window/window.c
+++ b/src/window/window.c
@@ -5,6 +5,7 @@
 #include <X11/Xutil.h>
 #include <X11/cursorfont.h>
 #include <X11/Xatom.h>
+#include <X11/extensions/Xrender.h>
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
@@ -68,6 +69,9 @@ typedef struct {
     unsigned int prev_keycode_pressed;
     bool key_was_released;
     Colormap color_map;
+    GLXFBConfig *fbconfigs;
+    GLXFBConfig fbconfig;
+    XVisualInfo *visual_info;
     /*
         Used to stack text event on top of key press/release events and other text events.
         For example pressing a key should give the user both key press and text events
@@ -79,7 +83,55 @@ typedef struct {
 
 static void x11_context_deinit(x11_context *self);
 
-static int x11_context_init(x11_context *self) {
+static bool glx_context_choose(mgl_context *context, GLXFBConfig **fbconfigs, GLXFBConfig *fbconfig, XVisualInfo **visual_info, bool alpha) {
+    const int attr[] = {
+        GLX_RENDER_TYPE, GLX_RGBA_BIT,
+        GLX_DRAWABLE_TYPE, GLX_WINDOW_BIT,
+        GLX_DOUBLEBUFFER, True,
+        GLX_RED_SIZE, 8,
+        GLX_GREEN_SIZE, 8,
+        GLX_BLUE_SIZE, 8,
+        GLX_ALPHA_SIZE, alpha ? 8 : 0,
+        GLX_DEPTH_SIZE, 0,
+        None
+    };
+
+    *fbconfigs = NULL;
+    *visual_info = NULL;
+    *fbconfig = NULL;
+
+    int numfbconfigs = 0;
+    *fbconfigs = context->gl.glXChooseFBConfig(context->connection, DefaultScreen(context->connection), attr, &numfbconfigs);
+    for(int i = 0; i < numfbconfigs; i++) {
+        *visual_info = (XVisualInfo*)context->gl.glXGetVisualFromFBConfig(context->connection, (*fbconfigs)[i]);
+        if(!*visual_info)
+            continue;
+
+        XRenderPictFormat *pict_format = XRenderFindVisualFormat(context->connection, (*visual_info)->visual);
+        if(!pict_format) {
+            XFree(*visual_info);
+            *visual_info = NULL;
+            continue;
+        }
+
+        *fbconfig = (*fbconfigs)[i];
+        if((alpha && pict_format->direct.alphaMask > 0) || (!alpha && pict_format->direct.alphaMask == 0))
+            break;
+
+        XFree(*visual_info);
+        *visual_info = NULL;
+        *fbconfig = NULL;
+    }
+
+    if(!*visual_info) {
+        fprintf(stderr, "mgl error: no appropriate visual found\n");
+        return false;
+    }
+
+    return true;
+}
+
+static int x11_context_init(x11_context *self, bool alpha) {
     mgl_context *context = mgl_get_context();
 
     self->glx_context = NULL;
@@ -101,6 +153,15 @@ static int x11_context_init(x11_context *self) {
     self->key_was_released = false;
     self->color_map = None;
 
+    self->fbconfigs = NULL;
+    self->fbconfig = NULL;
+    self->visual_info = NULL;
+
+    if(!glx_context_choose(context, &self->fbconfigs, &self->fbconfig, &self->visual_info, alpha)) {
+        x11_context_deinit(self);
+        return -1;
+    }
+
     self->default_cursor = XCreateFontCursor(context->connection, XC_arrow);
     if(!self->default_cursor) {
         x11_context_deinit(self);
@@ -157,6 +218,18 @@ void x11_context_deinit(x11_context *self) {
         context->gl.glXDestroyContext(context->connection, self->glx_context);
         self->glx_context = NULL;
     }
+
+    if(self->visual_info) {
+        XFree(self->visual_info);
+        self->visual_info = NULL;
+    }
+
+    if(self->fbconfigs) {
+        XFree(self->fbconfigs);
+        self->fbconfigs = NULL;
+    }
+
+    self->fbconfig = NULL;
 }
 
 static bool x11_context_append_event(x11_context *self, const mgl_event *event) {
@@ -228,7 +301,7 @@ static int mgl_window_init(mgl_window *self, const char *title, const mgl_window
     }
 
     x11_context *x11_context = self->context;
-    if(x11_context_init(x11_context) != 0) {
+    if(x11_context_init(x11_context, params ? params->support_alpha : false) != 0) {
         fprintf(stderr, "mgl error: x11_context_init failed\n");
         mgl_window_deinit(self);
         return -1;
@@ -240,14 +313,14 @@ static int mgl_window_init(mgl_window *self, const char *title, const mgl_window
     if(parent_window == 0)
         parent_window = DefaultRootWindow(context->connection);
 
-    x11_context->glx_context = context->gl.glXCreateNewContext(context->connection, context->fbconfig, GLX_RGBA_TYPE, 0, True);
+    x11_context->glx_context = context->gl.glXCreateNewContext(context->connection, x11_context->fbconfig, GLX_RGBA_TYPE, 0, True);
     if(!x11_context->glx_context) {
         fprintf(stderr, "mgl error: glXCreateContext failed\n");
         mgl_window_deinit(self);
         return -1;
     }
 
-    x11_context->color_map = XCreateColormap(context->connection, DefaultRootWindow(context->connection), ((XVisualInfo*)context->visual_info)->visual, AllocNone);
+    x11_context->color_map = XCreateColormap(context->connection, DefaultRootWindow(context->connection), x11_context->visual_info->visual, AllocNone);
     if(!x11_context->color_map) {
         fprintf(stderr, "mgl error: XCreateColormap failed\n");
         mgl_window_deinit(self);
@@ -280,7 +353,7 @@ static int mgl_window_init(mgl_window *self, const char *title, const mgl_window
     } else {
         self->window = XCreateWindow(context->connection, parent_window, params->position.x, params->position.y,
             window_size.x, window_size.y, 0,
-            ((XVisualInfo*)context->visual_info)->depth, InputOutput, ((XVisualInfo*)context->visual_info)->visual,
+            x11_context->visual_info->depth, InputOutput, x11_context->visual_info->visual,
             CWColormap | CWEventMask | CWOverrideRedirect | CWBorderPixel | CWBackPixmap, &window_attr);
         if(!self->window) {
             fprintf(stderr, "mgl error: XCreateWindow failed\n");