From b646bfc511cef8c55d2edb074a1a12adfbe70fd0 Mon Sep 17 00:00:00 2001
From: Peter Evans <pevans@activecampaign.com>
Date: Sat, 16 Dec 2017 22:45:39 -0600
Subject: [PATCH] First stab at adding graphics.

This involves using glfw. This first commit creates a window but doesn't
do anything with it; it also just hangs until you can escape out
somehow.
---
 CMakeLists.txt       |  3 +++
 include/log.h        |  1 +
 include/vm_screen.h  |  8 ++++++++
 src/main.c           | 20 ++++++++++++++++++++
 src/vm_screen.c      | 36 ++++++++++++++++++++++++++++++++++++
 tests/CMakeLists.txt |  3 +++
 6 files changed, 71 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 314e427..99cdbec 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -17,3 +17,6 @@ link_directories(/usr/local/lib)
 
 # our bullshit
 add_executable(erc ${sources} src/main.c)
+
+# Graphics
+target_link_libraries(erc glfw)
diff --git a/include/log.h b/include/log.h
index 6d1d22c..b305068 100644
--- a/include/log.h
+++ b/include/log.h
@@ -12,6 +12,7 @@ enum log_errcode {
     ERR_OOM,            // out of memory
     ERR_OOB,            // out of bounds
     ERR_BADFILE,
+    ERR_GFXINIT,        // couldn't initialize graphics
 };
 
 extern void log_write(int, const char *, ...);
diff --git a/include/vm_screen.h b/include/vm_screen.h
index c154484..a28fc49 100644
--- a/include/vm_screen.h
+++ b/include/vm_screen.h
@@ -1,6 +1,9 @@
 #ifndef _VM_SCREEN_H_
 #define _VM_SCREEN_H_
 
+#include <GLFW/glfw3.h>
+#include <stdbool.h>
+
 /*
  * If you just want to plot a single pixel, you can use this macro to
  * abstract away the need to indicate the x/y dimensions (as those must
@@ -10,6 +13,8 @@
     vm_screen_draw_rect(context, xpos, ypos, 1, 1)
 
 typedef struct {
+    GLFWwindow *window;
+
     /*
      * These form the components of an RGBA composite color. 
      */
@@ -19,6 +24,9 @@ typedef struct {
     int color_alpha;
 } vm_screen_context;
 
+extern int vm_screen_add_window(vm_screen_context *);
+extern int vm_screen_init();
+extern void vm_screen_finish();
 extern void vm_screen_draw_rect(vm_screen_context *, int, int, int, int);
 extern void vm_screen_free_context(vm_screen_context *);
 extern vm_screen_context *vm_screen_new_context();
diff --git a/src/main.c b/src/main.c
index eea527f..31d3e7b 100644
--- a/src/main.c
+++ b/src/main.c
@@ -14,6 +14,7 @@
 #include "apple2.h"
 #include "log.h"
 #include "option.h"
+#include "vm_screen.h"
 
 /*
  * This function will establish the base environment that we want to use
@@ -43,6 +44,8 @@ init(int argc, char **argv)
 
     // We're literally using stdout in this heavy phase of development.
     log_open(stdout);
+
+    vm_screen_init();
 }
 
 /*
@@ -61,6 +64,8 @@ finish()
     }
 
     log_close();
+
+    vm_screen_finish();
 }
 
 /*
@@ -71,6 +76,7 @@ int
 main(int argc, char **argv)
 {
     apple2 *mach;
+    vm_screen_context *context;
     int err;
 
     init(argc, argv);
@@ -88,6 +94,20 @@ main(int argc, char **argv)
         exit(1);
     }
 
+    context = vm_screen_new_context();
+    if (context == NULL) {
+        fprintf(stderr, "Screen context failed!\n");
+        exit(1);
+    }
+
+    if (!vm_screen_add_window(context)) {
+        fprintf(stderr, "Window creation failed!\n");
+        exit(1);
+    }
+
+    for (;;) {
+    }
+
     // ha ha ha ha #nervous #laughter
     printf("Hello, world\n");
 }
diff --git a/src/vm_screen.c b/src/vm_screen.c
index 65fe7dd..0895a69 100644
--- a/src/vm_screen.c
+++ b/src/vm_screen.c
@@ -11,6 +11,22 @@
 #include "log.h"
 #include "vm_screen.h"
 
+int
+vm_screen_init()
+{
+    if (!glfwInit()) {
+        return ERR_GFXINIT;
+    }
+
+    return OK;
+}
+
+void
+vm_screen_finish()
+{
+    glfwTerminate();
+}
+
 /*
  * Return a new screen context. We also set the color to black.
  */
@@ -29,6 +45,20 @@ vm_screen_new_context()
     return context;
 }
 
+int
+vm_screen_add_window(vm_screen_context *context)
+{
+    context->window = glfwCreateWindow(320, 240, "erc", NULL, NULL);
+    if (context->window == NULL) {
+        log_critical("Could not create a window");
+        return ERR_GFXINIT;
+    }
+
+    glfwMakeContextCurrent(context->window);
+
+    return OK;
+}
+
 /*
  * Free the contents of a screen context.
  */
@@ -38,6 +68,12 @@ vm_screen_free_context(vm_screen_context *context)
     free(context);
 }
 
+bool
+vm_screen_active(vm_screen_context *context)
+{
+    return !glfwWindowShouldClose(context->window);
+}
+
 /*
  * Set the color of a screen context to a given RGBA value.
  */
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 3db6788..0015186 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -23,3 +23,6 @@ add_executable(erc-test ${sources} ${test_sources})
 
 # Our unit-testing library
 target_link_libraries(erc-test criterion)
+
+# Graphics
+target_link_libraries(erc-test glfw)