examples: Add multiple viewports example program

Add a new multiple viewports example program which shows how to attach
2 viewports to the CogShell. Each viewport iterates over a couple
of views.

examples/meson.build

@@ -6,3 +6,10 @@ executable('viewport',
     dependencies: cogcore_dep,
     install: false,
 )
+
+executable('viewports',
+    'viewports.c',
+    c_args: examples_c_args,
+    dependencies: cogcore_dep,
+    install: false,
+)

examples/viewports.c

@@ -0,0 +1,85 @@
+/*
+ * viewports.c
+ * Copyright (C) 2023 Igalia S.L.
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include "../core/cog.h"
+
+typedef struct {
+    CogViewport *views;
+    gsize        current_index;
+} TimeoutData;
+
+static gboolean
+on_timeout_tick(TimeoutData *data)
+{
+    if (++data->current_index >= cog_viewport_get_n_views(data->views))
+        data->current_index = 0;
+
+    CogView *view = cog_viewport_get_nth_view(data->views, data->current_index);
+    g_message("Set visible view %zu <%p>", data->current_index, view);
+    cog_viewport_set_visible_view(data->views, view);
+
+    return G_SOURCE_CONTINUE;
+}
+
+int
+main(int argc, char *argv[])
+{
+    if (argc < 2) {
+        g_printerr("Usage: %s <URL> [URL...]\n", argv[0]);
+        return EXIT_FAILURE;
+    }
+
+    g_set_prgname("view-stacks");
+
+    g_autoptr(CogShell) shell = cog_shell_new(NULL, FALSE);
+    g_autoptr(GError)   error = NULL;
+
+    g_autoptr(CogPlatform) platform = cog_platform_get();
+    if (!cog_platform_setup(platform, shell, NULL, &error))
+        g_error("Cannot configure platform: %s", error->message);
+
+    g_autoptr(GMainLoop) loop = g_main_loop_new(NULL, FALSE);
+
+    CogViewport *viewport0 = cog_viewport_new();
+    cog_shell_add_viewport(shell, viewport0);
+
+    for (int i = 1; i < argc; i++) {
+        g_autoptr(CogView) view = cog_view_new(NULL);
+        cog_platform_init_web_view(platform, WEBKIT_WEB_VIEW(view));
+        cog_viewport_add(viewport0, view);
+        webkit_web_view_load_uri(WEBKIT_WEB_VIEW(view), argv[i]);
+        g_message("Viewport #0. Created view %p, URI %s", view, argv[i]);
+    }
+
+    TimeoutData data0 = {
+        .views = viewport0,
+        .current_index = SIZE_MAX,
+    };
+    g_timeout_add_seconds(5, (GSourceFunc) on_timeout_tick, &data0);
+    on_timeout_tick(&data0);
+
+    CogViewport *viewport1 = cog_viewport_new();
+    cog_shell_add_viewport(shell, viewport1);
+
+    for (int i = 1; i < argc; i++) {
+        g_autoptr(CogView) view = cog_view_new(NULL);
+        cog_platform_init_web_view(platform, WEBKIT_WEB_VIEW(view));
+        cog_viewport_add(viewport1, view);
+        webkit_web_view_load_uri(WEBKIT_WEB_VIEW(view), argv[i]);
+        g_message("Viewport #1. Created view %p, URI %s", view, argv[i]);
+    }
+
+    TimeoutData data1 = {
+        .views = viewport1,
+        .current_index = SIZE_MAX,
+    };
+    g_timeout_add_seconds(7, (GSourceFunc) on_timeout_tick, &data1);
+    on_timeout_tick(&data1);
+
+    g_main_loop_run(loop);
+    return EXIT_SUCCESS;
+}