[ui] Add the beginnings of an immediate mode UI

Based on the articles on Hidden Grove
(https://www.rfleury.com/archive?sort=new). So far, I can get a
non-functional button on the screen :)

include/QF/ui/imui.h

@@ -0,0 +1,89 @@
+/*
+	imui.h
+
+	Immediate mode user interface
+
+	Copyright (C) 2023 Bill Currie <bill@taniwha.org>
+
+	Author: Bill Currie <bill@taniwha.org>
+	Date: 2023/07/01
+
+	This program is free software; you can redistribute it and/or
+	modify it under the terms of the GNU General Public License
+	as published by the Free Software Foundation; either version 2
+	of the License, or (at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+	See the GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with this program; if not, write to:
+
+		Free Software Foundation, Inc.
+		59 Temple Place - Suite 330
+		Boston, MA  02111-1307, USA
+
+*/
+
+#ifndef __QF_ui_imui_h
+#define __QF_ui_imui_h
+
+typedef struct imui_ctx_s imui_ctx_t;
+struct canvas_system_s;
+
+typedef enum IMUI_SizeKind {
+	IMUI_SizeKind_Null,
+	IMUI_SizeKind_Pixels,
+	IMUI_SizeKind_TextContent,
+	IMUI_SizeKind_PercentOfParent,
+	IMUI_SizeKind_ChildrenSum,
+} IMUI_SizeKind;
+
+typedef enum IMUI_Axis {
+	IMUI_Axis_X,
+	IMUI_Axis_Y,
+	IMUI_Axis_count,
+} IMUI_Axis;
+
+typedef struct imui_size {
+	IMUI_SizeKind kind;
+	float       value;
+	float       strictness;
+} imui_size;
+
+typedef struct imui_layout_s {
+	imui_size semantic_size[IMUI_Axis_count];
+} imui_layout_t;
+
+imui_ctx_t *IMUI_NewContext (struct canvas_system_s canvas_sys,
+							 const char *font, float fontsize);
+void IMUI_DestroyContext (imui_ctx_t *ctx);
+
+void IMUI_SetVisible (imui_ctx_t *ctx, bool visible);
+void IMUI_SetSize (imui_ctx_t *ctx, int xlen, int ylen);
+void IMUI_Draw (imui_ctx_t *ctx);
+
+bool IMUI_Button (imui_ctx_t *ctx, const char *label);
+bool IMUI_Checkbox (imui_ctx_t *ctx, bool *flag, const char *label);
+void IMUI_Radio (imui_ctx_t *ctx, int *state, int value, const char *label);
+void IMUI_Slider (imui_ctx_t *ctx, float *value, float minval, float maxval,
+				  const char *label);
+
+// #define IMUI_context to an imui_ctx_t * variable
+
+#define UI_Button(label) \
+	IMUI_Button(IMUI_context, label)
+
+#define UI_Checkbox(flag, label) \
+	IMUI_Checkbox(IMUI_context, flag, label)
+
+#define UI_Radio(state, value, label) \
+	IMUI_Radio(IMUI_context, state, value, label)
+
+#define UI_Slider(value, minval, maxval, label) \
+	IMUI_Slider(IMUI_context, value, minval, maxval, label)
+
+#endif//__QF_ui_imui_h

libs/ui/Makemodule.am

@@ -22,6 +22,7 @@ libs_ui_libQFgui_la_DEPENDENCIES=	$(gui_deps) $(ui_deps)
 libs_ui_libQFgui_la_SOURCES= \
 	libs/ui/canvas.c \
 	libs/ui/font.c \
+	libs/ui/imui.c \
 	libs/ui/text.c
 
 libs_ui_libQFui_la_LDFLAGS=		$(lib_ldflags)

libs/ui/imui.c

@@ -0,0 +1,235 @@
+/*
+	imui.c
+
+	Immediate mode user inferface
+
+	Copyright (C) 2023 Bill Currie <bill@taniwha.org>
+
+	Author: Bill Currie <bill@taniwha.org>
+	Date: 2023/07/01
+
+	This program is free software; you can redistribute it and/or
+	modify it under the terms of the GNU General Public License
+	as published by the Free Software Foundation; either version 2
+	of the License, or (at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+	See the GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with this program; if not, write to:
+
+		Free Software Foundation, Inc.
+		59 Temple Place - Suite 330
+		Boston, MA  02111-1307, USA
+
+*/
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+#include <stdlib.h>
+#include <string.h>
+
+#include "QF/ecs.h"
+#include "QF/hash.h"
+#include "QF/progs.h"
+#include "QF/quakeio.h"
+
+#include "QF/ui/canvas.h"
+#include "QF/ui/font.h"
+#include "QF/ui/imui.h"
+#include "QF/ui/text.h"
+
+typedef struct imui_state_s {
+	struct imui_state_s *next;
+	struct imui_state_s **prev;
+	char       *label;
+	uint32_t    label_len;
+	int         key_offset;
+	uint32_t    entity;
+	bool        pressed;
+} imui_state_t;
+
+struct imui_ctx_s {
+	canvas_system_t csys;
+	uint32_t    canvas;
+	ecs_system_t vsys;
+	text_system_t tsys;
+	view_t      root_view;
+	hashctx_t  *hashctx;
+	hashtab_t  *tab;
+	PR_RESMAP (imui_state_t) state_map;
+	imui_state_t *states;
+	font_t     *font;
+};
+
+static imui_state_t *
+imui_state_new (imui_ctx_t *ctx)
+{
+	imui_state_t *state = PR_RESNEW (ctx->state_map);
+	*state = (imui_state_t) {
+		.next = ctx->states,
+		.prev = &ctx->states,
+		.entity = nullent,
+	};
+	if (ctx->states) {
+		ctx->states->prev = &state->next;
+	}
+	ctx->states = state;
+	return state;
+}
+/*
+static void
+imui_state_free (imui_ctx_t *ctx, imui_state_t *state)
+{
+	if (state->next) {
+		state->next->prev = state->prev;
+	}
+	*state->prev = state->next;
+	PR_RESFREE (ctx->state_map, state);
+}
+*/
+static imui_state_t *
+imui_get_state (imui_ctx_t *ctx, const char *label)
+{
+	int         key_offset = 0;
+	uint32_t    label_len = ~0u;
+	const char *key = strstr (label, "##");
+	if (key) {
+		// key is '###': hash only past this
+		if (key[2] == '#') {
+			key_offset = (key += 3) - label;
+		}
+		label_len = key - label;
+	} else {
+		key = label;
+	}
+	imui_state_t *state = Hash_Find (ctx->tab, key);
+	if (state) {
+		return state;
+	}
+	state = imui_state_new (ctx);
+	state->label = strdup (label);
+	state->label_len = label_len == ~0u ? strlen (label) : label_len;
+	state->key_offset = key_offset;
+	Hash_Add (ctx->tab, state);
+	return state;
+}
+
+static const char *
+imui_state_getkey (const void *obj, void *data)
+{
+	auto state = (const imui_state_t *) obj;
+	return state->label + state->key_offset;
+}
+
+imui_ctx_t *
+IMUI_NewContext (canvas_system_t canvas_sys, const char *font, float fontsize)
+{
+	imui_ctx_t *ctx = malloc (sizeof (imui_ctx_t));
+	uint32_t canvas;
+	*ctx = (imui_ctx_t) {
+		.csys = canvas_sys,
+		.canvas = canvas = Canvas_New (canvas_sys),
+		.vsys = { canvas_sys.reg, canvas_sys.view_base },
+		.tsys = { canvas_sys.reg, canvas_sys.view_base, canvas_sys.text_base },
+		.root_view = Canvas_GetRootView (canvas_sys, canvas),
+		.tab = Hash_NewTable (511, imui_state_getkey, 0, ctx, &ctx->hashctx),
+	};
+
+	auto fpath = Font_SystemFont (font);
+	if (fpath) {
+		QFile *file = Qopen (fpath, "rb");
+		if (file) {
+			ctx->font = Font_Load (file, fontsize);
+			//Qclose (file); FIXME closed by QFS_LoadFile
+		}
+		free (fpath);
+	}
+	return ctx;
+}
+
+void
+IMUI_DestroyContext (imui_ctx_t *ctx)
+{
+	for (auto s = ctx->states; s; s = s->next) {
+		free (s->label);
+	}
+	PR_RESDELMAP (ctx->state_map);
+
+	if (ctx->font) {
+		Font_Free (ctx->font);
+	}
+
+	Hash_DelTable (ctx->tab);
+	Hash_DelContext (ctx->hashctx);
+	free (ctx);
+}
+
+void
+IMUI_SetVisible (imui_ctx_t *ctx, bool visible)
+{
+	*Canvas_Visible (ctx->csys, ctx->canvas) = visible;
+}
+
+void
+IMUI_SetSize (imui_ctx_t *ctx, int xlen, int ylen)
+{
+	View_SetLen (ctx->root_view, xlen, ylen);
+	View_UpdateHierarchy (ctx->root_view);
+}
+
+void
+IMUI_Draw (imui_ctx_t *ctx)
+{
+	View_UpdateHierarchy (ctx->root_view);
+}
+
+bool
+IMUI_Button (imui_ctx_t *ctx, const char *label)
+{
+	auto state = imui_get_state (ctx, label);
+	if (state->entity == nullent) {
+		auto view = View_New (ctx->vsys, ctx->root_view);
+		state->entity = view.id;
+
+		*(byte*) Ent_AddComponent (view.id, ctx->csys.base + canvas_fill,
+								   ctx->csys.reg) = 0;
+
+		View_SetVisible (view, 1);
+		View_SetGravity (view, grav_northwest);
+		View_SetResize (view, 0, 0);
+
+		auto text = Text_StringView (ctx->tsys, view, ctx->font,
+									 state->label, state->label_len, 0, 0);
+		View_SetVisible (text, 1);
+		Ent_SetComponent (text.id, ctx->csys.base + canvas_glyphs, ctx->csys.reg,
+						  Ent_GetComponent (text.id, ctx->csys.text_base + text_passage_glyphs, ctx->csys.reg));
+		auto len = View_GetLen (text);
+		View_SetLen (view, len.x, len.y);
+	}
+	return state->pressed;
+}
+
+bool
+IMUI_Checkbox (imui_ctx_t *ctx, bool *flag, const char *label)
+{
+	auto state = imui_get_state (ctx, label);
+	if (state->entity == nullent) {
+	}
+	return *flag;
+}
+
+void
+IMUI_Radio (imui_ctx_t *ctx, int *state, int value, const char *label)
+{
+}
+
+void
+IMUI_Slider (imui_ctx_t *ctx, float *value, float minval, float maxval,
+			 const char *label)
+{
+}