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 +1,14 @@
+/*
+ * 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, int x, int y);
+
+#endif /* _APPS_ANIMATION_H_ */

apps/image.c

@@ -0,0 +1,122 @@
+/*
+ * 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)
+#define D(x) twin_double_to_fixed(x)
+#define ASSET_PATH "assets/"
+#define APP_WIDTH 400
+#define APP_HEIGHT 400
+typedef struct {
+    twin_widget_t widget;
+    twin_pixmap_t **pixes;
+    int image_idx;
+} apps_image_t;
+
+static const char *tvg_files[] = {
+    /* https://dev.w3.org/SVG/tools/svgweb/samples/svg-files/ */
+    ASSET_PATH "tiger.tvg",
+    /* https://tinyvg.tech/img/chart.svg */
+    ASSET_PATH "chart.tvg",
+    /* https://freesvg.org/betrayed */
+    ASSET_PATH "comic.tvg",
+    /* https://github.com/PapirusDevelopmentTeam/papirus-icon-theme */
+    ASSET_PATH "folder.tvg",
+    /* https://materialdesignicons.com/ */
+    ASSET_PATH "shield.tvg",
+    /* https://tinyvg.tech/img/flowchart.png */
+    ASSET_PATH "flowchart.tvg",
+};
+
+static void _apps_image_paint(apps_image_t *img)
+{
+    twin_operand_t srcop = {
+        .source_kind = TWIN_PIXMAP,
+        .u.pixmap = img->pixes[img->image_idx],
+    };
+
+    twin_composite(_apps_image_pixmap(img), 0, 0, &srcop, 0, 0, NULL, 0, 0,
+                   TWIN_SOURCE, APP_WIDTH, APP_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_button_signal(maybe_unused twin_button_t *button,
+                                      twin_button_signal_t signal,
+                                      void *closure)
+{
+    if (signal != TwinButtonSignalDown)
+        return;
+
+    apps_image_t *img = closure;
+    const int n = sizeof(tvg_files) / sizeof(tvg_files[0]);
+    img->image_idx = img->image_idx == n - 1 ? 0 : img->image_idx + 1;
+    if (!img->pixes[img->image_idx]) {
+        twin_pixmap_t *pix = twin_tvg_to_pixmap_scale(
+            tvg_files[img->image_idx], TWIN_ARGB32, APP_WIDTH, APP_HEIGHT);
+        if (!pix)
+            return;
+        img->pixes[img->image_idx] = pix;
+    }
+    _twin_widget_queue_paint(&img->widget);
+}
+
+static void _apps_image_init(apps_image_t *img,
+                             twin_box_t *parent,
+                             twin_dispatch_proc_t dispatch)
+{
+    static twin_widget_layout_t preferred = {0, 0, 1, 1};
+    preferred.height = parent->widget.window->screen->height * 3.0 / 4.0;
+    _twin_widget_init(&img->widget, parent, 0, preferred, dispatch);
+    img->image_idx = 0;
+    img->pixes = calloc(sizeof(tvg_files), sizeof(twin_pixmap_t *));
+    img->pixes[0] = twin_tvg_to_pixmap_scale(tvg_files[0], TWIN_ARGB32,
+                                             APP_WIDTH, APP_HEIGHT);
+    twin_button_t *button =
+        twin_button_create(parent, "Next Image", 0xFF482722, D(10),
+                           TwinStyleBold | TwinStyleOblique);
+    twin_widget_set(&button->label.widget, 0xFFFEE4CE);
+    button->signal = _apps_image_button_signal;
+    button->closure = img;
+    button->label.widget.shape = TwinShapeRectangle;
+}
+
+static apps_image_t *apps_image_create(twin_box_t *parent)
+{
+    apps_image_t *img = malloc(sizeof(apps_image_t));
+
+    _apps_image_init(img, parent, _apps_image_dispatch);
+    return img;
+}
+
+void apps_image_start(twin_screen_t *screen, const char *name, int x, int y)
+{
+    twin_toplevel_t *toplevel =
+        twin_toplevel_create(screen, TWIN_ARGB32, TwinWindowApplication, x, y,
+                             APP_WIDTH, APP_HEIGHT, name);
+    apps_image_t *img = apps_image_create(&toplevel->box);
+    (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", 20, 20);
+#endif
 
     twin_dispatch(tx);
 

configs/Kconfig

@@ -71,6 +71,10 @@ config LOADER_GIF
     bool "Enable GIF loader"
     default y
 
+config LOADER_TinyVG
+    bool "Enable TinyVG 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

include/twin.h

@@ -1186,6 +1186,15 @@ twin_work_t *twin_set_work(twin_work_proc_t work_proc,
 
 void twin_clear_work(twin_work_t *work);
 
+/*
+ * image-tvg.c
+ */
+
+twin_pixmap_t *twin_tvg_to_pixmap_scale(const char *filepath,
+                                        twin_format_t fmt,
+                                        twin_coord_t w,
+                                        twin_coord_t h);
+
 /*
  * backend
  */