Support TinyVG format decoding and rendering

Implemented support for decoding TinyVG format by parsing commands
step-by-step. Each decoded command is executed using twin's path
functions to render graphics. This enhances twin's capability to handle
compact vector graphics .

Ref:
https://tinyvg.tech/download/specification.pdf

Close #71

Makefile

@@ -86,6 +86,10 @@ ifeq ($(CONFIG_LOADER_GIF), y)
 libtwin.a_files-y += src/image-gif.c
 endif
 
+ifeq ($(CONFIG_LOADER_TVG), y)
+libtwin.a_files-y += src/image-tvg.c
+endif
+
 # Applications
 
 libapps.a_files-y := apps/dummy.c
@@ -96,6 +100,7 @@ libapps.a_files-$(CONFIG_DEMO_CALCULATOR) += apps/calc.c
 libapps.a_files-$(CONFIG_DEMO_LINE) += apps/line.c
 libapps.a_files-$(CONFIG_DEMO_SPLINE) += apps/spline.c
 libapps.a_files-$(CONFIG_DEMO_ANIMATION) += apps/animation.c
+libapps.a_files-$(CONFIG_DEMO_IMAGE) += apps/image.c
 
 libapps.a_includes-y := include
 

apps/apps_image.h

@@ -0,0 +1,18 @@
+/*
+ * Twin - A Tiny Window System
+ * Copyright (c) 2024 National Cheng Kung University
+ * All rights reserved.
+ */
+
+#ifndef _APPS_IMAGE_H_
+#define _APPS_IMAGE_H_
+
+#include <twin.h>
+
+void apps_image_start(twin_screen_t *screen,
+                      const char *name,
+                      const char *path,
+                      int x,
+                      int y);
+
+#endif /* _APPS_ANIMATION_H_ */

apps/image.c

@@ -0,0 +1,80 @@
+/*
+ * Twin - A Tiny Window System
+ * Copyright (c) 2024 National Cheng Kung University
+ * All rights reserved.
+ */
+
+#include <stdlib.h>
+
+#include "twin_private.h"
+
+#include "apps_image.h"
+
+#define _apps_image_pixmap(image) ((image)->widget.window->pixmap)
+
+typedef struct {
+    twin_widget_t widget;
+    twin_pixmap_t *pix;
+    twin_timeout_t *timeout;
+} apps_image_t;
+
+static void _apps_image_paint(apps_image_t *img)
+{
+    twin_operand_t srcop = {
+        .source_kind = TWIN_PIXMAP,
+        .u.pixmap = img->pix,
+    };
+    twin_composite(_apps_image_pixmap(img), 0, 0, &srcop, 0, 0, NULL, 0, 0,
+                   TWIN_SOURCE, img->pix->width, img->pix->height);
+}
+
+static twin_dispatch_result_t _apps_image_dispatch(twin_widget_t *widget,
+                                                   twin_event_t *event)
+{
+    apps_image_t *img = (apps_image_t *) widget;
+    if (_twin_widget_dispatch(widget, event) == TwinDispatchDone)
+        return TwinDispatchDone;
+    switch (event->kind) {
+    case TwinEventPaint:
+        _apps_image_paint(img);
+        break;
+    default:
+        break;
+    }
+    return TwinDispatchContinue;
+}
+
+static void _apps_image_init(apps_image_t *anim,
+                             twin_box_t *parent,
+                             twin_dispatch_proc_t dispatch)
+{
+    static const twin_widget_layout_t preferred = {0, 0, 1, 1};
+    _twin_widget_init(&anim->widget, parent, 0, preferred, dispatch);
+
+    anim->timeout = NULL;
+}
+
+static apps_image_t *apps_image_create(twin_box_t *parent, twin_pixmap_t *pix)
+{
+    apps_image_t *img = malloc(sizeof(apps_image_t));
+    img->pix = pix;
+    _apps_image_init(img, parent, _apps_image_dispatch);
+    return img;
+}
+
+void apps_image_start(twin_screen_t *screen,
+                      const char *name,
+                      const char *path,
+                      int x,
+                      int y)
+{
+    twin_pixmap_t *pix = twin_pixmap_from_file(path, TWIN_ARGB32);
+    if (!pix)
+        return;
+    twin_toplevel_t *toplevel =
+        twin_toplevel_create(screen, TWIN_ARGB32, TwinWindowApplication, x, y,
+                             pix->width, pix->height, name);
+    apps_image_t *img = apps_image_create(&toplevel->box, pix);
+    (void) img;
+    twin_toplevel_show(toplevel);
+}

apps/main.c

@@ -17,6 +17,7 @@
 #include "apps_calc.h"
 #include "apps_clock.h"
 #include "apps_hello.h"
+#include "apps_image.h"
 #include "apps_line.h"
 #include "apps_multi.h"
 #include "apps_spline.h"
@@ -127,6 +128,9 @@ int main(void)
     apps_animation_start(tx->screen, "Viewer", ASSET_PATH "nyancat.gif", 20,
                          20);
 #endif
+#if defined(CONFIG_DEMO_IMAGE)
+    apps_image_start(tx->screen, "Viewer", ASSET_PATH "chart.tvg", 20, 20);
+#endif
 
     twin_dispatch(tx);
 

configs/Kconfig

@@ -71,6 +71,10 @@ config LOADER_GIF
     bool "Enable GIF loader"
     default y
 
+config LOADER_TVG
+    bool "Enable TVG loader"
+    default y
+
 endmenu
 
 menu "Demo Applications"
@@ -113,4 +117,9 @@ config DEMO_ANIMATION
     bool "Build animation demo"
     default y
     depends on DEMO_APPLICATIONS 
+
+config DEMO_IMAGE
+    bool "Build image demo"
+    default y
+    depends on DEMO_APPLICATIONS 
 endmenu