[gnome-devel-docs] tutorials C: Scale sample/page/image

[Tiffany Antopolski <antopolski src gnome org>]

commit 3d433ec784f3aaf1379e54ef08aea5c178658a73
Author: Monica Kochofar <monicakochofar gmail com>
Date:   Thu Jul 5 20:33:12 2012 -0400

    tutorials C: Scale sample/page/image

 platform-demos/C/media/scale2.png |  Bin 0 -> 7897 bytes
 platform-demos/C/samples/scale.c  |  156 +++++++++++++++++++++++++++++++++++++
 platform-demos/C/scale.c.page     |   39 +++++++++
 3 files changed, 195 insertions(+), 0 deletions(-)
---
diff --git a/platform-demos/C/media/scale2.png b/platform-demos/C/media/scale2.png
new file mode 100644
index 0000000..9aefcce
Binary files /dev/null and b/platform-demos/C/media/scale2.png differ
diff --git a/platform-demos/C/samples/scale.c b/platform-demos/C/samples/scale.c
new file mode 100644
index 0000000..c384c01
--- /dev/null
+++ b/platform-demos/C/samples/scale.c
@@ -0,0 +1,156 @@
+#include <gtk/gtk.h>
+
+
+
+/* This is the callback function. 
+ * It is a handler function which reacts to the signal. 
+ * In this case, it will notify the user the value of their scale as a label.
+ */
+static void
+hscale_moved (GtkRange *range,
+              gpointer  user_data)
+{
+   GtkWidget *label = user_data;
+
+   /* Get the value of the range, and convert it into a string which will be
+    * used as a new label for the horizontal scale.
+    * %.0f - stands for a double that will have 0 decimal places.
+    */
+   gdouble pos = gtk_range_get_value (range);
+   /* Note: Using g_strdup_printf returns a string that must be freed. 
+    * (In which is done below)
+    */
+   gchar *str = g_strdup_printf ("Horizontal scale is %.0f", pos);
+   gtk_label_set_text (GTK_LABEL (label), str);
+
+   g_free(str);
+}
+
+
+
+/* This is the second callback function. It is a handler function which 
+ * reacts to the signal. It does the same thing as the function above, except with
+ * the vertical scale.
+ */
+vscale_moved (GtkRange *range,
+              gpointer  user_data)
+{
+   GtkWidget *label = user_data;
+   
+   gdouble pos = gtk_range_get_value (range);
+   /* %.1f - stands for a double that will have 1 decimal place */
+   gchar *str = g_strdup_printf ("Vertical scale is %.1f", pos);
+   gtk_label_set_text (GTK_LABEL (label), str);
+
+   
+   g_free (str);
+}
+
+
+
+static void
+activate (GtkApplication *app,
+          gpointer        user_data)
+{
+  /* Declare variables */
+  GtkWidget *window;
+  GtkWidget *h_scale;
+  GtkWidget *v_scale;
+  GtkWidget *hlabel;
+  GtkWidget *vlabel;
+  GtkWidget *grid;
+
+  /* The Adjustment object represents a value 
+   * which has an associated lower and upper bound.
+   */
+  GtkAdjustment *hadjustment;
+  GtkAdjustment *vadjustment;
+
+  /* Create a window with a title and a default size */
+  window = gtk_application_window_new (app);
+  gtk_window_set_title (GTK_WINDOW (window), "Scale Example");
+  gtk_window_set_default_size (GTK_WINDOW (window), 400, 300);
+  gtk_container_set_border_width (GTK_CONTAINER (window), 5);
+
+  /* Two labels to be shown in the window */
+  hlabel = gtk_label_new ("Move the scale handle...");
+  vlabel = gtk_label_new ("Move the scale handle...");
+
+   
+  /* gtk_adjustment_new takes six parameters, three of which 
+   * may be difficult to understand:
+   * step increment- move the handle with the arrow keys on your keyboard to see.
+   * page increment - move the handle by clicking away from it 
+   * on the scale to see.
+   * page size - not used here.
+   */
+  hadjustment = gtk_adjustment_new (0, 0, 100, 5, 10, 0);
+  vadjustment = gtk_adjustment_new (50, 0, 100, 5, 10, 0); 
+
+  /* Create the Horizontal scale, making sure the 
+   * digits used have no decimals.
+   */
+  h_scale = gtk_scale_new (GTK_ORIENTATION_HORIZONTAL, hadjustment);
+  gtk_scale_set_digits (GTK_SCALE (h_scale), 0); 
+
+  /* Allow it to expand horizontally (if there's space), and 
+   * set the vertical alignment
+   */
+  gtk_widget_set_hexpand (h_scale, TRUE);
+  gtk_widget_set_valign (h_scale, GTK_ALIGN_START);
+  
+  /* Connecting the "value-changed" signal for the horizontal scale 
+   * to the appropriate callback function. 
+   * take note that GtkRange is part of GtkScale's Object Hierarchy.
+   */
+  g_signal_connect (h_scale, 
+                    "value-changed", 
+                    G_CALLBACK (hscale_moved), 
+                    hlabel);
+
+
+
+  /* Create the Vertical scale. This time, we will see what happens 
+   * when the digits arent initially set.
+   */
+  v_scale = gtk_scale_new (GTK_ORIENTATION_VERTICAL, vadjustment);
+  gtk_widget_set_vexpand (v_scale, TRUE);
+
+  /* Connecting the "value-changed" signal for the vertical scale to 
+   * the appropriate callback function.
+   */
+  g_signal_connect (v_scale, 
+                    "value-changed", 
+                    G_CALLBACK (vscale_moved), 
+                    vlabel);
+
+  /* Create a grid and arrange everything accordingly */
+  grid = gtk_grid_new ();
+  gtk_grid_set_column_spacing (GTK_GRID (grid), 10);
+  gtk_grid_set_column_homogeneous (GTK_GRID (grid), TRUE);
+  gtk_grid_attach (GTK_GRID (grid), h_scale, 0, 0, 1, 1);
+  gtk_grid_attach (GTK_GRID (grid), v_scale, 1, 0, 1, 1);
+  gtk_grid_attach (GTK_GRID (grid), hlabel, 0, 1, 1, 1);
+  gtk_grid_attach (GTK_GRID (grid), vlabel, 1, 1, 1, 1);
+  
+
+  gtk_container_add (GTK_CONTAINER (window), grid);
+
+  gtk_widget_show_all (window);
+}
+
+
+
+int
+main (int argc, char **argv)
+{
+  GtkApplication *app;
+  int status;
+
+  app = gtk_application_new ("org.gtk.example", G_APPLICATION_FLAGS_NONE);
+  g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
+  status = g_application_run (G_APPLICATION (app), argc, argv);
+  g_object_unref (app);
+
+  return status;
+}
diff --git a/platform-demos/C/scale.c.page b/platform-demos/C/scale.c.page
new file mode 100644
index 0000000..d25c7c8
--- /dev/null
+++ b/platform-demos/C/scale.c.page
@@ -0,0 +1,39 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<page xmlns="http://projectmallard.org/1.0/";
+      xmlns:xi="http://www.w3.org/2001/XInclude";
+      type="guide" style="task"
+      id="scale.c">
+  <info>
+    <link type="guide" xref="beginner.c#entry"/>
+    <link type="seealso" xref="grid.c"/>
+    <link type="seealso" xref="label.c"/>
+    <revision version="0.2" date="2012-07-04" status="draft"/>
+
+    <credit type="author copyright">
+      <name>Monica Kochofar</name>
+      <email>monicakochofar gmail com</email>
+      <years>2012</years>
+    </credit>
+
+    <desc>A slider widget for selecting a value from a range</desc>
+  </info>
+
+  <title>Scale</title>
+
+  <media type="image" mime="image/png" src="media/scale2.png"/>
+  <p>Slide the scales!</p>
+
+      <code mime="text/x-csrc" style="numbered">
+<xi:include href="samples/scale.c" parse="text"><xi:fallback/></xi:include></code>
+<p>
+  In this sample we used the following:
+</p>
+<list>
+  <item><p><link href="http://developer.gnome.org/gtk3/3.4/GtkApplication.html";>GtkApplication</link></p></item>
+  <item><p><link href="http://developer.gnome.org/gtk3/3.4/GtkWindow.html";>GtkWindow</link></p></item>
+  <item><p><link href="http://developer.gnome.org/gtk3/stable/GtkScale.html";>GtkScale</link></p></item>
+  <item><p><link href="http://developer.gnome.org/gtk3/stable/GtkRange.html";>GtkRange</link></p></item>
+  <item><p><link href="http://developer.gnome.org/gtk3/stable/GtkAdjustment.html";>GtkAdjustment</link></p></item>
+  <item><p><link href="http://developer.gnome.org/glib/stable/glib-String-Utility-Functions.html#g-strdup-printf";>String Utility Functions</link></p></item>
+</list>
+</page>